Paitz Ryan Thomas, Mommer Brett Christian, Suhr Elissa, Bell Alison Marie
School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois.
School of Biological Sciences, Illinois State University, Normal, Illinois.
J Exp Zool A Ecol Genet Physiol. 2015 Aug;323(7):422-9. doi: 10.1002/jez.1937. Epub 2015 Jun 2.
Embryonic exposure to steroids often leads to long-term phenotypic effects. It has been hypothesized that mothers may be able to create a steroid environment that adjusts the phenotypes of offspring to current environmental conditions. Complicating this hypothesis is the potential for developing embryos to modulate their early endocrine environment. This study utilized the threespined stickleback (Gasterosteus aculeatus) to characterize the early endocrine environment within eggs by measuring four steroids (progesterone, testosterone, estradiol, and cortisol) of maternal origin. We then examined how the concentrations of these four steroids changed over the first 12 days post fertilization (dpf). Progesterone, testosterone, estradiol, and cortisol of maternal origin could be detected within unfertilized eggs and levels of all four steroids declined in the first 3 days following fertilization. While levels of progesterone, testosterone, and estradiol remained low after the initial decline, levels of cortisol rose again by 8 dpf. These results demonstrate that G. aculeatus embryos begin development in the presence of a number of maternal steroids but levels begin to change quickly following fertilization. This suggests that embryonic processes change the early endocrine environment and hence influence the ability of maternal steroids to affect development. With these findings, G. aculeatus becomes an intriguing system in which to study how selection may act on both maternal and embryonic processes to shape the evolutionary consequence of steroid-mediated maternal effects.
胚胎期接触类固醇通常会导致长期的表型效应。据推测，母亲可能能够创造一种类固醇环境，使后代的表型适应当前的环境条件。使这一假设变得复杂的是，发育中的胚胎有可能调节其早期内分泌环境。本研究利用三刺鱼（Gasterosteus aculeatus），通过测量四种源自母体的类固醇（孕酮、睾酮、雌二醇和皮质醇）来表征卵内的早期内分泌环境。然后，我们研究了这四种类固醇在受精后前12天（dpf）内的浓度变化情况。在未受精卵中可以检测到源自母体的孕酮、睾酮、雌二醇和皮质醇，并且在受精后的前3天，所有这四种类固醇的水平均下降。虽然在最初下降之后，孕酮、睾酮和雌二醇的水平仍然较低，但皮质醇的水平在8 dpf时再次上升。这些结果表明，三刺鱼胚胎在存在多种母体类固醇的情况下开始发育，但受精后水平开始迅速变化。这表明胚胎过程会改变早期内分泌环境，从而影响母体类固醇影响发育的能力。基于这些发现，三刺鱼成为一个有趣的系统，可用于研究选择如何作用于母体和胚胎过程，以塑造类固醇介导的母体效应的进化后果。
