Studies on the quality changes of Japanese oyster during transportation

日本牡蛎是日本最重要的经济贝类之一。牡蛎经常作为活牡蛎运输，并暴露在不利的环境变化中，包括缺氧和中暑。在正常和应激条件下，包括HSP70家族在内的应激蛋白可能对牡蛎具有重要作用。为了初步了解应激蛋白在牡蛎中的作用，作者决定克隆HSP70家族的cDNA。因此，从日本牡蛎的cDNA文库中分离到了HSP70家族成员--热休克相关蛋白(HSC71)、热诱导热休克蛋白(HSP70)和葡萄糖调节蛋白(GRP78)的全长cDNAs。Northern印迹分析表明，HSC71在热休克处理前后的牡蛎组织中均有结构性表达。相反，热休克处理可显著诱导HSP70和GRP78mRNAs的表达，而正常组织中HSP70和GRP78mRNAs的表达水平很低。作者还利用双向电泳检测了暴露于空气中的牡蛎组织中诱导和/或减少的蛋白质。其中一些蛋白质是通过N末端或内部的氨基酸序列来鉴定的。作者发现了一种迄今未见报道的新蛋白质，并将其命名为Ogu1。从牡蛎cDNA文库中克隆了Ogu1基因的全长编码区。Ogu1全长38 kDa，含342个氨基酸残基。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.