Oxidative stress induced by hydrogen peroxide disrupts zebrafish visual development by altering apoptosis, antioxidant and estrogen related genes.

Hydrogen peroxide is considered deleterious molecule that cause cellular damage integrity and function. Its key redox signaling molecule in oxidative stress and exerts toxicity on a wide range of organisms. Thus, to understand whether oxidative stress alters visual development, zebrafish embryos were exposed to H2O2 at concentration of 0.02 to 62.5 mM for 7 days. Eye to body length ratio (EBR) and apoptosis in retina at 48 hpf, and optomotor response (OMR) at 7 dpf were all measured. To investigate whether hydrogen peroxide-induced effects were mediated by oxidative stress, embryos were co-incubated with the antioxidant, glutathione (GSH) at 50 µM. Results revealed that concentrations of H2O2 at or above 0.1 mM induced developmental toxicity, leading to increased mortality and hatching delay. Furthermore, exposure to 0.1 mM H2O2 decreased EBR at 48 hpf and impaired OMR visual behavior at 7 dpf. Additionally, exposure increased the area of apoptotic cells in the retina at 48 hpf. The addition of GSH reversed the effects of H2O2, suggesting the involvement of oxidative stress. H2O2 decreased the expression of eye development-related genes, pax6α and pax6ß. The expression of apoptosis-related genes, tp53, casp3 and bax, significantly increased, while bcl2α expression decreased. Antioxidant-related genes sod1, cat and gpx1a showed decreased expression. Expression levels of estrogen receptors (ERs) (esr1, esr2α, and esr2ß) and ovarian and brain aromatase genes (cyp19a1a and cyp19a1b, respectively) were also significantly reduced. Interestingly, co-incubation of GSH effectivity reversed the impact of H2O2 on most parameters. Overall, these results demonstrate that H2O2 induces adverse effects on visual development via oxidative stress, which leads to alter apoptosis, diminished antioxidant defenses and reduced estrogen production.

Antiangiogenic potential of Lepista nuda extract suppressing MAPK/p38 signaling-mediated developmental angiogenesis in zebrafish and HUVECs.

The medicinal properties of natural/edible plant products and their use are popular in traditional practice owing to their nutritional contents with little to no side effects. Lepista nuda (L. nuda), an edible mushroom (Clitocybe nuda, commonly known as blewit), has attracted researchers to evaluate its contents and the mechanism of its activities. In the current study, we focused on evaluating the antiangiogenic effects of L. nuda water extract on zebrafish development and in vitro human umbilical vein endothelial cell (HUVEC) tube formation. Bioactive components such as ergothioneine, eritadenine, and adenosine were identified and quantified by HPLC analysis. The L. nuda extract showed antiangiogenic properties and inhibited intersegmental vessel (ISV), caudal vein plexus (CVP), hyaloid vessel (HV), and subintestinal vessel (SIV) development in Tg (fli1: EGFP) zebrafish embryos. The expression of angiogenesis-related genes (vegfaa, kdrl, vegfba, flt1, kdr) was affected following L. nuda extract treatment. L. nuda extract attenuated in vitro HUVEC tube formation, migration, and invasion. Furthermore, inhibition of MAPK/p38 signaling and depletion of proangiogenic genes, including growth factors (fgf, ang2, and vegfa); primary and accessory receptors (tie2, vegfr2, and eng); MMPs (mmp1 and mmp2); and cytokines (il-1α, il-1ß, il-6, and tnf-α) was observed in HUVECs following L. nuda treatment. An in vivo zebrafish xenograft assay showed that L. nuda extract inhibited HuCCT1 cell-induced SIV sprouting in HuCCT1-injected embryos. Collectively, the results suggest that L. nuda could be a potential inhibitor of angiogenesis limiting cancer progression.

Improvement in the probiotic efficacy of Bacillus subtilis E20-stimulates growth and health status of white shrimp, Litopenaeus vannamei via encapsulation in alginate and coated with chitosan.

