Heat Shock Gene Expression: An Indicator of Thermal Stress in Marine Animals

对基因表达的环境调控对海洋生物的生存和成功肯定是至关重要的。然而，目前对海洋真核生物中温度等环境因素与基因转录调控之间的相互作用知之甚少。环境控制基因表达的唯一众所周知的例子是热休克蛋白(HSPs)，它是由高温和其他应激(例如，缺氧)诱导的，到目前为止所有研究的生物体中都有HSPs。然而，很少有海洋物种被研究过。本项目将研究几种不同热适应的海洋动物的热休克基因(HSP)系统，以确定：(I)在不同适应的物种(或种群)中发生热应激(HSP诱导)的阈值温度，(Ii)沿海鱼类幼体和成体的HSP诱导模式，以及(Iii)HSP表达的种间(或种群间)差异的潜在分子基础。将特别注意居住在不同热区的同属物种，例如纬度分离的两属鱼类--梭鱼和贻贝--贻贝，以及其幼体阶段生活在可能温暖的海湾和河口的各种鱼类。这些研究的目标包括：(I)开发一个强大的分子指数来衡量环境胁迫；(Ii)发现热耐受的基本机制；以及(Iii)阐明HSP调节机制中的进化差异，这些机制决定了不同适应物种诱导温度的差异。热休克诱导温度可能为了解不同物种和种群的耐热性，即了解生物地理分布模式的基本分子基础提供重要的见解。开发一种相对简单的无脊椎动物热休克蛋白筛选方法，可以为测量自然海洋生物种群经历的应激水平提供有用的方法。

Environmental regulation of gene expression is certain to be critical for the survival and success of marine organisms. At present, however, very little is known about the interactions between environmental factors, e.g., temperature, and the regulation of transcription of genes in any marine eucaryotic organism. The only well understood example of environmental control of gene expression is in the case of the heat shock proteins (HSPs), which are induced by high temperature and other stresses (e.g., anoxia) in all organisms so far studied. However, few marine species have been examined. This project will examine the heat shock gene (HSP) system in several species of differently thermally-adapted marine animals to determine: (i) the threshold temperatures at which heat stress (HSP induction) takes place in differently adapted species (or populations), (ii) the induction patterns of HSPs in larval and adult individuals of coastal fishes, and (iii) the underlying molecular bases of the inter-specific (or inter-population) differences in HSP expression. Particular attention will be given to congeneric species inhabiting different thermal regimes, e.g., latitudinally separated species of two genera of fish, Sebastes and Embiotoca, the mussel Mytilus, and to various fishes whose larval stages inhabit potentially warm bays and estuaries. The goals of these studies include (i) the development of a powerful molecular index for gauging environmental stress; (ii) the discovery of basic mechanisms of thermal tolerance, and (iii) the elucidation of evolutionary differences in the HSP regulatory mechanisms, which set the differences in induction temperatures in differently- adapted species. HSP induction temperatures may provide important insights into the thermal tolerance of different species and populations, i.e., into the fundamental molecular basis for biogeographical distribution patterns. The development of a relatively simple screening method for HSP in invertebrates, could provide a useful method for gauging the level of stress experienced by natural populations of marine organisms.