Application of Fungal and Bacterial Production Methodologies to Decomposing Leaves in Streams

As leaves enter woodland streams, they are colonized by both fungi and bacteria. To determine the contribution of each of these microbial groups to the decomposition process, comparisons of fungal and bacterial production are needed. Recently, a new method for estimating fungal production based on rates of [(sup14)C]acetate incorporation into ergosterol was described. Bacterial production in environmental samples has been determined from rates of [(sup3)H]leucine incorporation into protein. In this study, we evaluated conditions necessary to use these methods for estimating fungal and bacterial production associated with leaves decomposing in a stream. During incubation of leaf disks with radiolabeled substrates, aeration increased rates of fungal incorporation but decreased bacterial production. Incorporation of both radiolabeled substrates by microorganisms associated with leaf litter was linear over the time periods examined (2 h for bacteria and 4 h for fungi). Incorporation of radiolabeled substrates present at different concentrations indicated that 400 nM leucine and 5 mM acetate maximized uptake for bacteria and fungi, respectively. Growth rates and rates of acetate incorporation into ergosterol followed similar patterns when fungi were grown on leaf disks in the laboratory. Three species of stream fungi exhibited similar ratios of rates of biomass increase to rates of acetate incorporation into ergosterol, with a mean of 19.3 (mu)g of biomass per nmol of acetate incorporated. Both bacterial and fungal production increased exponentially with increasing temperature. In the stream that we examined, fungal carbon production was 11 to 26 times greater than bacterial carbon production on leaves colonized for 21 days.     

Stomatal sensitivity to abscisic acid following water deficit stress

Short-and medium-term stresses (1 and 24 h, respectively) wereapplied to detached leaves of Commelina communis L., resultingin both cases in a final leaf cell water potential (     

Uptake and distribution of abscisic acid in Commelina leaf epidermis

Closure of stomata by abscisic acid (ABA) was studied by floating leaf epidermal strips of Commelina communis L. in PIPES buffer (pH 6.8) containing a range of KCl concentrations. Control apertures were greatest at high concentrations of the salt, and the effects of ABA, in terms of closure, were most pronounced below 100 mol m^-3 KCl. Stomata opened on strips floated on buffer plus 50 mol m^-3 KCl and closed within 10 min when transferred to the same medium plus 0.1 mol m^-3 ABA. [2-¹⁴C]ABA was used to study uptake and distribution of the hormone by the epidermal strips. It was calculated that no more than 6 fmol ABA were present per stomatal complex at the time of closure, although uptake continued thereafter. Microautoradiography indicated that radioactivity from [2-¹⁴C]ABA accumulated in the stomatal complex at or near the guard cells within 20 min. TLC was used to examine the state of the label after 1 h incubation. Efflux of label from preincubated tissue appeared to occur in three phases (t_1/2=7.2 s, 4.0 min, 35.2 min). Efflux was correlated with stomatal re-opening. The results confirm that ABA can accumulate in the epidermis of C. communis.Abbreviation ABA Abscisic acid     

ParA encoded on chromosome II of Deinococcus radiodurans binds to nucleoid and inhibits cell division in Escherichia coli

Bacterial genome segregation and cell division has been studied mostly in bacteria harbouring single circular chromosome and low-copy plasmids. Deinococcus radiodurans, a radiation-resistant bacterium, harbours multipartite genome system. Chromosome I encodes majority of the functions required for normal growth while other replicons encode mostly the proteins involved in secondary functions. Here, we report the characterization of putative P-loop ATPase (ParA2) encoded on chromosome II of D. radiodurans. Recombinant ParA2 was found to be a DNA-binding ATPase. E. coli cells expressing ParA2 showed cell division inhibition and mislocalization of FtsZ-YFP and those expressing ParA2-CFP showed multiple CFP foci formation on the nucleoid. Although, in trans expression of ParA2 failed to complement SlmA loss per se, it could induce unequal cell division in slmAminCDE double mutant. These results suggested that ParA2 is a nucleoid-binding protein, which could inhibits cell division in E. coli by affecting the correct localization of FtsZ and thereby cytokinesis. Helping slmAminCDE mutant to produce minicells, a phenotype associated with mutations in the ‘Min’ proteins, further indicated the possibility of ParA2 regulating cell division by bringing nucleoid compaction at the vicinity of septum growth.     

Aerobic training increases the expression of adiponectin receptor genes in the peripheral blood mononuclear cells of young men

Little is known about the effect of exercise training on the expression of adiponectin receptor genes in peripheral blood mononuclear cells (PBMCs). In this study, we investigated the effects of aerobic training on the expression of AdipoR1 and AidpoR2 mRNAs in PBMCs, whole body insulin sensitivity, and circulating adiponectins in men. Thirty young men were randomly assigned to either a control (n=15) or an exercise (n=15) group. Subjects assigned to the exercise group underwent a 12-week jogging and/or running programme on a motor-driven treadmill at an intensity of 60%-75% of the age-based maximum heart rate with duration of 40 minutes per session and a frequency of 5 days per week. Two-way mixed ANOVA with repeated measures was used to test any significant time-by-group interaction effects for the measured variables at p=0.05. We found significant time-by-group interaction effects for waist circumference (p=0.001), VO_2max (p<0.001), fasting insulin (p=0.016), homeostasis model assessment for insulin resistance (HOMA-IR) (p=0.010), area under the curve (AUC) for insulin response during the 75-g oral glucose tolerance test (p=0.002), high-molecular weight (HMW) adiponectin (p=0.016), and the PBMC mRNA levels of AdipoR1 (p<0.001) and AdipoR2 (p=0.001). The exercise group had significantly increased mRNA levels of AdipoR1 and AdipoR2 in PBMCs, along with increased whole body insulin sensitivity and HMW adiponectin, decreased waist circumference, and increased VO_2max compared with the control group. In summary, the current findings suggest that exercise training modulates the expression of AdipoR1 and AdipoR2 mRNAs in PBMCs, implying that manipulation of the expression of these genes could be a potential surrogate for lifestyle intervention-mediated improvements of whole body insulin sensitivity and glucose homeostasis.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Extraktion von Ochratoxin A aus geröstetem Kaffee Mittels Accelerated Solvent Extraction (ASE)

Accelerated solvent extraction (ASE) is an alternative sample extraction procedure for ochratoxin A in roasted coffee. ASE results are comparable to that of the modified Koch method, but required less sample preparation time. Furthermore, ASE gave higher quantitative values than other methods reported for extraction of ochratoxin A. In the end less harmful water could be used for extraction.     

Volume changes of Commelina communis guard cell protoplasts in response to K+, light and CO2

The effects of K⁺ concentration, light intensity and CO₂ levels on the volume of Commelina communis L. guard cell protoplasts were studied. Two degrees of swelling response were observed, both dependent on an external supply of K⁺, but not necessarily on the supply of a permeant anion. The presence of K⁺ itself, independent of light or CO₂ level, stimulated swelling at a relatively slow rate. When K⁺, light and low CO₂ conditions were supplied together, the swelling was relatively rapid and of high magnitude. The rapid swelling was specific for K⁺ and Rb⁺ giving a half maximal effect after 2 h at a KCl concentration of about 18 mmol m⁻³. The addition of CaCl₂ at 1 mol m⁻³ inhibited K⁺-dependent swelling under all conditions tested. The response to light and low CO₂ levels by Commelina guard cell protoplasts is thought to reflect a high degree of physiological integrity.