The secondary outbreak risk and mechanisms of Microcystis aeruginosa after H2O2 treatment.

The secondary outbreak of cyanobacteria after algicide treatment has been a serious problem to water ecosystems. Hydrogen peroxide (H2O2) is an algaecide widely used in practice, but similar re-bloom problems are inevitably encountered. Our work found that Microcystis aeruginosa (M. aeruginosa) temporarily hibernates after H2O2 treatment, but there is still a risk of secondary outbreaks. Interestingly, the dormant period was as long as 20 and 28 days in 5 mg L-1 and 20 mg L-1 H2O2 treatment groups, respectively, but the photosynthetic activity was both restored much earlier (within 14 days). Subsequently, a quantitative imaging flow cytometry-based method was constructed and confirmed that the re-bloom had undergone two stages including first recovery and then re-division. The expression of ftsZ and fabZ genes showed that M. aeruginosa had active transcription processes related to cell division protein and fatty acid synthesis during the dormancy stat. Furthermore, metabolomics suggested that the recovery of M. aeruginosa was mainly by activating folate and salicylic acid synthesis pathways, which promoted environmental stress resistance, DNA synthesis, and cell membrane repair. This study reported the comprehensive mechanisms of secondary outbreak of M. aeruginosa after H2O2 treatment. The findings suggest that optimizing the dosage and frequency of H2O2, as well as exploring the potential use of salicylic acid and folic acid inhibitors, could be promising directions for future algal control strategies.

Solar/periodate-triggered rapid inactivation of Microcystis aeruginosa by interrupting the Calvin-Benson cycle.

Frequent outbreak of cyanobacteria is a serious problem for drinking water treatment. The microcystins released from Microcystis aeruginosa (M. aeruginosa) could cause irreversible damage to human health. Catalyst-free solar/periodate (PI) system has recently presented great potential for bacterial inactivation, whereas the application potential and underlying mechanisms of the effective M. aeruginosa control remain unclear. Our work delineated the key role of ROS that inactivating/harmless disposing M. aeruginosa in the simulated sunlight (SSL)/PI system. Singlet oxygen may specifically cause DNA damage but maintain membrane integrity, preventing the risk of microcystins leakage. The SSL/PI 300 µM system could also effectively inhibit M. aeruginosa recovery for >7 days and completely degrade microcystin-LR (50.0 µg/L) within 30 min. Non-targeted metabolomic analysis suggested that the SSL/PI system inactivated M. aeruginosa mainly by interrupting the Calvin-Benson cycle, which damaged the metabolic flux of glycolysis and its downstream pathways such as the oxidative PPP pathway and glutathione metabolism. Furthermore, the activated PI system exhibited an even better algal inhibition under natural sunlight irradiation, evidenced by the seriously damaged cell membrane of M. aeruginosa. Overall, this study reported the comprehensive mechanisms of algal control and application potentials of solar/PI systems. The findings facilitated the development of emerging algicidal technology and its application in controlling environmental harmful algae.

Uncovering novel disinfection mechanisms of solar light/periodate system: The dominance of singlet oxygen and metabolomic insights.

Disinfection plays an essential role in waterborne pathogen control and disease prevention, especially during the COVID-19 pandemic. Catalyst-free solar light/periodate (PI) system has recently presented great potential in water disinfection, whereas the in-depth chemical and microbiological mechanisms for efficient bacterial inactivation remain unclear. Our work delineated firstly the critical role of singlet oxygen, instead of reported hydroxyl radicals and superoxide radicals, in dominating bacterial inactivation by the PI/simulated sunlight (SSL) system. Multi-evidence demonstrated the prominent disinfection performance of this system for Staphylococcus aureus in terms of culturability (> 6 logs CFU), cellular integrity, and metabolic activity. Particularly, the excellent intracellular DNA removal (> 95%) indicated that PI/SSL system may function as a selective disinfection strategy to diminish bacterial culturability without damaging the cell membrane. The PI/SSL system could also effectively inhibit bacterial regrowth for > 5 days and horizontal gene transfer between E. coli genera. Nontargeted metabolomic analysis suggested that PI/SSL system inactivated bacteria by triggering the accumulation of intracellular reactive oxygen species and the depletion of reduced glutathione. Additionally, the PI/SSL system could accomplish simultaneous micropollutant removal and bacterial inactivation, suggesting its versatility in water decontamination. Overall, this study deciphers more comprehensive antibacterial mechanisms of this environmentally friendly disinfection system, facilitating the technical development and application of the selective disinfection strategy in environmental pathogen control.

