Winnicki S K, Hauber M E, Paitz R T, Schelsky W M, Benson T J
Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Program in Ecology, Evolution, and Conservation, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
J Exp Zool A Ecol Integr Physiol. 2025 Nov;343(9):1103-1116. doi: 10.1002/jez.70024. Epub 2025 Aug 8.
Vertebrate growth rates may respond to maternally supplied steroids, yet injections of individual hormones into avian eggs of different species have produced inconsistent results. This might be because diverse steroids' concentrations are naturally correlated in yolks, injections are not elevating hormones at critical times in development, or injected hormones are rapidly metabolized by the developing embryo. To explore these alternatives, we injected naturally occurring levels of androstenedione (A4) and testosterone (T) or an oil control into fertile Japanese Quail (Coturnix japonica) eggs at the onset (Day 0) and/or on Day 6 of incubation. We measured the size of the embryos at two points in development (Days 6 and 15), testing for an effect of the hormone injections and the embryos' sex determined by molecular markers. Additionally, we quantified the concentrations of 27 yolk steroid hormones at five points in development (Days 0, 1, 6, 7, and 15). Ultimately, the A4 + T injection did not elevate yolk concentrations of these hormones 24 h after treatment, nor did it influence concentrations of other steroids in the yolk. Still, initial (Day 0) A4 + T injections reduced the eye diameter and leg length of female embryos and reduced the mass of male embryos on Day 6. The double hormone treatment (A4 + T on Days 0 and 6) produced embryos with larger beaks and wings but reduced mass measurements on Day 15 relative to the oil-oil control, regardless of sex. This suggests that embryonic growth responds to elevated levels of A4 and T at the beginning of incubation and in a sex- and structure-specific manner.
脊椎动物的生长速率可能会对母体提供的类固醇产生反应，然而，向不同物种的禽蛋中注射单一激素却产生了不一致的结果。这可能是因为不同类固醇的浓度在蛋黄中自然相关，注射并未在发育的关键时期提高激素水平，或者注射的激素被发育中的胚胎迅速代谢。为了探究这些可能性，我们在孵化开始时（第0天）和/或孵化第6天，向可育的日本鹌鹑（Coturnix japonica）蛋中注射天然水平的雄烯二酮（A4）和睾酮（T）或作为对照的油。我们在发育的两个时间点（第6天和第15天）测量胚胎大小，测试激素注射的效果以及通过分子标记确定的胚胎性别。此外，我们在发育的五个时间点（第0天、第1天、第6天、第7天和第15天）对27种蛋黄类固醇激素的浓度进行了量化。最终，A4 + T注射在处理后24小时并未提高这些激素在蛋黄中的浓度，也未影响蛋黄中其他类固醇的浓度。尽管如此，初始（第0天）A4 + T注射降低了雌性胚胎的眼径和腿长，并降低了第6天雄性胚胎的质量。双激素处理（第0天和第6天注射A4 + T）产生的胚胎相对于油 - 油对照，在第15天具有更大的喙和翅膀，但质量测量值降低，无论性别如何。这表明胚胎生长在孵化开始时对升高的A4和T水平有反应，且具有性别和结构特异性。
