Rhodobacter sphaeroides supplementation improves defense ability of Chinese mitten crab Eriocheir sinensis against Shewanella putrefaciens infection via intestinal flora and metabolism regulation.

Shewanella putrefaciens is a vital bacterial pathogen implicated in serious diseases in Chinese mitten crab Eriocheir sinensis. Yet the use of probiotics to improve the defense ability of E. sinensis against S. putrefaciens infection remains poorly understood. In the present study, the protective effect of dietary R. sphaeroides against S. putrefaciens infection in E. sinensis was evaluated through antioxidant capability, immune response, and survival under bacterial challenge assays, and its protective mechanism was further explored using a combination of intestinal flora and metabolome assays. Our results indicated that dietary R. sphaeroides could significantly improve immunity and antioxidant ability of Chinese mitten crabs, thereby strengthening their disease resistance with the relative percentage survival of 81.09% against S. putrefaciens. In addition, dietary R. sphaeroides could significantly alter the intestinal microbial composition and intestinal metabolism of crabs, causing not only the reduction of potential threatening pathogen load but also the increase of differential metabolites in tryptophan metabolism, pyrimidine metabolism, and glycerophospholipid metabolism. Furthermore, the regulation of differential metabolites such as N-Acetylserotonin positively correlated with beneficial Rhodobacter could be a potential protection strategy for Shewanella infection. To the best of our knowledge, this is the first study to illustrate the protective effect and mechanism of R. sphaeroides supplementation to protect E. sinensis against S. putrefaciens infection.

Identification of Vibrio ponticus as a bacterial pathogen of coral trout Plectropomus leopardus.

Vibrio ponticus is a vital pathogen with potential danger for aquaculture animals. Yet V. ponticus pathogenic to the coral trout Plectropomus leopardus is still unknown. In this study, a virulent bacterial strain, temporarily named DX2, was isolated from diseased coral trout suffering liver necrosis with cell vacuolar degeneration, and was identified molecularly and phenotypically as V. ponticus. Besides, the DX2 isolate showed an LD50 value of 6.64×105 CFU mL-1, developed multiple resistances to cephalosporins, macrolides, penicillins, peptides, and sulfonamides antimicrobials, and was highly susceptible to doxycycline and florfenicol in aquaculture use. To the best of our knowledge, this is the first report of the pathogenicity of V. ponticus to the coral trout, and the findings provide a reference for the control of pathogenic V. ponticus in the coral trout.

The features of the coastal fronts in the Eastern Guangdong coastal waters during the downwelling-favorable wind period.

A coastal front was detected in the eastern Guangdong (EGD) coastal waters during a downwelling-favorable wind period by using the diffuse attenuation coefficient at 490 nm (Kd(490)). Long-term satellite data, meteorological data and hydrographic data collected from 2003 to 2017 were jointly utilized to analyze the environmental factors affecting coastal fronts. The intensities of the coastal fronts were found to be associated with the downwelling intensity. The monthly mean Kd(490) anomalies in shallow coastal waters less than 25 m deep along the EGD coast and the monthly mean Ekman pumping velocities retrieved by the ERA5 dataset were negatively correlated, with a Pearson correlation of - 0.71. The fronts started in October, became weaker and gradually disappeared after January, extending southwestward from the southeastern coast of Guangdong Province to the Wanshan Archipelago in the South China Sea (SCS). The cross-frontal differences in the mean Kd(490) values could reach 3.7 m-1. Noticeable peaks were found in the meridional distribution of the mean Kd(490) values at 22.5°N and 22.2°N and in the zonal distribution of the mean Kd(490) values at 114.7°E and 114.4°E. The peaks tended to narrow as the latitude increased. The average coastal surface currents obtained from the global Hybrid Coordinate Ocean Model (HYCOM) showed that waters with high nutrient and sediment contents in the Fujian and Zhejiang coastal areas in the southern part of the East China Sea could flow into the SCS. The directions and lengths of the fronts were found to be associated with the flow advection.

Full-length transcriptome sequencing combined with RNA-seq analysis revealed the immune response of fat greenling (Hexagrammos otakii) to Vibrio harveyi in early infection.

