MAIN GOALS AND TASKS

Developmental biology and evolution of living systems

The head of Laboratory
O.F. Chernova

Main subjects of research: revelation of structural adaptations of the systems of organs and tissues of vertebrates to environmental conditions.

Research tasks: 1) to show a wide polymorphism in the structure of the systems of organs at different levels of their organization; 2) to analyze an adaptive nature of the structure of the systems of organs, using morphological functional analysis; 3) on the basis of the methods of comparative morphology, to reveal analogical, homological, species-specific and organo-specific structures and the ways of their formation and transition in the phylogeny of vertebrate animals (convergence, divergence, parallel development etc.); 4) based on the experimental methods, to determine recovery potentials of the tissues and organs, subjected to negative influences of different factors of environment.

The problem of adaptation of animals to environmental conditions remains actual, especially in conditions of dynamically changing environment (the changes of ecology, pollution, strengthening of anthropogenic load, degradation of landscapes etc.). Understanding of adaptive mechanisms, regulating the structure of the systems of organs and their recovery potential will allow not only to determine the plasticity of the species and ecological forms, but to understand the directivity of evolutionary process and, at the final analysis, to prognose the reserve of species viability. A particular position in such investigations belongs to experimental method of the study of such phenomena as recovery of muscles, brain, and liver after different unfavorable influences and diseases (including those of interstellar flight, after the cerebral stroke, laser exposure, immobilization stress etc.). Adaptive reactions of tissue systems of organism in comparative range of vertebrates in physiological parameters and under the influence of different abiotic and anthropogenic factors of environment are under study: physical factors (swimming, physical activities), gravitation factors (rotation in centrifuge, experiments on supporting unloading of muscles), radiation factors (irradiation of the muscles by ionizing radiation with the following exposure to the rays of the laser of low intensity), man-caused factors (ecologically unfavorable territories - the water area of the Volgo-Caspian basin, Oksko-Donskoe interfluve).

Most important achievements of the Lab for the latest 10 years

The perineal gland of an adult male of the common mole – Talpa europaea (staining for fat with sudan black B)

The paranasal gland of an adult male of the common pipistrelle – Pipistrellus pipistrellus (hematoxylin-eosin staining)

The galdular area of the ventral nasal surface of the common shrew – Sorex araneus (staining for fat with sudan III)

It was determined that topography, structure and function of cutaneous glands of mammals, as derivatives of integument , reflected the patterns of evolution and adaptive radiation of taxa, serving as criteria of taxonomic status and adaptation of the species and living forms to environment. Principally important, as a whole, for morphology of integument and zoology a question about the existence of the fourth independent type of cunaneous glands in mammals (excluding sebaceous glands, apocrine and eccrine sweat glands) was solved - the hepatoid glands, the data about which were false or absent at all in scientific literature of the recent 50 years. The criteria of their identification were developed, and also exocrine type of secretion, protein or lipo-protein character of the secret, independence as glandular type, organospecificity and signal character of the secret smell were determined. As a result of revision of early inhouse studies, critical analysis of literary data and special study made by us, hepatoid glands were revealed in 29 species of mammals from different taxa. The results obtained change essentially many ideas and views about the glandular apparatus of the skin, its evolution and chemical communication in these species.

For the first time in world zoology systematically, according to entire plan the fine structure of hair in representatives of 18 orders of Mammalia was studied (322 species). Wide polymorphism and adaptive importance of hair structure and also its diagnostic meaning were revealed. A concept about parallel formation of hair and vibrissa in phylogeny of mammals was suggested. Vibrissa differs markedly from the hair in its structure and, possibly, has originated from mechanoreceptors of ancient forms (cotylosaurus), developing only in the branch, represented by recent species of marsupials and placental mammals. In the branch represented by recent species of Monotremata, they are absent at retention of electro- and mechanoreceptors. Hair originated in parallel in the both branches from keratinizing epidermis. Its evolution was followed by formation of homoiothermy and went independently from vibrissa evolution. Wide and intensive adaptive radiation led to extremely expressed polymorphism of hair, in many features similar in various taxa (morphological parallel development). Spines were formed as a result of heterochronies (temporal difference in formation) of various generations of hair.

It was revealed that the degree of reduction of natal down feathers of birds denoted not relatively longstanding origin of the taxa, but stability of the presence or progress in the loss of this, obviously, atavistic feather plumage in representatives of different taxonomic groups. Abundance of down plumage was obviously not a direct adaptation to nestling conditions, since nude and weakly feathered nestlings were present in representatives of openly and closed nestling species of the same families both in inhabitants of tropics and high latitudes. The data about embryonic plumage of birds, besides using in systematics, allowed formation the ideas about the ways of feather evolution. A hypothesis has been developed, in accordance to which one of the reasons of evolutionary breakthrough of avian theropod dinosaurs had become an attaining of homoiothermy, provided by heat-insulating properties of feathered skin as well. At that, filamentous structures facilitated heat-insulation, and feather-like ones advantaged mainly adaptation to aerial and aquatic environment. Morphological diversity and peculiarities of development of feather structures in ontogenesis of recent bird species have been retaining the traits of long-term evolution of cutaneous appendages until now.

