Catálogo de publicaciones - libros

This paper provides a short account of the life and work of Nikolay Vladimirovitch Timoféeff-Ressovsky (1900-1981), with special reference to the 1935 monograph on the nature of the gene mutation structure by Timoféeff-Ressovsky, Zimmer, and Delbrück, its origin, its role in the development of molecular biology, and the part played in Timoféeff’s own life.

The main contributions to the biology made by N.V. Timofeev-Ressovsky and his co-authors (in “three gentlemen paper”, 1935) were: radiobiological approach to the mutation process, materialization of the gene as a macromolecule and foundation of molecular biology. These directions appeared as development of the template principle, offered previously by N.K. Koltzov, the teacher of Timofeev. Finally Timofeev formulated his principle of con-variant reduplication, which united two main biological features - inheritance and variations as a single one. Study of primary lesions and repair was added to the theory of mutations from this point of view. Nevertheless, we have no satisfactory definition of mutation so far and even contemporary classification of types of variations is contradictory now. The situation is explainable by the fact that the classification was introduced rather from the phenomenological approach than from the mechanisms underlying the variation phenomena. It is proposed to divide variations for two groups: those connected with replication of genetic material and those connected with expression of genetic information. This classification should be introduced without apriory division of variations on inherent and non-inherent because the same mechanisms may be involved both in inherent and non-inherent variations, depending upon taxonomic position and stage of ontogenetic development of the organism.

Theoretical fundamental and methodological approach to the investigations of the radionuclide behaviour in biogeocenosis was made by the outstanding researcher N.V. Timofeeff-Ressovsky. He performed and supervised the first investigations of the radionuclide behaviour into the simple links as soil-solution, soil-plant, water-hydrobionts. Later his students and adherents started a new trend in radioecology, studying the radionuclide migration and biological effects on natural ecosystems of land and internal reservoirs. N.V. Timofeeff-Ressovsky’s views and ideas are corresponded with theory of the sick plates of the Planet which is being elaborated as a part and parcel of the contemporary ecological doctrine of Russia.

Without question biospherology is primarily a Russian discipline, as its appearance is closely related to Russian scientists such as V.V. Dokuchaev, V.I. Vernandsky, and N.V. Timoffeev-Ressovsky. The role of V.I. Vernadsky, the student of the founder of genetic pedology, V.V. Dokuchayev, in its creation is especially great, for he discovered the phenomenon of living matter which forms the biosphere. With his theory of living matter he was also the first in the history of science to place life in its proper position in the general picture of the universe and discovered fundamental laws which control geochemical acitivities of living matter in the biosphere. In the first half of the previous century V.I. Vernadsky founded a vitally important science for the future of mankind that we have named biospherology.

The impact on Western Europe of the Chernobyl accidents is assessed. In particular an evaluation of the contamination of air, soil, seawater and food with special reference to geographical and orographical situations.

The rate of chromosome aberrations in cells of freshwater snail ( Lymnaea stagnalis L.) embryos and in the apical meristem of roots of common reed ( Phragmites australis (Cav.) Trin. ex. Steud.) and arrowhead ( Sagittaria saggitifolia L.) from reservoirs within the Chernobyl exclusion zone have been analyzed. The absorbed dose rate for hydrobionts living within the littoral zone of water bodies, due to external irradiation and radionuclides incorporated in tissue was in the range from 0.0018 to 3.4 Gy /year. The highest value was measured for hydrobionts from lakes within the dammed territory on the left-bank flood plain of the Pripyat River. The lowest doses were measured for specimens from the water courses. The hydrobionts from the heavily contaminated lakes are characterized by the maximal rate of chromosome aberration – about 20– 25%. The chromosome aberration rate of hydrobionts from conditionally clear was on average 1.5%, and the maximal rate does not exceed 2.5%.

The results of long-term field experiments in the 30-km Chernobyl NPP zone, in the vicinity of the radioactive wastes storage facility (Leningrad Region), and in Bryansk Region affected by the ChNPP accident that have been carried out in our laboratory on different species of wild and agricultural plants are discussed. These findings indicate that plant populations growing in areas with relatively low levels of pollution are characterized by the increased level of both cytogenetic disturbances and genetic diversity. The seeds from plant populations experiencing a mancaused impact showed a higher radioresistance than the reference ones. Therefore, the chronic low-dose exposure appears to be an ecological factor creating preconditions for possible changes in the genetic structure of a population. These processes have a genetic basis; therefore, understanding changes at the genetic level should help in identifying more complex changes at higher levels. Presented findings add to filling a major gap in our knowledge on remote effects of man-made impact on plant populations and ecosystems.

Earlier was shown that in populations around the Nuclear Power Plant, the seed survival can decrease by up to 20%, statistical simulations showed that CAs can appear independently and Poisson-distributed (P) as well as correlative enhanced and geometrical-distributed (G) (Korogodina et al ., 2004). Our aim was to determine the regulatory mechanisms of viability and variability of seed plant populations. We showed that damage transmission in meristem (bystander effect) is described by relay-race scheme and corresponds to G-distribution. We showed that P-subpopulation did not change significantly, whereas value of G-fraction did with dose/dose rates. We conclude that G-machinery plays an adaptive role.

The mutation occurrences at 9 cytogenetic characters in bone marrow cells in different vole’s species which were trapped in Chernobyl’s zone with various levels of radionuclide pollution were analyzed. The spontaneous spectra of cytogenetic anomalies in bone marrow cells are characterized by the species-specific traits in the voles both on predominance of cytogenetic anomalies and also on evolving into anomalies of the individual chromosomes. In conditions of chronic ionizing irradiation speeding cell proliferation in different vole species and also increasing the frequency of those cytogenetic anomalies, which had species-specific particularities is investigated in vole species.

Resident population in territories contaminated by long-lived radionuclides receive most of the radiation dose by internal irradiation. Under these circumstances, the main radiation protection measure is minimization of radionuclide transfer into organisms through food and water. First, this can be achieved by food processing, using special technologies reducing the content of radionuclides in food; second, substances accelerating excretion of radionuclides from the organism and stimulation of recovery processes can be exploited.