Wildfires correlate with reductions in aboveground tree carbon stocks and sequestration capacity on forest land in the Western United States.

In the United States (US), forest ecosystems are the largest terrestrial carbon sink, offsetting the equivalent of >12 % of economy-wide greenhouse gas (GHG) emissions annually. In the Western US, wildfires have shaped much of the landscape by changing forest structure and composition, increasing tree mortality, impacting forest regeneration, and influencing forest carbon storage and sequestration capacity. Here, we used remeasurements of >25,000 plots from the US Department of Agriculture, Forest Service Forest Inventory and Analysis (FIA) program and auxiliary information (e.g., Monitoring Trends in Burn Severity) to characterize the role of fire along with other natural and anthropogenic drivers on estimates of carbon stocks, stock changes, and sequestration capacity on forest land in the Western US. Several biotic (e.g., tree size, species, and forest structure) and abiotic factors (e.g., warm climate, severe drought, compound disturbances, and anthropogenic interventions) influenced post-fire tree mortality and regeneration and had concomitant impacts on carbon stocks and sequestration capacity. Forest ecosystems in a high severity and low frequency wildfire regime had greater reductions in aboveground biomass carbon stocks and sequestration capacity compared to forests in a low severity and high frequency fire regime. Results from this study can improve our understanding of the role of wildfire along with other biotic and abiotic drivers on carbon dynamics in forest ecosystems in the Western US.

Metformin promotes bacterial surface aggregation by inhibiting the swimming motility of flagellated Escherichia coli.

The antiglycemic drug metformin, which is widely prescribed as a first-line drug for the treatment of type 2 diabetes, has become a concern for emerging pollutants in natural ecosystems. However, its effects on bacterial swimming motility remain unclear. In this study, we showed that metformin promotes bacterial surface aggregation by tracking swimming and by measuring the density distribution of Escherichia coli cultured with metformin near a surface in a homogeneous environment. Flagella are essential for the promotion of bacterial surface aggregation by metformin. Swimming motility, which is mediated by flagella, determines bacterial surface aggregation. The promotion of bacterial surface aggregation by metformin is caused by a reduction in swimming motility, which is governed by a decrease in the proton motive force. Our results reveal that metformin has a pronounced effect on flagellated bacterial motility associated with surface sensing and aggregation.

Metformin Alters the Chemotaxis and Flagellar Motility of Escherichia coli.

Metformin is a biguanide molecule that is widely prescribed to treat type 2 diabetes and metabolic syndrome. Although it is known that metformin promotes the lifespan by altering intestinal microorganism metabolism, how metformin influences and alters the physiological behavior of microorganisms remains unclear. Here we studied the effect of metformin on the behavior alterations of the model organism Escherichia coli (E. coli), including changes in chemotaxis and flagellar motility that plays an important role in bacterial life. It was found that metformin was sensed as a repellent to E. coli by tsr chemoreceptors. Moreover, we investigated the chemotactic response of E. coli cultured with metformin to two typical attractants, glucose and α-methyl-DL-aspartate (MeAsp), finding that metformin prolonged the chemotactic recovery time to the attractants, followed by the recovery time increasing with the concentration of stimulus. Metformin also inhibited the flagellar motility of E. coli including the flagellar motor rotation and cell swimming. The inhibition was due to the reduction of torque generated by the flagellar motor. Our discovery that metformin alters the behavior of chemotaxis and flagellar motility of E. coli could provide potential implications for the effect of metformin on other microorganisms.

Farmers' Willingness to Participate in Agricultural Product Safety Cogovernance and Self-Governance in Jiangsu, China: A Gender Perspective.

ABSTRACT: Over the past two decades, the issues of quality and safety of agricultural products have attracted widespread attention in the People's Republic of China. The purpose of this study was to understand factors that influence farmers' willingness to participate in agricultural product safety cogovernance and self-governance based on a survey of farmers in Jiangsu Province, China. The results show that farmers' willingness to participate in the cogovernance and self-governance of agricultural product safety must be further improved. Among the sampled farmers, 28.93% consider that other farmers' improper agricultural product safety practices have nothing to do with them, and 17.25% claim that they would not want to take part in agricultural product safety trainings. Farmers with a weak appreciation for agricultural product safety hazards, a lack of food safety knowledge, and improper agricultural product safety practices are less willing to participate in cogovernance and self-governance of agricultural product safety. Female farmers are more willing to engage in agricultural product safety training than male farmers; however, their willingness to participate in agricultural product safety cogovernance is lower. The results of this study will be useful in improving food safety policy in China.