A concept of morphological convergence in evolutionary development of guard hair, spines and quills of mammals and feathers of birds, the appearances of which represent aromorphosises, the great evolutionary events, drastically risen the level of organization of mammals and birds, provided them with heat-insulation and a possibility to displace reptiles in conditions of climate coldness. On the basis of hair polymorphism (more than 300 species were studied) and feathers (80 species) it was determined that fine structure of the basic structures (cuticle, cortex, and medullae) of the hair and feather was similar in these phylogenetically separated classes. Convergence in hair and feather structure was soluble at the functional basis: execution of similar functions (heat-insulation one in this case) determined creation of the structures with similar design in coordination with other organs and mechanical limitations. The basic direction in evolution both of hair and feather, facilitating the execution of their heat-insulation function lied in formation of air-bearing structures.

General patterns and peculiarities of embryonic development and structure of stomach chambers in phylogenetically close species of the subfamily Caprinae (Bovidae, Artiodactyla) were revealed at all levels of structural organization in connection with their food specialization including the species with a shared areal (saiga, Kalmyk sheep). Ultra-structure of epithelium surface of the stomach chambers served as an index of its usage by symbionts as an ecological niche. Macro- and microstructure of the stomach showed the peculiarities of feeding and the character of endosymbiocenose in any of studied species (saiga, sheep, goat). The degree of domestication led to weakening of the digestive type (in domestic sheep), and the degree of expressiveness of the digestive type in wild species was stipulated by specifics of their feeding. For the first time on the basis of functional morphology of stomach chambers, classification according to feeding types of closely related species of Caprinae (highly selective, partially selective and unselective) was presented, allowing to understand the degree of nutritional competition between species with overlapping areals.

General patterns of development of the organ of hearing and equilibrium were determined in mammals in pre- and postnatal ontogenesis. Comparative-embryological description of the peripheral part of the auditory system of terrestrial, semi-aquatic and aquatic mammals was given with the use of unique collection on cetaceans and pinnipeds. The structural organization of this part was studied in detail, the phases of formation of the outer, middle and inner ear were determined in phylogenetically close species, but with different ecological specialization and for the forms phylogenetically remote but with similar ecology. It was shown that the main morphological functional adaptations in evolution of the organ of hearing were the adaptations, directed to optimization of auditory sensitivity in various environments.

Morphological adaptation of cold-blooded animals was revealed: at low temperatures they released an excess of iron ions, appearing from destroyed erythrocytes, by the way of ion transformation in Kupffer cells of liver into the pigment melanin. In summer period in fishes and amphibians this process went in Kupffer cells with formation of ferritin and hemosiderin.

For the first time the effectiveness of intermittent action of hyper-gravitation was shown as a counter-measure, preventing or decreasing development of atrophic processes, appearing in the muscles of posterior legs in animals as a result of the loss of supporting load (in the model experiments imitating zero gravity conditions). Reliable increase in the number of stem cells in muscular fibrils, and also the lowering of the number of fibrils with intense degeneration of myofibrils was seen under preliminary action of hyper-gravitation.

Laser irradiation of low intensity (LILI) influences the processes of secondary histogenesis of skeleton muscular tissue, going in different conditions (local irradiation of the muscles and total irradiation of the organism). A stimulating effect of LILI on regeneration of irradiated skeleton muscles was shown: acceleration of inflammation reaction, resorption of decay products in the wound, increase in proliferative activity of muscular elements, normalization of the process of collagen formation. Positive influence of LILI on reparative processes in the muscle was determined by the dose and regime of treatment. Thus, with the help of LILI it is possible to influence the viability of allogenic muscular tissue, both under homotransplantation of entire muscle and under implantation of grinded homomuscle into the area of trauma of irradiated and non-irradiated damaged skeleton muscles.

Systemic study of muscular tissue of bony fishes, inhabiting the water area of the Volgo-Caspian basin, allowed to determine various ways of development of destructive processes in the white and red skeletal muscles of fishes and to give corresponding explanations to this phenomenon. For the first time it was shown that pathology of the muscular system of fishes included also the development of degenerative changes in corresponding parts of their nervous system, affecting both motor and sensory innervation of the muscles.

Undertaken citogenetic studies of the Rook populations, inhabiting different zones of Tula region (Oksko-Donskoe interfluve) showed that ionizing radiation and chemical pollutants made a substantial impact into mutagenic process. In the Rook populations from the regions with the greatest degree of anthropogenic load, an increased level of chromosomal injuries was seen in the cells of eye cornea. In the cornea cells of rooks in the zone with maximal degree of pollution, 81.5 times more mutations appeared compared to non-polluted region.