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Simple Summary: Grass carp reovirus genotype Ⅱ (GCRV Ⅱ) is the leading cause of death in grass carp. To investigate the involved molecular responses against the GCRV Ⅱ infection, we performed comparative transcriptomic analysis in the spleen and liver of rare minnow injected with virulent and attenuated strains. Results showed that the virulent strain infection especially induced tissue-specific alteration and caused severe suppression of hemorrhage related pathways in spleen. Our finding provides new insights on the interactions between host and GCRV Ⅱ. Grass carp reovirus genotype Ⅱ (GCRV Ⅱ) causes a variety of fish hemorrhagic disease, which seriously affects the sustainable development of grass carp aquaculture in China. Rare minnow (Gobiocypris rarus) is an ideal model fish to study the pathogenesis of GCRV Ⅱ. To investigate the involved molecular responses against the GCRV Ⅱ infection, we performed comparative transcriptomic analysis in the spleen and liver of rare minnow injected with virulent strain DY197 and attenuated strain QJ205. Results showed that the virulent DY197 strain induced more differently expressed genes (DEGs) than the attenuated QJ205 strain, and tissue-specific responses were induced. In the spleen, the attenuated and virulent strains induced different DEGs; the attenuated QJ205 infection activated steroid synthesis pathway that involved in membrane formation; however, virulent DY197 infection activated innate immunity and apoptosis related pathways while suppressing cell proliferation and migration related pathways that are important for damage tissue repair, as well as hemorrhage related pathways. In the liver, the attenuated and virulent strains infection induced similar DEGs; both strains infection activated immunity and apoptosis related pathways but suppressed metabolism-related pathways; virulent DY197 infection especially activated protein digestion and absorption-related pathways and suppressed steroid synthesis pathway. To conclude, virulent strain infection especially induced tissue-specific alterations and caused severe suppression of hemorrhage-related pathways in spleen. Our findings will contribute to better understanding of the interactions between host and GCRV II. [ABSTRACT FROM AUTHOR]

Background: Riverine ecosystems are one of the most important reservoirs of antibiotic resistance genes (ARGs) in the environment, but the occurrence and controlling factors of ARG distribution in different habitats of riverine ecosystems remain poorly understood. In this study, a metagenomic approach was used to characterize ARG types and their abundance in different habitats (rhizosphere soil, surface bulk soil, bottom bulk soil, and sediment) of riverine ecosystems in eastern China. Sampling sites were located along different rivers of eastern China, which are geographically isolated. Differences in bacterial communities, mobile genetic elements (MGEs), pattern and intensity of human activities, climate, and other environmental factors at the sampling sites and habitats were expected to affect ARG occurrence. Results: ARGs were observed with high variations in diversity (44–206 subtypes) and abundance (6.85–105.68 ×/Gb). There were significant south-north differences in ARG occurrence in the same habitat, except for surface bulk soil. And the significant difference was found in ARGs among four southern habitats. South–north differences in ARGs of the same habitat were mainly attributed to the combination of different occurrence frequencies and habitat selections of ARGs. Differences in ARG profiles among the four habitats in the south and the north were both mainly attributed to the different occurrence frequencies of ARGs. Bacterial communities and MGEs (Mobile genetic elements) could account for the observed variance in the resistome of riverine ecosystems across eastern China. The co-occurrences of specific ARGs with bacterial communities and MGEs were more frequent at the northern sampling sites than in the south, and co-occurrence patterns (i.e. ARGs and bacterial communities or ARGs and MGEs) varied between the habitats. Moreover, building land in all habitats, except bulk soils, showed significant positive correlations with ARG abundance. Conclusion: This study reveals a high variance in the resistome of riverine ecosystems in eastern China and its controlling factors. We appeal to the importance of assessment of ARGs in the riverine ecosystem and the need for future prevention and intervention of ARG spread. [ABSTRACT FROM AUTHOR]

The largemouth bass (Micropterus salmoides) is one of the most economically valuable fish species in China. In this study, a bacterial pathogen was isolated from the internal organs of diseased M. salmoides, and the strain was named WH21406. This isolate was identified as Aeromonas caviae on the basis of its morphology, biochemical features and 16S rDNA phylogenetic analysis. Four virulence genes related to pathogenicity, namely, flagella (fla), elastase (ela), haemolysin (hly) and aerolysin (aer), were detected in this isolate. The median lethal dosage (LD50) of A. caviae WH21406 for M. salmoides was calculated to be 3.46 × 105 CFU mL−1. The histopathological analysis showed obvious tissue damage in the gill, liver, kidney, spleen and gut of the diseased fish. The antibiotic susceptibility test demonstrated that strain WH21406 was highly sensitive to enrofloxacin, norfloxacin, streptomycin and amikacin. The results of this study provide a foundation for the diagnosis, prevention and treatment of A. caviae infection in M. salmoides. [ABSTRACT FROM AUTHOR]

Yellow‐head catfish, Pelteobagrus fulvidraco, is an economically important specific species in aquaculture in China. However, at present disease has become a major concern of this fish. In this study, a bivalent vaccine was generated, containing two formalin‐inactivated bacteria at different mixing ratio of 3:7, 5:5 and 7:3 of A. veronii and E. ictaluri in volume with a concentration at 1.0 × 108 CFU mL−1 for each.The immunization efficacies were evaluated by measuring lysozyme activity, serum total protein, serum C3, specific antibodies, expression of immune‐related genes and survival rate against A. veroniiorE. ictaluri. The results showed that the bivalent vaccine with a mixing ratio of 3:7 of A. veroniiandE. ictaluri in volume presented the highest immunization efficacy. In this immunization group, the lysozyme activity, serum total protein and serum C3 had a noticeable increase at 7 dpi. IgM gene was significantly up‐regulated to the peak at 7 dpi in the spleen and at 14 dpi in the kidney after immunization. MR (Mannose receptor) and Ctl (C‐type lectin) genes significantly increased and reached their maximum at 24 h after immunization in both spleen and head kidney. Higher antibody levels were observed in vaccinated fish at day 21 post immunization. The challenge test showed that the relative survival percent in the immunized group with the mixing ratio of 3:7 of A. veroniiandE. ictaluri in volume was 50.61% ± 2.64 and 62.82% ± 2.22 against A. veronii and E. ictaluri infection respectively. These results indicated that the bivalent vaccine of inactivated A. veronii and E. ictaluri can effectively induce immune responses and protect yellow‐head catfish against A. veronii and E. ictaluri infection. [ABSTRACT FROM AUTHOR]

