Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA.
Sex Dev. 2010;4(1-2):73-87. doi: 10.1159/000260374. Epub 2009 Nov 20.
Sex determination in the American alligator depends on the incubation temperature experienced during a thermo-sensitive period (TSP), although sex determination can be 'reversed' by embryonic exposure to an estrogenic compound. Thus, temperature and estrogenic signals play essential roles during temperature-dependent sex determination (TSD). The genetic basis for TSD is poorly understood, although previous studies observed that many of the genes associated with genetic sex determination (GSD) are expressed in species with TSD. Heat shock proteins (HSPs), good candidates because of their temperature-sensitive expression, have not been examined in regard to TSD but HSPs have the ability to modify steroid receptor function. A number of HSP cDNAs (HSP27, DNAJ, HSP40, HSP47, HSP60, HSP70A, HSP70B, HSP70C, HSP75, HSP90alpha, HSP90beta, and HSP108) as well as cold-inducible RNA binding protein (CIRBP) and HSP-binding protein (HSPBP) were cloned, and expression of their mRNA in the gonadal-adrenal-mesonephros complex (GAM) was investigated. Embryonic and neonatal GAMs exhibited mRNA for all of the HSPs examined during and after the TSP. One-month-old GAMs were separated into 3 portions (gonad, adrenal gland, and mesonephros), and sexual dimorphism in the mRNA expression of gonadal HSP27 (male > female), gonadal HSP70A (male < female), and adrenal HSP90 alpha (male > female) was observed. These findings provide new insights on TSD and suggest that further studies examining the role of HSPs during gonadal development are needed.
美洲鳄的性别决定取决于胚胎在热敏期（TSP）期间经历的孵化温度，尽管胚胎暴露于雌激素化合物可以“逆转”性别决定。因此，温度和雌激素信号在温度依赖的性别决定（TSD）中起着至关重要的作用。TSD 的遗传基础理解甚少，尽管先前的研究观察到与遗传性别决定（GSD）相关的许多基因在具有 TSD 的物种中表达。热休克蛋白（HSPs）由于其温度敏感表达，是很好的候选物，尚未在 TSD 方面进行检查，但 HSPs 具有修饰甾体受体功能的能力。许多 HSP cDNA（HSP27、DNAJ、HSP40、HSP47、HSP60、HSP70A、HSP70B、HSP70C、HSP75、HSP90alpha、HSP90beta 和 HSP108）以及冷诱导 RNA 结合蛋白（CIRBP）和 HSP 结合蛋白（HSPBP）被克隆，并研究了它们在性腺-肾上腺-中肾复合体（GAM）中的 mRNA 表达。胚胎和新生儿 GAM 在 TSP 期间和之后表现出所有 HSP 的 mRNA。1 个月大的 GAM 被分为 3 部分（性腺、肾上腺和中肾），并观察到性腺 HSP27（雄性>雌性）、性腺 HSP70A（雄性<雌性）和肾上腺 HSP90 alpha（雄性>雌性）的 mRNA 表达存在性二态性。这些发现为 TSD 提供了新的见解，并表明需要进一步研究 HSP 在性腺发育过程中的作用。