The aim of this study was to increase the efficacy of probiotic Bacillus subtilis E20 by encapsulating the probiotic in alginate and coating it with chitosan. The protective effect was evaluated by firstly ensuring the viability of encapsulated probiotics in simulated gastrointestinal fluid (SGF) and simulated intestinal fluid (SIF) conditions and then at different storage temperatures. In addition, the encapsulated probiotic was incorporated into the diet to improve the growth performance and health status of white shrimp, Litopenaeus vannamei. B. subtilis E20 has the ability to survive in SGF when encapsulated in 1.5-2% alginate and coated with 0.4% chitosan. Furthermore, viability increased significantly in SIF compared to the probiotic encapsulated in 1% alginate and coated with 0.4% chitosan and the non-encapsulated probiotic. Longer storage time and adverse conditions affected probiotics' survival, which was improved by the encapsulation with significantly higher viability than the non-encapsulated probiotic at different temperatures and storage duration. Encapsulation of B. subtilis E20 and dietary administration at 107 CFU kg-1 decreased shrimp mortality after a Vibrio infection, thereby improving shrimp's disease resistance, while the non-encapsulated probiotic required 109 CFU kg-1 to achieve better resistance. Although the best results of growth performance, immune response, and disease resistance against Vibrio alginolyticus were found in the shrimp fed with the diets supplemented with encapsulated probiotic at >108 CFU kg-1, shrimp's growth performance and health status improved after being fed 107 CFU kg-1 encapsulated probiotic for 56 days. Together, the results of this study prove that encapsulation could improve the viability of probiotic in different gastrointestinal conditions and adverse storage temperatures. Overall, lower concentrations of encapsulated probiotic B. subtilis E20 (107 CFU kg-1) was able to increase the growth performance and health status of shrimp.

A synbiotic containing prebiotic prepared from a by-product of king oyster mushroom, Pleurotus eryngii and probiotic, Lactobacillus plantarum incorporated in diet to improve the growth performance and health status of white shrimp, Litopenaeus vannamei.

This study aimed to evaluate the effects of a synbiotic composite an extract from a by-product of king oyster mushroom, Pleurotus eryngii (KOME), and probiotic Lactobacillus plantarum 7-40 on the growth performance and health status of white shrimp, Litopenaeus vannamei. The KOME was able to stimulate the growth of probiotic, but not the growth of Vibrio pathogens, including V. alginolyticus, V. parahaemolyticus, and V. harveyi. Four diets were formulated, including a control diet supplemented without prebiotic and probiotic, a basal diet supplemented with KOME (5 g kg-1) (ME), a basal diet supplemented with probiotic (1 × 108 CFU kg-1) (LP), and a basal diet supplemented with KOME (5 g kg-1) and probiotic (1 × 108 CFU kg-1) (SYN). Shrimp fed the ME, LP, and SYN diets had significantly higher survival than that of shrimp fed with the control diet for 8 weeks. Shrimp in the SYN group also had a significantly higher weight gain and total final weight in comparison with the control and other treatments. In the intestinal tract, lactic acid bacteria count was significantly higher in the SYN group, whereas the Vibrio-like bacteria count was significantly higher in the ME group than in the control group. For the health status assessment, the disease resistance of shrimp against V. alginolyticus was improved in all treatments compared to the shrimp in control. Shrimps in the SYN group had significantly lower cumulative mortality due to the significant increase in immune responses, including phenoloxidase, respiratory burst, and lysozyme activity, and the gene expression of pexn and pen4 in the haemocytes, and lgbp, sp, propoii, pexn, pen3a, pen4, and gpx in the haepatopancreas of shrimp as compared to the control. Therefore, it is suggested that a combination of KOME and probiotics can be used as a synbiotic to improve the growth performance and reduce the risk of infectious diseases caused by Vibrio and at the same time significantly contribute to the circular economy.

Probiotic Bacillus safensis NPUST1 Administration Improves Growth Performance, Gut Microbiota, and Innate Immunity against Streptococcus iniae in Nile tilapia (Oreochromis niloticus).