Optimization of the extract from flower of Citrus aurantium L. var. amara Engl. and its inhibition of lipid accumulation.

Flower of Citrus aurantium L. var. amara Engl. (CAVA) has been confirmed to have promising anti-obesity effects. However, the regulation of alkaloid extracts from flower of CAVA (Al) on lipid metabolism remain unknown. In this study, Al was optimized by ultrasound-assisted extraction using response surface methodology. The optimal conditions were ultrasonic time 72 min, ethanol concentration 78% and liquid/solid ratio 30 ml/g with the maximum alkaloid yield 5.66%. LC-MS assay indicated that the alkaloid compounds were enriched in Al after optimization. Nine alkaloid compounds were identified in Al by LC-MS assay and stachydrine, caffeine and cathine appeared as the major alkaloid compounds. Bioactivity assay showed that Al treatment significantly increased superoxide dismutase (SOD) activity, and reduced malonaldehyde (MDA) and reactive oxygen species (ROS) levels. Al administration also reversed oleic acid-induced hepatic steatosis in Hep G2 cells by inhibiting the expression of lipogenesis-signaling genes including fatty acid synthase (FAS), peroxisome proliferator-activated receptor subtype γ (PPARγ), uncoupling protein 2 (UCP2), and retinol binding protein (RBP4). However, OA-induced reduction of lipolysis-related gene carnitine palmitoyl transferase 1A (CPT1A) in Hep G2 cells was not improved by Al supplementation. Moreover, the increased SOD activity and decreased MDA and ROS contents were also observed in Caenorhabditis elegans by Al addition. Al intervention exhibited the ability to inhibit lipid accumulation in C. elegans by suppressing expression of lipid metabolism-related genes. These results suggested that the alkaloid extracts from the flower of CAVA showed great potential to regulate lipid metabolism. PRACTICAL APPLICATIONS: The extraction of alkaloid extracts from the flower of CAVA was optimized with a maximum yield of 5.66%. The regulatory effects and mechanisms of Al on lipid metabolism of Hep G2 cells and Caenorhabditis elegans were also investigated. More clinical studies are required to evaluate the potential of using alkaloids from the flower of CAVA as therapeutic agents against lipid metabolic disorders.

Osteopontin's colocalization with the adhesion molecule CEACAM5 in cytoplasm of carcinoma of tongue and its correlation with the invasion of that diease.

The purpose of this study was to investigate the expression of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and correlate it with OPN expression and function in squamous carcinoma of tongue.Paraffin were sections of 80 samples with squamous carcinoma of tongue and 40 samples with normal tissue of tongue for benign lesion having undergone surgery. Immunohistochemistry (IHC) was used to study the distribution of CEACAM5 and OPN, and double-labeling immunohistochemistry was used to observe the relationship between CEACAM5 and OPN expression.CEACAM5 and OPN are found in normal tissue of tongue, but with different expression pattern. CEACAM5 expression mainly with membranous staining is restricted on the superficial epithelium. However, OPN expression with mainly cytoplasmic staining is restricted on the deep epithelium. No colocalization of CEACAM5 and OPN have been observed in normal tissue of tongue. In squamous carcinoma of tongue, CEACAM5 expression with cytoplasmic staining is different from normal tongue tissue with membranous staining, and the transformation of CEACAM5 distribution from membrane to cytoplasm is an important incident for the invasion and differentiation of tumor. CEACAM5 and OPN are colocalized in cytoplasm, and a significant correlation was observed between the positive colocalization and the negative colocalization in the depth of invasion and the differentiation of the tumor.