Simultaneous ammonium and sulfate biotransformation driven by aeration: Nitrogen/sulfur metabolism and metagenome-based microbial ecology.

The present study aimed to clarify the effect of oxygen respiration on biotransformation of alternative electron acceptors (e.g., nitrate and sulfate) underlying the simultaneous removal of ammonium and sulfate in a single aerated sequencing batch reactor. Complete nitrification was achieved in feast condition, while denitrification was carried out in both feast and famine conditions when aeration intensity (AI) was higher than 0.22 L/(L·min). Reactors R1 [0.56 L/(L·min)], R2 [0.22 L/(L·min)], and R3 [0.08 L/(L·min)] achieved 72.39% sulfate removal efficiency in feast condition, but H2S release occurred in R3. Following exogenous substrate depletion, sulfate concentration increased again and exceeded the influent value in R1, indicating that sulfate transformation was affected by oxygen intrusion. Metagenomic analysis showed that a higher AI promoted sulfate reduction by switching from dissimilatory to assimilatory pathway. Lower AI-acclimated microorganisms (R3) produced H2S and ammonium, while higher AI-acclimated microorganisms (R1) accumulated nitrite, which confirmed that biotransformation of N and S was strongly regulated by redox imbalance driven by aeration. This implied that respiration control, a microbial self-regulation mechanism, was linked to the dynamic imbalance between electron donors and electron acceptors. Aerobic nitrate (sulfate) reduction, as one of the effects of respiration control, could be used as an alternative strategy to compensate for dynamic imbalance, when supported by efficient endogenous metabolism. Moderate aeration induced microorganisms to change their energy conservation and survival strategy through respiration control and inter-genus protection of respiratory activity among keystone taxa (including Azoarcus in R1, Thauera in R2, and Thiobacillus, Ottowia, and Geoalkalibacter in R3) to form an optimal niche in response to oxygen intrusion and achieve benign biotransformation of C, N, and S without toxic intermediate accumulation. This study clarified the biotransformation mechanism of ammonium and sulfate driven by aeration and provided theoretical guidance for optimizing existing aeration-based techniques.

Comparison of myocardial ischemic/hypoxic staining techniques for evaluating the alleviation of exhaustive exercise-induced myocardial injury by exercise preconditioning.

Exercise preconditioning (EP) can alleviate myocardial ischemic/hypoxic injury by inducing endogenous cardioprotection. Hematoxylin-eosin (HE), hematoxylin-basic fuchsin-picric acid (HBFP), and chromotrope-2R brilliant green (C-2R BG) staining have been used to visualize myocardial ischemic/hypoxic changes in previous EP studies, but comprehensive evaluation and comparisons of these methods are lacking. This study evaluated ischemic/hypoxic changes in adjacent myocardial sections by HE, HBFP, and C-2R BG and compared the characteristics of sections stained by these three methods to show changes associated with exercise-induced myocardial ischemic/hypoxic injury. Rats were randomly divided into four groups: control (C), exercise preconditioning (EP), exhaustive exercise (EE), and exercise preconditioning + exhaustive exercise (EP + EE). Adjacent myocardial sections were stained as described above and compared to evaluate the effects of exercise-induced myocardial ischemic/hypoxic injury. The three staining methods revealed consistent localization patterns of myocardial ischemic/hypoxic injury in all groups. Results suggest that EP can alleviate exhaustive exercise-induced myocardial ischemic/hypoxic injury, and the three staining methods are suitable for the histological study of exercise-induced myocardial ischemic/hypoxic injury and protection. HE staining is a simple procedure but is not specific for myocardial ischemic/hypoxic injury. HBFP and C-2R BG staining can be used to specifically visualize myocardial ischemic/hypoxic injury.

Comprehensive performance, bacterial community structure of single-chamber microbial fuel cell affected by COD/N ratio and physiological stratifications in cathode biofilm.

This study compares the effects and bacterial community structure of single-chamber microbial fuel cells (MFCs) in the treatment of NH4+-containing wastewater with different chemical oxygen demand (COD)/N ratios, whilst simultaneously conducting stratification research on the cathode biofilm. To this end, five nitrifier pre-enriched single-chamber MFC reactors are established to treat five different COD/N wastewaters, respectively. The results show that MFCs with low COD/N have better NH4+-N removal, electrochemical performance, but the removal stability and COD removal effect are lower than MFCs with high COD/N. High-throughput sequencing reveals that the anode community structure is weakly affected by the COD/N and is dominated by Geobacter; however, the cathode community is complex and susceptible to the COD/N. Furthermore, the pH profile in the cathode biofilm is characterized by a pH microelectrode and fluorescence in situ hybridization (FISH) is used to confirm that the distribution trend of nitrifiers and denitrifiers in cathode biofilm.

Characteristics of microbial denitrification under different aeration intensities: Performance, mechanism, and co-occurrence network.

