Fish Serum Research Articles

Co-Cr mixed spinel oxide nanodots anchored on nitrogen-doped carbon nanotubes as catalytic electrode for hydrogen peroxide sensing

Hydrogen peroxide (H2O2) is a significant biomarker in physiological processes. Abnormal levels of H2O2 are considered to be closely related to some acute diseases. Therefore, it is important to monitor the H2O2 levels in bio-samples. Herein, we present a novel non-enzymatic electrochemical H2O2 sensor based on the excellent electrocatalytic performance of a composite comprising Zn-Cr-Co ternary spinel metal oxide nanodots (ZnCrCoO4) anchored on the surface of nitrogen-doped carbon nanotubes (NCNTs), denoted as ZnCrCoO4/NCNTs, toward H2O2 reduction. ZnCrCoO4/NCNTs were synthesized using a facile one-pot hydrothermal strategy. The enhanced electrocatalytic performance of ZnCrCoO4 is resulted from the partial substitution of Co in spinel zinc cobaltate (ZnCo2O4) with Cr, which modifies the CoO electronic structure and enhances electroconductivity. The ZnCrCoO4/NCNTs-based H2O2 sensor exhibited a wide quantitative detection range from 1 to 7330 μM with a detection limit of 1 μM. The sensor showed excellent reproducibility and selectivity for H2O2 sensing. In addition, remarkable recoveries were obtained for H2O2-spiked fish serum samples. These results demonstrated that the as-developed sensor has a great potential in monitoring H2O2 levels in practical applications.

Lactobacillus acidophilus Antimicrobial Peptide Is Antagonistic to Aeromonas hydrophila.

We identified an antimicrobial peptide (AMP) from Lactobacillus acidophilus that was antagonistic to Aeromonas hydrophila. In vitro studies such as well-diffusion and field trials revealed that the AMP was active against A. hydrophila. The field trials of AMP using A. hydrophila-infected Channa striatus with a mannone oligosaccharide (MOS) prebiotic, A. hydrophila antigens, A. hydrophila-infected fish serum, L. acidophilus, and Lactobacillus cell free-supernatant (LABS-CFS) on an indicator organism further revealed that the antimicrobial agent could protect C. striatus. Other than the AMP, none of the above were able to eliminate the infectious agent A. hydrophila, and were only able to delay the death rate for 3–4 days. Thus, we conclude that the AMP is antagonistic to A. hydrophila and may be used for treatment of A. hydrophila infections. Subsequent L. acidophilus whole-genome sequence analyses enabled an understanding of the (probable) gene arrangement and its location on the chromosome. This information may be useful in the generation of recombinant peptides to produce larger quantities for treatment.

Mediation of Mucosal Immunoglobulins in Buccal Cavity of Teleost in Antibacterial Immunity.

The buccal mucosa (BM) of vertebrates is a critical mucosal barrier constantly exposed to rich and diverse pathogens from air, water, and food. While mammals are known to contain a mucosal associated lymphoid tissue (MALT) in the buccal cavity which induces B-cells and immunoglobulins (Igs) responses against bacterial pathogens, however, very little is known about the evolutionary roles of buccal MALT in immune defense. Here we developed a bath infection model that rainbow trout experimentally exposed to Flavobacterium columnare (F. columnare), which is well known as a mucosal pathogen. Using this model, we provided the first evidence for the process of bacterial invasion in the fish BM. Moreover, strong pathogen-specific IgT responses and accumulation of IgT+ B-cells were induced in the buccal mucus and BM of infected trout with F. columnare. In contrast, specific IgM responses were for the most part detected in the fish serum. More specifically, we showed that the local proliferation of IgT+ B-cells and production of pathogen-specific IgT within the BM upon bacterial infection. Overall, our findings represent the first demonstration that IgT is the main Ig isotype specialized for buccal immune responses against bacterial infection in a non-tetrapod species.

