IS Callichtys LINNÉ (OSTARIOPHISY, SILURIFORMES, CALLICHTHYIDAE) A MONOTYPIC GENUS?

Porto, Jorge Ivan Rebelo; Feldberg, Eliana

doi:10.1590/1809-43921993233314

Cited by 8 publications

(10 citation statements)

References 1 publication

(1 reference statement)

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“…On the present study, the analyzed population shows the same pattern, except for two individuals. These individuals showed the presence of a third NOR bearing chromosome, similar to a situation described for one individual by Porto & Feldberg (1993). The presence of an additional chromosome bearing NORs is a recurring condition for C. callichthys.…”

Section: Discussionsupporting

confidence: 78%

B chromosome and NORs polymorphism in Callichthys callichthys (Linnaeus, 1758) (Siluriformes: Callichthyidae) from upper Paraná River, Brazil

et al. 2014

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B chromosomes are extra chromosomes from the normal chromosomal set, found in different organisms, highlighting their presence on the group of fishes. Callichthys callichthys from the upper Paraná River has a diploid number of 56 chromosomes (26 m-sm + 30 st-a) for both sexes, with the presence of a sporadically acrocentric B chromosome. Moreover, one individual presented a diploid number of 57 chromosomes, with the presence of a morphologically ill-defined acrocentric B chromosome in all analyzed cells. The physical mapping of 5S and 18S rDNA shows multiple 5S rDNA sites and only one pair of chromosomes with 18S sites in C. callichthys, except for two individuals. These two individuals presented a third chromosome bearing NORs (Ag-staining and 18S rDNA) where 5S and 18S rDNA genes are syntenic, differing only in position. The dispersion of the 18S rDNA genes from the main st-a chromosome pair 25 to one of the chromosomes from the m-sm pair 4 would have originated two variant individuals, one of which with the ill-defined acrocentric B chromosome. Mechanisms to justify the suggested hypothesis about this B chromosome origin are discussed in the present study.Cromossomos B são cromossomos extras ao conjunto cromossômico normal, encontrado em diferentes organismos, com destaque para sua presença no grupo de peixes. Callichthys callichthys do alto rio Paraná tem um número diploide de 56 cromossomos (26 m-sm + 30 st-a) para ambos os sexos, com a presença esporádica de um cromossomo B acrocêntrico. Além do mais, um indivíduo apresentou número diploide de 57 cromossomos, com a presença de um cromossomo B acrocêntrico morfologicamente mal definido em todas as células analisadas. O mapeamento físico do DNAr 5S e 18S mostrou múltiplos sítios de DNAr 5S e apenas um par de cromossomos com sítio para o DNAr 18S em C. callichthys, com exceção para dois indivíduos. Estes dois indivíduos apresentaram um terceiro cromossomo portador das RONs (Ag-RONs e 18S rDNA), onde os genes DNAr 5S e 18S são sintênicos, diferindo apenas na posição. A dispersão dos genes DNAr 18S do par de cromossomos principal st-a 25 para um dos cromossomos do par m-sm 4 teria originado dois indivíduos variantes, um dos quais com cromossomo B acrocêntrico mal definido. Mecanismos para justificar a hipótese sugerida sobre a origem deste cromossomo B são discutidos no presente estudo.

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Section: Discussionsupporting

confidence: 78%

B chromosome and NORs polymorphism in Callichthys callichthys (Linnaeus, 1758) (Siluriformes: Callichthyidae) from upper Paraná River, Brazil

et al. 2014

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“…As far as we know, only two fish species bearing B chromosomes have been reported in the Amazon region, i.e., Callichthys callichthys, a Callichthyidae armoured catfish (Porto and Feldberg, 1993), and Metynnis lippincottianus, a Serrasalminae species (Souza et al, 1999). Thus, there seems to be a remarkable bias in the geographic distribution of B chromosomes in Brazil, since most B chromosome records have been reported in southern populations.…”

Section: Resultsmentioning

confidence: 99%

B chromosomes in Amazonian cichlid species

Feldberg

Porto

Alves-Brinn³

et al. 2004

Cytogenet Genome Res

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B chromosomes are reported in three different Amazonian cichlid species. One to three supernumerary microchromosomes were detected in the peacock bass Cichla monoculus (4 out of 28 specimens) and Cichla sp. (4 out of 13 specimens), and pike cichlids Crenicichla reticulata (2 out of 5 specimens), with no similar standard chromosomal morphology. C-banding revealed that B chromosomes are totally heterochromatic. We suggest two scenarios for the origin of these B chromosomes either by chromosomal breakdowns due to mutagenic action of methyl mercury present in the aquatic environment or by interspecific origin due to hybridization events.

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“…The pattern of heterochromatin distribution in Callichthyidae is variable. In general, Callichthys presents reduced C‐bands over centromeric regions (Porto & Feldberg, 1993), while Corydoras tend to bear large centromeric, pericentromeric and terminal heterochromatic blocks in several chromosomes (Shimabukuro‐Dias et al , 2004). Hoplosternum and Megalechis usually present an intermediary amount of heterochromatin, dispersed through centromeric and interstitial chromosomal regions (Shimabukuro‐Dias et al , 2005).…”

Section: Cytogenetic Data In Hoplosternum Littoralementioning

confidence: 99%

Remarkable karyotypic homogeneity in a widespread tropical fish species: Hoplosternum littorale (Siluriformes, Callichthyidae)

Almeida

Affonso

Dias

2012

Journal of Fish Biology

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The first chromosomal data in Hoplosternum littorale from an isolated South American drainage in north-eastern Brazil are presented. All specimens were characterized by a diploid number (2n) of 60 chromosomes divided into three metacentric, one submetacentric and 26 acrocentric pairs; single nucleolar organizer regions (NOR) on the sixth pair; centromeric and interstitial heterochromatin; GC-rich sites on four large acrocentric chromosomes, including the NOR-bearing pair, and 5S ribosomal genes at terminal region on short arms of two acrocentric pairs. These data are invariably similar to previous reports in H. littorale from distant localities throughout South America, which contrasts with the chromosomal diversity of Callichthyidae and reinforces the role of human activities on the dispersal and colonization of this fish.

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IS Callichtys LINNÉ (OSTARIOPHISY, SILURIFORMES, CALLICHTHYIDAE) A MONOTYPIC GENUS?

Cited by 8 publications

References 1 publication

B chromosome and NORs polymorphism in Callichthys callichthys (Linnaeus, 1758) (Siluriformes: Callichthyidae) from upper Paraná River, Brazil

B chromosome and NORs polymorphism in Callichthys callichthys (Linnaeus, 1758) (Siluriformes: Callichthyidae) from upper Paraná River, Brazil

B chromosomes in Amazonian cichlid species

Remarkable karyotypic homogeneity in a widespread tropical fish species: Hoplosternum littorale (Siluriformes, Callichthyidae)

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