Colocalization of repetitive DNAs and silencing of major rRNA genes. A case report of the fish &lt;i&gt;Astyanax janeiroensis&lt;/i&gt;

Vicari, Marcelo Ricardo; Artoni, Roberto Ferreira; Moreira‐Filho, Orlando; Bertollo, L.A.C.

doi:10.1159/000151318

Cited by 74 publications

(72 citation statements)

References 75 publications

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“…In the genus Hypostomus, variations in the heterochromatic pattern among different species are commonly observed, as we found here. Heterochromatic segments that overlap with or are adjacent to ribosomal sites are frequent in Neotropical fish, as we observed with H. ancistroides, H. nigromaculatus and H. tapijara, a fact that, probably, enabled the dispersion of NOR sites over the genome (Moreira-Filho et al, 1984;Vicari et al, 2008).…”

Section: Discussionsupporting

confidence: 66%

Chromosomal diversity in Hypostomus (Siluriformes, Loricariidae) with emphasis on physical mapping of 18S and 5S rDNA sites

Traldi¹,

Blanco²,

Vicari³

et al. 2013

Genet. Mol. Res.

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ABSTRACT. We examined chromosomes of three species of the genus Hypostomus, in order to contribute to the understanding of the karyotype evolution of this group. Specimens of H. ancistroides and H. nigromaculatus displayed differences in karyotype formulas, distribution and location of heterochromatin and nucleolus organizer regions when compared to other populations of the same species. We made the first cytogenetic characterization of H. tapijara, an endemic species in the Ribeira de Iguape River. These specimens had 2n = 66 chromosomes, while H. ancistroides showed 2n = 68 and H. nigromaculatus 2n = 76 chromosomes. Physical mapping of 18S and 5S rDNA sites of the three species showed simple, multiple and syntenic clusters. Synteny of ribosomal sites was found in H. ancistroides and H. tapijara, and an interspersed pattern between these sites in all chromosomes bearing the synteny was observed. We conclude that the genus Hypostomus has a high chromosome complexity that is accompanied by great morphological variation. It is evident that this group comprises an interesting model for understanding the chromosome evolution of Neotropical ichthyofauna.

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Section: Discussionsupporting

confidence: 66%

Chromosomal diversity in Hypostomus (Siluriformes, Loricariidae) with emphasis on physical mapping of 18S and 5S rDNA sites

Traldi¹,

Blanco²,

Vicari³

et al. 2013

Genet. Mol. Res.

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“…The number and location of the 18S rDNA sites in Astyanax is considered variable and multiple (Néo et al, 2000;Ferro et al, 2001;Mantovani et al, 2005 andVicari et al, 2008a), dispersed by karyotypes mainly through transposition mechanisms (Fernandes & Martins-Santos, 2006;Vicari et al, 2008b). The two populations from Ribeirão Grande analyzed in the present study corroborated with the condition of multiple 18S rDNA sites found in other Astyanax.…”

Section: Discussionsupporting

confidence: 85%

Evidence of incipient speciation in Astyanax scabripinnis species complex (Teleostei: Characidae)

et al. 2014

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Two populations of the Astyanax scabripinnis complex, isolated by a waterfall with over 100 meters depth and inhabiting different altitudes of the same river (1850 m a.s.l. and 662 m a.s.l.) were compared in reproductive data, geometric morphometry, tooth morphology, anal-fin rays counts, and karyotype, in order to test the hypothesis of speciation between the two populations. The results in the geometric morphometry analysis showed differences between the populations. Discriminant function analysis (DFA) and canonical variance analysis revealed sexual dimorphism. Secondary sexual characters, such as hooks in the anal fin rays of the males are absent in the lower altitude population. Both populations had the same macro karyotype structure, except for the absence of B chromosomes in the lower altitude population. The fluorescence in situ hybridization showed differences for both markers (18S rDNA and 5S rDNA), and reproductive data suggests pre-zygotic reproductive isolation among the two populations. The data showed the absence of gene flow, indicating that an incipient speciation process has occurred, which leads the two populations to follow independent evolutionary pathways.Duas populações do complexo Astyanax scabripinnis isoladas por uma queda d´água de mais de 100 metros de altura e localizadas em diferentes altitudes do mesmo rio (662 m e 1850 m a.s.l.) foram comparadas através de dados de reprodução, cariótipo, morfometria geométrica, morfologia dentária, e número de raios da nadadeira anal, de modo a testar a hipótese de especiação entre as duas populações. Os resultados de morfometria geométrica mostraram diferenças entre as populações. A análise da função discriminante (DFA) e a análise de variância canônica (CVA) demonstraram a presença de dimorfismo sexual. Caracteres sexuais secundários, como ganchos em raios da nadadeira anal dos machos, estão ausentes na população de menor altitude. Ambas as populações têm a mesma macro estrutura cariotípica, exceto pela ausência de cromossomos B na população de menor altitude. A hibridação in situ mostrou diferenças para ambos os marcadores (rDNA 18S e rDNA 5S), e os dados de reprodução sugerem isolamento reprodutivo pré-zigótico entre as duas populações. Os dados mostram ausência de fluxo gênico, indicando que ocorreu um processo de especiação incipiente, o que leva as duas populações seguirem vias evolutivas independentes.

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“…In fact, divergences in the satellite DNA sequences have been considered as a tool to establish the evolutionary relationships among species or even populations. For instance, chromosome-specific satellite DNA in fish has been used as reliable cytogenetic marker to elucidate the phylogenetic relationships among distinct taxa (Herrán et al 2001;Saito et al 2007), to cytotaxonomic inferences of species complexes (Mantovani et al 2004;Kantek et al 2009;Vicari et al 2008), or even to determine the origin of supernumerary chromosomes.…”

Section: Discussionmentioning

confidence: 99%

Similarity of heterochromatic regions in the stingless bees (Hymenoptera: Meliponini) revealed by chromosome painting

et al. 2014

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Most Meliponini share a distinctive pattern of heterochromatin distribution in relation to other bees. In general, they present one euchromatic and one heterochromatic chromosome arm, a feature explained by minimum interaction theory, which involved centric fissions followed by heterochromatin addition. In this work, two Meliponini with a distinct pattern of heterochromatin distribution, Tetragonisca fiebrigi and Melipona rufiventris, were analyzed using chromosomal microdissection of the heterochromatin region followed by FISH (fluorescent in situ hybridization). Hybridization revealed FISH signals equivalent to location of the isolated fragment that were widespread over heterochromatic portions of other chromosomes. This result showed that the heterochromatic sequences were very similar among chromosomes in the same species. Cross-hybridization of each probe in M. rufiventris and T. fiebrigi yielded no signals, revealing that both species presented differentiated and non-homologous heterochromatin sequences.

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Colocalization of repetitive DNAs and silencing of major rRNA genes. A case report of the fish <i>Astyanax janeiroensis</i>

Cited by 74 publications

References 75 publications

Chromosomal diversity in Hypostomus (Siluriformes, Loricariidae) with emphasis on physical mapping of 18S and 5S rDNA sites

Chromosomal diversity in Hypostomus (Siluriformes, Loricariidae) with emphasis on physical mapping of 18S and 5S rDNA sites

Evidence of incipient speciation in Astyanax scabripinnis species complex (Teleostei: Characidae)

Similarity of heterochromatic regions in the stingless bees (Hymenoptera: Meliponini) revealed by chromosome painting

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