Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was ...characterized by "white tail" and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of "white tail" but of non-bacterial origin, the present disease was named as "bacterial white tail disease (BWTD)". Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system.
The purpose of this study is to investigate the effect of probiotics
YYL3 (Lc) and
YYL5 (Lp) on growth performance, innate immunity, disease resistance and intestinal microbiota of channel catfish. A ...total of 252 catfish (67.20 ± 1.46 g) were randomly divided into 3 groups which were fed with basal diet, Lc-added (3.0 × 10
cfu/g) or Lp-added (3.0 × 10
cfu/g) diets, respectively. After 4 weeks of feeding, Lc significantly enhanced the growth and feed utilization of channel catfish compared with the control group (CG). Following that, the catfish were challenged with an intraperitoneal injection of 200 μL of the pathogenic
(2.0 × 10
cfu/mL), the relative percent survival of Lc and Lp were 38.28% and 12.76%, respectively. High-throughput sequencing indicated Lc and Lp reduced the alpha diversity of the intestinal microbiota in channel catfish.
were overwhelming in the guts during probiotics treatment, but almost vanished away after 2 weeks post-cessation of probiotics administration. Compared to CG, Lc and Lp resulted in an increased abundance of
and decreased amount of
. Functional analysis revealed that Lc treatment upregulated the relative abundance of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways including lipid metabolism, metabolism of other amino acids, metabolism of terpenoids and polyketides, xenobiotics biodegradation and metabolism, and nucleotide metabolism. Combined, our data revealed that Lc, as a feed additive at 3.0 × 10
cfu/g, could promote the growth performance, disease resistance and dramatically change the composition of intestinal microbiota of channel catfish.
Antibiotic resistance has become a serious global problem and is steadily increasing worldwide in almost every bacterial species treated with antibiotics. In aquaculture, the therapeutic options for ...the treatment of A. hydrophila infection were only limited to several antibiotics, which contributed for the fast-speed emergence of drug tolerance. Accordingly, the aim of this study was to establish a medication regimen to prevent drug resistant bacteria. To determine a rational therapeutic guideline, integrated pharmacodynamics and pharmacokinetics parameters were based to predict dose and dosage interval of enrofloxacin in grass carp Ctenopharyngodon idella infected by a field-isolated A. hydrophila strain.
The pathogenic A. hydrophila strain (AH10) in grass carp was identified and found to be sensitive to enrofloxacin. The mutant selection window (MSW) of enrofloxacin on isolate AH10 was determined to be 0.5-3 μg/mL based on the mutant prevention concentration (MPC) and minimum inhibitory concentration (MIC) value. By using high-performance liquid chromatography (HPLC) system, the Pharmacokinetic (PK) parameters of enrofloxacin and its metabolite ciprofloxacin in grass carp were monitored after a single oral gavage of 10, 20, 30 μg enrofloxacin per g body weight. Dosing of 30 μg/g resulted in serum maximum concentration (Cmax) of 7.151 μg/mL, and concentration in serum was above MPC till 24 h post the single dose. Once-daily dosing of 30 μg/g was determined to be the rational choice for controlling AH10 infection and preventing mutant selection in grass carp. Data of mean residue time (MRT) and body clearance (CLz) indicated that both enrofloxacin and its metabolite ciprofloxacin present similar eliminating rate and pattern in serum, muscle and liver. A withdraw time of more than 32 d was suggested based on the drug eliminating rate and pharmacokinetic model described by a polyexponential equation.
Based on integrated PK/PD parameters (AUC/MIC, Cmax/MIC, and T>MPC), the results of this study established a principle, for the first time, on drawing accurate dosing guideline for pharmacotherapy against A. hydrophila strain (AH10) for prevention of drug-resistant mutants. Our approach in combining PK data with PD parameters (including MPC and MSW) was the new effort in aquaculture to face the challenge of drug resistance by drawing a specific dosage guideline of antibiotics.