The Chinese giant salamander, belonging to an ancient amphibian lineage, is the largest amphibian existing in the world, and is also an important animal for artificial cultivation in China. However, some aspects of the innate and adaptive immune system of the Chinese giant salamander are still unknown. The Chinese giant salamander iridovirus (GSIV), a member of the Ranavirus genus (family Iridoviridae), is a prominent pathogen causing high mortality and severe economic losses in Chinese giant salamander aquaculture. As a serious threat to amphibians worldwide, the etiology of ranaviruses has been mainly studied in model organisms, such as the Ambystoma tigrinum and Xenopus. Nevertheless, the immunity to ranavirus in Chinese giant salamander is distinct from other amphibians and less known. We review the unique immune system and antiviral responses of the Chinese giant salamander, in order to establish effective management of virus disease in Chinese giant salamander artificial cultivation. [ABSTRACT FROM AUTHOR]

The capacity of riparian wetlands to remove nitrogen from upland runoff through the denitrification process is mainly controlled by soil properties and biological communities. However, the pathways or mechanisms by which soil properties and biological communities may regulate riparian denitrification rates are still largely unknown. Here, we measured the potential and unamended denitrification rates in sediments from riverine wetlands along a nitrogen‐rich river in subtropical China. We also investigated the plant richness, vegetation cover, and abundance of denitrifying microorganisms in wetland soils. The results show that both potential and unamended denitrification rates presented strong seasonality, and were found to be significantly associated with nitrogen concentration in soils, implying that denitrification process in riparian wetlands is probably nitrogen limited. Moreover, potential and unamended denitrification rates were positively related to denitrifier abundance, plant richness, and vegetation cover. Using structural equation modeling, we found that moisture and nitrogen concentration could influence denitrification rates directly; the indirect effects of these factors on denitrification rates mediated through modulating the structure of plant and microbial communities. These findings suggest that denitrification rates and nitrogen removal capacities in riparian wetlands are jointly modulated by soil properties and biological communities. [ABSTRACT FROM AUTHOR]

Phosphorus (P) enrichment as a result of anthropogenic activities can potentially alter plant C:N:P stoichiometry. However, the influence of different P enrichment frequencies on plant C:N:P stoichiometry in P-limited ecosystems is still unclear. In this study, we conducted a P-addition experiment to elucidate the effect of various P enrichment frequencies on the plant C:N:P stoichiometry of Carex brevicuspis in a freshwater wetland at Dongting Lake, China. We used four P enrichment frequencies (treatment A: no P addition; treatment B: three 0.1 g kg−1 additions at 10-day intervals; treatment C: two 0.15 g kg−1 additions at 15-day intervals; and treatment D: one 0.3 g kg−1 addition during the experimental period) in a factorial design with an experimental duration of 30 days. Biomass accumulation was lowest in the treatment A and highest in the treatment C, and increased with decreasing P addition frequency. The shoot:root ratio did not differ significantly between the four treatments. Both foliar and root C concentrations were not significantly different between the treatments. Foliar N concentration was significantly lower in the treatment D than in the other three treatments, while root N concentration did not differ significantly between the treatments. Both foliar and root P concentrations, and foliar C:N were much higher in the treatment B than in the treatment A. However, root C:N did not differ significantly between treatments. Both foliar and root C:P and N:P of C. brevicuspis were lower in the treatment B than in the treatment A. These results indicated that different frequencies of P addition significantly influenced plant growth. Moreover, P enrichment, rather than frequency, significantly influenced plant C:N:P stoichiometry. Our results improve our understanding of the influence of different P enrichment frequencies on plant C:N:P stoichiometry and nutrient cycling in freshwater wetlands. [ABSTRACT FROM AUTHOR]

Globally, shallow lakes have suffered from excessive nitrogen (N) loading due to increased human activities in catchments, resulting in water quality degradation and aquatic biodiversity loss. Sediment denitrification, which reduces nitrate (NO 3 − ) to N gaseous products, is the most important mechanism for permanent N removal in freshwater lakes. However, the relative contribution of abiotic and biotic factors to the sediment denitrification is highly variable. Here, we determined the unamended denitrification rate and nitrous oxide (N 2 O) production rate of 74 sediment samples from 22 eutrophic lakes in the Yangtze River basin. We also quantified the diversity and abundance of denitrifying communities using nirK and nirS genes. The results of variance partitioning analyses showed that water physicochemical properties (e.g., dissolved oxygen) and nutrients (e.g., NO 3 − concentration) but not denitrifier communities and submerged vegetation were the major factor groups predicting denitrification and N 2 O production rates. Path analyses further revealed that water physicochemical properties and nutrients could affect denitrification and N 2 O production rates both directly and indirectly, and the direct effects were considerably higher than the indirect effects mediated through changes in sediment characteristics, denitrifier communities and submerged vegetation. These findings suggest that the dominant N removal process in Yangtze lakes is largely regulated by abiotic factors rather than diversity and abundance of denitrifiers and submerged macrophytes. Additionally, the findings in this study are helpful in developing a targeted strategy to assess and enhance the N removal capability of eutrophic lakes in China. [ABSTRACT FROM AUTHOR]

