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Exopolysaccharide (EPS)-producing bacteria were isolated from the intestines of freshwater fish as prebiotics. Among the isolates, Bacillus sp. P1 was the potent EPS producer, with a high EPS production, and was then identified as Bacillus subtilis P1 based on 16S rRNA and biochemical characteristics. The produced microbial EPS was characterized by its functional groups by FTIR, showing a 90.20% correlation to inulin, while the EPS molecular weight was approximately 105 Da with a high PDI (>1.5). Moreover, the EPS from B. subtilis P1 was assessed for prebiotic properties by growing probiotic bacteria, and significant cell growth occurred in sugar-free TSB with 0.5% EPS (p < 0.05). EPS exhibited approximately 55.37% DPPH radical scavenging at 20 mg/mL and inhibited certain fish pathogens at 400 μg/mL (10–13 mm inhibition zone). Low EPS cytotoxicity was confirmed (Oreochromis niloticus) diet supplementation. Nile tilapia growth and immune response were monitored after feeding with control (C), basal diet (BD), and treatment (T): BD + EPS 5 g/kg. In the T-group, the weight gain (WG), % specific growth rate (SGR), and average daily gain (ADG) significantly increased compared to the control (p < 0.05) by week 4, with no negative effects on blood chemistry parameters. Lysozyme activity and respiratory burst activity in T-groups were significantly higher than the control (p < 0.05), with a 50% RLP survival rate of Nile Tilapia infected by Aeromonas veronii in the T-group after a two-week challenge. On the other hand, the proximate analysis revealed higher protein content in the T-group. These findings suggest that EPS from B. subtilis P1 in fish diets efficiently supports fish growth and stimulates innate immune response in Nile Tilapia, thus showing potential as the immunobiotics for aquaculture.

Abstract Background and aim Contamination from increased anthropogenic activities poses a threat to human health as well as the ecosystem. To develop a nanotechnological approach to improve aqua fisheries, we synthesized magnetic hematite nanoparticle-based gel and evaluated its efficacy in a cadmium-polluted closed system to decontaminate water and improve tilapia fish health. Methods Green iron oxide nanoparticles were biosynthesized by the metabolite of bacillus subtilis and incorporated into polyvinyl alcohol to construct a hydrogel by cryogelation. Key findings The cryogel had interconnected macropores with diameters widely ranging between 20 and 200 μm and could be free-floating in water. When applied in cadmium-polluted tilapia culture, this nanogel reduced turbidity and ammonia in the aquarium, adsorbed cadmium from the water with a larger quantity on the gel’s outer surface than in its center., and reduced cadmium concentration in tilapia’s liver, gills, and muscles. Application of this nano-based cryogel reduced the toxic effects of cadmium on tilapia fish. It maintained hepatic and renal cell nuclear integrity as determined by comet assay. This nano-treatment also reversed the cadmium-induced elevations of plasma lipids, glucose, stress marker cortisol, the hepatic enzymes AST and ALT, and the kidney function marker urea, and improved the lymphocytopenia and other hematological functions in tilapia fish intoxicated by cadmium.

Exopolysaccharide (EPS)-producing bacteria were isolated from the intestines of freshwater fish as prebiotics. Among the isolates, Bacillus sp. P1 was the potent EPS producer, with a high EPS production, and was then identified as Bacillus subtilis P1 based on 16S rRNA and biochemical characteristics. The produced microbial EPS was characterized by its functional groups by FTIR, showing a 90.20% correlation to inulin, while the EPS molecular weight was approximately 105 Da with a high PDI (>1.5). Moreover, the EPS from B. subtilis P1 was assessed for prebiotic properties by growing probiotic bacteria, and significant cell growth occurred in sugar-free TSB with 0.5% EPS (p < 0.05). EPS exhibited approximately 55.37% DPPH radical scavenging at 20 mg/mL and inhibited certain fish pathogens at 400 μg/mL (10–13 mm inhibition zone). Low EPS cytotoxicity was confirmed (<1% hemolysis) prior to use as immunobiotics in Nile Tilapia (Oreochromis niloticus) diet supplementation. Nile tilapia growth and immune response were monitored after feeding with control (C), basal diet (BD), and treatment (T): BD + EPS 5 g/kg. In the T-group, the weight gain (WG), % specific growth rate (SGR), and average daily gain (ADG) significantly increased compared to the control (p < 0.05) by week 4, with no negative effects on blood chemistry parameters. Lysozyme activity and respiratory burst activity in T-groups were significantly higher than the control (p < 0.05), with a 50% RLP survival rate of Nile Tilapia infected by Aeromonas veronii in the T-group after a two-week challenge. On the other hand, the proximate analysis revealed higher protein content in the T-group. These findings suggest that EPS from B. subtilis P1 in fish diets efficiently supports fish growth and stimulates innate immune response in Nile Tilapia, thus showing potential as the immunobiotics for aquaculture. [ABSTRACT FROM AUTHOR]

Background and aim: Contamination from increased anthropogenic activities poses a threat to human health as well as the ecosystem. To develop a nanotechnological approach to improve aqua fisheries, we synthesized magnetic hematite nanoparticle-based gel and evaluated its efficacy in a cadmium-polluted closed system to decontaminate water and improve tilapia fish health. Methods: Green iron oxide nanoparticles were biosynthesized by the metabolite of bacillus subtilis and incorporated into polyvinyl alcohol to construct a hydrogel by cryogelation. Key findings: The cryogel had interconnected macropores with diameters widely ranging between 20 and 200 μm and could be free-floating in water. When applied in cadmium-polluted tilapia culture, this nanogel reduced turbidity and ammonia in the aquarium, adsorbed cadmium from the water with a larger quantity on the gel’s outer surface than in its center., and reduced cadmium concentration in tilapia’s liver, gills, and muscles. Application of this nano-based cryogel reduced the toxic effects of cadmium on tilapia fish. It maintained hepatic and renal cell nuclear integrity as determined by comet assay. This nano-treatment also reversed the cadmium-induced elevations of plasma lipids, glucose, stress marker cortisol, the hepatic enzymes AST and ALT, and the kidney function marker urea, and improved the lymphocytopenia and other hematological functions in tilapia fish intoxicated by cadmium.Significance: The nano product of this work has many advantages. It is cheap, green, safe, can be easily manufactured, replaced, or removed from the aquaria, and proven efficient to clean aqua fisheries’ water. The concentration of NPs can be adjusted in the hydrogel, and the utilization of magnetic α-Fe2O3 NPs allows for the removal of the released particles by application of a magnetic field. [ABSTRACT FROM AUTHOR]

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Burn injury remains a health problem, specifically in Indonesia. In major burns, xenograft has been proved to be useful as temporary wound coverage. However, some xenografts are not widely available due to cultural, financial and religious backgrounds, or have an unesthetic appearance, such as the scaly appearance of tilapia fish xenograft.Striped catfish (Pangasius hypophthalmus) is a scaleless fish that has abundant type 1 collagen. This study aimed to compare striped catfish skin to commonly used xenograft (Nile tilapia and porcine skin) as xenograft material for burn wound. In this experimental study, nine different skin samples of striped catfish, Nile tilapia and porcine were prepared and histologically examined using hematoxylin-eosin stained samples. Macroscopic and microscopic features of each sample were documented and analysed. The macroscopic skin appearances of striped catfish were hairless and scaleless with black-silver color and moderate thickness. As for microscopic features, the epidermal thickness of striped catfish skin (8.49±1.60 μm) was significantly different to both Nile tilapia (2.18±0.37 μm; p<0.001) and porcine skin (42.22±14.85 μm; p=0.002). The dermal thickness of striped catfish skin (288.46±119.04 μm) was similar to Nile tilapia (210.68±46.62 μm; p=0.783) but differs significantly to porcine skin (1708.44±505.12 μm; p<0.001). The integrity and collagen organization of striped catfish was also similar to tilapia based on semi-quantitative histology scoring system (p>0.05). Striped catfish had potential macroscopic appearance and comparable microscopic features to Nile tilapia; smoother macroscopic appearance, thicker epidermis, and similar dermis thickness. Therefore, we believe it can be potentially used as a xenograft material. Further studies are required to evaluate the effectiveness and feasibility of striped catfish xenograft in burn wound management. [ABSTRACT FROM AUTHOR]

