Repetitive Sequence Distribution on Saguinus, Leontocebus and Leontopithecus Tamarins (Platyrrhine, Primates) by Mapping Telomeric (TTAGGG) Motifs and rDNA Loci.

Sofia Mazzoleni,Polina L Perelman,Michail Rovatsos,Simona Ceraulo,Francesca Dumas

doi:10.3390/biology10090844

Abstract

Tamarins are a distinct group of small sized New World monkeys with complex phylogenetic relationships and poorly studied cytogenetic traits. In this study, we applied molecular cytogenetic analyses by fluorescence in situ hybridization with probes specific for telomeric sequences and ribosomal DNA loci after DAPI/CMA3 staining on metaphases from five tamarin species, namely Leontocebus fuscicollis, Leontopithecus rosalia, Saguinus geoffroyi, Saguinus mystax and Saguinus oedipus, with the aim to investigate the distribution of repetitive sequences and their possible role in genome evolution. Our analyses revealed that all five examined species show similar karyotypes, 2n = 46, which differ mainly in the morphology of chromosome pairs 16-17 and 19-22, due to the diverse distribution of rDNA loci, the amplification of telomeric-like sequences, the presence of heterochromatic blocks and/or putative chromosomal rearrangements, such as inversions. The differences in cytogenetic traits between species of tamarins are discussed in a comparative phylogenetic framework, and in addition to data from previous studies, we underline synapomorphies and apomorphisms that appeared during the diversification of this group of New World monkeys.

Highlights

Among New World monkeys, the subfamily Callitrichinae (Cebidae; Platyrrhini) represents one of the richest groups in terms of species and phenotypic variation
In contrast to a previous study, where classic silver stain permitted the detection of active Nucleolus Organizer Regions (NORs) [11,29], we found both active and inactive ribosomal DNA (rDNA) loci in the species of the genus Saguinus
The different morphology of chromosome pairs 19–22 is due to the fact that rDNA loci are found on the q arm in the genera Leontocebus and Saguinus and on the p arm in Leontopithecus rosalia, where we show an extensive hybridisation signal (Figures 2 and 3)

Summary

Introduction

Among New World monkeys, the subfamily Callitrichinae (Cebidae; Platyrrhini) represents one of the richest groups in terms of species and phenotypic variation It consists of 48 currently recognised species [1] assigned to three tamarin genera (Saguinus, Leontocebus and Leontopithecus) and four marmoset genera (Callithrix, Cebuella, Callimico and Mico). The position of the genera Leontopithecus and Saguinus (tamarins) was controversial, with either Saguinus or Leontopithecus considered as basal [2]; the most recent phylogenetic arrangements assign the genus Saguinus as the most basal lineage, followed by Leontopithecus, Callimico, Callithrix, Mico and Cebuella in agreement with the phyletic dwarfism hypothesis. The species of the genus Saguinus have rather similar G-banded karyotypes with differences in heterochromatin distribution, as revealed by a C-banding comparison

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Conclusion