Falling bacterial communities from the atmosphere

Background Bacteria emitted into the atmosphere eventually settle to the pedosphere via sedimentation (dry deposition) or precipitation (wet deposition), constituting a part of the global cycling of substances on Earth, including the water cycle. In this study, we aim to investigate the taxonomic compositions and flux densities of bacterial deposition, for which little is known regarding the relative contributions of each mode of atmospheric deposition, the taxonomic structures and memberships, and the aerodynamic properties in the atmosphere. Results Precipitation was found to dominate atmospheric bacterial deposition, contributing to 95% of the total flux density at our sampling site in Korea, while bacterial communities in precipitation were significantly different from those in sedimentation, in terms of both their structures and memberships. Large aerodynamic diameters of atmospheric bacteria were observed, with an annual mean of 8.84 μm, which appears to be related to their large sedimentation velocities, with an annual mean of 1.72 cm s− 1 for all bacterial taxa combined. The observed mean sedimentation velocity for atmospheric bacteria was larger than the previously reported mean sedimentation velocities for fungi and plants. Conclusions Large aerodynamic diameters of atmospheric bacteria, which are likely due to the aggregation and/or attachment to other larger particles, are thought to contribute to large sedimentation velocities, high efficiencies as cloud nuclei, and large amounts of precipitation of atmospheric bacteria. Moreover, the different microbiotas between precipitation and sedimentation might indicate specific bacterial involvement and/or selective bacterial growth in clouds. Overall, our findings add novel insight into how bacteria participate in atmospheric processes and material circulations, including hydrological circulation, on Earth.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (2013R1A1A1004497)

Pectin and high-amylose maize starch increase caecal hydrogen production and relieve hepatic ischaemia-reperfusion injury in rats.

We investigated whether the feeding of high H2-generating dietary fibre and resistant starch (RS) could suppress hepatic ischaemia-reperfusion (IR) injury, which results from oxidative stress, in rats fed a pectin (Pec) or high-amylose maize starch (HAS) diet. Male Sprague-Dawley rats were fed a control (C) diet, with or without Pec (0-5 % Pec) or HAS (0-30 % HAS) supplementation for 7 d. Portal H2 concentration showed a significant dose-dependent increase with the amount of Pec or HAS supplementation. Plasma alanine and aspartate aminotransferase activities remarkably increased in the C rats (5 % cellulose) due to IR treatment, while it decreased significantly or showed tendencies to decrease in 5 % Pec and 20 % HAS diet-fed rats. The hepatic oxidised glutathione (GSSG):total glutathione ratio increased significantly in IR rats maintained on the C diet compared with sham-operated rats. On the other hand, reduced glutathione (GSH):total glutathione and GSH:GSSG ratios decreased significantly. The GSSG:total glutathione ratio that increased due to IR treatment decreased significantly on HAS and Pec intake, while GSH:total glutathione and GSH:GSSG ratios increased significantly. Hepatic sinusoids of IR rats fed the C diet were occluded, but those of IR rats fed the Pec diet were similar to those in the sham-operated rats. In conclusion, we found that Pec or HAS, which enhance H2 generation in the large intestine, alleviated hepatic IR injury. The present study demonstrates another physiological significance of dietary fibre and RS.We investigated whether the feeding of high H2-generating dietary fibre and resistant starch (RS) could suppress hepatic ischaemia-reperfusion (IR) injury, which results from oxidative stress, in rats fed a pectin (Pec) or high-amylose maize starch (HAS) diet. Male Sprague-Dawley rats were fed a control (C) diet, with or without Pec (0-5 % Pec) or HAS (0-30 % HAS) supplementation for 7 d. Portal H2 concentration showed a significant dose-dependent increase with the amount of Pec or HAS supplementation. Plasma alanine and aspartate aminotransferase activities remarkably increased in the C rats (5 % cellulose) due to IR treatment, while it decreased significantly or showed tendencies to decrease in 5 % Pec and 20 % HAS diet-fed rats. The hepatic oxidised glutathione (GSSG):total glutathione ratio increased significantly in IR rats maintained on the C diet compared with sham-operated rats. On the other hand, reduced glutathione (GSH):total glutathione and GSH:GSSG ratios decreased significantly. The GSSG:total glutathione ratio that increased due to IR treatment decreased significantly on HAS and Pec intake, while GSH:total glutathione and GSH:GSSG ratios increased significantly. Hepatic sinusoids of IR rats fed the C diet were occluded, but those of IR rats fed the Pec diet were similar to those in the sham-operated rats. In conclusion, we found that Pec or HAS, which enhance H2 generation in the large intestine, alleviated hepatic IR injury. The present study demonstrates another physiological significance of dietary fibre and RS

Soil nematodes show a midelevation diversity maximum and elevational zonation on Mt. Norikura, Japan