Infectious spleen and kidney necrosis virus (ISKNV) has been recognized as the causative agent of the most serious disease in cultured mandarin fish, Siniperca chuatsi, in China. Disease outbreaks have resulted in substantial losses to the aquaculture industry. Currently, reliable laboratory detection and identification methods are available for this virus. However, rapid detection methods applicable for on-site diagnosis of this infectious agent are unavailable. To address this need, a nearly instrument-free, cost-effective and simple detection method was developed and optimized and incorporates cross priming amplification coupled with vertical flow visualization for rapid identification of ISKNV (ISKNV-CPA-VF). Results show that cross circulation amplification targeting the conserved region of the major capsid protein (MCP) regiment of the ISKNV genome had a sensitivity 10 times greater than traditional PCR at 64 °C within 60 min. The optimized concentration of dNTPs and the concentration for Mg 2+ were 1.0 mmol/L and 10 mmol/L, respectively. No cross-reactions with other viruses or bacteria were observed. When combined with the nucleic acid strip detection technology, visual detection of ISKNV amplified products was realized within 3–5 min following amplification. The simplicity and nearly instrument-free method for this ISKNV-CPA-VF assay shows great potential for on-site diagnostics of ISKNV infection in Siniperca chuatsi. [ABSTRACT FROM AUTHOR]

Freshwater lakes provided an ideal media for the accumulation and propagation of antibiotic resistance genes (ARGs), because they were susceptible to anthropogenic impacts. Land reclamation and urbanization exerted severe anthropogenic impacts on lakes from middle and lower reaches of the Yangtze River, China over the past decades. In this study, 15 lakes in the region were selected to understand the level and variability of ARGs. Proportion of different land use types was applied to display the land reclamation and urbanization around each lake. For sulfonamide resistance ( sul ) genes, sul 1 had the highest relative abundance in sediments, with maximum 2.11 × 10 −1 copies/16SrRNA copy in Gehu Lake. For tetracycline resistance ( tet ) genes, tet G had the highest average value of relative abundance (4.74 × 10 −3 copies/16SrRNA copy), followed by tet B, tet A, tet Q and tet M. Class I integron ( int I1) played an important role in acquisition and dissemination of sul 1 and tet G. Sediment characteristics (moisture, density, total nitrogen, total carbon, ammonium, and nitrate) were found to have no significant effect on ARG distribution. Taihu Lake and Yangcheng Lake which exhibited high sul and tet genes had the high proportion of built-up land use. [ABSTRACT FROM AUTHOR]

Reservoirs created by damming rivers and inundating terrestrial areas can have serious effects on ecosystem structure and functions of riverine wetlands. Here, we tested the hypothesis that reservoir shorelines had similar vegetation characteristics to adjacent riverine wetlands due to propagule dispersal and examined whether vegetation distribution in reservoir shorelines was related to topographic factors. We investigated 146, 44, and 67 plots in shorelines of the Danjiangkou Reservoir, upstream and downstream wetlands, and tributary wetlands, respectively. Results revealed that reservoir shorelines had a similarity of 45% to riverine wetlands in species composition. Two-way indicator species analysis demonstrated that communities in reservoir shorelines were dominated by mesophyte species such as Cynodon dactylon and Abutilon theophrasti, while communities in riverine wetlands were largely dominated by hygrophyte species including Paspalum paspaloides, Alternanthera philoxeroides, and Polygonum hydropiper. Moreover, species diversity and percentage of perennial species in reservoir shorelines were lower than those in riverine wetlands. Canonical correspondence analysis indicated that topographic factors including landform, slope, and distance to water were important factors regulating species and community distribution in reservoir shorelines. Landform and slope also strongly influenced the species diversity of shoreline vegetation. Results from this study may contribute to a better understanding of shoreline vegetation in large subtropical reservoirs and provide information for future re-vegetation in the Danjiangkou Reservoir after dam heightening. [ABSTRACT FROM AUTHOR]

Introduction: Lakes play an important role in socioeconomic development and ecological balance in China, but their water quality has deteriorated considerably in recent decades. In this study, we investigated the spatial-temporal variations of eutrophication parameters (secchi depth, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll- a, trophic level index, and trophic state index) and their relationships with lake morphology, watershed land use, and socioeconomic factors in the Yunnan Plateau lakes. Discussion: Results indicated that about 77.8% of lakes were eutrophic according to trophic state index. The plateau lakes showed spatial variations in water quality and could be classified into high-nutrient and low-nutrient groups. However, because watersheds were dominated by vegetation, all eutrophication parameters except chlorophyll- a showed no significant differences between the wet and dry seasons. Lake depth, water residence time, volume, and percentage of built-up land were significantly related to several eutrophication parameters. Agricultural land use and social-economic factors had no significant correlation with all eutrophication parameters. Stepwise regression analyses demonstrated that lake depth and water residence time accounted for 73.8% to 87.6% of the spatial variation of single water quality variables, respectively. Redundancy analyses indicated that lake morphology, watershed land use, and socioeconomic factors together explained 74.3% of the spatial variation in overall water quality. The results imply that water quality degradation in the plateau lakes may be mainly due to the domestic and industrial wastewaters. This study will improve our understanding of the determinants of lake water quality and help to design efficient strategies for controlling eutrophication in the plateau region. [ABSTRACT FROM AUTHOR]

