ACCUMULATION OF 3-HYDROXYKYNURENINE IN OVARIAN FOLLICLES IN RELATION TO DIAPAUSE IN THE SILKWORM, BOMBYX MORI L.*

Investigations were undertaken to elucidate the mechanism of the accumulation of 3-hydroxykynurenine (3-OHK) in pupal ovarian follicles of the silkworm, Bombyx mori L. In diapause-egg-producer pupa (D-pupa), 3-OHK is actively transferred into and accumulated in the follicles from hemolymph, whereas no such phenomenon is observed in non-diapause-egg-producer pupa (ND-pupa). In D-pupa, the following facts indicate that an active transport is one of the major factors involved in the accumulation of 3-OHK; namely 3-OHK accumulation in follicles exceeds that of hemolymph by about 18-fold and the transport is inhibited by DNP and sodium azide. Autoradiography revealed that accumulated 3-OHK localized specifically on the surface of the yolk spheres of the oocytes. On the other hand, in ND-pupa, 3-OHK is considered to be transferred into the follicles by a simple diffusion, since 3-OHK concentration in a follicle nearly coincides with that of hemolymph. The accumulation of 3-OHK could be arrested by the removal of suboesophageal ganglion (Sg) in D-pupa. These results are discussed in relation to the action of the “diapause factor” released from Sg.