研究者データベース

研究者情報

マスター

アカウント(マスター)

  • 氏名

    若松 純一(ワカマツ ジユンイチ), ワカマツ ジユンイチ

所属(マスター)

  • 農学研究院 基盤研究部門 畜産科学分野

所属(マスター)

  • 農学研究院 基盤研究部門 畜産科学分野

独自項目

syllabus

  • 2021, 食品安全・機能性開発学特論, Advanced Safety and Function of Food, 修士課程, 農学院, 食品安全性、予測微生物、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 食品安全・機能性開発学特論演習, Advanced Seminar on Safety and Function of Food, 修士課程, 農学院, 食品の安全、予測微生物学、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 大学院共通授業科目(一般科目):自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, 食品安全性、予測微生物、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 畜産食品衛生学, Milk and Meat Hygiene, 学士課程, 農学部, 畜産食品、乳、肉、食品衛生、食中毒
  • 2021, 畜産科学概論, Introduction of Animal Science, 学士課程, 農学部, 畜産科学、細胞組織生物学、応用食品科学、遺伝繁殖学、動物機能学、畜牧体系学
  • 2021, 応用食品科学, Applied Food Science, 学士課程, 農学部, 畜産食品、食用微生物
  • 2021, 畜産資源開発学, Animal Product Science, 学士課程, 農学部, 畜産物利用、機能性食品
  • 2021, 一般教育演習(フレッシュマンセミナー), Freshman Seminar, 学士課程, 全学教育, 生態系、家畜、畜産物、衣食住、文化
  • 2021, 畜産物品質管理学実験, Laboratory Exercise in Quality Control of Animal Products, 学士課程, 農学部, 品質管理、食品衛生、畜産食品、食品化学、食の安全
  • 2021, 基礎畜産物利用学Ⅱ, Fundamental Science of Animal Products II, 学士課程, 農学部, 食肉、骨格筋、と畜、死後変化、食肉製品、畜産副産物、皮革、細胞外マリックス
  • 2021, 酪農生産物利用学, Dairy Food Science and Technology, 学士課程, 農学部, 食肉、骨格筋、と畜、死後変化、食肉製品、畜産副産物、皮革、細胞外マリックス
  • 2021, 食肉科学, Meat Science, 学士課程, 農学部, 食肉、骨格筋、と畜、死後変化、食肉製品、畜産副産物、皮革、細胞外マリックス
  • 2021, 畜産物利用学実習, Practice on Animal Products Utilization, 学士課程, 農学部, 畜産物、食肉、食肉製品、乳、食品科学、皮革、鞣製

researchmap

プロフィール情報

学位

  • 博士(農学)(2002年12月 北海道大学)

プロフィール情報

  • 若松, ワカマツ
  • 純一, ジュンイチ
  • ID各種

    200901099352812530

対象リソース

業績リスト

研究キーワード

  • 食事誘発性体熱産生   パルマハム   亜鉛プロトポルフィリンIX   食肉製品   プロトポルフィリンIX   亜鉛   色   ヘム   筋原線維   タンパク質   食肉   ペプチド   筋原線維タンパク質   機能性物質   食肉タンパク質   食肉利用学   食肉生化学   

研究分野

  • ライフサイエンス / 動物生産科学
  • ライフサイエンス / 食品科学
  • 人文・社会 / 家政学、生活科学

経歴

  • 2024年04月 - 現在 北海道大学 大学院農学研究院 応用生命科学部門 教授
  • 2021年04月 - 2024年03月 北海道大学 大学院農学研究院 応用生命科学部門 准教授
  • 2013年01月 - 2021年03月 北海道大学 北方生物圏フィールド科学センター 准教授
  • 2012年07月 - 2012年12月 北海道大学大学院農学研究院 准教授
  • 2007年04月 - 2012年06月 北海道大学大学院農学研究院 助教
  • 2002年05月 - 2007年03月 北海道大学大学院農学研究科 助手
  • 1994年04月 - 2002年05月 伊藤ハム株式会社中央研究所 研究員

学歴

  • 1992年04月 - 1994年03月   北海道大学大学院   農学研究科   畜産学専攻
  • 1986年04月 - 1992年03月   北海道大学   農学部   畜産学科

委員歴

  • 2023年04月 - 現在   北海道環境生活部   エゾシカ肉品質管理のための検討懇話会
  • 2023年04月 - 現在   北海道畜産草地学会   会計幹事
  • 2015年04月 - 現在   日本食肉科学会   広報委員
  • 2015年04月 - 現在   日本食肉科学会   常務理事
  • 2015年 - 現在   日本畜産学会   機関紙編集委員
  • 2017年10月 - 2019年03月   北海道環境生活部   エゾシカわな捕獲技術等検討会委員
  • 2015年04月 - 2019年03月   日本食肉科学会   評議員
  • 2014年04月 - 2015年03月   北海道畜産草地学会   監事
  • 1998年04月 - 2015年03月   日本食肉研究会   編集幹事   日本食肉研究会
  • 2012年12月 - 2014年03月   北海道畜産草地学会   会計幹事
  • 2010年04月 - 2012年12月   北海道畜産学会   会計幹事   北海道畜産学会
  • 2007年04月 - 2009年03月   日本食肉研究会   庶務幹事   日本食肉研究会

受賞

  • 2016年06月 公益財団法人伊藤記念財団 第1回伊藤記念財団賞
     
    受賞者: 若松 純一
  • 2008年 畜産技術協会賞

論文

  • Napaporn Chintagavongse, Haruto Kumura, Toru Hayakawa, Jun-Ichi Wakamatsu, Koichi Tamano
    Journal of bioscience and bioengineering 2024年03月01日 [査読有り]
     
    The adjunct product with enzymatic activity from Aspergillus oryzae is beneficial for flavor enrichment in the ripened cheese. However, an excessive lipolytic reaction leads to the release of volatile free fatty acids. Accordingly, a strong off-flavor (i.e., rancidity) has been detected when A. oryzae AHU 7139 is used. To identify the rancidity-related lipase from this strain, we evaluated the substrate specificity and lipase distribution using five mutants cultured on a whey-based solid medium under different initial pH conditions. The results showed a higher diacylglycerol lipase activity than triacylglycerol lipase activity. Moreover, an initial pH of 6.5 for the culture resulted in higher lipolytic activity than a pH of 4.0, and most of the activity was found in the extracellular fraction. Based on the gene expression analysis by real-time polymerase chain reaction and location and substrate specificity, five genes (No. 1, No. 19, mdlB, tglA, and cutL) were selected among 25 annotated lipase genes to identify the respective knockout strains. Because ΔtglA and ΔmdlB showed an outstanding involvement in the release of free fatty acids, these strains were applied to in vitro cheese curd experiments. In conclusion, we posit that triacylglycerol lipase (TglA) plays a key role as the trigger of rancidity and the resulting diglycerides have to be exposed to diacylglycerol lipase (MdlB) to stimulate rancidity in cheese made with A. oryzae AHU 7139. This finding could help screen suitable A.oryzae strains as cheese adjuncts to prevent the generation of the rancid-off flavor.
  • Mar Llauger, Luis Guerrero, Jacint Arnau, Afra Morera, Jun-ichi Wakamatsu, Jose Manuel Lorenzo Rodriguez, RICARD BOU
    Foods 13 4 533  2024年02月09日 [査読有り][通常論文]
  • Haruka Abe, Yang Zhai, Yu Toba, Hiroki Masumo, Toru Hayakawa, Haruto Kumura, Jun-Ichi Wakamatsu
    Food chemistry 441 138317 - 138317 2024年01月02日 [査読有り][通常論文]
     
    The bright red color of Parma ham is mainly derived from zinc protoporphyrin IX (ZnPP), which exists in both water-soluble and insoluble states. Water-soluble ZnPP mainly binds to hemoglobin, however, the presence of water-insoluble ZnPP remains unexplained. Therefore, we aimed to elucidate how ZnPP exists in a water-insoluble state by focusing on its binding substance. Depending on the skeletal muscle, water-insoluble ZnPP comprised 30-50% of total ZnPP. The ZnPP water extractability was positively correlated with muscle pH. Water-insoluble ZnPP was extractable with a high-pH solution and existed as a complex with myoglobin or hemoglobin; nevertheless, myoglobin-binding ZnPP was more abundant. Furthermore, the water solubility of the myoglobin globin moiety at pH 5.5-6.0 was reduced by ZnPP binding. These results suggest that water-insoluble ZnPP mainly exists as a ZnPP-Mb complex, with low solubility attributed to the low pH of the ham.
  • Yang Zhai, Haruka Abe, Hung-Cheng Wang, Toru Hayakawa, Haruto Kumura, Jun-Ichi Wakamatsu
    Food chemistry 427 136755 - 136755 2023年11月30日 [査読有り]
     
    Zinc protoporphyrin IX (ZnPP) is the dominant red pigment in nitrate/nitrite-free dry-cured meat products such as Parma ham, and it is considered to be a potential alternative to nitrite/nitrate for reddening dry-cured meat products. Ferroheme and ferriheme dissociated from heme proteins in meat were proposed as substrates to form ZnPP. To elucidate their specific formation mechanism, nitric oxide, carbon monoxide, and azide were used to stable heme in heme proteins. The exogenous hemoglobin derivatives bound with these ligands showed lower heme dissociation compared with exogenous oxyhemoglobin and did not contribute to ZnPP formation. Meanwhile, azide inhibited almost all ZnPP formation by binding to ferriheme, indicating ferriheme dissociation from oxidized heme proteins, predominantly for ZnPP formation. Free ferriheme could not be converted to ZnPP unless it was reduced to ferroheme. Overall, ferriheme dissociated from oxidized heme proteins was the dominant substrate for conversion to ZnPP after re-reduction to ferroheme.
  • 銃捕獲した野生エゾシカの肉質に及ぼす被弾部位と口径の影響
    桒子和洋, 近藤誠司, 木富正裕, 亀井利活, 稲富佳洋, 河合正人, 日置昭二, 鳥羽悠, 早川徹, 玖村朗人, 若松純一
    食肉の科学 64 1 29 - 38 2023年06月 [査読有り]
  • Qingyun Huang, Nodoka Miyaki, Zongfei Li, Yutaroh Takahashi, Satoshi Ishizuka, Toru Hayakawa, Jun-Ichi Wakamatsu, Haruto Kumura
    Journal of the science of food and agriculture 103 8 4234 - 4241 2023年06月 [査読有り]
     
    BACKGROUND: Monascus sp. has been used in fermented foods for centuries. It can synthesize yellow, red, and orange pigments as secondary metabolites. Here, we focused on yellow pigment monascin, responsible for anti-inflammation and antidiabetic effects, and investigated whether whey could be a suitable substrate with or without rice powder for monascin production using M. purpureus AHU 9085, M. pilosus NBRC 4520 and M. ruber NBRC 32318. RESULTS: The growth and monascin production of the three Monascus strains were dependent on three liquid media consisting of whey and/or rice. All strains showed the best growth in a rice and whey mixed medium, in which M. ruber NBRC 32318 exhibited the highest total monascin production. Subsequent investigation of the effects of whey components indicated that a mineral cocktail in whey was particularly effective in stimulating the monascin production efficiency of M. ruber NBRC 32318. However, this recipe exhibited less stimulation, or even inhibition, for M. pilosus NBRC 4520 and M. purpureus AHU 9085, respectively. In terms of total monascin production, rice with whey provided the highest amount due to growth promotion along with relatively high production efficiency. CONCLUSION: The effect of whey on growth and monascin production was strongly dependent on the Monascus strains. Even a mineral cocktail in whey could regulate monascin productivity in a strain-specific manner. Further studies are needed to elucidate the mechanism behind the diverse responses by the minerals in the production of monascin from Monascus. © 2023 Society of Chemical Industry.
  • Toru Hayakawa, Yu Kubono, Shuji Fujii, Jun-Ichi Wakamatsu, Haruto Kumura
    Animal science journal = Nihon chikusan Gakkaiho 94 1 e13825  2023年 [査読有り]
     