Little is known about how nematode ecology differs across elevational gradients. We investigated the soil nematode community along a ~2,200 m elevational range on Mt. Norikura, Japan, by sequencing the 18S rRNA gene. As with many other groups of organisms, nematode diversity showed a high correlation with elevation, and a maximum in mid-elevations. While elevation itself, in the context of the mid domain effect, could predict the observed unimodal pattern of soil nematode communities along the elevational gradient, mean annual temperature and soil total nitrogen concentration were the best predictors of diversity. We also found nematode community composition showed strong elevational zonation, indicating that a high degree of ecological specialization that may exist in nematodes in relation to elevation-related environmental gradients and certain nematode OTUs had ranges extending across all elevations, and these generalized OTUs made up a greater proportion of the community at high elevations – such that high elevation nematode OTUs had broader elevational ranges on average, providing an example consistent to Rapoport’s elevational hypothesis. This study reveals the potential for using sequencing methods to investigate elevational gradients of small soil organisms, providing a method for rapid investigation of patterns without specialized knowledge in taxonomic identification

Reduced serum level of leukocyte cell-derived chemotaxin 2 is associated with the presence of diabetic retinopathy

AbstractBackgroundVascular endothelial growth factor (VEGF) signaling is an important pathway in the development of diabetic retinopathy (DR). A recent report showed that leukocyte cell-derived chemotaxin 2 (LECT2) suppresses the VEGF signaling in endothelial cells. However, the clinical relevance of LECT2 in DR is unknown. This study aimed to investigate serum LECT2 levels and the presence of DR.MethodsThe study included 230 people with type 2 diabetes mellitus (DM), 95 with DR and 135 without DR. Serum LECT2 levels were measured using an enzyme-linked immunosorbent assay. Data were evaluated using Spearman's rank correlation, univariate and multivariate logistic regression.ResultsSerum LECT2 levels were significantly lower in participants with DM having DR than in those not having DR (35.6±14.9ng/ml vs. 44.5±17.6ng/ml, P<0.001). Spearman's rank correlation analysis revealed a significant association between serum LECT2 levels and the presence of DR (P<0.001). Multiple regression analysis revealed that serum LECT2 levels were independently related to DR (P<0.001).ConclusionsThese findings indicated that serum LECT2 level is negatively associated with the presence of DR and suggest that low circulating LECT2 level is a risk factor for DR

​Rapid response to experimental warming of a microbial community inhabiting High Arctic patterned ground soil

The influence of climate change on microbial communities inhabiting the sparsely vegetated patterned ground soils that are widespread across the High Arctic is poorly understood. Here, in a four-year experiment on Svalbard, we warmed patterned ground soil with open top chambers and biannually irrigated the soil to predict the responses of its microbial community to rising temperatures and precipitation. A 1 °C rise in summertime soil temperature caused 44% and 78% increases in CO2 efflux and CH4 consumption, respectively, and a 32% increase in the frequency of bacterial 16S ribosomal RNA genes. Bacterial alpha diversity was unaffected by the treatments, but, of the 40 most frequent bacterial taxa, warming caused 44–45% reductions in the relative abundances of a Sphingomonas sp. and Ferruginibacter sp. and 33–91% increases in those of a Phenylobacterium sp. and a member of the Acetobacteraceae. Warming did not influence the frequency of fungal internal transcribed spacer 2 copies, and irrigation had no effects on the measured variables. Our study suggests rapid changes to the activities and abundances of microbes, and particularly bacteria, in High Arctic patterned ground soils as they warm. At current rates of soil warming on Svalbard (0.8 °C per decade), we anticipate that similar effects to those reported here will manifest themselves in the natural environment by approximately the mid 2030s

グラヤノトキシンD環の化学修飾

Grayanotoxin (GTX), one of the lipid-soluble Na+ channel openers, contains four rings (A, B, C and D) and the chemical groups essential for the pharmacological action are located on the A- and B-rings. To study the biological significance of functional groups on the D-ring, 51 new derivatives were prepared from α-dihydro GTX- 11 . These new compounds and the previously prepared GTXS ere directly applied to the intracellular phase of internally perfused squid giant axons

A Novel Methodology to Evaluate Health Impacts Caused by VOC Exposures Using Real-Time VOC and Holter Monitors

While various volatile organic compounds (VOCs) are known to show neurotoxic effects, the detailed mechanisms of the action of VOCs on the autonomic nervous system are not fully understood, partially because objective and quantitative measures to indicate neural abnormalities are still under development. Nevertheless, heart rate variability (HRV) has been recently proposed as an indicative measure of the autonomic effects. In this study, we used HRV as an indicative measure of the autonomic effrects to relate their values to the personal concentrations of VOCs measured by a real-time VOC monitor. The measurements were conducted for 24 hours on seven healthy subjects under usual daily life conditions. The results showed HF powers were significantly decreased for six subjects when the changes of total volatile organic compound (TVOC) concentrations were large, indicating a suppression of parasympathetic nervous activity induced by the exposure to VOCs. The present study indicated these real-time monitoring was useful to characterize the trends of VOC exposures and their effects on autonomic nervous system