INFLUENCES OF SEX, CASTRATION, AND ANDROGENS ON THE EUMELANIN AND PHEOMELANIN CONTENTS OF DIFFERENT FEATHERS IN WILD MALLARDS
INFLUENCES OF SEX, CASTRATION, AND ANDROGENS ON THE EUMELANIN AND PHEOMELANIN CONTENTS OF DIFFERENT FEATHERS IN WILD MALLARDS
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DOI：
10.1111/j.1600-0749.1995.tb00658.x
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发表时间：
1995-06-01
期刊：
影响因子：
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通讯作者：
WAKAMATSU, K
中科院分区：
文献类型：
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作者：
HAASE, E;ITO, S;WAKAMATSU, K
在野鸭中，公鸭鲜艳的婚礼羽毛代表了中性的、不依赖性激素的颜色，这种颜色在去势后两性最终都会表现出来。我们比较了5组夏季婚后蜕皮的绿头鸭，完整的母鸡，完整的公鸭，阉割的公鸭，春季注射睾酮的阉割公鸭和春季注射5 α -二氢睾酮的阉割公鸭，头部、胸部、腹部和尾下的羽毛中黑素和真黑素的含量。在头羽和尾下羽中，原鸟的性腺激素和阉割后的睾酮注射显著降低了真黑素的含量，并有增加现象黑素含量的趋势，从而使未处理的阉割鸟的黑色素类型由真黑素变为混合黑素。各组间羽羽真黑素含量无显著差异，但该部位的现象黑素含量在未注射睾丸激素的实验组和未注射睾丸激素的实验组均显著升高。再一次，黑色素类型从去势组的黑色素变为其他三组的混合黑色素。阉割后的母鸡、未阉割的公鸭和注射睾酮的阉割后的公鸭，其胸毛中高黑色素含量显著降低，同时真黑色素含量有升高的趋势。在这个部位，发生了从泛黑到混合黑的变化。α -二氢睾酮对去势鱼黑色素含量的影响远低于睾酮，且呈中等颜色。这两种雄激素的不同作用可能是它们向雌激素转化的不同造成的。
In mallards the bright nuptial plumage of the drake represents the neutral, sex hormone-independent coloration of the species that both sexes eventually exhibit after castration. We compared the pheo- and eumelanin contents of feathers from the head, breast, flank, and under-tail coverts in five groups of mallards after the post-nuptial molt in summer: intact hens, intact drakes, castrated drakes, castrated drakes injected with testosterone during the spring, and castrated drakes injected with 5 alpha-dihydrotestosterone during the spring. In the head feathers and under-tail coverts, the gonadal hormones of the intact birds and the testosterone injections into castrates significantly reduced the eumelanin content, tended to increase the pheomelanin content, and, thereby, changed the melanin type from eumelanic in the untreated castrates to mixed melanic in the other three groups. The eumelanin contents of the flank feathers did not differ among the groups, but the pheomelanin contents at this site was significantly elevated in the two intact groups and the testosterone-treated compared to the uninjected castrates. Again, the melanin type changed from eumelanic in the castrates to mixed melanic in the other three groups. The high pheomelanin content of the breast feathers in the castrated birds was significantly reduced in the hens, intact drakes, and testosterone-injected castrates with a concomitant tendency for elevated eumelanin contents. At this site, a change occurred from pheomelanic to mixed melanic. 5 alpha-dihydrotestosterone was dearly less effective than testosterone in affecting the melanin contents in castrates and resulted in an intermediate coloration. The differing effects of the two androgens might be a result of differences in their conversion to estrogens.