The purpose of project was an identification of the key genes and pathways associated with final stage of oocyte maturation in birds. Novel candidate genes and pathways were identified as playing roles in protein ubiquitination and synthesis, sirtuin and estrogen receptor signaling.. Transcriptome analysis of turkey oocyte at the final stage of maturation

The germinal disc region of mature oocyte at F1 developmental stage were obtained from six 38-wk-old turkeys. The gene expression pattern were determined by high-throughput transcriptome sequencing. The obtained sequence reads were mapped to the turkey genome. Six subfamilies of zona pellucida (ZP) genes, ZP1-4, ZPD and ZPAX were identified.Bioinformatics analysis revealed that many of the identified genes were involved in key steps of protein synthesis via eIF2, elF4 and p70S6K signaling pathways and degradation via ubiquitination. Detailed analysis of transcripts classified in estrogen receptor (ESR) signalling indicated presence of ESR1 and ESR2 and a set of estrogen-dependent genes involved in both genomic and non-genomic mechanism of regulation of gene expression by estrogen.Oxidative phosphorylation was found to be a possible source of ATP in the mature bird oocyte and nuclear factor erythroid 2–related factor signaling pathway could be involved in response against oxidative stress. Here, we identified the key physiological process involved in the final stage of oocyte maturation and taking part in inner perivitelline layer preparation for fertilization. The identified genes/proteins can be potentially used to characterize the specific mechanism of bird reproduction.

本研究从6只38周龄火鸡中获取了F1发育阶段成熟卵母细胞的胚盘区域。采用高通量转录组测序（high-throughput transcriptome sequencing）确定了该区域的基因表达谱。将所得测序读段比对至火鸡参考基因组，共鉴定出透明带（zona pellucida, ZP）基因的6个亚家族，即ZP1-4、ZPD及ZPAX。生物信息学分析显示，所鉴定的多数基因通过eIF2、eIF4及p70S6K信号通路参与蛋白质合成的关键步骤，并通过泛素化途径参与蛋白质降解。对雌激素受体（estrogen receptor, ESR）信号通路相关转录本的详细分析表明，样本中存在ESR1、ESR2以及一系列参与雌激素通过基因组途径与非基因组途径调控基因表达的雌激素依赖基因。研究发现氧化磷酸化是禽类成熟卵母细胞中三磷酸腺苷（ATP）的潜在来源，而核因子红细胞2相关因子（nuclear factor erythroid 2–related factor）信号通路可能参与氧化应激应答。本研究鉴定了参与卵母细胞成熟终末期、并为受精过程中卵黄膜内层制备发挥作用的关键生理过程。所鉴定的基因/蛋白可用于解析禽类繁殖的特异性机制。