The presence of the Y-chromosome, not the absence of the second X-chromosome, alters the mRNA levels stored in the fully grown XY mouse oocyte

The oocytes of B6.Y(TIR) sex-reversed female mouse mature in culture but fail to develop after fertilization because of their cytoplasmic defects. To identify the defective components, we compared the gene expression profiles between the fully-grown oocytes of B6.Y(TIR) (XY) females and those of their XX littermates by cDNA microarray. 173 genes were found to be higher and 485 genes were lower in XY oocytes than in XX oocytes by at least 2-fold. We compared the transcript levels of selected genes by RT-PCR in XY and XX oocytes, as well as in XO oocytes missing paternal X-chromosomes. All genes tested showed comparable transcript levels between XX and XO oocytes, indicating that mRNA accumulation is well adjusted in XO oocytes. By contrast, in addition to Y-encoded genes, many genes showed significantly different transcript levels in XY oocytes. We speculate that the presence of the Y-chromosome, rather than the absence of the second X-chromosome, caused dramatic changes in the gene expression profile in the XY fully-grown oocyte. We compared the gene expression profiles between the fully-grown oocytes of B6.Y(TIR) (XY) females and those of their XX littermates by cDNA microarray Mouse GV oocytes of B6.Y(TIR) were collected for RNA extraction and hybridization to Affymetrix microarray. We sought to extract the differentially expressed genes in the XY oocytes.B6.Y(TIR)性反转雌性小鼠的卵母细胞虽可在体外成熟，但受精后因细胞质缺陷无法正常发育。为鉴定其中的缺陷组分，我们通过cDNA微阵列（cDNA microarray）比较了B6.Y(TIR)（XY）雌性与同窝XX雌性的完全生长型卵母细胞的基因表达谱。结果显示，相较于XX卵母细胞，XY卵母细胞中有173个基因表达上调、485个基因表达下调，差异幅度至少为2倍。我们通过逆转录聚合酶链式反应（RT-PCR）检测了部分候选基因在XY、XX以及缺失父本X染色体的XO卵母细胞中的转录水平。所有受检基因在XX与XO卵母细胞中的转录水平均无显著差异，提示XO卵母细胞的mRNA积累过程调控正常。与之形成鲜明对比的是，除Y染色体编码的基因外，诸多基因在XY卵母细胞中的转录水平存在显著差异。我们推测，是Y染色体的存在而非第二条X染色体的缺失，导致XY完全生长型卵母细胞的基因表达谱发生剧烈改变。我们再次通过cDNA微阵列比较了B6.Y(TIR)（XY）雌性与同窝XX雌性的完全生长型卵母细胞的基因表达谱。本研究收集了B6.Y(TIR)小鼠的生发泡（GV）卵母细胞用于RNA提取，并将其与Affymetrix微阵列进行杂交实验。我们的研究目标为筛选XY卵母细胞中的差异表达基因。