Genetic Study on the Biochemical Polymorphism in Red Sea Bream

Abstract

Thirteen isozymes of various organs and sarcoplasmic protein of muscle of the red sea bream, Pagrus major (Temminck et Schlegel), were assayed by the horizontal starch-gel electro-phoresis in order to detect the genetic variation which would be useful as the maker in subpopulation and breeding studies. Polymorphism was found in various isozyme systems such as ADH, esterase, α-GDH, GOT, ICD, LDH, MDH, 6-PGD, PGM, PHI, and SDH. Based on the polymorphic banding pattern of each isozyme, two alleles were presumed in the respective loci, such as α-Gdh, Got-III, Icd, Ldh-B, Pgm, and Sdh, three alleles in Adh, Got-II, Mdh, 6-Pgd, and Phi-II loci, and 8 alleles in Est locus. There were no significant differences between observed proportion of phenotypes and their H_ARDY-W_EINBERG expectation in most of the loci examined. The proportion of polymorphic loci was 34.3%, a relatively high value in comparison with other marine fishes. The proportion of occurrence of Heterozygous loci per individual was 6.6%, a comparatively similar rate to other marine fishes. The growth rate of wild red sea bream at 1 year old was independent of polymorphism in each enzyme system. It was concluded that the ADH, EST, 6-PGD, PGM, and SDH isozymes would be useful as characteristics of subpopulation and as genetic markers of the family and brother-sister in breeding studies.