Abstract
The developing ovary from the pharate adults of the silkworm, Bombyx mori was incubated in vitro with the modified Wyatt's modium, and the effects of diapause hormone on trehalase activity were surveyed in this system. Trehalase activity began to increase in 3 hr and reached the maximum level at 12 hr after incubation with the hormone (DH-B). The dose response experiments showed that trehalase activity rose linearly against the logarithmic increase of DH-B doses from 0.5 μg/ml and a half-maximum effect of the hormone was found at 6×10-7 M. Addition of adenosine 3', 5'-cyclic monophosphate and guanosine 3', 5'-cyclic monophosphate into the incubation medium did not cause any enhancement of trehalase activity. These suggest that the activation of trehalase in developing ovaries by the diapause hormone is direct but such stimulation of the enzyme is not simply mediated by cyclic nucleotides.
