Seven transferrin variants (A,B,C,D,E,F, and G) have been found in carp sera (Cyprinus carpio L.). Genetic analysis involves five variants and agrees with the hypothesis of simple codominant autosomal inheritance at one transferrin (Tf) locus in spite of the fact that the carp is a tetraploid in relation to other species of the same family. Carp populations from three regions were studied which differed in gene frequencies. Individual populations were in Hardy-Weinberg equilibrium. The polymorphism of carp transferrins can be used for the identification of offspring of single parent pairs, stocked in one pond. Transferrins have been isolated and characterized. Homozygous phenotypes comprised four iron-binding components differing in electrophoretic mobility. This heterogeneity is not caused by sialic acid, which is absent. Amino acid composition, content of hexoses (1 mole/mole of protein) and hexosamines (1 mole/mole of protein), molecualr weight (70,000), and the isoelectric point (5.0) have been determined. No N-terminal amino acid could be detected.
Isoenzyme patterns and the polymorphism of lactate dehydrogenase (LDH) were investigated in 3 fish species of family Cyprinidae, i.e. tench (Tinca tinca), crucian carp (Carasshs carassins) and carp (Cyprinus carpio). The isoenzyme patterns were tissue and species specific. In crucian carp subunits with different electrophoretic mobility are present, which are genetically controlled from the B1, BZ, A*, A? and C loci, while the set of loci in carp is B1, B?, A, C1 and C2 and in tench B, A, C. The locus B of LDH in tench, the locus B2 in crucian carp, and the loci Bl, C1 and Cc in carp are polymorphic and have two different alleles in each case. The polymorphism did not affect the total LDH activity in the tissues. All the populations investigated were in Hardy-Weinberg equilibrium. The genetic control of the polymorphism in B1 and C1 loci in carp was proved by test matings. The polymorphism in B loci tested in erythrocytes may be utilized as genetic markers in the fish breeding.
Incidental and/or uncontrolled hybridization between silver carp (Hypophthalmichthys molitrix) and bighead (Aristichthys nobilis) represents a serious problem in Czechoslovak aquaculture. This fact affects fitness traits very negatively in successive generations of hybrids. To solve this problem, 1076 individuals in a total of both H. molitrix. A. nobilis, and their hybrids in 12 groups from six rearing facilities were analysed. Twelve protein systems representing 21 presumptive loci were studied to analyse the electrophoretic patterns of their products using horizontal starch gel electrophoresis of blood and tissue extracts. Both species displayed identical electrophoretic patterns in MYO‐I*, LDH‐A*, LDH‐B*, sMDH‐1*, sIDHP‐3*, GPI‐1*, and CK‐I* loci. For a reliable differentiation of both species products of the following nine loci are applicable ALB*, PA*, TF, sMDH‐2*, SOD*, NDH*, MYO‐IF, MYO‐III*, and CK‐2*. In addition, some polymorphic variants in slDHP‐1*, sIDHP‐2*, LDH‐C*, EST‐II*, and GPI‐2* loci are of use as auxillary markers while the other variants are common to both species. A high level of gene introgression was evident through hybridization between both species. All groups declared previously as ‘H. molifrix’ were actually confirmed biochemically to be H. molitrix. However, all groups declared as ‘A. nobilis’ were proved to be a mixture of A. nobilis and its hybrids of different level with H. molitrix. This suggests it is impossible to distinguish between A. nobilis and hybrids using their external morphology only.
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