Prolactin peptide (pPRL) induces anti-prolactin antibodies, ROS and cortisol but suppresses specific immune responses in rainbow trout

Prolactin has several immune functions in fish however, the effects on innate and specific components of rainbow trout immunity are currently unknown. Therefore in this study, prolactin peptide (pPRL) injection in rainbow trout generated anti-PRL antibodies that were confirmed through Western blot assays of fish brain tissue extract. At the same time, this group of fish was immunized with a viral antigen (VP2) and the specific antibody titer generated by the rainbow trout was subsequently determined, as well as the sero-neutralizing capacity of the antibodies. Interestingly, this group of fish (pPRL-VP2) generated approximately 150% less antibodies compared with fish immunized only with the viral antigen (VP2), and pPRL-VP2 fish increased their cortisol level by 4 times compared to the control. Additionally, through qPCR assay, we determined that the pPRL-VP2 fish group decreased pro-inflammatory transcript expression, and the serum of these (pPRL-VP2) fish stimulated ROS production in untreated fish leukocytes, a phenomenon that was blocked by the pharmacological cortisol receptor inhibitor (RU486). Collectively, this is the first report that indicates that pPRL could modulate both components of immunity in rainbow trout.

Establishment of Conditions for Long-Term Maintenance of Primary Embryonic Cell Cultures from Olive Flounder Paralichthys olivaceus.

Primary cell culture is a sufficient method frequently used to study the cellular properties and mechanisms of isolated cells in a controlled environment. In this study, an embryonic cell line (FGBC8) derived from the blastula stages of embryos of olive flounder Paralichthys olivaceus was developed. Furthermore, conditions for optimal long-term maintenance of this primary embryonic cell culture were investigated. Morphologically, FGBC8 cells were composed primarily of epithelial-like cells. FGBC8 cells were subcultured for >160 passages over ~830 days. The doubling time of FGBC8 cells was 73.8 h, and the modal diploid chromosome number was 48. FGBC8 cells transfected with green fluorescence protein (GFP)-expression plasmid exhibited a strong signal 48 h after transfection. Consequently, we demonstrated that fish serum is a crucial supplement for the long-term survival and maintenance of comparable morphology in these primary embryonic cells. Our results can be used as a guide for primary embryonic cell cultures for other fish species and may be useful for cell biotechnological applications.

Effects of dietary proline on swim bladder collagen synthesis and its possible regulation by the TGF‐β/Smad pathway in spotted drum, Nibea diacanthus

Swim bladder is an ideal source of collagen production in fish for improved human health. Proline (Pro) is the main proteinogenic amino acid needed for collagen production. However, the effects of Pro supplementation on the swim bladder collagen synthesis have rarely been evaluated in fish. We determined the effects of dietary Pro supplementation on swim bladder collagen synthesis and its possible signalling pathway in spotted drum, Nibea diacanthus. A total of 450 N. diacanthus (100 ± 3.05 g) were randomly assigned into six treatments and fed with diets supplemented with different levels of Pro (0, 2.5, 5, 7.5, 10 and 12.5 g/kg of dry diet, hereafter P0, P1, P2, P3, P4 and P5, respectively) for 8 weeks. At the end, we evaluated collagen synthesis in swim bladder and the expression of genes related to TGF-β/Smad pathway in the fish. Dietary Pro levels increased significantly the contents of crude protein, total collagen (TC) and the levels of some amino acids in swim bladder than the control diet (p < .05). The optimum amount of dietary Pro inclusion in diets for swim bladder collagen synthesis in N. diacanthus was 7.6 and 7.5 g/kg based on crude protein and TC in swim bladder, respectively. Dietary Pro levels increased significantly the proline 4-hydroxylase (P4H) content in fish serum, swim bladder, muscle and liver tissues than control (p < .05). The relative expression of collagen type I alpha 1 (COL1A1), alpha 2 (COL1A2) and mothers against decapentaplegic homolog 2 (Smad2) genes in liver and swim bladder initially increased significantly as the concentration of Pro and later decreased (p < .05). Similarly, the relative expression of transforming growth factor beta (TGF-β), P4Ha2 and P4Ha3 genes in the swim bladder increased significantly as dietary Pro levels increased (p < .05). Using K-means clustering analysis, dietary proline partly promoted collagen accumulation in swim bladder through upregulation of Smad2 and TGF-βRT genes. Taken together, Pro affected the collagen metabolism in swim bladder, probably by regulating the TGF-β/Smad pathway, most likely via transient overexpression of Smad2 gene.

