Occurrence of Cytotypes and Variability of AgNORs in a Population of &lt;i&gt;Bryconamericus&lt;/i&gt; aff. &lt;i&gt;iheringii&lt;/i&gt; (Characidae)

Eberhardt, Gabriel Néia; Silva, Laura Lahr Lourenço da; Santos, Angélica Rossotti dos; Dias, Ana Lúcia

doi:10.1508/cytologia.77.507

Cited by 3 publications

(2 citation statements)

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“…From Eberhardt et al (2012) until the present study, the collections in Três Bocas Stream occurred at different times for approximately five years and during that period the number of cytotypes increased. It is worth noting that instead of documenting individuals with cytotypes already described, researchers have documented new specimens representing other cytotypes, suggesting that this point of Três Bocas Stream is transitional for B. aff.…”

Section: Discussionmentioning

confidence: 79%

Karyotypic diversity in a population of Bryconamericus aff. iheringii (Characidae)

Silva¹,

Giuliano-Caetano²,

Dias³

2014

Genet. Mol. Res.

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ABSTRACT. Bryconamericus comprises 56 species distributed into three groups, on the basis of the position and shape of the maxillary teeth: B. exodon, B. microcephalus and B. iheringii groups. Few cytogenetic data are available for this genus, but the diploid number of 52 chromosomes is quite common, although the karyotypic variability is extensive. This study aimed to characterize a population of B. aff. iheringii and thus contribute more cytogenetic information and better understanding of the structure and karyotypic evolution of this genus. We found 6 cytotypes with different NOR patterns: cytotype I showed a karyotype formula of 12m+10sm+16st+14a (FN = 90) and single NORs; cytotype II with 18m+14sm+10st+10a (FN = 94) and cytotype III with 20m+18sm+4st+10a (FN = 94), showing both single and multiple NORs; cytotype IV with 20m+14sm+12st+6a (NF = 98), cytotype V with 22m+18sm+8st+4a (FN = 100) and cytotype VI with 18m+24sm+6st+4a (FN = 100), all with multiple NORs. Cytotype I is the most different in relation to FN and NOR pattern, and can be regarded as belonging to another species of the genus Bryconamericus, living in sympatry in Três Bocas Stream. The remaining cytotypes may have been generated by crosses between them and by pericentric inversions. Meiotic cells were also analyzed and showed that despite the high karyotypic variability, chromosome pairing occurred normally. The great variability found in B. aff. iheringii may be related to a high degree of polymorphism; nevertheless, the possibility of occurrence of more than one species in this location is not ruled out, demonstrating the need for conservation of the Três Bocas Stream.

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Section: Discussionmentioning

confidence: 79%

Karyotypic diversity in a population of Bryconamericus aff. iheringii (Characidae)

Silva¹,

Giuliano-Caetano²,

Dias³

2014

Genet. Mol. Res.

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“…Cytogenetic studies in trans-Andean Bryconamericus species evidenced the maintenance of the diploid number of 52 chromosomes, with inter and intraspecific divergences regarding the karyotype formula and the fundamental number (FN) (Paintner-Marques et al, 2002a, 2002bCapistano et al, 2008;Portela-Castro et al, 2008;among others). Likewise, other cytogenetic characters were shown to be variable, such as the distribution of heterochromatin and the number and location of the nucleolar organizer regions (NORs) (Eberhardt et al, 2012;Santos et al, 2012Santos et al, , 2017Silva et al, 2014), with variation even among individuals of the same population. In relation to 5S rDNA ribosomal genes, the data are restricted to only four species, revealing simple cistrons in B. cf.…”

Section: E190057[2]mentioning

confidence: 99%

Cytogenetic markers as tools in delimiting species of the highly diverse Neotropical fish Bryconamericus (Characiformes: Characidae)

et al. 2019

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Bryconamericus is a highly diverse group of characid fishes, being cytogenetic a valuable tool for the delimitation of species. Bryconamericus aff. iheringii (Upper Uruguay/Lower Paraná), B. coeruleus (Upper Paraná), B. cf. ecai e B. cf. eigenmanni (Upper Uruguay) were studied cytogenetically, and presented 2n=52 chromosomes, with interpopulational/interspecific variation of karyotype and fundamental number. Heterochromatin was evidenced in pericentromeric, telomeric and interstitial regions, and it was shown to be an important cytogenetic marker. Single nucleolar organizing regions (NORs) were found in B. cf. eigenmanni, B. cf. ecai and B. aff. iheringii (Lower Paraná), and multiple in B. aff. iheringii (Upper Uruguay) and B. coeruleus, with occurrence of two patterns for the first species, and three for the second. The 5S/18S rDNA-FISH confirmed the location of the NORs and showed single 5S rDNA cistrons only in B. aff. iheringii (Lower Paraná), evidencing the dispersion of both genes, often co-located, in the karyotype of the others species. The data of this work contribute for the delimitation of the species of the genus. Co-localization of ribosomal genes may represent a plesiomorphic condition for the group, and their dispersion suggest the occurrence of duplication, pseudogeneization and transposition events mediated by mobile genetic elements.

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Chromosomal Mapping of Repetitive DNA Sequences in the Genus Bryconamericus (Characidae) and DNA Barcoding to Differentiate Populations

et al. 2017

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The mapping of repetitive DNA sites by fluorescence in situ hybridization has been widely used for karyotype studies in different species of fish, especially when dealing with related species or even genera presenting high chromosome variability. This study analyzed three populations of Bryconamericus, with diploid number preserved, but with different karyotype formulae. Bryconamericus ecai, from the Forquetinha river/RS, presented three new cytotypes, increasing the number of karyotype forms to seven in this population. Other two populations of Bryconamericus sp. from the Vermelho stream/PR and Cambuta river/PR exhibited interpopulation variation. The chromosome mapping of rDNA sites revealed unique markings among the three populations, showing inter- and intrapopulation variability located in the terminal region. The molecular analysis using DNA barcoding complementing the cytogenetic analysis also showed differentiation among the three populations. The U2 small nuclear DNA repetitive sequence exhibited conserved features, being located in the interstitial region of a single chromosome pair. This is the first report on its occurrence in the genus Bryconamericus. Data obtained revealed a karyotype variability already assigned to the genus, along with polymorphism of ribosomal sites, demonstrating that this group of fish can be undergoing a divergent evolutionary process, constituting a substantive model for studies of chromosomal evolution.

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Occurrence of Cytotypes and Variability of AgNORs in a Population of <i>Bryconamericus</i> aff. <i>iheringii</i> (Characidae)

Cited by 3 publications

References 14 publications

Karyotypic diversity in a population of Bryconamericus aff. iheringii (Characidae)

Karyotypic diversity in a population of Bryconamericus aff. iheringii (Characidae)

Cytogenetic markers as tools in delimiting species of the highly diverse Neotropical fish Bryconamericus (Characiformes: Characidae)

Chromosomal Mapping of Repetitive DNA Sequences in the Genus Bryconamericus (Characidae) and DNA Barcoding to Differentiate Populations

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