Diapause and Anhydrobiosis in Embryos of Artemia franciscana : Metabolic Depression, LEA Proteins and Water Stress(Papers presented at the Seminar, "NIAS International Seminar for Cryobiology and Cryotechnology")

Abstract

Metabolic depression is typically correlated with extended survival of environmental challenge and energy-limitation in early life stages of various invertebrates and vertebrates. Diapause is an ontogenetically-programmed reduction of development and often metabolism seen in many invertebrates. When embryos of Artemia franciscana enter the state of diapause, the overall metabolic depression is estimated to be greater than 99%. These embryos also contain trehalose and express multiple isoforms of Late Embryogenesis Abundant (LEA) proteins, constituents often present in a number of such anhydrobiotic animals. The mRNA levels for LEA proteins are highest in diapause and post-diapause embryos that possess desiccation tolerance, but are very low in desiccation-intolerant nauplius larvae. Stable transfection of human HepG2 cells with AfrLEA2 and AfrLEA3m was performed to evaluate the possibility of improved survivorship during drying. A trehalose transporter was used for intracellular loading of this disaccharide. LEA proteins improved desiccation tolerance in mammalian cells during acute drying and immediate rehydration.