Production of Heterozygous and Homozygous Clones of Common Carp (cyprinus Carpio L.): Evidence from Dna Fingerprinting and Mixed Leukocyte Reaction

The production of two heterozygous and one homozygous clones of the Israeli Dor-70 line of common carp (Cyprinus carpio L.) was tested using DNA fingerprinting (DFP) and mixed leukocyte reaction (MLR) analysis. The clones were obtained in large-scale production from mitotic gynogenetic females and males (sex-inversed). MLR analysis was used to examine major histocompatibility complex (MHC) antigens in individuals. DFP provided evidence concerning identity in the whole genome. Both methods showed that individuals within a progeny were identical, confirming genetic uniformity within each clone and showing that no paternal DNA was transmitted during mitotic and meiotic gynogenesis. The results indicated that uniformity of DFP in progeny of the homozygous clone is obtained only when the mother is fully homozygous, and in the heterozygous clone only if both parents are fully homozygous. The results of both methods provide evidence, though indirect, that the mitotic gynogenetic parents of these fish (mother of the homozygous clone, mother and father of the heterozygous clones) were fully homozygous. obtained by induced gynogenesis. The aims of this study were to confirm the genetic uniformity among progeny and to prove that no paternal DNA was transmitted during gynogenetic reproduction. Materials and Methods Creation of clones. The fish were bred at the Fish and Aquaculture Research Station, Dor. Preliminary experiments started in 1992, and the two heterozygous and one homozygous clones were obtained in 1994. Standard methods of fish rearing were used. Samples from these clones were taken to Bar Ilan University, Tel Aviv, where they were maintained as described by Rosenberg-Wiser and Avtalion (1982). The experimental fish were produced from the Dor-70 common carp, the most important commercial line of Israeli common carp (Wohlfarth et al., 1980). The sequence for producing heterozygous and homozygous clones is presented in Fig. 1. The parents of the three clones were gynogenetic females (F1) obtained from regular common carp females (P) by induced diploid mitotic gynogenesis (Cherfas et al., 1993). Due to the cytological peculiarities of mitotic induced gynogenesis, the F1 generation (mitotic gynogenetic progeny) was expected to segregate for maternal genes, but each mitogynogenetic individual was expected to be fully homozygous. Further, the gynogenetic generation should be all-female due to female XX homogamety. 91 Production of heterozygous and homozygous clones of common carp Fig. 1. Production of heterozygous and homozygous clones of the Dor-70 carp line. Mitotic gynogenesis (1992) Meiotic gynogenesis Regular mating Mitogynogen (all-female) offspring F1 MT treatment for sex reversal and rearing to sexual maturity Rearing to sexual maturity Females of the Dor-70 carp line P Sex-reversed mitogynogen males (1993) Mitogynogen females (1994) X F2 Dor-70 heterozygous clones (1994) Dor-70 F2 homozygous clone (1994)