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A T Mikhaĭlov

Publications and source records attributed to A T Mikhaĭlov.

At least 19 recordsLinked to original sources
PubMed1982

[Effect of heterogeneous inducers on the ectoderm of the early gastrula in Rana temporaria in vitro. IV. The inductive effect of embryonic tissue extracts after ribonuclease and proteinase treatment].

An attempt was undertaken to determine the chemical nature of the neuralizing and lens-inducing effect of the retina and brain extracts from 7-8 day old chick embryos. These extracts were treated with immobilized enzymes (RNAse, proteinase K) and the effect of treatment was then estimated in the organ cultures (reacting tissue - early gastrula ectoderm). The effect of the enzymes was studied in different experimental variants which allowed to exclude the effect of the own proteases and temperature on the inducing activity of the extracts under study. The neuralizing activity of the retinal extract was shown to preserve after its treatment with RNAse but to be almost fully lost (or decrease) after proteolytic hydrolysis. Proteinase suppressed as well completely the lens-inducing effect of the extract from the chick embryo brain. A conclusion is drawn that the inducing activity of the extracts under study is due to proteins, rather than to RNA.

Animals↗
PubMed1980

[Cross-reacting antigens of the mammalian ovular zona pellucida].

Antigens of zona pellucida (ZP) of different mammalian species, including the man, were studied by means of various immunochemical methods. The analysis was carried out using rabbit antisera to the pig, mouse, guenon and Java macaque eggs. After immunoadsorption (by blood serum and tissue extracts) these anti-ZP-sera reacted with water-insoluble ZP components only (in immunofluorescence). The adsorbed anti-ZP-sera were specific not only to homologous ZP, but also to ZP of other mammalian species. The spectrum of antigens of the ape ZP was most closely related to that of human ZP. The pig eggs contained antigens common with the human ZP as well. The antiserum to the mouse ZP did not react with ZP of man, ape, pig, cow, rabbit and other species under study. The blood of sterile women contained the antibodies reacting (in immunofluorescence) with ZP of mouse, pig, guinea pig, sheep and man (very weakly). The data obtained suggest the complexity of antigenic mosaic of the mammalian ZP including both "cross-reacting" (common) antigens and species specific ones.

Animals↗
PubMed1979

[Immunohistochemical identification of specific antigens in stained and balsam-embedded eye lens sections].

Localization of specific proteins at preliminary stained with azan and embedded in balsam sections of amphibian eye lens (Rana temporaria, Xenopus laevis) was studied by indirect immunofluorescence. The analysis was performed on the lens of intact animals as well as on lens induced in amphibia gastrula ectoderm in vitro. To remove balsam the lens sections were successively washed by xylene, ethanol and saline (pH 7.1). Then they were treated according to the general principles of immunohistochemical analysis. Specific antigens have been thus shown to be detectable at lens sections which had been kept in balsam for over a year. The immunofluorescent reaction to lens proteins was negative at more prolonged storage of the sections (2--3 years).

Animals↗
PubMed1978

[Experimental and biochemical aspects of crystalline lens induction during embryogenesis].

The lens induction is a two-step process and involves morphogenetic influences from the archencepalic endoderm and optic vesicle. One can suggest that the lens induction is primed by specific proteins which are synthesized and secreted by the optic vesicle cells. The proteins-inductors appear to penetrate in the cells and, while interacting (directly or via the cytoplasm) with the nuclei, "programme" the ectodermal cells towards the lens differentiation. The contact interactions and extracellular matrix are of substantial, but not crucial value for the lens induction. The synthesis of specific proteins (crystallins) is to be considered as the most objective criterion of lens differentiation. In vertebrates, there is a lag-period between the moment of lens induction and synthesis of crystallins which is the most long-term in amphibians. The chick embryos constitute an exception and the synthesis of crystallin mRNA occurs in them a few hours after the lens induction. The developing retina loses its capacity to induce lens but stimulates the processes of fiber formation and synthesis of crystallins. A factor was found in the definitive lens epithelium which may be considered as a possible regulator of lens differentiation. On the basis of experiments with heterogenous and native lens inductors, a suggestion is put forward to the effect that the activity of inducing substances is determined by a definite determinant group of the molecule, rather than by the whole molecule.

Animals↗