MOLECULAR MECHANISM OF DIAPAUSE IN INSECT (I) - EXPRESSION OF DIAPAUSE HORMONE GENE AND INCUBATION-TEMPERATURE IN EMBRYONIC STAGE OF BOMBYX-MORI

The embryonic diapause of the silkworm, Bombyx mori, is induced by the diapause hormone (DH) which is secreted from the suboesophageal gangl ion of pupae. The diapause nature of bivoltine strains uses environmen tal stimuli as the initial signal to determine the diapause nature. Th e experiments showed that DH gene expression is a direct response to t he environmental stimulus, such as high incubation temperature. The cD NA from the embryonic stage was cloned and sequence analysis showed th e cDNA encoding DH. Expression patterns of the DH gene in embryonic st age are different at incubation temperatures 15 degrees C and 25 degre es C, suggesting that the incubation temperature as an environmental s ignal is kept within the body to control the DH gene expression at the pupal stage, so that the embryonic diapause of next generation can be determined.