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A A Neĭfakh

Publications and source records attributed to A A Neĭfakh.

At least 37 records · Page 2Linked to original sources
PubMed1974

[Nuclear function during early development of remote fish hybrids].

The participation of paternal genome was studied in the development of remote hybrids obtained as a result of artificial insemination of the loach (Misgurnus fossilis) eggs by the sperm of aquarial Cyprinids (Brachydanio rerio, Danio malabaricus, Barbus tetrazona, Razbora heteromorpha, Carassius auratus) and Cobitids (Acanthophtalmus kuhlii). The hybrids obtained differed at the stage of hatching both from each other and from the loach by some morphological features. To study the function of heterologous nuclei, haploid nucleocytoplasmic hybrids were obtained by means of chromosome inactivation in the loach eggs by heavy doses of X-rays. The participation of paternal genome in development was estimated by comparison of the curves of viability of diploid and haploid hybrids with those of diploid, haploid and "anuclear" loach embryos. Patterns of mortality of embryos and larvae in each hybrid combination (percentage, stage) suggest the functioning of paternal genome already at the early stages of development. The activity of hybrid and heterologous nuclei was also estimated by the onset and the intensity of morphogenetic function which was determined by the time of embryonic death following nuclear inactivation at different stages. The onset of nuclear function in all hybrids coinsides with that in the loach, except B. rerio in which it occurs somewhat earlier. The data obtained prove the participation of paternal genes in development and maintenance of viability of embryos at all developmental stages beginning from the early ones (blastula).

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PubMedDate not supplied

[Cytophotometric and biochemical research on the amount of DNA in the nuclei of loach embryos injected with low-molecular RNA].

The cell cycle structure in the cells of loach embryos at the early blastula stage (5 h of development at 21 degrees) is markedly altered under the influence of injection of homologous low molecular weight nuclear RNA and, as a result, the number of cells in G2-phase. The DNA amount in the embryo increases by 20%. At the midblastula stage (7 h) no increase in the number of cells in G2-phase was found.

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PubMedDate not supplied

[The functioning of mammalian mitochondria injected into fish embryos].

The possibility of mammalian mitochondria functioning in fish embryos has been studied. Suspension of mitochondria isolated from the mouse fibroblast B-82/cap (chloramphenicol-resistant) and B-82 (chloramphenicol sensitive) cell cultures, were injected into the fertilized loach eggs. These embryos with an artificially increased number of mouse mitochondria developed and lived till the larval stages. Activity of cytochrome oxidase in these embryos was 1.5-2 times that in the control several hours after the injection, decreased during development and reached the control level by the gastrula stage. If these embryos with artificially increased number of mouse mitochondria were incubated in presence of chloramphenicol, only embryos that contained mitochondria from chloramphenicol-resistant cells survived, thus suggesting that the injected mitochondria do not degrade but are preserved and function in the cytoplasm of developing loach embryos.

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PubMedDate not supplied

[The nature of the dependence of the rate of development on temperature determines the greatest efficiency of metabolism at optimal temperatures].

Metabolism intensity and development rate have different pattern of dependence on temperature. Oxygen intake and several other metabolic processes bear an exponential relationship to temperature. The pattern of this relationship is similar in different poikilothermal species. On the contrary, the relationship between the rate of development and temperature is species-specific and more complex. Hence, the curves obtained by plotting oxygen intake per developmental stage against temperature resemble parabola and the minimum values of oxygen intake correspond to optimal temperatures. Such a correspondence is almost solely determined by parameters of the relationship between the rate of development and temperature. Therefore, the efficiency of metabolism does not determine the range of optimal temperatures. It is suggested that adaptive alterations of this range during evolution proceed via changes of the parameters of relationship between the rate of development and temperature dependence. Relatively small number of mutations is required to produce such changes.

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PubMedDate not supplied

[Foreign DNA in developing embryos of the loach Misgurnus Fossilis L].

The fate of pAT153 DNA microinjected into the embryos of loach was examined. At the earliest stages of development (2 h) the high molecular weight transgenome consisting of pAT153 sequences is formed. The transgenome replicates intensively during the course of early development (until the blastula--early gastrula stages), but later the replication slows down which results in the elimination of the transgenome from the majority of embryos at more advanced stages. The analyses of the transgenome structure with the help of restriction endonucleases have shown that, after microinjection of linear DNA, the high molecular weight transgenome is formed by stochastic ligation of the sticky ends of injected molecules. Our data suggest that the transgenome formation from circular or supercoil DNA occurs after its linearization by host endonuclease.

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PubMedDate not supplied

[Does DNA alone determine the development of the organism? (the information aspect of the problem)].

Two closely related controversial problems are discussed: whether the developmental processes can be reduced to the synthesis of polypeptides encoded in DNA, and whether the information in DNA is equivalent to that in the adult organism. Critically considered are the ideas that DNA is only responsible for the protein synthesis, whereas morphogenesis proceeds independently and according to epigenetic regularities of its own. It is stated that development is the realization of genetic information in which more elementary (molecular) processes unambiguously determine a more complex cellular level which in its turn determines morphogenesis of tissues and organs. Various mechanisms of the appearance of new information in the course of development are considered. The statement is made that new information concerns only some individual characters of the organism, whereas most of information that determines the process of development and the structure of the adult organism is created in the course of evolution, is stored in DNA and inherited.

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