    The heat-induced gelation of actomyosin plays a key role in meat processing. Our previous study showed that L-histidine could affect the characteristics of a heat-induced gel of myosin on a low ionic strength. To apply the specific effect of L-histidine to meat processing, the heat-induced gel properties of actomyosin in the presence of L-histidine were investigated. Actomyosin in a low ionic strength solution containing L-histidine did not form a gel upon heating. The dynamic rheological properties of actomyosin in low ionic strength solutions were distinct depending on the presence or absence of L-histidine. Electron microscopy showed that, heated at 50°C, actomyosin in a low ionic strength solution containing L-histidine remained a filamentous structure. The surface hydrophobicity of actomyosin was stable up to 50°C in a low ionic strength solution containing L-histidine. In conclusion, L-histidine might suppress the aggregation of actomyosin and inhibit heat-induced gelation in a low ionic strength solution.
  • Yang Zhai, Hung-Cheng Wang, Toru Hayakawa, Haruto Kumura, Jun-Ichi Wakamatsu
    Food chemistry 395 133604 - 133604 2022年11月30日 
    Most of the water-soluble zinc protoporphyrin IX (ZnPP) in Parma ham mainly exists as complexes with hemoglobin and myoglobin (ZnPP-Hb and ZnPP-Mb). To elucidate the formation mechanism of these complexes, a new experimental model to produce higher amount of water-soluble ZnPP complexes was established. ZnPP-Hb was detected as the main water-soluble ZnPP complex in this model, which is the same as that in Parma ham. Adding exogenous Hb into this model promoted higher ZnPP formation than with Mb added, indicating that Hb was the superior substrate for generating ZnPP compared to Mb. The increase in non-heme iron content with ZnPP formation in both the Hb- and Mb-added groups indicated that the release of iron ion from heme was a crucial step in ZnPP formation. ZnPP-Hb was formed when ZnPP non-enzymatically bound with apo-Hb. These results revealed the mechanism of why ZnPP-Hb is more dominant in Parma ham than to ZnPP-Mb.
  • Jun-Ichi Wakamatsu
    Meat science 192 108905 - 108905 2022年10月 [査読有り][招待有り]
     
    A large amount of zinc protoporphyrin IX (ZnPP) is found in nitrite/nitrate-free dry-cured meat products, such as Parma ham, and is known to contribute to the favorable bright red color of the latter. ZnPP is a metalloporphyrin, in which zinc is coordinated, instead of iron, in the porphyrin ring. ZnPP proved to be more stable than heme, and its formation should be favored in dried meat products to improve color without the addition of nitrites or nitrates. Toward that, understanding the mechanisms of formation of ZnPP in nitrite/nitrate-free dry-cured ham would be important. In this lecture, I introduce some of our research group's findings regarding the endogenous and exogenous factors contributing to the formation and distribution of ZnPP in Parma ham and why ZnPP formation is suppressed in common cured meat products.
  • Napaporn Chintagavongse, Hayate Takiguchi, Chi Ming-Hsuan, Koichi Tamano, Toru Hayakawa, Jun-Ichi Wakamatsu, Tomohiro Mitani, Haruto Kumura
    Journal of the science of food and agriculture 2022年01月23日 [査読有り]
     
    BACKGROUND: Aspergillus sp. has been used in traditional Japanese fermented foods. Protease-containing culture products of A. oryzae have been applied as the adjunct enzyme source to enrich the flavor in ripened cheese. Although proteolysis was stimulated, the increase of free fatty acids (FFA) was recognized in some products. Since an excess amount of FFA accumulation can cause rancidity in cheese products, the assessment of lipase activity was considered to be essential for the cheese adjunct preparation. RESULTS: Although an equal lipase activity from the adjunct materials of A. kawachii NBRC 4308, A. luchuensis RIB 2604 and A. oryzae AHU 7139 was applied to semi-hard cheese, the FFA level was significantly higher in A. oryzae cheese than in the others. Furthermore, the profiles of volatile components were different in experimental cheeses. An in vitro study with experimental curds demonstrated that the high FFA might not depend on the lipase retainability on curds. On the contrary, the pronounced activation of the lipases occurred in A. oryzae after incubation with the curds. Moreover, incubation of the insoluble lipase that had been attached to the cells with skim milk curd extracts allowed the release of lipases from the cells into the medium with remarkable activation. CONCLUSION: A. oryzae AHU 7139 possessed a complex lipolytic system comprising extracellular and cell-binding lipases that were attributed to the increase in FFA in A. oryzae cheese. © 2022 Society of Chemical Industry.
  • Hung-Cheng Wang, Toru Hayakawa, Haruto Kumura, Jun-ichi Wakamatsu
    Food Bioscience 40 100870 - 100870 2021年04月 [査読有り]
  • Md Kauser-Ul-Alam, Toru Hayakawa, Haruto Kumura, Jun-Ichi Wakamatsu
    Meat science 176 108467 - 108467 2021年02月19日 [査読有り]
     
    Zinc protoporphyrin IX (ZnPP)-forming food-grade lactic acid bacteria (LAB) were screened from various sources for their ability to improve the color of meat products. The effects of salt and nitrite on the ZnPP-forming ability of these bacteria were also investigated. Finally, these bacteria were applied in salt-added minced meat to assess their ability to improve the color. Twenty-five LAB were screened for their ZnPP-forming ability in pork. Most of the strains exhibited maximum growth anaerobically in 3% salt at 30 °C and grew well at pH 5.5 and 6.5. Moreover, 3% salt slightly retarded ZnPP formation; however, nitrite completely inhibited ZnPP formation in all the ZnPP-forming LAB. Thirteen LAB (avoiding duplication and non-food-grade) could form ZnPP in salt-added minced meat, resulting in improvement of the bright red color, high ZnPP autofluorescence, and increased fluorescence intensity. Finally, considering the safety, Lactobacillus plantarum, Lactococcus lactis subsp. cremoris, and Leuconostoc lactis were suggested as promising candidates to improve the color of meat products.
  • Md Kauser-Ul-Alam, Yu Toba, Shoji Hioki, Toru Hayakawa, Haruto Kumura, Jun-Ichi Wakamatsu
    Foods (Basel, Switzerland) 9 11 2020年10月31日 [査読有り]
     
    This study assessed the color improvement via zinc protoporphyrin IX (ZnPP) formation in nitrite-free, dry-cured sausages processed using five varieties of ZnPP-forming lactic acid bacteria (LAB). The ZnPP contents and color intensity of the sausages and other technological properties were analyzed during the processing of sausages. LAB count and acidity significantly increased in the LAB-inoculated sausages compared to the control group. The bright red color was observed both inside and outside the sausages inoculated with Lactococcus lactis subsp. cremoris and Leuconostoc lactis. However, a brown color was observed on the surface of the sausage inoculated with Lactobacillus spp. The redness of Lactococcus lactis subsp. cremoris-inoculated sausages was close to that of the nitrite-added group. Moreover, the external bright red color was improved by Lactococcus lactis subsp. cremoris due to the aerobic formation of ZnPP. Therefore, Lactococcus lactis subsp. cremoris can be used to improve the color of fermented meat products.
  • Md Asaduzzaman, Momo Ohya, Haruto Kumura, Toru Hayakawa, Jun-Ichi Wakamatsu
    Meat science 165 108109 - 108109 2020年07月 [査読有り]
     
    In order to improve the color of meat products by producing zinc protoporphyrin IX (ZnPP) in meat, we searched for edible bacteria with high ZnPP-forming ability. Eleven bacteria used in different animal products and 126 bacteria isolated from environmental and probiotic sources were assessed for their ability to form ZnPP. Many bacteria from both sources showed a high ZnPP-forming ability. Only three edible bacteria were identified from the 44 high ZnPP-forming isolates with 16S rRNA gene sequencing. High ZnPP-forming bacteria from both sources were inoculated in aseptic salt-added minced meat, and their ZnPP-forming abilities were evaluated. Lactococcus lactis, Leuconostoc mesenteroides, and Enterococcus faecium from environmental isolates produced a brighter red color, higher ZnPP autofluorescence and fluorescence intensity in salt-added minced meat than control. Furthermore, after heating, the color and ZnPP autofluorescence of the inoculated minced meat persisted to a degree. Therefore, it is possible to improve the color of meat products without nitrite/nitrate by using these promising ZnPP-forming edible bacteria.
  • Chintagavongse N, Yoneda T, Ming-Hsuan C, Hayakawa T, Wakamatsu JI, Tamano K, Kumura H
    Journal of the Science of Food and Agriculture 100 13 4834 - 4839 2020年06月 [査読有り][通常論文]
     
    BACKGROUND: Some species belonging to the genus Aspergillus have been used in traditional Japanese fermentation foods. A. sojae is the species responsible for high proteolytic activity. Freeze-drying treatments followed by physical disruption enables the pulverisation of mycelia of A. sojae RIB 1045 grown in whey protein base solid media. Through this protocol, intracellular proteases were extracted to compare extracellular protease activity in terms of the reaction pH dependence in the presence or absence of the inhibitors. RESULT: With different sensitivities to inhibitors, intracellular and extracellular proteases showed the highest activity under the acidic region, which was considered suitable for cheese application. The raw culture product (CP) and its freeze-dried product (FDP) were mixed with cheese curds prepared according to Gouda-type cheese making and were allowed to ripen for three months. Chemical analysis of the products showed 13.3% water-soluble nitrogen (WSN) in the control, which had received noncultured media, whereas 20.0% and 21.1% WSN were found in CP and FDP experimental cheese, respectively. Although these adjuncts significantly increased WSN, an insignificant difference was found between CP and FDP. Free fatty acids in all experimental cheeses were similar, showing that CP and FDP caused no rancid defects. CONCLUSION: An introduction of freeze-drying treatments accompanied by cell disruption resulted in a negligible effect in terms of WSN. However, the application of A. sojae can be beneficial when it comes to increasing the degree of WSN compared with A. oryzae, as shown in our previous study. This article is protected by copyright. All rights reserved.
  • 王鴻誠, 大屋桃, 早川徹, 玖村朗人, 若松純一
    日本畜産学会報 91 4 389 - 394 2020年 [査読有り]
  • Wakamatsu JI, Kawazoe H, Ohya M, Hayakawa T, Kumura H
    Meat science 161 107989 - 107989 2019年10月 [査読有り][通常論文]
     
    Zinc protoporphyrin IX (ZnPP) mainly contributes to the red color of dry cured ham without nitrites/nitrates. Here, we examined the effects of acids used for pH adjustment, pH, and microorganisms on ZnPP formation. The results showed that ZnPP formation and optimal pH were dependent upon the acid type. In the presence of microorganisms, the optimal pH for ZnPP formation shifted to higher values, with the amount of formed ZnPP markedly increased at the shifted optimal pH. Additionally, two bacterial strains isolated from incubated pork homogenate exhibited an enhanced ability to form ZnPP. Although the two isolated bacteria are not edible, inoculation with one bacterium into minced meat resulted in formation of large amounts of ZnPP and color closer to that of nitrite-added meat. These results suggest that appropriate food-grade bacterial strains can improve the color of various fermented meat products in the absence of nitrites/nitrates.
  • Kumura Haruto, Satoh Megumi, Machiya Taiki, Hosono Makoto, Hayakawa Toru, Wakamatsu Jun-Ichi
    INTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY 72 3 403 - 408 2019年08月 [査読有り][通常論文]
     
    The lipolytic and proteolytic activity of Penicillium camemberti PC TT033 and Penicillium roqueforti PR G3, cultured on the whey solids or simulated cheese media, were compared under several pH reaction conditions. Lipolytic activity was higher when both strains had been cultured on the whey medium than on the simulated cheese medium, whereas proteolytic activity was less influenced by the culture medium. The relationship between the reaction pH and these enzyme activities was dependent on the culture medium, which suggested that the expression level and balance of isozyme rely on the culture substrate.
  • Akter M, Shiraishi A, Kumura H, Hayakawa T, Wakamatsu JI
    Animal science journal = Nihon chikusan Gakkaiho 90 6 774 - 780 2019年06月 [査読有り][通常論文]
  • Jun-ichi Wakamatsu, Mofassara Akter, Fumika Honma, Toru Hayakawa, Haruto Kumura, Takanori Nishimura
    LWT 101 599 - 606 Elsevier {BV} 2019年03月 [査読有り][通常論文]
  • Kumura, H., Ohtsuyama, T., Matsusaki, Y.-H., Taitoh, M., Koyanagi, H., Kobayashi, K., Hayakawa, T., Wakamatsu, J.-I., Ishizuka, S.
    Journal of Food Processing and Preservation 42 10 2018年 [査読有り][通常論文]
  • Koichi Ojima, Emi Ichimura, Yuya Yasukawa, Mika Oe, Susumu Muroya, Takahiro Suzuki, Jun-ichi Wakamatsu, Takanori Nishimura
    ANIMAL SCIENCE JOURNAL 88 11 1788 - 1793 2017年11月 [査読有り][通常論文]
     