Probiotics are considered ecofriendly alternatives to antibiotics as immunostimulants against pathogen infections in aquaculture. In the present study, protease-, amylase-, cellulase-, and xylanase-producing Bacillus safensis NPUST1 were isolated from the gut of Nile tilapia, and the beneficial effects of B. safensis NPUST1 on growth, innate immunity, disease resistance and gut microbiota in Nile tilapia were evaluated by feeding tilapia a basal diet or basal diet containing 105 and 106-107 CFU/g for 8 weeks. The results showed that the weight gain, feed efficiency and specific growth rate were significantly increased in tilapia fed a diet containing 106 CFU/g and 107 CFU/g B. safensis NPUST1. Intestinal digestive enzymes, including protease, amylase and lipase, and hepatic mRNA expression of glucose metabolism and growth-related genes, such as GK, G6Pase, GHR and IGF-1, were also significantly increased in the 106 CFU/g and 107 CFU/g B. safensis NPUST1 treated groups. Immune parameters such as phagocytic activity, respiratory burst and superoxide dismutase activity in head kidney leukocytes, serum lysozyme, and the mRNA expression of IL-1ß, IL-8, TNF-α and lysozyme genes were significantly induced in the head kidney and spleen of 106 CFU/g and 107 CFU/g B. safensis NPUST1 treated fish. The cumulative survival rate was significantly increased in fish fed a diet containing 106 CFU/g and 107 CFU/g B. safensis NPUST1 after challenge with Streptococcus iniae. Dietary supplementation with B. safensis NPUST1 improves the gut microbiota of Nile tilapia, which increases the abundance of potential probiotics and reduces the abundance of pathogenic pathogens. The present study is the first to report the use of B. safensis as a potential probiotic in aquaculture, and a diet containing 106 CFU/g B. safensis NPUST1 is adequate for providing beneficial effects on growth performance and health status in tilapia.

Effect of Tempeh on Gut Microbiota and Anti-Stress Activity in Zebrafish.

Rhizopus oryzae is a fungus used to ferment tempeh in Indonesia and is generally recognized as safe (GRAS) for human consumption by the USA FDA. We previously assessed the effect of a tempeh extract on cortisol levels in zebrafish but did not include behavioral studies. Here, we measured the GABA content in three strains of Rhizopus oryzae, two isolated by us (MHU 001 and MHU 002) and one purchased. We then investigated the effect of tempeh on cortisol and the gut microbiota in a zebrafish experimental model. GABA concentration was the highest in MHU 002 (9.712 ± 0.404 g kg-1) followed by our MHU 001 strain and the purchased one. The fish were divided into one control group fed a normal diet and three experimental groups fed soybean tempeh fermented with one of the three strains of Rhizopus oryzae. After two weeks, individual fish were subjected to unpredicted chronic stress using the novel tank diving test and the tank light-dark test. Next-generation sequencing was used to analyze gut microbial communities and RT-PCR to analyze the expression of BDNF (brain-derived neurotrophic factor) gene and of other genes involved in serotonin signaling/metabolism in gut and brain. Tempeh-fed zebrafish exhibited increased exploratory behavior (less stress) in both tank tests. They also had significantly reduced gut Proteobacteria (include E. coli) (51.90% vs. 84.97%) and significantly increased gut Actinobacteria (include Bifidobacterium spp.) (1.80% vs. 0.79%). The content of Bifidobacteriumadolescentis, a "psychobiotic", increased ten-fold from 0.04% to 0.45%. Tempeh also increases BDNF levels in zebrafish brain. Rhizopus oryzae MHU 001 greatly improved the anti-stress effect of tempeh and microbiota composition in zebrafish gut.

A potential probiotic Chromobacterium aquaticum with bacteriocin-like activity enhances the expression of indicator genes associated with nutrient metabolism, growth performance and innate immunity against pathogen infections in zebrafish (Danio rerio).

The use of probiotics as alternatives to antibiotics for disease control is a relatively eco-friendly approach in aquaculture; hence, studies isolating and assessing the benefit of potential probiotics to fish farming are common. The zebrafish is an excellent model system for validating beneficial functions of potential probiotics before their practical application in aquaculture. Here, a potentially probiotic Chromobacterium aquaticum was isolated from lake water samples and characterized by biochemical analysis and 16S rDNA sequencing. The probiotic produced extracellular enzymes (protease and xylanase) and a bacteriocin-like substance, which exhibited tolerance to extreme pH and high-temperature conditions and broad-spectrum bactericidal activity against diverse pathogens, including aquatic, foodborne, clinical and plant pathogens. The effects of C. aquaticum on zebrafish nutrient metabolism, growth performance and innate immunity were evaluated by measuring the expression of indicator genes after C. aquaticum feeding for 8 weeks. Fish administered the probiotic exhibited significantly increased hepatic mRNA expression of carbohydrate metabolism-related genes, including glucokinase (GK), hexokinase (HK), glucose-6-phosphatase (G6Pase), and pyruvate kinase (PK-L), and growth-related genes, including the growth hormone receptor (GHR) and insulin-like growth factor-1 (IGF-1). Innate immune-related genes (IL-1ß, IL-6, TNF-α, IL-10, IL-21, NF-κb, lysozyme and complement C3b) were induced in fish with probiotic supplementation. Probiotic-treated fish exhibited a higher survival rate than control fish after challenge with Aeromonas hydrophila and Streptococcus iniae. Together, these data suggest that C. aquaticum, as a probiotic feed supplement, could enhance nutrient metabolism and growth performance and could modulate innate immunity against A. hydrophila and S. iniae in zebrafish.

