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Cytogenetic characterization of F1, F2 and backcross hybrids of the Neotropical catfish species Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Pimelodidae, Siluriformes).

do Prado FD, Nunes TL, Senhorini JA, Bortolozzi J, Foresti F, Porto-Foresti F - Genet. Mol. Biol. (2012)

Bottom Line: The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes.Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens.Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista "Júlio de Mesquita Filho", Bauru, SP, Brazil.

ABSTRACT
The cytogenetic characteristics of Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum and their F1, F2 and backcross hybrids were assessed by using chromosome banding techniques. The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes. Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens. Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals. For parental and hybrid lineages, 18S ribosomal clusters corresponding to NORs and 5S ribosomal genes were identified in distinct pairs of chromosomes. The striking conservation in the chromosomal macrostructure of the parental species may account for the fertility of their F1 hybrids. Similarly, the lack of marked alterations in the chromosomal structure of the F1 hybrids could account for the maintenance of these features in post-F1 lineages.

No MeSH data available.


Metaphases of the parental species P. corruscans (A) and P. reticulatum (B), F1 hybrids “pintachara” (C) and “cachapinta” (D), F2 hybrids (E) and backcross hybrids (F) after FISH with 18S and 5S rDNA probes. Arrows indicate the chromosomes bearing 18S (green) and 5S (red) rDNA. Scale bar = 10 μm.
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f5-gmb-35-1-57: Metaphases of the parental species P. corruscans (A) and P. reticulatum (B), F1 hybrids “pintachara” (C) and “cachapinta” (D), F2 hybrids (E) and backcross hybrids (F) after FISH with 18S and 5S rDNA probes. Arrows indicate the chromosomes bearing 18S (green) and 5S (red) rDNA. Scale bar = 10 μm.

Mentions: FISH confirmed the location of the 18S ribosomal genes in two subtelocentric chromosomes corresponding to the NOR-bearing chromosomes (Figure 5) in all of the samples studied. The 5S ribosomal genes were detected in the pericentromeric area of the short arm of a subtelocentric pair in P. corruscans and P. reticulatum. In F1 and post-F1 hybrids these genes occurred in the same area of two subtelocentric chromosomes of similar size and morphology (Figure 5).


Cytogenetic characterization of F1, F2 and backcross hybrids of the Neotropical catfish species Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Pimelodidae, Siluriformes).

do Prado FD, Nunes TL, Senhorini JA, Bortolozzi J, Foresti F, Porto-Foresti F - Genet. Mol. Biol. (2012)

Metaphases of the parental species P. corruscans (A) and P. reticulatum (B), F1 hybrids “pintachara” (C) and “cachapinta” (D), F2 hybrids (E) and backcross hybrids (F) after FISH with 18S and 5S rDNA probes. Arrows indicate the chromosomes bearing 18S (green) and 5S (red) rDNA. Scale bar = 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3313517&req=5

f5-gmb-35-1-57: Metaphases of the parental species P. corruscans (A) and P. reticulatum (B), F1 hybrids “pintachara” (C) and “cachapinta” (D), F2 hybrids (E) and backcross hybrids (F) after FISH with 18S and 5S rDNA probes. Arrows indicate the chromosomes bearing 18S (green) and 5S (red) rDNA. Scale bar = 10 μm.
Mentions: FISH confirmed the location of the 18S ribosomal genes in two subtelocentric chromosomes corresponding to the NOR-bearing chromosomes (Figure 5) in all of the samples studied. The 5S ribosomal genes were detected in the pericentromeric area of the short arm of a subtelocentric pair in P. corruscans and P. reticulatum. In F1 and post-F1 hybrids these genes occurred in the same area of two subtelocentric chromosomes of similar size and morphology (Figure 5).

Bottom Line: The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes.Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens.Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista "Júlio de Mesquita Filho", Bauru, SP, Brazil.

ABSTRACT
The cytogenetic characteristics of Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum and their F1, F2 and backcross hybrids were assessed by using chromosome banding techniques. The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes. Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens. Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals. For parental and hybrid lineages, 18S ribosomal clusters corresponding to NORs and 5S ribosomal genes were identified in distinct pairs of chromosomes. The striking conservation in the chromosomal macrostructure of the parental species may account for the fertility of their F1 hybrids. Similarly, the lack of marked alterations in the chromosomal structure of the F1 hybrids could account for the maintenance of these features in post-F1 lineages.

No MeSH data available.