GYNOGENESIS IN STURGEON FISH OBTAINED BY MEANS OF IRRADIATION (in Russian)
In the present preliminary work the possibility has been shown of producing diploid gynogenesis in the sturgeon, sterlet and beluga. It has also been shown that in hybrid crossings after irradiation of sperm with a high dose (100 kr) the progeny copies entirely the characters of the maternal species. At the same time, the diploid (apparently normal) gynogenetic larvae obtained are distinguished by their low viability. According to this material, the viability in experiments on gynogenesis is reduced in other species of fish also (loach, carp), but not so markedly as in sturgeons. In the loach, for example, in the case of gynogenesis (when the sperm are irradiated with a dose of 100 kr) the mortality of the developing roe amounts to a total of 8-20 percent; in the carp, 32-50 percent, whereas in sturgeons it is 85-95 percent. Thereby, the apparently normal larvae which hatch out in the experiments with the loach and carp (gynogenetic diploids) are apparently more viable; in the carp, for example, it is possible to bring their cultivation to the age of two years (1/sup +/), three years (2/sup +/) and probably even older. The question arises, what are the causes of such a reduction of the viability of gynogenetic diploids? First of all, in using the method of deactivating the nucleus of the sperm cell by irradiation it was seen cytologically that the head of the sperm cell, as in normal development, is converted into a male pronucleus and only then, in metaphase, does it form a pyknotic body which occupies a central position in the spindle of the first cleavage division. Such a position of the sperm cell nucleus can introduce mechanical interference into the division of female chromosomes, without mentioning the fact that the presence of a pyknotic nucleus can create different biochemical conditions in the cytoplasm, distorting the normal course of seginentation and further development. The fact that the presence of the deactivated nucleus is not immaterial for the developing embryo, is evidenced by the somewhat increased percentage of anaphases and telophases with chromosome bridges in the cells of the caudal epithelium of one-day larvae in the irradiation experiments compared with the controls. Thus, in the controls the percentage of cells with bridges in the sterlet amounts to M/sub k/ = 2.00 percent plus or minus 0.50; for larvae from the irradiation experiments, M/sub 100kr/ = 9.47 percent plus or minus 0.78 (Diff plus or minus m/diff/= 7.47 percent plus or minus 0.92); approximately the same relations are observed in the sturgeon larvae M/sub k/ =2.79 plus or minus 0.38 M/sub 100kr/ == 8.50 percent plus or minus 1.48 (Diff plus or minus m/sub diff/= 5.71 percent plus or minus 1.52). Similar data were obtained for the loach and the carp, where embryonic mitoses were recorded at the gastrula stage. Other causes for the reduction in the viability of the diploid gynogenetic individuals are identified. (auth)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-037100
- OSTI ID:
- 4647646
- Journal Information:
- Radiobiologiya (U.S.S.R.) For English translation see Radiobiology (Engl. Transl.), Journal Name: Radiobiologiya (U.S.S.R.) For English translation see Radiobiology (Engl. Transl.) Vol. Vol: 3; ISSN RADOA
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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