Molecular Characterization and Heterologous Production of the Bacteriocin Peocin, a DNA Starvation/Stationary Phase Protection Protein, from Paenibacillus ehimensis NPUST1.

The production of a bacteriocin-like substance with antimicrobial activity, named peocin, by the probiotic Paenibacillus ehimensis NPUST1 was previously reported by our laboratory. The present study aimed to identify peocin and increase the peocin yield by heterologous expression in Escherichia coli BL21(DE3). Peocin was identified as a DNA starvation/stationary phase protection protein, also called DNA-binding protein from starved cells (Dps), by gel overlay and LC-MS/MS analysis. For mass production of peocin, fed-batch cultivation of E. coli was performed using a pH-stat control system. Purification by simple nickel affinity chromatography and dialysis yielded 45.3 mg of purified peocin from a 20-mL fed-batch culture (49.3% recovery). The biological activity of the purified peocin was confirmed by determination of the MIC and MBC against diverse pathogens. Purified peocin exhibited antimicrobial activity against aquatic, food spoilage, clinical and antibiotic-resistant pathogens. In an in vivo challenge test, zebrafish treated with purified peocin exhibited significantly increased survival rates after A. hydrophila challenge. The present study is the first to show the antimicrobial activity of Dps and provides an efficient strategy for production of bioactive peocin, which will aid the development of peocin as a novel antimicrobial agent with potential applications in diverse industries.

Improvements in the growth performance, immunity, disease resistance, and gut microbiota by the probiotic Rummeliibacillus stabekisii in Nile tilapia (Oreochromis niloticus).

The application of probiotics as an eco-friendly alternative to antibiotics is an emerging strategy for sustainable aquaculture. In the present study, Rummeliibacillus stabekisii was isolated from the gut of Nile tilapia, and the effects of R. stabekisii on the growth, innate immunity, disease resistance, and gut microbiota of Nile tilapia (Oreochromis niloticus) were investigated. The results showed significantly increased weight gain (WG), feed conversion ratio (FCR), and feed efficiency (FE) in Nile tilapia fed R. stabekisii for 8 weeks compared to those in fish fed a control diet. Intestinal digestive enzymes such as protease, cellulase, and xylanase were also significantly increased in the R. stabekisii-administered groups. Enhanced cumulative survival was exhibited in fish fed R. stabekisii after challenge with Aeromonas hydrophila and Streptococcus iniae. Immune parameters such as the phagocytic activity, respiratory bursts, and superoxide dismutase of head kidney leukocytes; serum lysozyme activity; and expression of the cytokine genes interleukin-1ß, tumor necrosis factor-α, transforming growth factor-ß, and heat shock protein 70 were significantly elevated in fish fed R. stabekisii. Administration of R. stabekisii considerably increased the abundance of potential probiotics (Bacillus and Lactobacillus spp.) and reduced abundances of potential pathogenic bacteria (Streptococcus and Staphylococcus spp.) in fish intestines. The present study indicated that dietary supplementation with R. stabekisii improved the growth, immunity, disease resistance, and gut microflora of Nile tilapia. This research is the first study reporting that the genus Rummeliibacillus is a potential probiotic in animals, suggesting that R. stabekisii can be used as a feed additive to enhance the growth and health status in tilapia.

Multiple-strain probiotics appear to be more effective in improving the growth performance and health status of white shrimp, Litopenaeus vannamei, than single probiotic strains.

