[THE CONTENT OF MERCURY IN SEDIMENTS AND THE CLAMS UNIO PICTORUM FROM THE URAL RIVER].

There was investigated the mercury total content in bottom sediments and some bodies of clams from the area of the middle reach of the Ural river near the Orenburg city. In bottom sediments there was revealed an excess of the ecological standard for mercury. There was noted the uneven distribution of toxicant in bodies of clams: the maximal contents was detected in hepatopancreas, minimal--in "foot", that apparently is determined by the unequal metabolitic activity of these tissues. The highest concentration of mercury in the tissues of clams was noted at the station "Ural river above the camp" Dubki".

[Mercury in the streams and reservoirs in the territory of the Orenburg Region].

The State Education Institution of Higher professional education "The Orenburg State Medical Academy of Federal Agency in Public Health and Social Development". The state of some freshwater streams and reservoirs in the Orenburg Region was estimated from the level of mercury in the water extract of their bed silt. The concentration of this pollutant is shown to exceed the set standards.

[Rare-earth metals as a factor in mutagenicity].

Both the regions of the Orenburg Region area and individual examined streams and reservoirs were shown to be characterized by a varying load index for rare earth elements. The total level of rare earth elements was directly correlated with different types of mutations.

[Monitoring of the levels of metals in the bottom sediments of rivers in the central area of the Orenburg Region].

Among the pollutants of the biosphere, heavy metals present the greatest hazard since they show a high stability and toxicity and are able to migrate in the water ecosystems and to accumulate in the bottom sediments and hydrocoles, by impairing the stability of hydrobiocenoses. Chemical monitoring of the level of bottom sediments of rivers was made in the Central district of the Orenburg Region. Samples were taken at 11 stations of the Central district of the region and 5 stations in a district of Orenburg. The analysis of the findings indicated that the content of copper, zinc, cadmium, lead, chromium in the bottom sediment samples was not greater than the maximum permissible concentration (MPC) at any station and that of nickel did not exceed MPC by 1.3-2.6 times.

[Typification of opisthorchiasis foci in the Orenburg Region].

On making expedition and studying the functioning of opisthorchiasis foci in the Orenburg Region, the authors have districted the region and identified 3 types of districts according to the pattern of Opisthorchis transmission: 1) areas lacking the conditions for forming an invasion foci; 2) those having all links of the focus, but lacking pathogen circulation; and 3) those having all conditions for pathogen circulation and the human beings are infected from the local infested fish--Type C. By studying opisthorchiasis in the Orenburg Region, the authors have established the rate of morbidity growth and their nonuniform distribution in this region. The findings have formed the basis of dividing the Orenburg Region by the endemicity of opisthorchiasis into 4 types of areas: non-endemic, low, moderate, and high endemic. The results of districting the region by the endemicity of areas, the nature of foci, and the social and natural factors determining an epidemiological process have formed the basis of a differential package of preventive measures against opisthorchiasis in the Orenburg Region.

[Rivers of the Orenburg Region: maintenance of the life cycle of Opisthorchis felineus].

Specific hydrological and climatic features contribute to the functioning of the parasitic system egg--mollusk--fish--man parasitic in the Orenburg Region. Four types of areas, such as floodplain, suprafloodplain-terrace, valley-ravine, and near-lake ones, are adequate for the formation of a natural opisthorchiasis focus. The periods of active functioning of a natural opisthorchiasis focus have been established in the Orenburg Region. These include the emergence of the first cercariae and, therefore, the first (in this epidemic season) infection of the supplementary host (fish) occur in mid-June to early July and then 6 weeks later metacercariae achieve invasiveness in the fish muscles and subcutaneous fat, as a result the first infection of the final host with Opisthorchis occurs in early August.

[Effects of some species of hydrocoles on the development of ascarid eggs].

The study established that aquatic plants differently affected the development of ascarid eggs. Some species of algae exerted a damaging effect on ascarid eggs only at early stages of embryogenesis while others did at its late stages, but some species did not produce any noticeable effect on the development of the eggs. A great difference was found in the development of ascarid eggs in different seasons. Gas exchange conditions were ascertained to affect the development of ascarid eggs. Analysis of the effect of egg lysozyme versus mollusk one on ascarid embryogenesis demonstrated that the latter had a more pronounced antiparasitic activity.

[Lysozyme of the mollusk Unio pictorum and the sensitivity of alkanotrophic rhodococci to its effect]. / Lizotsim molliuska Unio pictorum i chuvstvitel'nost' k nemu alkanotrofnykh rodokokkov.

A preparation of lysozyme from a freshwater bivalve, Unio pictorum, has been isolated by sorption to chitin, and its physicochemical properties have been studied. An assessment of the sensitivity of 48 strains of rhodococci, belonging to the species Rhodococcus rubber, R. luteus, and R. erythropolis (Specialized Collection of Alkanotrophic Microorganisms of the Institute of Ecology and Genetics of Microorganisms, Ural Division of the Russian Academy of Sciences), which were isolated from diverse natural waters, to lysozyme of the mollusk Unio pictorum demonstrated that the three species differ in their sensitivity to its effects. The high resistance of rhodococci to lysozyme is indicative of their considerable permanence in hydrobiocenoses (and, therefore, ability to maintain self-purification of microbiocenoses from hydrocarbons).

[Lysozyme of hydrobionts and its role in self-purification of water reservoirs]. / Lizotsim gidrobiontov i ego rol' v protsessakh samoochishcheniia vodoemov.

Model experiments were carried out to study the effects of hydrobiont lysozyme on self-purifying processes of water reservoirs through its participation in the formation of a community of destructive microorganisms. Lysozyme-resistant forms have been found to lie at basis of bacterial cenosis of the Urals, among which there are lysozyme-active and anti-lysozyme-active ones, their population shows an inverse relationship. The exogenous lysozyme that enters the water reservoir in the period when there is a change in the dominant forms of hydrobionts affects the composition of bacterial cenosis by preserving anti-lysozyme-activity with a high activity (6-8 (g/ml), which causes a change in the microbial community of water reservoir, thus affecting the processes of its self-purification. The bacteria having ALA, which do maintain the capacity of a water reservoir for self-clearance from organic substance, persist under the action of endogenous lysozyme of phyto- and zooplankton among saprophytic microorganisms that are destructive agents in the biocenosis.

[Effect of thermal power stations on the sanitary and biological conditions of water reservoirs]. / Vliianie teplovykh élektrostantsii na sanitarno-biologicheskii rezhim vodoemov.

Discharge of thermal waters from power stations can result in the development of thermophilic microorganisms in the water reservoirs and increased water pollution. Increased water temperature changes relationships between lysozyme-active and antilysozyme-active bacteria. The quality of water gets worse.

[The lysozyme-antilysozyme functional system in hydrobionts and its role in forming aqueous biocenoses]. / Funktsional'naia sistema "lizotsim-antilizotsim" u gidrobiontov i ee rol' v formirovanii vodnykh biotsenozov.

Lysozyme activity has been evaluated in hydrobionts of different trophic levels: algae, zooplankton and germs. The existence of the functional system "Lysozyme of hydrobionts--antilysozyme of germs", functioning as a regulating element in the formation of aqueous microbiocenosis, has been substantiated on the basis of data provided by laboratory experiments and investigations carried out in natural water pools.