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Biomedical subjects

L A Martynov

Publications and source records attributed to L A Martynov.

17 recordsLinked to original sources
PubMed1976

[Number of whorls and umbel rays in Acetabularia].

It was found in the proposed model of morphogenesis of Acetabularia that the number of whorls N (as well as the number of umbel rays) depends on the degree of mechanical instability of the deforming cell wall (the greater is instability, the higher is the value N). The genetic control of final morphogenetic processes can be realized by setting definite physical conditions and properties. The theoretical estimates of N carried out for different cases agree fairly well with the experimental data obtained.

Cell Count↗
PubMedDate not supplied

[Mechanical deformations of bioconstructions during different stages of morphogenesis].

The stress-deformation regularities of the body behaviour are taken as principal pattern formation factors in bioconstructions: mutually compressed cap rays of Acetabularia and contiguous tissue layers (the model). With the growth of rays or layers mechanical tensions which are initiated in them increase. If no morphogenetic loss of shape stability is resulted, an alternative algorithm of natural complication of their initial pattern is finally realized and ruptures, shifts and other deformations are formed in some weakened elements of the constructions. Among rigid stable parameters of biomaterials and geometric parameters of bioconstructions only the latter prove to be the determining ones in feasibility criterion of this or that extreme case of pattern formation (with the loss of stability or fractures). Restrictions imposed to the values of possible deformations are conditioned in case of the loss of pattern stability by geometric parameter, in case of fractures--by the strength parameters.

Acetabularia↗
PubMedDate not supplied

[Increase in the rigidity of bioconstruction material during the process of morphogenesis].

Structural rigidity of the material of cell wall in the cylindrical part of Acetabularia apex resulting from the fibrillar structure and of the cell wall properties and deformations realized during anisotropy, were studied. Values of Jung's moduli and Poisson's coefficient of the growing wall were obtained. It was shown that anisotropy of the material featured inner geometrical rigidity of the bioconstruction which restricted the deformations, and in case of structural instability predetermined their morphogenetic switching.

Acetabularia↗
PubMedDate not supplied

[Growth, elastic and inelastic deformations in morphogenetic processes].

On the basis of rheological equation of standard body (as a physical state equation) the stress relaxation or deformation delay (the creep) accompanying the growth of adjacent layers (the model) or the growth of acetabularia apex are studied. It is shown that both initial geometrical characteristics of elastic and viscoelastic deformations determine final morphogenetic complication of bioconstructions, while time characteristics of deformations--the viscosity parameters of growth. Additional morphogenetic switching of development occurs during abrupt (of the phase type) changes in materials states resulting, among other things, from metabolic catastrophs. And vice versa, "catastrophic" changes in the shape of the morphogenetic system affects the course of metabolic processes.

Acetabularia↗
PubMedDate not supplied

[Mechanical and chemical patterns in the completion of isolated cell division].

Bicellular complex of a divided oocyte of the mollusc Lymnea stagnalis is chosen as a "testing machine" for studying mechanical and biochemical properties of the membranes of interblastomere wall. The membrane material is described by a standard rheological body. Rheological and kinetic problems are considered. Their solution allows an experimental solution of elastic, viscose and relaxation constants and chemical-mechanical parameter of the balance of the membrane synthesis and its deformations. A relationship (of the logistic type) between the growth of the wall area and time is found.

Acetabularia↗
PubMedDate not supplied

[Morphogenetic loss of shape stability in biological constructions].

The stress-deformation regularities are taken as basic pattern formation factors in biological macrosystems. Mechanical stresses occuring in the growing biological objects give rise to large deformations involving the loss of shape stability with the morphogenetical complication (fold production). Both theory and experiment show that the smaller is construction rigidity of macrosystem (Acetabularia mediterranea and Drosophila melanogaster) the larger is the number of the embryonal folds.

Acetabularia↗
PubMedDate not supplied

[Deformation and morphogenesis of Acetabularia cell membrane. I. Relation of deformation to genetic and geometric factors].

Relationships between the changes of geometric shape, volume and deformations of the apical growth part of acetabularia cell are studied. Jung module E approximately 25 kg/cm2, viscosity coefficient of the apex cell theta 4 - 10(4) kg-sec/cm2 and intracellular pressure P approximately 1 kg/cm2 are measured. Cell shape formation according to Waddington is concerned with simple physical factors which are under the genetic control. It is shown that uneven deformations with the loss of shape stability bring about periodic cell complications.

Acetabularia↗
PubMedDate not supplied

[Deformation and morphogenesis of Acetabularia cell membrane. II. Local mechanisms of regulating viscoelastic deformations].

Relationships between growth velocities of some parts of Acetabularia cell, ratio between the thickness of the cell membrane and apex diameter (its constructive rigidity), intracellular pressure and viscose-elastic deformations are used for physical substantiation of Waddington's concepts concerned with the existence and important search of local morphogenetic mechanisms. Their realization in a strongly deformated regions of Acetabularia cell membrane is shown. The relationship between viscosity, synthesis of the material and dimensions of region and intracellular pressure is found.

Acetabularia↗