Title Physiological function of the insulin-related peptides in molluscs
Authers Masahiko AWAJI and Shunsuke MORIYAMA
Keywords insulin, Lymnaea, Aplysia, Crassostrea , Mollusca
Citation Bull. Fish. Res. Agen. No.26, 77-82, 2008
Peptides structurally related to vertebrate insulin have been identified in invertebrates including mollusks. In the pond snail, Lymnaea stagnalis , clusters of neurons called light green cells in the cerebral ganglia produce and release molluscan insulin-related peptides (MIPs) which are suggested to stimulate the use of hemolymph glucose as an energy source by growing tissues. In the sea hare, Aplysia californica , Aplysia insulin (AI) is produced in the central region of the cerebral ganglia. The expression of AI mRNA decreases when the animal is deprived of food, and injections of AI reduce hemolymph glucose levels. These results suggest that the gastropod insulin-related peptides play important roles in growth control and carbohydrate homeostasis. In bivalves, the structure and gene expression of the insulin-related peptide are detailed only in the Pacific oyster, Crassostrea gigas . The expression of the oyster insulin-related peptide (oIRP) mRNA increases in March prior to growth and germ cell development, and decreases in July after active spawning. To gain insight into the physiological function of oIRP, changes in the oIRP mRNA levels under food deprivation or glucose administration were examined, but significant changes in the gene expression were not detected.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull26/awaji.pdf