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Last Updated :2024/11/16

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Master

Affiliation (Master)

  • Faculty of Fisheries Sciences　Marine Life Science　Aquaculture Biology

Affiliation (Master)

  • Faculty of Fisheries Sciences　Marine Life Science　Aquaculture Biology

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Profile and Settings

Degree

  • Doctor of Fisheries Sciences, Hokkaido University（Hokkaido University）

Profile and Settings

  • Name (Japanese)

    Takagi

  • Name (Kana)

    Yasuaki

  • Name

    200901028361363949

Achievement

Research Interests

  • wound healing   cosmetics   chondroitin sulfate   collagen peptide   collagenous scaffold   ECM   collagen   魚類生理学   Fish Physiology   

Research Areas

  • Life sciences / Marine/Aquatic life sciences / collagen peptide hydrolysate chondroitin sulfate
  • Life sciences / Aquaculture / sturgeon aquaculture caviar regional activation industry-academia-government collaboration
  • Life sciences / Cell biology / extracellular matrix regulation of cellular activity
  • Nanotechnology/Materials / Organic functional materials / Collagen cell scaffold tissue engineering regenerative medicine

Research Experience

  • 2002 - 2005 北海道大学教授（大学院水産科学研究科） 教授
  • 2002 - 2005 Professor,Professor, Hokkaido University, Graduate School of Fisheries Sciences

Education

  •        - 1990  Hokkaido University
  •        - 1990  Hokkaido University  Graduate School, Division of Fisheries

Committee Memberships

  • 2021/04 -2024/03   Japanese Society for Aquaculture Science (JSAS)   President

Awards

  • 1998 1998: Best Oral Presentation Award, 2nd International Symposium on Fish Otolith Research and Application

Published Papers

  • Qi Zhang, Shufang Hou, Yanmei Liu, Jia Du, Yongkang Jia, Qiushi Yang, Tingting Xu, Yasuaki Takagi, Dapeng Li, Xi Zhang
    Foods 13 (18) 2901 - 2901 2024/09/13 [Refereed][Not invited]
     
    The southern catfish (Silurus meridionalis) is an economically important carnivorous freshwater fish in China. In this study, we compared the properties of skin collagen from southern catfish fed with raw food (RF) and cooked food (CF). The skin collagen yield in the RF group (8.66 ± 0.11%) was significantly higher than that of the CF group (8.00 ± 0.27%). SDS-PAGE, circular dichroism spectroscopy, and FTIR analyses revealed that the collagen extracted from southern catfish skin in both groups was type I collagen, with a unique triple helix structure and high purity. The thermal denaturation temperature of collagen in the RF group (35.20 ± 0.11 °C) was significantly higher than that of the CF group (34.51 ± 0.25 °C). The DPPH free radical scavenging rates were 68.30 ± 2.41% in the RF collagen and 61.78 ± 3.91% in the CF collagen, which was higher than that found in most fish collagen. Both the RF and CF groups had high ability to form fibrils in vitro. Under the same conditions, the CF group exhibited faster fibril formation and a thicker fibril diameter (p < 0.05). In addition, the RF group exhibited significantly higher expression of col1a1 compared to the CF group. These results indicated that feeding southern catfish raw food contributed to collagen production, and the collagen from these fish may have potential in biomaterial applications.
  • Shuichiro Watanabe, Ken Matsuzaki, Utano Shimizu, Ichiro Higuchi, Takashi Todo, Yasuaki Takagi, Kazuhiro Ura
    Fisheries Science 90 (6) 907 - 924 0919-9268 2024/06/10 [Refereed][Not invited]
  • Md Rashidul Islam, Shunji Yunoki, Kazuhiro Ura, Yasuaki Takagi
    Sustainable Chemistry and Pharmacy 39 101612  2352-5541 2024/06 [Refereed][Not invited]
  • Linyan Shi, Kazuhiro Ura, Yasuaki Takagi
    Osteoarthritis and Cartilage Open 6 (2) 100450 - 100450 2665-9131 2024/06 [Refereed]
  • Yongkang Jia, Jia Du, Rujuan Xi, Qi Zhang, Li Li, Dapeng Li, Yasuaki Takagi, Xi Zhang
    Journal of Animal Science 102 0021-8812 2024/01/03 [Refereed][Not invited]
     
    Abstract Grass carp (Ctenopharyngodon idellus) is an economically important farmed fish. This experiment was conducted to study the effects of different culture salinities on the growth and muscle quality of grass carp. We found that salinity of 0 to 5 had no significant effect on the growth of grass carp, but it significantly decreased at salinities above 5. Compared to salinity 0, the protein content of serum was significantly higher at salinities of 3 and 5. However, all serum biochemical compound measured, except glucose and total protein, decreased significantly at salinity 9. Muscle textural properties of grass carp were significantly higher at salinities of 3 and 5 than at 0, 7, and 9. Salinities of 0 to 3 had no significant effect on muscle nutrition of grass carp, but this parameter tended to decrease at salinities above 7. Salinities of 3 and 5 significantly favored muscle growth and expression of collagen-related genes, whereas the opposite was true for salinities of 7 and 9. These results indicated that grass carp grew normally at salinities of 3 and 5, with some improvement in muscle quality, whereas salinities of 7 and 9 had a negative effect on growth and quality. Therefore, appropriate salinity levels can help to improve the muscle quality of grass carp without affecting their growth.
  • Dawei Meng, Yasuaki Takagi
    Sustainable Chemistry and Pharmacy 36 101299 - 101299 2352-5541 2023/12 [Refereed]
  • Naoya Terauchi, Dawei Meng, Wen Li, Haruto Inada, Kazuhiro Ura, Yasuaki Takagi
    Fisheries Science 89 (4) 527 - 535 0919-9268 2023/05/12 [Refereed]
  • Md Rashidul Islam, Wen Li, Yumi Ogata, Takeya Yoshioka, Kazuhiro Ura, Takagi Yasuaki
    Sustainable Chemistry and Pharmacy 31 100944 - 100944 2352-5541 2023/04 [Refereed][Not invited]
  • Boxue Yang, Wenzhao Li, Asuka Ishii, Ga-hyun Joe, Yutaka Shimizu, Yasuaki Takagi, Hiroki Saeki
    Waste and Biomass Valorization 1877-2641 2023/03/24
  • Dawei Meng, Wen Li, Xiaoqian Leng, Yasuaki Takagi, Zhiyuan Dai, Hao Du, Qiwei Wei
    Process Biochemistry 124 180 - 188 1359-5113 2023/01 [Refereed][Not invited]
  • Dawei Meng, Xiaoqian Leng, Yan Zhang, Jiang Luo, Hao Du, Yasuaki Takagi, Zhiyuan Dai, Qiwei Wei
    Carbohydrate Research 522 108685 - 108685 0008-6215 2022/12 [Refereed][Not invited]
  • Wen Li, Kazuhiro Ura, Yasuaki Takagi
    Current Research in Food Science 5 698 - 709 2665-9271 2022/04 [Refereed]
  • Tomoharu Yuhi, Osamu Nishimiya, Kaoru Ohno, Asami Takita, Takako Inoguchi, Kazuhiro Ura, Yasuaki Takagi
    Fisheries Science 88 (2) 259 - 273 0919-9268 2022/03 [Refereed][Not invited]
     
    Accumulation of yolk precursor protein in the oviparous egg is essential for embryo growth. Transferrin-like protein, also known as major yolk protein, is a major precursor protein in sea urchins and sea cucumbers. In sea urchins, a new yolk protein was recently detected in Strongylocentrotus intermedius and Mesocentrotus nudus eggs. This protein, tentatively named yolk-related protein (YRP), was thought to have important physiological functions for sea urchin gonadal growth and gametogenesis. To understand the relationship between YRP and vitellogenesis, we investigated the molecular structure of sea urchin YRP, quantified the transcript levels during oogenesis, and identified the presence of YRP in coelomic fluid. Using molecular cloning, we characterized one cDNA that encoded YRP (mn-yrp). Structural analysis revealed that mn-YRP is an apolipoprotein B (ApoB)-like protein that belongs to the large lipid transfer protein superfamily. Quantification of mn-yrp (mn-apob) transcripts showed that mn-apob is mainly expressed in the stomach during gonadal growth. Immunobiochemical methods using antiserum revealed that mn-ApoB was present in the coelomic fluid. These results indicate that ApoB has a role in the transport of nutrients, such as sugar, lipids, and carotenoids, from the digestive tract to eggs via coelomic fluid in sea urchin.
  • Preparation of collagen nanofibril-scaffold from the skin of catfish (Pangasianodon hypophthalmus) farmed in the Mekong Delta.
    Ho QP, Thi MTL, Huynh LH, Tran MP, Thi BTN, Takagi Y
    AACL Bioflux 124 180 - 188 2022 [Refereed][Not invited]
  • Wen Li, Naoya Terauchi, Dawei Meng, Nobuyuki Miyamoto, Naonobu Tsutsumi, Kazuhiro Ura, Yasuaki Takagi
    Sustainable Chemistry and Pharmacy 23 100499 - 100499 2352-5541 2021/10 [Refereed][Not invited]
  • Quoc Phong Ho, Takagi Yasuaki, Lien Huong Huynh, Thanh Tuyen Nguyen, Minh Phu Tran, Thi Minh Thuy Le, Luu Ngoc Hanh Cao
    Can Tho University Journal of Science 13 (Aquaculture) 64 - 72 2615-9422 2021/06/30 [Refereed][Not invited]
     
    This study was conducted to incorporate amine functional groups on the surface of hydroxyapatite to enhance its potential application in biomedical materials. Hydroxyapatite particles (HA) were synthesized from striped catfish (Pagasianodon hypophthalmus) bone and surface modified by grafting with (3-aminopropyl)triethoxysilane (APTES). Important factors affected grafting efficiency such as concentration of APTES, water content, reaction temperature and reaction time were studied. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were used to confirm the grafting reaction on HA surfaces. Grafting efficiency was evaluated based on intensity of characteristic absorption peaks of APTES. The experimental results showed that amine functional groups were successfully introduced on HA surface at optimal condition of 0.2 M APTES, 0.75 wt.% water content, at 60°C and 12-hour reaction time.
  • Thi Thanh Huong Do, Thi Kim Ha Nguyen, Tinh Em Nguyen, Minh Ky Tang, Takagi Yasuaki, Thanh Phuong Nguyen
    Can Tho University Journal of Science 13 (Aquaculture) 10 - 20 2615-9422 2021/06/30 [Refereed][Not invited]
     
    The effects of temperature on growth performance, survival rate, digestive enzymatic activities, and physiological responses of striped snakehead (Channa striata) at fry stage were evaluated. The study consisted of two trials including (1) determination of temperature threshold and (2) effects of different temperatures (24°C, 27°C (control), 30°C, 33°C and 36°C) on growth performance, survival rate, digestive enzyme activities and physiological parameters of striped snakehead fry stage for 90 days. The growth experiment was conducted in 500-L tank (250-L water) with triplicates. The stocking density was 300 individuals per tank. Striped snakehead at fry stage showed a high tolerance to temperature ranging from 10 to 40ºC. After 90 days, fish reared in 30°C performed the greatest weight and survival rate (13.1±3.12 g/fish and 15.5±4.63%, respectively). The number of red blood cells and hemoglobin concentrations increased with the increase in temperature. It was discovered that different temperatures (from 27 to 36°C) did not significantly influence the number of white blood cells, osmolality, and ion concentration of fish. Glucose and cortisol concentrations increased with temperature rises and peaked in fish reared at 36°C, while temperatures of 30oC and 33oC showed higher digestive enzyme activities. It proves that 30°C is the optimal level for striped snakehead fry rearing.
  • Hồ Quốc Phong, Ngọc Gia Ngân Võ, Huỳnh Liên Hương, Takagi Yasuaki, Lê Thị Minh Thủy, Nguyễn Việt Bách
    Can Tho University Journal of Science 57 (3) 1 - 9 1859-2333 2021/06/30 [Refereed][Not invited]
     
    Nghiên cứu được tiến hành nhằm gắn kết collagen trích ly từ da cá tra (Pangasiidae) lên bề mặt hydroxyapatite (HA) tổng hợp từ xương cá tra làm tăng khả năng ứng dụng trong lĩnh vực y sinh. Sau khi trích ly, collagen được gắn kết lên bề mặt HA thông qua cầu nối glutaraldehyde. Các hạt HA trước tiên gắn kết với 3 – amino propyl triethoxysilane (APTES) tạo nhóm chức amine trên bề mặt. Glutaraldehyde là cầu nối gắn kết HA và collagen thông qua phản ứng giữa nhóm chức amine và aldehyde. Các yếu tố ảnh đến sự gắn kết như nồng độ collagen, pH dung dịch phản ứng, thời gian và nhiệt độ của phản ứng được tiến hành khảo sát. Kết quả thí nghiệm cho thấy nồng độ collagen 1 mg/mL, dung dịch acetic acid hòa tan collagen có pH 3, thời gian phản ứng 3 giờ và nhiệt độ phản ứng 37C là điều kiện thích hợp để tiến hành gắn kết. Ngoài ra, kết quả chụp SEM cho thấy rằng các hạt HA được chế tạo có kích thước khoảng 1.000 nm và bị phủ một lớp collagen sau khi gắn kết.
  • Wen Li, Taishi Kobayashi, DaWei Meng, Nobuyuki Miyamoto, Naonobu Tsutsumi, Kazuhiro Ura, Yasuaki Takagi
    Food Bioscience 41 100991 - 100991 2212-4292 2021/06 [Refereed][Not invited]
  • Md. Rashidul Islam, Tomoharu Yuhi, Dawei Meng, Takeya Yoshioka, Yumi Ogata, Kazuhiro Ura, Yasuaki Takagi
    LWT-Food Science and Technology 142 110944 - 110944 0023-6438 2021/05 [Refereed][Not invited]
  • Xi Zhang, Huiyan Zhang, Shigeru Toriumi, Kazuhiro Ura, Yasuaki Takagi
    Aquaculture 529 735641 - 735641 0044-8486 2020/12 [Refereed][Not invited]
  • Md. Rashidul Islam, Tomoharu Yuhi, Kazuhiro Ura, Yasuaki Takagi
    Applied Sciences 10 (19) 6660 - 6660 2020/09/23 [Refereed][Not invited]
     
    To develop a new method for extracting gelatin from the sturgeon head, the conditions for pretreatment and extraction were optimized. Treatment at 65 °C (3–3.5 h) was enough to separate the head into mixed tissues (skin, scales, pectoral fins, muscle, bones, gills, and small cartilage pieces), skull cartilage, and liquid. From the intensities of α-, β- and γ-bands and yields, the optimized pretreatment conditions for type A and type B gelatin were 0.05 M HCl (1 h) and 0.1 M NaOH (1 h), respectively. The best extraction conditions were: (1) for type A gelatin: with distilled water (DW) (w/v 1:5) at 35 °C, pH 7 when stirring at 200 rpm for 3 h, and (2) for type B gelatin: with DW (w/v 1:5) at 50 °C, pH 8 when stirring at 200 rpm for 1 h. After the decalcification of extracted residues with 0.05 M HCl for 3 h, re-extraction of gelatin was possible. Under the best extraction conditions, yields of type A and B gelatins were 5.01 and 7.25% (dry gelatin weight/wet sample weight), respectively. Thus, it is possible to extract an industrial amount of gelatin from sturgeon heads, making them valuable by-products.
  • Dawei Meng, Wen Li, Kazuhiro Ura, Yasuaki Takagi
    International Journal of Biological Macromolecules 148 182 - 191 0141-8130 2020/04 [Refereed][Not invited]
  • Hồ Quốc Phong, Phan Đình Khôi, Huỳnh Liên Hương, Nguyễn Văn Nhã, Nguyễn Thị Bích Thuyền, Yasuaki Takagi, Lê Thị Minh Thủy, Trần Minh Phú
    Can Tho University Journal of Science 56 199 - 211 1859-2333 2020 [Refereed][Not invited]
  • Đỗ Thị Thanh Hương, Tăng Minh Kỳ, Nguyễn Thị Kim Hà, Nguyễn Tính Em, Takagi Yasuaki, Nguyễn Thanh Phương
    Can Tho University Journal of Science 56 11 - 19 1859-2333 2020 [Refereed][Not invited]
  • Major yolk protein binds folic acid in sea urchin
    Ura K, Goto T, Kitano Y, Nishimiya O, Takagi Y
    Aquaculture Science 68 309 - 316 2020 [Refereed][Not invited]
  • Quantitative changes of major yolk protein in the coelomic fluid and gonads of the sea urchin, Mesocentrotus nudus, during the reproductive cycle.
    Ura K, Suzuki N, Numata H, Tsue S, Satoh M, Takei N, Higuchi I, Yuhi T, Nishimiya O, Takagi Y
    Bull. Fish. Sci. Hokkaido Univ. 69 29 - 36 2019 [Refereed][Not invited]
  • Zhang X, Adachi S, Ura K, Takagi Y
    Int. J. Biol. Macromol. 137 809 - 820 2019 [Refereed][Not invited]
  • Moroi S, MiuraT, Tamura T, Zhang X, Ura K, Takagi Y
    Mater. Sci. Engineer. C 104 109925  2019 [Refereed][Not invited]
  • Meng D, Tanaka H, Kobayashi T, Hatayama H, Zhang X, Ura K, Yunoki S, Takagi Y
    Int. J. Biol. Macromol. 131 572 - 580 2019 [Refereed][Not invited]
     