This study aimed to study the effects of single or combined dietary supplementation of xylooligosacharides (XOs), prebiotics derived from agricultural waste and mixed probiotics (Bacillus subtilis TISTR 008 and Lactobacillus plantarum TISTR 1854) on growth performance, flesh quality, health condition and disease resistance in Nile tilapia (Oreochromis niloticus). Fish received four types of diets: a basal diet (control); XOs (prebiotics); a mixture of Bacillus subtilis TISTR 008 and Lactobacillus plantarum TISTR 1854 (probiotics); and a combination of XOs and a probiotic mixture (synbiotics) for 56 days. The results show that dietary prebiotics, probiotics, and synbiotics improved growth performance including final body weight, weight gain, average daily gain, and protein efficiency ratio compared to the control diet. Interestingly, the feed conversion ratio was improved by dietary prebiotics, probiotics, and synbiotics supplementation. Concurrently, innate immunity parameters such as total antioxidant, lysozyme, catalase, and glutathione S transferase were mostly higher in fish fed the prebiotics, probiotics, and synbiotics diets. Moreover, we observed significant increases in digestive enzyme activities, including protease, amylase, and lipase, in fish fed probiotic diets. After the feeding trial, fish were intraperitoneally injected with Streptococcus agalactiae, and the cumulative 14-day mortality rate was calculated. High survival rates were observed in all groups that received supplementation with prebiotics, probiotics, or synbiotics in their feed. This improvement is correlated with an increase in the transcriptional levels of immune- and growth-related factors. Interestingly, this study highlights the use of prebiotics and synbiotics containing XOs to boost the PUFA n-3 and n-6 content in the fish fillets. Our findings indicate that adding XOs as prebiotics to the diet significantly enhances the overall performance of fish when compared to the effects of probiotics and synbiotics. In summary, XOs may have the potential as organic compounds derived from agricultural waste for specific probiotic and synbiotic products in the aquaculture industry when combined in the right proportions.

Functional trace elements and vitamins can boost immunity and anti-oxidative response in aquatic animals with effects on nutritional physiology. Nano-selenium (nano-Se) and vitamin C (VC) have been used as immunomodulators and antioxidants in fish feed. The present work was performed to determine the protective effects of diets supplemented with different combinations of nano-Se and VC on Nile tilapia (Oreochromis niloticus). Triplicate groups of 20 fish/tank (13.87 ± 0.10 g) were reared and fed with basal diet (control-T1) (without supplementation of nano-Se and VC) and three experimental diets as T2, T3, and T4 (100, 200, and 300 mg/kg VC respectively) with a pre-determined dose of nano-Se (1.0 mg/kg) for 90 days. Different immune indices, haemato-biochemical, and antioxidant activities were measured at the end of the first, second, and third months of feeding. The findings depicted that significantly (p < 0.05) higher growth was observed in T4. Red blood cells, white blood cells, and haemoglobin were found significantly (p < 0.05) higher in T4 for the third month. Serum biochemical-immunological indices (alkaline phosphatase, glucose, cholesterol, lysozyme, myeloperoxidase, total protein, albumin and globulin) followed the same trend. Furthermore, antioxidant assays such as catalase, superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and malondialdehyde were significantly (p < 0.05) improved in T4 for the third month. Significantly (p < 0.05) least cumulative mortality against Aeromonas hydrophila was obtained in the fish-fed diets incorporated with nano-Se and VC. Therefore, dietary supplementation with nano-Se and VC is noteworthy for improving growth, serum biochemical status, immune response, antioxidant status, and disease resistance. [ABSTRACT FROM AUTHOR]

We compared the benefits of using extruded feed (EF), against pelleted feed (PF) to guide cage culture investments in Great Lakes. Three out of six cages in the same farm had fish that were fed EF and the other half, belonging to a different farm had fish that were fed PF. The diets were similar in crude protein, lipid and energy content. However, the fiber content in PF was 4 times higher than that of EF. The fish fed on EF grew better (438.0 ± 7.4 g) than the fish fed on PF (220.8 ± 2.9 g). The cost of production for EF was about 26% lower than for PF, primarily because of better feed utilization. The load of P and N for PF diet was 59% and 29% higher, respectively, than when EF was used. Therefore, EF feed delivered better economic gains with lower environmental impact than PF feed. [ABSTRACT FROM AUTHOR]

Unusual fish mortalities in aquaculture threaten global food security and carry significant socio-economic burdens. In 2018, Nile tilapia (Oreochromis niloticus) suffered unusual patterns of mortalities, attributed to disease-causing agents in Lake Volta cage aquaculture. In recent times, disease investigations have shifted from single to consideration of multiple factors to understand the puzzling range of causal risk factors. This study therefore aimed at expanding on tilapia mortality risk factors, while documenting fish health and Lake Volta management practices for sustainable aquaculture. We interviewed relevant aquaculture stakeholders operating on Lake Volta and conducted thematic analysis on their responses to map out mortality risk factors and management practices. The identified risk factors were conceptualized in established models of causation web and Social-Ecological System to explain the practical significance of the findings. The results showed that the risk factors of tilapia mortalities are a combination of pathogens and non-infectious factors mediated by weak law enforcement. The results further suggested mortality reinforcing mechanisms through the horizontal transmission of pathogens, namely, Streptococcus agalactiae and Infectious Spleen and Kidney Necrosis Virus. Moreover, the recognition of weak enforcement as a possible factor reinforcing human activities is a non-infectious route that can be deleterious to fish health. Health management practices comprised phytotherapy, vaccination, heat shock treatment, biological controls, and best husbandry practices. Lake management involves creating a waterfront buffer of 85.34 m, surveillance, and executing the framework guiding aquaculture development on the Lake. The findings are suggestive of complementary quantitative studies that augment the qualitative evidence herein. Such follow up studies can disclose precise mortality risk factors to inform policy directives and effective remedial strategies that can secure fish and lake health.

