中文摘要：

猪（Sus scrofa）是一种重要的经济动物,研究发现瘦肉型猪的血清甲状腺激素水平高于脂肪型猪。Micro RNA（miRNA）参与调控多种生物学过程,但其在猪甲状腺激素调控中的作用尚不清楚。本研究以去势的120日龄的金华猪（脂肪型）和约克夏猪（瘦肉型）为研究对象,利用高通量测序技术分析其甲状腺组织中的miRNA表达情况,共检测到353个miRNA,包括293个已知miRNA和60个新预测的miRNA。其中有15个miRNA在两种猪的甲状腺中都高表达,这些miRNA被报道与甲状腺的生物学功能关系紧密。金华猪相对于约克夏猪存在18个差异表达miRNA,包括12个上调和6个下调。对差异表达的miRNA进行靶基因预测,共获得14 913个靶基因,经靶基因功能分析发现,这些miRNA主要参与了甲状腺激素合成、内吞作用、钙信号通路、过氧化物酶体和溶酶体等甲状腺激素调控相关的通路。本研究首次对猪甲状腺中miRNA表达谱进行了分析,将补充甲状腺激素调控网络中miRNA的作用,并在miRNA水平上为瘦肉型猪和脂肪型猪的遗传差异提供研究基础。

英文摘要：

Pig （Sus scrofa） is an important economic animal. Studies have found that the serum thyroid hormone levels of lean pigs are higher than those of obese pigs. MicroRNAs （miRNAs） play important roles in various biological processes. Despite a significant improvement in the identification of miRNAs in porcine tissues, the coverage of the porcine thyroid miRNAome is still scarce. In this study, castrated Jinhua （obese pigs） and Yorkshire pigs （lean pigs） at age of 120-days-old were used to delineate the expression profiles of miRNAs with high throughput sequencing. The number of raw reads of each transcriptome ranged from 11 to 12 million. After low quality sequences, polyA, sequences shorter than 18 or longer than 30 nucleotides, and repeated sequences were removed, the number of clean reads from each thyroid miRNA transcriptome decreased to 10-11 million. The small RNA length distribution showed that the most abundant species were 21-24 nucleotides, a typical size range for Dicer-derived products. Totally 293 known miRNAs were successfully identified in porcine thyroid gland. Besides, 60 novel microRNAs were predicted by using miREvo and mirdeap2 software. After expression levels of miRNAs were normalized to transcripts per million （TPM）, a total of 15 miRNAs were found to be expressed at high levels （〉 10 000）, including ssc-miR-148a- 3p, ssc-miR-30a-5p, ssc-miR-99a, ssc-miR-27b-3p, ssc-let-7f, ssc-miR-26a, ssc-let-7i, ssc-let-7g, ssc-miR-21, ssc-miR-7, ssc-miR- 126-3p, ssc-miR-30d, ssc-miR- 10a-5p, ssc-miR- 143-3p and ssc-let-7a. This set of miRNAs may play important housekeeping roles in thyroid gland. DESeq was used to analyze the differentially expressed miRNAs in 2 pig breeds. In our study, 18 miRNAs were found with differential expression levels between Yorkshire and Jinhua pigs （P〈0.05）, 6 miRNAs had a higher expression level in Yorkshire （ssc- miR- 532- 3p, ssc- miR- 708- 5p, ssc- miR- 129a- 5p, ssc- miR- 708- 3p, novel_7 and ssc- miR- 362）, whereas 12 miRNAs in Jinhua ?