Rupp Shawn M, Webster Timothy H, Olney Kimberly C, Hutchins Elizabeth D, Kusumi Kenro, Wilson Sayres Melissa A
School of Life Sciences, Arizona State University, Tempe, AZ, USA.
Center for Evolution and Medicine, The Biodesign Institute at Arizona State University, Tempe, AZ, USA.
Genome Biol Evol. 2017 Jan 1;9(1):231-240. doi: 10.1093/gbe/evw263.
In species with highly heteromorphic sex chromosomes, the degradation of one of the sex chromosomes will result in unequal gene expression between the sexes (e.g. between XX females and XY males) and between the sex chromosomes and the autosomes. Dosage compensation is a process whereby genes on the sex chromosomes achieve equal gene expression. We compared genome-wide levels of transcription between males and females, and between the X chromosome and the autosomes in the green anole, Anolis carolinensis. We present evidence for dosage compensation between the sexes, and between the sex chromosomes and the autosomes. When dividing the X chromosome into regions based on linkage groups, we discovered that genes in the first reported X-linked region, anole linkage group b (LGb), exhibit complete dosage compensation, although the rest of the X-linked genes exhibit incomplete dosage compensation. Our data further suggest that the mechanism of this dosage compensation is upregulation of the X chromosome in males. We report that approximately 10% of coding genes, most of which are on the autosomes, are differentially expressed between males and females. In addition, genes on the X chromosome exhibited higher ratios of nonsynonymous to synonymous substitution than autosomal genes, consistent with the fast-X effect. Our results from the green anole add an additional observation of dosage compensation in a species with XX/XY sex determination.
在具有高度异形性染色体的物种中，其中一条性染色体的退化会导致两性之间（例如XX雌性和XY雄性之间）以及性染色体与常染色体之间基因表达的不平等。剂量补偿是一个过程，通过这个过程性染色体上的基因实现平等的基因表达。我们比较了绿安乐蜥（Anolis carolinensis）雄性和雌性之间以及X染色体与常染色体之间全基因组水平的转录情况。我们提供了两性之间以及性染色体与常染色体之间剂量补偿的证据。当根据连锁群将X染色体划分为不同区域时，我们发现首次报道的X连锁区域（安乐蜥连锁群b，LGb）中的基因表现出完全的剂量补偿，尽管其余的X连锁基因表现出不完全的剂量补偿。我们的数据进一步表明这种剂量补偿的机制是雄性中X染色体的上调。我们报告称，大约10%的编码基因（其中大部分位于常染色体上）在雄性和雌性之间存在差异表达。此外，X染色体上的基因比常染色体基因表现出更高的非同义替换与同义替换比率，这与快速X效应一致。我们从绿安乐蜥获得的结果为XX/XY性别决定物种中的剂量补偿增添了新的观察结果。
