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• Rhizoma coptidis has a good inhibitory effect on Vibrio alginolyticus. • Transcriptomic analysis reveals the molecular mechanism of virulence genes. • Rhizoma coptidis could potnetially be a substitute for antibiotics. Rhizoma coptidis , a Chinese herbal medicine widely used to treat various bacterial infections, has the potential to develop antibiotic substitutes to overcome the drug resistance of Vibrio alginolyticus. To study the inhibitory effect of R. coptidis on V. alginolyticus , we sequenced the transcriptomes of three groups of samples of wild-type V. alginolyticus (CK) and V. alginolyticus , which were stressed by 5 mg/mL R. coptidis for 2 h (RC_2 h) and 4 h (RC_4 h). CK was compared with RC_2 h and RC_4 h, respectively, and a total of 1565 differentially expressed genes (DEGs) (988 up-regulated and 577 down-regulated) and 1737 DEGs (1152 up-regulated and 585 down-regulated) were identified. Comparing RC_2 h with RC_4 h, 156 DEGs (114 up-regulated and 42 down-regulated) were identified. The ability of biofilm formation and motility of V. alginolyticus altered upon with different concentrations of R. coptidis. Interestingly, relative expression patterns of virulence genes appeared statistically significantly varied, upon different concentrations of R. coptidis extract. DEGs were annotated to the Gene Ontology (GO) database for function enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the results showed that the main enriched pathways, was those related to the virulence of V. alginolyticus. This study provides a new perspective for understanding the complex pathogenic mechanism of V. alginolyticus. R. coptidis could potnetially be used as alternative or complimnetary to antibiotics to treat infections after further research. [ABSTRACT FROM AUTHOR]

• 1200 μg/mL F. schisandrae inhibited the growth of V.alginolyticus ND-01. • V. alginolyticus under high concentrations of F. schisandrae stress had insufficient ability in the whole biofilm formation process. • DEGs was involved in the following functional categories: metabolic process, single-organism process, catalytic activity and localization. Due to the abusive use of antibiotics, bacterial resistance has become a global problem and poses severe threats to aquaculture. The drug-resistant diseases caused by Vibrio alginolyticus have caused significant economic losses to cultured marine fish. Fructus schisandrae is used to treat inflammatory diseases in China and Japan. There have been no reports of bacterial molecular mechanisms associated with F. schisandrae stress. In this study, the inhibiting effect of F. schisandrae on the growth of V. alginolyticus was detected to understand response mechanisms at the molecular level. The antibacterial tests were analyzed via next-generation deep sequencing technology (RNA sequencing, RNA-seq). Wild V. alginolyticus (CK) was compared with V. alginolyticus, F. schisandrae incubated for 2 h, and V. alginolyticus, F. schisandrae incubated for 4 h. Our results revealed that there were 582 genes (236 upregulated and 346 downregulated) and 1068 genes (376 upregulated and 692 downregulated), respectively. Differentially expressed genes (DEGs) were involved in the following functional categories: metabolic process, single-organism process, catalytic activity, cellular process, binding, membrane, cell part, cell, and localization. FS_2 h was compared with FS_4 h, and 21 genes (14 upregulated and 7 downregulated) were obtained. The RNA-seq results were validated by detecting the expression levels of 13 genes using quantitative real-time polymerase chain reaction (qRT-PCR). The qRT-PCR results matched those of the sequencing, which reinforced the reliability of the RNA-seq. The results revealed the transcriptional response of V. alginolyticus to F. schisandrae , which will provide new ideas for studying V. alginolyticus' complex virulence molecular mechanism and the possibility of developing Schisandra to prevent and treat drug-resistant diseases. [ABSTRACT FROM AUTHOR]

• A significant decrease in gene expression of adhesion-deficient V. harveyi. • fliA , fliR , and flrB were responsible for flagellation and silenced via RNAi. • fliA , fliR , and flrB have important roles in the adhesion of V. harveyi. • fliA , fliR , flrB regulate bacterial adhesion by affecting its motility, biofilm formation. • fliA , fliR , flrB regulate adhesion ability of V. harveyi in different environments. Bacteria adhesion to fish mucus is a crucial virulence mechanism. As the initial step of bacterial infection, adhesion is impacted by bacterial motility and environmental conditions. However, its molecular mechanism is yet unclear. In this study, a significant decrease in gene expression of adhesion-deficient Vibrio harveyi was observed when the bacteria were subjected by Cu2+(50 mg/L), Pb2+(100 mg/L), Hg2+(25 mg/L), and Zn2+(50 mg/L). The genes fliA , fliR , and flrB were responsible for flagellation; being crucial for adhesion, these genes were identified and silenced via RNAi. After silencing of these genes by RNAi technology, the ability of adhesion, biofilm formation, motility, and flagella synthesis of V. harveyi were considerably reduced. Compared with the control group, it was observed that the expression levels of fliS , fliD , flgH , and flrC were significant down-regulated in fliR -RNAi, flrB -RNAi, and fliA -RNAi. This data indicates that the expression levels of most virulence genes are affected by fliA , fliR , and flrB. Also, the expression of fliA , fliR , and flrB can be influenced by the salinity, temperature, and pH. The results show that: (1) fliA , fliR , and flrB have important roles in the adhesion of V. harveyi ; (2) fliA , fliR , and flrB can regulate bacterial adhesion by affecting its motility, and biofilm formation; (3) fliA , fliR , and flrB can regulate adhesion ability of V. harveyi in different environments. [ABSTRACT FROM AUTHOR]

