Chromosome doubling by pressure treatments for tetraploidy and mitotic gynogenesis in rainbow trout, Oncorhynchus mykiss (Walbaum): re-examination and improvements |
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| Authors: | L FOISIL D CHOURROUT |
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| Institution: | Laboratoire de Génétique des Poissons, INRA, Jouy-en-Josas, France |
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| Abstract: | Abstract. Pressure treatment has up to now been the best method to inhibit the disjunction of chromosomes during the first mitosis of salmonid embryos. We have determined the optimum conditions to maximize the yield of tetraploid embryos (fertilization with normal sperm), and the yield of diploid mitotic gynogens (insemination with irradiated sperm). This study has provided two major results: the replacement of gamma-rays by ultraviolet rays, in order to inactivate the sperm for gynogenesis, markedly increases the yield of viable mitotic gynogens, probably because they reduce the risk of any'toxic'partial paternal transmission. The optimal pressure levels for mitotic inhibition are higher than those we had indicated in an earlier study. We interpret this discrepancy as an error of calibration of the pressure apparatus which had been used. |
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