This study aimed to explore how dissolved oxygen (DO) affected the characteristics and mechanisms of denitrification in mixed bacterial consortia. We analyzed denitrification efficiency, intracellular nicotinamide adenine dinucleotide (NADH), relative expression of functional genes, and potential co-occurrence network of microorganisms. Results showed that the total nitrogen (TN) removal rates at different aeration intensities (0.00, 0.25, 0.63, and 1.25 L/(L·min)) were 0.93, 1.45, 0.86, and 0.53 mg/(L·min), respectively, which were higher than previously reported values for pure culture. The optimal aeration intensity was 0.25 L/(L·min), at which the maximum NADH accumulation rate and highest relative abundance of napA, nirK, and nosZ were achieved. With increased aeration intensity, the amount of electron flux to nitrate decreased and nitrate assimilation increased. On one hand, nitrate reduction was primarily inhibited by oxygen through competition for electron donors of a certain single strain. On the other hand, oxygen was consumed rapidly by bacteria by stimulating carbon metabolism to create an optimal denitrification niche for denitrifying microorganisms. Denitrification was performed via inter-genus cooperation (competitive interactions and symbiotic relationships) between keystone taxa (Azoarcus, Paracoccus, Thauera, Stappia, and Pseudomonas) and other heterotrophic bacteria (OHB) in aeration reactors. However, in the non-aeration case, which was primarily carried out based on intra-genus syntrophy within genus Propionivibrio, the co-occurrence network constructed the optimal niche contributing to the high TN removal efficiency. Overall, this study enhanced our knowledge about the molecular ecological mechanisms of aerobic denitrification in mixed bacterial consortia and has theoretical guiding significance for further practical application.

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus.

The most important and broad-spectrum drug used to control the parasitic worms to date is ivermectin (IVM). Resistance against IVM has emerged in parasites, and preserving its efficacy is now becoming a serious issue. The parasitic nematode Haemonchus contortus (Rudolphi, 1803) is economically an important parasite of small ruminants across the globe, which has a successful track record in IVM resistance. There are growing evidences regarding the multigenic nature of IVM resistance, and although some genes have been proposed as candidates of IVM resistance using lower magnification of genome, the genetic basis of IVM resistance still remains poorly resolved. Using the full magnification of genome, we herein applied a population genomics approach to characterize genome-wide signatures of selection among pooled worms from two susceptible and six ivermectin-resistant isolates of H. contortus, and revealed candidate genes under selection in relation to IVM resistance. These candidates also included a previously known IVM-resistance-associated candidate gene HCON_00148840, glc-3. Finally, an RNA-interference-based functional validation assay revealed the HCON_00143950 as IVM-tolerance-associated gene in H. contortus. The possible role of this gene in IVM resistance could be detoxification of xenobiotic in phase I of xenobiotic metabolism. The results of this study further enhance our understanding on the IVM resistance and continue to provide further evidence in favor of multigenic nature of IVM resistance.

Altered expression levels of autophagy-associated proteins during exercise preconditioning indicate the involvement of autophagy in cardioprotection against exercise-induced myocardial injury.

Exercise has been reported to induce autophagy. We hypothesized that exercise preconditioning (EP)-related autophagy in cardiomyocytes could be attributed to intermittent ischemia-hypoxia, allowing the heart to be protected for subsequent high-intensity exercise (HE). We applied approaches, chromotrope-2R brilliant green (C-2R BG) staining and plasma cTnI levels measuring, to characterize two periods of cardioprotection after EP: early EP (EEP) and late EP (LEP). Further addressing the relationship between ischemia-hypoxia and autophagy, key proteins, Beclin1, LC3, Cathepsin D, and p62, were determined by immunohistochemical staining, western blotting, and by their adjacent slices with C-2R BG. Results indicated that exercise-induced ischemia-hypoxia is a key factor in Beclin1-dependent autophagy. High-intensity exercise was associated with the impairment of autophagy due to high levels of LC3II and unchanged levels of p62, intermittent ischemia-hypoxia by EP itself plays a key role in autophagy, which resulted in more favorable cellular effects during EEP-cardioprotection compared to LEP.

Simultaneous removal of nitric oxide and sulfur dioxide in a biofilter under micro-oxygen thermophilic conditions: Removal performance, competitive relationship and bacterial community structure.

The efficiency of a biofilter to simultaneously remove nitric oxide (NO) and sulfur dioxide (SO2) was investigated under thermophilic (48 ±â€¯2 °C) micro-oxygen (3 vol%) conditions. After the start-up stage (Days 0-14), the stable operation period was divided into three stages. SO2 inlet concentration remained 500 mg/m3, NO inlet concentrations were 300 mg/m3 (Days 15-40), 500 mg/m3 (Days 41-70) and 700 mg/m3 (Days 71-100). In each stable stage, the removal efficiency of NO and SO2 exceeded 90%, the maximum removal rates of NO and SO2 were 98.08% and 99.61%, respectively. The final products of SO2 were mostly sulphur. Nitrate-reducing bacteria inhibited sulphate-reducing bacteria. Illumina high-throughput sequencing confirmed that the relative abundance of nitrate-reducing bacteria was positively correlated with NO removal efficiency, the relative abundance of sulphate-reducing bacteria was related to the conversion rate of sulphur.