Recent studies have revealed that the use of bdellovibrios is an alternative to control bacteriosis. However, no bdellovibrios are available against
Aeromonas hydrophila infections in sturgeons. In ...the present study, a potential
Bdellovibrio strain F16 was isolated from sturgeon gut samples, using a sturgeon-pathogenic
A. hydrophila as the prey bacterium. It was initially identified as a
Bdellovibrio strain using morphological characteristics and specific PCR amplification, and confirmed to be
Bdellovibrio sp. strain ETB (GenBank Accession No.
DQ302728) and
Bdellovibrio bacteriovorus strain SRA9 (GenBank Accession No.
AF263833) by phylogenetic analysis. In addition, it was shown to be safe for mammalians and sturgeons, had a wide prey range, and exhibited significant bacteriolytic effects on the pathogenic
A. hydrophila. To the best of our knowledge, this is the first report on a promising gut
Bdellovibrio strain against pathogenic
A. hydrophila.
Deltamethrin is an important pesticide widely used against ectoparasites. Deltamethrin contamination has resulted in a threat to the healthy breeding of the Chinese mitten crab, Eriocheir sinensis. ...In this study, we investigated transcriptional responses in the hepatopancreas of E. sinensis exposed to deltamethrin. We obtained 99,087,448, 89,086,478, and 100,117,958 raw sequence reads from control 1, control 2, and control 3 groups, and 92,094,972, 92,883,894, and 92,500,828 raw sequence reads from test 1, test 2, and test 3 groups, respectively. After filtering and quality checking of the raw sequence reads, our analysis yielded 79,228,354, 72,336,470, 81,859,826, 77,649,400, 77,194,276, and 75,697,016 clean reads with a mean length of 150 bp from the control and test groups. After deltamethrin treatment, a total of 160 and 167 genes were significantly upregulated and downregulated, respectively. Gene ontology terms "biological process," "cellular component," and "molecular function" were enriched with respect to cell killing, cellular process, other organism part, cell part, binding, and catalytic. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes showed that the metabolic pathways were significantly enriched. We found that the CYP450 enzyme system, carboxylesterase, glutathione-S-transferase, and material (including carbohydrate, lipid, protein, and other substances) metabolism played important roles in the metabolism of deltamethrin in the hepatopancreas of E. sinensis. This study revealed differentially expressed genes related to insecticide metabolism and detoxification in E. sinensis for the first time and will help in understanding the toxicity and molecular metabolic mechanisms of deltamethrin in E. sinensis.
BACKGROUND: Praziquantel (PZQ) is an effective pesticide against monogeneans. Its pharmacokinetics in fish may be affected by water environment and temperature. The present study was designed to ...compare the pharmacokinetics, tissue distribution, and elimination of PZQ in freshwater-acclimated grass carp and brackish water cultured grass carp. Plasma and tissue PZQ concentrations were determined after a single 10 mg/kg oral PZQ dose. RESULTS: The datas of plasma and tissues drug concentration was calculated by the software SPSS 13.0. According to the One-Way ANOVA, the results showed that the salinity had a significant effect on the drug concentration of plasma (p < 0.01), muscle (p < 0.01), liver (p < 0.01) and kidney (p < 0.01) in the all sampling time points between the brackish water grass carps and the freshwater grass carps, wherein, PZQ plasma and tissue concentrations in the brackish water group were constantly lower than that in the freshwater group. The peak PZQ levels of plasma, muscle, liver, and kidneys in the brackish water group were 0.76 μg/ml, 0.51 μg/g, 2.7 μg/g, and 2.99 μg/g, respectively; and that in the freshwater group were 0.91 μg/ml, 0.62 μg/g, 3.87 μg/g, and 3.39 μg/g, respectively. The elimination half-lives (t₁/₂ᵦ) in plasma and all tissues of the freshwater group were significantly longer than that in the brackish water group. The elimination half-lives (t₁/₂ᵦ) of plasma, muscle, liver and kidneys in brackish water grass carps were 56.46, 36.17, 15.31, and 132.64 h, respectively; and that in the freshwater grass carps were 71.15, 44.88, 23.86, and 150.23 h, respectively. CONCLUSION: These findings indicate that water environment affects the tissue distribution and elimination of PZQ in grass carps, the elimination in brackish water grass carps is more rapid than that in fresh water grass carps and tissue concentrations of brackish water grass carps are lower than that in freshwater grass carps after orally administrating the same dosage at the same water temperature. We speculate that the main excretion pathway of the drug is through renal elimination, and the decreased kidney function in brackish water grass carps is likely responsible for the considerable difference in pharmacokinetics between the two groups of grass carps.
