MOST IMPORTANT RESULTS

The objects of research

The main theme of the Laboratory is the study of specifics of chemical reception and communication of animals in aquatic and aerial environment in ecology field. The works of laboratory are included into research work of the Institute on ethology. Many new peculiarities in amphibian behavior were revealed. A complex system of data about behavioral intra- and interrelations of larvae in four species of tailless amphibians was obtained. It was established that these larvae perceived chemical stimuli - excretions of various aquatic animals and usually avoided them. Especially intensely they avoided the stimuli from potentially dangerous predators, of both vertebrate and invertebrate animals. Behavioral interactions of tadpoles and several species of predators were investigated with the purpose to study the presence and details of 'chemical defense' of amphibian larvae, the secretions of cutaneous glands of which contained various substances. The characteristics of avoidance behavior to alarm pheromone from damaged skin of conspecifics in tadpoles of common toad were defined. It was determined that main freshwater predators test seized tadpoles by means of taste. The effectiveness of chemical defense of the tadpoles of common toad is dependent on peculiarities of manipulation of the predator with the prey and the strategy of its prey-catching behavior. This part of works is tightly connected with the monitoring of amphibian and fish populations carried by us in the region of the special nature reserve "Ozero Glubokoe" (Deep Lake). The useless of breeding of most amphibian species and two species of crucian carps in small waterbodies colonized by rotan, an introduced predatory fish of Amur fauna, was proved. Special expeditions and database composed in the laboratory showed continuing broadening of the rotan areal. Unavoidable invasion of the fish, which changes significantly the biocenoses, into Western Europe has been predicted. New data about orientation of the young amphibians in water and after their going out to land at metamorphosis were obtained. It was revealed that final product of nitrogen metabolism of aquatic animals, ammonia, in larvae of amphibians could play a role of avoided pheromone of disturbance. Larval amphibian adaptations revealed are important for deepening of knowledge about freshwater ecosystems organization as important model of general ecology, and for development of the measures of conservation of these animals, the number of which is decreasing all over the world. Species-specificity of behavioral reactions in larvae of tailless amphibians to natural amino acids was shown and a prevailing decrease in sensitivity to these substances at the late phases of larval development was established. Long-term studies in chemosensory sensitivity in various tritons during their aquatic phase of life revealed a wide range of effective chemical stimuli and specified the ideas about the functions of chemosensory systems in organization of behavior in these animals.

The use of an original method, allowing determination of distinguishing possibility of compared stimuli without elaboration of preliminary differentiation, revealed a positive correlation between the grouping of amino acids as chemosensory perceived stimuli by fishes and the charge of the molecules of these substances.

A plasticity of olfactory sensitivity formation in ontogeny of some rodents was revealed. A phenomenon of induced sensitivity to olfactory stimuli in rodents was found and its genericity and validity both for separate substances (biologically important and unimportant) and compound mixtures (animal excretions) was experimentally proved. It was shown that induced sensitivity to olfactory stimuli was realized at receptors level and followed by the changes of nervous connections with the primary sensory center; it possessed highly specific character and didn't influence the sensitivity to the substances, structurally not bound to the substance-stimulator. An inbred line of mice with specific anosmia to the pheromone of boar - androstenon was produced. Polygenic character of this feature was demonstrated. A locus on the 13th chromosome participating in the control of sensitivity to androstenon was determined. With the use of immunohistochemistry methods, a specific spatial pattern of activation of vomerionasal organ in males of three mice species was revealed under perception of the smell of receptive female's urine.

A pheromone of reduction of the size of litter and of change in the sex ratio towards the males under the influence of predator odor exposition (domestic cat urine) was described at the early phases of pregnancy in common rat and house mouse. The effect was underlain by implantation abnormality. At that, a drastic fall of progesterone level in the plasma of female blood was marked. Seasonal changes of sensitivity to predator smell were described. The vomeronasal system played the key role in realization of the effect. A line of rats with increased sensitivity to predator odor was produced, and this line can be used for the basic and applied research. The active components were extracted from cat's urine.

Under theoretical analysis of the principles of work of olfactory analyzer, the algorithms of solution of the task of cognition of a single odorant substance in the mixture with other unknown substances or cognition of the individual animal odor in the mixture with the odors of other individuals were developed and the estimates of probability of error depended upon the number of mixture components and the number of olfactory sensors were obtained. Stochastic properties of electric reactions of olfactory sensillas of the males of the silkworm Bombyx mori to stimulation with the single molecules of bombical (a component of female's pheromone) were studied. The density of specific membrane receptors and constants of dissociation of the complex of receptor-pheromone molecule were estimated. The proofs for existence of two parallel chains of transduction in olfactory cells of silkworms were obtained. Electrophysiological and morphological study of trichoid sensilla on the antenna of males of Siberian silkworm (Dendrolimus superans sibiricus) was undertaken. The composition of female's pheromone was specified. A new component of female pheromone of pine lappet moth, propionate Z5, E7-12-Pr was determined, which played a role either of sexual attractant or inhibitor of males' attraction of a closely related species.

Neurological and morphological studies important for development of evolutionary neurobiology and scientific basis of general and space medicine were undertaken. As a result of joint research together with Research Center of the Institute for Medicine and Biology and American Authority on Aeronautics (NASA), the directions for development of the methods for enrichment of the sensory environment of spacemen were determined for their training to accelerative forces appearing at landing of a spacecraft. The Laboratory took part in inter-institutional complex studies on the stem cells of mammals, including a man. Together with two other Institutes of the RAS, a prospect of stem and progenitor cells transplantation was revealed, and also for the cells, undergone transfection by genes of neurotrophic factors, into the nervous system and eyes of test animals with experimental degenerative abnormalities. The results are very important for development of new, more effective methods of patients' treatment with neurodegenerative diseases of brain and eyes. The studies directed to development of new methods of treatment of patients with ischemic stroke are undertaken. It is shown that reparative processes taking place in the brain after ischemia, including proliferation of neuronal stem cells, were connected with activation during paradoxal (fast) sleep. Under complex study of the mechanisms of regulation of the sleep-wakefulness cycle in mammals, the substances highly effective for initiation and maintenance of sleep were revealed which differed profitably from the existent "somnifacients". The results are important for creation of principally new psychotropic substances, possessing sedative, hypnogenic and antidepressant properties.