Promoting the denitrification process by heavy metals in Liaohe Estuary sediment.

The impact of heavy metal ions on the biodenitrification process remains unknown, which is the key to understand the nitrogen cycle in estuarine areas. Here, denitrification rate and the abundance of five denitrifying enzyme genes (narG, nirK, napA, norB and nosZ) in Liaohe Estuary sediments were examined, and the community structure of nirK denitrifying bacteria was also analyzed. The results demonstrate a significant positive correlation between heavy metal content (Cu2+, Zn2+, and Cr) and the denitrification rate, and the abundance of napA/norB (periplasmic nitrate reductase and nitric-oxide reductase) in sediments. The dominant narG denitrifiers were Pseudomonas, Hydrogenophaga, and Serratia known to be tolerant to heavy metal pollution. Sediment particle size, NO3-, NO2-, Zn2+, and Cd2+ were the key factors influencing the denitrifying community structure. These findings suggest that heavy metals may enhance the aerobic denitrification process in sediments and mitigate the adverse effects of high dissolved oxygen levels.

Full-length 16S rRNA gene sequencing reveals spatiotemporal dynamics of bacterial community in a heavily polluted estuary, China.

Understanding the bacterial community structure of the river estuary could provide insights into the resident microorganisms in response to environmental pollution. In this study, the bacterial community structure of Liaohe Estuary was investigated using single-molecule real-time sequencing (SMRT). A total of 57 samples were collected and grouped according to habitat, space, season, and lifestyle. In seawater, regardless of whether it is particle-attached (PA) or free-living (FL) bacteria, the area with higher alpha diversity is the nearshore area in the dry season, while it is the midstream area in the wet season. The bacterial communities in sediment and seawater samples were different at the genus level in the nearshore area, and habitat type was the main factor. A marked difference in the bacterial community was observed in the dry season between different lifestyles but not in the wet season, which resulted from lifestyle transitions of bacterioplankton. Bacterial community varied spatially but not seasonally in sediment samples. In seawater, both FL and PA bacterial communities varied spatially during the wet season. Seasonal differences were only observed in FL bacterial community. Zn and sand were the principal determining factors of the bacterial community in the sediment, Cu and salinity were the main environmental factors for FL bacteria, and Cu, salinity, Zn and temperature were the main environmental factors for PA bacteria. Besides, the tide and nutrients were also the main drivers of the bacterial community in seawater. The indicative taxa, related to Cyanobium_PCC-6307, Pseudomonas and Vibrio, further evidenced the presence of possible bloom, crude oil and pathogen contamination. Overall, our results can contribute to the knowledge of the bacterial community and anthropogenic impacts on the Liaohe Estuary.

Dihydroergocriptine increase levels of cAMP and adenylyl cyclase in hippocampus of mice with vascular dementia / 基础医学与临床

Objective To observe the levels of cAMP and adenylyl cyclase(AC) in hippocampus of mice with vascular dementia(VD) and the effect of Dihydroergocriptine(DHE),and to explore the molecular pathogenesis of VD.Methods The mice were subjected for ischemia-reperfusion three times on bilateral common carotid arteries by knots to establish models of VD and the changes of learning and memory were tested on d29/d30 after operation.DHE was administrated to another group of mice,which was taken as treatment group.The cAMP level was evaluated by the radioimmunoassay;AC mRNA positive neurons of hippocampus CA1 area were examined through in-situ hybridization.Results Compared with shamed-operation group,the learning and memory of model group was worse(P

Effects of Hydergine on expression of N-methyl-D-aspartate receptors in hippocampus and actions of mice with ischemia-reperfusion injury / 临床神经病学杂志

Objective To study the effects of Hydergine on expression of N-methyl-D-aspartate receptors in hippocampus and actions of mice with ischemia-reperfusion injury.Methods 36 mice were randomly divided into model group,Hydergine group and sham-operated group. The models of ischemia-reperfusion injury were made by knotting bilateral common carotid arteries. The behavioral abnormalities were investigated by step-down test and water maze test, and the expressions of N-methyl-D-aspartate receptors in neurons of hippocampus were observed by immunohistochemistry technique. Results Compared with model group, the performance records of learning and memory in Hydergine group were better (all P