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AbstractThe brief exposure of recently ovulated mouse oocytes to a dilute solution of ethanol in vitro for 1, 3, or 5 min induced a uniform high incidence of parthenogenetic activation. The majority of parthenogenones developed a single haploid pronucleus after the extrusion of a second polar body. The proportionate incidence of this parthenogenetic class was significantly reduced as the duration of ethanol exposure increased from 1 min to 5 min. There was a concomitant increase in the incidence of parthenogenones that developed two haploid pronuclei following failure of extrusion of the second polar body. Cytogenetic analysis of the ethanol‐induced single‐pronuclear haploid parthenogenones at metaphase of the first cleavage division clearly demonstrated that a significant proportion were aneuploid. The incidence of aneuploidy observed was directly related to the duration of ethanol exposure. G‐band analysis of the aneuploid metaphases revealed that the chromosomes were not randomly involved in the malsegregation events. This observation may be a reflection of the relationship of particular chromosomes to the meiotic spindle apparatus rather than on any specific property of the agent to which they were exposed. It is believed that ethanol disrupts the organisation of cytoskeletal elements and, in particular, interferes with the processes of chromosome segregation at the second meiotic division.

Melanin obtained from Aureobasidium pullulans and Cladosporium resinae was an efficient biosorbent for copper. Copper uptake could be expressed using various adsorption isotherms; melanin from A. pullulans obeyed Freundlich and Langmuir isotherms whereas C. resinae melanin followed the BET isotherm indicating a more complex type of adsorption than in A. pullulans. In general, uptake capacities of melanin were greater than for intact biomass and the higher uptake by pigmented rather than albino biomass could be correlated with the presence of melanin. Cu2+ was less readily desorbed from melanin by dilute mineral acids than from intact biomass and again, the relative ease of Cu2+ desorption from pre-loaded pigmented or albino biomass was correlated with the presence or absence of melanin. Mg2+ and Zn2+ appeared to be the most effective cations for desorption with Na+ and K+ the least effective. The addition of melanin to a coppercontaining culture of the albino strain of A. pullulans resulted in some reduction of toxicity.

Summary.A simple technique for assessing the Gram positivity of dried smears of bacteria is described. Standardized smears on glass slides are decolourized for a specified time and the colorimetric level of crystal violet loss into the decolourizer taken as a measure of Gram positivity. The technique gives comparative values between strains and has been successfully used in several different experimental conditions.

Abstract Simulated climate-warming experiments have provided important insights into the response of terrestrial ecosystems, but few have examined the impacts on agricultural insects, particularly those associated with the ecosystem service of biological pest control. Within a spring-sown wheat crop, we artificially increased temperature by 2 °C and precipitation by 10% in a short-term (April to August 2013) replicated open-field experiment and examined the impacts on coleopteran (mainly Carabidae) diversity and ‘activity-densities’. Diversity indices decreased as a result of warming but were not affected by extra precipitation. We found a significant increase in activity-densities of the four most trapped species due to warming, which was responsible for observed changes in diversity. However, Staphylinidae beetles were negatively affected by the warming treatments while other, less common species were not affected. We provide the first experimental evidence of climate-driven impacts on an important farmland insect community. We discuss the implications of our results in the context of biological control and top-down effects across trophic levels.

This study investigated the effects of long-term chloroquine and ethanol administration on renal fluid and electrolyte handling and kidney structure. Male Sprague-Dawley rats were orally administered with chloroquine diphosphate (20 microg kg(-1) bw) and/or ethanol (1.6 g kg(-1) bw) every third consecutive day for 4 weeks. Urine volume and total urinary outputs of Na+ and K+ were determined from 24-h samples. For detailed renal studies, rats were subsequently anaesthetised and challenged with a continuous jugular infusion of 0.077 M NaCl at 150 microl min(-1) 24 h after the last treatment. After a 3-h equilibration period, urine flow, Na+ and K+ excretion rates were determined over a 4-h period. Plasma concentrations of AVP and aldosterone were measured in unanaesthetised rats and in anaesthetised rats after hypotonic saline infusion. In separate groups, the rats were anaesthetised with an overdose of ether after 4 weeks of treatment and part of the right kidney was quickly collected and routinely processed for light microscopy. Chloroquine decreased Na+ excretion and increased plasma aldosterone concentrations in anaesthetised rats. Ethanol alone did not alter urinary Na+ outputs or aldosterone levels. Combined chloroquine and ethanol increased renal Na+ excretion, but did not affect plasma aldosterone levels. In unanaesthetised animals all treatments increased aldosterone levels by comparison with control rats. Urinary Na+ excretion was decreased by separate administration of either chloroquine or ethanol, but increased by combined treatment. Microscopic studies showed that concurrent chloroquine and ethanol administration induced extensive damage of the proximal tubule and collecting ducts cells. The results of this study suggest that alcohol consumption and chloroquine administration could result in diminished renal function possibly due to alteration of renally active hormones or kidney morphology.

Abstract We investigated changes in the physical and chemical properties of rapeseed straw after treatment with different doses of 60 Co γ-irradiation (0 kGy-1200 kGy). Raman spectra, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) analyses of the pretreated samples showed that the irradiation partially destroyed the intra- or intermolecular structure of rapeseed straw. Particle size distribution and specific surface area analyses suggested that irradiation decreased the particle size, narrowed the distribution range, and increased the specific surface area. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) curves showed that increasing the irradiated dose decreased the thermal stability of the treated rapeseed straw and increased the reactivity. Elemental analyses suggested that the oxygen content slightly increased, suggesting that oxygen in the air may be involved in the reaction. These results demonstrate that γ-irradiation can induce a series of changes in the physical and chemical properties of rapeseed straw.

The oxygenation of haemoglobin is accompanied by structural changes in the subunits triggered by shifts of the iron atoms relative to the porphyrin and, in the β-subunits, also by the steric effect of oxygen itself. The oxygen-free form is constrained by salt-bridges which are broken by the energy of haem–haem interaction with the release of H+. 2,3-Diphosphoglycerate may add to the constraints by being stereochemically complementary to a site between the β-chains ; this complementarity is lost on oxygenation.

AbstractClimate change globally affects soil microbial community assembly across ecosystems. However, little is known about the impact of warming on the structure of soil microbial communities or underlying mechanisms that shape microbial community composition in subtropical forest ecosystems. To address this gap, we utilized natural variation in temperature via an altitudinal gradient to simulate ecosystem warming. After 6 years, microbial co‐occurrence network complexity increased with warming, and changes in their taxonomic composition were asynchronous, likely due to contrasting community assembly processes. We found that while stochastic processes were drivers of bacterial community composition, warming led to a shift from stochastic to deterministic drivers in dry season. Structural equation modelling highlighted that soil temperature and water content positively influenced soil microbial communities during dry season and negatively during wet season. These results facilitate our understanding of the response of soil microbial communities to climate warming and may improve predictions of ecosystem function of soil microbes in subtropical forests.