    Non-mammalian collagens have attracted increasing attention for industrial and biomedical use. We have therefore evaluated extraction conditions and the biochemical properties of collagens from aquacultured sturgeon. Pepsin-soluble type I and type II collagen were respectively extracted from the skin and notochord of bester sturgeon by-products, with yields of 63.9 ± 0.19% and 35.5 ± 0.68%. Collagen extraction efficiency was improved by an alkaline pretreatment of the skin and notochord (fewer extraction cycles were required), but the final yields decreased to 56.2 ± 0.84% for type I and 31.8 ± 1.13% for type II. Alkaline pretreatment did not affect the thermal stability or triple-helical structure of both types of collagen. Types I and II collagen formed re-assembled fibril structures in vitro, under different conditions. Alkaline pretreatment slowed down the formation of type I collagen fibrils and specifically inhibited the formation of thick fibril-bundle structures. In contrast, alkaline pretreatment did not change type II collagen fibril formation. In conclusion, alkaline pretreatment of sturgeon skin and notochord is an effective method to accelerate collagen extraction process of types I and II collagen without changing their biochemical properties. However, it decreases the yield of both collagens and specifically changes the fibril-forming ability of type I collagen.
  • Zhang X, Wang J, Tang R, He X, Li L, Takagi Y, Li D
    Front. Physiol. 10 683  2019 [Refereed][Not invited]
  • Li W, Kobayashi T, Moroi S, Kotake H, Ikoma T, Saeki H, Ura K, Takagi Y
    Carbohydr. Polym. 214 303 - 310 2019 [Refereed][Not invited]
  • Nishimiya O, Teraoka Y, Gotoh T, Yuhi T, Higuchi I, Ura K, Takagi Y
    Fish. Sci. 85 (1) 127 - 135 0919-9268 2019 [Refereed][Not invited]
     
    The major yolk protein in sea urchins is a transferrin-like protein. In this report, a new component was detected in gonad extracts of Strongylocentrotus intermedius and Mesocentrotus nudus, which cross-reacts with antiserum against egg yolk proteins. We tentatively named them egg yolk-related proteins siYRP and mnYRP. The siYRP was purified from testis of S. intermedius by ammonium sulfate fractionation, anion exchange chromatography, affinity chromatography and gel filtration. Purified siYRP was >900kDa in size. The siYRP purified on SDS-PAGE under reducing conditions gave seven bands, corresponding to 93, 213 and >250kDa. Purified mnYRP displayed similar structural characteristics as siYRP. Purified siYRP and mnYRP were identified by tandem mass spectrometry and renamed as siVitellogenin (Vtg)-like and mnVtg-like proteins, respectively. Both Vtg-like proteins were confirmed to be lipoglycoproteins by staining with Sudan black and periodic acid-Schiff. A specific antiserum against the siVtg-like protein was raised in rabbit. Antiserum against the siVtg-like protein immunostained siVtg-like and mnVtg-like proteins. Immunochemical methods using the antiserum revealed that siVtg-like and mnVtg-like proteins were present in the ovary, testis and unfertilized eggs of both species. These results indicated that Vtg-like proteins have important physiological functions for gonadal growth and gametogenesis in sea urchins.
  • Yukiho Sasaoka, Hideki Kishimura, Shinji Adachi, Yasuaki Takagi
    Journal of Food Biochemistry 42 (2) e12478  1745-4514 2018/04/01 [Refereed][Not invited]
     
    We prepared collagen peptides (SCP) from sturgeon by-products: the skin, fin, and bone. The materials were pretreated and hydrolyzed by papain. Finally, we obtained 85.1 g of dried SCP powder from 864 g (wet weight) of the materials. In oral glucose tolerance test (OGTT) with ICR mice, blood glucose levels of SCP group were significantly lower than those of control group. Then, we fractionated SCP by Sephadex column chromatography and all fractions showed hypoglycemic effect. Further, we separated each peptide in the fractions by reversed-phase HPLC. Most of the peptides in these peaks consisted of Gly-X-Y (X and Y are optional amino acid residues) repetitive sequences which are common to the triple helical region of the collagen molecules. Moreover, many peptides contained Pro and Ala residues, which promises to serve as a DPP-IV inhibitor. Altogether, these results suggest the hypoglycemic effect of SCP may be caused by these structural properties. Practical applications: While sturgeon is famous and highly valuable for its salted egg “caviar” and meat, other parts such as skin, fin, and bone, that is, by-products are not fully utilized in seafood industry. In this study, we focused on whole utilization of a sturgeon and prepared collagen peptides (SCP) from sturgeon by-products. The yield of SCP was approximately 100 g SCP/kg wet by-products. In animal experiments, SCP showed hypoglycemic effect. Moreover, the effect is probably caused by Gly-X-Y repetitive sequences derived from the triple helical region of a collagen molecule. The mechanism might be related to DPP-IV inhibitory activity. SCP was white, odorless, and easily soluble in water and it could be advantages in using SCP as an ingredient for functional foods preventing Type 2 diabetes mellitus. The by-products of sturgeon will be a new fishery resource which could be used as a material for collagen peptides providing the hypoglycemic effect.
  • Puteri NE, Astawan M, Pulpi NS, Wresdiyati T, Takagi Y
    Food Sci. Tech. (Campinas) 31 (suppl 1) 147 - 153 2018 [Refereed][Not invited]
  • Morphology and anatomy of corallimorpharian Metarhodactis aff. boninensis from Thailand
    Dokkadew S, Kaewsuralikhit C, Takagi Y, Taparhudee W
    Journal of Fisheries and Environment 42 1 - 13 2018 [Refereed][Not invited]
  • Sato N, Furuta T, Takeda T, Miyabe Y, Ura K, Takagi Y, Yasui H, Kumagai Y, Kishimura H
    Journal of Food Biochemistry 43 (2) e12709 - e12709 0145-8884 2018 [Refereed][Not invited]
  • Yuki Okashita, Heng Wang, Shiori Tsue, Osamu Nishimiya, Kazuhiro Ura, Yasuaki Takagi
    FISHERIES SCIENCE 83 (5) 803 - 810 0919-9268 2017/09 [Refereed][Not invited]
     
    In the present study, we examined the localization of the major yolk protein (MYP) in the intestine of the sea urchin Strongylocentrotus intermedius. First, partial MYP complementary DNA was isolated from the sea urchin intestine. The expression level of MYP messenger RNA (mRNA) along the sea urchin digestive tract is highest in the intestine, so we performed in situ hybridization and immunohistochemical analysis using this tissue. No MYP mRNA was detected in the luminal epithelium, connective tissue, muscle tissue, or coelomic epithelium by in situ hybridization analysis. Positive immunohistochemical staining was observed in the luminal epithelium, inner epithelium and connective tissue, the signal being strongest in the latter. We conclude that MYP synthesized in the inner epithelial cells is moved to and stored in connective tissue and the luminal epithelium, before being secreted into the body cavity and the inner digestive cavity of the sea urchin.
  • Md. Tariful Islam Mredha, Nobuto Kitamura, Takayuki Nonoyama, Susumu Wada, Keiko Goto, Xi Zhang, Tasuku Nakajima, Takayuki Kurokawa, Yasuaki Takagi, Kazunori Yasuda, Jian Ping Gong
    BIOMATERIALS 132 85 - 95 0142-9612 2017/07 [Refereed][Not invited]
     
    Soft supporting tissues in the human body, such as cartilages and ligaments, are tough materials and firmly fixed to bones. These soft tissues, once injured, cannot regenerate spontaneously in vivo. Developing tough and biocompatible hydrogels as artificial soft supporting tissues would substantially improve outcomes after soft tissue injury. Collagen is the main rigid component in soft connective tissues which is organized in various hierarchical arrays. We have successfully developed a novel class of collagen fibril-based tough hydrogels based on the double network (DN) concept using swim bladder collagen (SBC) extracted from Bester sturgeon fish. The DN hydrogels, SBC/PDMAAm, are composed of physically/chemically crosslinked anisotropic SBC fibril as the first network and neutral, biocompatible poly(N,N'-dimethylacrylamide) (PDMAAm) as the second network. The anisotropic structure of SBC fibril network, which is well retained in the DN hydrogels, is formed by free injection method, taking advantage of the excellent fibrillogenesis capacity of SBC. The denaturation temperature of collagen is improved in the DN hydrogels. These DN gels possess anisotropic swelling behavior, exhibit excellent mechanical properties comparable to natural cartilage. The 4 weeks implantation of the gels in the osteochondral defect of rabbit knee also shows excellent biomechanical performance in vivo. Furthermore, the hydroxyapatite (HAp) coated DN gels, HAp/SBC/PDMAAm gels, strongly bond to bone after 4 weeks. This new class of collagen-based hybrid DN gels, as soft and elastic ceramics, having good biomechanical performance and strong bonding ability with bone would expand the choice for designing next generation orthopedic implants such as artificial cartilage, bone defect repair material in the load bearing region of the body. (C) 2017 Elsevier Ltd. All rights reserved.
  • Ura K, Wang H, Hori T, Aizawa S, Tsue S, Satoh M, Takei N, Hoshino K, Higuchi I, Sanuki S, Yuhi T, Nishimiya O, Takagi Y
    Aquaculture Science 日本水産増殖学会 65 (3) 231 - 237 0371-4217 2017 [Refereed][Not invited]
  • Noriko Azuma, Seishi Hagihara, Masaki Ichimura, Yasuaki Takagi, Kazuhiro Ura, Shinji Adachi
    ICHTHYOLOGICAL RESEARCH 64 (1) 139 - 144 1341-8998 2017/01 [Refereed][Not invited]
     
    Genetic characterization was performed in five individuals of wild Amur sturgeon Acipenser schrenckii, and/or its presumed hybrid caught around Hokkaido, using a mitochondrial DNA (mtDNA) marker and two markers of nuclear DNA (nDNA). Genetic analyses indicated that two of the five fish had the mtDNA haplotype of Kaluga, Huso dauricus, whereas the nDNA markers indicated signs for both A. schrenckii and H. dauricus genotypes, referring to a hybrid origin. The other three fish were plausibly pure A. schrenckii. The results indicated the importance of combined usage of mtDNA and nDNA markers for correct species identification in sturgeon.
  • Takayuki Nonoyama, Susumu Wada, Ryuji Kiyama, Nobuto Kitamura, Md. Tariful Islam Mredha, Xi Zhang, Takayuki Kurokawa, Tasuku Nakajima, Yasuaki Takagi, Kazunori Yasuda, Jian Ping Gong
    ADVANCED MATERIALS 28 (31) 6740 - + 0935-9648 2016/08 [Refereed][Not invited]
     
    On implanting hydroxyapatite-mineralized tough hydrogel into osteochondral defects of rabbits, osteogenesis spontaneously penetrates into the gel matrix owing to the semi-permeablility of the hydrogel. The gradient layer (around 40 mu m thick) contributes quite strong bonding of the gel to bone. This is the first success in realizing the robust osteointegration of tough hydrogels, and the method is simple and feasible for practical use.
  • Xi Zhang, Noriko Azuma, Seishi Hagihara, Shinji Adachi, Kazuhiro Ura, Yasuaki Takagi
    GENE 579 (1) 8 - 16 0378-1119 2016/03 [Refereed][Not invited]
     
    To characterize type I and II collagen in the Amur sturgeon at the molecular level, mRNAs encoding the pro alpha chain of both types of collagen were cloned and sequenced. Full sequences of both were obtained, and the molecular phylogeny based on the deduced amino acid sequence indicated that the correct sequences of the target genes were obtained. Analyses of primary structure of the pro alpha chains revealed that type I and II collagen share the basic structure of the prom chain of fibril collagen, but have different characteristics, especially in residues related to thermal stability. In the triple helical domain, Gly-Pro-Pro sequence stabilizing the tripeptide unit was more frequent in type II than in type I, and Gly-Gly, which likely decline in thermal stability, was more frequent in type I than in type II. These results suggested that the denaturation temperature of type II would be remarkably higher than type I. The spatial pattern of gene expression was analyzed by quantitative real-time PCR, which showed that relatively ubiquitous type I gene and strongly skewed distribution of type II gene, which highly expressed only in vertebra, snout cartilage, and notochord. This pattern was similar to the distribution pattern of each collagen protein detected by previous biochemical analyses using Amur and Bester sturgeons. The present study is the first report of the cloning of the full-length cDNAs for both of type I and type II collagen in the Amur sturgeon, and is the first comparative analysis of type I and II collagens in a sturgeon species at the molecular level. The results provide basic and general information on collagens in sturgeons. (C) 2015 Elsevier B.V. All rights reserved.
  • Frolan A. Aya, Vicar Stella N. Nillasca, Luis Maria B. Garcia, Yasuaki Takagi
    ICHTHYOLOGICAL RESEARCH 63 (1) 121 - 131 1341-8998 2016/01 [Refereed][Not invited]
     
    The embryonic and larval development of hatchery-reared silver therapon Leiopotherapon plumbeus are described to provide essential information on the early life history of this species. Egg size, larval size at hatching, yolk resorption rate, onset of feeding and development of some morphological characters were examined. Fertilized eggs (430-610 A mu m in diameter) were spherical, yellowish, demersal and slightly adhesive. First cleavage occurred 6 min post-fertilization and embryos hatched 21-24 h post-fertilization under ambient temperature of 27.5 +/- A 0.1 A degrees C. Newly hatched larvae [1.79 +/- A 0.04 mm in total length (TL)] with yolk volume of 0.579 +/- A 0.126 mm(3) had no functional or pigmented eyes, mouth or digestive tract. The eyes became fully pigmented and mouth opened [31 and 36.5 hours post-hatching (hph)] shortly before yolk resorption at 39 hph and when larvae had grown to 2.65 +/- A 0.14 mm in TL. Some morphological characters such as total length, pre-anal length and eye diameter decreased following yolk resorption, which also coincided with the development of foraging capacities shortly before exogenous feeding was initiated. L. plumbeus larvae initiated exogenous feeding at 54 hph, indicating a short (15 h after yolk resorption) transitional feeding period. Larval growth at the early stages of development (54-72 hph) was rapid and steadily increased from 288 to 720 hph, when larvae, 12.05 +/- A 4.02 mm in TL, closely resembled the external characteristics of their adult conspecifics.
  • Heng Wang, Kazuhiro Ura, Yasuaki Takagi
    FISHERIES SCIENCE 81 (6) 1127 - 1134 0919-9268 2015/11 [Refereed][Not invited]
     
    Major yolk protein (MYP) is the most abundant protein found in the yolk granules of sea urchin eggs. The structure of MYPs stored in the eggs of two sea urchin species from Strongylocentrotus intermedius and Mesocentrotus nudus were investigated. Egg-localized major yolk protein (EGMYP) extracted from the eggs of two species of sea urchins was assessed using disc-polyacrylamide gel electrophoresis and immunoelectrophoresis. The molecular weight of native EGMYP was 595 in S. intermedius eggs and 625 kDa in M. nudus eggs. The use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting analysis under reducing conditions revealed that the EGMYP of S. intermedius separated into four bands (approximately 172, 116, 74 and 68 kDa), while the EGMYP of M. nudus resolved as a set of bands ranging from 175 to 58 kDa (approximately 175, 165, 153, 115, 102, 90, 78, 65 and 58 kDa). Yolk granules from eggs were isolated using sucrose density ultracentrifugation and examined using electron microscopy. The structures of purified EGMYP extracted from eggs and from yolk granules were similar in both species. The EGMYP stored in the eggs of the sea urchins was a glycoprotein complex, the protein structure of which, however, varied between the two species.
  • Md. Tariful Islam Mredha, Xi Zhang, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Yasuaki Takagi, Jian Ping Gong
    JOURNAL OF MATERIALS CHEMISTRY B 3 (39) 7658 - 7666 2050-750X 2015 [Refereed][Not invited]
     