    In striated muscles, approximately 300 myosin molecules form a single thick filament in myofibrils. Each myosin is continuously displaced by another myosin to maintain the thick filament structure. Our previous study using a fluorescence recovery after photobleaching (FRAP) technique showed that the myosin replacement rate is decreased by inhibition of protein synthesis, but myosin is still exchangeable. This result prompted us to examine whether myosin in the cytoplasm is involved in myosin replacement in myofibrils. To address this, FRAP was measured in green fluorescent protein (GFP)-tagged myosin heavy chain 3 (Myh3) expressing myotubes that were treated with streptolysin-O (SLO), which forms pores specifically in the plasma membrane to induce leakage of cytoplasmic proteins. Our biochemical data demonstrated that the cytoplasmic myosin content was reduced in SLO-permeabilized semi-intact myotubes. Furthermore, FRAP experiments showed a sluggish substitution rate of GFP-Myh3 in SLO-permeabilized myotubes. Taken together, these results demonstrate that the myosin substitution rate is significantly reduced by a decreased amount of myosin in the cytoplasm and that cytoplasmic myosin contributes to myosin replacement in myofibrils.
  • Wenjing Yan, Chihiro Kanno, Eiki Oshima, Yukiko Kuzuma, Sung Woo Kim, Hanako Bai, Masashi Takahashi, Yojiro Yanagawa, Masashi Nagano, Jun-ichi Wakamatsu, Manabu Kawahara
    ANIMAL REPRODUCTION SCIENCE 185 195 - 204 2017年10月 [査読有り][通常論文]
     
    Improving sperm motility and viability are major goals to improve efficiency in the poultry industry. In this study, the effects of supplemental dietary turmeric by-product (TBP) from commercial turmeric production on sperm motility, viability, and antioxidative status were examined in domestic fowl. Mature Rhode Island Red roosters were divided into two groups controls (group C) without TBP administration and test subjects (group T) fed a basal diet supplemented with 0.8 g of TBP/day in a temperature-controlled rearing facility (Experiment 1) and 1.6 g/day under heat stress (Experiment 2) for 4 weeks. In Experiment 1, TBP dietary supplementation increased the sperm motility variables straight-line velocity, curvilinear velocity, and linearity based on a computer-assisted semen analysis, 2 weeks following TBP supplementation. In Experiment 2, using flow cytometry, sperm viability at 3 and 4 weeks following TBP supplementation was greater in Group T than C, and this increase was consistent with a reduction in reactive oxygen species (ROS) production at 2 and 4 weeks. The results of both experiments clearly demonstrate that dietary supplementation with TBP enhanced sperm motility in the controlled-temperature conditions as well as sperm viability, and reduced ROS generation when heat stress prevailed. Considering its potential application in a range of environments, TBP may serve as an economical and potent antioxidant to improve rooster fertility.
  • Misako Ezoe, Jun-ichi Wakamatsu, Yoshihisa Takahata, Takanori Hasegawa, Fumiki Morimatsu, Takanori Nishimura
    JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY 62 2 93 - 100 2016年04月 [査読有り][通常論文]
     
    We compared the effects of purified meat proteins on postprandial thermogenesis and on the secretion of and responsiveness to thyroid hormones (THs) in rats. Body temperatures at 2 h after feeding were significantly higher in the chicken and mutton protein groups than in the other groups, and these proteins seem to have a strong thermogenic effect. There were no significant differences in plasma TH concentrations among the groups, but levels of TH-responsive Spot 14 protein in the liver and brown adipose tissue were significantly higher in the chicken and mutton protein groups than in the other groups. Levels of malic enzyme 1 protein in the liver and brown adipose tissue were significantly higher in the chicken protein group than in the other groups except for the mutton protein group. Furthermore, levels of uncoupling protein 1 were higher in the chicken and mutton protein groups than in the other groups. The results suggest that the difference in postprandial thermogenesis of meat is strongly dependent on meat proteins; chicken and mutton proteins are strong promoters of postprandial thermogenesis, and THs may contribute to this effect. Since strong postprandial thermogenesis and high expression levels of TH target genes and their products were not observed in the amino acid group, chicken and mutton proteins or their digested peptides might contribute to these effects.
  • 若松純一, 加藤亜也奈, 江副美紗子, 西邑隆徳
    日本畜産学会報 86 4 481 - 489 2015年11月25日 [査読有り][通常論文]
  • Koichi Ojima, Emi Ichimura, Yuya Yasukawa, Jun-ichi Wakamatsu, Takanori Nishimura
    AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY 309 10 C669 - C679 2015年11月 [査読有り][通常論文]
     
    Highly organized thick filaments in skeletal muscle cells are formed from similar to 300 myosin molecules. Each thick-filament-associated myosin molecule is thought to be constantly exchanged. However, the mechanism of myosin replacement remains unclear, as does the source of myosin for substitution. Here, we investigated the dynamics of myosin exchange in the myofibrils of cultured myotubes by fluorescent recovery after photo-bleaching and found that myofibrillar myosin is actively replaced with an exchange half-life of similar to 3 h. Myosin replacement was not disrupted by the absence of the microtubule system or by actomyosin interactions, suggesting that known cytoskeletal systems are dispensable for myosin substitution. Intriguingly, myosin replacement was independent of myosin binding protein C, which links myosin molecules together to form thick filaments. This implies that an individual myosin molecule rather than a thick filament functions as an exchange unit. Furthermore, the myosin substitution rate was decreased by the inhibition of protein synthesis, suggesting that newly synthesized myosin, as well as preexisting cytosolic myosin, contributes to myosin replacement in myofibrils. Notably, incorporation and release of myosin occurred simultaneously in myofibrils, but rapid myosin release from myofibrils was observed without protein synthesis. Collectively, our results indicate that myosin shuttles between myofibrils and the nonmyofibrillar cytosol to maintain a dynamic equilibrium in skeletal muscle cells.
  • Toru Hayakawa, Yuri Yoshida, Masanori Yasui, Toshiaki Ito, Jun-ichi Wakamatsu, Akihito Hattori, Takanori Nishimura
    JOURNAL OF FOOD SCIENCE 80 8 C1641 - C1645 2015年08月 [査読有り][通常論文]
     
    The gelation of myosin has a very important role in meat products. We have already shown that myosin in low ionic strength solution containing l-histidine forms a transparent gel after heating. To clarify the mechanism of this unique gelation, we investigated the changes in the nature of myosin subfragments during heating in solutions with low and high ionic strengths with and without l-histidine. The hydrophobicity of myosin and heavy meromyosin (HMM) in low ionic strength solution containing l-histidine was lower than in high ionic strength solution. The SH contents of myosin and HMM in low ionic strength solution containing l-histidine did not change during the heating process, whereas in high ionic strength solution they decreased slightly. The heat-induced globular masses of HMM in low ionic strength solution containing l-histidine were smaller than those in high ionic strength solution. These findings suggested that the polymerization of HMM molecules by heating was suppressed in low ionic strength solution containing l-histidine, resulting in formation of the unique gel. Practical Application The heat-induced gelation of myosin has an important role in meat products and contributes to its quality. Our previous study showed the unique gelation of myosin in low ionic strength solution with l-histidine was different from gelation already known. Understanding the mechanism of this unique gelation of myosin in low ionic strength solution with histidine will lead to development of new meat-based products and to innovation in the meat industry.
  • Jun-ichi Wakamatsu, Naoko Murakami, Takanori Nishimura
    ANIMAL SCIENCE JOURNAL 86 5 547 - 552 2015年05月 [査読有り][通常論文]
     
    The objective of this study was to obtain fundamental data for improving the color of meat products by using animal by-products. We investigated zinc protoporphyrin IX (ZnPP)-forming properties of various internal organs from pigs and chickens. ZnPP was formed in the liver, heart and kidney, whereas the porcine spleen and bile, which are involved in the metabolism of heme, did not have ZnPP-forming properties. The optimum pH values were different among the internal organs and the ZnPP-forming properties of porcine organs were better than those of chicken organs. The porcine liver showed the greatest ZnPP-forming properties among all of the internal organs investigated in this study. The optimum pH value for ZnPP formation in the liver was lower than that of skeletal muscle. Oxygen did not inhibit the formation of ZnPP in the liver, unlike in skeletal muscle. Animal by-products such as the liver have good ability for the formation of ZnPP and might be useful for improving the color of meat products.
  • Mohamed A. A. Mahdy, Hsiao Yin Lei, Jun-Ichi Wakamatsu, Yoshinao Z. Hosaka, Takanori Nishimura
    ANNALS OF ANATOMY-ANATOMISCHER ANZEIGER 202 18 - 27 2015年 [査読有り][通常論文]
     
    In the present study, we examined muscle regeneration following two types of chemical injuries, cardiotoxin (CTX) and glycerol, in order to compare their effect on the morphological characteristics during muscle regeneration, in addition we studied the structural changes of the intramuscular connective tissue (IMCT) during the regeneration process, by scanning electron microscopy (SEM) after digestion of the cellular elements of the muscle with sodium hydroxide. Tibialis anterior (TA) muscles of adult male mice were injected either with CTX or glycerol. Muscle degeneration was greater in the CTX-injured model than in the glycerol-injured model at day 4 post injection. Muscle regeneration started at day 7 in both the CTX and glycerol models. However, the CTX-injured model showed a higher myotube density and larger myotube diameter than the glycerol-injured model at days 10 and 14 post injection. On other hand, adipocyte infiltration was detected in the glycerol-injured model. In contrast, no adipocytes could be detected in the CTX-injured model. Furthermore, ultrastructural analysis showed a significant difference in myofiber damage and regeneration between the two models. SEM of the IMCT showed a transient increase in endomysial collagen deposition at early stages of. regeneration in the CTX-injured model. In contrast, glycerol-injured model showed slight endomysial collagen deposition. Our results suggest that changes in IMCT affect the efficiency of muscle regeneration. Studying the three dimensional structure of IMCT may help clinical therapies to reduce skeletal muscle fibrosis. To our knowledge this is the first time the changes in IMCT following CTX and glycerol injury using SEM-cell maceration technique have been compared. (c) 2015 Elsevier GmbH. All rights reserved.
  • Jun-ichi Wakamatsu, Naomasa Takabayashi, Misako Ezoe, Takanori Hasegawa, Tatsuya Fujimura, Yoshihisa Takahata, Fumiki Morimatsu, Takanori Nishimura
    JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY 59 6 516 - 525 2013年12月 [査読有り][通常論文]
     
    We investigated the postprandial thermic effect of chicken and its mechanisms in rats. A chicken diet showed a strong thermic effect after consumption, and the removal of fat induced more rapid and stronger thermogenesis. Although thermogenesis induced by a purified chicken protein diet was also strong, the thermic reaction was not so rapid and a remarkable rise of peripheral temperatures was not observed. Defatted chicken and purified chicken protein activated the thyroid hormone system and up-regulated rate-limiting enzyme genes of glucose metabolism and the tricarboxylic acid (TCA) cycle in the liver. Moreover, chicken protein up-regulated the mRNA expression of a rate-limiting enzyme of hepatic lipid metabolism. It is possible that the mechanisms by which body temperature is raised are different between chicken protein and defatted chicken. On the other hand, it is possible that chicken fat suppressed the expression of energy metabolism-related genes that was induced by the consumption of lean chicken. As a result, a rise of postprandial body temperature might not have been induced after consumption of chicken fat. These results suggest that the consumption of lean chicken activates the thyroid hormone system and hepatic energy metabolism and consequently induces the postprandial thermic effect of chicken.
  • Keisuke Suzuki, Yasuhiro Kishioka, Jun-Ichi Wakamatsu, Takanori Nishimura
    Animal Science Journal 84 9 669 - 674 2013年09月 [査読有り][通常論文]
     
    Decorin, a small leucine-rich proteoglycan, plays an important role in cellular activities through modification of growth factors. It also acts as a signaling molecule to non-muscle cells through epidermal growth factor receptor or insulin-like growth factor I receptor (IGF-IR). However, it is unclear if decorin acts as a signaling molecule to myogenic cells. In this study, we investigated the effect of decorin on the differentiation of myoblasts and the signaling via IGF-IR to myogenic cells. C2C12 myoblasts cultured in media containing decorin for 72h showed more extensive formation of multinucleated myotubes than control cells cultured in the same media without decorin. The protein expressions of myogenin and myosin heavy chian were higher in decorn-treated cells than in control cells. These results suggest that decorin enhances the differentiation of myoblasts. Western blot analysis and immunocytochemistry showed that IGF-IR was expressed in myoblasts and myotubes. Furthermore, Akt, which is downstream of IGF-IR, was more phosphorylated in myoblasts cultured in media containing decorin than those in media without decorin. These results suggest that decorin activates Akt downstream of IGF-IR and enhances the differentiation of myogenic cells. © 2013 Japanese Society of Animal Science.
  • Naofumi Yasaka, Keisuke Suzuki, Yasuhiro Kishioka, Jun-ichi Wakamatsu, Takanori Nishimura
    ANIMAL SCIENCE JOURNAL 84 9 663 - 668 2013年09月 [査読有り][通常論文]
     