Fat greenling (Hexagrammos otakii) is an important commercial marine fish species cultured in northeast Asia, but its available gene sequences are limited. Vibrio harveyi is a causative agent of vibriosis in fat greenling and also causes severe losses to the aquaculture industry in China. In order to obtain more high-quality transcript information and investigate the early immune response of fat greenling against V. harveyi, the fish were artificially infected with V. harveyi, and five sampling points were set within 48 h. Iso-Seq combined with RNA-Seq were applied in the comprehensive transcriptome analysis of V. harveyi-infected fat greenling. Total 42,225 consensus isoforms were successfully extracted from the result of Iso-Seq, and more than 19,000 ORFs were predicted. In addition, total three modules were identified by WGCNA which significantly positive correlated to the infection time, and the KEGG analysis showed that the immune-related genes in these modules mainly enriched in TLR signaling pathway, NF-κB signaling pathway and Endocytosis. The activation of inflammation and endocytosis was the most significant characteristics of fat greenling immune response during the early infection. Based on the WGCNA, a series of high-degree nodes in the networks were identified as hub genes. The protein structures of cold-inducible RNA-binding protein (CIRBP), poly [ADP-ribose] polymerase 1 (PARP1) and protein arginine N-methyl transferase 1 (PRMT1) were subsequently found to be highly conserved in vertebrate, and the gene expression pattern of CIRBP, PARP1, PRMT1 and a part of TLR/NF-κB pathway-related genes indicated that these proteins might have similar biological functions in regulation of inflammatory response in teleost fish. The results of this study provided the first systematical full-length transcriptome profile of fat greenling and characterized its immune responses in early infection of V. harvey, which will serve as the foundation for further exploring the molecular mechanism of immune defense against bacterial infection in fat greenling.

Recombinant outer membrane protein C of Aeromonas salmonicida subsp. masoucida, a potential vaccine candidate for rainbow trout (Oncorhynchus mykiss).

Aeromonas salmonicida subsp. masoucida (ASM) is an important bacterial pathogen of salmonid fish, which can cause huge economic losses to the fish farming industry. In order to screen effective vaccine candidate proteins, four outer membrane proteins of ASM, including OmpA, OmpC, OmpK and OmpW, were selected and recombinantly expressed in Escherichia coli. The result of western blotting showed that these four recombinant proteins could be recognized by rainbow trout anti-ASM antibodies. The immune protective effects of the four rOMPs were also investigated, and the relative percentage survival (RPS) of rOmpA, rOmpC, rOmpK and rOmpW were 71.1%, 81.6%, 55.3% and 42.1%, respectively. The RPS of rOmpC was significantly higher than the other three rOMPs, so the immune responses of rainbow trout induced by rOmpC were further investigated. The results showed that vaccination with rOmpC could significantly induced the production of specific serum antibodies and proliferation of sIg + lymphocytes in peripheral blood. Meanwhile, RT-qPCR analysis showed that rOmpC could significantly enhance the expression of the MHC-II, TCR, CD4, CD8, IL-8 and IgM genes compared with the BSA immunized group. These results demonstrated that rOmpC could induce strong humoral immune response in rainbow trout and provided effective immune protection against ASM challenge, which indicated that OmpC is a promising vaccine candidate against Aeromonas salmonicida infection.

Transcriptome analysis of immune response in fat greenling (Hexagrammos otakii) against Vibrio harveyi infection.

Fat greenling (Hexagrammos otakii) is an important aquaculture fish species in northern China. Unfortunately, Vibrio infections have caused considerable losses to the fat greenling aquaculture industry. However, the study on immune response of fat greenling against Vibrio species has not been reported yet. In this paper, the immune response of fat greenling against V. harveyi at gene expression level was studied by transcriptome analysis. A total of 189753 high-quality unigenes with a N50 length of 672bp were obtained by transcriptome profiling, which provided abundant data for the future study of fat greenling. Comparative analysis showed that 5425 differentially expressed genes (DEGs) were identified on day 3 post-infection (3dpi), containing 1837 up-regulated and 3588 down-regulated genes. Further annotation and analysis revealed that the DEGs were enriched in complement and coagulation cascades, ribosome, oxidative phosphorylation, glycine, serine and threonine metabolism and peroxisome proliferator-activated receptor (PPAR) signaling pathway. These pathways were mainly associated with phagocytosis and pathogen clearance, rarely involved in bacteria adhesion and pathogen identification, which suggested that the host might begin to clear and kill the invading bacteria on 3dpi. The research might provide a valuable resource to further study immune response and suggest strategies against V. harveyi infection in fat greenling.

Estimation of suspended particulate matter in turbid coastal waters: application to hyperspectral satellite imagery.

An empirical algorithm is proposed to estimate suspended particulate matter (SPM) ranging from 0.675 to 25.7 mg L-1 in the turbid Pearl River estuary (PRE). Comparisons between model predicted and in situ measured SPM resulted in R2s of 0.97 and 0.88 and mean absolute percentage errors (MAPEs) of 23.96% and 29.69% by using the calibration and validation data sets, respectively. The developed algorithm demonstrated the highest accuracy when compared with existing ones for turbid coastal waters. The diurnal dynamics of SPM was revealed by applying the proposed algorithm to reflectance data collected by a moored buoy in the PRE. The established algorithm was implemented to Hyperspectral Imager for the Coastal Ocean (HICO) data and the distribution pattern of SPM in the PRE was elucidated. Validation of HICO-derived reflectance data by using concurrent MODIS/Aqua data as a benchmark indicated their reliability. Factors influencing variability of SPM in the PRE were analyzed, which implicated the combined effects of wind, tide, rainfall, and circulation as the cause.