The probiotic efficiencies of the mixed probiotics containing Lactobacillus pentosus BD6, Lac. fermentum LW2, Bacillus subtilis E20, and Saccharomyces cerevisiae P13 for shrimp growth and health status improvement were better than those when using single probiotics. The probiotic mixture at a level of 108 colony-forming units (cfu) (kg diet)-1 and the diets containing BD6 and E20 at 109 cfu (kg diet)-1 significantly improved the growth and health status of shrimp, whereas the diets containing P13 or LW2 did not significantly affect the growth of shrimp. No significant difference in the carcass composition was recorded among the control and treatments. After 56 days of feeding, shrimp fed the diet containing the probiotic mixture (107∼109 cfu (kg diet)-1) had higher survival after injection with the V. alginolyticus, but 109 cfu (kg diet)-1 of single probiotics (except for S. cerevisiae P13) had to be administered to improve shrimp survival. The better disease resistance of shrimp in groups fed the probiotic mixture might have been due to increased phenoloxidase activity, respiratory bursts, and lysozyme activity of hemocytes. Therefore, we considered that the probiotic mixture could adequately provide probiotic efficiency for white shrimp, and a diet containing 108 cfu (kg diet)-1 probiotic mixture is recommended.

Dietary administration of Bacillus amyloliquefaciens R8 reduces hepatic oxidative stress and enhances nutrient metabolism and immunity against Aeromonas hydrophila and Streptococcus agalactiae in zebrafish (Danio rerio).

Zebrafish (Danio rerio) are an excellent model for assessing the beneficial effects of probiotics before applying them in aquaculture. This study evaluated the effects on zebrafish of dietary supplementation with the probiotic Bacillus amyloliquefaciens R8, which heterologously expresses xylanase from rumen fungi. Nutrient metabolism, hepatic oxidative stress, and innate immunity against pathogen infections were investigated. Treated zebrafish received feed supplemented with B. amyloliquefaciens R8 for 30 days and then were compared to zebrafish that were fed a control diet. The treated fish showed significant increases in xylanase activity in the intestines. The livers of the treated fish showed increased mRNA expressions of glycolysis-related genes of hexokinase, glucokinase, glucose-6-phosphatase, and pyruvate kinase; and higher enzyme activities of 3-hydroxyacyl-coenzyme A dehydrogenase and citrate synthase which are associated with fatty acid ß-oxidation and mitochondrial integrity. The livers of treated fish also showed decreased mRNA expressions of oxidative stress-related genes (SOD, Gpx, NOS2, and Hsp70) and an apoptotic gene (tp53), as well as increased expression of an anti-apoptotic gene (bcl-2). The probiotics-treated fish had increased expression of innate immune-related genes (IL-1ß, IL-6, IL-21, TNF-α, and TLR-1, -3, and -4). Following challenge with Aeromonas hydrophila and Streptococcus agalactiae, treated fish showed increased a higher survival rate than control fish. Overall, results showed that the administration of xylanase-expressing B. amyloliquefaciens R8 can potentially improve nutrient metabolism and hepatic stress tolerance, and enhance immunity and disease resistance against A. hydrophila and S. agalactiae in zebrafish.

Dietary administration of probiotic Paenibacillus ehimensis NPUST1 with bacteriocin-like activity improves growth performance and immunity against Aeromonas hydrophila and Streptococcus iniae in Nile tilapia (Oreochromis niloticus).

Bacteria-induced diseases are a major cause of mortality in aquaculture. Probiotics have commonly been used to replace antibiotics for prophylactic biocontrol in aquaculture. In the present study, Paenibacillus ehimensis NPUST1 was isolated from a tilapia culture pond. This probiotic has bacteriocin-like activities against Aeromonas hydrophila and was characterized by biochemical analysis and 16S rDNA sequencing. The physiochemical properties of a crude extract of the bacteriocin-like substance revealed low pH and high thermal tolerance. The substance exhibited broad-spectrum antimicrobial activity against diverse aquatic pathogens, food spoilage, clinical pathogens, and plant pathogens. The effect of dietary supplementation with P. ehimensis NPUST1 was evaluated in regard to the growth of Nile tilapia (Oreochromis niloticus) and immunity against pathogenic infection. The results showed significantly increased weight gain (WG), feed conversion ratio (FCR), and feed efficiency (FE) in Nile tilapia fed P. ehimensis NPUST1 for 2 months compared with fish fed a control diet. When challenged with A. hydrophila and S. iniae, the fish fed P. ehimensis NPUST1 also exhibited a higher survival rate than fish fed the control diet. The immune parameters revealed that the P. ehimensis NPUST1-fed fish had significantly higher phagocytic activity, respiratory burst, and superoxide dismutase (SOD) of the head kidney leukocytes, as well as higher serum lysozyme activity and expression of cytokines TNF-α and IL-1ß than the fish fed the control diet. These results indicate that dietary supplementation with P. ehimensis NPUST1 improved the growth performance, immunity, and disease resistance in Nile tilapia.

