Xenopus laevis is an amphibian (frog) species widely used in developmental biology and genetics. To unravel the molecular machinery regulating sex differentiation of Xenopus gonads, we analyzed for the first time the transcriptome of developing amphibian gonads covering sex determination period. We applied microarray at four developmental stages: (i) NF50 (undifferentiated gonad during sex determination), (ii) NF53 (the onset of sexual differentiation of the gonads), (iii) NF56 (sexual differentiation of the gonads), and (iv) NF62 (developmental progression of differentiated gonads). Our analysis showed that during the NF50, the genetic female (ZW) gonads expressed more sex-specific genes than genetic male (ZZ) gonads, which suggests that a robust genetic program is realized during female sex determination in Xenopus. However, a contrasting expression pattern was observed at later stages (NF56 and NF62), when the ZW gonads expressed less sex-specific genes than ZZ gonads, i.e., more genes may be involved in further development of the male gonads (ZZ). We identified sexual dimorphism in the expression of several functional groups of genes, including signaling factors, proteases, protease inhibitors, transcription factors, extracellular matrix components, extracellular matrix enzymes, cell adhesion molecules, and epithelium-specific intermediate filaments. In addition, our analysis detected a sexually dimorphic expression of many uncharacterized genes of unknown function, which should be studied further to reveal their identity and if/how they regulate gonad development, sex determination, and sexual differentiation. Comparison between genes sex-specifically expressed in developing gonads of Xenopus and available transcriptome data from zebrafish, two reptile species, chicken, and mouse revealed significant differences in the genetic control of sex determination and gonad development. This shows that the genetic control of gonad development is evolutionarily malleable.

中文翻译：

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转录组分析揭示了男性和女性特异性基因表达模式和新的候选基因，用于控制非洲爪蟾的性别决定和性腺发育。

非洲爪蟾是一种两栖类（青蛙），广泛用于发育生物学和遗传学。揭示调控非洲爪蟾性别分化的分子机制性腺，我们首次分析了涵盖性别决定时期的发育中的两栖性腺的转录组。我们在四个发育阶段应用了微阵列：（i）NF50（在性别确定过程中未分化的性腺），（ii）NF53（性腺的性分化开始），（iii）NF56（性腺的性分化）和（iv ）NF62（分化性腺的发育过程）。我们的分析表明，在NF50期间，遗传雌性（ZW）性腺比遗传雄性（ZZ）性腺表达更多的性别特异性基因，这表明非洲爪蟾女性性别确定过程中实现了强大的遗传程序。。然而，当ZW性腺表达的性别特异性基因少于ZZ性腺时，在后期（NF56和NF62）会观察到相反的表达模式，即，男性性腺（ZZ）的进一步发育可能涉及更多的基因。我们在基因的几个功能组的表达中发现了性二态性，包括信号传导因子，蛋白酶，蛋白酶抑制剂，转录因子，细胞外基质成分，细胞外基质酶，细胞粘附分子和上皮特异性中间丝。此外，我们的分析检测到许多未知功能未知基因的性别双态表达，应进一步研究它们的身份，以及它们是否/如何调控性腺发育，性别决定和性别分化。爪蟾和斑马鱼，两种爬行动物，鸡和小鼠的可用转录组数据显示，性别控制和性腺发育的遗传控制存在显着差异。这表明性腺发育的遗传控制是可进化的。