[en] The most important stages of knowledge development in Antarctic marine microbiology, from the beginning of this century, were reviewed and systematized. Multi-annual studies from 1978 to 1988 demonstrated a great variation in total and saprophytic bacterial numbers at different sites in the Antarctic. These sites included inshore waters (Admiralty Bay), open ocean waters (Drake Passage and Bransfield Strait), and the vicinity of pack-ice in Scotia Sea. Bacterial biomass, which is highly comparable to that of other organisms, combined with many times shorter bacterial generation time, (in case of saprophytic population it amounts to 17.5 h), must have profound consequences for cold marine ecosystems of the Antarctic. Higher numbers of bacteria were found in open surface waters, down to 75 m. High transparency of oceanic offshore waters causes that UV radiation (280-400 nm) penetrates to biologically effective depths to about 50 m. The UV-B sensitivity of 25 Antarctic bacterial strains from the following various habitats: coastal waters, krill stomach, krill feaces, water ice edge, water below ice and sea ice was examined. The strains were irradiated in UV-B transparent cuvettes on an optical bench with artificial UV-B (290 nm; 1.21 W. m^-2 ] during 10 hours in temperature 4^oC. ATP (adenosine triphosphate), number of bacterial cells, lethal effect of UV-B and survival of bacteria, total bacterial number, biovolume and changes in biochemical/physiological properties have been estimated. The results indicated a high interspecific variability in the sensitivity against UV-B. The ATP content show at the beginning of irradiation an increase (reaching typical for individual species maximum, at 0.5 to 4 hours) and afterwards a decrease to the level above zero (also characteristic of species). We hypothesize that first anabolic processes and after that catabolic processes are destroyed by UV. Survival of the bacterial strains ranged between 0 and 3.2%. Among 25 bacterial strains only six were not able to survive 10 hours UV-B irradiation. The most sensitive strains were isolated from habitats protected from UV radiation (krill stomach, sea ice). The additional experiment, showing the lethal effect of UV-B for bacteria, throws light on the importance of shadowed environmental niches for bacterial survival in regions of the highest UV irradiance. Total cell number did not change significantly when exposed to UV-B radiation for 10h while without UV bacterial number increased by 27% during this period. The biovolume of strains used in this study which ranged from 0.14 to 13.7 (micro)m³ cell^-1 also did not change significantly after 10 hours irradiation. Preliminary results show that the API 20NE test can be used to show changes in enzymatic abilities. Even 10 hours irradiation were not able to inhibit all enzymatic processes demonstrated by API 20NE system. The high variability in UV-B sensitivity of Antarctic bacteria may led to shifts from normal bacterial strains to more resistant. and thus to establish bacterial community adapted to life at risen UV-B level in the upper layer of Antarctic marine ecosystems. (author)

[en] The manners of insect sterilization are presented. The theoretical bases are given. Susceptibility of different kinds of insects to sterilizing and lethal irradiation is mentioned. Causing of sterility in Lepidoptera is shortly described. The results of sterile Callitroga hominivorax release are presented. (A.S.)

[en] Recent advances in positron emission tomography (PET) and other brain-imaging techniques have made it possible to visualize the working brain while the human subject is thinking, speaking or planning an action. PET provides researches with an opportunity to infer the neuroanatomy of a given function. Subjects either inhale or are injected with a radioactive material that binds to a physiologically active compound in the body. This serves as a tracer of blood flow and metabolic processes that reflect the activation of a given structure by emitting gamma rays which may be detected through a tomograph. PET research has produced findings that extend our knowledge on several important issues such as cerebral representation of language, perception, attention or memory. It has also proven to be an important source of information for clinical diagnosis of various neurological and psychiatric diseases. The present article provides a short review of main achievements in those fields. However, functional brain imaging is not exempt from methodological and theoretical difficulties. The main limitations of the method have been outlined. (author)

