Abstract
First, we confirmed that a trehalase specific inhibitor, validoxylamine A, injected into diapause-egg producing pupae produced significant numbers of nondiapause eggs, suggesting that biosynthesis of diapause hormone and/or its release into the hemolymph may be reduced by inhibition of trehalase activity in brain-subesophageal ganglion (SG). Next, to better understand trehalose catabolic activities in brain-SG of diapause- and nondiapause-egg producers of the silkworm, Bombyx mori, we examined the expression of trehalase-1 and -2 mRNAs during pupal-adult development. These mRNAs code for soluble and integral-membrane proteins, respectively. Remarkable differences in the mRNA amounts were not found in either the diapause- and nondiapause-egg producers, but the expression of these mRNAs increased much more rapidly prior to adult emergence, as compared with dopa decarboxylase mRNA, a key enzyme in the formation of the neurotransmitter dopamine. These results suggest involvement of trehalases within brain-SG in adult ecdysis.
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