Identificação de novo e caracterização de DNAs satélites em macacos-de-cheiro (Saimiri, Cebidae, Platyrrhini) e peixes-boi (Trichechus, Trichechidae, Sirenia)

Abstract

Repetitive DNA sequences are present in most eukaryotic genomes. A fraction of the repetitive portion is composed of satellite DNA (satDNAs), long arrays of tandemly repeated sequences that even without encoding proteins display important biological roles in genome maintenance and regulation. In spite of this, they are still an underexplored fraction of most mammalian genome. In chapter 1, we characterized two satDNAs present in four neotropical primate species from the Saimiri genus. We identified the alfa and CapA satDNAs from the analysis of the S. boliviensis sequenced genome using the RepeatExplorer software. The alfa centromeric satDNA has ~340 bp and high interspecific sequence homogeneity. CapA, on the other hand, has monomers of around 1,500 bp and is mainly present in the subtelomeric regions of the submetacentric chromosomes and in some interstitial regions, but with variable location among Saimiri species. The CapA location, associated with other information, such as the fundamental autosomal number, may help in the classification of species present of the genus, whose number and phylogenetic relationships have always been a matter of debate. In chapter 2, using the manatee Trichechus manatus sequenced genome and the TAREAN software, we identified and characterized TMAsat, the first satDNA described in the group and present in the two Sirenia families. TMAsat is about 687 bp and has a centromeric location in T. manatus and T. inunguis. We also detected this satDNA in D. dugon and H. gigas (an extinct species). A comparative analysis of TMAsat monomers in these four species did not indicate species-specific sequences despite the ~43 Ma divergence between Trichechidae and Dugongidae, in disagreement with the prediction of Combined Evolution. We detected the ancestral TMAsatlike sequence in elephants and hiraxes, without the typical satDNA pattern in these genomes, indicating that the TMAsat sequence expanded as a satDNA in Sirenia less than 69 Ma.