Stimulator of interferon genes (STING) plays important roles in innate immunology. In this study, we isolated the STING gene in Nile tilapia, termed OnSTING. Using quantitative RT–PCR, we explored the expression patterns of the OnSTING gene. Using dual-luciferase reporter assays, we revealed the effect of STING overexpression on nuclear factor κB (NF-κB), IFN and AP activation in HEK 293 cells. Using coimmunoprecipitation, the interaction of STING and TRIF was studied. The effect of OnSTING overexpression on the antibacterial activity in tilapia was investigated. The results showed that upon stimulation with Streptococcus agalactiae , the OnSTING transcript was upregulated in all the tested tissues. OnSTING mRNA levels were very stable from 2.5 to 8.5 dpf. Moreover, OnSTING, OnIFN and IRF3 expression was induced by LPS, Poly (I:C), S. agalactiae WC1535 and DCPS in Nile tilapia macrophages. Overexpression of OnSTING and OnDDX41 increased NF-κB activation in HEK293T cells and slightly increased IFN-β activation but had no effect on AP-1 activation. OnSTING interacted with OnDDX41 and OnTBK1. However, OnSTING did not interact with TRIF. OnSTING overexpression in vivo decreased the sensitivity of tilapia to S. agalactiae infection. These results are helpful for clarifying the innate immune response against bacterial infection in Nile tilapia. [ABSTRACT FROM AUTHOR]

The teleost non-specific cytotoxic cell (NCC), as the evolutionary precursors of NK cells, is an important cytotoxic cell population in the innate immune system of teleost. We have recently realized that costimulatory CD80/86 have conservation in structural and interactional features with its ligand CD28 in Nile tilapia (Oreochromis niloticus). However, the ability of CD80/86 to regulate NCC activity has not been fully investigated. In the present study, we first obtained the recombinant fusion CD80/86 protein from O. niloticus (rOn-CD80/86). Then, NCC incubation with rOn-CD80/86 resulted in a significant production of NCC effector cytokines, including tumor necrosis factor-alpha, cellular apoptosis susceptibility and NK-lysin. Furthermore, NCC treatment with rOn-CD80/86 could significantly improve the ability to kill kidney cells of Grass carp (CIK) and up-regulate the activities of caspase-1 and caspase-3 in CIKs. The yeast, two-hybrid assay showed that On-CD80/86 cannot directly interact with non-specific cytotoxic cell receptor protein-1 of O. niloticus (On-NCCRP-1). The single-cell RNA-Seq data of Nile tilapia head kidney lymphocytes analysis found On-CD28 did not exhibit expression on NCCs subsets. The above results suggest that costimulatory molecules On-CD80/86 is independent of On-NCCRP-1 and On-CD28 receptor in modulating NCC killing activity in vitro of Nile tilapia. The results also provide more insights into the mechanism of NCC activity regulation. [ABSTRACT FROM AUTHOR]

Bacteria or viral outbreaks can cause tilapia hemorrhage, ensuring considerable volume of hemoglobin (Hb) into the tissue. However, the hemoglobin toxicity on tissue and high doses also effect on tissue this phenomena is still under consideration. Therefore, current study exploited Nile tilapia kidney (NTK) cells to deeply expose the toxic effect of Hb on NTK cells. Toxicity of Hb on NTK cells was determined in terms of cells growth, expression of iron metabolism and inflammation-related genes, consequently examined antioxidant-related enzymes genes expression, intracellular iron and reactive oxygen species (ROS) contents, and apoptosis-related genes expression. The results showed that Hb and heme significantly inhibited NTK cells growth and up-regulated iron metabolism-related genes expression in different degrees. The Hb and heme activated the expression of pro-inflammatory cytokines (TNF-α, tumor necrosis factor-α; IL-1β, interleukin 1β; IL-6, interleukin 6), the anti-inflammatory factor (IL-10, interleukin 10) and the chemotactic factors (IL-4, interleukin 4; IL-8, interleukin 8) through NF-κB pathway, meanwhile activated the expression of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Moreover, the Hb significantly increased intracellular iron and ROS contents while the expression of apoptosis-related genes was significantly activated by both Hb and heme. Current investigation suggested that high oxidative activity of Hb could activate iron metabolism- and inflammation-related genes expression, and increase intracellular iron and ROS levels, lead to up-regulated the expression of apoptosis genes in NTK cells. • Hb promoted the expression of inflammation-related genes. • Hb activated the expression of genes related to iron metabolism. • Hb enhanced the expression of antioxidant-related genes. • Hb increased intracellular iron and ROS contents. • Hb activated the expression of apoptosis-related genes. [ABSTRACT FROM AUTHOR]

High-carbohydrate diet could achieve cost-sparing effect in aquafeed, but it may cause adverse effects on the growth condition or health status of fish. In order to reduce the adverse effects caused by high carbohydrate diet, mannan oligosaccharides (MOS), a commonly used prebiotics, was used as the feed additive to feed juvenile Nile tilapia (Oreochromis niloticus) (1.19 ± 0.01g) for ten weeks. Three treatments including CON (35% carbohydrate diet), HC (45% carbohydrate diet) and HM (45% carbohydrate supplemented diet with 5 g/kg MOS) were involved. The results showed that MOS supplementation increased the weight gain and body length of juvenile Nile tilapia compared with the HC group. Addition of MOS decreased serum glucose and liver glycogen by increasing enzymes activity related to glycolysis. Furthermore, supplementation of MOS decreased the high carbohydrate diet induced triglycerides accumulation in liver by reducing the expression level of genes related to TG synthesis. Dietary MOS also down-regulated the gene expression level of inflammation factors in liver. Intestinal bacterial composition analyses showed that supplementation of MOS in high carbohydrate diet altered the gut microbial composition and enriched pathways related to the glucose metabolism based on KEGG analyses. In general, our results demonstrated that MOS supplementation in high carbohydrate diet could regulate glucose and lipid homeostasis which may be related to the alteration of gut microbiota. These findings shed light on the application of prebiotics to increase the growth performance, alleviate the metabolic disorders and regulate inflammatory response in aquaculture. • MOS increased growth condition. • MOS alleviated metabolism disorders. • MOS attenuated inflammatory response. • MOS altered gut microbial composition. [ABSTRACT FROM AUTHOR]

Anti-Müllerian hormone (amh), an important regulator of gonad development in male teleosts, regulates the development and differentiation of germ cells. We performed transcriptional knock-down of amh in Nile tilapia (Oreochromis niloticus) using antisense RNA technology, resulting in down-regulation in the expression of amh transcription and Amh protein in males. Compared with the control groups, the fish in treatment groups with down-regulated amh had increased weight and an extremely significant decrease in the gonadosomatic index. Hematoxylin–eosin staining revealed impaired testis development and significant reductions in numbers of sperm. Serum estradiol levels were significantly increased, and the levels of testosterone, luteinizing hormone, and follicle-stimulating hormone were significantly decreased. RNA-sequencing analysis of the fish in the down-regulated amh and control groups identified 12,048 differentially expressed genes, of which 1281 were up-regulated and 10,767 were down-regulated. Kyoto Encyclopedia of Genes and Genomes analysis revealed that differentially expressed genes related to growth and development were mainly enriched in the Cell cycle, Endocytosis, TGF-beta signaling pathway, Wnt signaling pathway, FoxO signaling pathway, Insulin signaling pathway, and MAPK signaling pathway. The RNA-sequencing data accuracy was verified by qRT-PCR analysis of the expression levels of selected differentially expressed genes. The abnormal TGF-beta signaling pathway may cause fish weight gain, testis dysplasia, and abnormal spermatogenesis: smad5, smad3a, tgfb2, tgfbr1b, gsdf, and amh were significantly down-regulated. These findings indicated that antisense RNA technology has strong application prospects and can specifically knock down amh in Nile tilapia, resulting in an abnormal TGF-beta signaling pathway, inhibiting testis development and inducing weight gain. [ABSTRACT FROM AUTHOR]

