Institute of Animal Science, Agricultural Research Organization, Rishon LeTsiyon, Israel.
Robert H. Smith Faculty of Agriculture Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
Anim Genet. 2022 Jun;53(3):441-446. doi: 10.1111/age.13188. Epub 2022 Mar 14.
All-female culture of sturgeon is essential for efficient caviar production. However, Russian sturgeon (Acipenser gueldenstaedtii) does not exhibit external sexual dimorphism, and therefore, commercial farms apply gonadal endoscopy or ultrasound at the earliest age of 4-5 years to separate the sexes, with ~90% accuracy. Recently, a dominant genomic marker (AllWSEX2) has been found with association to femaleness in sturgeons. We developed a duplex PCR (dAllWSEX2) with the adjacent bmp7 gene as an internal control, to validate an effective PCR. Robust amplification of control fragments was observed for all samples of our commercial A. gueldenstaedtii stock (n = 337). The dAllWSEX2 assay was significantly associated with sex (n = 43, p < 1.6 × 10 ), yet four (18%) of the endoscopy-determined females were genetic males. To examine whether some females display a male genetic profile, we tested 96 egg-producing females, which were all verified as genetic females, indicating that the observed mismatches may be attributed to wrong sexing by endoscopy. Application of dAllWSEX2 on 100 7-month-old fish showed no sex-dependent differences in body weight, indicating that weighing is not an applicable tool for sorting females at a young age. Sanger sequencing of the bmp7 fragment revealed octaploidy and sex-independent variation, suggesting that the critical sex-determining region harboring AllWSEX2 is small. In keeping with a model of a single-ploidy encoding female determination, AllWSEX2 showed no variation despite being a transposase-linked repetitive element. Cross-species conservation of AllWSEX2, and absence of annotated sex-determination genes in this region suggests that, in sturgeons, the sex-determining mechanism is different from mechanisms identified in other fish.
全雌鲟鱼文化对于高效鱼子酱生产至关重要。然而，俄罗斯鲟（Acipenser gueldenstaedtii）没有表现出外部性别二态性，因此，商业养殖场在 4-5 岁的最早年龄应用性腺内窥镜或超声来分离性别，准确率约为 90%。最近，在鲟鱼中发现了一个与雌性有关的显性基因组标记（AllWSEX2）。我们开发了一种带有相邻 bmp7 基因作为内部对照的双重 PCR（dAllWSEX2），以验证有效的 PCR。在我们的商业 A. gueldenstaedtii 种群的所有样本中（n=337），都观察到了控制片段的稳健扩增。dAllWSEX2 检测与性别显著相关（n=43，p<1.6×10-5），但在 43 名内窥镜确定的雌性中，有 4 名（18%）是遗传雄性。为了检查是否有些雌性表现出雄性遗传特征，我们测试了 96 只产卵的雌性，它们都被确认为遗传雌性，这表明观察到的不匹配可能归因于内窥镜错误的性别鉴定。在 100 只 7 个月大的鱼上应用 dAllWSEX2 显示体重无性别差异，表明体重不是在幼鱼时期进行性别分类的适用工具。bmp7 片段的 Sanger 测序显示了八倍体和性别无关的变异，这表明包含 AllWSEX2 的关键性别决定区域很小。由于单一倍体编码雌性决定的模型，尽管 AllWSEX2 是一个转座酶连接的重复元件，但它没有显示出变异。AllWSEX2 在物种间的保守性，以及该区域内没有注释的性别决定基因，表明在鲟鱼中，性别决定机制与在其他鱼类中确定的机制不同。