    Marine collagen has been attracting attention as a medical material in recent times due to the low risk of pathogen infection compared to animal collagen. Type I collagen extracted from the swim bladder of Bester sturgeon fish has excellent characteristics such as high denaturation temperature, high solubility, low viscosity and an extremely fast rate to form large bundle of fibers under certain conditions. These specific characteristics of swim bladder collagen (SBC) permit us to create stable, disk shaped hydrogels with concentric orientation of collagen fibers by the controlled diffusion of neutral buffer through collagen solution at room temperature. However, traditionally used animal collagens, e.g. calf skin collagen (CSC) and porcine skin collagen (PSC), could not form any stable and oriented structure by this method. The mechanism of the superstructure formation of SBC by a diffusion induced gelation process has been explored. The fast fibrillogenesis rate of SBC causes a quick squeezing out of the solvent from the gel phase to the sol phase during gelation, which builds an internal stress at the gel-sol interface. The tensile stress induces the collagen molecules of the gel phase to align along the gel-sol interface direction to give this concentric ring-shaped orientation pattern. On the other hand, the slow fibrillogenesis rate of animal collagens due to the high viscosity of the solution does not favor the ordered structure formation. The denaturation temperature of SBC increases significantly from 31 degrees C to 43 degrees C after gelation, whereas that of CSC and PSC were found to increase a little. Rheology experiment shows that the SBC gel has storage modulus larger than 15 kPa. The SBC hydrogels with thermal and mechanical stability have potential as bio-materials for tissue engineering applications.
  • Physical-chemical identifier prepared by scallop shell
    Isao Shimono, Shiro Takahashi, Sentaro Mori, Katsuyuki Sato, Junya Kobayashi, Yasuaki Takagi
    Report of the Hokkaido Industrial Technology Center (13) 18 - 25 2014/12 [Not refereed][Not invited]
  • Norihiko Komatsu, Nobuhiro Ogawa, Kurin Iimura, Kazuhiro Ura, Yasuaki Takagi
    FISHERIES SCIENCE 80 (6) 1249 - 1256 0919-9268 2014/11 [Refereed][Not invited]
     
    Fish scales are a potential source of collagen for fabricating scaffolds for cells during tissue engineering because fish collagen has a low risk of zoonosis. Since the assembly of collagen fibrils has a significant impact on the functionality of the scaffold, the ability to replicate the fibril assembly of human tissues is critical. To determine the mechanism of fish collagen fibril assembly, we first identified non-collagenous proteins (NCPs), the potential regulators of fibril assembly in vivo, and then used tandem mass spectrometry to analyze the NCPs contained in the basal plates of goldfish Carassius auratus scales, a collagenous plate which is characterized by a plywood-like assembly of collagen fibrils similar to that found in the cornea. We identified a 19-kDa acidic protein as dermatopontin, the NCP which is a possible regulator of fibril assembly in the mammalian cornea. We cloned a goldfish dermatopontin cDNA of 1,074 bp containing an open reading frame encoding 196 amino acids. Reverse transcription-PCR revealed that dermatopontin mRNA was expressed in a wide range of tissues, including scale, skin, fin, eye, and skeletal muscle. In situ hybridization revealed that dermatopontin mRNA was expressed primarily in the basal plate-producing hyposquamal scleroblasts of the scales, suggesting that the dermatopontin is linked to the collagen fibril assembly of the basal plate.
  • Xi Zhang, Mika Ookawa, Yongkai Tan, Kazuhiro Ura, Shinji Adachi, Yasuaki Takagi
    FOOD CHEMISTRY 160 305 - 312 0308-8146 2014/10 [Refereed][Not invited]
     
    Collagens purified from Bester sturgeon organs were characterised biochemically, and their fibril-forming abilities and fibril morphologies formed in vitro clarified. Yields of collagens were 2.1%, 11.9%, 0.4%, 18.1%, 0.4%, 0.8% and 0.03% (collagen dry weight/tissue wet weight) from scales, skin, muscle, swim bladder, digestive tract, notochord and snout cartilage, respectively. Using SDS-PAGE and amino acid composition analyses, collagens from scales, skin, muscle, the swim bladder and digestive tract were characterised as type I, and collagens from the notochord and snout cartilage as type II. Denaturation temperatures of the collagens, measured using circular dichroism, were 29.6, 26.8, 29.0, 32.9, 31.6 and 36.3 degrees C in scales, skin, muscle, swim bladder, digestive tract, and notochord, respectively. For fibril formation, swim bladder and skin collagen showed a more rapid rate of increase in turbidity, a shorter time to attain the maximum turbidity, and formed thicker fibrils compared with porcine tendon type I collagen. (C) 2014 Elsevier Ltd. All rights reserved.
  • Kenta Susuki, Masaki Ichimura, Yosuke Koshino, Masahide Kaeriyama, Yasuaki Takagi, Shinji Adachi, Hideaki Kudo
    JOURNAL OF MORPHOLOGY 275 (5) 514 - 527 0362-2525 2014/05 [Refereed][Not invited]
     
    Mature male Pacific salmon (Genus Oncorhynchus) develop a dorsal hump, as a secondary male sexual characteristic, during the spawning period. Previous gross anatomical studies have indicated that the dorsal humps of salmon are mainly composed of cartilaginous tissue (Davidson [1935] J Morphol 57:169-183.) However, the histological and biochemical characteristics of such humps are poorly understood. In this study, the detailed microstructures and components of the dorsal humps of pink salmon were analyzed using histochemical techniques and electrophoresis. In mature males, free interneural spines and neural spines were located in a line near to the median septum of the dorsal hump. No cartilaginous tissue was detected within the dorsal hump. Fibrous and mucous connective tissues were mainly found in three regions of the dorsal hump: i) the median septum, ii) the distal region, and iii) the crescent-shaped region. Both the median septum and distal region consisted of connective tissue with a high water content, which contained elastic fibers and hyaluronic acid. It was also demonstrated that the lipid content of the dorsal hump connective tissue was markedly decreased in the mature males compared with the immature and maturing males. Although, the crescent-shaped region of the hump consisted of connective tissue, it did not contain elastic fibers, hyaluronic acid, or lipids. In an ultrastructural examination, it was found that all of the connective tissues in the dorsal hump were composed of collagen fibers. Gel electrophoresis of collagen extracts from these tissues found that the collagen in the dorsal hump is composed of Type I collagen, as is the case in salmon skin. These results indicate that in male pink salmon the dorsal hump is formed as a result of an increase in the amount of connective tissue, rather than cartilage, and the growth of free interneural spines and neural spines. J. Morphol. 275:514-527, 2014. (c) 2013 Wiley Periodicals, Inc.
  • Yongkai Tan, Kurin Iimura, Tetsuro Sato, Kazuhiro Ura, Yasuaki Takagi
    Gene 516 (2) 277 - 284 0378-1119 2013/03/10 [Refereed][Not invited]
     
    There has been significant interest in the expression and function of dermatopontin (DPT) in mammals owing to recent evidence pointing to its critical role in collagen fibrillogenesis. Despite this interest, limited information is available about the site/s of DPT mRNA expression or changes in expression in vivo. We used reverse-transcription polymerase chain reaction and in situ hybridization to evaluate the spatial and temporal pattern of DPT mRNA expression in zebrafish, Danio rerio, a widely used vertebrate model. We observed that DPT transcripts were expressed in zebrafish embryos at all developmental stages in a range of tissues, including the brain and optic neuron cells. Based on our results, we hypothesize that DPT may also play a role in neural functions in vivo. © 2012 Elsevier B.V.
  • X. Zhang, K. Shimoda, K. Ura, S. Adachi, Y. Takagi
    JOURNAL OF FISH BIOLOGY 81 (6) 1985 - 2004 0022-1112 2012/11 [Refereed][Not invited]
     
    In the larval bester, a hybrid sturgeon of beluga Huso huso and sterlet Acipenser ruthenus, development of cartilage around the notochord began 7 days post hatch (dph) (14.0 mm, total length, L-T). The vertebral cartilage develops in the following sequence: basidorsals and basiventrals, neural canals, neural spines and ribs. The development of ribs remained incomplete in the largest specimen (181 dph, 179 mm L-T) that was examined. Endoskeletal development of the fins began 4 dph for the dorsal and anal fins, 6 dph for the pectoral fin and 10 dph for the caudal and pelvic fins. Complete elements of all fins were observed by 91 dph and complete ossification of fin rays was observed by 122 dph in the double-stained specimens. Observation of the histological sections, however, suggested that ossification occurred soon after the formation of the organic matrix in the fin rays. Dorsal scutes were first visible by 25 dph, followed by the lateral and ventral scutes, which were visible by 37 and 44 dph, respectively. The number of scutes was fixed at 44, 59 and 91 dph and ossification was complete by 59 (dorsal) and 91 dph (lateral and ventral scutes) in the double-stained specimens. Ossification occurred soon after the formation of the scute organic matrix in the histological sections. Four types of scales were observed in the H. huso x A. ruthenus hybrid. Median predorsal, preanal and small scales on the anterior section of the head were visible by 59 dph. Scales on the caudal fin were visible by 91 dph and a variable assemblage of scales anterior to the anal fin was visible by 122 dph. Both the scutes and scales developed in a process that is similar to that of intramembranous ossification. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles
  • Syuto Hasegawa, Kazuhiro Ura, Hiroyuki Tanaka, Takao Ojima, Yasuaki Takagi
    FISHERIES SCIENCE 78 (5) 1107 - 1115 0919-9268 2012/09 [Refereed][Not invited]
     
    We isolated a cellulase from the digestive organs of the short-spined sea urchin Strogylocentrotus intermedius using a combination of ion-exchange chromatography and gel filtration together with an assay for carboxymethylcellulase activity. The isolated cellulase was stained as a single band by Congo red. The molecular weight of the isolated cellulase, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, was 59 kDa. The isolated cellulase exhibited hydrolytic activity toward carboxymethyl cellulose, with an optimum temperature and pH of 30 A degrees C and pH 8.0, respectively. The thermal stability of the enzyme was characterized by determining the temperature at which activity decreased by 50 % with treatment for 30 min at pH 7.0 and found to be 32 A degrees C. Cellulase activity remained at a high level at 5-20 A degrees C, which is the growth temperature of the short-spined sea urchin. These results confirm that the short-spined sea urchin should preferably be reared at a water temperature of < 20 A degrees C.
  • George Shigueki Yasui, Takafumi Fujimoto, Lenin Arias-Rodriguez, Yasuaki Takagi, Katsutoshi Arai
    AQUACULTURE 344 147 - 152 0044-8486 2012/05 [Refereed][Not invited]
     
    The solutions commonly used to dilute or cryopreserve sperm are commonly composed of salts, buffers and cryoprotectants, which may affect gametes and subsequent fertilization success. Here, we have evaluated the effects of several cryoprotectants (methanol; MeOH, dimethyl sulfoxide; DMSO and dimethyl acetamide; DMA at concentrations of 0.25, 0.5 and 1%) and different ions (potassium, calcium and magnesium at concentrations of 1.25, 2.5, 5.0 and 10 mM) as sperm diluents upon sperm motility and fertilization success in the loach Misgurnus anguillicaudatus sperm. Our results demonstrated that DMSO (at 1%) decreased sperm motility while calcium and magnesium ions (from 2.5 mM) induced sperm aggregation and reduced sperm motility. Reduced fertilization rates were observed with potassium (from 1.25 mM), calcium (at 10 mM), magnesium (at 10 mM), DMA (at 1%), and DMSO (at 1%). We conclude that specific ions and cryoprotectants, and their relative concentrations caused effect upon loach gametes. These data are important to consider for the preparation of sperm diluents and activating solutions in order to manage gamete quality for artificial propagation. (C) 2012 Elsevier B.V. All rights reserved.
  • Kurin Iimura, Hidekazu Tohse, Kazuhiro Ura, Yasuaki Takagi
    JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 318B (3) 190 - 198 1552-5007 2012/05 [Refereed][Not invited]
     
    Teleost fish scale is a dermal skeleton equipped with a strong regenerative ability. Owing to this regenerative ability, teleost fish scale can be used as a model for the regeneration of the dermal skeleton. However, there is insufficient fundamental knowledge of the regeneration, and this limits the usage of fish scale. In this study, as a first step toward understanding the molecular mechanism of the cellular differentiation during scale regeneration, we cloned the cDNAs for osteoblast-related proteins (Runx2, Sparc, and Bgp) in goldfish, and analyzed their expressions during scale regeneration. The expression profiles of these genes during scale regeneration were similar to those during mammalian osteoblastic differentiation. Specifically, runx2 expression was increased at the earliest time point, followed by sparc expression and then bgp expression. In the earlier stages, these genes were expressed in cells that formed cellular condensations and the flat cells surrounding them in the scale pocket. As the regeneration proceeded, the expressions became restricted to the episquamal, hyposquamal, and marginal scleroblasts and the cells around the marginal area of the regenerating scale. These results strongly suggest that (1) the differentiation mechanism of scleroblasts is similar to that of mammalian osteoblasts and odontoblasts, (2) scleroblast differentiation occurs around the cellular condensations at the early regeneration stage and is restricted to the marginal area of the scale at the later stage, and (3) the differentiation mechanisms are similar between the episquamal scleroblasts that produce the external layer and the hyposquamal scleroblasts that produce the basal plate. J. Exp. Zool. (Mol. Dev. Evol.) 318:190198, 2012. (c) 2012 Wiley Periodicals, Inc.
  • Kazuhiro Ura, Syuto Hasegawa, Eri Tanaka, Takahiro Gotoh, Takao Ojima, Yasuaki Takagi
    ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY 295 (1) 73 - 77 1932-8486 2012/01 [Refereed][Not invited]
     
    Subtilase, a major protease in the short-spined sea urchin (Strongylocentrotus intermedius), was isolated and used as antigen for the subsequent production of a specific polyclonal antibody. Immunoreactive cells were observed by immunohistochemical analysis in granules in the anterior and posterior stomach and the anterior intestine. These granules, which were most numerous in the anterior stomach, also stained intensely with methylene blue-Azure II. However, granules in cells of the esophagus, posterior intestine, and rectum were not stained by this antibody. We conclude that subtilase mainly localizes in the stomach and anterior intestine of the sea urchin. Anat Rec, 2012. (C) 2011 Wiley Periodicals, Inc.
  • Shimono Isao, Shiro Takahashi, Sentaro Mori, Katsuyuki Sato, Junya Kobayashi, Yasuaki Takagi
    Report of the Hokkaido Industrial Technology Center テクノポリス函館技術振興協会 (12) 31 - 37 0917-1851 2012 [Not refereed][Not invited]
     
    ホタテガイ貝殻の利活用は、大量使用の見込める製品(土壌改良材等)の低コスト化と、少量でも付加価値の高い製品の創製というように、目的別に取組むことが望ましい。本研究では、ホタテガイ貝殻から高機能材料を創製することを目的とし、ホタテガイ貝殻が持つ蛍光機能を活かした応用研究を行った。本研究の結果、貝殻製蛍光体の4つの発光帯の強度比は、食品の灰化処理を目的として行なった熱処理に対し、高い安定性を示した。この結果に基づき、ホタテガイ貝殻から創製した貝殻製蛍光体の、発光帯の強度比を識別番号と見なし、これを食品やサプリメントのロット番号や製造年月日等の情報と対応させることで、包装容器と中身との同一性を証明するための目印となる食品用標識剤を提案した。
  • Nobuhiro Ogawa, Kazuhiro Ura, Yasuaki Takagi
    FISHERIES SCIENCE 76 (2) 189 - 198 0919-9268 2010/03 [Refereed][Not invited]
     
    The external layer of a teleost fish scale is composed of type I collagen, an amorphous matrix substance and hydroxyapatite crystals. Calcification of this layer can be inhibited in the scale-regenerating process under calcium-and phosphate-deficient (CaDPD) conditions, and can be facilitated by incubation in physiological saline. The aim of this study was to evaluate this model of calcification using histological and quantitative analysis in order to promote further understanding of the mechanism of calcification in fish scales. We found that the external layer of the scales produced under CaDPD conditions contained more densely aligned collagen fibrils with a small amount of the amorphous matrix substance. The CaDPD scale contained only one-third of the amount of calcium and phosphate present in the control fish. After 4 hours of incubation, a two-to threefold increase in calcium content and a 1.5-fold increase in phosphate content were observed. Calcification proceeded in the external layer, and mineral deposits grew only in the electron-dense matrix substance. We conclude that this model would be suitable for studying the early process of fish scale calcification that occurs in the noncollagenous substance. The electron-dense substance may contain key molecules that promote calcification.
  • Hidekazu Tohse, Kazuko Saruwatari, Toshihiro Kogure, Hiromichi Nagasawa, Yasuaki Takagi
    CRYSTAL GROWTH & DESIGN 9 (11) 4897 - 4901 1528-7483 2009/11 [Refereed][Not invited]
     