Lake-water quality is highly dependent on the landscape characteristics in its respective watershed. In this study, we investigated the relationships between lake-water quality and landscape composition and configuration within the watershed in the Yangtze River basin of China. Water quality variables, including pH, electrical conductivity (EC), dissolved oxygen (DO), Secchi depth (SD), NO2−, NO3−, NH4+, TN, TP, chemical oxygen demand (CODMn), chlorophyll- a (Chl- a), and trophic state index (TSI), were collected from 16 lakes during the period of 2001-2003. Landscape composition (i.e. the percentage of vegetation, agriculture, water, urban, and bare land) and landscape configuration metrics, including number of patches (NP), patch density (PD), largest patch index (LPI), edge density (ED), mean patch area (MPA), mean shape index (MSI), contagion (CONTAG), patch cohesion index (COHESION), Shannon's diversity index (SHDI), and aggregation index (AI), were calculated for each lake's watershed. Results revealed that the percentage of agriculture was negatively related to NO2−, TN, TP, Chl- a concentrations, and TSI, while the percentage of urban was significantly correlated with EC, NH4+, and CODMn concentrations. Among landscape-level configuration metrics, only ED showed significant relationships with TN, TP concentrations, and TSI. However, at the class level, the PD, LPI, ED, and AI of agriculture and urban land uses were significantly correlated with two or more water quality variables. This study suggests that, for a given total area, large and clustered agricultural or urban patches in the watershed may have a greater impact on lake-water quality than small and scattered ones. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The Danjiangkou Reservoir, constructed in 1970s, is the water source area of the middle route of China''s interbasin South-to-North Water Transfer Project. To serve such purpose, the Danjiangkou Reservoir Dam will be increased from its present 162.0m to 176.6m, and its regular water level from 157m to 170m above mean sea level. Vegetation development in the new reservoir margins is therefore one of great environmental concerns. To explore the potential origin of species in the present reservoir margin vegetation, we investigated and quantified the composition in the soil seed banks and established vegetations of the reservoir margins and its upstream- and downstream-wetlands. In both existent vegetation and seed banks, most species and seedlings were found in upstream wetlands, followed by reservoir margins and downstream wetlands. Seedling density of downstream wetlands was reduced by 75–80% compared to upstream wetlands and reservoir margins. This suggests that presence of the dam reduced the diversity and abundance of downstream propagules. Sørensen''s coefficient and the comparisons of rare species indicated that the seed bank composition of reservoir margins was evidently associated with upstream wetlands. It implies that hydrochorous transport of seeds from the upstream catchment is critical for plant colonization of the reservoir margins. [Copyright &y& Elsevier]

The grass carp reovirus (GCRV) causes severe hemorrhagic disease with high mortality and leads to serious economic losses in the grass carp (Ctenopharyngodon idella) industry in China. Oral vaccine has been proven to be an effective method to provide protection against fish viruses. In this study, a recombinant baculovirus BmNPV-VP35-VP4 was generated to express VP35 and VP4 proteins from GCRV type Ⅱ via Bac-to-Bac baculovirus expression system. The expression of recombinant VP35-VP4 protein (rVP35-VP4) in Bombyx mori embryo cells (BmE) and silkworm pupae was confirmed by Western blotting and immunofluorescence assay (IFA) after infection with BmNPV-VP35-VP4. To vaccinate the grass carp by oral route, the silkworm pupae expressing the rVP35-VP4 proteins were converted into a powder after freeze-drying, added to artificial feed at 5% and fed to grass carp (18 ± 1.5 g) for six weeks, and the immune response and protective efficacy in grass carp after oral vaccination trial was thoroughly investigated. This included blood cell counting and classification, serum antibody titer detection, immune-related gene expression and the relative percent survival rate in immunized grass carp. The results of blood cell counts show that the number of white blood cells in the peripheral blood of immunized grass carp increased significantly from 14 to 28 days post-immunization (dpi). The differential leukocyte count of neutrophils and monocytes were significantly higher than those in the control group at 14 dpi. Additionally, the number of lymphocytes increased significantly and reached a peak at 28 dpi. The serum antibody levels were significantly increased at Day 14 and continued until 42 days post-vaccination. The mRNA expression levels of immune-related genes (IFN-1, TLR22, IL-1β, MHC I, Mx and IgM) were significantly upregulated in liver, spleen, kidney and hindgut after immunization. Four weeks post-immunization, fish were challenged with virulent GCRV by intraperitoneal injection. The results of this challenge study show that orally immunized group exhibited a survival rate of 60% and relative percent survival (RPS) of 56%, whereas the control group had a survival rate of 13% and RPS of 4%. Taken together, our results demonstrate that the silkworm pupae powder containing baculovirus-expressed VP35-VP4 proteins could induce both non-specific and specific immune responses and protect grass carp against GCRV infection, suggesting it could be used as an oral vaccine. [ABSTRACT FROM AUTHOR]

The grass carp hemorrhagic disease, caused by the grass carp reovirus (GCRV), has resulted in severe economic losses in the aquaculture industry in China. VP4 and VP35 are outer capsid proteins of GCRV and can induce an immune response in the host. Here, three recombinant baculoviruses, AcMNPV-VP35, AcMNPV-VP4, and AcMNPV-VP35-VP4, were generated to express recombinant VP4 and VP35 proteins from GCRV type II in insect cells by using the Bac-to-Bac baculovirus expression system to create a novel subunit vaccine. The expression of recombinant VP35, VP4, and VP35-VP4 proteins in Sf-9 cells were confirmed by Western blotting and immunofluorescence. Recombinant VP35, VP4, and VP35-VP4 were purified from baculovirus-infected cell lysates and injected intraperitoneally (3 μg/fish) into the model rare minnow, Gobiocypris rarus. After 21 days, the immunized fish were challenged with virulent GCRV. Liver, spleen, and kidney samples were collected at different time intervals to evaluate the protective efficacy of the subunit vaccines. The mRNA expression levels of some immune-related genes detected by using quantitative real-time PCR (qRT-PCR) were significantly upregulated in the liver, spleen, and kidney, with higher expression levels in the VP35-VP4 group. The nonvaccinated fish group showed 100% mortality, whereas the VP35-VP4, VP4, and VP35 groups exhibited 67%, 60%, and 33% survival, respectively. In conclusion, our results revealed that recombinant VP35 and VP4 can induce immunity and protect against GCRV infection, with their combined use providing the best effect. Therefore, VP35 and VP4 proteins can be used as a novel subunit vaccine against GCRV infection. [ABSTRACT FROM AUTHOR]

