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1.
Cytogenet Genome Res ; 161(3-4): 195-202, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34126615

RESUMO

Ctenoluciidae (Characiformes), a family of freshwater fishes, comprises 2 genera, Ctenolucius and Boulengerella, with 7 recognized species. Up to now, only species of the genus Boulengerella have been subjected to cytogenetic studies. Here, we investigated the karyotype and other cytogenetic features of pike characin, Ctenolucius hujeta, using conventional (Giemsa staining, C-banding, Ag-NOR staining) and molecular (rDNA, telomeric sequences, and fiber-FISH mapping) procedures. This species has a diploid chromosome number of 2n = 36, and a karyotype composed of 12m + 20sm + 4a and FN = 68, similar to that found in Boulengerella species. However, differences regarding the number and distribution of several chromosomal markers support a distinct generic status. Colocalization of the 18S and 5S rDNA genes is an exclusive characteristic of the C. hujeta genome, with an interspersed distribution in the chromosomal fiber, an unusual phenomenon among eukaryotes. Additionally, our results support the view that Ctenoluciidae and Lebiasinidae families are closely related.


Assuntos
Caraciformes/genética , Cromossomos/genética , Análise Citogenética/métodos , Cariotipagem/métodos , Animais , Caraciformes/classificação , Bandeamento Cromossômico , Diploide , Evolução Molecular , Feminino , Genoma/genética , Hibridização in Situ Fluorescente/métodos , Cariótipo , Masculino , RNA Ribossômico 18S/genética , RNA Ribossômico 5S/genética , Telômero/genética
2.
Zebrafish ; 18(3): 221-230, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33847525

RESUMO

The chromosomes of the dogtooth characins, fish species of the family Cynodontidae, have only a relatively small amount of heterochromatin, including the terminal portion. Curiously, in the cynodontid Cynodon gibbus, the terminal portion is rich in repetitive DNAs, including transposable retroelements and microsatellite sequences. Given this, this study investigated the composition of the terminal portion of the chromosomes of two cynodontid species (Rhaphiodon vulpinus and Hydrolycus armatus), to compile a database for the evaluation of all three cynodontid genera, and in particular, verify the possible tendency for the accumulation of repetitive DNAs in the terminal portion of the chromosomes of C. gibbus, H. armatus, and R. vulpinus. The Rex1, Rex3, and Rex6 transposable retroelements and the (CA)15, (GA)15, (GATA)8, (GACA)8, (CAT)10, and (CAC)10 microsatellite motifs are found primarily in the terminal portion of the chromosomes of the species analyzed in this study, except R. vulpinus, which has no evidence of the presence of Rex1 or Rex3 through the fluorescent in situ hybridization technique. The mapping of the repetitive sequences, principally the microsatellite motifs, indicates a marked tendency for the accumulation of these sequences in the terminal portions of the chromosomes, which may have played a fundamental role in the differentiation of the three species.

3.
Cytogenet Genome Res ; 160(1): 29-37, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32092757

RESUMO

The fish family Cynodontidae belongs to the superfamily Curimatoidea, together with the Hemiodontidae, Serrasalmidae, Parodontidae, Prochilodontidae, Chilodontidae, Curimatidae, and Anostomidae. The majority of the species of this superfamily that have been analyzed to date have a diploid chromosome number of 2n = 54. Differentiated sex chromosomes (with female heterogamety) have been observed only in the Prochilodontidae, Parodontidae, and Anostomidae. The present study provides the first description of differentiated sex chromosomes in the cynodontid species Cynodon gibbus, which has a ZZ/ZW system, and shows that repetitive DNA has played a fundamental role in the differentiation of these sex chromosomes.


Assuntos
Caraciformes/genética , Cromossomos Sexuais , Animais , Bandeamento Cromossômico , DNA , Evolução Molecular , Feminino , Heterocromatina/química , Hibridização in Situ Fluorescente , Cariotipagem , Masculino , Hibridização de Ácido Nucleico , Sequências Repetitivas de Ácido Nucleico
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