INVITRO ECLOSION HORMONE SYNTHESIS AND SECRETION IN THE BRAIN-RETROCEREBRAL COMPLEXES OF THE SILKWORM, BOMBYX-MORI

Brain-retrocerebral complexes of the silkworm, Bombyx mori, were cultured from pre-pupae (1 day after spinning) for 14 days under long-day conditions (16 h light- 8 h dark). The eclosion hormone titres in both brain and endocrine glands gradually increased with age until day 10, falling thereafter by about 75%. Hormonal activity was detected in the media during 11th-14th days. Eclosion hormone titres in the media were similar to those in the haemolymph of intact animals. The molecular weight of the eclosion hormone derived from cultured-brains, retrocerebral complexes and the medium was estimated to be 8000 ± 2000 Da, judged with gel-filtration of a Sephdex-G-75 column chromatography. © 1990.