Institute for Applied Ecology, University of Canberra, Canberra, Australia.
Australian National Wildlife Collection, CSIRO, Canberra, Australia.
J Exp Zool A Ecol Integr Physiol. 2021 Mar;335(3):301-310. doi: 10.1002/jez.2441. Epub 2021 Jan 7.
Environmental sex determination (ESD) is common among ectothermic vertebrates. The stress axis and production of stress hormones (corticosteroids) regulates ESD in fish, but evidence of a similar influence in reptiles is sparse and conflicting. The central bearded dragon (Pogona vitticeps) has a system of sex determination involving the interplay between sex chromosomes (ZZ/ZW female heterogamety) and the thermal environment. High egg incubation temperatures induce sex reversal of the ZZ genotype, feminizing chromosomally male individuals. Here we show that corticosterone elevation is not associated with sex reversal in the central bearded dragon, either during embryonic development or adulthood. We also demonstrate experimentally that sex determination is not affected by corticosterone injection into the yolk. This strongly suggests that stress axis upregulation by high temperature during incubation does not cause sex reversal in P. vitticeps. Our work is in general agreement with other research in reptiles, which suggests that the stress axis does not mediate sex in reptiles with ESD. Alternative biological systems may be responsible for capturing environmental conditions during reptile development, such as cellular calcium and redox regulation or the action of temperature-sensitive splicing factors.
环境性别决定（ESD）在变温脊椎动物中很常见。应激轴和应激激素（皮质类固醇）的产生调节鱼类的 ESD，但在爬行动物中类似影响的证据很少且相互矛盾。中央鬃狮蜥（Pogona vitticeps）有一种性别决定系统，涉及性染色体（ZZ/ZW 雌性异型性）和热环境之间的相互作用。高卵孵化温度诱导 ZZ 基因型的性别反转，使染色体雄性个体雌性化。在这里，我们表明，无论是在胚胎发育还是成年期，皮质酮的升高都与中央鬃狮蜥的性别反转无关。我们还通过实验证明，向蛋黄中注射皮质酮不会影响性别决定。这强烈表明，孵化过程中高温引起的应激轴上调不会导致 P. vitticeps 的性别反转。我们的工作与其他爬行动物的研究基本一致，这表明应激轴不能介导具有 ESD 的爬行动物的性别。替代的生物系统可能负责在爬行动物发育过程中捕获环境条件，例如细胞钙和氧化还原调节或温度敏感剪接因子的作用。
