UNESP - Univ Estadual Paulista, Instituto de Biociências/IB, Departamento de Biologia, Rio Claro, São Paulo, Brazil.
Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Sci Rep. 2017 Jul 25;7(1):6422. doi: 10.1038/s41598-017-06822-8.
Satellite DNAs (satDNAs) constitute large portion of eukaryote genomes, comprising non-protein-coding sequences tandemly repeated. They are mostly found in heterochromatic regions of chromosomes such as around centromere or near telomeres, in intercalary heterochromatin, and often in non-recombining segments of sex chromosomes. We examined the satellitome in the cricket Eneoptera surinamensis (2n = 9, neo-XXY, males) to characterize the molecular evolution of its neo-sex chromosomes. To achieve this, we analyzed illumina reads using graph-based clustering and complementary analyses. We found an unusually high number of 45 families of satDNAs, ranging from 4 bp to 517 bp, accounting for about 14% of the genome and showing different modular structures and high diversity of arrays. FISH mapping revealed that satDNAs are located mostly in C-positive pericentromeric regions of the chromosomes. SatDNAs enrichment was also observed in the neo-sex chromosomes in comparison to autosomes. Especially astonishing accumulation of satDNAs loci was found in the highly differentiated neo-Y, including 39 satDNAs over-represented in this chromosome, which is the greatest satDNAs diversity yet reported for sex chromosomes. Our results suggest possible involvement of satDNAs in genome increasing and in molecular differentiation of the neo-sex chromosomes in this species, contributing to the understanding of sex chromosome composition and evolution in Orthoptera.
卫星 DNA(satDNA)构成了真核生物基因组的大部分,由串联重复的非蛋白编码序列组成。它们主要存在于染色体的异染色质区域,如着丝粒周围或端粒附近、插人型异染色质中,并且通常存在于性染色体的非重组片段中。我们研究了蟋蟀 Eneoptera surinamensis(2n=9,neo-XXY,雄性)的卫星体,以表征其新性染色体的分子进化。为了实现这一目标,我们使用基于图的聚类和互补分析来分析 illumina 读数。我们发现了异常数量的 45 个 satDNA 家族,范围从 4bp 到 517bp,约占基因组的 14%,显示出不同的模块结构和高度的阵列多样性。FISH 作图显示,satDNA 主要位于染色体的 C 带阳性着丝粒区域。与常染色体相比,satDNA 在新性染色体上的富集也被观察到。特别令人惊讶的是,satDNA 位点在高度分化的新 Y 染色体中积累,包括在这条染色体上过度表达的 39 个 satDNA,这是迄今为止报道的性染色体上最大的 satDNA 多样性。我们的研究结果表明,satDNA 可能参与了基因组的增加和新性染色体的分子分化,这有助于理解直翅目动物的性染色体组成和进化。