TLR3 plays a crucial role in innate immunity. In the present study, OnTLR3 was identified in the Nile tilapia Oreochromis niloticus , with a conserved LRR domain and a C-terminal TIR domain. OnTLR3 was broadly expressed in all tissues tested, with the highest expression levels in the blood and the lowest in the kidney. TLR3 mRNA could be detected from pharyngula (2.5 dpf) to late larva (8.5 dpf) during embryonic and larval development. Moreover, the expression level of OnTLR3 was clearly altered in all five tissues after Streptococcus agalactiae infection in vivo and could be induced by LPS, poly(I:C), S. agalactiae WC1535 and △CPS in Nile tilapia macrophages. When OnTLR3 was overexpressed in 293 T cells, it was distributed in the cytoplasm and could significantly increase NF-κB activation. The pulldown assays showed that OnTLR3 interacted with both OnMyD88 and OnTRIF. The binding assays revealed the specificity of OnTLR3 for pathogen-associated molecular patterns (PAMPs) and bacteria that included S. agalactiae , Aeromonas hydrophila and poly(I:C), LPS and PGN. Taken together, these findings suggest that OnTLR3, as a pattern recognition receptor (PRR), might play an important role in the immune response to pathogen invasion. • TLR3 gene was identified in Nile tilapia and was upregulated after S. agalactiae challenge. • TLR3 induced by LPS, Poly I: C, wild and mutant type S. agalactiae in in vitro. • TLR3 interact with MyD88 and TRIF. • The overexpression of TLR3 significantly induced NF-κB activity in cell line. • Binding assays revealed the specificity of OnTLR3 for pathogen-associated molecular patterns (PAMPs). [ABSTRACT FROM AUTHOR]

Streptococcosis is the leading bacterial disease impacting Nile tilapia (Oreochromis niloticus) and causes substantial economic losses in China. This study assessed the resistance and tolerance of three Nile tilapia (88, 99, and NG) to Streptococcus agalactiae infection. Survival rates were monitored, and samples were collected from blood, liver, and spleen at 0, 1, 2, 5, 7, and 14 days post-infection. Serum biochemical parameters, hepatic antioxidant enzymes, and the expression of related antioxidant and immune genes were measured. Results showed that strain 88 had superior resistance, with the highest survival rate, reduced liver damage, and lower alanine aminotransferase and alkaline phosphatase levels at 1 and 5 days post-infection. This strain also had higher serum cholesterol and triglyceride levels between days 5 and 14. Antioxidant activities increased in all strains post-infection, with strain 88 showing significantly higher superoxide dismutase (SOD) activity and elevated catalase (CAT) and SOD gene expressions; this indicated enhanced control of reactive oxygen species and reduced tissue damage. Additionally, strain 88 exhibited lower levels of inflammatory markers (TNF-α , IL-1β , IL-10) with higher IgM levels and superior MHC-II expression during early infection, which demonstrated a strong immune response. These results indicate that strain 88 is a promising candidate for selective breeding to improve streptococcosis resistance in tilapia. • Nile tilapia strain 88 shows highest survival rate and reduced liver damage. • Nile tilapia strain 88 exhibits enhanced antioxidant activity post-infection. • Nile tilapia strain 88 exhibits strong immune response and lower inflammation. • Nile tilapia strain 88 is a promising candidate for selective breeding. [ABSTRACT FROM AUTHOR]

Tripartite motif (TRIM) proteins play a regulatory function in cancer, cell apoptosis and innate immunity. To understand the role of TRIM39 in Nile tilapia (Oreochromis niloticus), TRIM39 cDNA was isolated. The total length of TRIM39 cDNA was 5025 bp. The deduced OnTRIM39 protein contains 549 amino acids and has conserved domains of the TRIM family, which are the RING, B‐box, coiled‐coil and PRY‐SPRY domains. OnTRIM39 mRNA was widely expressed in various tissues. After challenge with Streptococcus agalactiae and stimulation with polyinosinic polycytidylic acid [poly (I:C)] and lipopolysaccharides (LPS), the amount of OnTRIM39 transcript was changed in various tested tissues. OnTRIM39 overexpression increased NF‐κB activity. OnTRIM39 was present in the cytoplasm. Mass spectrometry of proteins pulled down with recombinant OnTRIM39 showed that 250 proteins potentially interact with OnTRIM39. The authors selected I3K4I3 from the 250 candidate proteins to verify its interaction with TRIM39. They also selected I3KL45, a member of the same 14‐3‐3 protein family, to verify its interaction with TRIM39. The results of pull‐down assays showed that OnTRIM39 interacted with both I3K413 and I3KL45. These results contribute to further study of the innate immune mechanism of tilapia. [ABSTRACT FROM AUTHOR]

The economic viability of tilapia cage culture in Lake Victoria was assessed using a profitability analysis model as the main decision support tool. One and five cages of 8 m3 (A), 62.5 m3 (B), and 471 m3 (C) were assessed. The break-even price (US$4.6 kg−1) for one cage of A appeared higher than the tilapia farm gate price in Kenya (US$3.5 kg−1), suggesting unprofitability of the venture. The decreased break-even price relative to increase in cage numbers showed economies of scale throughout the cage volume ranges. The longest payback period (PBP) for A (8 years) implied a risky venture. This was reaffirmed by an internal rate of return (IRR) of < 50% and negative Net present value (NPV) in the first two years of operations. The study affirmed the economic viability of operating large cage volumes (B or C) for Nile tilapia and for broader applicability to other Great Lakes. [ABSTRACT FROM AUTHOR]

A pseudotuberculosis pathogen, Photobacterium damselae subsp. piscicida (Pdp), has caused enormous economic damage to yellowtail aquaculture in Japan. The Ivy gene has been discovered in plasmid of Pdp , and it has been proposed that it may help bacteria evade lysozyme-mediated lysis during interaction with an animal host. However, the lysozyme-inhibiting activity of Pdp -derived Ivy (Ivy-Pdp) is unknown, and it is unclear whether it acts as a virulence factor for host biophylaxis. In this study, the inhibitory effect of Ivy-Pdp on lysozyme was evaluated by expressing and purifying the recombinant Ivy-Pdp protein (rIvy-Pdp). The rIvy-Pdp protein inhibited hen egg white lysozyme activity in an rIvy-Pdp-concentration-dependent manner, and its inhibitory effect was similar under different temperature and pH conditions. The serum and skin mucus of the yellowtail (which is the host species of Pdp), Japanese flounder, and Nile tilapia showed bacteriolytic activity. In contrast, the addition of rIvy-Pdp inhibited the lytic activity in the serum of these fish species. In particular, it significantly inhibited lytic activity in the serum and skin mucus of Nile tilapia. On the basis of these results, we suggest that Ivy-Pdp is a temperature- and pH-stable lysozyme inhibitor. Additionally, Ivy-Pdp inhibited the lytic activity of lysozyme, which is involved in host biophylaxis. In summary, we inferred that Ivy-Pdp is an important factor that diminishes the sterilization ability of C-type lysozyme when Pdp infects the host. • Ivy-Pdp highly preserved the CKPHDC motif, as with Ivy derived from known pathogenic bacteria. • Ivy-Pdp inhibited HEWL lytic activity, regardless of temperature and pH. • Ivy-Pdp inhibited lytic activity of yellowtail and Nile tilapia serum. [ABSTRACT FROM AUTHOR]