• Denitrification rates were higher in channel sediments than in riparian bulk soils. • Nitrification and denitrification rates in riparian bulk soils decreased with soil depth. • Riparian topsoils harbored more nitrifying and denitrifying microorganisms than subsoils. • Nitrifying and denitrifying microbial communities were affected by climate and edaphic factors. Nitrogen (N) cycling in rivers is particularly active and dynamic due to excess nutrient inputs worldwide. However, the multidimensional spatial patterns of the activity and community structure of N-cycling microorganisms in rivers remain unclear, limiting our understanding of river ecological functions, especially N removal capacity. Here, we measured the nitrification and denitrification rates and identified nitrifying and denitrifying microorganisms using high-throughput sequencing of archaeal amoA , bacterial amoA, nirK , and nirS genes in channel sediments, riparian rhizosphere soils, and riparian bulk soils of 30 N-polluted rivers across China. Results showed that in the lateral dimension, nitrification rates in sediments did not differ significantly from those in rhizosphere and bulk soils, but denitrification rates were higher in sediments than in bulk soils. However, the archaeal amoA gene abundance in sediments was considerably lower than that in rhizosphere and bulk soils, and bacterial amoA gene abundance in sediments was greater than that in rhizosphere soils. In the vertical dimension, both nitrification and denitrification rates in riparian bulk soils decreased with soil depth, and topsoils harbored more nitrifying and denitrifying microbes than subsoils. Denitrification but not nitrification rates increased with latitude and altitude but decreased with increasing mean annual temperature and precipitation. Overall, these results provide new insights into the multidimensional spatial patterns of river N cycling at a large scale, which is crucial to evaluating the N removal function of global rivers. [Display omitted] [ABSTRACT FROM AUTHOR]

The Chinese sturgeon (Acipenser sinensis) is one of the critically endangered aquatic species in China. It is also among the oldest extant actinopterygian fish species. To advance the characterization of the Chinese sturgeon immune system, we identified the gene encoding the macrophage migration inhibitory factor (MIF), a multifunctional cytokine that contributes to both innate and adaptive immune responses. Molecular and phylogenic analysis indicates the Chinese sturgeon (cs) MIF share a high degree of structural conservation with other MIF sequences and is closely related to other bony fish MIF. At steady state, cs - mif gene is expressed at relatively high levels in the brain, and to a lesser but significant level in liver, spleen, kidney, gut and skin. The spatial expression patterns determined by in situ hybridization indicates a preferential distribution of cs-mif transcripts in the cerebral cortex, the gut epithelium, hematopoietic tissues of kidney, spleen and liver parenchyma, and skin epidermis. Marked increase of cs-mif gene expression was induced by lipopolysaccharide (LPS) stimulation and Aeromonas hydrophila infection in all tested tissues. Furthermore, higher cs-mif transcript levels were detected in the liver, spleen, kidney, gut and skin during stress response resulting from hyperthermia. These results are not only consistent with the expected role of cs- mif gene in innate immunity but also suggest a potential role of this gene in stress response to hyperthermia in the Chinese sturgeon. • Characterization of Chinese sturgeon mif gene and expression patterns. • Higher cs-mif transcript levels were induced by bacterial, LPS and hyperthermia. • A potential role of cs-mif in stress response to hyperthermia. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Antibiotic resistance genes in wetlands across the Tibetan Plateau were analyzed. • Spatial geographical distance did not influence the ARG profile. • Bacterial community was the main driver shaping the ARG diversity and distribution. • Soil moisture and temperature were also positively correlated with ARG abundance. Abstract Antibiotic resistance genes (ARGs) have been identified as emerging pollutants in the environment. However, little information is available for ARGs in natural wetlands at high altitude. In this study, we investigated 32 wetlands across the Qinghai-Tibetan Plateau, with the variation of wetland types, altitude, and environmental factors, to assess the determinant factor of ARGs in this area. ARGs were detected in all the wetlands, ranged from 1.80 × 105 to 1.35 × 107 copies per gram of soils. The ARGs in wetland soils were diverse and abundant, and varied from each site, but the spatial geographical distance did not influence the ARG profile. The mobile genetic elements in wetlands ranged from 3.13 × 103 to 1.02 × 106 copies per gram of soil, indicating the low abundance of mobile genetic elements suggests a lower transfer rate of ARGs between bacteria in the Plateau. Bacterial community composition was the main driver in shaping the ARG diversity and geographic distribution. Soil moisture and temperature were positively correlated with ARG abundance in this region. These results not only provide a better understanding of the background levels of ARGs in the Qinghai-Tibetan Plateau, but also shed light on the influence of climate change and increased human activities on the distribution of ARGs. [ABSTRACT FROM AUTHOR]

Major histocompatibility complex class Ⅰ (MHC Ⅰ) molecules play a vital role in adaptive immune systems in vertebrates by presenting antigens to effector T cells. Understanding the expression profiling of MHC Ⅰ molecules in fish is essential for improving our knowledge of the relationship between microbial infection and adaptive immunity. In this study, we conducted a comprehensive analysis of MHC Ⅰ gene characteristics in Carassius auratus , an important freshwater aquaculture fish in China that is susceptible to Cyprinid herpesvirus 2 (CyHV-2) infection. We identified approximately 20 MHC Ⅰ genes discussed, including U, Z, and L lineage genes. However, only U and Z lineage proteins were identified in the kidney of Carassius auratus using high pH reversed-phase chromatography and mass spectrometry. The L lineage proteins were either not expressed or present at an extremely low level in the kidneys of Carassius auratus. We also used targeted proteomics to analyze changes in protein MHC Ⅰ molecules abundance in healthy and CyHV-2-infected Carassius auratus. We observed that five MHC Ⅰ molecules were upregulated, and Caau -UFA was downregulated in the diseased group. This study is the first to reveal the expression of MHC Ⅰ molecules at a large scale in Cyprinids, which enhances our understanding of fish adaptive immune systems. • Improved protein identification in Carassius auratus using high pH reversed-phase separation. • Most MHC Ⅰ molecules and β2-microglobulin were upregulated in Carassius auratus after CyHV-2 infection. • The accessory molecules involved in the assembly of MHC Ⅰ complex were upregulated after CyHV-2 infection. • The nonclassical U lineage protein Caau -UFA was downregulated in the diseased Carassius auratus. [ABSTRACT FROM AUTHOR]

