Optimization of shock parameters in inducing mitotic gynogenesis in the carp Cyprinus carpio L.

The relative effects of heat-shock parameters on the induction of first-cleavage suppression of common carp (Cyprinus carpio L.) eggs were examined. Eggs of females with scattered scales were fertilized with sperm that had been irradiated with gamma-ray cobalt-60. Fertilized eggs were exposed to heat shock at different temperatures (39, 40, 41 °C) for periods of 1–3 min at 0.5-min intervals, initiated at 41, 44, or 47 min post fertilization in a factorial design. The use of three treatment factors made it possible to analyze the main effects and all possible combinations of the three factors. The highest percentage of mitotic gynogenetic diploids (mitotic-G2n) (up to 10.6% survival at the feeding larva stage relative to the total number of inseminated eggs) was obtained from the groups treated at 40 °C for 2 min at 44 min post fertilization (ambient temperature 21 °C). Optimum duration was observed to be 2.5–3 min at 39 °C and 1–1.5 min at 41 °C. The embryos were developed under hatchery condition, while larvae were reared in a flow-through system with natural feeding. Isozyme and scale pattern analysis performed on putative mitotic-G2n individuals both proved that their genome is of maternal origin.