Probiotic feeding is a new strategy of healthy fish farming. To examine the effects of adding Torulaspora sp. GXUS02 and Metschnikowia sp. GXUS03 on the growth and immune parameters of Nile tilapia, a feeding trial was conducted in this study using a feed dose of 108 CFU/g to cultivate tilapia (100 ±15 g) for 8 weeks. The growth performance, serum parameters, intestinal microbiota and the anti‐Streptococcus agalactiae ability of tilapia were used to evaluate the effects of the yeast supplemented group. The results reveal that both yeast diets could significantly improve the growth performance of tilapia by significantly increased the activities of protease and xylanase. Amongst the serum parameters, the lysozyme activity and the amount of complement C3 and C4 of tilapia fed with GXUS03 were significantly increased, and the ability to fight Streptococcus agalactiae was significantly increased (p < 0.05). Both yeast diets could change the intestinal microflora structure of tilapia. GXUS02 could significantly increase the amount of Sarcina and significantly decrease the amount of Microdiscus. In the intestinal microbiota of tilapia fed with GXUS03, Golenkinia‐longispicula and LD29 were significantly increased, whilst the amount of Microdiscus was significantly decreased. In the analysis of intestinal microbiota diversity of tilapia fed with two yeast diets for 30 and 60 days, the stability of the intestinal microbiota of tilapia was better. In conclusion, the addition of two kinds of yeast had a good probiotic effect on tilapia culture, and GXUS03 exhibited the best probiotic effect in promoting the growth and immunity of tilapia. [ABSTRACT FROM AUTHOR]

• The cDNA sequence of DDX43 was identified from tilapia (Oreochromis niloticus). • Expressions of DDX43 mRNAs were altered after Streptococcus agalactiae , LPS, and poly I:C stimulation. • The overexpression of OnDDX43 could significantly upregulate IFN-β activity in 293 T cells. • OnDDX43 interacted with both IPS-1 and TRIF. DDX43 is one of the members of the DExD/H-box protein family, and emerging data suggest that it may play an important role in antiviral immunity across mammals. However, little is known about DDX43 in the fish immune response. In this study, we isolated the cDNA sequence of ddx43 in Nile tilapia (Oreochromis niloticus). The ddx43 gene was 2338 bp in length, contained an open reading frame (ORF) of 2064 bp and encoded a polypeptide of 687 amino acids. The predicted protein of On DDX43 has three conserved domains, including the RNA binding domain KH, DEAD-like helicase superfamily DEXDc and C-terminal HELICc domain. In healthy Nile tilapia, the Onddx43 transcript was broadly expressed in all examined tissues, with the highest expression levels in the muscle and brain and the lowest in the liver. After challenge with Streptococcus agalactiae , lipopolysaccharides (LPS) and polyinosinic polycytidylic acid (Poly I:C), the expression level of Onddx43 mRNA was upregulated or downregulated in all of the tissues tested. Overexpression of On DDX43 in 293 T cells showed that it has a positive regulatory effect on IFN-β. The subcellular localization showed that On DDX43 was expressed in the cytoplasm. We performed further pull-down assays and found that On DDX43 interacted with both interferon-β promoter stimulator1 (IPS-1) and TIR domain-containing adaptor inducing interferon-β (TRIF). [ABSTRACT FROM AUTHOR]

Tumour necrosis factor receptor-associated factor 6 (TRAF6) is a key adaptor protein that plays important role in signalling pathways triggered by the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) superfamily, which is highly involved in innate immunity. In this study, we investigated expression patterns and preliminary functional analyses of Nile tilapia traf6. In healthy fish, traf6 transcripts were broadly expressed in all examined tissues with the highest expression level in the blood and the lowest in the liver. traf6 was also detected at various embryonic developmental stages. After challenge with S. agalactiae in vivo, upregulated mRNA expression of traf6 was observed in most examined tissues. Moreover, traf6 expression could be significantly induced in Nile tilapia macrophages by treatment with LPS, Poly I: C and S. agalactiae. In addition, overexpression in HEK293T cells showed that TRAF6 was distributed in the cytoplasm and could significantly increase NF-κB activation. Co-immunoprecipitation (Co-IP) assays showed that TRAF6 could interact with IRAK1 (interleukin-1 receptor associated kinase 1), which also plays a vital role in the TLR/IL-1R signalling pathway. In vivo, TLR2, TLR21 and TLR13b overexpression could upregulate traf6 expression levels, which indicates that TRAF6 is involved in the signal transduction of TLR2, TLR21 and TLR13b. These findings suggest that TRAF6 plays important roles in the immune response to pathogen invasion. [ABSTRACT FROM AUTHOR]

High level of carbohydrate in aquafeed could achieve cost-sparing effect, but it may cause adverse effects on flesh quality of aquatic products. An eight-week trial was conducted to investigate whether oligosaccharides-supplementation, including Galacto-oligosaccharides (GOS) and xylo-oligosaccharide (XOS), could systematically improve the growth performance, texture characteristics and nutrition composition of Nile tilapia fed with high-carbohydrate diet. The results indicated that GOS-supplementation improved the amino acid composition, while XOS-supplementation showed beneficial effects on growth performance. High-carbohydrate diet had adverse effects on fillet texture, while oligosaccharide-supplementation regulated the expression of muscle development-related genes to help restoring muscle texture properties. Furthermore, either high-carbohydrate or addition of oligosaccharides could change the intestinal microbiota composition and their metabolites. Further correlation analysis suggested that intestinal microbiota may account for the improvement in fish growth condition and texture characteristics. Application of oligosaccharides may be an innovative strategy for flesh quality modulation in aquaculture.

This study aimed to investigate the effects of endocrine disruptors 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) on Nile tilapia (Oreochromis niloticus) development, focusing on gonadal histological factors. Concentrations of estrogens E2 and EE2 ranging from 250 to 1000 ng·L−1 can produce intersex individuals, significantly decreasing the condition factor as the concentrations increased. These concentrations could also induce the development of morphological anomalies. Increasing the concentration of estrogens by one order of magnitude (µg·L−1) was lethal for Nile tilapia larvae, with no effect on the incubation time and percentage of larvae hatching. Additionally, morphological anomalies and developmental problems were observed. Estrogens applied at a concentration of 160 µg·L−1 for 28 days caused the birth of a small number of intersex individuals in Nile tilapia, but generated almost entirely female populations in hormonal treatments. Furthermore, the gonads of fish exposed to the estrogens were smaller and less developed, without any significant difference between E2 and EE2. Variation in the exposure time (one to 4 weeks) of Nile tilapia to estrogens (160 µg·L−1) resulted in the appearance of intersex individuals and the development of morphological anomalies, regardless of the exposure time. [ABSTRACT FROM AUTHOR]

Infectious diseases represent one of the major challenges to sustainable aquaculture production. Rapid, accurate diagnosis and genotyping of emerging pathogens during early‐suspected disease cases is critical to facilitate timely response to deploy adequate control measures and prevent or reduce spread. Currently, most laboratories use PCR to amplify partial pathogen genomic regions, occasionally combined with sequencing of PCR amplicon(s) using conventional Sanger sequencing services for confirmatory diagnosis. The main limitation of this approach is the lengthy turnaround time. Here, we report an innovative approach using a previously developed specific PCR assay for pathogen diagnosis combined with a new Oxford Nanopore Technologies (ONT)‐based amplicon sequencing method for pathogen genotyping. Using fish clinical samples, we applied this approach for the rapid confirmation of PCR amplicon sequences identity and genotyping of tilapia lake virus (TiLV), a disease‐causing virus affecting tilapia aquaculture globally. The consensus sequences obtained after polishing exhibit strikingly high identity to references derived by Illumina and Sanger methods (99.83%–100%). This study suggests that ONT‐based amplicon sequencing is a promising platform to deploy in regional aquatic animal health diagnostic laboratories in low‐ and medium‐income countries, for fast identification and genotyping of emerging infectious pathogens from field samples within a single day. [ABSTRACT FROM AUTHOR]

