[Research advances in the response of soil nitrogen emissions from peatlands to climate warming and drying]. / æ³¥ç‚­åœ°åœŸå£¤æ°®æŽ’æ”¾å¯¹æ°”å€™æš–å¹²åŒ–å“åº”ç ”ç©¶è¿›å±•.

Climate warming and drying has led to a sharp increase in nitrogen (N) emissions from the boreal peatland soils, but the underlying microbial-mediated mechanism is still unclear. We reviewed the responses of soil N transformation and emission in alpine peatland to temperature increases and water table changes, the interaction between soil anaerobic ammonia oxidation (Anammox) and NO3- dissimilatory reduction processes, and soil N2O production pathways and their contributions. There are several knowledge gaps. First, the amount of N loss in peatlands in alpine areas is seriously underestimated because most studies focused only on soil N2O emissions and ignored the release of N2. Second, the contribution of Anammox process to N2 emissions from peatlands is not quantified. Third, there is a lack of quantification of the relative contributions of Anammox, bacterial denitrification, and fungal co-denitrification processes to N2 loss. Finally, the decoupling mechanism of Anammox and NO3- reduction processes under a warming and drying climate scenario is not clear. Considering aforementioned shortages in previous studies, we proposed the directions and contents for future research. Through building an experimental platform with field warming and water level controlling, combining stable isotope, molecular biology, and metagenomics technology, the magnitude, composition ratio and main controlling factors of N emissions (N2O, NO, and N2) in boreal peatlands should be systematically investigated. The interaction among the main N loss processes in soils as well as the relative contributions of nitrification, anaerobic ammonia oxidation, and denitrification to N2O and N2 productions should be investigated and quantified. Furthermore, the sensitive microbial groups and the coupling between soil N transformations and microbial community succession should be clarified to reveal the microbiological mechanism underlying the responses of soil N turnover process to climate warming and drying.

Association between household size and risk of incident dementia in the UK Biobank study.

Currently, the relationship between household size and incident dementia, along with the underlying neurobiological mechanisms, remains unclear. This prospective cohort study was based on UK Biobank participants aged ≥ 50 years without a history of dementia. The linear and non-linear longitudinal association was assessed using Cox proportional hazards regression and restricted cubic spline models. Additionally, the potential mechanisms driven by brain structures were investigated by linear regression models. We included 275,629 participants (mean age at baseline 60.45 years [SD 5.39]). Over a mean follow-up of 9.5 years, 6031 individuals developed all-cause dementia. Multivariable analyses revealed that smaller household size was associated with an increased risk of all-cause dementia (HR, 1.06; 95% CI 1.02-1.09), vascular dementia (HR, 1.08; 95% CI 1.01-1.15), and non-Alzheimer's disease non-vascular dementia (HR, 1.09; 95% CI 1.03-1.14). No significant association was observed for Alzheimer's disease. Restricted cubic splines demonstrated a reversed J-shaped relationship between household size and all-cause and cause-specific dementia. Additionally, substantial associations existed between household size and brain structures. Our findings suggest that small household size is a risk factor for dementia. Additionally, brain structural differences related to household size support these associations. Household size may thus be a potential modifiable risk factor for dementia.

A newly isolated Rhizopus microsporus var. chinensis capable to secrete amyloltic enzymes with raw-starch-digesting activity.

A newly isolated active producer of raw starch digesting amyloltic enzymes, Rhizopus microsporus var. chinensis CICIM-CU F0088 was screened and identified by morphological characteristics and molecular phylogenetic analysis. This fungus was isolated from the soil of Chinese glue pudding mill, and produced high levels of amylolytic activity under solid state fermentation with supplementation of starch and wheat bran. Results of thin layer chromatography showed there are two kinds of amyloltic enzymes formed by this strain, including one alpha-amylase and two glucoamylases. It was found that the two glucoamylases can digest raw corn starch in the electron microscope experiments, and has an optimal temperature of 70 degrees Celsius. These results signified that amyloltic enzymes secreted by strain of Rhizopus microsporus var. chinensis CICIM-CU F0088 were kinds of thermostable amyloltic enzymes and able to digest raw corn starch.