Polymorphism and heterogeneity of transferrins in some species of the fish family Cyprinidae

Abstract

Summary In fish of the family Cyprinidae extensive polymorphism and heterogeneity of serum transferrins were found. Ten variants of transferrins were detected in barbel, 9 in dace and bleak, 7 in chub and bream, 6 in rudd, 5 in roach, white bream, silver carp, big head and crucian carp, 3 in tench, and 2 variants in nase, ide and goldfish. All the variants observed bound radioactive iron. The phenotype patterns indicated a simple genetic determination, by a set of codominant alleles at one locus, and this even in tetraploid species. Transferrins of some species were partly isolated. The transferrins of all 22 species analysed were heterogeneous and homozygous pheno‐types had 1 to 6 zones of various intensities, binding 59 Fe. In barbel both single‐zone and two‐zone variants were present and transferrins of roach had variable heterogeneity. Sialic acid was found only in transferrins of silver carp, big head and in the two‐zone variants of barbel. The occurrence of phenotypes with single and double zones of transferrins in barbel indicates the possibility of genetic determination of the inability of single‐zone variants to bind sialic acid.