Limits...
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 F1 hybrids “pintachara” (A,B) and “cachapinta” (C,D) and F2 hybrids (E,F) after silver nitrate staining. Panels (A), (C) and (E) show cells with two Ag-NORs and panels (B), (D) and (F) show cells with only one Ag-NOR. Arrows indicate the NOR-bearing chromosomes. Scale bar = 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3313517&req=5

f4-gmb-35-1-57: Metaphases of the F1 hybrids “pintachara” (A,B) and “cachapinta” (C,D) and F2 hybrids (E,F) after silver nitrate staining. Panels (A), (C) and (E) show cells with two Ag-NORs and panels (B), (D) and (F) show cells with only one Ag-NOR. Arrows indicate the NOR-bearing chromosomes. Scale bar = 10 μm.

Mentions: In the parental species, NORs were observed on the short arms of subtelocentric pair 18 (Figure 1A,C) which, in addition to the size polymorphism observed in some metaphases, showed positive C-banding (Figure 1B,D). In the F1, F2 and backcross hybrids, NORs were located on the short arm of two subtelocentric chromosomes of the same size that were polymorphic in some cells (Figures 2A,C and 3A,C) and totally heterochromatic (Figures 2B,D and 3B,D). In addition, silver nitrate staining revealed variations in the distribution of NORs in F1 and F2 hybrids, in which cells with only one active NOR and others with two active NORs were identified (Figure 4 and Table 1).


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 F1 hybrids “pintachara” (A,B) and “cachapinta” (C,D) and F2 hybrids (E,F) after silver nitrate staining. Panels (A), (C) and (E) show cells with two Ag-NORs and panels (B), (D) and (F) show cells with only one Ag-NOR. Arrows indicate the NOR-bearing chromosomes. Scale bar = 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

f4-gmb-35-1-57: Metaphases of the F1 hybrids “pintachara” (A,B) and “cachapinta” (C,D) and F2 hybrids (E,F) after silver nitrate staining. Panels (A), (C) and (E) show cells with two Ag-NORs and panels (B), (D) and (F) show cells with only one Ag-NOR. Arrows indicate the NOR-bearing chromosomes. Scale bar = 10 μm.
Mentions: In the parental species, NORs were observed on the short arms of subtelocentric pair 18 (Figure 1A,C) which, in addition to the size polymorphism observed in some metaphases, showed positive C-banding (Figure 1B,D). In the F1, F2 and backcross hybrids, NORs were located on the short arm of two subtelocentric chromosomes of the same size that were polymorphic in some cells (Figures 2A,C and 3A,C) and totally heterochromatic (Figures 2B,D and 3B,D). In addition, silver nitrate staining revealed variations in the distribution of NORs in F1 and F2 hybrids, in which cells with only one active NOR and others with two active NORs were identified (Figure 4 and Table 1).

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.