    We show that the high-molecular weight (HMW) protein aggregate of fish otolith matrix is involved in the regulation of crystal polymorphs during otolith biomineralization. Teleost fish otoliths are biominerals that contain calcium carbonate aragonite or vaterite crystals. In a previous study, we identified a novel protein named otolith matrix macromolecule-64 (OMM-64) within the otolith organic matrix. In addition, we revealed that the HMW aggregate of otolith matrix architecture was comprised of OMM-64, in which inner-ear-specific short-chain collagen otolin-1 was also contained. By using an in vitro crystallization system in the absence of magnesium ions here, we show that native OMM-64 induced vaterite crystals, whereas native otolion-1 induced calcite crystals. However, the aggregate complex induced the aragonite polymorph ill the same condition. The present data suggest that separation and Structural and functional analyses of each matrix protein ill the aggregate are absolutely imperative, but functional examination of the protein complex itself is equally important in clarifying polymorph control of biomineralization.
  • KOBAYASHI Yutaka, TAKAMURA Takumi, SHIMONO Isao, URA Kazuhiro, TAKAGI Yasuaki
    Aquaculture Science 水産増殖談話会 57 (2) 271 - 278 0371-4217 2009/06 [Refereed][Not invited]
     
    Compositions of the trace elements in bivalve shells and fish otoliths, both of which are made of calcium carbonate crystals, largely reflect those of elements in the environment, and thus, may be "foot prints" of the individuals' environmental life histories. In the present study, the trace elemental compositions of these tissues were applied to the discrimination of production places of the aquacultured scallop Patinopecten yessoensis and rainbow trout Oncorhynchus mykiss. Concentrations of lithium, manganese, strontium and barium in the aquacultured, 2+-year old scallop shells, which were from Otsuchi and Yamada in Iwate prefecture and Shikabe and Shiriuchi in Hokkaido, were measured by inductively coupled plasma mass spectrometry. By MANOVA analysis, the discrimination accuracy was 81.3%; 9 individuals, mostly from Otsuchi, out of 48 ones were mis-discriminated. Similarly, elemental concentrations of the otoliths from Hachimantai in Iwate and Nanae in Hokkaido were quantified. The discrimination accuracy by MANOVA was 95.5%; two individuals out of 44 ones were mis-discriminated. These data suggest that elemental compositions of bivalve shells and fish otoliths are useful keys to estimate their origins in the aquacultured species, although variations of the compositions by the production year should be carefully studied further.
  • Konomi Sakamoto, Wataru Honto, Masaharu Iguchi, Nobuhiro Ogawa, Kazuhiro Ura, Yasuaki Takagi
    Fisheries Science 75 (1) 91 - 98 0919-9268 2009/02 [Refereed][Not invited]
     
    This study examines the following in the Japanese mitten crab: (1) the structure of the exoskeleton with special reference to its calcification (2) the progression of post-molt cuticle formation and calcification. In the crab, the structure and calcification state of the exoskeleton at the molt and during the inter-molt stage were similar to those of other crustaceans. During the inter-molt, the exoskeleton consisted of four cuticle layers the outermost epicuticle, the exocuticle, the endocuticle and the innermost membrane layer. Intense calcification was observed in the exo- and endocuticle. At the molt, the synthesis of the epi- and exocuticle was already complete, and the addition of the endocuticle began after the molt. Calcification of the exocuticle initiated soon after the molt, but there was a delay between endocuticle matrix synthesis and calcification. Histology showed that the process of calcification was similar to that in other crustaceans. However, calcium concentrations within the exoskeleton continued to increase and never reached the levels of the inter-molt stage at the end of the experiment. This suggests that the Japanese mitten crab is relatively slow to calcify compared to other crustaceans. © 2008 The Japanese Society of Fisheries Science.
  • 浦 和寛, 田中 恵梨, 東藤 孝, 後藤 孝弘, 清水 幹博, 尾島 孝男, 都木 靖彰
    Bulletin of fisheries sciences, Hokkaido University 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 58 (3) 21 - 28 1346-1842 2009/02 [Not refereed][Not invited]
     
    We purified a subtilase from digestive system of short spined sea urchin Strongylocentortus intermedius by a combination of ion-exchange chromatography and gel filtration. The molecular weight of purified subtilase on SDS-PAGE under both reducing and nonreducing conditions was 35,000. Antiserum against subtilase specifically immunostained its antigen. By Western blot analysis, immunoreactive with this antibody were observed in stomach and intestine.
  • Hidekazu Tohse, Yasuaki Takagi, Hiromichi Nagasawa
    FEBS JOURNAL 275 (10) 2512 - 2523 1742-464X 2008/05 [Refereed][Not invited]
     
    In the biomineralization processes, proteins are thought to control the polymorphism and morphology of the crystals by forming complexes of structural and mineral-associated proteins. To identify such proteins, we have searched for proteins that may form high-molecular-weight (HMW) aggregates in the matrix of fish otoliths that have aragonite and vaterite as their crystal polymorphs. By screening a cDNA library of the trout inner ear using an antiserum raised against whole otolith matrix, a novel protein, named otolith matrix macromolecule-64 (OMM-64), was identified. The protein was found to have a molecular mass of 64 kDa, and to contain two tandem repeats and a Glu-rich region. The structure of the protein and that of its DNA are similar to those of starmaker, a protein involved in the polymorphism control in the zebrafish otoliths [Sollner C, Burghammer M, Busch-Nentwich E, Berger J, Schwarz H, Riekel C & Nicolson T (2003) Science302, 282-286]. Ca-45 overlay analysis revealed that the Glu-rich region has calcium-binding activity. Combined analysis by western blotting and deglycosylation suggested that OMM-64 is present in an HMW aggregate with heparan sulfate chains. Histological observations revealed that OMM-64 is expressed specifically in otolith matrix-producing cells and deposited onto the otolith. Moreover, the HMW aggregate binds to the inner ear-specific short-chain collagen otolin-1, and the resulting complex forms ring-like structures in the otolith matrix. Overall, OMM-64, by forming a calcium-binding aggregate that binds to otolin-1 and forming matrix protein architectures, may be involved in the control of crystal morphology during otolith biomineralization.
  • Masayuki Iigo, Tomotaka Abe, Saori Kambayashi, Kaoru Oikawa, Tomohiro Masuda, Kanta Mizusawa, Shoji Kitamura, Teruo Azuma, Yasuaki Takagi, Katsumi Aida, Tadashi Yanagisawa
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 154 (1-3) 91 - 97 0016-6480 2007/10 [Refereed][Not invited]
     
    In many teleost species, the photoreceptive pineal organ harbors the circadian clock that regulates melatonin release in the pineal organ itself. However, the pineal organ of three salmonids (rainbow trout Oncorhynchus mykiss, masu salmon Oncorhynchus masou, and sockeye salmon Oncorhynchus nerka) did not exhibit cireadian rhythms in melatonin release when maintained under constant darkness (1313) in vitro, suggesting that the pineal organs of all salmonids lack the circadian regulation of melatonin production. To test this hypothesis, the pineal organ of seven salmonids (common whitefish Coregonus lavaretus, grayling Thymallus thymallus, Japanese huchen Hucho perryi, Japanese charr Salvelius leucomaenis pluvius, brook trout Salvelius fontinalis, brown trout Salmo trutta and chum salmon Oncorhynchus keta) and closely related osmerids (ayu Plecoglossus altivelis altivelis and Japanese smelt Hypomesus nipponensis) were individually maintained in flow-through culture at 15 degrees C under several light conditions. Under light-dark cycles, the pineal organ of all species showed a rhythmic melatonin release with high rates during the dark phase. Under DD, the osmerid pineal organs exhibited circadian rhythms in melatonin release with high rates only during the subjective-night but the salmonid pineal organs constantly released melatonin at high rates. Under constant light, melatonin release was suppressed in all species. The pineal organ of rainbow trout maintained at different temperature (15, 20 or 25 degrees C under DD released melatonin with high rates but the amount of melatonin released was temperature-sensitive (highest at 20 degrees C). Thus, melatonin release from the pineal organ of osmerids is regulated by both light and circadian clock but the circadian regulation is lacking in salmonids. These results indicate that ancestral salmonids lost the circadian regulation of melatonin production after the divergence from osmerid teleosts. (C) 2007 Elsevier Inc. All rights reserved.
  • Yasuaki Takagi, Kazuhiro Ura
    Journal of Nanoscience and Nanotechnology 7 (3) 757 - 762 1533-4880 2007/03/01 [Refereed][Not invited]
     
    The corneal stroma is composed of multiple lamellae, each containing closely packed collagen fibrils. The orientation of fibrils in a lamella is parallel, but those in different lamellae are orthogonal. As a result, the corneal stroma has a characteristic orthogonal plywood-like structure. Such a highly-regulated three-dimensional arrangement of collagen fibrils gives strength and transparency to the corneal stroma, but it also presents a challenge in the fabrication of materials to replace it. A bioinspired technology is required to process such materials, but the regulatory mechanism of collagen-fibril orientation is still unknown. The low regenerating activity of the corneal stroma seems to be a major factor preventing progress in this field of research. A similarly highly-ordered arrangement of collagen fibrils can be seen in the basal plates of teleost fish scales. Moreover, the scales have high regenerating ability. When a scale is mechanically lost, a new scale is rapidly regenerated. The cells that produce the basal plates are extremely activated; thus, production of the highly-ordered collagen fibrils is very rapid. Therefore, the regenerating scales should be a uniquely helpful biological model for studying the regulatory mechanism of collagen-fibril orientation. Fish-scale collagen has another advantage for use as a biomaterial: the low probability of zoonotic infection. Therefore, scale collagen is a most promising biomaterial for fabricating three-dimensionally arranged collagen fibers to substitute for the corneal stroma. Three tasks that must be clarified for the bioinspired production of a corneal substitute from fish scale collagen are proposed.
  • Takaomi Arai, Takafumi Hirata, Yasuaki Takagi
    MARINE ENVIRONMENTAL RESEARCH 63 (1) 55 - 66 0141-1136 2007/02 [Refereed][Not invited]
     
    Trace element levels in otoliths of chum salmon Oncorhynchus keta were examined by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). A close linear relationship in the Sr:Ca ratios between EPMA (X-ray analysis with an electron microprobe) and LA-ICPMS analyses was found (p < 0.0001), suggesting that the latter technique could be used to separate the marine and freshwater life phases. Mg:Ca, Cr:Ca, Zn:Ca and Ba:Ca ratios in either the core region or the oceanic growth zone of the otoliths varied among sites. These differences suggest that elemental compositions may reflect environmental variability among spawning (breeding) or habitat sites. Thus, those element ratios demonstrate the potential to be used to distinguish between fish spawning (breeding) sites and habitats for this species of salmon. (c) 2006 Elsevier Ltd. All rights reserved.
  • Yasuharu Ohira, Motohiro Shimizu, Kazuhiro Ura, Yasuaki Takagi
    FISHERIES SCIENCE 73 (1) 46 - 54 0919-9268 2007/02 [Refereed][Not invited]
     
    The time-course changes in calcium and phosphorus contents, dry weight, and area during scale regeneration in the goldfish Carassius auratus L. were quantified. Histological observations were then conducted to understand the mutual relationship between the quantitative and morphological processes of scale regeneration. The quantitative study revealed that regenerating scales grow most rapidly in area during the first 5 days of regeneration. The gradual decrease in the area growth rate coupled with the continuous linear weight growth over the period of 5-28 days suggests a shift in growth priority from area growth to the apposition of the basal plate. Calcium and phosphorus deposition proceeded almost linearly during scale regeneration. Calcification of the bony layer preceded that of the basal plate and, after 14 days of regeneration, calcification of the basal plate started and gradually progressed. On day 28, recovery of calcium and phosphorus contents in the regenerating scales were approximatley 72% of ontogenetic scales, which is lower than the rates of area and weight regeneration (104 and 85%, respectively). Late initiation and slow progress of calcification in the basal plate is suggested to be responsible for the slow regeneration in calcium and phosphorus contents.
  • Hidekazu Tohse, Emi Murayama, Tsuyoshi Ohira, Yasuaki Takagi, Hiromichi Nagasawa
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY 145 (3-4) 257 - 264 1096-4959 2006/11 [Refereed][Not invited]
     
    Physiological studies have suggested that carbonic anhydrase (CA) plays a central role in otolith biomineralization via ion transport. However, the presence and exact function of CA in the inner ear have not been determined. In the present study, to investigate the localization of CA and its involvement in otolith calcification, we cloned two cDNAs encoding CAs from the rainbow trout sacculus. These two cDNAs, designated rainbow trout CAa (rtCAa) and rtCAb, both had an open reading frame encoding 260 amino acids with a sequence identity of 78%. Remarkably, rtCAb has a high degree of homology (82%) with "high activity CA" in the zebrafish, and its mRNA expression showed variation in the range 1.9-11.4 x 10(4) copies/ng total RNA in the sacculus. In contrast, rtCAa mRNA was constantly expressed at approximately 3 x 10(4) copies/ng total RNA. In situ hybridization revealed that rtCAb mRNA was strongly expressed in the distal squamous epithelial cells and transitional epithelial cells, except the mitochondria-rich cells, whereas, rtCAa was localized in extrasaccular tissue. These results suggest that the rtCAb isozyme is involved in the daily increment formation and calcification of otoliths via phase and spatial differences of the bicarbonate supply to the endolymph. (c) 2006 Elsevier Inc. All rights reserved.
  • Yoshifumi Sawada, Manabu Hattori, Naoko Sudo, Keitaro Kato, Yasuaki Takagi, Kazuhiro Ura, Michio Kurata, Tokihiko Okada, Hidemi Kumai
    Aquaculture Research 37 (8) 805 - 812 1355-557X 2006/06 [Refereed][Not invited]
     
    A previous study elucidated that an extreme hypoxia during somitogenesis induced the most frequent skeletal malformation centrum defects in red sea bream (RSB), Pagrus major. In this study, details of the hypoxic conditions to induce them in RSB, dissolved oxygen (DO) concentration and exposure time to hypoxia, were investigated. Fertilized eggs were exposed to seawater of six DO concentrations (0%, 10%, 25%, 50%, 75% and 100% of saturation) for seven different periods (5, 10, 30, 60, 120, 240 and 360 min) during somitogenesis. Somitic disturbances in newly hatched larvae were induced by exposure to 0% and 10% DO concentration for 10 and 120 min and longer respectively. Rearing eggs exposed to hypoxic condition of 10% DO for 240 min for 40 days post-hatch showed that the location and the frequency of somitic disturbances in larvae and centrum defects in juveniles were significantly correlated (P< 0.01). Dissolved oxygen concentration of the interstitial water in the egg high density layer formed at the water surface in a stationary state abruptly decreased to 3.7% within 7 min. Centrum defect induction by exposure of eggs to extreme low DO concentrations for a short period, which is the probable situation in the practical juvenile production, suggests that careful maintenance of DO concentration is important in the incubating water of fertilized eggs during egg sorting and transportation, where eggs are made into a pile and undergo hypoxia, for the prevention of centrum defects. © 2006 Blackwell Publishing Ltd.
  • Induction of centrum defects in amberjack, Seriola dumerili, by exposure of embryos to hypoxia.
    Sawada Y, Hattori M, Iteya M, Takagi Y, Ura K, Seoka M, Kato K, Kurata M, Miyatake H, Katayama A, Kumai H
    Fisheries Science 72 364 - 372 2006/03 [Refereed][Not invited]
  • Isao Shimono, Takumi Takamura, Chiyoko Hosaka, Junya Kobayashi, Yasuaki Takagi, Hajime Yamamoto
    Journal of the Ceramic Society of Japan 社団法人日本セラミックス協会 114 (1328) 341 - 346 1348-6535 2006 [Not refereed][Not invited]
     
    We studied new preparation conditions for scallop shell phosphors to suppress weathering and the disappearance of fluorescence, and measured the fluorescence properties of these phosphors. When a shell was fired to 900°C in a carbon dioxide atmosphere, weathering and the disappearance of fluorescence could be suppressed. It was found that the higher brightness of the shell phosphor fired at 860°C was about 6cd/m2, when the power of irradiated UV light was about 1.6 W/m2. The emission spectrum shows three bands, with peaks at about 420 nm, 485 nm and 585 nm. The bands at 420 nm and 485 nm are presumed to be due to Cu, and the band at 585 nm is presumed to be due to Mn.
  • Hiroaki Yoshikubo, Nobuo Suzuki, Keiju Takemura, Masahiro Hoso, Sayaka Yashima, Shawichi Iwamuro, Yasuaki Takagi, Makoto J. Tabata, Atsuhiko Hattori
    Life Sciences 76 (23) 2699 - 2709 0024-3205 2005/04/22 [Refereed][Not invited]
     