Dietary supplementation with xylanase-expressing B. amyloliquefaciens R8 improves growth performance and enhances immunity against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus).

Bacillus amyloliquefaciens has attracted attention as a probiotic in aquaculture due to its immunostimulatory activity against pathogenic infection. Xylanases are extensively used in animal feed to degrade plant ingredients, enhancing nutrient utilization and increasing the growth rate of various animals. In the present study, the effects of dietary supplementation with B. amyloliquefaciens and xylanase-expressing B. amyloliquefaciens R8 on the growth of Nile tilapia (Oreochromis niloticus) and immunity against Aeromonas hydrophila were evaluated. The results showed that the xylanase activity in the intestine, weight gain (WG), feed efficiency (FE) and condition factor (CF) of Nile tilapia fed B. amyloliquefaciens R8 for 2 months were significantly increased compared with those of the fish fed the control diet and B. amyloliquefaciens. Moreover, the mRNA expression of growth- and metabolism-related genes, such as insulin-like growth factor-1 (igf-1), glucokinase (GK), glucose-6-phosphate 1-dehydrogenase (G6PD), and glucose-6-phosphatase (G6Pase), was significantly induced in Nile tilapia fed administered B. amyloliquefaciens R8, and this group also exhibited a higher survival rate than the control fish following a challenge with A. hydrophila. The phagocytic activity and respiratory burst activity of head kidney leukocytes as well as the serum lysozyme activity of B. amyloliquefaciens R8-fed Nile tilapia were significantly higher than those of fish fed the control diet for 2 months. Superoxide dismutase (SOD) levels in the head kidney leukocytes of Nile tilapia fed B. amyloliquefaciens R8 differed from those of fish fed the control diet, but this was not significant. These results indicate that dietary supplementation with xylanase-expressing B. amyloliquefaciens R8 improves growth performance and enhances immunity and disease resistance against A. hydrophila in Nile tilapia.

Transgenic expression of omega-3 PUFA synthesis genes improves zebrafish survival during Vibrio vulnificus infection.

BACKGROUND: Highly desaturated n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are synthesized by desaturases and elongase. They exert hepatoprotective effects to prevent alcoholic fatty liver syndrome or cholestatic liver injury. However, it is unclear how n-3 PUFAs improve immune function in liver. Vibrio vulnificus, a gram-negative bacterial pathogen, causes high mortality of aquaculture fishes upon infection. Humans can become infected with V. vulnificus through open wounds or by eating raw seafood, and such infections may result in systemic septicemia. Moreover, patients with liver diseases are vulnerable to infection, and are more likely than healthy persons to present with liver inflammation following infection. This study quantified n-3 PUFAs and their anti-bacterial effects in Fadsd6 and Elvol5a transgenic zebrafish. RESULTS: Two transgenic zebrafish strains with strong liver specific expression of Fadsd6 and Elvol5a (driven by the zebrafish Fabp10 promoter) were established using the Tol2 system. Synthesis of n-3 PUFAs in these strains were increased by 2.5-fold as compared to wild type (Wt) fish. The survival rate in 24 h following challenge with V. vulnificus was 20 % in Wt, but 70 % in the transgenic strains. In addition, the bacteria counts in transgenic fish strains were significantly decreased. The expression levels of pro-inflammatory genes, such as TNF-α, IL-1ß, and NF-κB, were suppressed between 9 and 12 h after challenge. This study confirms the anti-bacterial function of n-3 PUFAs in a transgenic zebrafish model. CONCLUSIONS: Fadsd6 and Elvol5a transgenic zebrafish are more resistant to V. vulnificus infection, and enhance survival by diminishing the attendant inflammatory response.

