The Sensitivity of Resting Eggs of the Cladoceran <Emphasis Type="Italic">Moina macrocopa</Emphasis> to the Effect of Ionizing Radiation during the Reactivation of the Eggs

We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect of ionizing radiation during the reactivation of the eggs. The study showed that the resting eggs during reactivation are more vulnerable to irradiation than the resting eggs in a stage of deep dormancy. The decrease in the efficiency of egg reactivation was observed at high doses, the growth rate of juveniles, fecundity, and the number of produced clutches by females strongly decreased when resting eggs at the reactivation stage absorbed doses of 64 Gy and higher.     

The effect of benzylpenicillin on the activity of antioxidative enzymes in the erythrocytes and on methemoglobin formation in children

Activity of erythrocyte antioxidative enzymes and the content of methemoglobin were studied in 36 healthy children under preventive treatment with benzylpenicillin and in 65 healthy children of the control group. It was shown that there was relationship between the changes in the activity of superoxidodismutase and catalase and the antibiotic dose and duration of the use. After benzylpenicillin intramuscular administration for 3-4 days (the total dose of 80,000-3000000 units) the catalase activity decreased to 65.6 per cent while the activity of superoxidodismutase did not change. When the antibiotic was used for 1-2.5 weeks (the total dose of 3000000-6000,000 units) the activity of catalase and superoxidodismutase decreased to 53.6 and 82 per cent respectively. Beginning from the 3rd week of the antibiotic use the catalase activity increased to 71.6 per cent while the superoxidodismutase activity did not change and remained at the level of 84.9 per cent. The content of methemoglobin in the children treated with benzylpenicillin was about 3 times higher than that in the controls. The correlation between the activity of the antioxidative enzymes and the content of erythrocyte methemoglobin was inverse: the lower was the enzyme activity, the higher was the content of methemoglobin and vice versa. It was concluded that benzylpenicillin impaired definite balance between single electron reduction of oxygen and antioxidative protection resulting in the antibiotic adverse action i. e. increased methemoglobin formation. The effects of benzylpenicillin should be considered when it is used in combination with oxidants in treatment of children.     

The seasonal development cycle of <Emphasis Type="Italic">Aphantopus hyperantus</Emphasis> (L.) (Lepidoptera,Nymphalidae: Satyrinae) in Leningrad Province

The simultaneous influence of the photoperiodic and temperature conditions on pre-diapause and postdiapause larval development of the ringlet Aphantopus hyperantus was studied. At the short day (12 h of light a day) all larvae reached the III instar and entered diapause at all the temperatures tested (18–24°C). At the long day (22 h) the number of diapausing larvae increased with decreasing temperature, and the larvae diapaused at the III and IV instars. The I and II instar larvae (before winter) developed and grew faster under short-day, and the hibernated larvae, under long-day conditions. At the short day the growth rate of the I and II instar larvae did not depend on the temperature, and at the long day it decreased as the temperature increased. After hibernation the growth rate of the IV instar larvae increased with the temperature under long-day conditions, and did not depend on the temperature under short-day ones. Thus, acceleration or deceleration of development, depending on the photoperiodic and temperature conditions, regulated the timing of diapause in the overwintering stage (the III instar larva) and maintained the univoltine seasonal cycle. The males of A. hyperantus developed and grew faster than females while their weight at the larval and pupal stages was smaller. The thermal reaction norms for development (the lower temperature threshold and the coefficient of thermal sensitivity of development) were calculated for the eggs, IV and V instar larvae, and pupae. The coefficient of thermal sensitivity of development for the IV and V instar larvae taken together was lower, and the threshold was higher than the corresponding values for eggs and pupae. The thermal reaction norms for development of the latter stages were the same. The larvae of A. hyperantus retained their sensitivity to the photoperiod after hibernation. Resumption of development after cold reactivation occurred only under long-day conditions, whereas under short-day ones the overwintered larvae entered a repeated diapause. The possibility of photoperiodic reactivation and the absence of spontaneous resumption of development in these larvae were demonstrated.     

Modifying methylase SsoI from Shigella sonnei 47 cells

A simple and fast method for isolation and purification of SsoI methylase from the bacterial strain Shigella sonnei 47 has been proposed. The enzyme is a modifying component of host cell specificity system and protects the acceptor DNA from hydrolysis by restriction endonucleases SsoI and EcoRI. The method is based on the hydrophobic chromatography of ammonium sulphate fraction on the phenylsepharose. The enzyme preparation obtained is devoid of specific and nonspecific endonucleases traces and is stable at storage in 30% glycerol during a year. The conditions of manifestation of "stroke" activity by the enzyme were studied.     