    Osteogenesis in the teleost was morphologically observed using regenerating scales of goldfish. Histological observations indicated that osteoblasts around the regenerating scales on days 7 to 10 were greater in size and number than those at other stages. Therefore, further experiments were carried out to examine the activity of osteoblasts in the regenerating period. To quantify their osteoblastic activities, scales on the left side of the body were taken, and the regenerating scales were then used to measure the activities of alkaline phosphatase (ALP), a marker of osteoblasts, on days 7, 10, and 15. The ontogenic scales on the right side of the body were also collected and used to measure ALP activity on the same days. Osteoblasts at all stages of regenerating scales were more active than those in the remaining ontogenic scales. The regenerating scales on day 10 had the highest activity. Furthermore, we found that estrogen receptor (ER) mRNA was expressed in the regenerating scales because estrogen participates in osteoblastic growth and differentiation in mammals. Therefore, using a scale culture system reported previously, the estrogenic response was examined in the ontogenic and regenerating scales on day 10. The reactivity was much higher in regenerating scales, although estrogen treatment significantly activated the osteoblastic activities in both scales. We are the first to demonstrate that ER is expressed in regenerating scales and that estrogen participates in osteogenesis as it does in mammalian bone. Our findings strongly suggest that regenerating scales can be used as a model of osteogenesis in vertebrates. © 2005 Elsevier Inc. All rights reserved.
  • Y Takagi, H Tohse, E Murayama, T Ohira, H Nagasawa
    MARINE ECOLOGY PROGRESS SERIES 294 249 - 256 0171-8630 2005 [Refereed][Not invited]
     
    In the teleost fish otolith, the alternate deposition of CaCO3-rich and protein-rich layers results in the formation of daily increments. In order to clarify the mechanism of daily increment formation, a precise understanding of the relationship between ionic and organic controls of otolith growth is essential. In the present study, we studied diel variations in the aragonite saturation rate (Sa) of the endolymph and the mRNA expression of 2 major otolith matrix proteins, OMP-1 and otolin1, in the saccular tissue. A new technique for simultaneously quantifying endolymph S,, and mRNA expression in the saccular tissue from an individual rainbow trout was developed. Endolymph Ca2+ levels, CO2 partial pressure (P-CO2) and pH were simultaneously measured using an automatic pH/gas/electrolyte analyzer, and the S. was calculated.. Total RNA was isolated from sacculi of individual fish after the endolymph was obtained. cDNAs were synthesized and used to quantify OMP-1 and otolin-1 mRNA expression levels by real-time PCR. Significant diel variations were observed in endolymph pH and P-CO2 levels in an antiphasic manner. Endolymph S, did not exhibit significant diel variations and was maintained at a value of more than 2.0, indicating that the endolymph was kept supersaturated with respect to aragonite during the day-night cycle. Expression of otolin-1 mRNA had apparent diel variations with high levels at night, whereas that of OMP-1 mRNA was almost constant. These data strongly suggest an organic control of daily increment formation in the otolith. The most probable candidate protein for daily increment formation is otolin-1.
  • Hirotoshi ENDO, Yasuaki TAKAGI, Noriaki OZAKI, Toshihiro KOGURE, Toshiki WATANABE
    Biochemical Journal 384 (1) 159 - 167 0264-6021 2004/11/15 [Refereed][Not invited]
     
    The DD4 mRNA of the penaeid prawn Penaeus japonicus was shown previously to be expressed in the epidermis adjacent to the exoskeleton specifically during the post-moult period, when calcification of the exoskeleton took place. The encoded protein possessed a Ca2+-binding site, suggesting its involvement in the calcification of the exoskeleton. In the present study, an additional ORF (open reading frame) of 289 amino acids was identified at the 5′ end of the previous ORF. The newly identified part of the encoded protein included a region of approx. 120 amino acids that was highly rich in glutamate residues, and contained one or more Ca2+-binding sites. In an immunohistochemical study, signals were detected within calcified regions in the endocuticular layer of the exoskeleton. Bacterially expressed partial segments of the protein induced CaCO3 crystallization in vitro. Finally, a reverse transcription-PCR study showed that the expression was limited to an early part of the post-moult period, preceding significant calcification of the exoskeleton. These observations argue for the possibility that the encoded protein, renamed crustocalcin (CCN), promotes formation of CaCO3 crystals in the exoskeleton by inducing nucleation.
  • E Murayama, Y Takagi, H Nagasawa
    HISTOCHEMISTRY AND CELL BIOLOGY 121 (2) 155 - 166 0948-6143 2004/02 [Refereed][Not invited]
     
    The fish otolith consists mainly of calcium carbonate and organic matrices, the latter of which may play important roles in the process of otolith formation. We previously identified two otolith matrix proteins, named otolith matrix protein-1 (OMP-1) and otolin-1, from the rainbow trout, Oncorhynchus mykiss, and the chum salmon, O. keta. In this study, recombinant proteins corresponding to OMP-1 and otolin-1 were synthesized using yeast and bacterial expression systems, respectively, to produce specific antibodies against each protein. Immunohistochemical analysis using these antisera revealed that in the otoliths of adult fish, OMP-1 and otolin-1 were colocalized along the daily rings possibly formed by alternate deposition of calcium carbonate and organic matrices. In the adult inner ear, OMP-1 was produced at most of the saccular epithelium, while otolin-1 was produced at a limited part of cylindrical cells located at the marginal zone of the sensory epithelium. In the embryonic inner ear, these proteins had already existed in the otolith primordia when calcification had commenced. In addition, otolin-1 was localized in the fibrous materials connecting otolith primordia and sensory epithelium at this stage. These results indicate that these proteins are required as essential components for otolith formation and calcification.
  • Vertebral deformities in cultured red sea bream, Pagrus major, Temminck and Schlegel.
    Hattori, M, Y. Sawada, Y. Takagi, R. Suzuki, T. Okada, H. Kumai
    Aquaculture Research 34 1129 - 1137 2003/10/10 [Refereed][Not invited]
  • Okada N, Takagi Y, Tanaka M, Tagawa M
    The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology 1 273 (1) 663 - 668 1552-4884 2003/07 [Refereed][Not invited]
  • Takagi Yasuaki, Tanaka Hideji, Naito Yasuhiko
    Otsuchi Marine Science Otsuchi Marine Research Center, Ocean Research Institute, the University of Tokyo 28 6 - 13 1344-8420 2003/03/28 [Refereed][Not invited]
     
    The homing season of chum salmon in the Sanriku coastal area is generally late September to January. The surface water temperature is 20℃ at the beginning of the season and decreases to 12℃ at the end. This temperature condition is very tough for the homing migration of chum salmon, since they are typical cold-water species. How do they behave in the waters where temperatures can be close to their upper lethal limit? We monitored swimming behavior of salmon using micro data-loggers to study the relationship between homing behavior and ambient temperature. Seasonal changes in seawater temperature transformed the salmon behavior from deep diving to surface swimming. The deep diving is a type of behavioral thermoregulation in thermally stratified water with high surface temperature, whereas surface swimming helps the salmon to locate their natal rivers. Sexual maturation induced the salmon to seek their natal river in the surface water, even if their temperature was high. An analysis of the vertical movements of the salmon indicated that salmon are negatively buoyant throughout the dive, and thus, the energy cost for deep diving cannot be negligible. Our data indicate the high behavioral adaptability of salmon to such thermally stratified water with high surface temperature.
  • Yasuaki Takagi
    Marine Ecology Progress Series 231 237 - 245 0171-8630 2002/04/22 [Refereed][Not invited]
     
    This is the first report on the aragonite saturation state of the endolymph in a single fish species, the rainbow trout Oncorhynchus mykiss, based on the direct quantification of electrolyte concentrations in the saccular endolymph. The Ca2+ level, CO2 partial pressure and pH of the saccular endolymph in 1+ and 2+ yr old trout were simultaneously determined using an automatic pH/blood gas/electrolyte analyzer. From the values of CO2 partial pressure and pH, HCO3 - and CO3 2- levels were obtained using the Henderson-Hasselbalch equation. In addition, Na, K, Cl, Mg and inorganic P levels were measured in order to determine ionic strength of the endolymph. The aragonite supersaturation rate (Sa) was calculated from the Ca2+ and CO3 2- concentrations and the ionic strength. In both age groups, Ca2+ and CO3 2- concentrations were around 0.75 and 0.68 mmol l-1, respectively. Small differences in Na, P, and HCO3 - concentrations were observed between the 2 age groups, but endolymph ionic strength was similar. The Sa ratio was 2.885 to 3.507 in 1+ yr old fish and 2.027 to 4.303 in 2+ yr old fish. Therefore, the endolymphis supersaturated with respect to aragonite. Sa was significantly correlated with CO3 2- levels, which were largely determined by pH. As a consequence, Sa was strongly dependent on pH, indicating that endolymph pH-regulation is important in the aragonite crystallization of the otolith.
  • E Murayama, Y Takagi, T Ohira, JG Davis, MI Greene, H Nagasawa
    EUROPEAN JOURNAL OF BIOCHEMISTRY 269 (2) 688 - 696 0014-2956 2002/01 [Refereed][Not invited]
     
    A collagen-like protein was identified from the otoliths of the chum salmon, Oncorhynchus keta. The otolith, composed mainly of calcium carbonate with small amount of organic matrices, is formed in the inner ear and serves as a part of the hearing and balance systems. Although the organic matrices may play important roles in the growth of otolith, little is known about their chemical nature and physiological function. In this study, a major organic component of the otolith, designated otolin-1, which may serve as a template for calcification, was purified. The sequences of two tryptic peptides from otolin-1 revealed high homology with parts of a saccular collagen which had been described previously [Davis, J.G., Oberholtzer, J.C., Burns, F.R. & Greene, M.I. (1995) Science 267, 1031-1034]. Cloning of a cDNA coding for otolin-1 revealed that the deduced amino-acid sequence contained a collagenous domain in the central part of the protein. Although collagen is the most abundant structural protein in the animal body, otolin-1 mRNA was expressed specifically in the sacculus. Immunohistochemical studies showed that otolin-1 is synthesized in the transitional epithelium and transferred to the otolith and otolithic membrane. This is the first report concerning characterization of a structural protein containing many tandem repeats of the sequence, Gly-Xaa-Yaa, typical for collagen from the biomineral composed of calcium carbonate.
  • Yasuaki Takagi
    Zoological Science 18 (5) 623 - 629 0289-0003 2001/07 [Refereed][Not invited]
     
    Fish undergo a brief growth spurt known as "compensatory growth" when they resume adequate feeding after a restricted food intake. In the present study, changes in formation and resorption of acellular bone during the compensatory growth period were quantified using bone histomorphometry. Juvenile tilapia (Oreochromis niloticus) were starved for 15 days and subsequently refed for 15 days. In the starvation period, osteoblastic activity decreased linearly with time and almost reached zero on day 15, whereas the significant reduction in osteoclastic activity first became evident on day 15. This resulted in an increased percentage of eroded bone surface, which is the bone surface affected by osteoclasts. In the refeeding period, osteoblastic activity recovered to the levels of fed fish on day 3, briefly increased above the levels of fed fish on day 7, then returned to those of fed fish on day 15. Osteoclastic activity gradually increased and returned to the levels of fed fish from 7 days onwards. The eroded surface rapidly decreased to the levels of fed fish on day 3, became significantly lower than those of fed fish on day 7, and then returned to those of fed fish on day 15. It is concluded that starvation leads to a decreased turnover rate in tilapia acellular bone, which can be reversed by subsequent refeeding. A brief increase in bone-forming activity above the levels of fed fish, "the compensatory bone-formation", is a characteristic feature of the recovery period.
  • 都木 靖彰, 宮崎 信之
    地球環境 国際環境研究協会 6 (1) 87 - 91 1342-226X 2001 [Not refereed][Not invited]
  • 都木 靖彰, 乙部 弘隆, 田中 秀二
    地球環境 国際環境研究協会 6 (1) 69 - 77 1342-226X 2001 [Not refereed][Not invited]
  • F. Katoh, S. Hasegawa, J. Kita, Y. Takagi, T. Kaneko
    Canadian Journal of Zoology 79 (5) 822 - 829 0008-4301 2001 [Refereed][Not invited]
     
    Physiological and morphological differences between killifish adapted to seawater (SW) and fresh water (FW) were examined with special reference to chloride cells. There was no difference in plasma osmolality between SW- and FW-adapted fish, reflecting their euryhalinity. A rich population of chloride cells was detected in whole-mount preparations of the gills and opercular membrane from SW- and FW-adapted fish. There was no difference between SW- and FW-adapted fish in gill Na+,K+-ATPase activity or oxygen-consumption rates. The gill chloride cells were located mostly in a flat region of the afferent-vascular edge of the filaments. In both tissues, the cells were larger in FW- than in SW-adapted fish. The apical membrane of chloride cells was invaginated to form a pit in SW-adapted fish, whereas it was flat or showed projections and was equipped with microvilli in FW-adapted fish. Chloride cells often interdigitated with neighboring accessory cells in SW-adapted fish, forming multicellular complexes. In FW-adapted fish, on the other hand, a pair of chloride cells that were similar in size was occasionally associated to form "twin cells." Thus, distinct SW and FW types of chloride cells were defined. Our findings suggest that SW- and FW-type chloride cells are equally active in the two environments, but exhibit different ion-transporting functions.
  • Hideji Tanaka, Yasuaki Takagi, Yasuhiko Naito
    Journal of Experimental Biology 204 (22) 3895 - 3904 0022-0949 2001 [Refereed][Not invited]
     
    Although the homing migration of Pacific salmon is well documented, the swimming behaviour of the returning salmon has been poorly described, principally as a result of the difficulties encountered in monitoring salmon behaviour in the sea. The present study describes the use of a recently developed electronic data logger to obtain simultaneous recordings of the swimming speed, depth, fin-beating activity and body angle of free-ranging chum salmon Oncorhynchus keta during their homing migration in coastal waters. Chum salmon migrated horizontally at speeds of 1.5-3.0 km h-1. The gross horizontal distance salmon moved during total recording periods were 1.24- to 19.0-fold greater than the net distance from the release site to the retrieval points. It is suggested that homing salmon did not drift passively but swam actively to the spawning grounds. Salmon preferred the surface water, but also made frequent vertical migrations. The travelled depth of each salmon ranged from 0.36 to 0.64 km per hour. Salmon descended at faster rates and steeper angles than they ascended. Both tailbeat frequency and tail thrust were higher during the ascent than the descent phase. These results suggest that chum salmon spent more energy during the ascent than the descent phase. Profiles of descent rate assumed an arched shape with respect to a change in hydrostatic pressure, while ascent rate increased with decreasing depth. High tailbeat frequencies were found during the course of ascent, which suggests that the salmon did not regulate the volume of air in the swim bladder during short-term vertical migrations.
  • Nozomi Okada, Yasuaki Takagi, Tadahisa Seikai, Masaru Tanaka, Masatomo Tagawa
    Cell and Tissue Research 304 (1) 59 - 66 0302-766X 2001 [Refereed][Not invited]
     
    The symmetrical body of flatfish larvae dramatically changes into an asymmetrical form after metamorphosis. Eye migration results in the most significant asymmetrical development seen in any vertebrate. To understand the mechanisms involved in eye migration, bone and cartilage formation was observed during metamorphosis in laboratory-reared Japanese flounder, Paralichthys olivaceus, by using whole-body samples and histological sections. Most of the hard tissues of the cranium (parasphenoid, trabecular cartilage, supraorbital canal, and supraorbital bar) exist symmetrically in the larval period before metamorphosis and develop by twisting in the same direction as that in which the eye migrates. An increase in skin thickness beneath the eye was observed only on the blind side at the beginning of eye migration this was the first definitive difference between the right and left sides of the body. The pseudomesial bar, a peculiar bone present only in flatfishes, developed from this thick skin and grew dorsad. Novel sac-like structures were found and named retrorbital vesicles. The retrorbital vesicle of the blind side grew larger and faster than that of the ocular side when the right eye moved most dramatically, whereas no difference was observed between the volume of right and left connective tissue in the head. The asymmetrical presence and growth of the pseudomesial bar together with inflation of the retrorbital vesicle on the blind side may be responsible for right eye migration during metamorphosis in the Japanese flounder.
  • T. Yada, T. Azuma, Y. Takagi
    Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 129 (2-3) 695 - 701 1096-4959 2001 [Refereed][Not invited]
     
