Diapause regulation and stress tolerance in artemia embryos: gene expression, protein function and metabolism

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Embryos of the crustacean, Artemia franciscana, may develop into swimming larvae or they may encyst and enter diapause, a physiological state characterized by developmental arrest and greatly reduced metabolic activity. Encysted embryos are extremely stress tolerant and they survive high temperature, desiccation and years of anoxia even when hydrated at ambient temperature. As such, encysted Artemia embryos represent one of the most stress resistant metazoan life forms on earth. Artemia embryos exhibit differential gene expression during diapause-destined development which yields proteins required for initiation. maintenance and perhaps termination of diapause. The long term objectives of the work are to elucidate cell, molecular and biochemical mechanisms by which Artemia embryos regulate diapause-specific development and to determine how embryos survive physiological stress. Short term objectives include the identification of genes that are up-regulated during diapause and determining the functions of their protein projects. Of particular interest are abundant molecular chaperones such as the diapause-specific small heat shock proteins and the ferritin homologue artemin. Other examples of interesting proteins include those mediating intracellular signalling pathways which influence metabolic activity, cell growth and division, and gene transcription. Protein changes that regulate diapause termination, a field that is almost untouched, will also be identified. The results will contribute to our apreciation of fundamental processes in eukaryotic cells during development and upon exposure to stress. The information obtained will have potential applications in medicine as perturbation of small heat shock protein function leads to disease. Additionally, many insects that undergo diapause influence agriculture and forestry through their roles as pests and Artemia has an important role as a source of feed in aquaculture.