The farming of Nile tilapia (Oreochromis niloticus) has faced the challenges of infections, especially by Streptococcus However, solving this problem by using antibiotics will cause other problems, such as drug residue that can directly affect consumers and an increase in antibiotic resistance to bacteria. Therefore, probiotics should be an alternative to control bacterial diseases. This study aimed to investigate the optimum level of mixed probiotic supplementation. The experiment was designed to include six treatments (the control diet and probiotic‐supplemented diets at 0.5, 1.0, 2.0, 5.0 and 10.0%). The mixed probiotic was composed of 3.1 × 108 CFU of Lactobacillus sp. and 4.6 × 106 CFU of Saccharomyces cerevisiae. After feeding for 30 days, tilapias from each replication were injected with a vaccine containing Streptococcus agalactiae to study the immune gene expression. The results showed that this mixed probiotic can enhance the growth and immune system of tilapias, and the most effective level was at 0.5% with consideration for high ADG, low FCR, and high protective efficiency against S. agalactiae infection. Moreover, toll‐like receptor 9 gene and immunoglobulin gene expressions after vaccination for 24 hours were significantly higher than the control. The relative percent survival was the highest at 78.13%. This mixed probiotic can be used for Streptococcosis control in tilapia farms because it can reduce the diet cost and induce both the growth and immune system of tilapias. [ABSTRACT FROM AUTHOR]

In the present work, a total 180 monosex male Nile tilapia fingerlings (15.73 ± 0.05 g) were stocked in 150-l FRP tanks categorised into four diet groups with triplicate each and fed with dietary nano-selenium-supplemented diets at different concentration (T1—0, T2—0.5, T3—1.0 and T4—2.0 mg/kg of feed) for 90 days and different nutrition physiological parameters (feed utilization, haematology, serum biochemistry), immune response and antioxidant were analysed during pre- and post-challenge against Aeromonas hydrophila. The study results depicted that significantly (p < 0.05) better growth and feed utilization (absolute weight gain, specific growth rate, average daily gain, protein efficiency ratio, food conversion ratio) found in fish fed diet supplemented with 1 mg/kg of nano-Se. Significantly (p < 0.05) improved haematological (red blood cells, haemoglobin, white blood cells, platelets) and serum biochemical parameters (alanine aminotransferase, aspartate aminotransferase, glucose, cholesterol, triglycerides) observed in the same diet group. The same trend was followed by immune parameters (nitro blue tetrazolium, lysozyme activity, myeloperoxidase, total immunoglobulin). Also observed the statistically (p < 0.05) improved antioxidant activities (catalase, superoxide dismutase, glutathione peroxides, glutathione reductase, glutathione S-transferase, malondialdehyde, total antioxidant capacity) in the same diet group. Relative percent survival after the fishes challenged with A. hydrophila was significantly (p < 0.05) differed. The findings suggested that supplementation of 1 mg/kg of dietary nano-Se could able to ameliorate nutrition physiology, immunity, antioxidant activity and disease resistance in tilapia and proved that it may be one of the best element for fish farmers to increase the production in an economically feasible way. [ABSTRACT FROM AUTHOR]

A high-carbohydrate diet could achieve a protein-sparing effect, but it may cause negative impacts on the growth condition of fish due to their poor utilisation ability of carbohydrate. How to reduce the adverse effects caused by a high-carbohydrate diet is important for the development of aquaculture. In the present study, we aimed to identify whether inulin could attenuate the metabolic syndrome caused by a high-carbohydrate diet in fish. Nile tilapia (Oreochromis niloticus) (1·19 (sd 0·01) g) were supplied with 35 % carbohydrate (CON), 45 % carbohydrate (HC) and 45 % carbohydrate + 5 g/kg inulin (HCI) diets for 10 weeks. The results showed that addition of inulin improved the survival rate when fish were challenged with Aeromonas hydrophila, indicating that inulin had an immunostimulatory effect. Compared with the HC group, the HCI group had lower lipid accumulation in liver and the gene expression analyses indicated that addition of inulin down-regulated genes related to lipogenesis and up-regulated genes relevant to β-oxidation significantly (P < 0·05). Higher liver glycogen and glucose tolerance were found in the HCI group compared with the HC group (P < 0·05). These results indicated that inulin could alleviate the metabolic syndrome induced by a high-carbohydrate diet. Furthermore, addition of inulin to a high-carbohydrate diet changed the intestinal bacterial composition and significantly increased the concentration of acetic acid and propionic acid in fish gut which have the potential to increase pathogen resistance and regulate metabolic characteristics in fish. Collectively, our results demonstrated a possible causal role for the gut microbiome in metabolic improvements induced by inulin in fish. [ABSTRACT FROM AUTHOR]

• TLR13a and TLR13b genes were identified from tilapia (Oreochromis niloticus). • Expressions of TLR13a and TLR13b mRNAs were altered after Streptococcus agalactiae challenge. • The TLR13a and TLR13b mRNAs were detected in various embryonic developmental stages. • Both OnTLR13a and OnTLR13b could interact with OnMyd88. • Both OnTLR13a and TLR13b can combine with S. agalactiae 23S rRNA. Toll-like receptors (TLRs) play a crucial role in the innate immune system, which is the first line of defence against pathogens and pathogenic products in fish. In the present study, we cloned the full-length cDNA and genome sequences of two TLR13 s (OnTLR13a, OnTLR13b) from Nile tilapia (Oreochromis niloticus). TLR family motifs, i.e., the leucine-rich repeat (LRR) domains and Toll/interleukin (IL)-1 receptor (TIR) domains, were conserved in the putative proteins OnTLR13a and OnTLR13b, with fifteen LRR domains and one TIR domain. Four exons and three introns were identified in the OnTLR13a genome sequence, and three exons and two introns were identified in the OnTLR13b genome sequence. In healthy Nile tilapia tissues, OnTLR13a and OnTLR13b were ubiquitously expressed in all 11 tested tissues/organs. The highest expression levels were observed in the spleen (OnTLR13a) and blood (OnTLR13b), and the lowest expression levels were observed in the liver (OnTLR13a) and stomach (OnTLR13b). The expression level of OnTLR13b at 5.5 days postfertilization (dpf) was significantly higher than that at the other 8 time points (2.5, 3.5, 4.5, 5, 6, 6.5, 7.5 and 8.5 dpf). Upon stimulation with an intraperitoneal injection of 200 μL (107 CFU/mL) Streptococcus agalactiae , the expression levels of OnTLR13a and OnTLR13b were significantly upregulated in the intestine and gill. After cotransfection with MyD88, OnTLR13a significantly increased MyD88-dependent NF-κB activation in 293 T cells. However, OnTLR13b significantly impaired MyD88-dependent NF-κB activation. In addition, TLR13a slightly increased MyD88-dependent AP-1 activation, and TLR13b significantly increased MyD88-dependent AP-1 activation. TLR13a significantly increased MyD88-dependent interferon-β (IFN-β) activation, and TLR13b had no effect on MyD88-dependent IFN-β activation. These findings suggest that although the deduced protein structure of OnTLR13 is evolutionarily conserved between OnTLR13 and other TLR members, its signal transduction function is markedly different. Co-immunoprecipitation (Co-IP) assays showed that both OnTLR13a and OnTLR13b could interact with OnMyD88. RNA pulldown assays showed that TLR13a and TLR13b could combine with the 23S rRNA of S. agalactiae. These results indicate that TLR13a and TLR13b play important roles in the innate immune response against bacterial infection in Nile tilapia. [ABSTRACT FROM AUTHOR]