    The influence of acclimation to seawater (SW) and growth hormone (GH) administration on immune functions was examined in the rainbow trout (Oncorhynchus mykiss). After 3 days acclimation to dilute SW (12 parts per thousand, ppt), an increase in plasma lysozyme activity was observed compared to the fish kept in fresh water (FW). No change was seen in plasma immunoglobulin M (IgM) levels. When they were transferred from dilute SW to full-strength SW (29 ppt) after a single intra-peritoneal injection of ovine or salmon GH, plasma sodium levels of GH-treated fish were significantly lower than those of the control fish injected with Ringer's solution 24 h after the transfer. The plasma level of IgM was not influenced by GH injection in the fish kept in FW nor in those transferred to SW. The administration of GH increased plasma lysozyme activity in the fish in FW, but no further increase was seen after SW transfer. The production of superoxide anions in peripheral blood leucocytes was stimulated by GH in both FW and SW. These results suggest that GH is involved in the stimulation of the non-specific immune functions in SW-acclimated salmonids. © 2001 Elsevier Science Inc.
  • Emi Murayama, Atsuro Okuno, Tsuyoshi Ohira, Yasuaki Takagi, Hiromichi Nagasawa
    Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology 126 (4) 511 - 520 1096-4959 2000/08 [Refereed][Not invited]
  • H Otobe, Y Takagi, A Anbo
    NIPPON SUISAN GAKKAISHI 公益社団法人日本水産学会 66 (4) 705 - 712 0021-5392 2000/07 [Refereed][Not invited]
     
    The relationship between daily salmon catch and sea and weather conditions in Otsuchi Bay located at the center of the Sanriku Coast was analyzed in 1996 and 1997. The daily salmon catch reached a peak when the sea water temperature reached 13 degrees C level in both years. In 80% of cases, the salmon catch at the day after a rainfall (>5 mm) or strong westerly wind (>10 m/s) rose to over 1.5 times that of the previous day. The largest salmon catch of each year was observed to be on the day after the largest precipitation or the longest strong westerly wind. These data suggest that the homing behavior of chum salmon was affected significantly by sea water temperature, rainfall and westerly wind on the Sanriku Coast.
  • Hideji Tanaka, Yasuaki Takagi, Yasuhiko Naito
    Journal of Experimental Biology 203 (12) 1825 - 1833 0022-0949 2000/06 [Refereed][Not invited]
     
    Homing Pacific salmon are suggested to utilise directional cues in shallow water while migrating in coastal waters. Since salmonids are typical cold-water fish, they may have to cope with warm surface water while gathering directional information. We studied behavioural thermoregulation of 31 free-ranging chum salmon Oncorhynchus keta using micro data loggers off the Sanriku coast from early October to December. The surface water temperature was approximately 20°C in early October and decreased to approximately 12°C in December. The seasonal change of water temperature transformed the behaviour of salmon markedly from deep diving to shallow swimming. In October, salmon frequently dived to depths exceeding 100 m. Duration of deep dives tended to be prolonged as the thermal difference between sea surface and bottom water increased. The results indicated that salmon sought the coolest thermal refuge that they could exploit by vertical movement. Thermal refuge could be a way for salmon to minimise metabolic energy cost however, salmon repeatedly returned to the surface water column. We found a positive correlation between surface swimming of salmon and the presence of cool covering water, which could contain river waters. This suggests that salmon tend to be risk-prone when subjected to a high concentration of directional cues. Salmon in December spent most of their time in shallow water. These findings suggest that salmon adjusted their behavioural strategy with the hydrographic structure of the sea in order to achieve a balance between acquiring directional cues and behavioural thermoregulation.
  • Y Takagi, K Ishii, N Ozaki, H Nagasawa
    ZOOLOGICAL SCIENCE 17 (2) 179 - 184 0289-0003 2000/03 [Refereed][Not invited]
     
    Gastrolith matrix protein (GAMP) is a novel protein purified from gastroliths of the crayfish, Procambarus clarkii, and has been suggested to be associated with calcium carbonate deposition. In the present study, a specific antibody against CAMP was raised and distribution of CAMP immunoreactivity was studied in crayfish gastrolith and exoskeleton. Localization of calcium carbonate in the exoskeleton, determined by silver nitrate staining and energy dispersive X-ray microanalysis, was compared with that of GAMP immunoreactivity. Crystalline forms of calcium carbonate were also determined. SDS-PAGE and Western blotting revealed that the gastrolith extract contained a major band which was GAMP-immunopositive and showed the same mobility as that of purified CAMP. The exoskeleton extract showed smear bands, but no immunoreaction was detected. By using immunohistochemistry, the anti-CAMP antiserum reacted almost uniformly with gastrolith matrix irrespective of gastrolith size. Epithelial cells of the gastrolith disc were also immunopositive. In the exoskeleton, exocuticle was strongly CAMP-immunopositive, whereas the endocuticle and membrane layer was slightly positive. The epicuticle was immunonegative. Calcium carbonate was detected in exocuticle, endocuticle and a part of the membrane layer, but not in the epicuticle. Thus, the distribution of CAMP immunoreactivity roughly corresponded with that of calcium carbonate. X-ray diffraction study showed that calcium carbonate in the gastrolith was amorphous, whereas that in the exoskeleton consisted of calcite crystals. These data indicate that a GAMP-immunoreactive substance is commonly distributed in the mineralized tissues of the crayfish, but may exist in a chemically different form in other tissues.
  • Takagi Yasuaki
    Otsuchi marine science The University of Tokyo 25 1 - 6 1344-8420 2000/03 [Refereed][Not invited]
  • Yasuaki Takagi, Kou Ishida, Yasuo Mugiya
    Fisheries Science 66 (5) 933 - 939 0919-9268 2000 [Refereed][Not invited]
     
    A lectin-binding assay was applied to the rainbow trout, Oncorhynchus mykiss, sacculus in order to identify specific sugars in the otolith organ. The binding of biotinylated lectins to the sagitta, otolith membrane and saccular epithelial cells was detected by histochemistry, and their binding to the EDTA-soluble fraction of the otolith matrix and saccular endolymph was detected by dot-blot analysis. N-Acetylglucosamine (GlcNAc) and mannose (Man) were identified in the otolith matrix with both techniques. These data indicate that glycoproteins in the otolith matrix have N-glycosidically linked sugar chains. In the otolith membrane, GlcNAc and Man were identified in the subcupular meshwork, whereas only Man was identified in the gelatinous layer. This is in line with the hypothesis that a part of the subcupular meshwork is incorporated into the otolith as an organic matrix. The saccular epithelial cells reacted with at least one of the lectins which bound to the otolith matrix. The endolymph had the same reactivity with lectins as the otolith matrix. Thus, we suggest that otolith-matrix carbohydrates are produced in the saccular epithelial cells, secreted into the endolymph, and deposited onto the otolith.
  • Yasuaki Takagi
    Fisheries Science 66 (1) 71 - 77 0919-9268 2000 [Refereed][Not invited]
     
    In order to investigate the process of otolith-matrix production and deposition, ultrastructural immunolocalization of an EDTA-soluble fraction of otolith matrix (otolith soluble-matrix, OSM) was studied in the sacculus of rainbow trout, Oncorhynchus mykiss, just-hatched fry. In the transitional epithelial cells of a cylindrical type, OSM was packed in the vesicles whose diameter was 100-250 nm. In the transitional epithelial cells of a cuboidal type and squamous epithelial cells, OSM was packed into the vesicles whose diameter was 0.5-1.5 μm. Sensory epithelium was immunonegative. Exocytosis of small vesicles, dilations of translucent vesicles, and extrusions of cytoplasm were frequently associated with the apical surface of the transitional and squamous epithelial cells. The OSM-immunopositive fibrous substance existed in the endolymph and was deposited onto the otolith surface. Otolith matrix was an OSM-immunopositive fibrous substance arranged into the meshwork. Densely packed layers and less densely packed layers of the matrix were deposited alternatively. The present results indicate that OSM is produced in the transitional and squamous epithelial cells, is stored in the two types of secretory granules, is secreted into the endolymph, and is deposited onto the otolith surface.
  • TSUTSUI Naoaki, ISHII Katsuaki, TAKAGI Yasuaki, WATANABE Toshiki, NAGASAWA Hiromichi
    ZOOLOGICAL SCIENCE 社団法人 日本動物学会 16 (4) 619 - 628 0289-0003 1999/08/15 [Refereed][Not invited]
     
    In the crayfish Procambarus clarkii, the gastroliths are formed as a paired structure in the stomach during the premolt period, and contain calcium carbonate and a small amount of an organic matrix. In this investigation, a cDNA encoding an insoluble matrix protein was isolated from P. clarkii. The open reading frame encoded 505 amino acid residues including two unique repeated sequences. The N-terminal half of the amino acid sequence, which included 10-amino-acid repeats, exhibited a high degree of similarity to that of involucrin, a protein synthesized in human keratinocytes. Northern blot analysis revealed that mRNA encoding the matrix protein is specifically expressed in the gastrolith discs during the premolt period in which the gastroliths formed. In the gastrolith discs, levels of expression of this mRNA correlated increases in weights of the gastroliths concomitant with their formation. Organ culture of the gastrolith discs suggested that expression of mRNA in the discs is induced by molting hormone, 20-hydroxyecdysone. These results reinforced the relationship between the matrix protein and formation of the gastroliths. Functional analysis showed that the protein inhibits calcium carbonate crystallization in a solution system, suggesting that the protein plays a role in the calcification of the gastroliths.
  • P. Persson, B. Th. Bjornsson, Y. Takagi
    Journal of Fish Biology 54 (3) 669 - 684 0022-1112 1999/03 [Refereed]
  • Yasuaki Takagi, Akiyoshi Takahashi
    The Anatomical Record 254 (3) 322 - 329 0003-276X 1999/03/01 [Refereed][Not invited]
  • SIGURDUR H. JOHANNSSON, PETRA PERSSON, YASUAKI TAKAGI, BJORN TH. BJORNSSON
    Annals of the New York Academy of Sciences 839 (1 TRENDS IN COM) 434 - 436 0077-8923 1998/05 [Refereed][Not invited]
  • Yasuaki Takagi, Björn Thrandur Björnsson
    General and Comparative Endocrinology 108 (1) 80 - 86 0016-6480 1997/10 [Refereed][Not invited]
  • Yasuaki Takagi
    The Anatomical Record 248 (4) 483 - 489 0003-276X 1997/08 [Refereed][Not invited]
  • PERSSON P.
    Journal of Comparative Pgysiology 167 (473) 468 - 473 1997 [Refereed][Not invited]
  • Y Takagi, B Th Björnsson
    Journal of Endocrinology 149 (2) 357 - 365 0022-0795 1996/05 [Refereed][Not invited]
     
    Abstract The actions of 3,3′,5-tri-iodo-l-thyronine (T3) and recombinant human IGF-I (rhIGF-I) as well as their interaction on cartilage growth in rainbow trout (Oncorhynchus mykiss) were examined. Uptake of 3H-methyl thymidine and 35S-sulfate by isolated branchial cartilage was measured as a marker for chondrocyte proliferation and sulfated glycosaminoglycan synthesis respectively. When T3 (1·0 μg/g) was injected intraperitoneally, plasma T3 levels reached a transient peak after 1 day and decreased rapidly thereafter. Sulfate and thymidine uptake were not affected by T3 at 1 and 3 days post-injection, but at 6 days post-injection both were significantly higher in T3injected fish than those in controls. The stimulatory effects of a T3 injection on sulfate and thymidine uptake were dose-dependent over the range of 0·01, 0·1 and 1·0 μg/g. In vitro exposure of cartilage to T3 (0·075, 0·75, 7·5, 75 and 750 nm) for 6 days resulted in dose-dependent stimulation of sulfate uptake, with a maximum response at 7·5 nm and higher. T3 exposure (7·5 nm) for 2 or 3 days also increased sulfate uptake, but only slightly. Thymidine uptake was not clearly affected by T3. In vitro addition of rhIGF-I (0·075, 0·75 and 7·5 nm) increased sulfate uptake, but not thymidine uptake, dose-dependently. Compared with T3, rhIGF-I induced a greater maximum level of sulfate uptake: at 7·5 nm rhIGF-I increased the uptake 17-fold whereas T3 increased the uptake fourfold. When T3 (0·075, 0·75 or 7·5 nm) and rhIGF-I (0·1 or 1·0 nm) were added together, stimulative actions of T3 on sulfate uptake were largely additive to those of rhIGF-I. The results indicate that T3 as well as IGF-I are important modulators of sulfated glycosaminoglycan synthesis in rainbow trout cartilage. Journal of Endocrinology (1996) 149, 357–365
  • Yasuaki Takagi, Toyoji Kaneko
    Cell and Tissue Research 280 (1) 153 - 158 0302-766X 1995/04 [Refereed][Not invited]
     
    Mineral-containing bone particles (BPs) were implanted intramuscularly into rainbow trout (Oncorhynchus mykiss) to investigate the sequence of appearance of bone-resorbing cells. A fibrous substance first surrounded the implanted BPs and was gradually replaced by connective tissue containing capillaries. Two weeks after BP implantation, relatively small multinucleated cells (type-1 cells), whose cytoplasm stained deeply with hematoxylin, appeared along the surfaces of the BPs. At later stages (after 4-8 weeks), the majority of cells which appeared to be resorbing the BPs were multinucleated cells whose cytoplasm stained deeply with eosin (type-2 cells). Type-2 cells contained more nuclei than type-1 cells. Electron-microscopical observations revealed that type-2 cells had the characteristic features of osteoclasts: the presence of numerous mitochondria, vacuoles and granules, and a differentiation of the cell membrane and cytoplasm into a ruffled border and clear zone, respectively. A tartrate-resistant acid phosphatase activity, which is an established characteristic of osteoclasts in terrestrial vertebrates, but which had not previously been examined in teleosts, was demonstrated histochemically in the type-2 cells. Development of type-2 cells was closely correlated with the development of connective tissue. These findings suggest that the development of a capillary network around the implanted BPs enables circulating osteoclast-progenitors to reach the surface of the BPs. © 1995 Springer-Verlag.
  • T. Kaneko, S. Hasegawa, Y. Takagi, M. Tagawa, T. Hirano
    Marine Biology 122 (1) 165 - 170 0025-3162 1995/03 [Refereed][Not invited]
  • Petra Persson, Yasuaki Takagi, Bjorn Thrandur Bjornssonl
    Fish Physiology and Biochemistry 14 329 - 339 1995 [Refereed][Not invited]
  • Yasuaki Takagi, Joe Hirano, Hiroshi Tanabe, Juro Yamada
    Journal of Experimental Zoology 268 (3) 229 - 238 0022-104X 1994/03/01 [Refereed][Not invited]
  • YAMANOME Takeshi, SHIDA Osamu, MITSUBOSHI Toru, TOKUSHIMA Masanori, OMURA Reiji, TAKAGI Yasuaki
    Aquaculture Science 日本水産増殖学会 42 (3) 389 - 396 0371-4217 1994 [Refereed][Not invited]
     
    Landlocked sockeye salmon (Oncorhynchus nerka) were transferred into seawater (SW) directly or after pre-acclimation to 50% seawater (50% SW) . The time course changes of their serum sodium level and weight increase were measured. Two similar experiments were conducted in November 1991 (0+year) and April 1992 (1+year), when osmoregulatory ability of the fish was low and high, respectively. In November 1991, serum sodium level of the fish pre-acclimated to 50% SW for 4 months was lower compared with that of directly transferred fish. Almost all of the directly transferred fish stopped growing in SW, whereas some of the pre-acclimated fish increased their weight. In April 1992, even in directly transferred fish, serum sodium level was lower compared with that of pre-acclimated fish in November. Pre-acclimation to 50% SW for 2 weeks did not enhance osmoregulatory ability further in spring. All individuals of both group increased their weight in SW. These data suggest that growth of landlocked sockeye salmon in SW may closely relate to the osmoregulatory ability of the fish at the time of transfer to SW.
  • Yasuaki Takagi, Juro Yamada
    Comparative Biochemistry and Physiology Part A: Physiology 105 (3) 459 - 462 0300-9629 1993/07 [Refereed][Not invited]
  • Yasuaki Takagi, Juro Yamada
    Comparative Biochemistry and Physiology Part A: Physiology 102 (3) 481 - 485 0300-9629 1992/07 [Refereed][Not invited]
  • Yasuaki Takagi, Shunsuke Moriyama, Tetsuya Hirano, Juro Yamada
    General and Comparative Endocrinology 86 (1) 90 - 95 0016-6480 1992/04 [Refereed][Not invited]
  • Takagi Yasuaki, Hirano Tetsuya, Yamada Juro
    Zoological Science 日本動物学会 6 (1) 83 - 89 0289-0003 1989 [Refereed]
  • Takagi Yasuaki, Hirano Tetsuya, Yamada Juro
    Comparative Biochemistry and Physiology Part A: Physiology 92 (4) 605 - 608 0300-9629 1989/01 [Refereed][Not invited]
  • Takagi, Y, Y. Nakamura, J. Yamada
    Zoological science Zoological Society of Japan 2 (4) 523 - 530 0289-0003 1985 [Refereed][Not invited]
     
    Effects of stanniectomy (CSX) on the absorption of Ca in the intestine of rainbow trout were examined by incubating the everted gut sac in Ringer solution. The serum Ca concentration increased by CSX in fish adapted to 1/3 SW but not in those adapted to FW. Ca moved from mucosa to serosa in the anterior intestine from FW-shams and the movement was not affected by CSX. The absorptive movement of Ca was not evident in 1/3 SW-shams but became apparent following CSX. Transports of water and other electrolytes (Na, Cl, K, Mg and Pi) showed no significant changes by CSX. The results indicated that the intestine is a target organ for an active principle of the CS, which are activated in a high-Ca environment to prevent Ca entry from the ambient water.

