In the pejerrey Odontesthes bonariensis (Atheriniformes, Atherinopsidae), exposure to high and low temperatures during the critical period of sex determination (CPSD) induce testicular and ovarian differentiation, respectively, regardless of the presence or not of the sex determining gene amhy, which is crucial for testis formation only at intermediate, sexually neutral temperatures. In this study we explored the existence of genotype-specific signaling of Crh (Corticotropin Releasing Hormone) family genes and their associated carrier protein, receptors, and other stress-related genes in response to temperature during the CPSD and the potential involvement of the central nervous system via the hypothalamus-pituitary-interrenal (HPI) axis in the sex determination of this species. The Crh family genes crhb, uts1, ucn3, the receptor crhr1 and the stress-related genes gr1, gr2, nr3c2 were transiently upregulated in the heads of pejerrey larvae during the CPSD by high temperature alone or in combination with other factors. Only crhr2 transcript abundance was not influenced by temperature but independently by time and genotype. In most cases, mRNA abundance was higher in the XX heads compared to that of XY individuals. The mRNAs of some of these genes were localized in the hypothalamus of pejerrey larvae during the CPSD. XX larvae also showed higher whole-body cortisol titers than the XY, downregulation of cyp19a1a and upregulation of the testis-related genes amhy/amha in trunks (gonads) and were 100% masculinized at the high temperature. In contrast, at the low temperature, crhbp and avt were upregulated in the heads, particularly the former in XY larvae. cyp19a1a and amhy/amha were up- and downregulated, respectively, in the gonads, and fish were 100% feminized. Signaling via the HPI axis was observed simultaneously with the first molecular signs of ongoing sex determination/differentiation in the gonads. Overall, the results strongly suggest a temperature-dependent, genotype-specific regulatory action of the brain involving the Crh family of stress-related genes on the process of environmental sex determination of pejerrey.

在pejerrey Odontesthes bonariensis （Atheriniformes，Atherinopsidae）中，在性别决定关键期（CPSD）暴露于高温和低温分别会诱导睾丸和卵巢分化，无论是否存在性别决定基因amhy ，这是仅在中等、性中性温度下对睾丸形成至关重要。在这项研究中，我们探讨了 Crh（促肾上腺皮质激素释放激素）家族基因及其相关载体蛋白、受体和其他应激相关基因在 CPSD 期间响应温度的基因型特异性信号传导的存在以及中枢神经的潜在参与系统通过下丘脑-垂体-肾间（HPI）轴来决定该物种的性别。在CPSD期间，单独高温或与其他因素联合作用下，斑鸠幼虫头部的Crh家族基因crhb、uts1、ucn3、受体crhr1和应激相关基因gr1、gr2、nr3c2短暂上调。只有crhr2转录丰度不受温度影响，而是独立于时间和基因型。在大多数情况下，与 XY 个体相比，XX 头部的 mRNA 丰度更高。在 CPSD 期间，其中一些基因的 mRNA 定位于佩杰瑞幼虫的下丘脑中。XX 幼虫还表现出比 XY 更高的全身皮质醇滴度、 cyp19a1a的下调和躯干（性腺）中睾丸相关基因amhy / amha的上调，并且在高温下 100% 雄性化。相反，在低温下，crhbp和avt在头部中表达上调，尤其是 XY 幼虫中的前者。性腺中的cyp19a1a和amhy / amha分别上调和下调，鱼类 100% 女性化。通过 HPI 轴发出的信号与性腺中正在进行的性别决定/分化的第一个分子信号同时观察到。总体而言，结果强烈表明，涉及应激相关基因 Crh 家族的大脑对佩杰瑞的环境性别决定过程存在温度依赖性、基因型特异性的调节作用。