Blood loss induces l-amino acid oxidase gene expression in the head kidney of the red-spotted grouper, Epinephelus akaara

In fish, the innate immune system is more important than the adaptive immune system because it responds quickly and nonspecifically to protect against pathogens. Thus, a variety of innate immune molecules have been found in fish. Recently, l-amino acid oxidases (LAOs) were discovered as a new member of the antibacterial protein from fish skin mucus and serum. In this study, we newly found an antibacterial LAO in red-spotted grouper (Epinephelus akaara) serum. It showed a broad range of substrate specificity with aromatic and hydrophobic amino acids. The grouper LAO gene had a low expression level in the kidney under normal conditions; however, it was significantly upregulated by blood loss 1 day after bleeding. In addition, the LAO activity in the serum recovered within 3 days in the same experiment. This quick recovery may indicate that the LAO is an essential innate immune molecule in the whole grouper body.

Effication of Viral Nervous Necrosis DNA as Vaccines for Cromileptes altivelis

Viral nervous necrosis (VNN) is a disease that often infects groupers. It has caused mass death in more than 34 species of marine fish. DNA vaccination might become a solution againts the infection. The construction of the pmBA-CP DNA vaccine consisting of the beta-actin promoter of medaka fish (Oryzias latipes) and capsid protein (CP) encoding VNN RNA2 has been made in previous studies. This study aimed to test the efficacy of the pmBA-CP DNA vaccine for VNN. The experiment consisted of two stages, namely (1) detection of anti-VNN antibody induction in vaccinated fish using ELISA, and (2) challenge test for fish vaccinated with the VNN virus. Grouper (body length 8 cm to 10 cm) were divided into two groups with a density of 5 fish 60 L–1. The fish in the first group were vaccinated with pmBA-CP intramuscularly at a dose of 12.5 µg per fish, while the second group of fish were not vaccinated. Antibody titer testing was carried out before treatment, and 1 d, 7 d, 14 d, 21 d, 28 d, and 35 d after vaccination. The challenge test was carried out on the 60th day after vaccination. The results showed that the S / P ratio in the vaccinated fish serum was higher than unvaccinated fish at 21 d to 35 d post-vaccination. DNA vaccination was able to induce anti-VNN antibodies of grouper. The results of the challenge test for vaccinated fish using VNN virus titer 103.5 FID50/0.2 mL showed 60% of survival rate. Thus, the pmBA-CP DNA vaccine could be useful for increasing grouper immunity, and support production of grouper.

Preliminary study of mechanisms of intestinal inflammation induced by plant proteins in juvenile hybrid groupers (♀Epinephelus fuscoguttatus×♂E. lanceolatu)