Recombinant production of biologically active giant grouper (Epinephelus lanceolatus) growth hormone from inclusion bodies of Escherichia coli by fed-batch culture.

Growth hormone (GH) performs important roles in regulating somatic growth, reproduction, osmoregulation, metabolism and immunity in teleosts, and thus, it has attracted substantial attention in the field of aquaculture application. Herein, giant grouper GH (ggGH) cDNA was cloned into the pET28a vector and expressed in Shuffle® T7 Competent Escherichia coli. Recombinant N-terminal 6× His-tagged ggGH was produced mainly in insoluble inclusion bodies; the recombinant ggGH content reached 20% of total protein. For large-scale ggGH production, high-cell density E. coli culture was achieved via fed-batch culture with pH-stat. After 30h of cultivation, a cell concentration of 41.1g/l dry cell weight with over 95% plasmid stability was reached. Maximal ggGH production (4.0g/l; 22% total protein) was achieved via mid-log phase induction. Various centrifugal forces, buffer pHs and urea concentrations were optimized for isolation and solubilization of ggGH from inclusion bodies. Hydrophobic interactions and ionic interactions were the major forces in ggGH inclusion body formation. Complete ggGH inclusion body solubilization was obtained in PBS buffer at pH 12 containing 3M urea. Through a simple purification process including Ni-NTA affinity chromatography and refolding, 5.7mg of ggGH was obtained from 10ml of fed-batch culture (45% recovery). The sequence and secondary structure of the purified ggGH were confirmed by LC-MS/MS mass spectrometry and circular dichroism analysis. The cell proliferation-promoting activity was confirmed in HepG2, ZFL and GF-1 cells with the WST-1 colorimetric bioassay.

Molecular cloning and functional characterization of the hepcidin gene from the convict cichlid (Amatitlania nigrofasciata) and its expression pattern in response to lipopolysaccharide challenge.

The hepcidin gene is widely expressed in many fish species and functions as an antimicrobial peptide, suggesting that it plays an important role in the innate immune system of fish. In the present study, the Amatitlania nigrofasciata hepcidin gene (AN-hepc) was cloned from the liver and its expression during an immune response was characterized. The results of quantitative PCR and RT-PCR showed that the AN-hepc transcript was most abundant in the liver. The expression of AN-hepc mRNA was significantly increased in the liver, stomach, heart, intestine, gill and muscle but was not significantly altered in the spleen, kidney, brain or skin after lipopolysaccharide challenge. The synthetic AN-hepc peptide showed a wide spectrum of antimicrobial activity in vitro toward gram-positive and gram-negative bacteria. In particular, this peptide demonstrated potent antimicrobial activity against the aquatic pathogens Vibrio alginolyticus, V. parahaemolyticus, V. vulnificus, Aeromonas hydrophila and Streptococcus agalactiae. The in vivo bacterial challenge results demonstrated that the synthetic AN-hepc peptide significantly improved the survival rate of S. agalactiae- and V. vulnificus-infected zebrafish. Taken together, these data indicate an important role for AN-hepc in the innate immunity of A. nigrofasciata and suggest its potential application in aquaculture for increasing resistance to disease.

Liposome-encapsulated cinnamaldehyde enhances zebrafish (Danio rerio) immunity and survival when challenged with Vibrio vulnificus and Streptococcus agalactiae.

Cinnamaldehyde, which is extracted from cinnamon, is a natural compound with activity against bacteria and a modulatory immune function. However, the antibacterial activity and immunostimulation of cinnamaldehyde in fish has not been well investigated due to the compound's poor water solubility. Thus, liposome-encapsulated cinnamaldehyde (LEC) was used to evaluate the effects of cinnamaldehyde on in vitro antibacterial activity against aquatic pathogens and in vivo immunity and protection parameters against Vibrio vulnificus and Streptococcus agalactiae. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) as well as bactericidal agar plate assay results demonstrated the effective bacteriostatic and bactericidal potency of LEC against Aeromonas hydrophila, V. vulnificus, and S. agalactiae, as well as the antibiotic-resistant Vibrio parahaemolyticus and Vibrio alginolyticus. Bacteria challenge test results demonstrated that LEC significantly enhances the survival rate and inhibits bacterial growth in zebrafish infected with A. hydrophila, V. vulnificus, and S. agalactiae. A gene expression study using a real-time PCR showed that LEC immersion-treated zebrafish had increased endogenous interleukin (IL)-1ß, IL-6, IL-15, IL-21, tumor necrosis factor (TNF)-α, and interferon (INF)-γ expression in vivo. After the zebrafish were infected with V. vulnificus or S. agalactiae, the LEC immersion treatment suppressed the expression of the inflammatory cytokines IL-1ß, IL-6, IL-15, NF-κb, and TNF-α and induced IL-10 and C3b expression. These findings demonstrate that cinnamaldehyde exhibits antimicrobial activity against aquatic pathogens, even antibiotic-resistant bacterial strains and immune-stimulating effects to protect the host's defenses against pathogen infection in bacteria-infected zebrafish. These results suggest that LEC could be used as an antimicrobial agent and immunostimulant to protect bacteria-infected fish in aquaculture.

