Identification of Novel and Differentially Expressed MicroRNAs of Dairy Goat Mammary Gland Tissues Using Solexa Sequencing and Bioinformatics

MicroRNAs are small, noncoding RNA molecules that regulate gene expression at the post-transcriptional level and play an important role in various biological processes. Although most microRNAs expression profiles studies have been performed in humans or rodents, relatively limited knowledge also exists in other mammalian species. The identification of the full repertoire of microRNAs expressed in the lactating mammary gland of Capra hircus would significantly increase our understanding of the physiology of lactating mammary glands. In this study, two libraries were constructed using the lactating mammary gland tissues of Laoshan dairy goats (Capra hircus) during peak and late lactation. Solexa high-throughput sequencing technique and bioinformatics were used to determine the abundance and differential expression of the microRNAs between peak and late lactation. As a result, 19,044,002 and 7,385,833 clean reads were obtained, respectively, and 1,113 conserved known microRNAs and 31 potential novel microRNA candidates were identified. A total of 697 conserved microRNAs were significantly differentially expressed with a P-valueCapra hircus and expanded the repertoire of microRNAs. Our results have great significance and value for the elucidation of complex regulatory networks between microRNAs and mRNAs and for the study of mammary gland physiology and lactation.

微小RNA（microRNAs）是一类小型非编码RNA分子，可在转录后水平调控基因表达，且在多种生物学过程中发挥关键作用。尽管当前多数微小RNA表达谱研究多以人类或啮齿类动物为研究对象，但针对其他哺乳动物物种的相关认知仍相对有限。本研究旨在鉴定山羊（Capra hircus）泌乳乳腺中表达的全套微小RNA，这将显著提升我们对泌乳乳腺生理学的认知。本研究利用泌乳高峰期与泌乳晚期的崂山奶山羊乳腺组织构建了两个文库，采用Solexa高通量测序技术结合生物信息学方法，分析了两个时期内微小RNA的表达丰度及差异表达模式。结果共获得19,044,002与7,385,833条洁净读段（clean reads），并分别鉴定得到1113个保守的已知微小RNA以及31个潜在的新型微小RNA候选分子。共有697个保守微小RNA呈现显著差异表达（P值），本研究不仅丰富了山羊的微小RNA库，也拓展了该物种微小RNA的研究范畴。本研究结果对于阐明微小RNA与信使RNA（mRNAs）之间的复杂调控网络，以及乳腺生理学和泌乳过程的相关研究均具有重要的科学意义与应用价值。