Research on the effects of processing Heishunpian from Aconiti lateralis radix praeparata on components and efficacy using the "step knockout" strategy.

Heishunpian is obtained through complex processing of Aconiti lateralis radix praeparata. However, the impact of each processing step on chemical compositions and pharmacological activities is still unclear. The mechanism of the processing needs to be further studied. The samples were all prepared using the "step knockout" strategy for UPLC-QTOF-MS analysis, and analgesic and anti-inflammatory efficacy evaluation. Each sample was analyzed by UPLC-QTOF-MS to determine the component differences. The hot plate test and acetic acid writhing test were used to evaluate the analgesic effect. Anti-inflammatory efficacy was evaluated by xylene-induced ear edema test. The correlation between components and efficacies was studied to screen the effective components for further investigating the processing of Heishunpian. Mass spectrum analysis results showed that 49 components were identified, and it appeared that brine immersion and rinsing had a great influence on the components. In the hot plate test, ibuprofen and Heishunpian had the most significant effect, while ibuprofen and the sample without rinsing showed the best efficacy for the acetic acid writhing test. The sample without dyeing had the best effect on ear edema. The correlation analysis indicated that mesaconine, aconine, 3-deoxyaconine, delbruine, and asperglaucide were potentially considered effective analgesic components. It is not recommended to remove brine immersion and rinsing. Boiling and steaming are necessary processes that improve efficacy. Dyeing, which does not have a significant impact on components and efficacy, may be an unnecessary process. This research has been of great significance in identifying anti-inflammatory and analgesic components and optimizing processing for Heishunpian.

Bioassay and Whole-Genome Analysis of Bacillus velezensis FIO1408, a Biocontrol Agent Against Pathogenic Bacteria in Aquaculture.

Bacterial disease is one of the most critical problems in aquaculture. Probiotics represent a promising biological approach to control bacterial disease because it is effective against pathogens and environmentally friendly. This study assessed the antagonistic activities of a bacterial strain FIO1408 isolated from deep-sea water against many pathogenic bacteria in aquaculture, including Listonella anguillarum, Vibrio parahaemolyticus, Vibrio alginolyticus, Aeromonas hydrophila, Edwardsiella anguillarum, Edwardsiella tarda, and Edwardsiella piscicida. The complete genome of strain FIO1408 consisted of a circular chromosome of 4,137,639 bp and two plasmids of 16,439 bp and 24,472 bp. Phylogenetic analysis showed strain FIO1408 clustered with Bacillus velezensis strains. 12 genes/gene clusters responsible for the synthesis of secondary metabolites were identified in the FIO1408 genome, including three lipopeptides, three polyketides, three bacteriocins, one siderophore, one dipeptide, and one unknown type. Also identified were 273 unique orthologous genes primarily involved in phage resistance, protein hydrolysis, environmental survivability, and genetic stability compared to B. velezensis KACC 13105, B. velezensis FZB42T, and B. velezensis NRRL B-41580. The principal safety of FIO1408 was demonstrated by genetic analyses and feeding trials. These findings will contribute to studies on the biocontrol mechanisms of B. velezensis FIO1408 and facilitate its application as a potent biological control agent against bacterial pathogens in aquaculture.

A strain of Vibrio alginolyticus isolated from Azumapecten farreri and its pathogenic mechanism using CRISPR-Cas9 technology.