    Myostatin is a growth and differentiation factor and acts as a negative regulator of skeletal muscle mass. Although the mechanism whereby myostatin controls muscle cell growth is mostly clarified, the regulation of myostatin activity after its secretion into the extracellular matrix (ECM) is still unclear. In the present study, we investigated the interaction between laminin and myostatin and the effect of laminin on myostatin signaling in vitro. The surface plasmon resonance assay showed that laminin bound to mature myostatin and activin receptor type IIB (ActRIIB), but did not bind to latency-associated protein, which remains non-covalently linked to mature myostatin. Furthermore, kinetic analysis demonstrated that the affinity of mature myostatin for laminin was similar to that for ActRIIB. Next, we examined the action of laminin on the myostatin signaling pathway using a conventional reporter assay. The luciferase activity of myostatin-treated cells was repressed significantly (P < 0.05) by coincubation of laminin. These results suggest that laminin has a potential to regulate myostatin activity through binding to mature myostatin and/or its receptor ActRIIB.
  • Jun-ichi Wakamatsu, Ryoji Fujii, Kimikazu Yamaguchi, Syouhei Miyoshi, Takanori Nishimura, Akihito Hattori
    ANIMAL SCIENCE JOURNAL 84 5 416 - 425 2013年 [査読有り][通常論文]
     
    We examined animal species differences in the postprandial thermic effect of meat and investigated the postprandial thermic effect of mutton in rats. After intake of experimental diets containing each meat, body temperatures of rats fed mutton or venison were significantly higher than that of rats fed rabbit meat. After intake of experimental diets containing fractionized mutton, the body temperatures of rats fed diets containing lean mutton protein were higher than those of rats fed diets without lean mutton protein. In a two-dimensional fluorescence difference gel electrophoresis study of brown adipose tissue, it was shown that the intake of mutton up-regulated the expression of many signaling molecules that are involved in energy metabolism. The postprandial thermic effect of mutton seems to be due not to catecholamine and adrenocorticotropic hormone but to thyroid hormones. The results suggest that intake of lean mutton protein stimulates the secretion of thyroid hormones and facilitates energy metabolism in rats.
  • Yoshinao Z. Hosaka, Mika Ishibashi, Jun-ichi Wakamatsu, Masato Uehara, Takanori Nishimura
    BIOMEDICAL RESEARCH-TOKYO 33 6 355 - 361 2012年12月 [査読有り][通常論文]
     
    The aim of this study was to clarify the effects of myostatin, which is a negative regulator of skeletal muscle mass, on the proliferation of NIH3T3 fibroblasts and the synthesis of extracellular matrix (ECM) by them. A proliferation assay revealed that myostatin attenuated cell growth at any of the doses used. High doses of myostatin strongly inhibited cell proliferation. Moreover, myostatin receptor, activin receptor type-2B (ActRIIB), was found to be distributed on cells and it was also clarified that myostatin increased the expression of cyclin-dependent kinase inhibitor p21 (p21). These results suggested that a high dose of myostatin inhibits fibroblast proliferation by the same mechanism as that for inhibition of myoblast proliferation. We then examined the effects of myostatin on the mRNA expression of ECM molecules (decorin, biglycan, type I collagen, type III collagen, type IV collagen and type V collagen) by real-time PCR. Real-time PCR showed that myostatin increased the mRNA of decorin, biglycan and collagen (types I, IV and V) in fibroblasts. The results suggest that myostatin regulates ECM synthesis in cultured fibroblasts.
  • T. Hayakawa, Y. Yoshida, M. Yasui, T. Ito, T. Iwasaki, J. Wakamatsu, A. Hattori, T. Nishimura
    MEAT SCIENCE 90 1 77 - 80 2012年01月 [査読有り][通常論文]
     
    Binding properties are important for meat products and are substantially derived from the heat-induced gelation of myosin. We have shown that myosin is solubilized in a low ionic strength solution containing L-histidine. To clarify its processing characteristics, we investigated properties and structures of heat-induced gels of myosin solubilized in a low ionic strength solution containing t-histidine. Myosin in a low ionic strength solution formed transparent gels at 40-50 degrees C, while myosin in a high ionic strength solution formed opaque gels at 60-70 degrees C. The gel of myosin in a low ionic strength solution with t-histidine showed a fine network consisting of thin strands and its viscosity was lower than that of myosin in a high ionic strength solution at 40-50 degrees C. The rheological properties of heat-induced gels of myosin at low ionic strength are different from those at high ionic strength. This difference might be caused by structural changes in the rod region of myosin in a low ionic strength solution containing t-histidine. (C) 2011 Elsevier Ltd. All rights reserved.
  • 高萩陽一, 岩渕修, 助川慎, 中胡隆, 越田雄三, 若松純一, 藤村達也, 石黒智子, 村上博, 飯村裕二, 小林泰男, 森松文毅, 川島知之, 菱沼毅
    日本畜産学会報 82 3 325 - 331 Japanese Society of Animal Science 2011年08月 [査読有り][通常論文]
     
    ホエイは牛乳からナチュラルチーズを製造する際に大量に生成される.本試験では国内商用豚生産農場にて繁殖雌豚,哺乳期肉豚および肥育期肉豚に対して液状ストレートホエイを通常飼料に付加する形で一定量給与し,その繁殖成績や発育成績および枝肉形質に対する効果を検証した.繁殖雌豚へ1日3-5 Lの液状ストレートホエイ給与によって一腹産子数,離乳後7日以内再発情率および受胎率がそれぞれ有意に0.2頭,3.2%および3.4%改善した.肥育期肉豚に1日1.3-1.5 Lの液状ストレートホエイを給与した場合,出荷日齢が有意に3.4日短縮することが確認された.一方,肉豚の哺乳期のみ1日0.2 Lの液状ストレートホエイ給与ではその後の発育成績の改善は認められなかった.以上の結果から,商用豚生産農場において繁殖雌豚や肥育期の肉豚に適切な量の液状ストレートホエイを給与すれば繁殖成績や発育成績の改善が期待できることがわかった.
  • Yasuo Kobayashi, Aya Itoh, Kanae Miyawaki, Satoshi Koike, Osamu Iwabuchi, Yuji Iimura, Yuri Kobashi, Tomoyuki Kawashima, Junichi Wakamatsu, Akihito Hattori, Hiroshi Murakami, Fumiki Morimatsu, Takashi Nakaebisu, Takeshi Hishinuma
    ANIMAL SCIENCE JOURNAL 82 4 607 - 615 2011年 [査読有り][通常論文]
     
    The effect of liquid whey feeding on fecal bacteria and their metabolites was assessed in five pregnant sows and 66 growing pigs. Sows were fed a control diet for 4 weeks (control period) followed by the same diet but with whey feeding (5 L/day/pig) for 4 weeks (whey period). One group of growing pigs was given 267 L of whey per pig (whey group), while the other group was not (control group). In both cases, liquid whey was given separately from control diet. Sows in the whey period had feces showing lower pH, lower ammonia concentration, and larger population sizes of total bacteria, lactobacilli and bifidobacteria. The bacterial gene library analysis indicated that Mitsuokella and Megasphaera were more frequently detected, while Clostridium disporicum were detected less frequently in the whey period. Feces from whey-fed growing pigs showed lower pH than that from control pigs in the early stage of growing. Also, larger populations of total bacteria, lactobacilli and bifidobacteria were recorded in the whey group. From the bacterial gene library analysis, the detection frequency of Lactobacillus reuteri tended to be higher in the whey group. These results indicate that whey feeding influences the hindgut microbiota of pigs, possibly leading to a fermentation shift that is favorable for animal health.
  • T. Hayakawa, T. Ito, J. Wakamatsu, T. Nishimura, A. Hattori
    MEAT SCIENCE 84 4 742 - 746 2010年04月 [査読有り][通常論文]
     
    Myosin, one of the major myofibrillar proteins, forms a filamentous polymer and is insoluble in physiological and low ionic strength solutions. We have shown that myosin is soluble in a low ionic strength solution containing L-histidine. In this study, to clarify the role of L-histidine in the solubilization of myosin, we investigated effects of L-histidine on the filament formation and the morphology of myosin at a low ionic strength. In the presence of L-histidine, myosin formed a filamentous polymer in a physiological ionic strength solution and dispersed in a low ionic strength solution. Transmission electron microscopy showed that light meromyosin (LMM), the rod region of myosin, in a low ionic strength solution containing L-histidine was longer than that in a high ionic strength solution without L-histidine. L-histidine causes the elongation of LMM region of myosin contributing to the weakening of the myosin filament and the dissociation of myosin in a low ionic strength solution. (C) 2009 Elsevier Ltd. All rights reserved.
  • Takayuki Miura, Yasuhiro Kishioka, Jun-ichi Wakamatsu, Akihito Hattori, Takanori Nishimura
    ANIMAL SCIENCE JOURNAL 81 1 102 - 107 2010年 [査読有り][通常論文]
     
    Myostatin, a member of the TGF-beta superfamily, is a negative regulator of skeletal muscle mass. We have recently demonstrated that decorin binds to myostatin in vitro, and that immobilized decorin within the collagen matrix prevents myostatin-mediated inhibition of myoblast proliferation. However, little is known about other ECM molecules that bind to myostatin and modulate its activity. Thus, in the present study, we investigated the interaction of several other ECM molecules with myostatin. We here show that fibromodulin, fibronectin and laminin bind to myostatin in the presence of Zn(2+) with a dissociation constant (K(D) ) of 10(-10)similar to 10(-8) mol/L. Fibromodulin shows the highest affinity for myostatin among them. These results suggest that these ECM molecules may modulate myostatin activity like decorin does.
  • Jun-ichi Wakamatsu, Nobutaka Hayashi, Takanori Nishimura, Akihito Hattori
    MEAT SCIENCE 84 1 125 - 128 2010年01月 [査読有り][通常論文]
     
    The aim of this study was to elucidate the mechanism by which curing agents, especially nitrite, inhibit the formation of zinc protoporphyrin IX (ZPP) in dry-cured hams such as Parma ham. The oxidation-reduction potential of model solutions was increased by the addition of nitrite, but it was not clear whether the formation of ZPP is inhibited by the oxidizing property of nitrite. The effect of nitric oxide (NO) produced from nitrite on the formation of ZPP was examined. The amount of ZPP formed was decreased by the addition of NO donors. The amount of protoporphyrin IX (PPIX), which is the precursor of ZPP, was also decreased by the addition of NO donors. It is concluded that NO produced from nitrite inhibited the formation of PPIX and ZPP was therefore not formed in cured meat products with the addition of nitrite or nitrate. (C) 2009 Elsevier Ltd. All rights reserved.
  • Effect of L-histidine and ionic strength on disassembly of myosin filaments
    Proceeding ICoMST2010 B026  2010年 [査読無し][通常論文]
  • Thermic effect of chicken
    Proceeding ICoMST2010 B026  2010年 [査読無し][通常論文]
  • 小橋 有里, 石黒 智子, 若松 純一, 奥村 朋之, 高萩 陽一, 岩渕 修, 飯村 裕二, 川島 知之, 小林 泰男, 服部 昭仁, 村上 博, 森松 文毅
    日本畜産學會報 = The Japanese journal of zootechnical science 80 4 443 - 450 社団法人日本畜産学会 2009年11月 [査読有り][通常論文]
     
