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Rising ambient temperature is expected to increase incidence of bacillary dysentery (BD), but few studies have compared the temperature-BD effects of different age groups and cities in China, especially in a multi-city setting. We used city-specific data including BD cases and meteorological variables to determine the relationship between BD incidence and temperature at provincial level. Weekly BD disease surveillance data and meteorological variables were collected in all 16 prefecture-level cities in Anhui Province of China. Firstly, city-specific weekly mean temperature-BD incidence associations were estimated with Distributed Lag Nonlinear Model (DLNM). Secondly, city-specific estimates were pooled at province-level through multivariate meta-analysis. Also, we conducted subgroup analyses for ages (children <5 years old and population of other ages) and urbanization of cities (high and low level), respectively. In Anhui, BD morbidity risk increased with increasing weekly mean temperature. Relative risks (RR) at the 90th percentile (27.5 °C) versus the 50th percentile (17 °C) of weekly mean temperature were 1.42 (95% confidence interval (CI): 1.16, 1.75) and 2.02 (95% CI: 1.76, 2.32) for children <5 and population of other ages, respectively. The relative risk of high temperature on other ages group was higher than that of children under five years old (p = 0.006). Children under 5 in high urbanized cities appeared to be more vulnerable to the effects of ambient high temperature (RR: 1.56, 95% CI: 1.20, 1.92) than in low urbanized cities (RR: 1.01, 95% CI: 0.70, 1.46), the difference between two intervals was statistically significant (p = 0.044). This study suggests that high temperatures may be an important trigger of BD incidence, and especially lead to a substantial burden of BD for high urbanized cities in Anhui Province of China. Unlabelled Image • High weekly mean temperature increased risks of bacillary dysentery (BD) in Anhui. • Urbanization level modified associations between high temperature and BD incidence. • For children <5, effect of high temperature on BD increased in high urbanized cities. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation, conducted by soil diazotrophs, is the primary nitrogen source for natural grasslands. However, the diazotrophs in grassland soils are still far from fully investigated. Particularly, their regional-scale distribution patterns have never been systematically examined. Here, soils (0–5 cm) were sampled from 54 grasslands on the Tibetan Plateau to examine the diazotroph abundance, diversity, and community composition, as well as their distribution patterns and driving factors. The diazotroph abundance was expressed as nifH gene copies, measured using real-time PCR. The diversity and community composition of diazotrophs were analyzed through MiSeq sequencing of nifH genes. The results showed that Cyanobacteria (47.94%) and Proteobacteria (45.20%) dominated the soil diazotroph communities. Most Cyanobacteria were classified as Nostocales which are main components of biological crusts. Rhizobiales, most of which were identified as potential symbiotic diazotrophs, were also abundant in approximately half of the soil samples. The soil diazotroph abundance, diversity, and community composition followed the distribution patterns in line with mean annual precipitation. Moreover, they also showed significant correlations with prokaryotic abundance, plant biomass, vegetation cover, soil pH values, and soil nutrient contents. Among these environmental factors, the soil moisture, organic carbon, available phosphorus, and inorganic nitrogen contents could be the main drivers of diazotroph distribution due to their strong correlations with diazotroph indices. These findings suggest that autotrophic and symbiotic diazotrophs are the predominant nitrogen fixers in Tibetan grassland soils, and highlight the key roles of water and nutrient availability in determining the soil diazotroph distribution on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Grazing is expected to exert a substantial influence on antibiotic resistance genes (ARGs) in grassland ecosystems. However, the precise effects of grazing on the composition of ARGs in grassland soils remain unclear. This is especially the case for grassland soils subject to long-term grazing. Here, we investigated ARGs and bacterial community composition in soils subject to long-term historic grazing (13–39 years) and corresponding ungrazed samples. Using a combination of shotgun metagenomics, amplicon analyses and associated soil physicochemical data, we provide novel insights regarding the structure of ARGs in grassland soils. Interestingly, our analysis revealed that long-term historic grazing had no impacts on the composition of ARGs in grassland soils. An average of 378 ARGs, conferring resistance to 14 major categories of antibiotics (80%), were identified in both grazing and ungrazed sites. Actinobacteria , Proteobacteria and Acidobacteria were the most prevalent predicted hosts in these soils and were also shown to harbour genetic capacity for multiple-resistant ARGs. Our results suggested that positive effects of bacterial community composition on ARGs could potentially be controlled by affecting MGEs. Soil properties had direct effects on the composition of ARGs through affecting the frequency of horizontal gene transfer among bacteria. Twelve novel ARGs were found in S. grandis steppe grasslands, indicating that different vegetation types might induce shifts in soil ARGs. Collectively, these findings suggest that soil properties, plants and microorganisms play critical roles in shaping ARG patterns in grasslands. Together, these data establish a solid baseline for understanding environmental antibiotic resistance in grasslands. Unlabelled Image • ARGs related with resistance to cephalosporin and tetracycline were dominant. • ARGs driven by factors affecting the distribution of soil microorganisms in grasslands. • Long-term historic grazing had no effect on ARGs in grassland soils. • ARGs shaped by the initial plant, soil environmental parameters and microbiomes in grassland. [ABSTRACT FROM AUTHOR]