Progranulin regulates zebrafish muscle growth and regeneration through maintaining the pool of myogenic progenitor cells.

Myogenic progenitor cell (MPC) is responsible for postembryonic muscle growth and regeneration. Progranulin (PGRN) is a pluripotent growth factor that is correlated with neuromuscular disease, which is characterised by denervation, leading to muscle atrophy with an abnormal quantity and functional ability of MPC. However, the role of PGRN in MPC biology has yet to be elucidated. Here, we show that knockdown of zebrafish progranulin A (GrnA) resulted in a reduced number of MPC and impaired muscle growth. The decreased number of Pax7-positive MPCs could be restored by the ectopic expression of GrnA or MET. We further confirmed the requirement of GrnA in MPC activation during muscle regeneration by knockdown and transgenic line with muscle-specific overexpression of GrnA. In conclusion, we demonstrate a critical role for PGRN in the maintenance of MPC and suggest that muscle atrophy under PGRN loss may begin with MPC during postembryonic myogenesis.

Progranulin compensates for blocked IGF-1 signaling to promote myotube hypertrophy in C2C12 myoblasts via the PI3K/Akt/mTOR pathway.

It is well known that growth hormone (GH)-induced IGF-1 signaling plays a dominant role in postnatal muscle growth. Our previous studies have identified a growth factor, progranulin (PGRN), that is co-induced with IGF-1 upon GH administration. This result prompted us to explore the function of PGRN and its association with IGF-1. In the present study, we demonstrated that, similar to IGF-1, PGRN can promote C2C12 myotube hypertrophy via the PI(3)K/Akt/mTOR pathway. Moreover, PGRN can rescue the muscle atrophy phenotypes in C2C12 myotube when IGF-1 signaling is blocked. This result shows that PGRN can substitute for IGF-1 signaling in the regulation of muscle growth. Our findings provide new insights into IGF-1-modulated complicated networks that regulate muscle growth.

Zebrafish eggs used as bioreactors for the production of bioactive tilapia insulin-like growth factors.

Multiple advantages-including the short generation time, large numbers of fertilized eggs, low cost of cultivation and easy maintenance favor the use of fish as bioreactors for the production of pharmaceutical proteins. In the present study, zebrafish eggs were used as bioreactors to produce mature tilapia insulin-like growth factors (IGFs) proteins using the oocyte-specific zona pellucida (zp3) promoter. The chimeric expression plasmids, pT2-ZP-tIGFs-IRES-hrGFP, in which hrGFP was used as reporter of tilapia IGFs expression, were designed to established Tg (ZP:tIGFs:hrGFP) transgenic lines for the expression of tilapia IGF-1 and IGF-2. Recombinant tilapia IGF-1 and IGF-2 were expressed as soluble forms in cytoplasm of fertilized eggs. The content level of tilapia IGF-1 and IGF-2 were 6.5 and 5.0% of the soluble protein, respectively. Using a simple Ni-NTA affinity chromatography purification process, 0.58 and 0.49 mg of purified tilapia IGF-1 and IGF-2 were obtained, respectively, from 650 fertilized eggs. The biological activity of the purified tilapia IGF-1 and IGF-2 was confirmed via a colorimetric bioassay to monitor the growth stimulation of zebrafish embryonic cells (ZF4), tilapia ovary cells (TO-2) and human osteosarcoma epithelial cells (U2OS). These results demonstrate that the use of zebrafish eggs as bioreactors is a promising approach for the production of biological recombinant proteins.