[Discrete probability of a model for information provision on early embryonic development]. / Diskretnaia veroiatnostaia model' informatsionnogo obespecheniia rannego émbrional'nogo razvitiia.

A percolation model of the diffuse redistribution of morphogenetic information in early regulative development is analyzed. It is demonstrated that the statistical average values of cell connectedness remaining below the percolation threshold of the spatial redistribution of developmental determinants do not provide for the formation of cell structures of the necessary size. The average number of cell interactions should exceed the percolation threshold, and, therefore, the carriers of morphogenetic information in early development can move over distances comparable with the size of the entire embryo. The assumption concerning the percolation mechanism of cell death is used as a basis for estimating the statistical average value of cell connectedness at which the predicted number of cells theoretically isolated from the flow of signal molecules corresponds to the observed frequencies of dying embryonic cells. The estimated average number of cell interactions significantly exceeds the threshold of information resource percolation in the embryonic space and agrees with estimations of other authors, based on direct observations. The probable role of the diffusion front, or percolation cluster shell, in the regionalization of embryonic structures differing in their prospective values is discussed. It is shown that the duration of the communicative period, along with the statistical average number of channels providing for the intercellular transfer of signal molecules by diffusion, is a parameter controlling the processes of determination of embryonic structures.

[Relation of cyclic and noncyclic electron transport in Rhodospirillum rubrum chromatophores. I. Experimental study of the kinetic characteristics of dark reduction of P870 with different donor concentrations in the medium]. / Sootnoshenie tsiklicheskogo i netsiklicheskogo élektronnogo transporta v khromatoforakh rhodospirillum rubrum. I. Eksperimental'noe issledovanie kineticheskikh kharakteristik temnovogo vosstanovleniia P870 pri razlichnykh kontzentratsiiakh donora v srede.

The kinetics of the dark recovery of photo-oxidized bacteriochlorophyll P870 was studied as a function of the intensity and duration of actinic light illumination at different concentrations of a donor in the medium. From the comparison of the experimental data with the results of mathematical modelling of the processes under investigation [1] it is concluded that electron transport is triggered for another pathway, whenever the concentration of the donor in the medium attains a certain critical level.

[Theoretical study of the kinetics of dark reduction of photochemically oxidized bacteriochlorophyll in the reaction center of Rhodospirillum rubrum chromatophores]. / Teoreticheskoe issledovanie kinetiki temnovogo vosstanovleniia fotokhimicheski okislennogo bakteriokhlofofilla reaktionnogo tsentra v khromatoforakh Rhodospirillum rubrum

It is shown from the results of theoretical study that the scheme involving two successive interacting components of the pool of secondary acceptors shows the biexponential character of the kinetics of dark reduction of the pigment of P870 observed in the experiment. The velocity constants of the electron transport reactions considered are evaluated.