Scallops have become an important aquaculture species in China because they contain high-quality protein, and scallops are important health food that combines multiple effects and high economic benefits. However, scallop aquaculture is perennially threatened by various pathogenic Vibrio species, leading to great economic losses. We obtained a strain of pathogenic bacteria, identified as Vibrio alginolyticus, from the diseased Azumapecten farreri in the scallop farming area of Huangdao District in 2018, and V. alginolyticus is one of the major shellfish pathogens. We showed that V. alginolyticus was isolated and identified as a pathogen in A. farreri for the first time. In this study, we evaluated its morphology and performed a phylogenetic analysis based on 16S rRNA gene sequencing. In addition, we performed a preliminary analysis of its pathogenic mechanisms. The Hfq protein in V. alginolyticus is an important RNA-binding protein in the quorum-sensing system that not only affects the sensitivity of Vibrio to environmental stress but also regulates a variety of functions, such as cell membrane formation, motility, and virulence towards the host. However, its effect on the pathogenesis of V. alginolyticus to A. farreri is unclear. To further investigate the pathogenic mechanism of the Hfq protein in V. alginolyticus to A. farreri, we used the CRISPR-Cas9 system to target and deplete the hfq gene fragment in V. alginolyticus and obtained the mutant strain V. ΔHfq-. We found that the peripheral flagellum of the mutant strain was lost, which reduced the motility of V. alginolyticus. Therefore, the deletion of target genes by the CRISPR/Cas9 genome editing system confirmed that the Hfq protein played a key role in reducing the ability of V. alginolyticus to infect A. farreri. In conclusion, our current findings provided valuable insights into the healthy culture of scallops.

[Rapid identification and differential markers of Curcumae Radix decoction pieces of different sources based on Heracles Neo ultra-fast gas phase electronic nose].

Since Curcumae Radix decoction pieces have multiple sources, it is difficult to distinguish depending on traditional cha-racters, and the mixed use of multi-source Curcumae Radix will affect its clinical efficacy. Heracles Neo ultra-fast gas phase electronic nose was used in this study to quickly identify and analyze the odor components of 40 batches of Curcumae Radix samples from Sichuan, Zhejiang, and Guangxi. Based on the odor fingerprints established for Curcumae Radix decoction pieces of multiple sources, the odor components was identified and analyzed, and the chromatographic peaks were processed and analyzed to establish a rapid identification method. Principal component analysis(PCA), discriminant factor analysis(DFA), and soft independent modeling cluster analysis(SIMCA) were constructed for verification. At the same time, one-way analysis of variance(ANOVA) combined with variable importance in projection(VIP) was employed to screen out the odor components with P<0.05 and VIP>1, and 13 odor components such as ß-caryophyllene and limonene were hypothesized as the odor differential markers of Curcumae Radix decoction pieces of diffe-rent sources. The results showed that Heracles Neo ultra-fast gas phase electronic nose can well analyze the odor characteristics and rapidly and accurately discriminate Curcumae Radix decoction pieces of different sources. It can be applied to the quality control(e.g., online detection) in the production of Curcumae Radix decoction pieces. This study provides a new method and idea for the rapid identification and quality control of Curcumae Radix decoction pieces.

Genomic insight of sulfate reducing bacterial genus Desulfofaba reveals their metabolic versatility in biogeochemical cycling.

BACKGROUND: Sulfate-reducing bacteria (SRB) drive the ocean sulfur and carbon cycling. They constitute a diverse phylogenetic and physiological group and are widely distributed in anoxic marine environments. From a physiological viewpoint, SRB's can be categorized as complete or incomplete oxidizers, meaning that they either oxidize their carbon substrate completely to CO2 or to a stoichiometric mix of CO2 and acetate. Members of Desulfofabaceae family are incomplete oxidizers, and within that family, Desulfofaba is the only genus with three isolates that are classified into three species. Previous physiological experiments revealed their capability of respiring oxygen. RESULTS: Here, we sequenced the genomes of three isolates in Desulfofaba genus and reported on a genomic comparison of the three species to reveal their metabolic potentials. Based on their genomic contents, they all could oxidize propionate to acetate and CO2. We confirmed their phylogenetic position as incomplete oxidizers based on dissimilatory sulfate reductase (DsrAB) phylogeny. We found the complete pathway for dissimilatory sulfate reduction, but also different key genes for nitrogen cycling, including nitrogen fixation, assimilatory nitrate/nitrite reduction, and hydroxylamine reduction to nitrous oxide. Their genomes also contain genes that allow them to cope with oxygen and oxidative stress. They have genes that encode for diverse central metabolisms for utilizing different substrates with the potential for more strains to be isolated in the future, yet their distribution is limited. CONCLUSIONS: Results based on marker gene search and curated metagenome assembled genomes search suggest a limited environmental distribution of this genus. Our results reveal a large metabolic versatility within the Desulfofaba genus which establishes their importance in biogeochemical cycling of carbon in their respective habitats, as well as in the support of the entire microbial community through releasing easily degraded organic matters.

