Aquaculture Genetics and Breeding Laboratory, The Ohio State University South Centers, Piketon, Ohio, 45661, USA.
Sci Rep. 2017 Jun 23;7(1):4196. doi: 10.1038/s41598-017-04327-y.
Terminologies of ovary development, by somewhat subjective describing and naming main changes of oocytes, have been criticized for confusing and inconsistency of terms and classifications, and the incurred consequences impede communication among researchers. In the present work, we developed regression between ovary development and three ribosome RNA (rRNA) indexes, namely 5S rRNA percent, 18S rRNA percent, and 5S-18S rRNA ratio, using close relationship between volume percent of primary growth stage oocytes or gonadosomatic index and rRNA content, demonstrating species-specific quantification of ovary development can be established in species with either synchronous and asynchronous oogenesis. This approach may be extended to any species with primary growth oocytes, e.g. anurans and reptiles, to predict maturity stages in females. We further confirmed that 5S rRNA percent and 5S/18S rRNA ratio can serve as markers to distinguish sexes unambiguously. A micro-invasive sampling method may be invented for non-lethal prediction of ovary development and sex because only a small amount of ovary sample (<50 mg) is needed for the approach established in the current work. Researchers who work with ovary RNA-seq in these taxa should realize that insufficient depletion of rRNA will probably lead to incorrect quantification of gene expression and inaccurate conclusions.
卵巢发育的术语，通过对卵母细胞主要变化的主观描述和命名，由于术语和分类的混乱和不一致而受到批评，并且由此产生的后果阻碍了研究人员之间的交流。在本工作中，我们利用初级生长阶段卵母细胞体积百分比或性腺指数与 rRNA 含量之间的密切关系，建立了卵巢发育与三种核糖体 RNA（rRNA）指标（5S rRNA 百分比、18S rRNA 百分比和 5S-18S rRNA 比值）之间的回归关系，证明在具有同步和异步卵发生的物种中，可以建立特定于物种的卵巢发育定量方法。这种方法可以扩展到任何具有初级生长卵母细胞的物种，例如蛙类和爬行动物，以预测雌性的成熟阶段。我们进一步证实，5S rRNA 百分比和 5S/18S rRNA 比值可以作为标记物，明确地区分性别。因为本工作中建立的方法只需要少量的卵巢样本（<50mg），因此可能会发明一种微创采样方法，用于非致死性预测卵巢发育和性别。在这些类群中进行卵巢 RNA-seq 研究的研究人员应该意识到，rRNA 不足可能会导致基因表达的定量不准确和结论不准确。
