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

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.