Contrasting archaeal and bacterial community assembly processes and the importance of rare taxa along a depth gradient in shallow coastal sediments.

Marine microbial communities assemble along a sediment depth gradient and are responsible for processing organic matter. Composition of the microbial community along the depth is affected by various biotic and abiotic factors, e.g., the change of redox gradient, the availability of organic matter, and the interactions of different taxa. The community structure is also subjected to some random changes caused by stochastic processes of birth, death, immigration and emigration. However, the high-resolution shifts of microbial community and mechanisms of the vertical assembly processes in marine sediments remain poorly described. Archaeal and bacterial communities were analyzed based on 16S rRNA gene amplicon sequencing and metagenomes in the Bohai Sea sediment samples. The archaeal community was dominated by Thaumarchaeota with increased alpha diversity along depth. Proteobacteria was the dominant bacterial group with decreased alpha diversity as depth increased. Sampling sites and depths collectively affected the beta-diversity for both archaeal and bacterial communities. The dominant mechanism determining archaeal community assembly was determinism, which was mostly contributed by homogeneous selection, i.e., consistent selection pressures in different locations or depths. In contrast, bacterial community assembly was dominated by stochasticity. Co-occurrence networks among different taxa and key functional genes revealed a tight community with low modularity in the bottom sediment, and disproportionately more interactions among low abundant ASVs. This suggests a significant contribution to community stabilization by rare taxa, and suggests that the bottom layer, rather than surface sediments may represent a hotspot for benthic microbial interactions.

Inhibition of the IRE1/JNK pathway in renal tubular epithelial cells attenuates ferroptosis in acute kidney injury.

Backgroud: Ferroptosis is a form of regulated cell death in ischemia-reperfusion (I/R) injury models. Acute kidney injury (AKI) induced by I/R injury can result in cell death, and subcellular structural changes, including expansion of the endoplasmic reticulum (ER), mitochondrial shrinkage, and other morphological changes. Inositol requiring enzyme 1 (IRE1) a proximal ER stress sensor, activates c-Jun NH2-terminal kinases (JNK) in response to ER stress, which is inextricably linked to ER. Method: To determine the resulting damage and relationship between ferroptosis and the IRE1/JNK pathway in AKI, we modeled AKI in I/R renal injury mice and hypoxia/reoxygenation (H/R) HK-2 cells, as in vivo and in vitro experiments, respectively. Results: In I/R renal injury mice, we found that abnormal renal function; damage of renal tubular epithelial cells; activation of the IRE1/JNK pathway and ferroptosis. Our in vitro study showed a large number of reactive oxygen species and more ferroptotic mitochondria in H/R HK-2 cells. By inhibiting IRE1/JNK in I/R renal injury mice, we observed decreased blood urea nitrogen, creatinine, and tissue injury, compared with the I/R group, we also found the markers of ferroptosis changed, including decreased 4-hydroxynonenal and increased glutathione peroxidase 4, as well as in H/R induced IRE1/JNK knock-down HK-2 cell lines (stable depletion). Furthermore, inhibition of ferroptosis could also attenuate the IRE1/JNK pathway in mice following I/R and HK-2 cells following H/R. Conclusion: We observed cross-talk between the IRE1/JNK pathway and ferroptosis in I/R or H/R induced AKI. Our findings suggest that ferroptosis plays an important role in I/R induced AKI, and that inhibition of the IRE1/JNK pathway can protect against I/R induced renal injury by inhibiting ferroptosis. The inhibition of the IRE1/JNK pathway could therefore be a feasible therapeutic target for treatment of AKI.

The IRE1/JNK signaling pathway regulates inflammation cytokines and production of glomerular extracellular matrix in the acute kidney injury to chronic kidney disease transition.