MISC

Books etc

  • ウナギの科学
    塚本勝巳 (Joint work第3章 3.2 骨格)
    朝倉書店 2019
  • 魚類学の百科事典
    (Joint work骨組織の形成と代謝)
    丸善出版 2018
  • 魚類学
    矢部 衞, 桑村 哲生, 都木 靖彰 (Editor)
    恒星社厚生閣 2017 377
  • マリンバイオテクノロジーの新潮流
    シーエムシー出版 2011

Association Memberships

  • （社）日本動物学会   日本水産学会   日本水産増殖学会   Zoological Society of Japan   

Research Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/04 -2025/03 
    Author : 都木 靖彰, 浦 和寛, 東藤 正浩
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/07 -2023/03 
    Author : 都木 靖彰, 浦 和寛
     
    小課題1．チョウザメ脊索Ⅱ型コラーゲン（NC）を用いたⅡ型コラーゲン線維コート技術の開発： 本研究室で開発されたチョウザメ浮袋コラーゲン（SBC）を用いた線維コート技術 (Moroi et al., DOI: 10.1016/j.msec.2019.109925) を基盤としてNCの線維コート技術を開発した（線維コートとは、コラーゲン原線維を培養容器底面に一様にコーティングする技術で、生体組織のコラーゲン性基質と細胞とのインタラクションの研究を可能にする新技術である）。Ⅱ型コラーゲン溶液の濃度、線維化バッファー（リン酸バッファー）の濃度、ｐH、インキュベーション温度などを最適化することで、世界で初めてⅡ型コラーゲンの線維コートに成功した。また、マウス軟骨前駆細胞ATDC5を用いた培養試験を実施し、Ⅱ型コラーゲン分子コートと比較して線維コート上では細胞増殖速度が低下する一方で軟骨基質産生を示すアルシアンブルー染色が強陽性となる（＝前軟骨細胞から成熟軟骨細胞への分化が促進される）ことを確認した。今後軟骨細胞遺伝子発現量を定量する。 小課題2．NCを用いた3次元足場ゲルの開発： 市販のブタⅠ型コラーゲンのゲル化法を参考に、細胞毒性の低い架橋剤ゲニピンを添加することで、NCを用いてNC原線維から成るゲルとNC分子からなるゲルの合成に成功した。今後ゲルの粘弾性や細胞培養への応用技術を開発する。 小課題3．SBCもしくはNCを用いた軟骨細胞spheroid作成技術の開発： SBCを用いてマウス由来前骨芽細胞MC3T3-E1をスフェロイド化する技術を応用し、ATDC5細胞のスフェロイド化に挑戦した。しかし、MC3T3-E1がスフェロイド化する条件ではATDC5細胞はスフェロイド化しなかった。本技術開発には別のアイディアが必要であると思われる。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
    Date (from‐to) : 2019/06 -2021/03 
    Author : Takagi Yasuaki
     
    The micron-order bundles are the morphology of collagen observed in animal bodies and give stiffness to the tissue. Thus, clarifying the bundle formation mechanism will support the development of cellular scaffolds that have the mechanical strength required for tissue engineering. Since mammalian collagens do not form such bundles in vitro, we use the sturgeon collagen, that can form bundles, and developed key technologies, such as high-speed AFM and digital microscopies, which enable us to directly observe the process of micron-order bundle formation in vitro. In addition, the technology to regulate the diameter of collagen fibrils and bundles by changing NaCl and phosphate buffer concentrations, coating collagen bundles or fine fibrils on cell-culture wells, and culturing the cells on the surface were developed. These technologies are powerful tools to further clarify the bundle formation mechanism and the effects of bundles on cellular functions in the future.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2018/04 -2021/03 
    Author : Takagi Yasuaki
     
    Aiming to percutaneously apply collagen peptides (CPs) as the acute and chronic wound-healing accelerator, new collagen-purification and gelatin-extraction technologies that show excellent yield and collagen content were developed. Then, the effects of subcritical water treatment on antioxidant activity and fibroblast-activating activity of enzymatically hydrolyzed CPs were examined. The subcritical-water treatment further hydrolyzed enzymatically hydrolyzed CPs into smaller peptides and increased CPs' antioxidant activity. However, it did not change fibroblast (L929) migration and proliferation activities of enzymatically hydrolyzed CPs. The more extended treatment inhibited fibroblast migration and decreased CPs' proliferation-promoting activity. These data strongly suggest that the appropriate treatment with subcritical water makes enzymatically hydrolyzed CPs higher antioxidant activity, which is suitable for acute and chronic wound-healing accelerators.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2017/04 -2020/03 
    Author : SAEKI HIROKI
     
    Modification of fish meat-derived digestive peptides conjugated with alginate oligosaccharide (AO) using the Maillard reaction significantly enhanced anti-inflammatory function. Isoelectric focusing without amphoteric electrolytes (Autofocusing) was an effective means for concentrating and separating only AO-bound anti-inflammatory peptides from the digested fish meat. The negative charge of carboxyl groups of uronic acids in AO was involved in the concentration of anti-inflammatory peptides. It was also clarified that this uronic acid would be an important factor for the enhancement of anti-inflammatory function. Furthermore, collagen peptide also enhanced anti-inflammatory function by AO-modification. These finding suggest the practical versatility of the AO-modification using the Maillard reaction as a manner for production of anti-inflammatory edible peptides.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Takagi Yasuaki, URA Kazuhiro, TODO Takashi
     
    We developed organ culture system using the sea urchin gonads for analysis of endocrine system during the gonadal growth. To date, it is well known that growth of gonad by synthesis and stored of MYP. The aim of this present study is identification of hormonal chemicals to induce the gonadal growth in sea urchin. We performed organ culture using the sea urchin gonads in the coelomic fluids of sea urchin, we measured MYP mRNA levels in the gonads by qPCR after incubation for 3days. The levels of MYP mRNA were no changing after incubation. It is suggested that MYP synthesis by nuclear receptor in gonads. Moreover, we extracted total lipids fraction form the gonads of sea urchin, and then gonads were incubated in the medium containing total lipids. However, NYP mRNA was no induced in this experiment. In the present study, we can’t identify the gonadal stimulation hormone in sea urchin. In future, we will try the comparison of colemic fluids compounds during gonadl growth.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2013/04 -2016/03 
    Author : Ura Kazuhiro, TAKAGI Yasuaki, IJIRI Shigeho
     
    It is still unclear that the endocrine system such as synthesize and/or embolism of steroid hormones during the period of gonadal growth in sea urchin. This study aimed to identify genes involved in gonadal growth and to investigate gene expression in the period of gonadal growth in sea urchin. RNA-seq analysis using next-generation sequencer was carried out on growing gonads of the Northern sea urchin, Mesocentrotus nudus. BLASTn analysis identified 22 transcripts potentially involved endocrine factors such as nuclear receptor (NR) and 21 transcripts of P450 in the growing gonad. However, the homologous genes as ER, AR, P450scc, P450c17, P450arom were not observed in sea urchin. In these analysis, it is suggested that sea urchin has no sex steroid hormones as same as vertebrate. These results suggested that sea urchin synthesized steroid hormones as same as other insects.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2012/04 -2016/03 
    Author : Adachi Shinji, ARAI Katsutoshi, TAKAGI Yasuaki, HIRAMATSU Naoshi, YAMAHA Etsuro, IJIRI Shigeho
     
    Identification of genes that express by stage specific manner and quantification of their mRNA levels in gonads were conducted throughout the periods of molecular sex differentiation, morphological sex differentiation, oocyte growth and maturation in Russian and Amur sturgeons using a next-generation sequencer. The information obtained from this study was utilized in the application for the development of techniques on sexing in the early developmental stage, induction of sexual maturation in the earlier gonadal developmental stage, production of good quality eggs and production of all female population.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2012/04 -2016/03 
    Author : Takagi Yasuaki
     
    I conducted comprehensive cDNA cloning of SLRPs in zebrafish and goldfish, and 10 new sequences were deposited to the database (DDBJ). Then, spatiotemporal expressions of mRNAs of decorin (dcn), biglycan (bgn), chondroadherin (chad), lumican (lum), osteoglycin (ogn) and dermatopontin (dpt) were clarified. In addition, recombinant proteins of Dcn, Bgn and Dpt and their specific antibodies were produced, and immunohistochemical localizations of these proteins were clarified. Hybrid gel made of recombinant Dpt and type I collagen was developed. Moreover, dpt-knock down experiment revealed that Dpt regulated m RNA expressions, fibril diameter and alignment of both type I and type II collagens in zebrafish. All these data are new to science, and the present results opened the possibility of new hybrid scaffolds consisted of collagen fibrils and SLRPs/Dpt.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011 -2013 
    Author : TAKAGI Yasuaki, URA Kazuhiro, TODO Takashi
     
    Sea urchin gonadal growth is characterized by intragonadal nutrient storage and the use of the stored nutrient for gametogenesis. Before gametogenesis initiation, gonads increase in size by accumulating nutrients such as proteins, lipids and carbohydrates in nutritive phagocytes that fill the gonadal lumina of both sexes. The major protein is termed major yolk glycoprotein or major yolk protein (MYP), which is a glycoprotein having molecular weight of 160-180 kDa, and has significant roles in gametogenesis. However, we have no information about gonadal development mechanisms, as well as the regulation mechanism on the synthesis of MYP in gonads. Therefore, to understand the mechanisms of gonadal development, we developed quantitative PCR system of MYP mRNA expression as well as an organ culture systems using sea urchin gonads. These techniques will enable a endocrinological research on gonadal developments in the sea urchin.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2010 -2012 
    Author : URA Kazuhiro, TAKAGI Yasuaki
     
    Subtilase and cellulase exhibited hydrolytic activity toward carboxymethyl cellulose with optimum temperature and pH at 30 °C and pH 8.0, respectively. The thermal stability was characterized and temperature at which activity decreased to50% by the 30 min treatment at pH 7.0 was 32 °C. The isolated cellulase activity was remained at high level at 5-20 °C which is growth temperature of the short-spined sea urchin. Thus, we confirmed that a cellulase of the short-spined sea urchin is adaptiveenzyme around low water temperature.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2009 -2012 
    Author : TAKAGI Yasuaki, IKOMA Toshiyuki, URA Kazuhiro
     
    Using MS analysis, scale SLRPs, which were possible regulators of 3-dimensinal architecture of teleost fish collagen, were identified. After the cDNA cloning of SLRPs, localization of their mRNAs were clarified. We also revealed a negative correlation between collagen denaturation temperature (DT) and contents of α3-subunit, as well as positive correlation between DT and hydroxylation ratio of proline residues in the collagen. Thus, these two factors seem to be the major regulators of DT of fish collagen. Artificial fibrillogenesis of collagen under magnetic field enabled a synthesis of a material having relatively aligned collagen fibrils, whose viscoelasticity and tensile strength were highest under 4 T and 12 T, respectively. High-density meso-porous new material was also synthesized using fish collagen.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Creative Scientific Research
    Date (from‐to) : 2005 -2009 
    Author : NAGASAWA Hiromichi, KOGURE Toshihiro, TAKAGI Yasuaki, SAKUDA Shohei
     
    It has been hypothesized that biomineralization, an action of mineral formation by organisms, is regulated by a small amount of organic materials included in biominerals. Using calcified tissues of some aquatic organisms we searched for calcification-regulating organic compounds, and purified them for structural and functional identification. We also clarified the crystallographic properties of each calcified tissue by electron microscopic analyses and verified the hypothesis by discovering many high- and low-molecular-weight organic compounds, which regulate calcification.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2006 -2008 
    Author : TAKAGI Yasuaki, URA Kazuhiro, IKOMA Toshiyuki
     
    ウロコのコラーゲンを用いて再生医療用人工基質の合成をめざして、生物学と材料科学の両面から研究を推進した。生物学的アプローチにより鱗形成細胞分化の分子機構、コラーゲン配向を制御する候補分子、組織ごとのコラーゲンα鎖組成を明らかにした。また、材料科学的アプローチにより、ブタ及びティラピアコラーゲン線維配向ゲルを高磁場内で実現するとともに、湿潤環境下による乾燥により10~20wt%の高密度化に成功した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    Date (from‐to) : 2006 -2007 
    Author : 都木 靖彰, 浦 和寛
     
    我が国の水産業において、水産無脊椎動物は重要な増養殖対象動物としての位置を占めており、種苗生産・放流や養殖が盛んに行われている種も多い。近年、日本沿岸域における水産生物資源、特に無脊椎動物の資源量は減少傾向にあることから、今後は優良品種の育種や高度で効率的な増養殖技術の開発が必要になると考えられるが、水産無脊椎動物においてそのような試みは著しく立ち遅れている。その大きな理由として、水産無脊椎動物の成長や成熟を制御する内分泌系に関する基礎的知見が極めて少ないといえる。比較的研究されているウニでも、糖質・脂質・タンパク質の代謝を制御する内的因子(ホルモンなど)の存在の有無や、それらの作用機序について正確に把握されていないのが現状である。本研究は、ウニをモデル生物として選定し、無脊椎動物の内分泌機構の解明に着手するものである。 今年度は、エゾバフンウニ消化器官において、モルモット抗ブタインスリン抗血清を用いて免疫組織化学的解析を行った。その結果、胃において消化管内腔側の上皮細胞の小さな顆粒に陽性反応が認められた。また、卵巣、精巣、放射神経にも免疫陽性反応が認められた。このことからエゾバフンウニにインスリン様物質が局在している可能性が示された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2004 -2005 
    Author : SHIMIZU Motohiro, TAKAGI Yasuaki, OJIMA Takao, URA Kazuhiro
     
    The sea urchin is an important coastal fisheries resource in Hokkaido. Unfortunately, they have been decrease in natural stocks, and therefore aquaculture techniques are required. In order to develop possible culture methods, physiological roles of digestive canal under artificial conditions should be revealed. However, there is little information on the fine structure and physiological roles of the digestive canal of the sea urchin. Following results were obtained. 1.The digestive canal of the sea urchin has following five parts, pharynx, esophagus, stomach, intestine and rectum. In the epithelium layer of the pharynx and esophagus, two types of granular cells stained with PAS and/or alcian blue were observed. Some granules observed in pharynx and esophagus were also stained with Hematoxylin. In epithelium layer of stomach, one type of granules were found. These granules were secreted in apical region of cytoplasm. 2.In order to obtain information about carnivorous actions of sea urchin, we investigated the occurrence of proteases in the sea urchin viscera and purified a major protease. N-terminal and internal amino acid sequences of the protease showed 37.9-55.2% identity to those of subtilisin-like alkaline serine protease, i.e. a subtilase. We determined the entire amino acid sequence of the protease using cDNAs amplified by PCR from cDNA library using degenerated primers. The mature sea urchin subtilase was considered to consist of 311 residues with calculated molecular mas of 32,270 Da. Primary structure of catalytic domain of the sea urchin subtilase showed 33-46% identity with those of bacterial subtilases such as subtilisin, proteinase K, and aqualysin. 3.In this study, we attempted to isolate and characterize a cellulose from sea urchin. A cDNA library from sea urchin digestive tracts was constructed and cDNA encoding SnEG54 were amplified by the PCR using degenerate primers designed from the partial amino acid sequences of SnEG54. By overlapping the amino acid sequence of 444 residues was deduced from the coding region. The amino acid sequence of mature SnEG54 showed 57, 55 and 51% identity with the corresponding regions of termite, sea squirt, and abalone cellulases, respectively.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    Date (from‐to) : 2004 -2005 
    Author : 都木 靖彰, 浦 和寛
     
