Interaction of alkaline earth and transition metals with Na+/Ca2+-plasma membrane exchanger in secretory cells of the gastric gland

Investigation of Na(+)-dependent Ca2+ uptake into the secretory cells of isolated gastric glands from guinea pig with the use of calcium isotope (45Ca2+) has been performed. The presence of Na+/Ca(2+)-exchanger in the cells membrane was established. Ca2+ uptake into the cells through Na+/Ca(2+)-exchanger was competitively inhibited by the number of alkaline earthy and transient metals" cations. Potency of inhibition increases in such an order (Ki, mM): Ba2+ (117.7) < Sr2+ (53.4) < < Mn2+ (15.2) < < Co2+ (12.8) < Cd2+ (8.6). By one-factor dispersion analysis it was shown that potency of inhibition depends on ionic radii and hydration enthalpy of metals" cations (hx2 = 93.93-94.15%) and also on stability constants of their complexes with oxygen-containing bioligands (acetic, aspartic and glutamic acid) (hx2 = 82.32-82.47%). Dependence of inhibitory constants from ionic radii is most adequately described by the parabolic equation, such dependence from hydration enthalpy and stability constants with oxygen-containing bioligands--by exponential or multiplicative equations. The conclusion has been made that velocity of Ca2+ transport through Na+/Ca(2+)-exchanger and potency of its inhibition by metals" cations is determined by the interaction between energy of their interaction with cation-binding sites of transport system and energy of hydration. Energetics of such interactions mainly depends on the steric conformity between the metal cation and cation-binding sites of the exchanger.     

Enzymes of direct, excision, and corrected systems of repair of higher and lower organisms and their biological roles

DNA repair is of paramount importance to protect the integrity of the cell genome. Over the last decade, DNA repair enzymes have been intensely studied owing to their role in mutagenesis, carcinogenesis, and aging. This led to discoveries of novel enzymes, protein factors as well as their intermolecular complexes involved in the repair process. Alternative pathways of cell response to the same type of damage were identified. Data on the tertiary structure of a number of enzymes and mechanisms of their molecular interaction were obtained. This paper is an overview of latest advances in the research of cell response to DNA damage via direct, base and nucleotide excision, and mismatch DNA repair.     

Habitat selection and metapopulation structure: a multi-year study of distribution of the Hodgson's pipit, Anthus Hodgsoni Richm. (Aves, Passeriformes)

Numbers and distribution of the Hodgson's pipit (Anthus hodgson Richm.: Aves, Passeriformes) were studied in the Yenissei middle taiga region over an area of about 450 sq km. Distribution of breeding pairs was mapped on fixed study plots (up to 450 ha in total) annually during 15 years. Habitat properties were described and measured in detail on 53 4-ha homogeneous plots within the area. It is shown by means of multiple regression, an average bird abundance over these plots depends on five habitat features (R2 = 0.74) including development and accessibility of moss cover and absence of a potential competitor, the tree pipit (A. trivialis L.). Correlation with these factors ruterated every year, therefore the average bird abundance was used as an index of habitat favourability. Density deviations from the mean in years of high and low numbers appeared to be closely related to habitat favourability; in particular, the relationship can alter the sign depending on the spatial scale of population structures. Changes in abundance reversely related to favourability in adjacent habitats, according to the prediction of despotic distribution hypothesis (Fretwell, Lucas, 1970), strictly indicating dominance behaviour during selection of a breeding territory. The numbers in larger population groups occupying a patchy habitat complex changed synchronously and proportionally to their average habitat quality. This assumes another mechanism governing the distribution of individuals, requiring no local knowledge and no dominance relationships. Dynamics and distribution of individuals among population groups of different hierarchic ranks agree with investigations on establishing of individual site fixation in birds and allow splitting the process into four consecutive steps. 1. During the juvenile dispersal, birds spread around quite evenly, disregarding of habitat quality. This maintains entirety of the metapopulation and occupation of isolated habitat spots. 2. The juvenile dispersal ends with switching to a search for a nearest site containing potential breeding territories. Such a site gets imprinted as the site for next breeding. According to our data, it covers an area of a few square kilometers. 3. During the pre-breeding period, an individual chooses a territory regarding to the favourability, but dominance of old residents forces it to search around for an empty patch within the imprinted area. As a result, dominance relationships affect both breeding density in best habitats and availability of empty patches. 4. The next years, an individual keeps connection with the breeding site fixed due to site tenacity. Rising of the social status allows the individual to occupy a better territory in future. Thus, a population group proportionate to individually imprinted area, with a concentration of favourable patches in the central part, comprises an elementary structural and functional unit of a metapopulation. Its individual members share the same well-known imprinted area and the social structure in common. Its numbers are regulated by density-dependent dominance relationships. Individuals spread over such groups in proportion to their carrying capacity in density-independent manner. Groups with best habitats can be more profitable at population lows, and less densely populated ones can offer more profit at population tops. Despite this, lack of information restricts profitable movements between them. Hence each group offers the same average fitness to its members.     