Fish fed a high plant protein diet exhibit intestinal inflammation, the mechanism of which needs to be clarified. We preliminarily elucidate the mechanism of the TLRs/MyD88-PI3K/Akt signalling pathway in intestinal inflammation induced by plant proteins. The diets contained 60% fish meal (FM, controls), or had 45% of the fish meal protein replaced by soybean meal (SBM), peanut meal (PM), cottonseed meal (CSM) or cottonseed protein concentrate (CPC). After an 8-week feeding trial, fish were challenged by injection of Vibrio parahaemolyticus bacteria for 7 days until the fish stabilized. The results showed that the specific growth rate (SGR) of the FM group was higher than other groups. The SGR of the CPC group was higher than those of the SBM, PM and CSM groups. The catalase (CAT) contents in the serum of fish fed a plant protein diet were higher than in FM fish. The abundances of Rhodobacteraceae and Microbacteriaceae in the MI (mid intestine) were higher in the CPC group. The TLR-2 expressions in the MI and DI of plant protein-fed fish were up-regulated. The expressions of IL-6 in the PI and MI, of hepcidin and TLR-3 in the MI, and of TLR-3 in the DI, were all lower than those of fish fed FM. In the PI, MI and DI, the protein expressions of P-PI3K/T-PI3K in the SBM and PM groups were higher than in the FM group. After the challenge, the cumulative mortalities in the FM and CPC groups were lower than those of the SBM, PM and CSM groups. These results suggested that plant protein diets reduced antioxidant capacity and glycolipid metabolism, hindered the development of the intestine and reduced intestinal flora diversity. TLR-3 is involved in the immune regulation of the PI in CPC group, MI and DI in SBM, PM, CSM and CPC groups, while might be involved in the immune regulation of the PI in SBM, PM and CSM groups. Furthermore, PI3K/Akt signaling does not participate in the regulation of PI and MI in the CSM group, MI and DI in the CPC group.

Effects of dietary n-3 highly unsaturated fatty acids levels on growth, lipid metabolism and innate immunity in juvenile golden pompano (Trachinotus ovatus)

To investigate the effects of dietary n-3 highly unsaturated fatty acids (HUFA) levels on growth, lipid metabolism and innate immunity in juvenile golden pompano Trachinotus ovatus, a marine carnivorous teleost, a total of 450 fish (average body weight: 14.84 g) were randomly distributed into 18 cages at sea, each dietary group with three cages and respectively fed six diets (D1-D6) with 2.30% (D1), 0.64% (D2), 1.00% (D3), 1.24% (D4), 1.73% (D5), or 2.10% (D6) n-3 HUFA. Here, D1 with fish oil as lipid source was set as control, while D2-D6 used a mixed vegetable oil as lipid source and supplemented with docosahexaenoic acid- (DHA) and eicosapentaenoic acid- (EPA) enriched oils to adjust the n-3 HUFA levels. After 8 weeks feeding, the daily growth coefficient (DGC), specific growth rate (SGR) and feed efficiency ratio (FER) showed no significant difference among the six dietary groups (P > 0.05). The levels of EPA and DHA in serum and liver increased with the dietary n-3 HUFA levels. The activity of total superoxide disumutase (T-SOD) in serum of fish fed D4 and D5 were significantly higher than that of the other groups, whereas the opposite was true for serum IL-1β and IL-6 levels as well as liver malondialdehyde (MDA) content. The mRNA levels of genes related to hepatic lipid metabolism including sterol regulatory element-binding protein-1 (srebp-1), fatty acid binding protein 1 (fabp1), peroxisome proliferators-activated receptor alpha (pparα), elongase of very long-chain fatty acids 5 (elovl5) and fatty acyl desaturase 2 (fads2) were down-regulated in fish fed the diets with high n-3 HUFA levels, while those of apolipoprotein b 100 (aprob 100) and carnitine palmitoyl transferase 1 (cpt1) increased significantly as increasing n-3 HUFA levels up to 1.73% (D2-D5), but decreased in the 2.10% n-3 HUFA group (D6). In addition, the expression levels of genes related to innate immunity including interleukin-10 (il-10) and transforming growth factor β1 (tgf-β1) increased significantly when dietary n-3 HUFA increased from 0.64% to 1.73%, whereas the opposite was true for the expression levels of nuclear factor kappa-B (nf-κb), interleukin-1β (il-1β), interleukin-6 (il-6) and interleukin-8 (il-8). Overall, the results indicated that dietary n-3 HUFA at 1.24–1.73% (D4-D5) can effectively improve fatty acid profiles, lipid metabolism, antioxidant capacity and immune response of golden pompano.

