Caracterização de DNAs Satélites na Preguiça-de-dois dedos (Choloepus, Magalonychidae, Xenarthra)

Abstract

Choloepus, the single genus of the Megalonychidae family, is divided into two two-toed sloths species: C. didactylus and C. hoffmanni. In this work we identified the most abundant satellite DNAs (satDNAs) in the sequenced genome of C. hoffmanni. SATCHO1, the most abundant satDNA, corresponds to 2.6% of the genome and is composed by 117 pb sequences with low divergence among them (~2.5%). The second satDNA, SATCHO2, corresponds to 0.23% of the C. hoffmanii genome and has ~2,292 bp copies, an uncommonly large size. In situ fluorescent hibridization (FISH) in the chromosomes of C. didactylus (2n=51) allowed us to map SATCHO1 in the centromeric regions of all chromosomes, except the X. SATCHO2 was mapped to the distal regions of the short arms of 17 autosomes. PCR experiments indicated the presence of SATCHO1 sequences in two other Xenarthra species: Myrmecophaga tridactyla and Bradypus variegatus. Nevertheless, no labeling was produced after FISH in M. tridactyla chromosomes, suggesting that SATCHO1 has a satDNA pattern restricted to the genus Choloepus. Our results suggest that the analysis of repetitive DNAs in Xenarthra shall reveal important data for a better understanding of the mammalian genomes.