Expression profile of arylphorin gene during diapause and cold acclimation in the rice stem bore 4 ( ] IItilo sirppressatis VValker ( Lepidoptera : Cr mbidae )

A storage protein gene, CsSP2, was eloned and sequenced from the rice stem borer, Chilo st4npi'essalis. Analysis of the cDNA scquence revealed an open reading frame of2,118bp in length which encodcs an arylphorin-like protein with a calculated molccular weight of 83.7 kDa. The cxpression level of CsSP2 was higher in non-diapausing Iarvae than in diapausing larvae at 20"C. When diapausing larvae wcrc acclimatized in a stepwise fashion from 200C to 5eC, CsSP2 expression was up-regulated five days after acclimation at 1SOC. The ]evel was maintained for 10 days after acclimation at 5aC and down-regulated thereafter. Somc up-regulation in CsSP2 expression was detectcd in the postdiapause state. In non-diapausing larvae, (]sSP2 expressien was down-regulated in the course of cold accliniation. Protein products of CsSP2 might have an important role as an amino acid reservoir or a cellular defense mechanism during diapatTse, Key }vords: Arylphorin; cold acclimation; diapausc; hexamerin; rice stcm borer