    乳業工場から排出された液状ホエーを通常飼料に付加的に給与し,豚肉生産試験を行った.9腹の離乳豚66頭を通常飼料のみで飼育した対照区(CN区)と通常飼料に液状ホエーを付加的に給与したホエー区(Whey区)に母豚効果を配慮して分けた.Whey区には試験期間を通して267 L/頭の液状ホエーを給与した.両区は経時的に体重測定を行い,出荷直前に採血をして自然免疫の状態を比較した.平均体重は65日齢と173日齢でWhey区の方が有意に高かった(P < 0.05).日増体量はWhey区の方が生後29-65日の期間(P < 0.01)と105-173日の期間(P < 0.05)で有意に高かった.また,枝肉成績およびロース肉の理化学的特性はWhey区とCN区とで有意差は認められず,自然免疫状態についても有意差がなかった.以上の結果から,液状ホエー給与は枝肉成績および肉質に影響を与えることなくブタの出荷日齢を短縮する傾向にあり,生産性向上に有効であることが示された.
  • T. Hayakawa, T. Ito, J. Wakamatsu, T. Nishimura, A. Hattori
    MEAT SCIENCE 82 2 151 - 154 2009年06月 [査読有り][通常論文]
     
    Myosin, one of the major myofibrillar proteins, is insoluble at low and physiological ionic strength and soluble at high ionic strength. In this study, the behavior and morphology of myosin solubilized in a low ionic strength Solution containing L-histidine (L-His) was investigated. More than 80% of myosin was solubilized in a low ionic strength solution with dialysis against a solution containing 1 mM KCl and 5 MM L-His. Transmission electron microscopy with rotary shadowing demonstrated that the rod of myosin in a low ionic strength solution containing L-His is longer than that of myosin in a high ionic strength solution. The elongation of the myosin rod in a low ionic strength solution containing L-His would inhibit the formation of a filament, resulting in the solubilization of myosin. (c) 2009 Elsevier Ltd. All rights reserved.
  • Jun-ichi Wakamatsu, Hiroko Odagiri, Takanori Nishimura, Akihito Hattori
    MEAT SCIENCE 82 1 139 - 142 2009年05月 [査読有り][通常論文]
     
    We measured the contents of Zn protoporphyrin IX (ZPP), heme and protoporphyrin IX (PPIX) in Parma ham by simultaneous analysis using high-performance liquid chromatography (HPLC). Extraction with ethyl acetate-acetic acid (4:1) was suitable for the quantitative analysis of ZPP. The contents of heme, ZPP and PPIX in Parma ham were 15.0-29.9, 27.7-47.0 and 0.4-1.1 mu g/g, respectively, and total content of porphyrin was 43.7-76.6 mu g/g. The amount of ZPP in Parma ham was larger than that of heme, and ZPP accounted for 60-70% of all porphyrins. (c) 2008 Elsevier Ltd. All rights reserved.
  • Jun-Ichi Wakamatsu, Juichi Uemura, Hiroko Odagiri, Jun Okui, Nobutaka Hayashi, Shoji Hioki, Takanori Nishimura, Akihito Hattori
    ANIMAL SCIENCE JOURNAL 80 2 198 - 205 2009年04月 [査読有り][通常論文]
     
    Zinc protoporphyrin IX (ZPP) is a characteristic red pigment in meat products that are manufactured without the addition of a curing agent such as nitrate or nitrite. To examine the effects of impurities such as mineral components in sea salt on the formation of ZPP, we manufactured Parmatype dry-cured hams that were salted with refined salt or sea salt and examined the involvement of oxidation-reduction potential (ORP) in the formation of ZPP. The content of ZPP was increased drastically after 40 weeks. Microscopic observation showed strong fluorescence caused by ZPP muscle fiber after 40 weeks. Conversely, heme content varied considerably during processing. ORP increased during processing. However, there was no obvious difference between ham salted with refined salt and that salted with sea salt. Therefore, it was concluded that impurities in sea salt were not involved in the formation of ZPP.
  • Takanori Nishimura, Suhong Fang, Jun-ichi Wakamatsu, Koui Takahashi
    ANIMAL SCIENCE JOURNAL 80 1 85 - 90 2009年02月 [査読有り][通常論文]
     
    We studied the relationships between the shear-force value and physical and structural properties of the intramuscular connective tissue (IMCT) in six classes of porcine skeletal muscle to elucidate the contribution of IMCT to toughness of raw pork. The shear-force value of raw pork correlated significantly with that of the IMCT model prepared from each class of skeletal muscle (P < 0.05). The correlation suggested that the variable toughness of pork was caused by the mechanical strength of the endomysium and perimysium. The thickness of the secondary perimysium correlated significantly with the shear-force value of raw pork (P < 0.05) and with that of the IMCT model (P < 0.05). The shear-force value of raw pork correlated significantly with the total amount of collagen (P < 0.05) but not with the heat-solubility of collagen. We concluded therefore that the thickness of the secondary perimysium determines the mechanical strength of IMCT and contributes to toughness in raw pork.
  • Takanori Nishimura, Suhong Fang, Toshiaki Ito, Jun-ichi Wakamatsu, Koui Takahashi
    ANIMAL SCIENCE JOURNAL 79 6 716 - 721 2008年12月 [査読有り][通常論文]
     
    We studied structural changes in the endomysium and perimysium during postmortem aging of pork using the cell-maceration/scanning electron microscope method. Immediately post mortem, endomysia sheaths that house individual muscle fibers displayed a honeycomb-like structure. The sheaths of the endomysium consisted of tightly arranged collagen fibrils in a random network. The perimysium comprised several layers of wavy sheets made up of tightly bundled collagen fibers. While the structure of the intramuscular connective tissues remained almost unchanged up to five days post mortem, the endomysium had resolved into individual collagen fibrils, and the thick sheets of the perimysium had separated into collagen fibers and fibrils at 8 days post mortem. These results provide direct evidence for structural weakening of the endomysium and perimysium during postmortem aging of pork. The shear-force value of raw pork decreased rapidly within six days post mortem and then decreased slowly until 14 days post mortem. Since the rapid increase in tenderness is mainly due to structural weakening of myofibrils, we conclude that the disintegration of the endomysium and perimysium contributes to tenderization of pork during extended postmortem aging.
  • Yasuhiro Kishioka, Mark Thomas, Jun-Ichi Wakamatsu, Akihito Hattori, Mridula Sharma, Ravi Kambadur, Takanori Nishimura
    JOURNAL OF CELLULAR PHYSIOLOGY 215 3 856 - 867 2008年06月 [査読有り][通常論文]
     
    Decorin, a small leucine-rich proteoglycan, plays an important role in the regulation of cell growth. Our recent study has shown that immobilized decorin in the collagen matrix sequesters myostatin into the extracellular matrix and prevents its inhibitory action to myoblast proliferation in vitro. However, it still remains unclear whether free decorin could affect the proliferation and differentiation of myogenic cells by regulating myostatin activity. In the present study, we generated stable clonal C2C 12 myoblasts that were over-expressing decorin, and showed that decorin over-expressing cells had an increased rate of proliferation as compared to control cells. Decorin over-expressing cells formed multi-giant hypertrophic myotubes with an elongated morphology and larger size as compared to control cells, although the initiation of differentiation in decorin over-expressing cells was somewhat delayed as compared to control cells. Western blot analysis demonstrated that MyoD expression in decorin over-expressing cells was lower than that in control cells until 12 h after induction to differentiate. At 48-h differentiation, the expressions of MyoD, p21 and myogenin were dramatically increased in cells that over-expressed decorin. Furthermore, we revealed that over-expression of decorin suppressed the activity of myostatin endogenously synthesized in C2C 12 myoblasts and attenuated the signaling of exogenous myostatin. Consistent with these results, knockdown of decorin impairs C2C 12 myoblast growth by increasing the sensitivity to exogenous myostatin. These results clearly show that decorin enhances the proliferation and differentiation of C2C 12 myoblasts through suppressing myostatin activity.
  • Takanori Nishimura, Kenjiro Nozu, Yasuhiro Kishioka, Jun-ichi Wakamatsu, Akihito Hattori
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 370 3 383 - 387 2008年06月 [査読有り][通常論文]
     
    Satellite cells are quiescent muscle stem cells that promote postnatal muscle growth and repair. When satellite cells are activated by myotrauma, they proliferate, migrate, differentiate, and ultimately fuse to existing myofibers. The remainder of these cells do not differentiate, but instead return to quiescence and remain in a quiescent state until activation begins the process again. This ability to maintain their own population is important for skeletal muscle to maintain the capability to repair during postnatal life. However, the mechanisms by which satellite cells return to quiescence and maintain the quiescent state are still unclear. Here, we demonstrated that decorin mRNA expression was high in cell cultures containing a higher ratio of quiescent satellite cells when satellite cells were stimulated with various concentrations of hepatocyte growth factor. This result suggests that quiescent satellite cells express decorin at a high level compared to activated satellite cells. Furthermore, we examined the expression of decorin in reserve cells, which were undifferentiated myoblasts remaining after induction of differentiation by serum-deprivation. Decorin mRNA levels in reserve cells were higher than those in differentiated myotubes and growing myoblasts. These results suggest that decorin participates in the quiescence of myogenic cells. (c) 2008 Elsevier Inc. All rights reserved.
  • Takanori Nishimura, Kazuki Nakamura, Yasuhiro Kishioka, Yuko Kato-Mori, Jun-ichi Wakamatsu, Akihito Hattori
    JOURNAL OF MUSCLE RESEARCH AND CELL MOTILITY 29 1 37 - 44 2008年01月 [査読有り][通常論文]
     
    Skeletal muscle satellite cells are quiescent stem cells that localized between the plasmalemma and the basement membrane of muscle fiber. When muscle is injured, satellite cells are activated, migrate to the injured site and contribute to the regeneration of muscle. However, little is known about the mechanism by which satellite cells migrate underneath the basement membrane. To clarify this, we investigated the effect of MMP inhibition on the migration of C2C12 muscle cells in vitro using a time-lapse imaging system. The migration speed of cells cultured with an MMP-inhibitor reagent was significantly lower (P < 0.01) than the control cultured without an inhibitor reagent. The persistency index was significantly higher (P < 0.01) in cells cultured with an inhibitor than in those without an inhibitor. Furthermore, MMP-3 knockdown cells migrated faster than control cells. These results strongly suggest that MMPs synthesized in skeletal muscle cells play an important role in the migration of these cells.
  • Jun-ichi Wakamatsu, Jun Okui, Nobutaka Hayashi, Takanori Nishimura, Akihito Hattori
    MEAT SCIENCE 77 4 580 - 586 2007年12月 [査読有り][通常論文]
     
    We examined the effects of exogenous myoglobin, a bivalent chelator, and nitrite on Zn protoporphyrin IX (ZPP) formation by using model systems. ZPP was formed in a model solution without addition of exogenous myoglobin. After incubation, the amount of ZPP in a model solution was increased but that of heme was not decreased compared with the amounts before incubation. Protoporphyrin IX (PPIX) instead of ZPP also accumulated in a model solution with addition of EDTA, but the amount of heme was not reduced. These results suggested that ZPP was not formed by the Fe-Zn substitution in heme but was formed by the insertion of Zn into PPIX, which was formed independently. The fact that the effects of various factors in model systems with/without addition of a bivalent chelator were similar suggested that ZPP formation was strongly affected by PPIX formation. Inhibition of PPIX formation by nitrite might be the reason for the low levels of ZPP in cured meats. (C) 2007 Elsevier Ltd. All rights reserved.
  • Takanori Nishimura, Kohei Oyama, Yasuhiro Kishioka, Jun-ichi Wakamatsu, Akihito Hattori
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 361 4 896 - 902 2007年10月 [査読有り][通常論文]
     
    Decorin, a small leucine-rich proteoglycans, plays an important role in tissue morphogenesis through the regulation of collagen fibrillogenesis and the modulation of some growth factors. Our recent study has shown that decorin binds to myostatin, a negative regulator of skeletal muscle mass, and modulates its inhibitory action to myogenic cell growth in vitro. However, it still remains unclear whether decorin binds to myostatin in vivo during the development of skeletal muscle. To clarify this, we investigated the spatiotemporal expression of decorin and myostatin in rat skeletal muscle by RT-PCR and immunohistochemistry. Decorin mRNA abundance in fetal skeletal muscle was significantly higher than those in neonates and adults (P < 0.05). Decorin mRNA expression decreased drastically at birth, and thereafter gradually up to 9 weeks of age. The mRNA expression pattern of myostatin was quite similar to that of decorin during prenatal and postnatal development of rat skeletal muscle. Immunohistochemical analysis demonstrated that myostatin was located in the muscle fibers, and that decorin was located in the periphery of muscle fibers in fetal rat skeletal muscle. Taken together with our previous data, these results suggest that decorin binds myostatin and sequesters it in the ECM during the development of rat skeletal. (C) 2007 Elsevier Inc. All rights reserved.
  • Jun-ichi Wakamatsu, Toshiaki Ito, Takanori Nishimura, Akihito Hattori
    MEAT SCIENCE 76 2 385 - 387 2007年06月 [査読有り][通常論文]
     