Ammonium (NH 4 +) oxidation is a key step in nitrogen transformation in ecosystems. Prior to the recent discovery of Feammox (anaerobic NH 4 + oxidation coupled with iron reduction), anammox (anaerobic NH 4 + oxidation coupled with nitrite reduction) was thought of as the only pathway by which anaerobic NH 4 + loss (NH 4 + directly to N 2) occurs in soils. Experimental evidence has confirmed that both anammox and Feammox contribute to anaerobic NH 4 + loss; however, their relative contributions to this process in farmland soils are largely unknown. Therefore, in this study, we examined the seasonal activities of anammox and Feammox in conventional tillage (CT) and no-tillage (NT) soils around Lake Taihu, China. Isotopic tracing experiments showed higher anammox and Feammox rates in summer than in other seasons, and the contribution of Feammox to anaerobic NH 4 + loss from the farmland soils (54.6%–69.3%) was higher than that of anammox. Further, the Feammox rates corresponding to the two soil tillage practices were significantly different, whereas their corresponding anammox rates showed no significant differences. Furthermore, molecular analysis showed that the abundance of Geobacteraceae differed significantly with season and tillage practice, whereas the abundance of anammox bacteria showed no significant differences between CT and NT practices. Structural equation modeling also revealed that the anammox rate was directly or indirectly driven by N availability and season, whereas the Feammox rate was driven by soil moisture content, Fe(III) concentration, Fe(III) reduction rates, tillage practice, and season. Overall, this study enhances understanding regarding anaerobic NH 4 + oxidation in farmland soils and highlight the importance of Feammox in NH 4 + loss in such an ecosystem. [Display omitted] • Feammox contributed more to anaerobic NH 4 + loss than anammox in farmland soils. • Feammox activity was higher in conventional tillage than in no-tillage soils. • Anammox and Feammox activities varied significantly among seasons. • Tillage type and season were the key factors in regulating NH 4 + loss. [ABSTRACT FROM AUTHOR]

• Long-term, repeated flooding reduced soil total N by 17% and total P by 24%. • Soil metal concentrations were higher under disrupted flooding regimes. • Plant diversity and species richness were negatively affected by frequent flooding. • Soil micro-organisms were generally unaffected by flooding regime. The operation of the Three Gorges Reservoir (TGR), the largest hydropower dam in the world, has triggered a dramatic shift in the flooding regimes of sites upstream of the reservoir. Little is known about how disrupted flooding regimes and consequent management approaches might affect the ecological and biogeochemical characteristics of riparian ecosystems. In this study, we evaluated the effects of disruptions to natural flooding regime on basic soil properties, soil nutrient and heavy metal levels, and key characteristics of riparian plant and soil microbial communities. To do this, we used an elevational gradient that encompassed four flooding duration zones (0 (i.e., control), 169, 237, 286 days of flooding per year on average). The disrupted flooding regimes were associated with levels of soil total N and P that were on average 17% and 24% lower, respectively, than those in the non-flooded areas. On the other hand, the concentrations of heavy metals (Hg, Pb, Cu, Zn and Mn) were higher in flood-affected areas than in the non-flooded areas. Increased flooding frequency was also associated with lower plant diversity and species richness relative to non-flooded areas. Thus, disruption of the natural flooding regime had strong and often negative consequences for the ecological and biogeochemical properties of the riparian ecosystems in our study. There was some evidence that riparian plant communities were able to partially recover from prior flooding during a single growing season, even after nine years of repeated flooding, and these recovery trajectories were associated with shifts in soil chemical properties during the same period. However, revegetation efforts had few effects on ecosystem properties or their recovery trajectories following flooding events, suggesting that natural regeneration could be a useful option for the management of these sites. We conclude that the unnatural flooding regimes associated with large scale reservoir development are likely to have profound impacts on the structure and functioning of riparian ecosystems, and these will pose a considerable challenge for environmental management and biodiversity conservation. [ABSTRACT FROM AUTHOR]

