INRA, UR SCRIBE, IFR, BioGenOuest, Rennes, France.
Gene. 2011 Feb 1;472(1-2):7-17. doi: 10.1016/j.gene.2010.10.014. Epub 2010 Oct 31.
The gonadal soma-derived factor (GSDF) belongs to the transforming growth factor-β superfamily and is conserved in teleostean fish species. Gsdf is specifically expressed in the gonads, and gene expression is restricted to the granulosa and Sertoli cells in trout and medaka. The gsdf gene expression is correlated to early testis differentiation in medaka and was shown to stimulate primordial germ cell and spermatogonia proliferation in trout. In the present study, we show that the gsdf gene localizes to a syntenic chromosomal fragment conserved among vertebrates although no gsdf-related gene is detected on the corresponding genomic region in tetrapods. We demonstrate using quantitative RT-PCR that most of the genes localized in the synteny are specifically expressed in medaka gonads. Gsdf is the only gene of the synteny with a much higher expression in the testis compared to the ovary. In contrast, gene expression pattern analysis of the gsdf surrounding genes (nup54, aff1, klhl8, sdad1, and ptpn13) indicates that these genes are preferentially expressed in the female gonads. The tissue distribution of these genes is highly similar in medaka and zebrafish, two teleostean species that have diverged more than 110 million years ago. The cellular localization of these genes was determined in medaka gonads using the whole-mount in situ hybridization technique. We confirm that gsdf gene expression is restricted to Sertoli and granulosa cells in contact with the premeiotic and meiotic cells. The nup54 gene is expressed in spermatocytes and previtellogenic oocytes. Transcripts corresponding to the ovary-specific genes (aff1, klhl8, and sdad1) are detected only in previtellogenic oocytes. No expression was detected in the gonocytes in 10 dpf embryos. In conclusion, we show that the gsdf gene localizes to a syntenic chromosomal fragment harboring evolutionary conserved genes in vertebrates. These genes are preferentially expressed in previtelloogenic oocytes, and thus, they display a different cellular localization compared to that of the gsdf gene indicating that the later gene is not co-regulated. Interestingly, our study identifies new clustered genes that are specifically expressed in previtellogenic oocytes (nup54, aff1, klhl8, sdad1).
性腺基质衍生因子（GSDF）属于转化生长因子-β超家族，在硬骨鱼类中保守。Gsdf 特异性表达于性腺，在鳟鱼和日本青鳉中基因表达仅限于颗粒细胞和支持细胞。Gsdf 基因表达与日本青鳉的早期睾丸分化相关，并被证明能刺激原始生殖细胞和精原细胞在鳟鱼中的增殖。在本研究中，我们发现 gsdf 基因定位于脊椎动物保守的同源染色体片段上，尽管在四足动物的相应基因组区域未检测到 gsdf 相关基因。我们通过定量 RT-PCR 证明，大多数定位于该同源性区域的基因在日本青鳉的性腺中特异性表达。Gsdf 是该同源性区域中唯一在睾丸中表达水平远高于卵巢的基因。相比之下，gsdf 周围基因（nup54、aff1、klhl8、sdad1 和 ptpn13）的基因表达模式分析表明，这些基因在雌性性腺中优先表达。这些基因在日本青鳉和斑马鱼中的组织分布非常相似，斑马鱼是一种与日本青鳉分化超过 1.1 亿年的硬骨鱼类。我们使用整体原位杂交技术在日本青鳉的性腺中确定了这些基因的细胞定位。我们证实 gsdf 基因表达仅限于与减数前期和减数分裂细胞接触的支持细胞和颗粒细胞。Nup54 基因在精母细胞和前卵黄生成卵母细胞中表达。仅在前卵黄生成卵母细胞中检测到卵巢特异性基因（aff1、klhl8 和 sdad1）的转录本。在 10 dpf 胚胎的性原细胞中未检测到表达。总之，我们发现 gsdf 基因定位于脊椎动物同源染色体片段上，该片段包含进化上保守的基因。这些基因在前卵黄生成卵母细胞中优先表达，因此与 gsdf 基因的细胞定位不同，表明后者基因不是共同调控的。有趣的是，我们的研究鉴定了新的簇状基因，这些基因特异性表达于前卵黄生成卵母细胞（nup54、aff1、klhl8、sdad1）。