    We studied the presence of zinc in the red pigment extracted from Parma ham by scanning electron microscopy/energy dispersive X-ray microanalysis. The large peak of about 8.6 keV and the small peaks at about 1.1 keV and 9.5 keV were derived from K-alpha L-alpha 1 and K-beta X-ray of zinc, respectively. Thus, the results suggested that zinc existed in the red pigment extracted from Parma ham. In contrast, the K X-ray peak of iron (6.4 keV) was not detected and the K-alpha X-ray peak of magnesium (1.3 keV) was hardly detected. These results revealed that the red pigment contained not iron but zinc. In addition to the results of mass analysis in previous studies, the red pigment was demonstrated to be zinc protoporphyrin IX. (c) 2006 Elsevier Ltd. All rights reserved.
  • J. Wakamatsu, H. Odagiri, T. Nishimura, A. Hattori
    MEAT SCIENCE 74 3 594 - 599 2006年11月 [査読有り][通常論文]
     
    We investigated the distribution of Zn protoporphyrin IX (ZPP) in Parma ham by using purple LED light and image analysis in order to elucidate the mechanism of ZPP formation. Autofluorescence spectra of Parma ham revealed that ZPP was present in both lean meat and fat, while red emission other than that of ZPP was hardly detected. Although ZPP was found to be distributed widely in Parma ham, it was more abundant in intermuscular fat and subcutaneous fat than in lean meat. The intensity of red emission was weak in muscles that were exposed during the processing. ZPP in both lean meat and subcutaneous fat tended to be more abundant in the inner region than in the outer region. It was thought that ZPP is transferred from lean meat to fat tissue during the processing, resulting in the small amount of ZPP in the lean meat adjacent to subcutaneous fat. Our results led to a completely new hypothesis that ZPP is formed in lean meat and transferred to fat tissue. (c) 2006 Elsevier Ltd. All rights reserved.
  • T Miura, Y Kishioka, J Wakamatsu, A Hattori, A Hennebry, CJ Berry, M Sharma, R Kambadur, T Nishimura
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 340 2 675 - 680 2006年02月 [査読有り][通常論文]
     
    Myostatin, a member of TGF-beta superfamily of growth factors, acts as a negative regulator of skeletal muscle mass. The mechanism whereby myostatin controls the proliferation and differentiation of myogenic cells is mostly clarified. However, the regulation of myostatin activity to myogenic cells after its secretion in the extracellular matrix (ECM) is still unknown. Decorin, a small leucine-rich proteoglycan, binds TGF-beta and regulates its activity in the ECM. Thus, we hypothesized that decorin could also bind to myostatin and participate in modulation of its activity to myogenic cells. In order to test the hypothesis, we investigated the interaction between myostatin and decorin by surface plasmon assay. Decorin interacted with mature myostatin in the presence of concentrations of Zn2+ greater than 10 mu M, but not in the absence of Zn2+. Kinetic analysis with a 1:1 binding model resulted in dissociation constants (K-D) of 2.02 x 10(-8) M and 9.36 x 10(-9) M for decorin and the core protein of decorin, respectively. Removal of the glycosaminoglycan chain by chondroitinase ABC digestion did not affect binding, suggesting that decorin could bind to myostatin with its core protein. Furthermore, we demonstrated that immobilized decorin could rescue the inhibitory effect of myostatin on myoblast proliferation in vitro. These results suggest that decorin could trap myostatin and modulate its activity to myogenic cells in the ECM. (c) 2005 Elsevier Inc. All rights reserved.
  • K Shimada, Y Sakuma, J Wakamatsu, M Fukushima, M Sekikawa, K Kuchida, M Mikami
    MEAT SCIENCE 68 3 357 - 362 2004年11月 [査読有り][通常論文]
     
    We have adapted the enzymatic method [Biochemical and Biophysical Research Communications 176 (3) (1991) 1617] for the safe and rapid assay of L-carnitine (L-CA) in skeletal muscle using a microplate reader. The concentration of L-CA in fresh semitendinosus muscle from broiler chicken, pig, beef cattle, deer, horse and goat muscle were 0.69, 1.09, 1.86-3.57, 4.57, 4.95 and 11.36 mumol/g wet weight, respectively. The animals which had higher concentration of L-CA, also had the highest amounts of myoglobin as an index to the redness of the muscle. Furthermore, we investigated this relationship between white muscle, M. pectoralis profundus. and red muscle, M. soleus, in laying hens. The L-CA and myoglobin concentration in red muscle were significantly higher than those in white muscle (p < 0.01). These findings suggest that L-CA concentration in muscle is related to oxygen metabolism and to myofiber types. (C) 2004 Elsevier Ltd. All rights reserved.
  • J Wakamatsu, J Okui, Y Ikeda, T Nishimura, A Hattori
    MEAT SCIENCE 68 2 313 - 317 2004年10月 [査読有り][通常論文]
     
    The aim of this study was to establish a model experiment system to elucidate the mechanism by which Zn-protoporphyrin IX (ZPP) is formed in Parma ham. The established model consisted of myoglobin, meat and antibiotics, and incubation under anaerobic conditions resulted in a greater yield of ZPP. Formation of ZPP was observed even in the presence of various antiseptics. The amount of ZPP formed increased as the period of incubation increased. ZPP formation was inhibited by heating meat homogenate depending on the heating temperature. Our results show that anaerobic conditions are suitable for the formation of ZPP in meat products without nitrate or nitrite and that endogenous enzymes as well as microorganisms may be involved in ZPP formation. (C) 2004 Elsevier Ltd. All rights reserved.
  • J Wakamatsu, T Nishimura, A Hattori
    MEAT SCIENCE 67 1 95 - 100 2004年05月 [査読有り][通常論文]
     
    The Italian traditional dry-cured ham (Parma ham) shows a stable bright red color that is achieved without the use of nitrite and/or nitrate. In this study we examined the pigment spectroscopically, fluoroscopically and by using HPLC and ESI-HR-MASS analysis. Porphyrin derivative other than acid hematin were contained in the HO-containing acetone extract from Parma ham. A strong fluorescence peak at 588 nm and a weak fluorescence peak at 641 mn were observed. By HPLC analysis the acetone extract of Parma ham was observed at the single peak, which eluted at the same time as Zn-protoporphyrin IX and emitted fluorescence. The results of ESI-HR-MS analysis showed both agreement with the molecular weight of Zn-protoporphyrin IX and the characteristic isotope pattern caused by Zn isotopes. These results suggest that the bright red color in Parma ham is caused by Zn-protoporphyrin IX. (C) 2003 Elsevier Ltd. All rights reserved.
  • Yukiko Ito, Shinji Toki, Takashi Omori, Hiroshi Ide, Ryuichi Tatsumi, Jun-Ichi Wakamatsu, Takanori Nishimura, Akihito Hattori
    Animal Science Journal 75 1 59 - 65 2004年02月 [査読有り][通常論文]
     
    The solubility of skeletal muscle myofibrillar proteins in water was examined. The solubility of the proteins was found to be sensitive to ionic strength and pH of the solution. At the ionic strength of less than 12 mM and neutral pH, more than 80% of myofibrillar proteins were solubilized. Heating at a temperature of more than 70°C was required for the proteins to retain their solubility. The solubility of freeze-dried protein powder prepared from water-soluble myofibrillar proteins was also examined, and it was found that addition of trehalose and heating were essential for re-solubilization in water. Amino acid composition of water-soluble myofibrillar proteins was found to be almost the same as that of myofibrillar proteins.
  • Takanori Nishimura, Ayaka Taneichi, Jun-Ichi Wakamatsu, Akihito Hattori
    Animal Science Journal 74 5 399 - 405 2003年10月 [査読有り][通常論文]
     
    The effect of skeletal muscle decorin on collagen fibrillogenesis was investigated, in order to provide background for understanding the functions of decorin in skeletal muscle. The self-assembly of type I and III collagen with the addition of decorin or the core protein of decorin from bovine neonatal skeletal muscle was monitored using a spectrophotmeter. Time course changes in the absorbance of collagen solutions showed typical sigmoidal curves composed of three phases. The time of the initial phase was not different between the collagen solution with decorin and that without decorin. The increase rate of the absorbance in the second phase decreased with concentration of decorin added in collagen solutions. Similar effects on fibrillogenesis of type I and III collagens were observed when the core protein of decorin was added in collagen solutions. These results suggest that regulation of collagen fibrillogenesis by decorin depends on its core protein. The networks of reconstructed collagen fibrils with decorin were looser than those without decorin. Bovine skeletal muscle decorin could participate in the regulation of collagen fibrillogenesis and in the arrangement of collagen fibrils in the intramuscular connective tissue.
  • Yukiko Ito, Ryuichi Tatsumi, Jun-Ichi Wakamatsu, Takanori Nishimura, Akihito Hattori
    Animal Science Journal 74 5 417 - 425 2003年10月 [査読有り][通常論文]
     
    Myofibrillar proteins of vertebrate skeletal muscles are insoluble in solutions of ionic strength that approximate physiological conditions. We established a method to solubilize more than 80% of chicken breast muscle myofibrillar proteins in water for the use of meat as a source of food protein. SDS-polyacrylamide gel electrophoretic patterns of water-soluble myofibrillar proteins demonstrated that all identified myofibrillar proteins except connectin/titin were soluble in water. A part of α-actinin was released from myofibrils by repeated washing with 2.5 mmol/L NaCl and 5 mmol/L L-histidine solution, and subsequent destruction of connectin/titin in washed myofibrils by ultrasonication resulted in solubilization of a large fraction of chicken breast muscle myofibrillar proteins in water. Myofibrillar proteins of chicken leg, pork loin, beef shoulder loin, and lamb were also solubilized in water using this procedure.
  • Takanori Nishimura, Eiko Futami, Jun-Ichi Wakamatsu, Akihito Hattori
    Animal Science Journal 74 5 407 - 416 2003年10月 [査読有り][通常論文]
     
    In order to provide background for understanding biological roles of proteoglycans (PG) in developing skeletal muscle, we have isolated and characterized PG in bovine neonatal skeletal muscle. Two types of PG were isolated from skeletal muscle by density gradient ultracentrifugation and ion-exchange chromatography. One was a small PG (PG-S) with a molecular size of 100-130 kDa, another was a large PG (PG-L) with a molecular size of 300-500 kDa. The glycosaminoglycan chains of PG-S and PG-L were dermatan sulfate and chondroitin sulfate, respectively, judged by cellulose acetate membrane electrophoresis. Immunoblot assays revealed that both PG bound to type I, II, III and IV collagen, laminin and fibronectin. Unlike PG-S, PG-L bound to type V collagen and hyaluronic acid. Small proteoglycans had a core protein of 45 kDa, which reacted with the antibody against the decorin core protein. The N-terminal amino acid sequence of the PG-S core protein was consistent with that of decorin from bovine bone and tendon. Thus, PG-S from neonatal skeletal muscle was identified as decorin in bovines. Immunohistochemical analysis with antibodies against PG-L and PG-S demonstrated that PG-L was located both in the perimysium and endomysium, but PG-S was localized exclusively in the perimysium. These findings suggest that the characterized PG may have distinct roles in the ECM construction of developing skeletal muscle.
  • A Hattori, S Fujimoto, T Nishimura, R Tatsumi, J Wakamatsu, T Ito
    JOURNAL OF MUSCLE FOODS 14 1 1 - 10 2003年03月 [査読有り][通常論文]
     
    Paratropomyosin is a minor myofibrillar protein which in freshly prepared myofibrils is exclusively localized at the A-I junction region of sarcomeres. We investigated the ultrastructural localization of paratropomyosin in intact and postrigor myofibrils by immunoelectron microscopy. Paratropomyosin was localized as two distinct stripes at the A-I junction in intact myofibrils. It also was localized at the position corresponding to the original A-I junction in thick filament-free myofibrils (I-Z-I brushes). However, following postmortem storage, paratropomyosin was found broadly distributed in thin filaments of myofibrils.
  • M Sekikawa, K Shimada, M Fukushima, T Ishikawa, J Wakamatsu, M Mikami
    FOOD CHEMISTRY 69 3 315 - 318 2000年05月 [査読有り][通常論文]
     