Understanding the spatial patterns of dissolved organic matter (DOM) and factors that influence them is crucial for maintaining river ecosystem functions and riverine health, considering the significant role of DOM in water quality and aquatic ecosystems. Nevertheless, there is limited knowledge regarding the spatial variation of DOM bioavailability and the factors driving them in large river systems. This study involved 39 sampling locations along the main stem of the Changjiang River, spanning its entire length (>5000 km) during a dry season. Spatial patterns of DOM were assessed by measurements of DOC concentrations and eight fluorescence DOM indices, namely fluorescence index (FI-A and FI-B), Trytophan/Tyrosine, Humic A, Humic C, humification indices (HIX-A and HIX-B), and Freshness index (β/α). The results revealed that the water DOM in the main stem of the Changjiang River primarily originated from terrestrial sources. A decline in DOM bioavailability was observed from the upper to the lower basin, aligning with the carbon processing prediction rather than the river continuum concept (RCC). The pure effect of physicochemical factors (25.30%) was greater than that of geographic factors (9.40%). The internal transformation processes determined the significant longitudinal decreases of DOM bioavailability. While no significant difference in DOM bioavailability was observed between reaches before and after the dams, the construction of dams was found to improve DOM bioavailability at the subsection scale and reduce the spatial autocorrelation of DOM bioavailability across the entire basin., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Weibo Wang reports financial support was provided by National Natural Science Foundation of China. Quanfa Zhang reports financial support was provided by National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Understanding response of bacterioplankton community responsible for maintaining ecological functions of aquatic ecosystems to environmental disturbance is an important subject. However, it remains largely unclear how bacterioplankton generalists and specialists respond to dredging disturbance. Illumina MiSeq sequencing and statistical analyses were used to evaluate landscape patterns, evolutionary potentials, environmental adaptability, and community assembly processes of generalists and specialists in response to dredging in eutrophic Lake Nanhu. The Proteobacteria and Actinobacteria dominated bacterioplankton communities of generalists and specialists, and abundances of Proteobacteria decreased and Actinobacteria increased after dredging. The generalists displayed higher phylogenetic distance, richness difference, speciation rate, extinction rate, and diversification rate as well as stronger environmental adaptation than that of specialists. In contrast, the specialists rather than generalists showed higher community diversity, taxonomic distance, and species replacement as well as closer phylogenetic clustering. Stochastic processes dominated community assemblies of generalists and specialists, and stochasticity exhibited a larger effect on community assembly of generalists rather than specialists. Our results emphasized that lake dredging could change landscape patterns of bacterioplankton generalists and specialists, whereas the short-term dredging conducted within one year was unable to reverse community difference between generalists and specialists. Our findings extend our understanding of how bacterioplankton generalists and specialists responding to dredging disturbance, and these findings might in turn call on long-term dredging for better ecological restoration of eutrophic lakes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Chinese rice-field eels rhabdovirus (CrERV), belonging to the genus Perhabdovirus in the family Rhabdoviridae, is the causative agent of the haemorrhagic disease of Chinese rice-field eels, Monopterus albus. The present study aims to establish a cell line derived from the kidney of Chinese rice-field eel (CrEK) for the further study of the pathogenic virus. CrEK cells were epithelioid-like and grew well in M199 medium supplemented with 10% foetal bovine serum at 28°C, and the cell line has been subcultured for more than 80 times. Karyotyping analysis of CrEK cells at 25th passage indicated a modal chromosome number of 24. Significant cytopathic effect (CPE) was observed in CrEK cells after infection with CrERV, and the virus titre reached 10 7.8 ± 0.45 TCID 50 /mL. The transmission electron microscopy revealed that there were a large number of virus particles in the cytoplasm of cells. The virus infection in cells was also assayed by using indirect immunofluorescence assay (IFA), fluorescence in situ hybridization (FISH), reverse transcription PCR (RT-PCR) and quantitative real-time reverse transcription-PCR (qRT-PCR). In experimental infection, CrERV cultured by cells could cause over 90% mortality in fish. CrEK represents the first kidney cell line originated from Chinese rice-field eels and be a potential material for investigating the mechanism of virus infection in this fish and the control methods for the disease., (© 2021 John Wiley & Sons Ltd.)

Abstract: To provide information and a basis for improved hepatitis C prevention and treatment, we aimed to determine the distribution of hepatitis C virus (HCV) genotypes among patients with hepatitis C from 4 ethnic minorities in Liaoning Province of China over the past 8 years and analyze and explore the virus' genotype evolution and possible clinical significance.For gene-sequencing, we collected peripheral blood samples of HCV-infected patients belonging to the Korean, Hui, Mongol, and Manchu ethnic minorities in Liaoning Province who were diagnosed at the Second Hospital of Dalian Medical University, Anshan Central Hospital, and the Second People's Hospital of Fuxin City between November 2011 and November 2019. To analyze genotype evolution and possible influencing factors, we determined the ratio of various genotypes. Among the 102 HCV-infected patients from 4 ethnic minorities in Liaoning Province, 46 had gene typing (GT)1b (45.10%), 15 had GT2a (14.71%), 14 had GT3a (13.73%), 13 had GT6a (12.75%), 3 had GT1a (2.94%), and 11 had an unclassified genotype (10.78%). The distribution of various genotypes in the Korean, Mongol, and Manchu ethnic minorities was significantly different (χ2 = 10.788, P = .029; χ2 = 7.846, P = .049; and χ2 = 22.400, P = .000, respectively). All ethnic minorities exhibited >40% of GT1b. In the Korean (14/33) and Manchu (14/30) ethnic minorities, the proportion of GT1b was significantly higher than those of other genotypes (P < .05). The ethnic Koreans had a high proportion of GT3a (18.18%, 6/33), whereas the ethnic Mongolians had a high proportion of GT6a (23.08%, 6/26). GT1a was only found in the Korean (6.06%, 2/33) and Manchu (3.33%, 1/30) ethnic minorities; in the Hui ethnic minority, only 3 genotypes were prevalent: GT1b, GT2, and GT3a. The ethnic minorities in Liaoning Province currently have diverse HCV genotypes; the most prevalent genotype is GT1b, followed by GT2a and GT3a, and the prevalence of GT3 and GT6 has increased. The distribution of HCV genotypes varies across different ethnic minorities. The Korean and Manchu ethnic minorities have the most prevalent genotypes, whereas the Hui ethnic minority has a relatively single distribution of the HCV genotype., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Wetlands play a vital role in removing nitrogen (N) from aquatic environments via the denitrification process, which is regulated by multiple environmental and biological factors. Until now, the mechanisms by which environmental factors and microbial abundance regulate denitrification rates in wetlands under different hydrological conditions remain poorly understood. Here, we investigated sediment potential denitrification rate (PDR) and unamended denitrification rate (UDR), and quantified denitrifier abundance (nirS, nirK, and nosZ genes) in 36 stream, river, pond, and ditch wetland sites along the Dan River, a nitrogen-rich river in central China. The result indicated that ditches had the highest denitrification rates and denitrifier abundance. Both PDR and UDR showed strong seasonality, and were observed to be negatively correlated with water velocity in streams and rivers. Moreover, denitrification rates were significantly related to denitrifier abundance and many water quality parameters and sediment properties. Interestingly, PDR and UDR were generally positively associated with N and carbon (C) availability in streams and rivers, but such correlations were not found in ponds and ditches. Using a scaling analysis, we found that environmental parameters, including Reynolds number, sediment total C ratio, and interstitial space, coupled with relative nirS gene abundance could predict the hotspots of denitrification rates in wetlands with varying hydrologic regimes. Our findings highlight that hydrological conditions, especially water velocity and hydrologic pulsing, play a nonnegligible role in determining N biogeochemical processes in wetlands., Competing Interests: Declaration of competing interest The authors declare that no conflict of interest exists., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Tilapia is one of the most important economic and fastest-growing species in aquaculture worldwide. In 2015, an epidemic associated with severe mortality occurred in adult tilapia in Hubei, China. The causative pathogen was identified as Tilapia parvovirus (TiPV) by virus isolation, electron microscopy, experimental challenge, In situ hybridization (ISH), indirect immunofluorescence (IFA), and viral gene sequencing. Electron microscopy revealed large numbers of parvovirus particles in the organs of diseased fish, including kidney, spleen, liver, heart, brain, gill, intestine, etc. The virions were spherical in shape, non-enveloped and approximately 30nm in diameter. The TiPV was isolated and propagated in tilapia brain cells (TiB) and induced a typical cytopathic effect (CPE) after 3 days post-infection (dpi). This virus was used to experimentally infect adult tilapia and clinical disease symptoms similar to those observed naturally were replicated. Additionally, the results of ISH and IFA showed positive signals in kidney and spleen tissues from TiPV-infected fish. To identify TiPV-specific sequences, the near complete genome of TiPV was obtained and determined to be 4269 bp in size. Phylogenetic analysis of the NS1 sequence revealed that TiPV is a novel parvovirus, forms a separate branch in proposed genus Chapparvovirus of Parvoviridae. Results presented here confirm that TiPV is a novel parvovirus pathogen that can cause massive mortality in adult tilapia. This provides a basis for the further studies to define the epidemiology, pathology, diagnosis, prevention and treatment of this emerging viral disease., Competing Interests: The authors have declared that no competing interests exist.