• Dissolved carbon mainly migrates downward from SKF under light rainfall events. • Dissolved carbon is mainly lost from the soil surface under heavy rainstorms. • Rainfall duration and amount mainly affect the concentration of dissolved carbon fractions. • The loss of dissolved carbon components is mainly regulated by runoff volume. Soil carbon in karst critical zones is an essential part of the global carbon pool, and the migration of dissolved carbon is a vital component of the carbon cycle in such regions. The unique "dual hydrological structure" makes the path and process of migration of soil dissolved carbon driven by rainfall unclear in karst slopes, which ultimately hinders the accurate evaluation of the carbon sink effect in such regions. Therefore, based on field monitoring of natural rainfall, this study evaluated the process and characteristics of the spatial migration of soil dissolved carbon in bare karst slopes and its response to natural rainfall (rainfall duration and amount). The results showed that the concentration of dissolved carbon transported in surface runoff was significantly lower than that transported within the soil layer; however, carbon loss displayed the opposite trend. Rainfall factors (rainfall amount and duration) and runoff volume significantly affected soil dissolved carbon, contributing 46.91% to soil dissolved carbon. Rainfall factors significantly affect soil dissolved carbon migration by influencing runoff. In addition, the hydrological path is an important factor affecting soil dissolved carbon transport. Our study shows that the soil and bedrock interface (SBI) and shallow karst fissures (SKF) are the main routes of dissolved carbon migration in soils in bare karst slopes. Dissolved carbon migrating along SKF is a vital contributor to the "missing carbon sink" in karst regions, and dissolved carbon migrating along the SBI is potentially an important contributor to the "missing carbon sink." This study provides primary data and is expected to serve as a reference for revealing the mechanism of karst carbon migration and transformation and accurately evaluating the carbon sink effect in karst areas. [ABSTRACT FROM AUTHOR]

The success of the pathogenic bacteria is partly attributable to their ability to thwart host innate immune responses, which includes resisting the antimicrobial functions of macrophages. And reactive oxygen species (ROS) is one of the most effective antimicrobial components of macrophages to kill invading bacteria. Our previous studies found that Aeromonas hydrophila can survive in fish macrophages, which suggested that this bacterium might take fish macrophages as their shelters to resist drug killings and other immune damage. But how A . hydrophila survive in host macrophages remains unknown. Since KatG has been reported to have not only catalase activity but also peroxidase and peroxynitritase activity, the amino acid sequence and protein structure of KatG was analyzed in this study, the function of KatG in A . hydrophila survival in and escape from host macrophages was also carried out. The bioinformatics analysis displayed that KatG of A . hydrophila B11 showed >93% homologous to that of KatG in other Aeromonas . KatG of A . hydrophila was stable silenced by shRNA and RT-qPCR confirmed the expression of KatG in KatG -RNAi was significantly reduced. The survival rate of intracellular KatG -RNAi decreased by 80% compared to that of the wild type strain B11, while the intracellular ROS level of the macrophages that phagocytosed KatG -RNAi increased 65.9% when compared to that of the macrophages phagocytosed wild-type strain. The immune escape rate of A . hydrophila decreased by 85% when the expression of KatG was inhibited. These results indicated that (1) The amino acid sequence and protein structure of KatG of A . hydrophila is conserved; (2) KatG helped A . hydrophila to survive in fish macrophages by eliminating the harm of intracellular H 2 O 2 and inhibiting intracellular ROS levels increased; (3) A small portion of intracellular A . hydrophila could escape from host macrophages for further infection, in this process KatG also played important role. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and theoretical investigation on two-phase flow boiling heat transfer with carbon dioxide (CO 2 or R744) as the refrigerant in horizontal small diameter tube at low temperature. The experimental data were obtained in the following condition, the heat flux is 7.5–30 kW/m 2 ; the mass flow rate is 300–600 kg/m 2 s; the saturation temperature is 233–273 K; the test section is made of stainless steel tubes whose inner diameters are 0.6 and 1.5 mm. The experimental results show that heat transfer coefficient increases with the increase of mass flow rate, but decreases with the increase of tubes’ inner diameter and saturation temperature, the boiling heat transfer of CO 2 has a greater effect on nucleate boiling and highly depends on heat flux. The comparative study indicates that: during the existed flow boiling heat transfer model, the model which has the best prediction accuracy presented with 79.8% of predicted points within ±30% and 21.8% mean deviation before the dryout phenomenon happened, while it was only 18.4% and 59.9% after the dryout phenomenon happened. [ABSTRACT FROM AUTHOR]