Effects of 2,4,6-trichlorophenol on simultaneous nitrification and denitrification: Performance, possible degradation pathway and bacterial community structure.

This study aimed to investigate the effect of different 2,4,6-trichlorophenol (TCP) concentrations on the performance of simultaneous nitrification and denitrification processes established in a sequential batch biofilm reactor. And the degradation and the possible degradation pathway of 2,4,6-TCP and microbial community structure were also explored. Results indicated that 2,4,6-TCP inhibited the nitrification with the decrease in ammonium nitrogen removal. However, 2,4,6-TCP had different effects on denitrification. Nitrate accumulation showed the tendency to decrease first and then increase, whilst nitrite accumulation showed the opposite with a small change. The adaptation and recovery time of 25 mg/l 2,4,6-TCP was longest. In addition, the process had a good degradation effect on 2,4,6-TCP. Comparing the degradation of 2,4,6-TCP under different concentrations, the result showed that 2,4,6-TCP was mainly reduced to 2,4-dichlorophenol. With the increase in 2,4,6-TCP concentration, the differences in the bacterial community in the reactor were significant.

Effects of exercise on behavior and peripheral blood lymphocyte apoptosis in a rat model of chronic fatigue syndrome.

This study examined the effects of exercise on behavior and peripheral blood leukocyte apoptosis in a rat model of chronic fatigue syndrome (CFS). Thirty-six healthy male Sprague-Dawley rats were equally randomized into 3 groups: the control group, CFS model group and the exercise group in terms of body weight. A total of 25 rats entered the final statistical analysis due to 11 deaths during the study. CFS model was established by subjecting the rats in CFS model group and exercise group to electric shock, chronic restraint stress and cold water swim. Besides, rats in the exercise group took running wheel exercise. After a week of conditioning feeding, model construction and running wheel exercise were performed simultaneously, and lasted for 23 consecutive days. The behavior experiments, including running wheel exercise, open-field test, tail suspension test and Morris water maze test, were conducted, either before or after the model establishment. Rats were sacrificed and peripheral blood was obtained for the assessment of lymphocyte apoptosis index by flow cytometry (FCM). It was found that as compared with those in the control group, the weight of the rats was decreased obviously (P<0.01), the mobility time in the open-field and the tail suspension tests was shortened significantly (P<0.01), the time to locate the platform was enhanced (P<0.01) and the cell apoptosis index was increased substantially (P<0.01) in the CSF model group. Meanwhile, in comparison to the model group, the behavior in the open-field and the tail suspension tests was improved significantly (P<0.05), and the apoptosis index decreased remarkably (P<0.01) in the exercise group. It is concluded that sport intervention can prevent lymphocyte apoptosis and improve animal behavior rather than the memory.

Effects of Exercise on Behavior and Peripheral Blood Lymphocyte Apoptosis in a Rat Model of Chronic Fatigue Syndrome / 华中科技大学学报（医学）（英德文版）

This study examined the effects of exercise on behavior and peripheral blood leukocyte apoptosis in a rat model of chronic fatigue syndrome(CFS).Thirty-six healthy male Sprague-Dawley rats were equally randomized into 3 groups: the control group,CFS model group and the exercise group in terms of body weight.A total of 25 rats entered the final statistical analysis due to 11 deaths during the study.CFS model was established by subjecting the rats in CFS model group and exercise group to electric shock,chronic restraint stress and cold water swim.Besides,rats in the exercise group took running wheel exercise.After a week of conditioning feeding,model construction and running wheel exercise were performed simultaneously,and lasted for 23 consecutive days.The behavior experiments,including running wheel exercise,open-field test,tail suspension test and Morris water maze test,were conducted,either before or after the model establishment.Rats were sacrificed and peripheral blood was obtained for the assessment of lymphocyte apoptosis index by flow cytometry(FCM).It was found that as compared with those in the control group,the weight of the rats was decreased obviously(P<0.01),the mobility time in the open-field and the tail suspension tests was shortened significantly(P<0.01),the time to locate the platform was enhanced(P<0.01)and the cell apoptosis index was increased substantially(P<O.01)in the CSF model group.Meanwhile,in comparison to the model group,the behavior in the open-field and the tail suspension tests was improved significantly(P<0.05),and the apoptosis index decreased remarkably(P<0.01)in the exercise group.It is concluded that sport intervention can prevent lymphocyte apoptosis and improve animal behavior rather than the memory.