Caracterização citogenômica em Hoplias malabaricus (Bloch, 1794) provenientes de rios de águas brancas, águas claras e águas pretas da Bacia Amazônica
Fecha
2012-05-11Autor
http://lattes.cnpq.br/4992470263606781
SANTOS, Fabíola Araújo dos
Metadatos
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The Amazon basin has a high diversity of fish species, distributed around
different aquatic environments. Among the many factors that determine such
Amazonian environments we can highlight the water colors of the rivers, which are
classified in white water, clear water and black water rivers. The present study aimed to
analyze specimens of Hoplias malabaricus in these different environments by means of
classical (C and NOR banding) and molecular cytogenetic markers Cromomycin A3
and FISH using DNAr5S e 18S genes and transposable element Rex 3 probes. We
analyzed 60 individuals collected from the Amazon River (white water), Negro River
(black water) and Tapajos River (clear water). All the specimens showed a diploid
number of 2n = 40 chromosomes with a karyotype formulae 20M +20SM in both the
sexes. Small blocks of heterochromatin in the centromeric regions of all chromosomes
and the distal regions of some pairs were detected. Staining with silver nitrate in the
three environments ranged from four sites of NOR, being observed demarcation
bitelomeric just in the population of the black water. The rich regions in GC varied from
three to six marked chromosomes. Regarding to the location of the gene DNAr5S, it
was mapped in the pairs 14 and 15. Already the gene 18S presented six sites in the
populations of the white and clear water and three sites marked in the population of the
black water. The chromosomal location of the Rex 3 probe showed three clearly distinct
patterns. In a sample from white water, this marker was detected in the centromeres of
all chromosomes and distal few pairs, showing a similar pattern to that obtained by
banding C. While in samples from the clear water environments Rex 3 marker was
detected in almost all regions of telomeric and centromeric chromosomes of some, the
black water was found in only a few chromosome pairs. The cytogenetic differences
found in H. malabaricus in three Amazonian environments studied may be related to a
pattern of adaptation of this organism in these environments.
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