Aylton Saturnino Teixeira, Alan Jamieson, José Carlos Paula Raposo
Published: August 27, 2002
Genet. Mol. Res. 1 (3) : 216-226
Cite this Article:
A.Saturnino Teixeira, A. Jamieson, J.Carlos Pau Raposo (2002). Transferrin polymorphism in Central Amazon populations of pescada, Plagioscion squamosissimus. Genet. Mol. Res. 1(3): 216-226.
About the Authors
Aylton Saturnino Teixeira, Alan Jamieson, José Carlos Paula Raposo
Corresponding author: A.S. Teixeira
E-mail: saturn@inpa.gov.br
ABSTRACT
Blood plasma of 253 specimens from eight population samples of the sciaenid fish, pescada (Plagioscion squamosissimus), caught from four sites in the Central Amazon, was tested for molecular variants of transferrin. Starch gel electrophoresis was used to distinguish six species of transferrin molecules; 12 of the 21 theoretically possible genotypes were found. There were highly significant departures from genetic equilibrium in seven of the eight population samples (chi-square (c2) test for Hardy-Weinberg expectations) due to an excess of homozygotes and a corresponding deficiency of heterozygotes. A dendrogram based on UPGMA cluster analysis of genetic distances at the transferrin gene locus, estimated among the population samples and statistical analyses of the distribution of Tf allele frequencies, indicated three genetically discreet sub-populations of P. squamosissimus. The three sub-populations, “Careiro/Iranduba”, “Coari” and “Tefe”, were found to have high frequencies of alleles Tf 2, Tf 4 and Tf 3, respectively. This genetic instability may be attributed to genetically discreet “allopatric stocklets”, which diverged during past isolation.
Blood plasma of 253 specimens from eight population samples of the sciaenid fish, pescada (Plagioscion squamosissimus), caught from four sites in the Central Amazon, was tested for molecular variants of transferrin. Starch gel electrophoresis was used to distinguish six species of transferrin molecules; 12 of the 21 theoretically possible genotypes were found. There were highly significant departures from genetic equilibrium in seven of the eight population samples (chi-square (c2) test for Hardy-Weinberg expectations) due to an excess of homozygotes and a corresponding deficiency of heterozygotes. A dendrogram based on UPGMA cluster analysis of genetic distances at the transferrin gene locus, estimated among the population samples and statistical analyses of the distribution of Tf allele frequencies, indicated three genetically discreet sub-populations of P. squamosissimus. The three sub-populations, “Careiro/Iranduba”, “Coari” and “Tefe”, were found to have high frequencies of alleles Tf 2, Tf 4 and Tf 3, respectively. This genetic instability may be attributed to genetically discreet “allopatric stocklets”, which diverged during past isolation.
Keywords: Transferrin polymorphism, Amazon fish, Pescada, Plagioscion squamosissimus.