BACKGROUND: The transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is extremely complex. Incomplete renal tubule repair, inflammation, and endoplasmic reticulum (ER) stress all play major roles. AKI activates ER stress, and the sensor protein inositol-requiring kinase-1 (IRE1) mediates inflammation by promoting the phosphorylation of C-jun NH2-terminal kinase (JNK). The interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway is associated with the secretion of renal extracellular matrix (ECM) and fibrosis. It remains unclear whether these signaling pathways play a role in the AKI-CKD transition. METHODS: In this study, a mouse model of ischemia-reperfusion (I/R) with bilateral renal artery clipping was used. IRE1 or JNK inhibitors were also injected to confirm their roles in the AKI-CKD transition. The renal function of the mice was determined by observing the pathology of the renal tubules and glomeruli through electron microscopy, immunohistochemistry, western blotting and quantitative real-time PCR. RESULTS: I/R stimulates ER stress and the IRE1/JNK pathway in the renal tubules in a short period of time, leading to continuous inflammation. Long-term I/R injury activates the STAT3 pathway in the glomeruli, activates mesangial cells proliferation, causes secretion of large amounts of glomerular ECM, and promotes glomerular sclerosis. This damage to the renal tubules and glomeruli is significantly reduced in I/R model mice pretreated with IRE1 or JNK inhibitors. CONCLUSION: These findings suggested that the IRE1/JNK pathway regulates the inflammatory cytokines caused by AKI and continues to activate the STAT3 pathway and production of ECM in the glomeruli at late stages, suggesting the feasibility of targeted therapy for the AKI-CKD transition.

[Quality value transmitting of substance benchmarks of Zhuru Decoction].

A total of 18 batches of Zhuru Decoction samples were prepared. Chromatographic fingerprints were established for Zhuru Decoction and single decoction pieces, the content of which was then determined. The extraction rate ranges, content, and transfer rate ranges of puerarin, liquiritin, and glycyrrhizic acid, together with the common peaks and the similarity range of the fingerprints, were determined to clarify key quality attributes of Zhuru Decoction. The 18 batches of Zhuru Decoction samples had 25 common peaks and the fingerprint similarity higher than 0.95. Puerariae Lobatae Radix, Glycyrrhizae Radix et Rhizoma, and Zingiberis Rhizoma Recens had 21, 3, and 1 characteristic peaks, respectively. The 18 batches of samples showed the extraction rates within the range of 18.45%-25.29%. Puerarin had the content of 2.20%-3.07% and the transfer rate of 38.5%-45.9%; liquiritin had the content of 0.24%-0.85% and the transfer rate of 15.9%-37.5%; glycyrrhizic acid had the content of 0.39%-1.87% and the transfer rate of 16.2%-32.8%. In this paper, the quality value transmitting of substance benchmarks of Zhuru Decoction was analyzed based on chromatographic fingerprints, extraction rate, and the content of index components. A scientific and stable method was preliminarily established, which provided a scientific basis for the quality control and formulation development of Zhuru Decoction.

Single-cell Raman-activated sorting and cultivation (scRACS-Culture) for assessing and mining in situ phosphate-solubilizing microbes from nature.

Due to the challenges in detecting in situ activity and cultivating the not-yet-cultured, functional assessment and mining of living microbes from nature has typically followed a 'culture-first' paradigm. Here, employing phosphate-solubilizing microbes (PSM) as model, we introduce a 'screen-first' strategy that is underpinned by a precisely one-cell-resolution, complete workflow of single-cell Raman-activated Sorting and Cultivation (scRACS-Culture). Directly from domestic sewage, individual cells were screened for in-situ organic-phosphate-solubilizing activity via D2O intake rate, sorted by the function via Raman-activated Gravity-driven Encapsulation (RAGE), and then cultivated from precisely one cell. By scRACS-Culture, pure cultures of strong organic PSM including Comamonas spp., Acinetobacter spp., Enterobacter spp. and Citrobacter spp., were derived, whose phosphate-solubilizing activities in situ are 90-200% higher than in pure culture, underscoring the importance of 'screen-first' strategy. Moreover, employing scRACS-Seq for post-RACS cells that remain uncultured, we discovered a previously unknown, low-abundance, strong organic-PSM of Cutibacterium spp. that employs secretary metallophosphoesterase (MPP), cell-wall-anchored 5'-nucleotidase (encoded by ushA) and periplasmic-membrane located PstSCAB-PhoU transporter system for efficient solubilization and scavenging of extracellular phosphate in sewage. Therefore, scRACS-Culture and scRACS-Seq provide an in situ function-based, 'screen-first' approach for assessing and mining microbes directly from the environment.

