Pankhurst N W, Hilder P I, Pankhurst P M
School of Aquaculture, University of Tasmania, Launceston, Tasmania, 7250, Australia.
Gen Comp Endocrinol. 1999 Jul;115(1):53-69. doi: 10.1006/gcen.1999.7285.
Gonadal condition and plasma levels of gonadal steroids were measured in relation to behavior in the biparental brood-protecting spiny damselfish Acanthochromis polyacanthus. Fish were captured by SCUBA divers from natural populations on Australia's Great Barrier Reef and immediately bled underwater, following diver or video observation of precapture behaviour. In winter (July), most fish were nonterritorial, with a low proportion of mature males, or vitellogenic females present. In spring (November), most fish were territorial with broods of young at varying stages of maturity, and all stages of gonadal development were represented. Territorial males were larger than nonterritorial fish, but territorial fish that had large (older) young (the end of the brooding phase) had lower condition factors than fish at other stages. Males of all gonad stages had a high proportion of spermatozoa in the testis, but this was higher in November than in July. Ovaries of females commonly had several classes of developing follicles present, although fish that were brooding large young had regressed ovaries with a high incidence of atresia. Plasma levels of testosterone (T) and 11-ketotestosterone were elevated in males of advanced gonadal maturity, and also in relation to recent or imminent spawning behaviour, but there were no changes in plasma 17, 20beta-dihydroxy-4-pregnen-3-one (17,20betaP), which was near assay detection limits at all times. Females had elevated T and 17beta-estradiol (E2) in association with vitellogenesis and elevated T in relation to spawning activity in some fish, but as in males, 17,20betaP levels were low and unchanging. Territorial females without young had lower cortisol levels than nonterritorial fish, or females protecting young. The results confirm the importance of elevated androgens to spawning activity in territorial male fish, but not females where endocrine activity is more closely related to stage of ovarian development. Extended brooding appears to inhibit vitellogenesis, perhaps via a stress-related mechanism.
研究测量了双亲护幼的多棘刺蝶鱼（Acanthochromis polyacanthus）的性腺状况和性腺类固醇的血浆水平，并将其与行为进行关联分析。潜水员在澳大利亚大堡礁的自然种群中用自携式水下呼吸器捕获鱼类，并在潜水员或视频观察到捕获前行为后，立即在水下取血。在冬季（7月），大多数鱼没有领地意识，成熟雄鱼和处于卵黄生成期的雌鱼比例较低。在春季（11月），大多数鱼有领地意识，且幼鱼处于不同成熟阶段，性腺发育的各个阶段均有代表。有领地意识的雄鱼比没有领地意识的鱼体型更大，但有大（年龄较大）幼鱼（育雏阶段末期）的有领地意识的鱼的条件因子低于其他阶段的鱼。所有性腺阶段的雄鱼睾丸中精子比例都很高，但11月的比例高于7月。雌鱼的卵巢通常有几类正在发育的卵泡，不过育有大幼鱼的鱼卵巢退化，闭锁发生率很高。性腺成熟度较高的雄鱼以及与近期或即将发生的产卵行为相关的雄鱼，其血浆睾酮（T）和11-酮睾酮水平升高，但血浆17,20β-二羟基-4-孕烯-3-酮（17,20βP）没有变化，其水平在所有时间都接近检测限。雌鱼在卵黄生成期T和17β-雌二醇（E2）升高，部分鱼在产卵活动时T升高，但与雄鱼一样，17,20βP水平较低且不变。没有幼鱼的有领地意识的雌鱼的皮质醇水平低于没有领地意识的鱼或护幼的雌鱼。结果证实，雄激素升高对有领地意识的雄鱼的产卵活动很重要，但对雌鱼而言并非如此，雌鱼的内分泌活动与卵巢发育阶段关系更为密切。延长育雏似乎会抑制卵黄生成，可能是通过与应激相关的机制。