Inflammatory mediators and inflammatory cells in the inflammatory microenvironment promote the transformation of normal cells to cancer cells in the early stage of cancer, promote the growth and development of cancer cells, and induce tumor immune escape. The monomeric active ingredient β -elemene is extracted from the traditional Chinese medicine Curcuma wenyujin and has been proven to have good anti-inflammatory and antitumor activities in clinical applications for more than 20 years in China. Recent studies have found that this traditional Chinese medicine plays a vital role in macrophage infiltration and M2 polarization, as well as in regulating immune disorders, and it even regulates the transcription factors NF- κ B and STAT3 to alter inflammation, tumorigenesis, and development. In addition, β -elemene regulates not only different inflammatory factors (such as TNF- α , IFN, TGF- β , and IL-6/10) but also oxidative stress in vivo and in vitro. The excellent anti-inflammatory and antitumor effects of β -elemene and its ability to alter the inflammatory microenvironment of tumors have been gradually elaborated. Although the study of monomeric active ingredients in traditional Chinese medicines is insufficient in terms of quality and quantity, the pharmacological effects of more active ingredients of traditional Chinese medicines will be revealed after β -elemene., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Qiang Xie et al.)

ATP-binding cassette, superfamily G, member 2 (ABCG 2 ) has been shown to play an important role in the development of ischemic stroke in European and African American populations. The aim of the present study is to test the hypothesis that there are associations between ABCG 2 polymorphisms and ischemic stroke risk in a Chinese population. We conducted a case-control study including 967 participants with ischemic stroke and 939 stroke-free controls. The rs2231137C > T and rs2231142G > T were genotyped using a TaqMan real-time polymerase chain reaction assay. We found the rs2231137C > T and rs2231142G > T in ABCG 2 were significantly associated with ischemic stroke (sex-, age-, BMI-, SBP-, DBP-adjusted OR = 1.252; 95% CI, 1.035-1.515; P-value = 0.021 and OR = 1.526; 95% CI, 1.085-2.146; P-value = 0.015, respectively). By haplotype analyses, the haplotype T-G still had a strongly significant association with ischemic stroke (OR = 0.806; 95% CI, 0.692-0.939; P-value = 0.00568). Our findings identified the rs2231137C > T and rs2231142G > T polymorphisms of the ABCG 2 as risk factors for ischemic stroke in a Chinese population., (© 2018 John Wiley & Sons Ltd/University College London.)

The upper Han River basin with an area of approximately 95,000 km(2), is the water source area of the Middle Route of China's South to North Water Transfer Project. Thus, water quality in the basin's river network is of great importance. Nutrients including dissolved inorganic nitrogen (DIN), NO(3)(-)-N, NH(4)(+)-N, and dissolved phosphorus (DP) were analyzed in 41 sites during the period of 2005-2006. Cluster analysis (CA), analysis of variance (ANOVA) and general linear models (GLM) were performed to explore their spatio-temporal variations in the basin. The results revealed that the DIN, NO(3)(-)-N and NH(4)(+)-N increased over the 2 year study period, and their concentrations in the wet season was higher than those in the dry season. The seasonal variation in nitrogen was strongly associated with seasonal pattern of precipitation and there was a negative relationship between DP concentration and river flow. Cluster analysis indicated high nutrient contents in the urban and agricultural production areas. The research will help articulate water resource management strategy for the interbasin water transfer project.