Physicochemical parameters combined flash GC e-nose and artificial neural network for quality and volatile characterization of vinegar with different brewing techniques.

Vinegar is a kind of traditional fermented food, there are significant variances in quality and flavor due to differences in raw ingredients and processes. The quality assessment and flavor characteristics of 69 vinegar samples with 5 brewing processes were analyzed by physicochemical parameters combined with flash gas chromatography (GC) e-nose. The evaluation system of quality and the detection method of flavor profile were established. 17 volatile flavor compounds and potential flavor differential compounds of each brewing process were identified. The artificial neural network (ANN) analysis model was established based on the physicochemical parameters and the analysis of flash GC e-nose. Although the physicochemical parameters were more intuitive in quality evaluating, the flash GC e-nose could better reflect the flavor characteristics of vinegar samples and had better fitting, prediction and discrimination ability, the correct rates of training and prediction of flash GC e-nose trained ANN model were 98.6% and 96.7%, respectively.

Disproportionate responses between free-living and particle-attached bacteria during the transition to oxygen-deficient zones in the Bohai Seawater.

The Bohai Sea has recently suffered several seasonal oxygen-deficiency, even hypoxia events during the summer. To better understand effects of dissolved oxygen (DO) concentration on the bacterial composition in particle attached (PA) and free living (FL) fractions during the transition from oxic water to low oxygen conditions, the bacterial communities under three different oxygen levels, i.e., high oxygen (HO, close to 100% O2 saturation), medium oxygen (MO, close to 75% O2 saturation), and low oxygen (LO, close to 50% O2 saturation) in the Bohai Sea were investigated using 16S rRNA amplicon sequencing. Fourteen water samples from 5 stations were collected during a cruise from August to September in 2018. The results showed that the sequences of Proteobacteria and Actinobacteriota jointly accounted for up to 74% across all 14 samples. The Shannon index in HO samples were significantly higher than in LO samples (P < 0.05), especially in PA communities. The composition of bacterial communities varied by oxygen concentration in all samples, and the effect was more pronounced in the PA fraction, which indicates that the PA fraction was more sensitive to the change in oxygen concentration, possibly due to the tighter interactions in this community than in the FL fraction. This study provides novel insights into the distribution of bacterial communities, and clues for understanding the responses of bacterial communities in the Bohai Sea during the transition from the oxic to oxygen-deficient zones.

Kushneria phosphatilytica sp. nov., a phosphate-solubilizing bacterium isolated from a solar saltern.

A Gram-stain-negative, motile, rod-shaped, non-endospore-forming, aerobic and halophilic bacterium, designated strain YCWA18T, was isolated from the sediment of Jimo-Daqiao saltern in China. This strain was able to grow at NaCl concentrations in the range 0.5-20 % (w/v) with optimum growth at 6 % (w/v) NaCl. Growth occurred at temperatures of 4-40 °C (optimum 28 °C) and pH 4.0-9.0 (optimum 7.0). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YCWA18T belonged to the genus Kushneria and shared the highest sequence similarity of 98.7 % with Kushneria sinocarnis DSM 23229T. Moreover, the phylogenetic analysis based on the 23S rRNA gene sequence also confirmed the phylogenetic position of this novel strain. The predominant fatty acids were C16 : 0, C17 : 0 cyclo and C12 : 0 3-OH. The major isoprenoid quinone was Q-9 (94.2 %) and the polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), an unidentified aminolipid (AL), an unidentified phospholipids (PL) and two unidentified lipids (L). The complete genome of strain YCWA18T consisted of a single, circular chromosome of 3 624 619 bp, with an average G+C content of 59.1 mol%. A genome-based phylogenetic tree constructed using an up-to-date bacterial core gene set (UBCG) showed that strain YCWA18T formed a clade with K. sinocarnis DSM 23229T. However, the level of the ANI and dDDH values between strain YCWA18T and K. sinocarnis DSM 23229T were 82.3 and 24.6 %, respectively, which were low enough to distinguish strain YCWA18T from K. sinocarnis DSM 23229T. Overall, based on the phenotypic, chemotaxonomic, phylogenetic and genomic analyses, strain YCWA18T represents a novel species of genus Kushneria. The name Kushneria phosphatilytica sp. nov. is proposed, with the type strain YCWA18T (=CGMCC 1.9149T=NCCB 100306T).

