Biomedical subjects

Vassily I Grabovsky

Publications and source records attributed to Vassily I Grabovsky.

3 recordsLinked to original sources

PubMed2006

Information about a form (on the dynamic laws of morphogenesis).

How a developing embryo becomes "informed" about its form?" This problem remains obscure and controversial. We argue that the "information about a form" is distributed throughout three main components: the dynamic laws, the parameters and the initial/boundary conditions. In the absence of a dynamic law two other components are "blind", that is, do not contain any unambiguous information. We present a version of a dynamic law of morphogenesis, based upon the presumption of a feedback between passive and active mechanical stresses. We explore several models of shape formation based upon this law and show that, as depending upon the parameters values, they generate a large set of realistic shapes. Genetic and epigenetic basis of the models parameters is discussed.

Animals↗

PubMed2006

Morphomechanics: goals, basic experiments and models.

Morphomechanics is a branch of developmental biology, studying the generation, space-time patterns and morphogenetic role of mechanical stresses (MS) which reside in embryonic tissues. All the morphogenetically active embryonic tissues studied in this respect have been shown to bear substantial mechanical stresses of tension or pressure. MS are indispensable for organized cell movements, expression of a number of developmentally important genes and the very viability of cells. Even a temporary relaxation of MS leads to an increase in the morphological variability and asymmetry of embryonic rudiments. Moreover, MS may be among the decisive links of morphogenetic feedback required for driving forth embryonic development and providing its regular space-time patterns. We hypothesize that one such feedback is based upon the tendency of cells and tissues to hyperrestore (restore with an overshoot) their MS values after any deviations, either artificial or produced by neighboring morphogenetically active tissues. This idea is supported by a number of observations and experiments performed on the tissue and individual cell levels. We describe also the models demonstrating that a number of biologically realistic stationary shapes and propagating waves can be generated by varying the parameters of the hyperrestoration feedback loop. Morphomechanics is an important and rapidly developing branch of developmental and cell biology, being complementary to other approaches.

Animals↗

PubMedDate not supplied

Formative capacities of mechanically stressed networks: developmental and evolutionary implications.

We present a biomechanical model of morphogenesis highlighting the extensive formative capacities of stressed networks with a very simple initial geometry. They consist of a restricted number of kinematically independent elements exerting a pressure to each other and increasing thus the local curvatures. The pressure is applied as a series of periodic impulses and is opposed by a constant quasi-elastic resistance force. Single elements can be also regarded as the half wave-lengths of the undulations determined by the mechanical properties of a given body. All of the model parameters are assumed to be evenly spread throughout a body (no prepatterns are implied). On the other hand, the model parameters can be associated with genetic factors. Thus, our model relates to as yet unsolved problem of genetic regulation of shape formation. We classify the modeled shapes according to their symmetry orders and compare them with the ancient Echinodermata and with Arthropods. Possible evolutionary and developmental implications are discussed.

Biological Evolution↗