Toxicity of Crude Fruit Endocarp Extract of Calabash (Lagenaria siceraria) on African Catfish (Clarias gariepinus) Juveniles

Background: Illicit disposal of scraped out endocarp of bottle gourds as part of processing activity for domestic use into the aquatic environment pose a big threat to the aquatic ecosystem. This study investigated the toxicity effects of crude fruit endocarp extracts of L. siceraria on C. gariepinus juveniles.&#x0D; Methodology: 120 mixed sex of C. gariepinus juveniles of mean weight and length (19.59 ±0.42 g; 14.6 ±0.80 cm) respectively were investigated. The fish were divided into 6 groups of 10 fish in each aquarium containing 5, 20, 35, 50 and 65 mg/L concentration of aqueous extract of L. siceraria and 0.00 mg/L (control) respectively with replicates for Four (4) days for acute toxicity analysis. The animals were sacrificed and blood samples collected for biochemical and isolation of the gills and liver for histopathological studies.&#x0D; Results: Experimental media pH, free carbon (iv) oxide, total alkalinity contents increased while dissolved oxygen decreased significantly (P&lt;0.05) with increase in concentration in the acute bioassay. Temperature did not differ significantly (P&gt;0.05) in all the groups thus, did not affect fish survival. Furthermore, AST, ALT and LDH profiles in blood serum of fish exposed to acute concentrations exhibited a significant increase (P&lt;0.05) with increase in concentration. The exposed gills revealed progressive striking histological alterations viz. thickening and shortening of secondary lamellae, degeneration of connective tissue and complete loss of secondary lamella while the liver showed progressive histo-architectural distortions such as hepatic hypertrophy, cellular degeneration (necrosis), haemorrhage and intracellular infiltration with increase in concentration of the L. siceraria extract.&#x0D; Conclusion: Aqueous extract of L. siceraria had adverse effect on juveniles of C. gariepinus, as evident in the negative modification of the body physiology via biochemical and histological investigations, thus toxic to the aquatic life. Further investigations on other vital organs - kidney, heart, GIT and the reproductive organs are recommended.

Combined effects of surface area of periphyton substrates and stocking density on growth performance, health status, and immune response of Nile tilapia (Oreochromis niloticus) produced in cages

A 4-month feeding trial was conducted to investigate the effect of surface area of periphyton substrates (PS) and stocking density (SD) of juvenile Nile tilapia, Oreochromis niloticus, on growth, major blood constituents, and some immunity biomarkers. Six treatments (T1–T6) were established in 18 floating cages (1 m3 water each) fixed in an earthen pond for growing tilapia (1.12 ± 0.10 g), in a 2 × 3 factorial design experiment (2 SD × 3 PS). For T1, T2, and T3, fish were stocked at a rate of 70 m−3 with 1, 2, or 3 PS units (area: 0.7, 1.4, and 2.0 m2, respectively). For T4–T6, fish were stocked at 90 m−3, also with 1, 2, or 3 PS units. All fish were fed a 20% crude protein supplemental diet. The best growth rates, feed efficiency, body composition, immune response, and overall health status were attained for T2 group with 70 fish m−3 in the presence of 2 PS units (1.4 m2) followed by T5 with 90 fish m−3 plus 2 PS. Stocking density affected albumin while periphyton substrates impacted cholesterol, triglycerides, and alanine aminotransferase levels in fish serum. Meanwhile, total proteins and glucose-6-phosphate dehydrogenase were not significantly affected. Serum immunoglobulin (IgM and IgG) values were relatively higher in fish reared at 70 m−3 than at 90 fish m−3 indicating better immunity response. Periphyton biomass (dry matter, DM and ash-free DM) was lower in T2, than in other treatments, whereas periphyton populations belonged mainly to Chlorophyta (52–75%), Cyanobacteria (17–23%), and Charophyta (4–21%). Accordingly, the present study suggests that 70 fish m−3 and 2 PS units (surface area of 1.4 m2) would be an optimal combination for the best growth, health status, and immunity response of juvenile Nile tilapia reared in periphyton-based cage system.

