Effect of a light pulse during the dark on photoperiodic regulation of the rate of thyroxine-induced, spontaneous, and prolactin-inhibited metamorphosis in Rana pipiens tadpoles.

摘要: Since Rana pipiens tadpoles injected with thyroxine (T4) early in the dark develop more slowly than those light, we studied effect of giving a light pulse 1 hr dark. Tadpoles under 7.5-W red bulb darkened room 0.2 microgram T4 daily at 2200 went through metamorphosis faster on 12L:3D:1L:8D cycle after injection 12L:12D without pulse, and even 12L:1.5D:1L:9.5D before injection. Thus 1-hr counteracted metamorphic delay resulting from administration dark, set motion conditions that resulted rapid response to an T4. However, had no growth development older or younger untreated constantly immersed 30 micrograms/liter Larvae 21L:3D 0700 just start main phase progressed only pulse. length immediately was significant. There difference cycles effectiveness injections 10 micrograms prolactin (PRL) promoting tail antagonizing resorption induced by immersion. Under these conditions, PRL utilization did not appear be inhibited