First insights on the retroelement Rex1 in the cytogenetics of frogs

NASCIMENTO, JULIANA; BALDO, DIEGO; LOURENÇO, LUCIANA

Molecular Cytogenetics

BioMed Central

Año: 2015 vol. 8 p. 1 - 9

1755-8166

While some transposable elements (TEs) have been found in the sequenced genomesof frog species, detailed studies of these elements have been lacking. In this work, weinvestigated the occurrence of this element, which is widespread in fish, in anurans ofthe genus Physalaemus. We isolated and characterized the reverse transcriptase(RT)-coding sequences of Rex1 elements of five species of this genus.ResultsThe amino acid sequences deduced from the nucleotide sequences of the isolatedfragments allowed us to unambiguously identify regions corresponding to domains 3-7of RT. Some of the nucleotide sequences isolated from Physlaemus ephippifer and P.albonotatus had internal deletions, suggesting that these fragments are likely not activeTEs, despite being derived from a Rex1 element. When hybridized with metaphasechromosomes, Rex1 probes were revealed at the pericentromeric heterochromaticregion of the short arm of chromosome 3 of the P. ephippifer karyotype. Neither otherheterochromatin sites of the P. ephippifer karyotype nor any chromosomal regions ofthe karyotypes of P. albonotatus, P. spiniger and P. albifrons were detected with theseprobes.ConclusionsRex1 elements were found in the genomes of five species of Physalaemus butclustered in only the P. ephippifer karyotype, in contrast to observations in somespecies of fish, where large chromosomal sites with Rex1 elements are typicallypresent.