Ciprofloxacin (CPFX) residues in fishery products were dangerous for human health and still remain a big challenge in China. However, there are a few available assays to detect specifically CPFX ...residues in fishery products. This study aimed at generating CPFX-specific monoclonal antibodies (mAbs) and developing a competitive indirect enzyme-linked immunosorbent assay (ci-ELISA) for the sensitive and specific detection of CPFX residues in fishery products. Firstly, the CPFX was conjugated with BSA and the conjugates were immunized to Balb/c mice. After characterizing anti-CPFX sera, we generated hybridoma cell lines and found that one hybridoma clone, 1C9, produced anti-CPFX mAb. Characterization of IC9 mAb revealed that it belonged to IgG2a, with an affinity of 3.75
×
10
10
mol/l for CPFX. Furthermore, we developed ic-ELISA using 150
ng/ml of CPFX-OVA for coating antigen and 0.22
μg of mAb. We found that this assay detected CPFX at 45.25
ng/ml and had 84.60% of cross-activity to enrofloxacin (ENR), but not to ofloxacin, levofloxacin, difloxacin, sarafloxacin, furacilin, chloramphenicol and nalachite green. Using this assay, we detected the CPFX in fishery products prepared with recovery rates from 80.57% to 94.61% and relative standard deviation (RSD) varying from 1.78% to 8.02%, similar to that by HPLC analysis. These data, together the protocol for the preparation of fishery products, indicate that the ic-ELISA is able to detect CPFX and ENR residues in fishery products sensitively and specifically within 2
h. Therefore, this assay can be used for monitoring CPFX and ENR in commercial fishery products, improving the safety of commercial meats in China.
Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) that recognize pathogen associated molecular patterns (PAMPs) and play an important role in the antiviral response. To ...determine the effect of common carp TLR9 (CcTLR9) overexpression on the expression of down-stream interferon associated immune factors in epithelioma papulosum cyprini (EPC) cells, may provide useful information for the further investigation on the anti-virus effect mediated by TLR9 in fish. In this study, we constructed an overexpression vector, pEGFP-N1-CcTLR9, by cloning the CcTLR9 gene and inserting it into an expression vector pEGFP-N1. Both plasmids DNA of pEGFP-N1 and pEGFP-N1-CcTLR9 were transfected into EPC cells, and the expression of IRF3, IRF7, ISG15, Mx1, PKR and Viperin mRNA at 0, 6, 12, 24, 48 and 72h post-transfection were determined by real-time quantitative PCR (Q-PCR). Overexpression of the CcTLR9 gene in EPC cells upregulates the expression of IRF3, IRF7, ISG15, Mx1, PKR, and Viperin mRNA, and this was more significant for Viperin, ISG15, and IRF7, and least significant for PKR. Thus, fish TLR9 activates IRF7 signaling to induce I-IFN secretion and the subsequent upregulation of IFN-stimulated genes.
Malachite green （MG）, a dye, is an antifungal agent that has been used to treat and prevent fish diseases. It is metabo- lized into reduced leucomalachite green forms （LMG） that may reside in fish ...muscles for a long period, thus being harmful to human health. The aim of this study was to develop a competitive and direct enzyme-linked immunosorbent assay （ELISA） to detect MG and LMG specifically. The monoclonal antibody （mAb） to LMG was generated using a hybridoma technique. The obtained mAb showed good cross-reactivity （CR） to malachite green （MG）, but not to crystal violet （CV） and Brilliant Green （BG）. The mAb was used to develop a fast detecting ELISA of MG and LMG in fish. By introducing the conjugation LMG-HRP, the detection capability was 0.37ngmL-1 for MG and LMG. The mean recovery from spiked grass carp tissues ranged from 76.2% to 82.9% and the coeffi- cients of variation varied between 1.8% and 7.5%. The stable and efficient monoclonal cell line obtained is a sustainable source of sensitive and specific antibody to MG and LMG.
PDF