Comparative genomics of the sequential Pseudomonas aeruginosa isolates obtained from the continuous imipenem stress evolution.

Pseudomonas aeruginosa is a major opportunistic human pathogen that causes nosocomial infections, and the proportion of carbapenem resistance has recently dramatically increased in P. aeruginosa due to the overuse of them. In this study, strains G10 and G20, with minimum inhibitory concentration (MIC) of imipenem of 16 µg/ml and more than 32 µg/ml, were isolated during continuous subculture of cells exposed to stepwise increasing concentrations of imipenem, respectively. The genomes of G10 and G20 were sequenced and compared with parental strain (P. aeruginosa ATCC 27853, G0). There were 59, 59, and 58 genes involved in antibiotic resistance which were predicted in G0, G10, and G20, respectively, while 374, 366, and 363 genes involved in virulence factors were identified among these three strains. Due to the significantly different MICs of imipenem and highly similar profiles of antibiotic resistance and virulence factors related genes among three strains, the specific genetic variations that occurred were identified and compared, including single nucleotide polymorphisms (SNPs), insertions and deletions (InDels), and structural variations (SVs). The increase in the MIC of imipenem was proposed to be linked to mutations involved in polyamine biosynthesis, biofilm formation, OprD, and efflux pump functions. This study aims to clarify the underlying mechanism of imipenem resistance and provide alternative strategies for reducing resistance in P. aeruginosa. KEY POINTS: • Strains with different imipenem MIC were obtained via laboratory selection evolution. • Whole genomes of two strains with different MIC of imipenem were sequenced. • Underlying mechanism of imipenem resistance was clarified via comparative genomics.

Inhibition of IRE1/JNK pathway in HK-2 cells subjected to hypoxia-reoxygenation attenuates mesangial cells-derived extracellular matrix production.

Endoplasmic reticulum (ER) stress and inflammatory responses play active roles in the transition of acute kidney injury (AKI) to chronic kidney disease (CKD). Inositol-requiring enzyme 1 (IRE1) activates c-Jun NH2 -terminal kinase (JNK) in ER stress. Tubular epithelial cells (TEC) are the main injury target and source of AKI inflammatory mediators. TEC injury may lead to glomerulosclerosis, however, the underlying mechanism remains unclear. Here, hypoxia/reoxygenation (H/R) HK-2 cells were used as an AKI model. To determine the partial effects of TEC injury on the glomerulus, HK-2 cells after H/R were co-cultured with human renal mesangial cells (HRMC). H/R up-regulated ER stress, IRE1/JNK pathway, IL-6 and MCP-1 in HK-2 cells. Stimulation of HRMC with IL-6 enhanced their proliferation and the expression of glomerulosclerosis-associated fibronectin and collagen IV via signal transducer and activator of transcription 3 (STAT3) activation. Similar responses were observed in HRMC co-cultured with HK-2 cells after H/R. IRE1/JNK inhibition reversed these injury responses in HRMC. IRE1/JNK stable knock-down in HK-2 cells and shRNA-mediated STAT3 depletion in HRMC confirmed their role in inflammation/glomerulosclerosis. These findings suggest that IRE1/JNK pathway mediates inflammation in TEC, affecting mesangial cells. The inhibition of this pathway could be a feasible approach to prevent AKI-CKD transition.

Nearest vent, dearest friend: biodiversity of Tiancheng vent field reveals cross-ridge similarities in the Indian Ocean.

