Karyotype diversity and patterns of chromosomal evolution in Eigenmannia (Teleostei, Gymnotiformes, Sternopygidae).

Content Provider	Europe PMC
Author	Sene, Viviani França Pansonato-Alves, José Carlos Utsunomia, Ricardo Oliveira, Claudio Foresti, Fausto
Abstract	AbstractConventional (Giemsa, C-banding, Ag – NORs) and molecular [5S rDNA, 18S rDNA, (TTAGGG)n] cytogenetic techniques were employed to study six species of the genus Eigenmannia Jordan & Evermann, 1896. They exhibited diploid chromosome numbers ranging from 2n=28 (Eigenmannia sp.1) to 2n=38 (Eigenmannia virescens (Valenciennes, 1836)). The C-banding results revealed that species with the lowest 2n have less heterochromatin content and that morphologically differentiated sex chromosomes observed in two species showed distinct patterns of heterochromatin. While the X1, X2 and Y-chromosomes of Eigenmannia sp.2 showed only centromeric heterochromatin, the XY sex chromosomes of Eigenmannia virescens possessed large heterochromatic blocks in the terminal position, particularly on the X chromosome. The nucleolus organizer regions (NORs) were located in different positions when compared to the 5S rDNA sites. Additionally, the presence of minor ribosomal gene sites on the sex chromosome pair of Eigenmannia virescens represented a new type of the sex chromosomes in this group. The telomeric probe (TTAGGG)n hybridized to the terminal portion of all chromosomes in all species examined however, interstitial telomeric sites were found in the metacentric pair No. 2 in Eigenmannia sp.1. The analyzes confirmed some hypotheses about karyotype evolution in the genus Eigenmannia, and brought new information about the distribution of the genetic material in the chromosomes of the samples analyzed providing new insights for understanding the process differentiation in the genomes of species under study.
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ISSN	19930771
Journal	Comparative Cytogenetics [Comp Cytogenet]
Volume Number	8
PubMed Central reference number	PMC4296717
Issue Number	4
PubMed reference number	25610544
e-ISSN	1993078X
DOI	10.3897/compcytogen.v8i4.8396
Language	English
Publisher	Pensoft Publishers
Publisher Date	2014-11-17
Access Restriction	Open
Rights License	This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Viviani França Sene, José Carlos Pansonato-Alves, Ricardo Utsunomia, Claudio Oliveira, Fausto Foresti
Subject Keyword	Fish comparative cytogenetics electric fishes chromosome banding rDNA variability sex chromosomes
Content Type	Text
Resource Type	Article
Subject	Genetics Plant Science Animal Science and Zoology Biotechnology Insect Science