João Da Silva Marcelo, Gazoni Thiago, Haddad Célio Fernando Baptista, Parise-Maltempi Patricia Pasquali
Departamento de Biologia Geral e Aplicada, Instituto de Biociências (IB), Universidade Estadual Paulista (UNESP), São Paulo, Brazil.
Departamento de Biodiversidade e Centro de Aquicultura, Instituto de Biociências (IB), Universidade Estadual Paulista (UNESP), São Paulo, Brazil.
Front Genet. 2023 Mar 29;14:1101397. doi: 10.3389/fgene.2023.1101397. eCollection 2023.
Satellite DNAs (satDNAs) are one of the most abundant elements in genomes. Characterized as tandemly organized sequences that can be amplified into multiple copies, mainly in heterochromatic regions. The frog (2n = 22, ZZ♂/ZW♀) is found in the Brazilian Atlantic forest and has an atypical pattern of heterochromatin distribution when compared to other anuran amphibians, with large pericentromeric blocks on all chromosomes. In addition, females of have a metacentric sex chromosome W showing heterochromatin in all chromosomal extension. In this work, we performed high-throughput genomic, bioinformatic, and cytogenetic analyses to characterize the satellite DNA content (satellitome) in , mainly due to high amount of C-positive heterochromatin and the highly heterochromatic W sex chromosome. After all the analyses, it is remarkable that the satellitome of is composed of a high number of satDNA families (226), making the frog species with the highest number of satellites described so far. Consistent with the observation of large centromeric C-positive heterochromatin blocks, the genome of is enriched with high copy number of repetitive DNAs, with total satDNA abundance comprising 16.87% of the genome. We successfully mapped Fluorescence in situ hybridization the two most abundant repeats in the genome, PboSat01-176 and PboSat02-192, highlighting the presence of certain satDNAs sequences in strategic chromosomal regions (e.g., centromere and pericentromeric region), which leads to their participation in crucial processes for genomic organization and maintenance. Our study reveals a great diversity of satellite repeats that are driving genomic organization in this frog species. The characterization and approaches regarding satDNAs in this species of frog allowed the confirmation of some insights from satellite biology and a possible relationship with the evolution of sex chromosomes, especially in anuran amphibians, including , for which data were not available.
卫星DNA（satDNA）是基因组中最丰富的元件之一。其特征为串联排列的序列，可扩增为多个拷贝，主要存在于异染色质区域。这种蛙（2n = 22，ZZ♂/ZW♀）发现于巴西大西洋森林，与其他无尾两栖动物相比，具有非典型的异染色质分布模式，所有染色体上都有大的着丝粒周围区域。此外，该蛙的雌性有一条中部着丝粒性染色体W，在整个染色体区域都显示为异染色质。在这项工作中，我们进行了高通量基因组、生物信息学和细胞遗传学分析，以表征该蛙的卫星DNA含量（卫星基因组），主要是因为其大量的C阳性异染色质和高度异染色质化的W性染色体。经过所有分析，值得注意的是，该蛙的卫星基因组由大量的satDNA家族（226个）组成，使其成为迄今为止描述的卫星数量最多的蛙类物种。与观察到的大的着丝粒C阳性异染色质块一致，该蛙的基因组富含高拷贝数的重复DNA，卫星DNA的总丰度占基因组的16.87%。我们成功地通过荧光原位杂交定位了基因组中两个最丰富的重复序列，PboSat01 - 176和PboSat02 - 192，突出了某些satDNA序列在关键染色体区域（如着丝粒和着丝粒周围区域）的存在，这导致它们参与基因组组织和维持的关键过程。我们的研究揭示了驱动该蛙类物种基因组组织的卫星重复序列的巨大多样性。对该蛙类物种中satDNA的表征和研究方法，证实了卫星生物学的一些见解以及与性染色体进化的可能关系，特别是在无尾两栖动物中，包括此前尚无数据的该蛙类。
