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Revisiting the Karyotypes of Alligators and Caimans (Crocodylia, Alligatoridae) after a Half-Century Delay: Bridging the Gap in the Chromosomal Evolution of Reptiles

Authors :
Vanessa C. S. Oliveira
Marie Altmanová
Patrik F. Viana
Tariq Ezaz
Luiz A. C. Bertollo
Petr Ráb
Thomas Liehr
Ahmed Al-Rikabi
Eliana Feldberg
Terumi Hatanaka
Sebastian Scholz
Alexander Meurer
Marcelo de Bello Cioffi
Source :
Cells, Vol 10, Iss 6, p 1397 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

Abstract

Although crocodilians have attracted enormous attention in other research fields, from the cytogenetic point of view, this group remains understudied. Here, we analyzed the karyotypes of eight species formally described from the Alligatoridae family using differential staining, fluorescence in situ hybridization with rDNA and repetitive motifs as a probe, whole chromosome painting (WCP), and comparative genome hybridization. All Caimaninae species have a diploid chromosome number (2n) 42 and karyotypes dominated by acrocentric chromosomes, in contrast to both species of Alligatorinae, which have 2n = 32 and karyotypes that are predominantly metacentric, suggesting fusion/fission rearrangements. Our WCP results supported this scenario by revealing the homeology of the largest metacentric pair present in both Alligator spp. with two smaller pairs of acrocentrics in Caimaninae species. The clusters of 18S rDNA were found on one chromosome pair in all species, except for Paleosuchus spp., which possessed three chromosome pairs bearing these sites. Similarly, comparative genomic hybridization demonstrated an advanced stage of sequence divergence among the caiman genomes, with Paleosuchus standing out as the most divergent. Thus, although Alligatoridae exhibited rather low species diversity and some level of karyotype stasis, their genomic content indicates that they are not as conserved as previously thought. These new data deepen the discussion of cytotaxonomy in this family.

Details

Language :
English
ISSN :
20734409
Volume :
10
Issue :
6
Database :
Directory of Open Access Journals
Journal :
Cells
Publication Type :
Academic Journal
Accession number :
edsdoj.29e8100492d4366ac2f6d0152b15f5e
Document Type :
article
Full Text :
https://doi.org/10.3390/cells10061397