    1.昨年にひきつづき、キンギョの鱗再生にともない発現するRunx2(Cbfa1)およびBMP2,4遺伝子の塩基配列決定をおこなった。Runx2は4種のアイソフォームの全塩基配列を決定した。BMP2はほぼ70%程度の配列の決定を終えた。キンギョRunx2遺伝子はこれまでに報告されたゼブラフィッシュRunx2bと最も高い相同性(約90%)を示した。BMP2および4のcDNA断片はゼブラフィッシュBMP2および4と高い相同性を示した。 2.鱗有機基質の主成分であるキンギョI型コラーゲンα鎖cDNA塩基配列を決定した。3種のα1(I)cDNA(α1(I)-A,B,C)を得、α1(I)-Aはその全塩基配列を、α1(I)-B,Cはその70%を決定した。α2(I)も3種のcDNAを得、それらの全塩基配列を決定した。α3(I)は1種類の全塩基配列を決定した。キンギョα鎖は、ゼブラフィッシュα鎖と約90%、哺乳類のα鎖と約70%の相同性を示した。また、分子系統樹ではα3(I)がα1(I)から分岐していることが確認された。さらに、既報の脊椎動物I型コラーゲンα鎖のPro残基数とコラーゲン変性温度の関係を近似式で表し、Y=0.3853X-44.712(r=0.9916)を得た。ここで、Y:変成温度(℃)、X:アミノ酸1000残基あたりのPro残基数である。この式を用いてキンギョのコラーゲンの変成温度を推定したところ、変成温度は三量体を構成するα鎖の組成で異なり、α3(I)鎖を多く含むと変成温度が高くなることが示された。 3.低リン・低カルシウム条件下におかれたキンギョの再生鱗の有機基質の微細構造解析をおこなった。リン酸カルシウム結晶は、非コラーゲン性有機基質の電子密度の高い物質中で形成され、成長することを明らかにした。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2003 -2005 
    Author : TAKAGI Yasuaki, ARAI Takaomi, ABE Syuiti, YAMAHA Etsuro
     
    For trace-elemental fingerprint studies in fish otoliths, industry-coupled plasma mass spectrography (ICPMS) has not used in Japan. The present study was undertaken to develop ICPMS-based trace-elemental fingerprint studies in the hard tissues of cultured fish and shellfish in Japan. Following results were obtained. 1. We developed standard methods to determine trace-elemental composition of fish otoliths and shells of shellfish using solution-based and laser abration ICPMS. Trace-elemental compositions were useful fingerprints that could identify product origin of cultured species. 2. We clarified migratory patterns of some salmonid and eel species using Sr contents and Sr/Ca ratio of otoliths determined by EPMA and revealed that the method is a powerful tool to study migration patterns of anadromous, catadromous or diadromous fishes. 3. We developed a DNA microarray to identify stocks of chum salmon. The array was accurate and time effective, and required no special equipments such as DNA sequencer. Therefore, the method is especially a powerful tool to identify chum salmon stocks in the field study and on board. 4. We immunohistochemically localized otolith matrix proteins, OMP-1 and otolin-1, and suggested important rolls of these proteins in calcification and formation of otolith micro structures. We also revealed that the aragonite saturation ratio of endolymph was maintained over 1.0 through the day-night cycle, suggesting aragonite crystal growth could be continued through a day. On the other hand, mRNA expression of otolin-1 showed clear daily rhythm with significantly higher expressions during night-time, suggesting a key fuction of otolin-1 to construct daily rings. In masu salmon, increases in Sr concentrations and Sr/Ca ratios in the serum occurred 7 days after the seawater transfer. Such a time-lag must be taken into account to reconstruct migration patterns in the anadromous fishes.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2001 -2004 
    Author : MIYAZAKI Nobuyuki, OTOBE Hirotaka, AMANO Masao, ARAI Takaomi, TANABE Shinsuke
     
    We investigate distribution, migration, growth, reproduction, feeding habit, population identification of dolphins and seals in the various areas of the world. And we also enforce monitoring study on marine pollution of organochlorine compounds (OCs), organotin cimpounds (BTs), heavy metals, and radionuclides, using samples of marine mammals. We published 93 scientific papers (88 in English and 4 in Japanese) with the peered referees, 23 articles (4 in English, 19 in Japanese) and one English proceedings. In the international and national academic conference, we made 77 presentations (38 in English and 39 in Japanese). Accumulation study of hazardous chemicals such as OCs, BTs and heavy metals survey provided the interesting scientific evidence of Dall's porpoises. Since 1991 when the former USSR was collapsed, Caspian Sea faced severe environmental condition. Main reason of the mass die-off of several thousands Caspian seals occurred in 1997, 1998 and 2000, might be due to the lowered immune system of the species. We found the A-type influenza virus (A/Bangkok/1/79/HsN2) in the serum samples of Caspian seals. This influenza virus has been active in the Caspian seals for more than 20 years. In the near future, humans might be infected with this virus all over the world. Thus, we need to establish the well-organized research system for this matter. We investigated evaluation of mitogen-induced responses in marine mammals and human lymphocytes by in-vitro exposure of BTs. Significant suppression was observed when the cells were exposed at normal level in the nature, suggesting BTs are strong toxic chemical. And we also found significant effect of plural hazardous chemicals. This study suggests that we need to establish the long-term monitoring system in marine ecosystem.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2001 -2002 
    Author : TAKAGI Yasuaki
     
    1. Identification of otolith-matrix-producing cells and localization of matrix proteins in the otolith : Specific antibodies against the major proteins of otolith matrix, OMP-1 and otolin-1, were raised and immunohistochemistry was conducted. The squamous epithelial cells and the transitional epithelial cells of the inner ear sacculus were identified as OMP-1-producing cells, whereas the cells located at the most periferal region of the sensory epithelium were identified as otolin-1-producing cells. The OMP-1 was contained in the otolith only, whereas the otolin-1 was included in both the otolith and the otolith membrane (gelatinous layer). The electron microscopy revealed that the otolith was composed of two types of the organic matrices, a dense sheet-like matrix and a fine meshwork matrix. Both OMP-1 and otolin-1 were detected in the meshwork. Differences in the density of the meshwork matrix makes daily rings, thus it is possible that the daily changes in the rate of production and/or deposition of OMP-1 and otolin-1 closely relate to the formation of the daily rings. 2. Development of real-time quantitative PCR system for OMP-1 and otolin-1 mRNA expression : We have developed the real-time PCR system to quantify OMP-1 and otolin-1 mRNA expression levels from the left and right sacculi of the individual rainbow trout. The daily changes of the expression levels of OMP-1 and otolin-1 mRNA were now under the investigation. 3. Determination of the supersaturation ratio of the inner ear endolymph : Otolith is composed of calcium carbonate poly crystals crystallized from the endolymph. Therefore, the growth rate of the otolith calcium carbonate must be highly dependent on the supersaturation ratio (S_a) of the endolymph. We have measured individually the ionic composition of the endolymph and calculated the S_a. The endolymph S_a was 2.027-4.303, clearly indicating that the endolymph is supersaturated with respect to the aragonite. The S_a was closely related to the pH of the endolymph, thus, pH-regulation of the endolymph is crucial for the otolith growth.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B).
    Date (from‐to) : 1999 -2000 
    Author : NAITO Yasuhiko, TAKAGI Yasuaki, UEDA Hiroshi, TANAKA Hideji, KATO Akiko, IIGO Masayuki
     
    We could obtain continuous data of swimming body axis, tail beat activity for two days from two coastal-migrating chum salmon in Otsuchi coast, Iwate in 1999 using micro-data loggers, which have never been successfully obtained in the past. Analysis of these data showed that salmon consumed more energy for ascent than descent and never control the air volume in the air bladder. We also succeeded to obtain 51days continuous data of swim speed, swim depth and ambient temperature from a offshore-migrating chum salmon in July, 2000. We attached a micro-data logger to a salmon at mid south of Bering Sea and recovered at coast of Nemuro city of Hokkaido. Preliminary analysis suggested that salmon swam at a mean speed of 36.2km/day. This means 2427km of swim distance in total during 51days, which occupied 80% of total 2760km of horizontal distance from release point to recaptured point. We also conducted data-logger experiment on 30 trout, Oncorhynchus nerka, at Chuzenji Lake in 1999 and 2000 and successfully obtained data of swim depth and ambient temperature from 23 fish. From experiments we expected behavioral and temperature-physiological difference in their performance between condition of gonads of both sex. Data are under analysis.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1999 -2000 
    Author : 都木 靖彰
     
    耳石に刻まれる日周輪やチェックリング読みとりの正確性を増し、さらなる情報を解読するためには、内耳内リンパ液の微量採取法、イオン組成測定法、耳石有機基質産生活性測定法を確立し、それらが日周輪・チェックリング形成に果す役割を解明することが必要である。 昨年度に確立した方法を用いて、ニジマスの内リンパ液のイオン組成と炭酸カルシウムアラゴナイトに対する過飽和度を求め、内リンパ液の過飽和度とpH、二酸化炭素分圧、炭酸イオン濃度、Caイオン濃度との関係を解析した。その結果、過飽和度は内リンパ液のpHに比例していることを明らかにした。このことは、内リンパ液のpHの調節により耳石成長量が調節されていることを示す。現在この成果について学術論文を執筆中である。 次に、ストレスとチェックリング形成との関係を明らかにする目的で、追い回しストレスが内リンパ液イオン組成に与える影響を調べた。短時間の追い回しストレスは血液の酸性化を引き起こしたが、内リンパ液のイオン組成、過飽和度には大きな変化がなかった。このことから、短時間のストレスはチェックリング形成の原因とならないものと結論できた。現在、繰り返しストレス、長時間のストレスの影響を調べている。 OMP-1は、我々のグループが世界に先駆けてその構造を明らかにした、耳石の可溶性有機基質であり、その成果を学術雑誌に論文として発表した(裏面参照)。また、現在OMP-1遺伝子発現量を競合PCR法を用いて調べている。 さらに、耳石有機基質の性質とその産生機構を明らかにする目的で、OMP-1の電顕的分布を調べるとともに、耳石に含まれる糖成分の解析を行った。これらの成果も学術雑誌に論文として発表した(裏面参照)。 以上の成果をまとめる目的で、耳石形成機構に関する二つの総説を学術雑誌に発表した(裏面参照)。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1997 -2000 
    Author : MIYAZAKI Nobuyuki, AMANO Masao, OTOBE Hirotaka, TAKAGI Yasuaki, TANABE Shinsuke
     
    We investigated taxonomy, reproduction, growth, behavior, feeding habitat of marine mammals, and environmental condition of their habitats polluted by hazardous chemicals (organochlorine compounds, organtin conpounds, and heavy metals, etc). Concerning this project, we published 37 scientific papers, and 36 articles of book and report. We also made 49 presentations in the international and domestic scientific society, and also 28 lectures to public people. Based on these scientific results, we recommended actual management of marine mammals, which involved not only information on life history parameters but also information on marine pollution. We disseminated these scientific information to the public people in the worlds by home page (http : //wakame.ori.u-tokyo.ac.jp).
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1997 -1998 
    Author : 都木 靖彰
     
    硬骨魚類の耳石は、年齢、日齢査定形質として水産学研究に必要不可欠な硬組織である。にもかかわらず、年輪・日周輪形成メカニズムはいまだに解明されていない。本研究は,耳石日周輪形成メカニズムを、主に耳石有機基質の産生メカニズムから解明しようとするものである。本年度は昨年度に引き続き、以下の諸点を明らかにした。 1. 抗耳石可溶性基質抗体を用いた透過型電顕組織化学を昨年に引き続き行い、移行上皮細胞・扁平上皮細胞における耳石可溶性基質産生機構およびその耳石への取り込み機構を明らかにした。可溶性基質は産生後、移行上皮細胞では小型の、扁平上皮細胞ではより大型の分泌小胞中に保存された後、エクソサイトーシスにより内リンパ液中へと分泌される。分泌された可溶性基質が内リンパ液中から耳石へと取り込まれていく様子も観察された。 2. 小嚢上皮・耳石のレクチン組織化学法および、耳石可溶性基質・内リンパ液のドットプロット法により、小麦胚芽、コンカナバリンAおよびインゲンマメレクチンに反応するN一結合型糖鎖を含む物質が感覚細胞および支持細胞から耳石膜を介して、あるいは移行上皮細胞および支持細胞から内リンパ液を介して耳石に取り込まれることを明らかにした。 3. ニジマス耳石割断面を走査型電子顕微鏡で詳細に観察したところ、小石状、平板状、球状など様々な結晶構造が観察された。現在、これらの構造がすべてあらゴアナイトからできているのか、他の結晶系(カルサイトなど)が混在しているのか、X線回折を行うべくサンプルを準備中である。それと平行して耳石可溶性基質抗体を用いた免疫組織化学を走査型電顕上で行うべく技術開発中である。 以上の結果は、タンパク質に加えて糖質、たぶん糖タンパク質が耳石形成に重要な機能を果たしていることを示唆する。今後耳石基質タンパク質や糖鎖の構造を明らかにし、その機能を解明する必要がある。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1996 -1996 
    Author : 都木 靖彰
     
    耳石は耳石特有の有機基質に炭酸カルシウムが沈着して生長するとされる。本研究は、糖と特異的に結合するレクチンを用いて耳石有機基質の糖構造の決定、その産生細胞の特定および産生機構の解明を目的として行われた。材料としてニジマスの最も大きい耳石(扁平石)を包む内耳膜迷路である小嚢を用いた。研究結果の概要は以下の通りである。 1.透過型電子顕微鏡観察により、小嚢上皮細胞を感覚細胞、支持細胞、移行上皮細胞、Mitochondria-rich cell(MRC)、扁平上皮細胞に分類した。MRCを除くすべての細胞が分泌活性を有するタンパク合成細胞であり、耳石形成に関与することを示唆した。 2.MRCは、その微細構造はイオン輸送生細胞の特徴を有し、代表的なイオンポンプであるNa^+,K^+-ATPaseを高濃度に持つことを証明した。このことから、MRCは小嚢内リンパ液の特殊なイオン組成の形成にあずかるイオン輸送性細胞であると断定した。 3.アルシアンブルー。PAS染色により、耳石には主として産生多糖類が、耳石膜には酸性多糖と中性多糖両方が含まれることを明らかとした。小嚢上皮のレクチン組織化学染色により、感覚上皮・移行上皮・扁平上皮細胞にはマンノース・N-アセチルグルコサミンが、支持細胞にはマンノースが含まれることを証明した。一方、ガラクトースやN-アセチルガラクトサミンが小嚢上皮に含まれる可能性は低いことを解明した。耳石抽出物を電気泳動・ウェスタンブロッティング後、レクチン(ConA)染色したところ、耳石基質タンパクの主要な成分はマンノースを含む糖タンパクであった。同様の成分は内リンパ液中にも存在した。これらのことから、小嚢上皮に含まれるマンノースの少なくとも一部は耳石基質タンパクと結合した後内リンパ液中に分泌され、耳石中に取り込まれることを示唆した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1994 -1996 
    Author : MIYAZAKI Nobuyuki, TANABE Shinsuke, AMANO Masao, TAKAGI Yasuaki, TAKEUCHI Ichiro, OTOBE Hirotaka
     
    We examined hazardous chemicals deposited in marine animals collected from the tropical waters to the Antarctic and the Arctic ocean. Research results have been published by 10 scientific papers, 6 books and 14 documentations, and reported by 13 oral presentations in scientific meetings. These scientific contents are summarized by the following 5 items ; (1) concentration of organochlorine compounds (PCB,DDT,BHC etc.) in dolphins collected from the worldwide areas and their biological impact, (2) concentration of organochlorine compounds (PCB,DDT,BHC etc.) in Baikal seals and their biological impact, (3) concentration of organotin compounds in dolphins collected from Japanese waters and their biological impact, (4) concentration of heavy metals (Hg, Cd, Pb etc.) in Aderie penguins collected from the Antarctic Ocean, and (5) future plan of international research organization on marine pollution.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (Research Fellowship)
    Date (from‐to) : 1989 -1990 
    Author : 都木 靖彰

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  • 特許6132299:コラーゲンを含む組成物    2017
    田中順三, 生駒俊之, 吉岡朋彦, 許哲峰, 都木靖彰, 浦和寛
  • 特開2016-187337:ウニ用畜養飼料  2016
    浦和寛, 都木靖彰, 今村聖祐, 村上雅之, 堤尚信
  • 特許第5043215号(P5043215):チョウザメ類脊索から簡便な抽出方法で得られるＩＩ型コラーゲン    2012/10/10
    都木靖彰, 浦和寛  国立大学法人北海道大学

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