Genetic aspects of species structure of the compost worm Eisenia foetida (Sav.) (Oligochaeta, Lumbricidae)

Distribution of frequencies alleles of polymorphous loci of peroxidase (Pox), leucineaminopeptidase (Lap), phosphoglucomutase (Pgm) and octanoldehydrogenase (Odh) were studied by electrophoresis in polyacrylamide gel in 22 local samples of Esenia foetida in Russia (European part), Ukraine, Kazakhstan and Kirghizia. The samples form two spatial groups--"northern" and "southern", distinguished by set of alleles in every studied locus. The "northern" groups is formed by local populations of European Russia from Murmansk region on the north to Smolensk region on the south, and also by cultivated population of selection line "red California hybrid". The "southern" group is formed by local populations on the territory of Russia from middle Volga to the North Caucasus, Ukraine, Kazakhstan, Kirghizia, cultivated populations from Kirghizia and Portugal. High degree of genetic difference between samples and independence of alleles frequencies distribution from geographical location and habitat allows to consider almost all studied groups as separate populations. Statistical processing of Nei genetic distances (Nei, 1972) revealed reliable differences between averages of within- and intergroup distances. Besides, discrete differences between intervals of significance of genetic distances were revealed. The results indicate that on the studied territory E. foetida has hierarchical two level structure. The first level is formed by local populations differed by frequency of the same alleles. The second level is formed by local populations, united into spatial groups, that are qualitatively distinguished by the set of alleles in the same loci.     

Serous meningitis

During the second half of the 1950s serous meningitis and other enterovirus-induced diseases played one of the leading roles in human pathology in the world. Since the introduction of oral poliomyelitis vaccine (OPV) into wide medical practice from the beginning of the 1960s and during the subsequent decades the number of epidemics and the morbidity level in enterovirus-induced diseases sharply dropped. This was probably due to the interference of enteroviruses circulating in nature and vaccine polioviruses in the intestine of vaccinated children. At the beginning of the XXI century a tendency towards a growth in the morbidity of serous meningitis of enterovirus etiology was noted. This growth was probably due to a sharp decrease in the level of revaccinations of children with OPV. At the age of 2 to 14 years, most affected by enteroviruses, children were not vaccinated with OPV and they were thus left unprotected. The materials on the epidemiology of serous meningitis and recommendations on etiological diagnosis, as well as on the patients hospitalization and the vaccination of children with OPV as a nonspecific antiepidemic measures based on the phenomenon of virus interference are presented.     

Legionella natural biofilms and their role in epidemiology of the infection: methods of study and modelling

Ability of Legionella species to form biofilms in association with other microorganisms is the key factor of their spreading in potentially dangerous water systems. Ability of different strains of Legionella to form monospecies biofilms as well as biofilms in association with Pseudomonas aeruginosa in constant conditions was analyzed. It was shown that ability of Legionella strains to form monospecies biofilms correlates with their ability to persist in biofilms formed by P. aeruginosa.     

The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).