    We prepared sarcoplasmic proteins from bovine cardiac muscle immediately after slaughter (1.0 h; 0 days) and from stored muscle at 1, 2 and 7 days post-mortem for SDS-PAGE and Western blotting analysis. Characterization of the ubiquitin antiserum (Sigma, St Louis) showed clear and strong recognition of the ubiquitin band (8.6 kDa) and another minor band (17 kDa) in the purified ubiquitin sample (Sigma, St Louis). Among the sarcoplasmic proteins prepared from stored muscle at 0 and 7 days, this antiserum also reacted with bands corresponding to purified ubiquitin and small amounts of some other, higher-molecular-mass proteins (about 25 and 30 kDa) which were considered to be ubiquitin-protein conjugates. However, the 25 kDa band was faint in the 7 days sample, suggesting that it had degraded. We compared these results with those from oar previous study of bovine skeletal muscles, in which both ubiquitin and the ubiquitin-protein conjugates had almost disappeared in the samples tested at 10 days post mortem. (C) 2000 Elsevier Science Ltd. All rights reserved.
  • 若松 純一, 長尾 哲二, 沼田 正寛, 中村 豊郎, 藤巻 正生
    日本畜産學會報 = The Japanese journal of zootechnical science 68 6 579 - 586 社団法人 日本畜産学会 1997年06月 [査読有り][通常論文]
     
    食肉,特に牛肉は活力•精力の増強のイメージが強いため,疲労の低減や疲労回復といった特有の生体調節機能を有すると期待される.今回我々は,マウスを用いた運動負荷実験において,牛肉が疲労を低減するかどうかについて調査した.いずれの群においても実験期間中の体重の推移に違いはみられなかった.また,飼料摂取量においても,群間で有意差はみられなかった.さらに,一般状態に異常が認められなかったことから,牛肉,牛脂の長期連続摂取は成熟マウスの生育に悪影響を及ぼさないことがわかった.牛肉+牛脂群において,カゼイン+植物油群と比較し,遊泳時間に有意な延長がみられた(p<0.05).カゼイン+牛脂群の遊泳時間にも延長がみられたが,カゼイン+植物油群との有意差は確認されなかった.牛肉+牛脂群およびカゼイン+牛脂群は,懸垂持続試験において強制泳3分後の懸垂持続時間に有意な延長がみられた(p<0.05).強制遊泳30分後では,牛肉+牛脂群のみがカゼイン+植物油群と比較して懸垂持続時間に有意な延長がみられた(p<0.05).これらの結果から,牛肉,特に赤肉部分に抗疲労効果があることが示唆された.カゼインを供試したマウスの血漿中のグルコースおよび乳酸含量は,運動負荷前と比較して大幅に低下したが(p<0.05),牛肉+牛脂を供試したマウスでは負荷前と比べ,血糖はほぼ同等,乳酸については若干の増加がみられた.牛肉+牛脂群におけるこれらの血液成分の変化は,カゼイン+植物油群と比較して小さいものとなった.
  • 若松 純一, 沼田 正寛, 中村 豊郎
    日本食品科学工学会誌 : Nippon shokuhin kagaku kogaku kaishi = Journal of the Japanese Society for Food Science and Technology 44 7 516 - 521 社団法人 日本食品科学工学会 1997年 [査読有り][通常論文]
     
    ''Hanpen''-like whipped sausages with powdered yam as a foaming material were produced and evaluated by an organoleptic test and texture analysis. As the results of using a continuous whipping machine, cohesiveness of the product decreased only about 20%, but hardness, adhesiveness and gumminess decreased 67 similar to 75%. Ten% fat content was most desirable in an organoleptic test. In the experiment, the organoleptically most desirable fat and powdered yam content were 10% and 1%, respectively. Varying the specific gravity by the amount of flowing air of a continuous whipping machine, the specific gravity of the organoleptically most desirable product was 0.6 +/- 0.05. Xanthan gum and/or monoglyceride were added to improve the form stability and emulsification of products. Each evaluations of the added products was higher than a product with no addition.
  • A HATTORI, J WAKAMATSU, T ISHII, K KUWAHARA, R TATSUMI
    BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS 1245 2 201 - 206 1995年10月 [査読有り][通常論文]
     
    Some characteristics of a novel 550-kDa protein which is abundant in skeletal muscle tissues at an early stage of the chick embryo, and localized in the peripheries of adult muscle fibers and at the Z-disks of isolated myofibrils, was investigated, A cosedimentation experiment and solid phase immunoabsorbent assay showed that the 550-kDa protein binds directly to F-actin. Therefore, it is concluded that the 550-kDa protein is a novel actin-binding protein. The 550-kDa protein was also interacted with alpha-actinin, taminin, fibronectin and Type IV collagen, Reactions with several kinds of lectin revealed that the 550-kDa protein is a glycoprotein containing oligosaccharides. Electron microscopic observation of negatively stained 550-kDa protein showed that native 550-kDa protein molecules are particles with an average diameter of 26.5 nm, but those particles treated with ethanol/ether are filamentous structures. These results suggest that the 550-kDa protein in the cytoplasm of unorganized skeletal muscle tissues exists as lipid-protein complex. Consequently, the 550-kDa protein may play an important role in the binding of myofibrils to the basal lamina by interaction with F-actin, cu-actinin, laminin, fibronectin or Type IV collagen.
  • A HATTORI, J WAKAMATSU, T ISHII, K KUWAHARA, R TATSUMI
    BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS 1245 2 191 - 200 1995年10月 [査読有り][通常論文]
     
    We have found a novel protein with a molecular mass of 550 kDa on SDS-polyacrylamide gels, which is abundant in skeletal muscle tissues at an early stage of chick embryonic development. The 550-kDa protein decreased with the progress of development, and only a slight amount of the protein was present in adult chicken skeletal muscle. The 550-kDa protein was purified from the cytoplasm of 18 day embryos by a procedure including ultracentrifugation and gel filtration. The purified 550-kDa protein was essentially free of contaminants as judged by SDS-PAGE. By immunofluorescence and immunoelectron microscopy using the antibody raised against the 550-kDa protein, this protein was shown to be localized in the peripheries of adult muscle fibers and at the Z-disks of isolated myofibrils. These findings have led us to conclude that the 550-kDa protein is a novel myofibrillar protein in chicken skeletal muscle.

MISC

書籍等出版物

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    若松 純一 (担当:分担執筆)
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    若松 純一 (担当:分担執筆範囲:9.2 食肉の構造・品質と加工品)
    講談社 2014年07月 (ISBN: 9784061537392)
  • 齋藤 忠夫, 根岸 晴夫, 八田 一 (担当:分担執筆)
    文永堂出版 2011年 (ISBN: 9784830041211)
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    食肉通信社 2010年 (ISBN: 9784879881137)
  • 日本栄養食糧学会 (担当:分担執筆)
    建帛社 2007年 (ISBN: 9784767961125)
  • 細野 明義, 沖谷 明紘, 吉川 正明, 八田 一 (担当:分担執筆)
    朝倉書店 2007年 (ISBN: 9784254431001)
  • 阿久澤 良造, 坂田 亮一, 島崎 敬一, 服部 昭仁 (担当:共著)
    アイ・ケイコーポレーション 2005年 (ISBN: 4874922236)
  • 細野 明義, 沖谷 明紘, 吉川 正明, 八田 一 (担当:分担執筆)
    朝倉書店 2002年 (ISBN: 4254430795)
  • 太田 明一 (担当:分担執筆)
    シーエムシー 2001年 (ISBN: 488231312X)
  • ハム・ソーセージ図鑑編集委員, 伊藤記念財団 (担当:分担執筆)
    伊藤記念財団 2001年
  • 太田 明一 
    シーエムシー (ISBN: 9784781301969)
  • 太田 明一 
    シーエムシー (ISBN: 4882315386)

講演・口頭発表等

  • 肉のかたさを科学的に考えてみよう!  [招待講演]
    若松 純一
    北海道食文化研究会第7回セミナー 2018年06月 公開講演,セミナー,チュートリアル,講習,講義等
  • 肉を食べたい! 微生物の戦いと葛藤  [招待講演]
    若松 純一
    北海道食文化研究会第4回セミナー 2017年06月 シンポジウム・ワークショップパネル(指名)
  • 体を温める食肉、冷やす食肉  [招待講演]
    若松 純一
    第71回日本栄養・食糧学会大会 シンポジウム「 Meet the World of Meat! ~食肉のおいしさ・機能性・遺伝子制御の新展開~ 」 2017年05月 シンポジウム・ワークショップパネル(指名)
  • 肉の発酵と熟成  [招待講演]
    若松 純一
    第二回「食と健康の達人」拠点シンポジウム北海道の発酵~ワインと食~ 2016年08月 公開講演,セミナー,チュートリアル,講習,講義等
  • 若松純一
    日本畜産学会大会講演要旨 2014年03月
  • 若松純一
    日本栄養・食糧学会関東支部大会シンポジウム講演要旨集 2013年

所属学協会

  • 北海道畜産草地学会   日本栄養・食糧学会   日本食肉科学会   日本畜産学会   Hokkaido Animal Science and Agriculture Society   Japanese Society of Nutrition and Food Science   Japanese Society of Animal Science   

共同研究・競争的資金等の研究課題

  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2022年04月 -2025年03月 
    代表者 : 松浦 友紀子, 若松 純一, 中下 留美子, 亀井 利活
  • 食肉・食肉製品中の亜鉛プロトポルフィリンIX形成におけるフェロケラターぜの作用機序の解明
    公益財団法人 伊藤記念財団:研究助成
    研究期間 : 2023年04月 -2024年03月
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2020年04月 -2023年03月 
    代表者 : 若松 純一
     
    本研究で見出した、好気的条件下でも亜鉛プロトポルフィリンIX(ZnPP )を形成できる乳酸菌(LLC、略称とする)は、これまで改善できなかった表層部を含む発酵ドライソーセージ全体の色調を改善できることを示した。本年度は、実用化に向けた各種要因の調査、並びにLLCによる好気的条件下での形成機構を検討した。 低温での乾燥を行わず高温熟成を行ったドライソーセージでは、LLC添加区では無添加区に比べてZnPP量が増加し、最終製品の断面全体は鮮やかな色調となった。ZnPP量は初めの1週間で最も上昇し、その後はほぼ一定の値となった。同様に、前駆物質であるプロトポルフィリンIX(PPIX)量の上昇も見られた。一方で、低温熟成で製造を行った場合、無添加区とLLC添加区間でZnPP自家蛍光強度および色調に差はなく、乳酸菌による効果は見られなかった。表面のネトや雑菌の増殖を防止する目的で予め低温乾燥を7日間行ったところ、高温熟成を経ても断面全体もしくは外側部分でZnPP形成が促進されなかった。以上より、乳酸菌LLC発酵ドライソーセージにおいてZnPP形成促進による色調改善を行うためには熟成初期の温度と菌の状態が重要であることが示唆された。 LLCの好気的条件下でのZnPP形成機構については、ヘムから脱鉄して亜鉛を挿入するという経路が同じあったことと、肉中の関与する酵素によって阻害されること、嫌気的条件下ではより一層産生することから、LLCは肉中の好気的ではZnPP形成できないプロセスをバイパス的に補うことにより、ZnPPを酸素の影響に関係なくZnPPを産生させることが示唆された。さらに、菌体だけではなく培養した後の培地成分にも形成促進効果が見られ、菌体外に分泌した酵素だけでなく、代謝産物にも形成促進効果がある可能性が示された。
  • 食用ブドウ球菌によるZnPP形成と食肉製品の色調改善効果に関する研究
    公益財団法人 伊藤記念財団:研究助成
    研究期間 : 2022年04月 -2023年03月
  • 乾塩漬ハム中の亜鉛プロトポルフィリンIXの形成様相と存在形態に関する研究(III)
    公益財団法人 伊藤記念財団:研究助成
    研究期間 : 2021年04月 -2022年03月
  • 乾塩漬ハム中の亜鉛プロトポルフィリンIXの形成様相と存在形態に関する研究(II)
    公益財団法人 伊藤記念財団:研究助成
    研究期間 : 2020年04月 -2021年03月
  • 乾塩漬ハム中の亜鉛プロトポルフィリンIXの形成様相と存在形態に関する研究
    公益財団法人 伊藤記念財団:研究助成
    研究期間 : 2019年04月 -2020年03月
  • 食肉タンパク質の抗肥満および脂質代謝促進効果に関する研究(II)
    公益財団法人伊藤記念財団:平成30年度研究助成
    研究期間 : 2018年04月 -2019年03月 
    代表者 : 若松 純一
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 若松 純一
     
    in vivoにおける検討では、鶏肉の人工消化ペプチドでは親水性画分に食後の体温上昇作用があることが示唆された。鶏肉ペプチドの部位間での検討では、部位の影響があることが示された。また、食肉由来の消化・吸収ペプチドは畜種間や部位間でわずかに違いがあることから、生成される微量の特異的なペプチドが効果をもたらしている可能性が示された。一方、肝細胞を用いて人工消化ペプチドをin vitroで評価する系では、これまでのin vivoでの結果と逆の結果が得られたことから、食肉中の消化ペプチドは吸収して直接肝臓に作用して体温上昇をもたらすのではないことが示唆された。
  • 食肉タンパク質の抗肥満および脂質代謝促進効果に関する研究
    公益財団法人伊藤記念財団:平成29年度研究助成
    研究期間 : 2017年04月 -2018年03月 
    代表者 : 若松 純一
  • ZnPP形成能を有する微生物の探索と応用
    伊藤記念財団:平成27年度研究助成
    研究期間 : 2015年06月 -2016年03月 
    代表者 : 若松 純一
  • 国産赤身型牛肉である乳用種牛肉の輸入牛肉に対する差別化技術の開発
    農林水産省:14. 平成25年度農林水産業・食品産業科学技術研究推進事業「実用技術開発ステージ」
    研究期間 : 2013年 -2015年 
    代表者 : 佐々木 啓介
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2012年 -2014年 
    代表者 : 本田 和久, 若松 純一
     