A total of 1,000 cultured Nile tilapia (Oreochromis niloticus) were collected from different governmental and private fish farms and examined for detection of myxosporean parasites infection. The infected fishes showed slight unilateral exophthalmia with whitish cyst in the eye. Numerous white cysts like plasmodia of Myxobolus dermatobius were recovered from the eye of the examined fishes with low prevalence rate (1%). Small intact cyst was isolated, fixed in 3% glutaraldehyde in 0.1 M sodium cacodylate (pH 7.4) and prepared for transmission electron microscopy examination. Ultrathin sections myxospores of M. dermatobius revealed pair of capsulogenic cells at the apical pole of the developing myxospore. Single sporoplasm containing a single nucleus and sporoplasmosomes fills nearly all the space beneath the polar capsules. The later were pyriform in shape, each one had homogenous dense core and 4 turns of polar filaments. Ultrastructural characteristics of the present myxospore were described and discussed in detail.

Nile tilapia (Oreochromis niloticus) is among the most important finfish in aquaculture, particularly in Asia. Numerous genetically improved strains of Nile tilapia have been developed and disseminated through formal and informal channels to hatcheries, many of which operate at a relatively small scale in developing countries. The primary objective of this study was to assess the extent to which molecular genetic tools can identify different and interrelated strains of Nile tilapia in Bangladesh and the Philippines, two globally significant producers. A tool was developed using a low-density panel of single-nucleotide polymorphisms (SNPs), genotyping-by-sequencing and discriminant analysis of principal components (DAPC). When applied to 2,057 samples from 205 hatcheries in Bangladesh and the Philippines, for hatcheries where the hatchery-identified strain was one of the sampled core populations used to develop the tool, hatchery-identified and DAPC-assigned hatchery-level strains were in agreement in 74.1% of cases in Bangladesh and 80.6% of cases in the Philippines. The dominant hatchery-identified and DAPC-assigned strains were GIFT, in Bangladesh, and GET-ExCEL—a composite strain partially derived from GIFT—in the Philippines.

As the male reproductive organ, the main task of the testis is the production of fertile, haploid spermatozoa. This process, named spermatogenesis, starts with spermatogonial stem cells, which undergo a species-specific number of mitotic divisions until starting meiosis and further morphological maturation. The pituitary gonadotropins, luteinizing hormone, and follicle stimulating hormone, are indispensable for vertebrate spermatogenesis, but we are still far from fully understanding the complex regulatory networks involved in this process. Therefore, we developed an ex vivo testis cultivation system which allows evaluating the occurring changes in histology and gene expression. The experimental circulatory flow-through setup described in this work provides the possibility to study the function of the male tilapia gonads on a cellular and transcriptional level for at least 7 days. After 1 week of culture, tilapia testis slices kept their structure and all stages of spermatogenesis could be detected histologically. Without pituitary extract (tilPE) however, fibrotic structures appeared, whereas addition of tilPE preserved spermatogenic cysts and somatic interstitium completely. We could show that tilPE has a stimulatory effect on spermatogonia proliferation in our culture system. In the presence of tilPE or hCG, the gene expression of steroidogenesis related genes (cyp11b2 and stAR2) were notably increased. Other testicular genes like piwil1, amh, or dmrt1 were not expressed differentially in the presence or absence of gonadotropins or gonadotropin containing tilPE. We established a suitable system for studying tilapia spermatogenesis ex vivo with promise for future applications.

Classical cadherin gene family relies on calcium ions in playing an important role in adhesion between cells. However, comprehensive studies to identify classical cadherin gene families in Nile tilapia (Oreochromis niloticus) have not been conducted. In this study, 18 classical gene family members were screened from Nile tilapia using various bioinformatics methods. These screened cadherins were randomly scattered across eight different linkage groups and shared a conserved LDRE motif. A phylogenetic tree was constructed to explore the evolution of classical cadherin members. The result showed that all classical cadherins were clustered together to form an independent subfamily. In addition, MEME analysis indicated that almost all the screened cadherins had similar motif arrangements. Also, neural-cadherin has up to eight closely adjacent tandem trisomy motif repeats. Finally, the sequence characteristics of cadherin-1 (Oncdh1) associated with pathogen invasion were discussed. The open reading frame of Oncdh1 was 2052 bp, encoding sequences of 683 amino acids with three conserved domains: cadherin repeat-like domain, cadherin prodomain, and cadherin tandem repeat domain. Real-time PCR experiments were carried out to detect the expression pattern of Oncdh1 in head kidney, brain, intestine, and spleen after Streptococcus agalactiae infection. The results showed a significant induction or downregulation of the expression level of Oncdh1 compared with the control group. Overall, the findings of this study might provide a reference for further research on the function of classical cadherin family of Nile tilapia in the future.

The oral ingestion of collagen hydrolysates (CHs) seems popular nowadays, but there has been little report on the chronological aging of skin so far. A CHs (average molecular weight = 624.72 Da) was prepared from the skin of Nile tilapia by simulated gastrointestinal digestion in this study. It exhibited high yield (97.04%), digestibility (98.12%) and antioxidant activity towards 1,1-diphenyl-2-picrylhydrazyl radical (half maximal inhibitory concentration, IC50 = 2.57 mg/mL) and linoleic acid peroxidation (IC50 = 0.36 mg/mL). The safety (4.07 g/kg bw·d) was also confirmed through the feeding of 9-month-old mice for 180 days. More importantly, the visual appearance, histological structure and matrix homeostasis of mice skin were remarkably improved. Furthermore, oxidative stress was alleviated by enhancing the activities of antioxidant enzymes, which was an important reason for the improvement of skin properties. These suggested its potential to be exploited into new functional foods with the effect against chronological aging of skin.

Nile tilapia (Oreochromis niloticus) is among the most important finfish in aquaculture, particularly in Asia. Numerous genetically improved strains of Nile tilapia have been developed and disseminated through formal and informal channels to hatcheries, many of which operate at a relatively small scale in developing countries. The primary objective of this study was to assess the extent to which molecular genetic tools can identify different and interrelated strains of Nile tilapia in Bangladesh and the Philippines, two globally significant producers. A tool was developed using a low-density panel of single-nucleotide polymorphisms (SNPs), genotyping-by-sequencing and discriminant analysis of principal components (DAPC). When applied to 2,057 samples from 205 hatcheries in Bangladesh and the Philippines, for hatcheries where the hatchery-identified strain was one of the sampled core populations used to develop the tool, hatchery-identified and DAPC-assigned hatchery-level strains were in agreement in 74.1% of cases in Bangladesh and 80.6% of cases in the Philippines. The dominant hatchery-identified and DAPC-assigned strains were GIFT, in Bangladesh, and GET-ExCEL—a composite strain partially derived from GIFT—in the Philippines. [ABSTRACT FROM AUTHOR]

