Extensive Intracellular Translocations of a Major Protein Accompany Anoxia in Embryos of Artemia franciscana

Abstract

Cells of encysted gastrula embryos of the crustacean Artemia franciscana exhibit extraordinary stability during prolonged anoxia. We find that they contain an abundant protein (referred to as "26-kDa protein") that undergoes translocation to the nucleus during anoxia. The reverse translocation rapidly occurs when anoxic embryos are returned to aerobic conditions. A similar translocation appears to take place in embryos exposed to 42°C aerobic heat shock and prolonged exposure to low temperature (0-2°C), and in diapause embryos. Gel filtration and Western immunoblotting indicate that the 26-kDa protein is translocated to other cellular compartments and may also be associated with a wide variety of "soluble" proteins during anoxia. This protein makes up roughly 15% of the total nonyolk embryo protein and is, by far, most abundant in the encysted embryo stage of the life cycle. The hypothesis is advanced that the 26-kDa protein may play the role of a metabolic regulator and/or a protective molecular chaperone during prolonged anoxia and other forms of stress.