The effect of γ-radiation on resting eggs and life cycle of cladoceran <Emphasis Type="Italic">Moina macrocopa</Emphasis>

We investigated the effects of γ-irradiation on the survival of resting eggs of the cladoceran Moina macrocopa and on the parameters of the life cycle of neonates hatched from the irradiated eggs. It was shown that γ-irradiation in a wide range of doses (from the background level to 100 Gy) had no effect on survival of eggs and mortality of neonates hatched from the irradiated eggs. However, exceeding the absorbed dose of 40 Gy sharply decreased the reproductive potential of the neonates hatched from irradiated eggs.     

Growth peculiarities of hydrocarbon-oxidizing rhodococcus and pseudomonads dissociates in mono- and mixed cultures

Growth of R-, S-, and M-dissociates of Rhodococcus rubropertinctus in mixed culture with R-, S-, and M-dissociates of Rhodococcus aeruginosa in comparison with rhodococcus monoculture cultivated on mineral nutrient medium with hexadecane has been studied. The amount of cells in the stationary growth phase has increased 10–15 times in comparison with the monoculture, and pseudomonads which dominated in population, in associations of M-dissociate of R. rubropertinctus with any dissociate of R. aeruginosa or two S-dissociates in the studied bacterial species. The emulsifying ability of the cells (maximal in R-dissociates), the synthesis of surface active compounds in pseudomonads, which is maximal in M-dissociate had the main influence on the growth of rhodococci on the nutrient medium with hydrocarbons.     

Aging exacerbates damage and delays repair of alveolar epithelia following influenza viral pneumonia

Background

Influenza virus infection causes significantly higher levels of morbidity and mortality in the elderly. Studies have shown that impaired immunity in the elderly contributes to the increased susceptibility to influenza virus infection, however, how aging affects the lung tissue damage and repair has not been completely elucidated.

Methods

Aged (16–18 months old) and young (2–3 months old) mice were infected with influenza virus intratracheally. Body weight and mortality were monitored. Different days after infection, lung sections were stained to estimate the overall lung tissue damage and for club cells, pro-SPC⁺ bronchiolar epithelial cells, alveolar type I and II cells to quantify their frequencies using automated image analysis algorithms.

Results

Following influenza infection, aged mice lose more weight and die from otherwise sub-lethal influenza infection in young mice. Although there is no difference in damage and regeneration of club cells between the young and the aged mice, damage to alveolar type I and II cells (AT1s and AT2s) is exacerbated, and regeneration of AT2s and their precursors (pro-SPC-positive bronchiolar epithelial cells) is significantly delayed in the aged mice. We further show that oseltamivir treatment reduces virus load and lung damage, and promotes pulmonary recovery from infection in the aged mice.

Conclusions

These findings show that aging increases susceptibility of the distal lung epithelium to influenza infection and delays the emergence of pro-SPC positive progenitor cells during the repair process. Our findings also shed light on possible approaches to enhance the clinical management of severe influenza pneumonia in the elderly.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0116-z) contains supplementary material, which is available to authorized users.     

Intraspecific variation of thermal reaction norms for development in insects: New approaches and prospects

The main parameters (thermal constants) characterizing the effects of constant temperatures on the duration and rate of development in ectotherms are considered. The advantages and drawbacks of the linear and nonlinear models describing the dependence of the development rate on temperature are discussed. The main patterns of interspecific variation of thermal constants in insects are described. The development of new ideas in the study of intraspecific variation of thermal reaction norms for development in insects is examined. The discrepancies in the data and their interpretation in this field are shown to result mostly from using the traditional methods of determining thermal constants. According to this method, the development rates calculated as reciprocals of the mean development times at each experimental temperature are used for regression analysis. The standard errors calculated according to this method are usually too large. Instead, a fundamentally new method is employed by the authors, according to which the individual development rates calculated for each individual are used for regression analysis of the reciprocals of the mean development times. This method reduces the standard errors of thermal constants by about an order and reveals significant differences between populations and other groups of insects. New data on intraspecific variation of the thermal reaction norms for development in Myrmica ants, the linden bug Pyrrhocoris apterus, and Calliphora blowflies are briefly described and discussed. The possible adaptive significance of these forms of intraspecific variation is discussed. The prospects of research in this new field are outlined.