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Title: Uso de marcadores citogenéticos clássicos e moleculares para a caracterização de synbranchus spp. (synbranchiformes) da Amazônia central
Authors: Carvalho, Natália Dayane Moura
metadata.dc.contributor.advisor: Gross, Maria Claudia
Keywords: Mussum
Variabilidade cromossômica
Heterocromatina constitutiva
Issue Date: 2-Mar-2011
Publisher: Instituto Nacional de Pesquisa da Amazônia - INPA
metadata.dc.publisher.program: Genética, Conservação e Biologia Evolutiva - GCBEv
metadata.dc.description.resumo: Synbranchidae belongs to the Synbranchiformes order and it is composed by four genus: Macrotema, Ophisternon, Monopterus and Synbranchus. According with the present taxonomic arrangement, Synbranchus comprises three valid species: S. marmoratus Bloch, 1795, S. madeirae Rosen & Rumney, 1972, and S. lampreia Favorito, Zanata & Assumpçao, 2005. However, cytogenetic studies has made evident a variance in the diploid number of specimens of S. marmoratus collected in the south, south-east and center-west of Brasil, presenting 42, 44 and 46 chromosomes and diverse karyotypic formulas. Until nowadays, none cytogenetic characteristics have been registered for the two other valid species. Thereafter this contexture, there have been realized classic cytogenetic analysis (conventional coloration, C Band and NOR) and molecular as well (FISH with rDNA 18S, 5S probers and telomeric sequences) in fourteen individuals of S. madeirae, eight of S. cf. lampreia, one individual of Synbranchus sp.1 and one of Synbranchus sp.2 collected in compatibility at the Catalão lake situated at the confluence of the Negro and Solimões rivers next to Manaus, Amazonas. It was found 2n=46 chromosomes for S. madeirae, being 6m+2st+38a, NF=54, S. cf. lampreia 2n=44 chromosomes, being 6m+2st+36a, NF=52, Synbranchus sp1 2n=42 chromosomes, being 6m+4sm+32a, NF =52 and Synbranchus sp2 2n=42 chromosomes, being 6m+2sm+4st+30a, NF=54. Constitutive heterochromatic presented distributed in the centromeric, interstitial, terminal and proximal and distal of chromosomes majority for the four Synbranchus species. It has been inferred by the nucleolus organizer region (NOR) that simple NOR for S. cf. lampreia and multiple for S. madeirae, Synbranchus sp.1 and Synbranchus sp.2, with interspecific variance as for its distribution, being proved by its impregnation with AgNOR, as much as by r DNA 18S hybridization probe. It has also been proved by FISH with rDNA 5S probe an interstitial marker on pair 7 long arms of S. cf. lampreia and S. madeirae and of pair 10 in Synbranchus sp1. A telomeric probe has evinced marks in all telomeric chromosomes beyond marks in interstitial regions in S. madeirae, S. cf. lampreia and Synbranchus sp.1. It was inferred by the amount of this data that the occurrence of an interspecific karyotypic variability on Synbranchus genus, including heterochromatinization or heterochromatin addition, appearance of Robertsonian and non-Robertsonian rearrangements in chromosomic evolution of this group. Meanwhile, we believe that the evolutive tendency most likely for this group is from an ancestor with 2n = 48 chromosomes with reduction of the diploid number.
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