Olive flounder (Paralichthys olivaceus) is a commercially important flatfish species cultured in East Asia. Female flounders generally grow more rapidly than males, therefore control of the sex ratio seems to be a proposed way to increase production. However, the sex determination gene and sex determination mechanism have yet been elucidated. The brain is an important organ that is involved in gonadal development. To explore the sex differences of gene expression in the brain before and during the flounder gonadal differentiation, we used messenger RNA (mRNA)-seq technology to investigate transcriptomes of male and female brains. Between female and male brains, 103 genes were differentially expressed before ovarian differentiation, 16 genes were differentially expressed before testicular differentiation, and 64 genes were differentially expressed during gonadal differentiation. According to annotation and Kyoto Encyclopedia of Genes and Genomes information, the differentially expressed genes (DEGs) were involved in circadian rhythm, circadian rhythm-fly, circadian entrainment, dopaminergic synapse, calcium signaling, glutamatergic synapse, taste transduction, herpes simplex infection, long-term depression, retrograde endocannabinoid signaling, and the synaptic vesicle cycle pathways. MicroRNA (miRNA)-seq was performed during the gonadal differentiation and the target genes of miRNAs were predicted. Integrated analysis of mRNA-seq and miRNA-seq showed that 29 of the 64 DEGs were regulated by the differentially expressed miRNAs during the gonadal differentiation. Our study provides a basis for further studies of brain sex differentiation and the molecular mechanism of sex determination in olive flounder.

中文翻译：

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对大脑的mRNA-seq和miRNA-seq进行的分析揭示了在17β-雌二醇或17α-甲基睾丸激素诱导的橄榄比目鱼（Paralichthys olivaceus）的性腺分化前后基因表达和调控的性别差异。

比目鱼（Paralichthys olivaceus）是在东亚养殖的商业上重要的比目鱼物种。雌性比目鱼通常比雄性比增长快，因此控制性别比似乎是提高产量的一种建议方法。然而，性别决定基因和性别决定机制尚未阐明。大脑是参与性腺发育的重要器官。为了探索比目鱼性腺分化之前和过程中大脑中基因表达的性别差异，我们使用了信使RNA（mRNA）-seq技术研究了男性和女性大脑的转录组。在雌性和雄性大脑之间，卵巢分化前差异表达了103个基因，睾丸分化前差异表达了16个基因，性腺分化过程中有64个基因差异表达。根据注释和《京都市基因与基因组百科全书》的信息，差异表达基因（DEG）参与了昼夜节律，昼夜节律飞行，昼夜节律，多巴胺能突触，钙信号传导，谷氨酸能突触，味觉转导，单纯疱疹感染，长期感染长期抑郁，逆行内源性大麻素信号传导和突触小泡循环途径。在性腺分化过程中进行了microRNA（miRNA）-seq，并预测了miRNA的靶基因。对mRNA-seq和miRNA-seq的综合分析表明，在性腺分化过程中，64个DEG中有29个受差异表达的miRNA调控。