Kumar V, Kumar B S
Department of Zoology, Meerut University, India.
Indian J Exp Biol. 1992 Jan;30(1):48-53.
In brahminy myna a photosensitive species, long days caused full gonadal development followed by rapid regression, whereas short days inhibited these responses. Experiments were performed to investigate the effects of duration of photoperiod and gonadal hormones on the recovery of photosensitivity to long photoperiods in male birds. Groups of photorefractory birds were subjected to 8-, 9- or 11-hr daily photoperiods for 45 (6.5 weeks) or 63 (9 weeks) days and then transferred to 15 h daily photoperiods for 60 days to check for the regaining of photoresponsivity. A control group was held under 15L:9D throughout the period of study. Another experiment included three groups of photorefractory males, which were maintained on 9L:15D for 9 weeks and administered with, birth-1day-1 alternately for first 30 days olive oil or different doses (10 or 100 micrograms) of testosterone propionate (TP)/bird/day alternately for first 30 days, and then transferred to 15L:9D for another 30 days to test the recovery of photosensitivity. The results indicated that (i) a period of exposure to short daylengths is required to dissipate photorefractoriness, (ii) termination of photorefractoriness is dependent on the length and duration of photoperiods and (iii) TP inhibits the recovery of photosensitivity in a dose dependent manner.
在家八哥这种对光敏感的物种中，长日照会导致性腺完全发育，随后迅速退化，而短日照则会抑制这些反应。进行了实验以研究光周期时长和性腺激素对雄性鸟类恢复对长光周期的光敏性的影响。将处于光不应期的鸟分组，每天给予8小时、9小时或11小时的光周期，持续45天（6.5周）或63天（9周），然后转移到每天15小时的光周期下持续60天，以检查光反应性的恢复情况。在整个研究期间，一个对照组一直处于15小时光照：9小时黑暗的条件下。另一个实验包括三组处于光不应期的雄性，它们在9小时光照：15小时黑暗的条件下饲养9周，在前30天交替给予橄榄油或不同剂量（10或100微克）的丙酸睾酮（TP）/只/天，然后转移到15小时光照：9小时黑暗的条件下再持续30天，以测试光敏性的恢复情况。结果表明：（i）需要一段短日照暴露期来消除光不应性；（ii）光不应性的终止取决于光周期的长度和持续时间；（iii）TP以剂量依赖的方式抑制光敏性的恢复。
