THE POLYMORPHIC PROTEINS AND THEIR GENETIC-CONTROL IN THE SILVER CARP

Specimens of silver carp (Tb), verified as to their species purity, were studied for the polymorphism of their liver lactate dehydrogenase (LDH C), cytoplasmic NADP+ dependent isocitrate dehydrogenase (s-IDH 2), glucosophosphate isomerase (GPI 2) and the transferrin variants (Tf). Two LDH C variants were identified and it was demonstrated by parent analysis that they are genetically controlled from one locus by two alleles, Ldh C(a) and LDH C(b). The frequency of allele Ldh C(a) ranged from 0.422 to 0.000 in the different populations. Polymorphism was also found and demonstrated by parent analysis in the s-Idh locus. The two variants under study are genetically controlled by alleles s-Idh 2a and s-Idh 2b. However, the frequency of the s-Idh 2a allele, determined until now just in one population, is comparatively very low (0.027). The frequency of the polymorphic allele of locus Gpi 2 (Gpi 2b) was also low, ranging from 0.063 to 0.000 in the different populations. Parent analysis also confirmed the genetic control of the polymorphic variants of transferrin (Tf(b) and Tf(c)) and variant 2aa of glucosophosphate isomerase. As the identified polymorphic variants of Tb do not overlap with the Tp (big head) variants, they can be used as genetic markers not only in the breeding of the silver carp but also in distinguishing it from the Tp variant and the hybrids of Tb with Tp.