Comprehensive assessment of benthic diatom ( Amphora coffeaeformis ) as a feed additive in Nile tilapia ( Oreochromis niloticus ) diet

Four hundred and fifty Nile tilapia (Oreochromis niloticus), each weighing ca. 4 g, were randomly allocated into five equal groups in triplicate. The first group acts as control (A0). A1, A2, A3 and A4 groups were fed on rations supplemented with diatom, Amphora coffeaeformis, at 2.5, 5.0, 7.5 and 10%, respectively, for 63 days. Assessment of fish growth, biochemical composition, erythrocyte alterations, gonadal maturation, serum biomarkers, and liver and intestinal pathogens was carried out to identify fish welfare. Fish were challenged by Aeromonas hydrophila injection for an additional 14 days; then, mortality rate and some blood parameters were monitored. Results demonstrated that Amphora sp. insignificantly impacted fish growth, but it induced significant depletion in lipid content. Blood smear investigation indicated erythrocyte alterations in A4 group compared with A0 group. Male gonadosomatic index and relative fecundity demonstrated an increment in A3 and A4 groups respectively. A boost in fish immunity of A3 group was demonstrated through serum biomarkers and pathogenic bacterial identification in liver and intestine compared with other groups. Cumulative mortality of stressed fish was 90% in the A0 group and decreased to 30% in the A3 group. Blood analysis of stressed fish indicated higher tolerance in the A3 group. In conclusion, Amphora sp. can be used as an immunostimulant for increasing disease resistance under stress conditions.

Hamp Type-1 Promotes Antimicrobial Defense via Direct Microbial Killing and Regulating Iron Metabolism in Grass Carp (Ctenopharyngodon idella).

Hepcidin is an antimicrobial peptide and regulator of iron homeostasis which has two isoforms in most fishes and some mammals. Previous studies have reported that the two hepcidin isoforms have different roles. Hamp type-1 plays a regulatory role in iron metabolism and hamp type-2 mostly performs an antimicrobial role. In this study, we found that Ctenopharyngodon idella (C. idella) have only one hepcidin isoform (hamp type-1), which showed both broad-spectrum antibacterial and iron regulatory functions. C. idella hepcidin mature peptide (hepcidin-25) and truncated peptide (hepcidin-20) exhibited bactericidal activities against both Gram-positive and Gram-negative bacteria in a dose-dependent manner in part through membrane rupture and binding to bacterial genomic DNA. The data from challenge tests demonstrated that the administration of hepcidin-25 significantly reduced mortality rates of C. idella by A. hydrophila infection, probably due to direct bactericidal activities of the peptide and a reduction of iron content in the fish serum. In addition, a comparison between hepcidin-20 and -25 suggests that the N terminal 5 amino acids play a critical role in reducing iron content in fish serum. Our findings revealed an important role of hamp type-1 in maintaining iron homeostasis and fighting against bacterial infections, suggesting the hepcidin has implications for the prevention and control of bacterial infection in aquaculture.

Plasma metabolomic profiles associated with infant food allergy with further consideration of other early life factors

BackgroundFatty acids have been implicated in early life immune development. Food allergy provides a clear phenotype of early allergic disease. Fish oil and vitamin D have immune-modulating properties. We aimed to identify the metabolomic profile of (i) infant food allergy and (ii) factors linked to food allergy in past studies such as fish oil supplementation and serum 25OHD3 levels in early life. MethodsNMR was used to quantify 73 metabolites in plasma of 1 year old infants from the Barwon Infant Study (n=485). Logistic regression models were used to examine associations between infant metabolome and food allergy in infants. Linear regression models were used to describe associations between maternal fish oil supplementation and 25OHD3 levels with infant metabolites. ResultsA higher linoleic acid: total fatty acid (FA) ratio and phenylalanine level were associated with higher odds of food allergy. Antenatal fish oil supplementation was positively associated with docosahexaenoic acid (DHA) and omega-3 related metabolite levels. Postnatal 25OHD3 levels at 1 year of age were positively associated with several FA measures and creatinine and inversely with the saturated FA: total FA ratio. Only the postnatal 25OHD3 patterns persisted after adjustment for multiple comparisons. ConclusionsInfants with food allergy had altered fatty acid profiles at one year. Fish oil supplementation in pregnancy was associated with higher DHA and omega-3 related metabolites at 1 year of age. Associations were modest and the most robustly altered metabolomic profiles were with postnatal 25OHD3 levels.

