Hatkevich Talia, Tezak Boris M, Acemel Rafael D, Yee Chung Vicky Wai, Lupiáñez Dario G, Capel Blanche
Department of Cell Biology, Duke University Medical Center, Durham, NC 27701.
Biology Department, Wesleyan University, Middletown, CT 06459.
Proc Natl Acad Sci U S A. 2025 Jan 7;122(1):e2413191121. doi: 10.1073/pnas.2413191121. Epub 2024 Dec 30.
In species with genetic sex determination (GSD), the sex identity of the soma determines germ cell fate. For example, in mice, XY germ cells that enter an ovary differentiate as oogonia, whereas XX germ cells that enter a testis initiate differentiation as spermatogonia. However, numerous species lack a GSD system and instead display temperature-dependent sex determination (TSD). In the red-eared slider turtle, , a TSD model species with a warm female promoting temperature (FPT) and cool male promoting temperature (MPT) system, temperature directly affects germ cell number. In this study, we examined whether temperature directly affects other aspects of germ cell differentiation/sex identity. We uncoupled temperature and the sexual fate of the gonad by incubating eggs at MPT and treating with 17β-estradiol, a scheme that invariably produces ovaries. Through analysis of meiotic spreads, we showed that germ cells in FPT ovaries follow the typical pattern of initiating meiosis and progress through prophase I. However, in E2-induced ovaries that incubated at MPT, germ cells entered prophase I yet fail to exhibit synapsis. These results, combined with our single-cell transcriptome analysis, reveal a direct effect of temperature on germ cell sexual differentiation independent of its effect on the gonadal soma. These results imply that not all events of meiosis are under somatic control, at least not in this TSD species.
在具有遗传性别决定（GSD）的物种中，体细胞的性别身份决定生殖细胞的命运。例如，在小鼠中，进入卵巢的XY生殖细胞分化为卵原细胞，而进入睾丸的XX生殖细胞则开始分化为精原细胞。然而，许多物种缺乏GSD系统，而是表现出温度依赖性性别决定（TSD）。在红耳龟中，这是一种具有温暖雌性促进温度（FPT）和凉爽雄性促进温度（MPT）系统的TSD模式物种，温度直接影响生殖细胞数量。在本研究中，我们研究了温度是否直接影响生殖细胞分化/性别身份的其他方面。我们通过在MPT下孵育卵并用17β-雌二醇处理来解除温度与性腺性命运的关联，该方案总是产生卵巢。通过减数分裂铺片分析，我们表明FPT卵巢中的生殖细胞遵循启动减数分裂并通过前期I进展的典型模式。然而，在MPT下孵育的E2诱导的卵巢中，生殖细胞进入前期I但未能表现出联会。这些结果，结合我们的单细胞转录组分析，揭示了温度对生殖细胞性别分化的直接影响，独立于其对性腺体细胞的影响。这些结果意味着并非所有减数分裂事件都受体细胞控制，至少在这个TSD物种中不是。
