Western P S, Harry J L, Marshall Graves J A, Sinclair A H
Department of Paediatrics and Centre for Hormone Research, University of Melbourne, Royal Children's Hospital, Victoria, Australia.
Gene. 2000 Jan 11;241(2):223-32. doi: 10.1016/s0378-1119(99)00466-7.
Sex determination in mammals and birds is chromosomal, while in many reptiles sex determination is temperature dependent. Morphological development of the gonads in these systems is conserved, suggesting that many of the genes involved in gonad development are also conserved. The genes SF1, WT1 and DAX1 play various roles in the mammalian testis-determining pathway. SF1 and WT1 are thought to interact to cause male-specific gene expression during testis development, while DAX1 is believed to inhibit this male-specific gene expression. We have cloned SF1 and DAX1 from the American alligator, a species with temperature-dependent sex determination (TSD). SF1, DAX1 and WT1 are expressed in the urogenital system/gonad throughout the period of alligator gonadogenesis which is temperature sensitive. SF1 appears to be expressed at a higher level in females than in males. This SF1 expression pattern is concordant with the observed pattern during chicken gonadogenesis, but opposite to that observed during mouse gonadogenesis. Although the observed sexual dimorphism of gonadal SF1 expression in alligators and chickens is opposite that observed in the mouse, it is probable that SF1 is involved in control of gonadal steroidogenesis in all these vertebrates. DAX1 and WT1 are both expressed during stages 22-25 of both males and females. However, there appear to be no sex differences in the expression patterns of these genes. We conclude that DAX1, WT1 and SF1 may be involved in gonadal development of the alligator. These genes may form part of a gonadal-development pathway which has been conserved through vertebrate evolution.
哺乳动物和鸟类的性别决定是由染色体决定的，而在许多爬行动物中，性别决定则取决于温度。这些系统中生殖腺的形态发育是保守的，这表明许多参与生殖腺发育的基因也是保守的。基因SF1、WT1和DAX1在哺乳动物的睾丸决定途径中发挥着各种作用。SF1和WT1被认为相互作用，从而在睾丸发育过程中导致雄性特异性基因表达，而DAX1则被认为会抑制这种雄性特异性基因表达。我们已经从美洲短吻鳄（一种具有温度依赖型性别决定（TSD）的物种）中克隆出了SF1和DAX1。在美洲短吻鳄生殖腺发生的整个温度敏感时期，SF1、DAX1和WT1在泌尿生殖系统/生殖腺中表达。SF1在雌性中的表达水平似乎高于雄性。这种SF1的表达模式与在鸡生殖腺发生过程中观察到的模式一致，但与在小鼠生殖腺发生过程中观察到的模式相反。尽管在美洲短吻鳄和鸡中观察到的生殖腺SF1表达的性别二态性与在小鼠中观察到的相反，但SF1很可能在所有这些脊椎动物的生殖腺类固醇生成控制中发挥作用。DAX1和WT1在雄性和雌性的第22 - 25阶段均有表达。然而，这些基因的表达模式似乎没有性别差异。我们得出结论，DAX1、WT1和SF1可能参与了美洲短吻鳄的生殖腺发育。这些基因可能构成了一个在脊椎动物进化过程中保守的生殖腺发育途径的一部分。