Hepato-nephrotoxicity in late juvenile of Oreochromis niloticus exposed to gibberellic acid: Ameliorative effect of Spirulina platensis

The current work intended to inspect the hepato-nephrotoxicity of gibberellic acid (GA3) in juvenile of Oreochromis niloticus as well as the possibility of restoration after dietary addition of different concentrations of Spirulina platensis (SP). Fishes were evenly assorted into five groups: Group I assigned as control, Group II fed on basal diet and exposed to 150 mg/L gibberellic acid (GA3). The 3rd, 4th, and 5th groups exposed to150 mg/L gibberellic acid (GA3) and previously fed for two months on SP supplemented diets at levels of 5, 20, and 100 g/kg, respectively. Fish serum were utilized to check glucose, total protein, hepatic and renal functions, enzymatic and non-enzymatic antioxidants activities (superoxide dismautase; SOD, catalase; CAT, and total antioxidant capacity; TAC) as well as histopathological alterations in liver and kidney. The results showed that creatinine, uric acid, liver enzymes, glucose, total protein, SOD, and CAT were significantly elevated in GA3-treated group. Liver of GA3-treated fish manifested some histopathological changes (hypertrophy, cytoplasmic vacuolization, and apoptotic cells with pyknotic nuclei, necrosis, dilated blood sinusoids, and lymphocytic aggregation around the central veins). Kidney of GA3-exposed fish revealed edema of the epithelium lining of some renal tubules and some showed vacuolar degeneration and dissociation. Hypertrophy in the glomerulus was observed with dilated blood capillaries. SP supplementation restored these biochemical, antioxidants, and histological changes near to control levels. This improvement was higher with 100 g/kg SP showing concentration dependency. According to this study we can conclude that SP supplementation can improve the hepato- and nephrotoxicity caused by GA3 exposure indicating its role as potent antioxidant food additive.

Dual-emissive carbon dots for dual-channel ratiometric fluorometric determination of pH and mercury ion and intracellular imaging.

Dual-emissive carbon dots (CDs) were fabricated for dual-channel ratiometric fluorometric determination of pH and mercury ion (Hg2+) and intracellular imaging. Dual-emissive CDs were synthesized by one-pot solvothermal treatment of cabbage. The CDs exhibited two distinctive fluorescence emissions at 500 and 678nm under single excitation at 410nm. The green emission (500nm) had reversible linear response to pH (7.0-12.0) due to deprotonation and protonation of surface functional groups and their non-covalent interactions. On the other hand, the red emission (678nm) had efficient and selective fluorescence response to Hg2+ by formation of non-emission complex between CDs and Hg2+. The limit of detection (LOD) and limit of quantification (LOQ) for Hg2+ were 6.25 and 20.63nM, respectively. The CDs have been successfully applied for label-free ratiometric fluorometric determination of pH and Hg2+ in fish and human serum samples with good recoveries (92.0-108.3%). In addition, the CDs had excellent photostability, low cytotoxicity, and good biocompatibility for intracellular imaging. All in all, the system was multi-functional in determination, high in sensitivity, and excellent in selectivity, which demonstrated wide and promising applicability for biosensing and bioimaging in the future. Graphical abstract Schematic presentation of dual-emission carbon dots (CDs) synthesized by solvothermal treatment of cabbage for dual-channel determination of pH and Hg2+.

Phenotype, Virulence and Immunogenicity of Edwardsiella piscicida Cyclic AMP Receptor Protein (Crp) Mutants in Catfish Host.

