Transcription of satellite DNA and 5-methylcytosine in parental and hybrid manatees (Trichechus manatus and Trichechus inunguis)

Satellite DNAs are essential components of centromeric regions, contributing to chromosome segregation and genome stability. Recent evidence indicates that these sequences are not merely structural elements but may also be transcriptionally active and subject to epigenetic regulation. In hybrid genomes, interactions between divergent parental epigenomes may alter the regulation of repetitive elements, potentially affecting genome stability. In this study, we investigated the centromeric satellite DNA TMAsat in the American manatees Trichechus manatus and Trichechus inunguis , as well as in their natural hybrids. An integrated approach was employed, including chromosomal localization by fluorescence in situ hybridization (FISH), gene expression analysis, and assessment of DNA methylation patterns. TMAsat FISH signals were detected in the centromeric regions of all chromosomes in both hybrid individuals analyzed, except for the Y chromosome, supporting the conservation of its chromosomal distribution in these specimens. Expression analyses revealed that TMAsat is transcribed in both parental species and the two hybrid individuals, which exhibited reduced transcript levels compared with T. inunguis . DNA methylation analyses revealed interindividual variation in global methylation levels, whereas both methylated and unmethylated TMAsat-specific products were detected in all individuals analyzed. Collectively, our findings suggest that TMAsat retains its centromeric localization and transcriptional activity in the hybrid individuals analyzed, with epigenetic modulation potentially contributing to its regulation. These results provide new insights into the functional dynamics of satellite DNA in natural hybrid systems and highlight the potential role of epigenetic mechanisms in the regulation of centromeric satellite DNA. By advancing knowledge of genome organization and epigenetic regulation in manatees, this study contributes to the United Nations Sustainable Development Goal 15 (Life on Land) by providing genetic knowledge relevant to biodiversity research and species conservation.