Schwabl H
Rockefeller University, Field Research Center for Ecology and Ethology, Millbrook, New York 12545, USA.
J Exp Zool. 1996 Oct 1;276(2):157-63. doi: 10.1002/(SICI)1097-010X(19961001)276:2<157::AID-JEZ9>3.0.CO;2-N.
Past studies have shown that the yolk of the canary (Serinus canaria) egg contains maternal testosterone, that its concentrations increase in the subsequently formed eggs of a clutch, and that testosterone influences development. The present study investigated 1) if the testosterone levels vary in the female during yolk formation; 2) how such putative variations may be related to the concentrations of maternal testosterone in the yolk; and 3) if environmental factors, such as day length, can modify the testosterone levels in the mother and her eggs. Maternal testosterone levels, measured in the females' feces, increased during yolk formation and egg laying, and decreased during incubation. This pattern was modified by day length. In a photoperiod of 12 h of light and 12 h of darkness (12L 12D), female testosterone levels decreased after the last egg of the clutch was laid while in a photoperiod of 16L 8D, they decreased after the first egg was laid. These different patterns were reflected in the testosterone concentrations in the egg yolk. Further, the eggs of subsequent clutches that were produced under a naturally changing photoperiod differed significantly in their testosterone concentrations. Finally, the doses of testosterone in the yolk of individual eggs were positively correlated with the concentrations of testosterone in the female during the yolk phase of each egg. I conclude that here we have a mechanism which communicates environmental conditions from the mother to the offspring, and that this mechanism serves to optimize reproduction and/or modify offspring traits.
过去的研究表明，金丝雀（Serinus canaria）卵的卵黄中含有母体睾酮，其浓度在一窝随后形成的卵中会增加，且睾酮会影响发育。本研究调查了：1）在卵黄形成过程中雌性体内的睾酮水平是否会发生变化；2）这种假定的变化可能如何与卵黄中母体睾酮的浓度相关；3）诸如日照长度等环境因素是否会改变母体及其卵中的睾酮水平。通过测量雌性粪便中的母体睾酮水平发现，在卵黄形成和产卵期间其水平升高，而在孵化期间降低。这种模式受日照长度的影响。在12小时光照和12小时黑暗（12L 12D）的光周期中，雌性睾酮水平在一窝中的最后一枚卵产下后下降，而在16L 8D的光周期中，它们在第一枚卵产下后下降。这些不同模式反映在卵黄中的睾酮浓度上。此外，在自然变化的光周期下产生的后续窝卵在睾酮浓度上有显著差异。最后，单个卵的卵黄中睾酮剂量与每个卵的卵黄形成阶段雌性体内的睾酮浓度呈正相关。我得出结论，我们在此发现了一种将环境条件从母体传递给后代的机制，并且这种机制有助于优化繁殖和/或改变后代性状。
