Molecular analysis of diapause and stress resistance during development of artemia embryos

卤虫（Artemia franciscana）通过成囊和进入滞育来承受恶劣的环境，滞育是一种胚胎发育被阻止和代谢活动大大降低的生理状态。被包囊的胚胎具有极强的抗应激能力，即使在环境温度下水合，它们也能在高温、干燥和无氧条件下存活数年。卤虫滞育发生在特定的生活史阶段，而不是像许多其他动物那样对环境条件本身作出反应。在包囊形成过程中，卤虫胚胎表现出差异基因表达，产生诱导和维持滞育所需的蛋白质，如调节细胞生长和分化的蛋白质，滞育特异性胚胎结构组装所需的蛋白质，以及在暴露于压力期间保护细胞的分子伴侣。这项工作的长期目标是阐明卤虫胚胎调节包囊和滞育的细胞、分子和生化机制，并确定胚胎如何在生理胁迫下生存。短期目标包括识别卤虫胚胎成囊过程中调控的基因，并确定其产物的功能。特别令人感兴趣的是分子伴侣，如小的热休克蛋白和artemin，这两个丰富的蛋白质在成囊的卤虫胚胎。 这项工作有可能揭示卤虫和其他生物体（如昆虫）滞育的重要蛋白质功能，后者在农业中具有重要意义。感兴趣的蛋白质的例子包括那些介导细胞内信号传导途径，影响代谢活动，细胞生长，基因转录和衰老，所有的理解细胞的根本重要性。分子伴侣在维持细胞在压力和正常生长过程中的作用也将被检查。这些结果将有助于我们了解真核细胞在发育过程中和暴露于压力下的基本过程。此外，所获得的信息将在医学、农业、林业和水产养殖业中具有潜在的应用。

The brine shrimp, Artemia franciscana, withstands harsh environments by encysting and entering diapause, a physiological state where embryo development is arrested and metabolic activity is greatly reduced. The encysted embryos are extremely stress resistant and they survive high temperature, desiccation and years without oxygen even when hydrated at ambient temperature. Artemia diapause occurs at specific life history stages and not in response to environmental conditions per se, as occurs in many other animals. During encystment, Artemia embryos exhibit differential gene expression yielding proteins required for induction and maintenance of diapause such as those regulating cell growth and differentiation, others needed for assembly of diapause-specific embryo structures, and molecular chaperones that protect cells during exposure to stress. The long term objectives of the work are to elucidate cell, molecular and biochemical mechanisms by which Artemia embryos regulate encystment and diapause and to determine how embryos survive physiological stress. Short term objectives include the identification of genes regulated during Artemia embryo encystment and determining the functions of their products. Of particular interest are molecular chaperones such as the small heat shock proteins and artemin, both abundant proteins in encysted Artemia embryos.  The work has the potential to reveal protein functions important to diapause in Artemia and other organissms such as insects, the latter of significance in agriculture. Examples of interesting proteins include those mediating intracellular signalling pathways which influence metabolic activity, cell growth, gene transcription and aging, all of fundamental importance in understanding cells. The role of molecular chaperones in maintaining cells under stress and during normal growth will also be examined. The results will contribute to our appreciation of fundamental processes in eukaryotic cells during development and upon exposure to stress. Moreover, the information obtained will have potential applications in medicine, agriculture, forestry and aquaculture.