title: Prothoracicotropic hormone activity in the embryonic brain of the tobacco hornworm, Manduca sexta.
abstract: Head segments and brains were extirpated from embryos of the tobacco hornworm, Manduca sexta, extracted and the resulting extracts assayed for prothoracicotropic hormone (PTTH) activity on prothoracic glands from day 3 fifth instar larvae and day 0 pupae. Dose-response curves were generated and indicated the presence of PTTH activity in embryonic brains and head segments, suggesting a role(s) for this neurohormone during embryogenesis. Maximal PTTH activity was found in brains from embryos 117 h post-oviposition, just prior to hatching, but activity was also noted in head segments as early as 24 h post-oviposition. These data on PTTH and those on ecdysteroids and juvenile hormones in embryos suggest that these 3 classes of hormones which control insect post-embryonic development, may also be involved in the regulation of developmental processes in the embryo.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D007301:Insect Hormones / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D007313:Insecta / Q000378:metabolism*; D007814:Larva / Q000378:metabolism
chemical_list: D007301:Insect Hormones; C009089:prothoracicotropic hormone