Edwardsiella piscicida, a facultative aerobic pathogen belonging to the Enterobacteriaceae family, is the etiological agent of edwardsiellosis that causes significant economic loses in the aquaculture industry. cAMP receptor protein (CRP) is one of the most important transcriptional regulators, which can regulate large quantities of operons in different bacteria. Here we characterize the crp gene and report the effect of a crp deletion in E. piscicida. The crp-deficient mutant lost the capacity to utilize maltose, and showed significantly reduced motility due to the lack of flagella synthesis. We further constructed a ΔPcrp mutant to support that the phenotype above was caused by the crp deletion. Evidence obtained in fish serum killing assay and competitive infection assay strongly indicated that the inactivation of crp impaired the ability of E. piscicida to evade host immune clearance. More importantly, the virulence of the crp mutant was attenuated in both zebrafish and channel catfish, with reductions in mortality rates. In the end, we found that crp mutant could confer immune protection against E. piscicida infection to zebrafish and channel catfish, indicating its potential as a live attenuated vaccine.

Improvement of non-specific immunity, growth, and activity of digestive enzymes in Carassius auratus as a result of apple cider vinegar administration to diet.

This study was conducted to evaluate the effects of apple cider vinegar (ACV) administration on non-specific immunity of serum and skin mucus, growth indices, and activity of digestive enzymes (amylase, lipase, and protease) in Carassius auratus. For this purpose, 180 fish (weighing 7.35 ± 0.19g) were allocated to 4 treatment groups with 3 replications in a completely randomized design. Fish were fed for 105days using a basal diet supplemented with 0% (control), 1% (T 1), 2% (T 2), and 4% (T 3) ACV (contained 5% acetic acid). Results showed a significant increase in lysozyme activity, ACH50, and total immunoglobulin of skin mucus in fish fed with T2 diet (p < 0.05). Total immunoglobulin and lysozyme activity were significantly lower in the serum of fish fed with control diet than those fed with the mentioned treatment (p < 0.05). The highest value was observed in fish fed with T2 diet. Minimum (p < 0.05) complement activity (1.52 ± 0. 25Uml-1) was observed in fish fed with control diet. The mean of the final weights (17.35 ± 1.39g), daily growth (1.0 ± 0.01g), and specific growth rate (2.19 ± 0.14) was significantly higher in T3 diet group than the controls (p < 0.05). While the highest amylase-specific activity was observed in the controls (p < 0.05), there was a significant increase in specific activity of protease, lipase, and alkaline phosphatase in T2 diet group (p < 0.05). According to the results of this study, the inclusion of a limited quantity of ACV (4%) into the diet can improve immunity and growth parameters in C. auratus.

Isolation, identification and pathogenicity of Proteus vulgaris from moribund common carp (Cyprinus carpio) farmed in China

Common carp (Cyprinus carpio) is one of the most important aquaculture species in the world. In recent years, several outbreaks of unknown etiology has caused huge economic losses in common carp culture. To determine the death cause of common carp in Chongqing, China, we isolated potential pathogens from the infected common carp. The isolated bacteria (CQC01) recovered from moribund common carp was identified as Proteus vulgaris based on biochemical characterization and 16S rDNA sequence analysis. The pathogenicity of CQC01 was determined by artificial infection. Common carp experimentally infected with CQC01 showed the same symptoms as the naturally infected fish, including swelling on the anus, congestion on the eyelids, fins and abdominal muscle. At 6 h post infection (hpi), malondialdehyde (MDA), catalase (CAT), alanine aminotransferase (ALT), alkaline phosphatase (AKP), and lysozyme (LYZ) level in serum of fish infected with high concentration of CQC01 (109 CFU/mL) were significantly increased, but superoxide dismutase (SOD) activity was significantly decreased; whereas, liver tissue of infected fish showed immunological and oxidative stress. The histopathology of the challenged fish showed pathological lesions on hepatopancreas, kidney, spleen and muscle, suggesting CQC01 infection caused great damage to fish. Antimicrobial susceptibility test showed that the strain CQC01 was not resistant to most of antibiotics. Narrow-spectrum antibiotics were recommended for the control of strain CQC01. This study highlights the incrimination of P. vulgaris in the disease outbreak of cultured common carp for the first time. These findings provide guidance for the prevention and control of Proteus related diseases.