GENETIC-VARIATION IN DIFFERENT VARIETIES OF SIAMESE FIGHTING FISH USING ISOELECTRIC-FOCUSING OF SARCOPLASMIC PROTEINS

Sarcoplasmic proteins of four colour varieties of Siamese fighting fis h, Betta splendens Regan, were analysed by isoelectric focusing (IEF). Genetic polymorphisms were detected in six loci having isoelectric po ints: 4.92-5.00 (Sp-1), 5.33-5.48 (Sp-2), 5.90 (Sp-3), 6.31-6.35 (Sp-4 ), 6.58-6.70 (Sp-5) and 6.90 (Sp-6). For the Sp-1, Sp-2, Sp-4 and Sp-5 loci, there were two codominant alleles. At Sp-3 and Sp-6, one allele was dominant and the other null. Individuals within each locus were c lassified into phenotypes A, AB and B. Only homozygotes were found at Sp-2. Allele frequencies were calculated for each locus and tested for accordance with the Hardy-Weinberg equilibrium. Observed values for e ach phenotype at Sp-1, Sp-3, Sp-4, Sp-5 and Sp-6 agreed well with the expected ones. At Sp-2, genotypic frequencies for each variety deviate d markedly (p < 0.01) from the equilibrium. When tested for homogeneit y, no significant differences (p greater than or equal to 0.95) in gen e frequencies were found among the varieties except at Sp-2. Band shar ing index (BSI), computed using the BIO-GENE v5.04 program, revealed h igh intravariety genetic similarities (0.701-0.740) and slightly above -average intervariety values (0.550-0.583). In this study, we estimate d the levels of genetic variability in B. splendens, and proposed a ge netic model for each polymorphic locus.