Adjuvant and immunostimulatory effects of LPS and ß-glucan on immune response in Japanese flounder, Paralichthys olivaceus.

In order to investigate the adjuvant and immunostimulatory effects of LPS and ß-glucan, a highly effective vaccine candidate for Edwardsiella tarda known as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was recombinantly expressed in Escherichia coli, which was intramuscularly injected into Japanese flounder alone or containing LPS or ß-glucan. ELISA analysis of sera showed that the fish immunized with rGAPDH containing LPS or ß-glucan had significant higher antibody titers than rGAPDH immunization group at day 14 and 30 (P<0.05). Flow cytometric analysis showed that the surface immunoglobulin positive (sIg+) lymphocytes percentages in head kidney of the immunized fish exhibited significant higher than the fish of control group at day 14 and 30, and immunization with rGAPDH containing LPS or ß-glucan could induce significant higher sIg+ percentages than immunization with rGAPDH alone. Simultaneously, the expressions of genes coding for immunoregulatory molecules involved in innate and acquired responses, including IFN-γ, IL-1ß, IL-6, TNF-α, TCRα, IgM, C-type lysozyme and MHC-IIα were analyzed by quantitative PCR. The transcription levels of all selected genes except TNF-α displayed up-regulation after immunization, and immunization with rGAPDH containing LPS or ß-glucan could induce significant higher levels than that induced only by rGAPDH. Moreover, to investigate the protection against infection, challenge with E. tarda was performed at day 30 after immunization. Fish immunized with rGAPDH containing ß-glucan exhibited the highest relative percentage survival (RPS) of 63% compared to the other groups. These results indicated that LPS and ß-glucan employed as co-immunostimulatory molecules could significantly trigger the innate and acquired immune responses in Japanese flounder.

[Validation and analysis of water column correction algorithm at Sanya Bay].

Water column correction has been a substantial challenge for remote sensing. In order to improve the accuracy of coastal ocean monitoring where optical properties are complex, optical property of shallow water at Sanya Bay and the suitable water column correction algorithms were studies in the present paper. The authors extracted the bottom reflectance without water column effects by using a water column correction algorithm which is based on the simulation of the underwater light field in idealized water. And we compared the results which were calculated by the model and Christian's model respectively. Based on a detailed analysis, we concluded that: Because the optical properties of Sanya Bay are complex and vary greatly with location, Christian's model lost its advantage in the area. Conversely, the bottom reflectance calculating by the algorithm based on the simulation of the underwater light field in idealized water agreed well with in situ measured bottom reflectance, although the reflectance was lower than in situ measured reflectance value between 400 and 500 nm. So, it is reasonable to extract bottom information by using the water column correction algorithm in local bay area where optical properties are complex.

[The analyses on dust pollution of one underground iron mine from 1991 to 2010].

OBJECTIVE: The main purpose of this work was to give the evidence of reasonable and feasible dust control measures which will be taken in the future by analyzing the trend of dust concentration from 1991 to 2010 and identifying working faces with the severe dust contamination in one underground iron mine. METHODS: The data was from routine monitoring between the years 1991 and 2010, which enclosed the total dust concentrations and silica contents. China National Standard of Occupational exposure limits for hazardous agents in the workplace used to judge whether the dust concentration exceeded the National Standard. RESULTS: The general trend of total dust concentration from 1991 to 2010 was decreased, especially maximum and average levels. The highest exceeding rate was 43.16% in 1993 and the best years were 2009 and 2010, but the exceeding rates were still over 30%. The dust exposure levels varied with different work faces. The mining and supporting were the most severe dust pollution faces which the highest ultra exceeding rates were 51.61% and 51.48% and the maximum exceeding times were 64.6 and 16.4 respectively. The next was constructing face with 40.23% exceeding rate and 24.6 times more than standard. CONCLUSION: The trend of total dust concentration from 1991 to 2010 was decreased, but the dust exceeding rate was still high. The strong measures should be taken to control the dust pollution in this iron mine, especially mining and supporting faces.

[Progress in Teflon AF LWCC/LCW applications].

Teflon AF is chemically very inert, quite physically and optically stable, a highly vapor-permeable polymer with optical transparency through much of the UV-Vis region and with an RI lower than that of water, so Teflon AF LWCC/LCW (Long path-length liquid waveguide capillary cell/liquid core waveguides) has been used with a range of different detection techniques, including absorbance spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and gas sensor. The present article describes the properties and the aspects of Teflon AF LWCC/LCW instrumentation and applications. And finally,the future prospect and outlook of Teflon AF LWCC/LCW is also discussed.