Studies on the quality changes of Japanese oyster during transportation

日本牡蛎是日本经济上最重要的贝类之一。牡蛎通常作为活牡蛎运输，并暴露在缺氧和热休克等不利环境变化中。包括HSP70家族在内的应激蛋白可能在正常和应激条件下对牡蛎起重要作用。为了初步弄清应激蛋白在牡蛎中的作用，作者决定克隆HSP70家族的cdna。结果，从日本牡蛎cDNA文库中分离出热休克同源蛋白（HSC71）、热诱导热休克蛋白（HSP70）和葡萄糖调节蛋白（GRP78）的全长cDNA。Northern blot分析显示，HSC71在热休克处理或不热休克处理的牡蛎组织中均有组成性表达。相反，热休克处理显著诱导了HSP70和GRP78 mrna的表达，而正常组织中这些mrna的表达水平很低。作者还利用二维电泳技术检测了牡蛎组织在空气暴露贮藏过程中的诱导蛋白和/或还原蛋白。其中一些蛋白质是通过这些n端或内部部分的氨基酸序列来鉴定的。作者发现了一种迄今未被报道的新蛋白，并将其命名为Ogu1。从牡蛎cDNA文库中分离到编码Ogu1的全长cDNA。Ogu1含有342个氨基酸残基，分子量为38kDa。Ogu1的等电点为6.7。

Japanese oyster is one of the most economically important shellfish in Japan. The oyster is often transported as live one and exposed to adverse environmental changes including hypoxia and heatshock. Stress proteins including HSP70 family may have important roles for the oyster under normal and stress conditions. As a preliminary to resolve the role of stress proteins in the oysters, the author decided to clone the cDNAs of HSP70 family. As a result, full-length cDNAs for a constitutively expressed heat-shock-cognate protein (HSC71), a heat-inducible heat shock protein (HSP70) and a glucose-regulated protein (GRP78), members of the HSP70 family, were isolated from a Japanese oyster cDNA library. Northern blot analysis showed that HSC71 was expressed constitutively in oyster tissues with or without heat shock treatment. On the contrary, HSP70 and GRP78 mRNAs were induced remarkably with heatshock treatment, while those expression levels were very low in the normal tissues.The author also detected the induced and/or reduced proteins in the oyster tissues during the air-exposed storage using the two dimensional electrophoresis. Some of those proteins were identified by the amino acid sequences of those N-terminal ends or inner parts. The author found a new protein that has not been reported so far, and named it as Ogu1. Full-length cDNA encoding oyster Ogu1 was isolated from oyster cDNA library. Ogu1 contains 342 amino acid residues and is 38kDa. The isoelectric point of Ogu1 is 6.7.