Biodiversity of hydrothermal vents in the Indian Ocean, particularly those on the Southwest Indian Ridge (SWIR), are still relatively poorly understood. The Tiancheng field on the SWIR was initially reported with only a low-temperature diffuse flow venting area, but here we report two new active areas, including a chimney emitting high-temperature vent fluids. Biological sampling in these new sites doubled the known megafauna and macrofauna richness reported from Tiancheng. Significantly, we found several iconic species, such as the scaly-foot snail and the first Alviniconcha population on the SWIR. Tiancheng shares a high proportion of taxa with vents on the Central Indian Ridge (CIR) and lacks a number of key taxa that characterize other vents investigated so far on the SWIR. Population genetics of the scaly-foot snail confirmed this, as the Tiancheng population was clustered with populations from the CIR, showing low connectivity with the Longqi field. Unlike the previously examined populations, scales of the Tiancheng scaly-foot snail were coated in zinc sulfide, although this results only from precipitation. The close connection between Tiancheng and CIR vents indicates that the dispersal barrier for vent endemic species is not the Rodriguez Triple Junction as previously suggested but the transformation faults between Tiancheng and Longqi, warranting further studies on deep currents in this area to resolve the key barrier, which has important implications for biological conservation.

Influences of Seasonal Monsoons on the Taxonomic Composition and Diversity of Bacterial Community in the Eastern Tropical Indian Ocean.

The Indian Ocean is characterized by its complex physical systems and strong seasonal monsoons. To better understand effects of seasonal monsoon-driven circulation on the bacterioplanktonic community structure in surface waters and the bacterial distribution response to vertical stratification, patterns of seasonal, and vertical distribution of bacterial communities in the Eastern Tropical Indian Ocean were investigated using 16S rRNA gene profiling. Water samples were collected during the Southwest monsoon (from June to August), the fall inter-monsoon (from October and November) and the Northeast monsoon (from December to January), respectively, onboard during three cruises from July 2016 to January 2018. Surface bacterioplankton communities in these three seasons and in the upper water (3-300 m with six depths) during the Northeast monsoon contained a diverse group of taxa, mainly Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, and Chloroflexi. Redundancy discriminant analysis (RDA) uncovered that temperature, salinity, and dissolved oxygen (DO) were crucial environmental parameters that affected the structure of bacterial community in overall surface samples. However, significant differences in the composition of the bacterial community are likely due to changes in concentrations of salinity during the fall inter-monsoon, while phosphate for both the Southwest monsoon and the Northeast monsoon. Pearson's analysis revealed that the seasonal variation rather than the vertical variation of environmental factors had a more significant impact on the composition of bacterial community. In addition, a clear seasonal pattern of bacterial co-occurrence showed that inter-taxa associations during the fall inter-monsoon were closer than during the Northeast monsoon and the Southwest monsoon. Overall, our results implied clear differences in the composition of bacterial community, with more pronounced seasonal variation compared to the vertical variation in response to environmental changes.

Marine microplastic-associated bacterial community succession in response to geography, exposure time, and plastic type in China's coastal seawaters.

Microplastics have emerged as new pollutants in oceans. Nevertheless, information of the long-term variations in the composition of plastic-associated microbial communities in coastal waters remains limited. This study applied high-throughput sequencing to investigate the successional stages of microbial communities attached to polypropylene and polyvinyl chloride microplastics exposed for one year in the coastal seawater of China. The composition of plastisphere microbial communities varied remarkably across geographical locations and exposure times. The dominant bacteria in the plastisphere were affiliated with the Alphaproteobacteria class, particularly Rhodobacteraceae, followed by the Gammaproteobacteria class. Scanning electron microscopy analysis revealed that the microplastics showed signs of degradation. Microbial communities showed adaptations to plastisphere including more diverse microbial community and greater "xenobiotics biodegradation and metabolism" in metabolic pathway analysis. The findings elucidate the long-term changes in the community composition of microorganisms that colonize microplastics and expand the understanding of plastisphere microbial communities present in the marine environment.