Adaptive significance of a small heat shock/alpha-crystallin protein (p26)in encysted embryos of the brine shrimp, Artemia franciscana

Encysted embryos of the primitive crustacean, Artemia franciscana, are amon g the most resistant of all animal life history stages to extremes of envir onmental stress. This resistance has likely been acquired during evolutiona ry adaptation to their harsh ecological setting, In the laboratory, for exa mple, some of these embryos survive more than 6 years of continuous anoxia while fully hydrated and at room temperature, a phenomenal capability that can easily be related to their frequent encounters with anoxic conditions i n nature. A small heat shock protein belonging to the alpha-crystallin fami ly of proteins, referred to as p26, appears to play a central role in the s tress resistance of these embryos. Our evidence shows that this protein is an important component in their adaptive repertoire, and vital for the surv ival of Artemia in nature.