Termite cohabitation: the relative effect of biotic and abiotic factors on mound biodiversity

1. Termites are important ecosystem engineers that improve primary productivity in trees and animal diversity outside their mounds. However, their ecological relationship with the species nesting inside their mounds is poorly understood. 2. The presence of termite cohabitant colonies inside 145 Cornitermes cumulans mounds of known size and location was recorded. Using network‐theoretical methods in conjunction with a suite of statistical analyses, the relative influence of biotic and abiotic drivers of termite within‐mound diversity on the composition and species richness of the termite community was investigated, specifically builder presence and physical aspects of the mound. 3. We found that richness inside the mound increases with mound size, and the species similarity between mounds decreases with distance. The physical attributes (abiotic drivers) of termite mounds (size and relative distance to other mounds) are the strongest predictors of termite species richness and composition. The biotic driver (presence of a builder colony) has an important, though smaller, negative effect on within‐mound termite species richness. 4. The findings suggest that the termites' physical manipulation of their environment is an important driver of within‐mound community diversity. More generally, the approach taken here, using a combination of statistical and network‐theoretical methods, can be used to determine the relative importance of abiotic and biotic drivers of diversity in a wide range of communities of interacting species.     

Abundance and activity of the bacteria-destructors of organic matter in Saline-and-Soda Lake Khilganta (South Transbaikalia) in the pH-salinity gradient

It is established that the microbial community of the bacteria-destructors in bottom sediments and crust of the soda Lake Khilganta is able to develop in a wide range of pH and mineralization. The community of bacteria-destructors functions most actively in neutral or weakly alkaline conditions and at low salt concentration. The simultaneous action of two factors—high pH and the salinity of medium—results in decrease of the number of cells and drop in the destroying activity of the community. The obtained data confirm the earlier proposed hypothesis that at high mineralization the destroying processes are inhibited, which leads to accumulation of organic matter.     

Isolation and study of polyadenylated RNA from Bacillus intermedius

A poly(A)+RNA fraction was isolated from the overall RNA of Bacillus intermedius using chromatography on poly(U) Sepharose and was shown to be electrophoretically heterogeneous. The presence of a polyadenylate segment was confirmed by hybridization with polyuridine. The biological activity of the poly(A)+RNA was proved by the translation in Xenopus laevis oocytes. The dynamics of poly(A)+RNA synthesis was studied in the course of B. intermedius growth and the content of poly(A)+RNA was assayed in the cells grown in different media.     

Strong seasonal disequilibrium measured between the oxygen isotope signals of leaf and soil CO2 exchange

The oxygen isotope composition (δ¹⁸O) of atmospheric CO₂ is among a very limited number of tools available to constrain estimates of the biospheric gross CO₂ fluxes, photosynthesis and respiration at large scales. However, the accuracy of the partitioning strongly depends on the extent of isotopic disequilibrium between the signals carried by these two gross fluxes. Chamber‐based field measurements of total CO₂ and CO¹⁸O fluxes from foliage and soil can help evaluate and refine our models of isotopic fractionation by plants and soils and validate the extent and pattern of isotopic disequilibrium within terrestrial ecosystems. Owing to sampling limitations in the past, such measurements have been very rare and covered only a few days. In this study, we coupled automated branch and soil chambers with tuneable diode laser absorption spectroscopy techniques to continuously capture the δ¹⁸O signals of foliage and soil CO₂ exchange in a Pinus pinaster Aït forest in France. Over the growing season, we observed a seasonally persistent isotopic disequilibrium between the δ¹⁸O signatures of net CO₂ fluxes from leaves and soils, except during rain events when the isotopic imbalance became temporarily weaker. Variations in the δ¹⁸O of CO₂ exchanged between leaves, soil and the atmosphere were well explained by theory describing changes in the oxygen isotope composition of ecosystem water pools in response to changes in leaf transpiration and soil evaporation.     

Structure and formation properties of the haloalkaliphilic community of Lake Khilganta

The structural features of a cyanobacterial mat from Lake Khilganta (Southeastern Transbaikal Region) developing at different values of salinity and pH were determined based on our long-term investigation of the natural community, as well as results obtained during experimentation with its laboratory analogue. At water mineralization of 40–50 g/l, Microcoleus chthonoplastes and Phormidium molle play a key role in the formation of the cyanobacterial mat. As water mineralization increases, the diversity of cyanobacteria in the natural mat increases as well, reaches its maximum at 80 g/l NaCl, and decreases at 100 g/l. In the laboratory community, Nodularia sp. prevailed. It was able to form matlike structures within a broad pH range and at a salinity of up to 50 g/l NaCl. As the water mineralization level increased up to 100 g/l or higher, a replacement of the dominant complexes occurred both in the laboratory and natural communities: cyanobacterial species were substituted with green algae.     

The manifestations of an epidemic process of typhoid infection in Moscow

The work deals with the results of typhoid morbidity in Moscow for the period of 1980-1988. The morbidity rate varied from 0.98 to 0.17 cases per 100,000 of population with a tendency towards decrease. In the structure of morbidity local cases accounted for 46.8% and cases of infection contacted outside Moscow accounted for 53.2%. The morbidity level was low throughout the whole territory, only in two districts morbidity rate was significantly higher (P = 95%) than the average morbidity rate in the whole of the city. In the group of local cases morbidity had no pronounced seasonal character, in contrast to cases due to infection contacted outside the city which were mostly registered in summer and autumn. Persons aged 21-30 years were found to be the most affected age group. The general factors, and not the contact route, are supposed to play the main role in the realization of the mechanism of infection transfer. Under modern conditions, some manifestations of the epidemic process of typhoid infection can be detected only at the level of the whole city, or even the whole country.     

Effect of TRPM8 ion channel activation on thermoregulatory response to cooling

In rats, the effect of activation of the cold- and menthol-sensitive TRPM8 ion channel on different thermoregulatory parameters: total oxygen consumption, carbon dioxide release, respiration coefficient, constriction response of skin blood vessels, muscle activity, was studied. Activation of TRPM8 with menthol even in thermoneutral conditions produces an increase in oxygen consumption and a decrease in respiratory coefficient, which may suggest enhanced non-shivering thermogenesis and lipolysis. Rapid cooling against the background of TRPM8 activation is characterized by a decrease in the temperature thresholds of all thermoregulatory responses without associated changes in sequences of their initiation as well as in enhancement of metabolic component of emergency thermogenesis which leads to improved maintenance of core temperature in conditions when external cold acts on the organism. The obtained data on the effect of TRPM8 activation on metabolic parameters in thermoneutral conditions and under cooling suggest acontinuous involvement of this receptor in regulation of total metabolism and, possibly, in determination of the type of organism's metabolism as well as in determination of organism's response to external cooling.