Chromosomal Instability and Origin of B Chromosomes in the Amazonian Glass Tetra Moenkhausia oligolepis (Günther, 1864) (Characiformes, Characidae).

Autor:	Dos Santos LP; Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia, Brazil., Francisco CM; Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia, Brazil., Campos Júnior EO; Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia, Brazil., Castro JP; Post-Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Ponta Grossa, Brazil., Utsunomia R; Department of Genetics, Institute of Biological and Health Sciences, ICBS, Federal Rural University of Rio de Janeiro, Seropédica, Brazil., Morelli S; Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia, Brazil., Porto-Foresti F; Department of Biological Sciences, Faculty of Sciences, Paulista State University (UNESP), Bauru, Brazil., Foresti F; Department of Structural and Functional Biology, Botucatu Biosciences Institute, Paulista State University (UNESP), Botucatu, Brazil., Artoni RF; Post-Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Ponta Grossa, Brazil.
Jazyk:	angličtina
Zdroj:	Cytogenetic and genome research [Cytogenet Genome Res] 2021; Vol. 161 (5), pp. 249-256. Date of Electronic Publication: 2021 Aug 25.
DOI:	10.1159/000517091
Abstrakt:	B chromosomes occur in different species of the small characid fishes of the genus Moenkhausia. These supernumerary elements, that do not recombine with chromosomes of the standard A complement and follow their own evolutionary mechanism vary in number, morphology, and distribution. Here, we show karyotypic data of individuals of 2 populations of Moenkhausia oligolepis of the Brazilian Amazon (Pedro Correia and Taboquinha streams, Tocantins river basin), both with a diploid number of 50 chromosomes and karyotypic formula of 10m + 32sm + 8a. In addition to the normal complement, we also observed the occurrence of B chromosomes in the 2 populations with intra- and interindividual variation ranging from 0 to 10 Bs, independent of sex. The C-banding pattern evidenced heterochromatic blocks located mainly in the pericentromeric region of the chromosomes, while the B chromosomes appeared euchromatic. Silver-stained nucleolus organizer regions were identified in multiples sites, and some of these blocks were positive when stained with chromomycin A3. The karyotype analysis and the application of whole-chromosome painting in populations of M. oligolepis reinforce the conservation of the basal diploid number for the genus, as well as the evolutionary tendency in these fishes to carry B chromosomes. Both populations turned out to be in different stages of stability and expansion of their B chromosomes. We further suggest that the origin of these chromosomes is due to the formation of isochromosomes. Here, we identified a pair of complement A chromosomes involved in this process. (© 2021 S. Karger AG, Basel.)
Databáze:	MEDLINE
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