[en] The analysis of chromosomal aberrations is one of the most important methods of investigating the effects of ionizing radiation on living cells. For a long time only structural unstable-type aberrations, like dicentrics, could be identified in uniformly stained chromosomes. The introduction of chromosome banding in the seventies allowed for the first time to analyze stable-type aberrations, such as translocations, however, the technical difficulties associated with this technique prevented its wide application in radiation biology. At the end of the eighties, the technique of chromosome painting was invented. With its help it is possible to hybridize 'in situ' fluorochrome-labelled DNA of individual chromosomes, so that any inter chromosomal rearrangements are easily detectable as color discontinuities. The analysis of radiation-induced translocations in painted chromosomes is presently being introduced in biodosimetry of human peripheral lymphocytes. The advantage of this system lies in the fact that, unlike unstable-type aberrations, the frequency of translocations in a proliferating cell population remains constant with time. This could allow a precise, retrospective estimation of the dose applied a long after exposure to radiation. Chromosome painting has also been used to investigate the mechanisms underlying the formation of radiation-induced chromosomal aberrations, and may play a role in estimation of radiosensitivity of tumors prior to radiotherapy. (author). 23 refs, 3 figs

[en] There is an increasing body of evidence that mutagenic agents (biological, chemical and physical) play an important role in the etiology of human diseases. Mutations may occur in the germinal as well as in the somatic cells. Mutations of the germ cells may result on infertility or fertilization of damaged cells, the later leading to abortion or birth of a malformed fetus. Somatic-cells mutations may have various biological effects, depending on the period of the human life at which the mutation occurs. If it occurs during the prenatal life, a teratogenic or carcinogenic effect will be observed. If the somatic cell is damaged during the postnatal life, this will lead to neoplastic transformation. Therefore it is extremely important to know the mutagenic, teratogenic and carcinogenic effects of various biological, chemical and physical agents in order to eliminate them from our environment. (author). 13 refs, 4 figs, 1 tab

[en] DNA repair plays a crucial role in protection of human genetic material against genotoxic agents including carcinogens, ensuring genome stability. Variability of DNA repair was observed on many levels. These are several mechanisms of damage removal and a number of enzymes taking part in the specific steps of DNA repair. Hence, variations in efficiency of DNA repair among healthy individuals can be explained in term of genetic polymorphism. There are also some exogenous and endogenous factors affecting the DNA repair machinery in human organism. The first group includes diet and genotoxic exposure whereas the second comprises age (negative linear correlation) and health status. Within the group of health status factor neo-plasticity and diseases with hereditary DNA repair deficit are discussed extensively. The well documented heterogeneity of DNA repair inside the genome concerns differences between classes of DNA (e.g. nuclear v. mitochondrial or repetitive v. single copy) and preferential repair of activity transcribed genes. The main message of the article is that DNA repair should be recognized as fairly individual and, moreover, as being modulated by many factors. (author). 25 refs, 2 figs

[en] Characteristics of polymorphic sequences of DNA, especially satellite, mini satellite and micro satellite sequences are presented. Own experience from the use of multi and single locus analysis of DNA in paternity testing has been compared with the results of research in other laboratories. Critical points of both types of analysis are discussed. (author). 53 refs, 4 figs, 2 tabs

[en] The types of defects and polymorphisms leading to hereditary susceptibility to cancer include proneness to increased DNA damage, recessive syndromes of faulty DNA repair and differentiation, as well as dominant mutations of cell cycle and control proliferation. The cancer susceptibility syndromes inherited in a dominant fashion are caused by mutations in tumor suppressor genes. These genes are recessive in relation to wild type alleles. In two syndromes of hereditary mutations in tumor suppressor genes (Rb and WT2), their expression 'in vivo' may be influenced by the sex of the transmitting parent, what points to modulation by imprinting. Genetic heterogeneity of the population in susceptibility to genotoxic agents is related to the individual variation in acceptable levels of exposure to agents and factors, such as products of incomplete combustion (PIC), UV ('xeroderma pigmentosum') and ionizing radiation ('ataxia telangiectasia'). DNA damage and adducts are considered to be indicative of genotoxic exposure and its effect as well as modulation of carcinogenic damage by genetic polymorphisms. Gene and protein polymorphisms are considered as markers of increased individual risk. Since environmental factors are considered to be able to control, the individual susceptibility to enhanced DNA damage and environmentally induced cancers could be counteracted by decreasing the levels of contamination or exposure. This explains the wide interest in markers of this individual sensitivity. Most of the postulated markers of sensitivity to PIV do not, however, prove to be generally applicable in that sense. Their prognostic value is limited either by low amplitude of the effect, or by their character specific either to the population or to the cancer type. The polymorphisms most relevant to cancers induced by PIC exposures may be those of inductibility of benzopyrene hydroxylase, and some other DNA polymorphisms concerning the CYP1A1 gene. (author). 24 refs, 1 fig., 3 tabs