    本研究は、ブロイラーにおいて、食欲増進と肉色改善の両効果を期待できる亜鉛に着目し、これらの効果を最も強力に発揮する亜鉛化合物の選定とその最適給与量の決定を行なうと共に、亜鉛化合物によるブロイラーの食欲増進と肉色改善の両分子機構を解明して、ブロイラーの産肉量増加及び肉質向上の両者を同時に達成しようとするものである。平成25年度は、平成24年度に精製飼料に添加した際に産肉量を増加させ、肉色を有意に改善したペプチド亜鉛を市販飼料に50 ppm添加し、1日齢のブロイラー(チャンキー、雄)に出荷日齢(49日齢)まで給与し、摂食量、体重、種々の臓器・組織(ムネ肉、もも、肝臓、腹腔内脂肪組織)の重量及び肉色に及ぼす影響について調べた。その結果、ペプチド亜鉛の市販飼料への添加は、調べたいずれの項目にも影響を及ぼさなかった。その為、添加量を200 ppmまで段階的に増加させ、3週間給与した際の効果を確認した。その結果、100 ppmのペプチド亜鉛の添加は、肝臓重量および腹腔内脂肪組織重量に影響を及ぼすことなくブロイラーの体重、肝臓、ムネ肉及びももの重量を増加させた。また、ムネ肉の黄色みを上昇させたが、亜鉛プロトポルフィリンIX含量には変化が認められなかった。これらの結果から、ペプチド亜鉛の添加による摂食量、産肉量及び肉色に及ぼす影響は、飼料組成により大きく影響を受けることが示唆された。
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2011年 -2013年 
    代表者 : 若松 純一
     
    肉・食肉製品中のZnPP形成にはpHだけでなく、pHを調節する酸の種類によっても強く影響されることを明らかにし、検証した最適条件でサラミを作ると、発色剤を加えたものと同等の色調を示した。さらに、ZnPP形成を促す微生物の存在も明らかにし、色調改善効果が期待される。さらに、多くの種類の骨格筋でZnPP形成の至適pHを検証したところ、従来のpHよりも低いpHにもあり、遅筋型筋線維の割合と正に相関することが示された。一方、ZnPPの亜鉛補給効果を検証したけれども、残念ながら無機亜鉛と比べて高い効果は認められなかった。
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2008年 -2010年 
    代表者 : 若松 純一, 服部 昭仁, 西邑 隆徳, 服部 昭仁
     
    発色剤無添加食肉製品における亜鉛プロトポルフィリンIX(ZPP)形成機構の解明と、ZPPを利用して食肉製品の色調改善に応用することを目的とした。塩漬食肉製品でZPPが形成されない機構を明らかにした。豚肉での3成分以上がZPP形成に不可欠であること、パルマハム中に形成された水抽出可能なZPPは、ある解糖系酵素と結合していることを明らかにした。レバーを用いて食肉製品の色調改善を試みたところ、ZPPを多量に形成することができ、酸の種類によって非加熱食肉製品における形成能は異なり、色調の望ましい食肉製品の開発につながることが示唆された。
  • Production of additive-free meat products. Investigating into the mechanism leading to good colour dried pork meats without the use of nitrite and nitrate
    Organization for Economic Co-operation and Development (OECD):The Co-operative Research Programme Fellowship Awards for 2009
    研究期間 : 2009年 -2009年 
    代表者 : 若松 純一
  • 食肉タンパク質のS-ニトロシル化と量的変化に及ぼす発色剤の影響について
    財団法人伊藤記念財団:平成19年度研究助成
    研究期間 : 2007年04月 -2008年03月 
    代表者 : 若松 純一
  • 独立行政法人科学技術振興機構:地域イノベーション創出総合支援事業 平成20年度「シーズ発掘試験」A発掘型
    研究期間 : 2008年 -2008年 
    代表者 : 若松 純一
     
    我々はこれまでの研究から、鶏肉や羊肉の摂取により、体温を上昇させることを確認した。そこで本研究では、鶏肉および羊肉による体温上昇機構を明らかにすることと有効成分を特定することを目的とし、動物実験を行って血液生化学検査、各種プロテオーム解析等により検討する。これにより、鶏肉および羊肉の機能を科学的に解明し、「食」を通じた生活の質改善を図るとともに、必要に応じて有効成分を抽出・濃縮し、エネルギー代謝改善のサプリメントの開発につなげる。
  • 発色剤無添加乾塩漬ハムの亜鉛プロトポルフィリンIX(ZPP)形成における海塩の役割について
    財団法人ソルト・サイエンス研究財団:平成18年度研究助成
    研究期間 : 2006年04月 -2007年03月 
    代表者 : 若松 純一
  • 亜鉛プロトポルフィリンIX形成による食肉製品の色調改善法
    ノーステック財団:「研究開発助成事業」若手研究補助金
    研究期間 : 2007年 -2007年 
    代表者 : 若松 純一
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2004年 -2006年 
    代表者 : 若松 純一
     
    我々はこれまでに、亜鉛プロトポルフィリンIX(ZPP)はヘムの鉄と亜鉛に置換によるものではなく、別に形成されたプロトポルフィリンIX(PPIX)に亜鉛を挿入することにより形成されることを明らかにした。パルマハムなどの伝統的乾塩漬食肉製品ではZPPは水で抽出できるが、一般に試薬などのZPPは水に溶解しないことからも、ZPPはミオグロビン(食肉中の主要なヘムタンパク質)以外のものと結合して存在していると考えられる。そこで、パルマハムの水抽出物から硫安分画、イオン交換クロマトグラフィならびに分取用等電点電気泳動により、ZPPを含む画分を精製し、SDS-PAGESより1本の主要なタンパク質のバンドが検出された。MALDI-TOF MSを用いて、このタンパク質は血清アルブミンと同定された。免疫沈降法によりパルマハム水抽出物からアルブミンを精製して、75%アセトン抽出法によりZPPの存在が確認された。一方、水抽出できないZPPが残存していることなどから、ZPPと結合しているタンパク質はアルブミン以外にも存在していると考えられる。亜硝酸塩などの発色剤を添加した食肉製品ではZPPはほとんど見られないことが知られている。この原因を解明するために、モデル実験を用いて検討したところ、亜硝酸塩の酸化作用が原因ではなく、一酸化窒素がZPPならびにその前駆物質であるPPIXの形成を阻害することにより、結...
  • 文部科学省:科学研究費補助金(萌芽研究)
    研究期間 : 2004年 -2005年 
    代表者 : 西邑 隆徳, 服部 昭仁, 若松 純一
     
    家畜のと畜解体工程および食肉加工工程で生じる屑肉などはテーブルミートとしては利用できないが、良質なタンパク質が豊富に含まれており、これらのタンパク質の新たな利活用が求められている。近年、「水」を反応場としてタンパク質などの高分子を分解する亜臨界水・水熱反応が着目されており、本研究では、1.亜臨界水・水熱反応の諸条件(温度、時間)が食肉タンパク質の分解様相に及ぼす影響を明らかにするとともに、2.亜臨界水・水熱反応生成物の生理活性を調べることによって、亜臨界水・水熱反応を食肉タンパク質資源の利活用技術として応用するための基礎的データを得ることを自的とした。先ず、食肉タンパク質に対する適正な亜臨界水・水熱反応条件の概略を把握することを目的に、鶏筋肉、鶏筋原線維、鶏ミオシンおよびコラーゲンを試料として用い、亜臨界水・水熱反応条件がタンパク質分解に及ぼす影響を検討した。その結果、(1)250℃以上の亜臨界水処理では遊離してきたアミノ酸の分解が促進されること、(2)亜臨界水・水熱反応温度の上昇に伴ってアンモニア生成量が増加すること、(3)亜臨界水・水熱反応によって生成されたペプチドの大きさ(分子量)は処理温度の上昇に伴って低下すること、(4)生成されたペプチドのACE阻害活性は鶏ミオシンやコラーゲンでは亜臨界水・水熱反応温度の上昇に伴って顕著に低下した。以上の結果から、食肉タンパク質への...
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2002年 -2004年 
    代表者 : 西邑 隆徳, 森 匡, 服部 昭仁, 若松 純一
     
    活性型ミオスタチンと相互作用する細胞外マトリックス成分を表面プラズモン共鳴法による分子間相互作用解析装置を用いて探索した結果、デコリン、フィブロモデュリン、ヘパラン硫酸プロテオグリカン、ラミニンおよびフィブロネクチンがミオスタチンと亜鉛イオン存在下且つ中性pH域で相互作用することを明らかにした。反応速度論的解析を行った結果、解離定数はデコリン、ヘパラン硫酸プロテオグリカン、ラミニンおよびフィブロネクチンで10^<-8>M、フィブロモデュリンで10^<-10>Mであった。また、デコリンからグリコサミノグリカン鎖を除去したコアタンパク質についてもミオスタチンとの相互作用が認められ、その解離定数、結合速度定数および解離速度定数はグリコサミノグリカン鎖が結合したデコリンとほとんど同じであった。以上の結果から、ミオスタチンはコアタンパク質を介してデコリンと結合していることが示唆された。次に、細胞外マトリックス成分がミオスタチンの筋細胞増殖阻害活性に及ぼす影響についてC2C12筋細胞を用いて検討した。ミオスタチンと相互作用を示した細胞外マトリックス成分をミオスタチンと一緒に亜鉛イオンを含む培地に添加して筋細胞の増殖を調べた結果、いずれの細胞外マトリックス成分を添加してもミオスタチンによる筋細胞増殖阻害作用を抑制することはできなかった。この実験系では、細胞外マトリックス成分は遊離の状態で培...
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2001年 -2003年 
    代表者 : 服部 昭仁, 辰巳 隆一, 西邑 隆徳, 若松 純一
     
    筋原線維タンパク質の水溶化には、筋原線維タンパク質の50%以上を占めるミオシンの溶解が前提となる。本研究では、筋原線維タンパク質の水溶化の機構解明を目的として、ミオシンの低イオン強度下における挙動を追究した。その結果、中性低イオン強度下においてミオシンが溶解することを明らかにし、さらに、ミオシンの中性低イオン強度溶液に対する溶解性の変化とその際のミオシン分子の存在様式と形態変化を追究した。ミオシンの低イオン強度下での溶解にはL-Hisの存在と中性pHであることが重要であり、超音波処理は、必須の工程でなかった。中性低イオン強度溶液への溶解度はL-His濃度に依存して変化した。生理的条件下に戻すと凝集体を形成したため、中性低イオン強度下におけるミオシンの溶解性は可逆的であることを明らかにした。ヒスチジン存在下の中性低イオン強度溶液におけるミオシンは、単量体と微細なフィラメントによるネットワークの二つの形態で存在した。単量体ミオシンは高イオン強度における場合に比べて尾部長が長く、生理的条件や高イオン強度下における性質とは異なる特性を有することを示唆した。従って、この特性がミオシンを低イオン強度溶液に溶解させる要因になっていると結論した。本研究で明らかになったミオシンの特性を利用することにより、食肉製品の品質特性の発現機構解明や新規食肉製品の開発の可能性に明るい展望を認めることができた。

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