Induced diploid gynogenesis and polyploidy in the ornamental (koi) carp Cyprinus carpio L.
The results of a series of experiments conducted in our laboratory on the ornamental common carp (koi), aimed at optimizing heat-shock chromosome-set manipulation procedures, are described. The timing of heat-shock initiation was expressed in the relative unit of embryological age (τ0) in order to standardize this parameter, the absolute time for heat-shock initiation being calculated from duration of one τ0 at two different pre-treatment water temperatures. Heat shocks were applied within the periods of 0.05–0.60 τ0 and 1.20–2.20 τ0 which, respectively, cover the successive phases of the 2nd meiotic division and the 1st cleavage. The highest production of diploid gynogenetic offspring was observed when heat shocks were initiated at 0.15–0.25 τ0 and at 1.5 τ0, after insemination, corresponding to anaphase of meiosis-II, and metaphase of the 1st cleavage, respectively. Similar results were obtained irrespective of the different pre-treatment water temperatures, thus confirming the possibility of standardizing heat-shock timing by τ0.
Induced diploid gynogenesis and polyploidy in ornamental (koi) carp, Cyprinus carpio L. 2. Timing of heat shock during the first cleavage
Abstract Experiments on timing of heat shock during the first cleavage in order to optimize induced diploidization of the chromosome set were conducted on ornamental (koi) carp, Cyprinus carpio L. The effect of heat shock on embryo survival and ploidy level was monitored in gynogenetic offspring and regular ones. Dimensionless measure of embryological age τ 0 was used to express the time of heat shock application. The heat shock was initiated within the limits of 0.6–3.0 τ 0 (0.9–2.0 τ 0 in most experiments) after insemination. Incubation temperature prior to treatment was either 25°C or 20°C. Water temperature of heat shock was 39.3–40.5°C, and duration 2–3 min, in different experiments. Embryo survival is characterized by alternating “sensitive” and “non-sensitive” periods with lowest survival when heat shock initiation corresponds to 1.6–1.8 τ 0 . The highest frequency of 2n mitotic gynogenetic embryos (up to 15% relative to total number of inseminated eggs) was observed when heat shock was initiated at 1.5–1.6 τ 0 .
Diploidization of gynogenetically activated salmonid eggs using hydrostatic pressure
Abstract Optimum conditions for hydrostatic pressure treatment for duplication of the chromosome set were studied in gynogenetically activated salmonid eggs of three species, rainbow trout (Salmo gairdneri), cherry salmon (Oncorhynchus masou) and chum salmon (O. keta). One hundred percent of the eggs were diploidized when they were subjected to hydrostatic pressure (650–700 kg/cm2 for a duration of 6–10 min) 5 min after insemination. Normal diploid embryos were encountered when eggs were treated between 5 and 40 or 270 and 330 min after insemination.