The remediation of wastewater (WW) is a promising solution for limited water sources. This study aimed to evaluate rice straw (RS) and zeolite (Z) as bioadsorbents for the removal of pollutants, including heavy metals (HMs) (cadmium [Cd], nickel [Ni], and lead [Pb]) and malathion (PC), from WW and to assess the suitability of reusing remediated WW in fish rearing units. A total of 11 treatment groups with 3 replicates each were designed with different combinations of RS and/or Z for the treatment of real WW contaminated with HMs and malathion, where the WW remained in contact with the adsorbents for 24 h. Different remediated WWs were used for rearing Nile tilapia (Oreochromis niloticus), which were randomly allocated into 33 glass aquaria representing 11 treatments with 3 replicates each for 30 days. The best remediation efficiency was achieved using a mixture of whole RS (WRS), chopped RS (CRS), and Z (HM-PC-WRS-CRS-Z group), with removal percentages of 92%, 95%, 96%, and 99% for Cd, Ni, Pb, and malathion, respectively. The health status of the aquatic ecosystems was assessed through blood tests to characterize biochemical parameters and through pathological changes of cultured O. niloticus reared in treated WW. A significant (P ˂ 0.05) effect on the blood biochemistry of fish reared in treated WW was found and better biochemical and histologic architecture was observed than that of fish reared in untreated WW. A novel mixture of WRS, CRS, and Z could possibly be a promising low-cost adsorbent for wastewater treatment. [ABSTRACT FROM AUTHOR]

Chemokines are a class of small molecular weight cytokines of 6–14 kDa, exerting important roles in the regulation of various inflammatory diseases and immune cell migration. In this study, we have identified the CXCL12 gene from Nile tilapia (Oreochromis niloticus), including CXCL12a (OnCXCL12a) and CXCL12b (OnCXCL12b). The open reading frames of OnCXCL12a and OnCXCL12b are 309 and 297 bp, encoding 102 and 98 amino acids, respectively. Multiple alignment showed that OnCXCL12a and OnCXCL12b have characteristics of CXC chemokines and share high identity with CXCL12 amino acid sequences from the known species. Tissue distribution in the healthy fish indicated that OnCXCL12a and OnCXCL12b expressed in all examined tissues, with the highest expression in muscle and anterior kidney, respectively. After challenged by Streptococcus agalactiae , Poly(I:C) and LPS in vivo and in vitro , OnCXCL12 is transcriptionally up-regulated in immune tissues and cells significantly. The recombinant OnCXCL12 proteins, (r)OnCXCL12a and (r)OnCXCL12b, enhance the release of nitric oxide and increase the expression of inflammatory cytokines (TNF-α, IL-6, and IL-10) in anterior kidney leukocytes, as well as exhibit chemotactic activity for leukocytes from anterior kidney. Summarizing, these results indicate that OnCXCL12 is involved in the immune response of Nile tilapia against pathogen infection and may play an important role in mediating inflammatory response. • The CXCL12a and CXCL12b (OnCXCL12a and OnCXCL12b) genes were identified in Nile tilapia. • OnCXCL12a and OnCXCL12b expressed in different tissues widely, and high in immune tissues. • OnCXCL12a and OnCXCL12b were significantly up-regulated upon Poly(I:C), Streptococcus agalactiae and LPS challenge. • OnCXCL12a and OnCXCL12b got involved in the inflammatory response. [ABSTRACT FROM AUTHOR]

As the male reproductive organ, the main task of the testis is the production of fertile, haploid spermatozoa. This process, named spermatogenesis, starts with spermatogonial stem cells, which undergo a species-specific number of mitotic divisions until starting meiosis and further morphological maturation. The pituitary gonadotropins, luteinizing hormone, and follicle stimulating hormone, are indispensable for vertebrate spermatogenesis, but we are still far from fully understanding the complex regulatory networks involved in this process. Therefore, we developed an ex vivo testis cultivation system which allows evaluating the occurring changes in histology and gene expression. The experimental circulatory flow-through setup described in this work provides the possibility to study the function of the male tilapia gonads on a cellular and transcriptional level for at least 7 days. After 1 week of culture, tilapia testis slices kept their structure and all stages of spermatogenesis could be detected histologically. Without pituitary extract (tilPE) however, fibrotic structures appeared, whereas addition of tilPE preserved spermatogenic cysts and somatic interstitium completely. We could show that tilPE has a stimulatory effect on spermatogonia proliferation in our culture system. In the presence of tilPE or hCG, the gene expression of steroidogenesis related genes (cyp11b2 and stAR2) were notably increased. Other testicular genes like piwil1, amh , or dmrt1 were not expressed differentially in the presence or absence of gonadotropins or gonadotropin containing tilPE. We established a suitable system for studying tilapia spermatogenesis ex vivo with promise for future applications. [ABSTRACT FROM AUTHOR]

As one important member of the two-pore-domain potassium channel (K 2P) family, potassium channel subfamily K member 3 (KCNK3) has been reported for thermogenesis regulation, energy homeostasis, membrane potential conduction, and pulmonary hypertension in mammals. However, its roles in fishes are far less examined and published. In the present study, we identified two kcnk3 genes (kcnk3a and kcnk3b) in an euryhaline fish, Nile tilapia (Oreochromis niloticus), by molecular cloning, genomic survey and laboratory experiments to investigate their potential roles for osmoregulation. We obtained full-length coding sequences of the kcnk3a and kcnk3b genes (1209 and 1173 bp), which encode 402 and 390 amino acids, respectively. Subsequent multiple sequence alignments, putative 3D-structure model prediction, genomic survey and phylogenetic analysis confirmed that two kcnk3 paralogs are widely presented in fish genomes. Interestingly, a DNA fragment inversion of a kcnk3a cluster was found in Cypriniforme in comparison with other fishes. Quantitative real-time PCRs demonstrated that both the tilapia kcnk3 genes were detected in all the examined tissues with a similar distribution pattern, and the highest transcriptions were observed in the heart. Meanwhile, both kcnk3 genes in the gill were proved to have a similar transcriptional change pattern in response to various salinity of seawater, implying that they might be involved in osmoregulation. Furthermore, three predicted transcription factors (arid3a , arid3b , and arid5a) of both kcnk3 genes also showed a similar pattern as their target genes in response to the various salinity, suggesting their potential positive regulatory roles. In summary, we for the first time characterized the two kcnk3 genes in Nile tilapia, and demonstrated their potential involvement in osmoregulation for this economically important fish. • Two kcnk3 genes (kcnk3a and kcnk3b) were identified from Nile tilapia by molecular cloning. • Both kcnk3 genes are highly conserved among vertebrates including fishes. • A special kcnk3a cluster reversal was found in Cypriniformes fishes by a genomic survey. • Tilapia kcnk3a and kcnk3b genes showed a similar tissue distribution pattern, with the highest transcription in heart. • Both two kcnk3 genes are involved in osmoregulation roles in Nile tilapia. [ABSTRACT FROM AUTHOR]

he present experiment was conducted to determine the optimal source and level of phosphorus supplementation in commercial feeds with the highest growth rate and the lowest releasing in environmental and protect water quality of Nile Juveniles tilapia (Oreochromis niloticus). Fish were divided into twelve groups (groups) each group was stocked into two aquaria each contains 10 fish. Fish were fed diet contained different levels of phosphorus (0.005, 0.007, 0.009 and 0.011%Kg diet phosphorus) from three different sources of phosphorus (mono calcium phosphate, mono potassium phosphate and mono sodium phosphate) for a period of 12 weeks. Results showed that average daily gain, specific growth rate, protein efficiency ratio and feed conversation ratio were significantly improved at (p) 1.1% dietary phosphorus level with mono sodium phosphate as the source of phosphorus, mono calcium phosphate represented the highest significant (P

Competitive interactions not only exist between invasive and native fish species but also between different invasive species, especially between those that have broad niche overlap. Nile tilapia (Oreochromis niloticus) and Redbelly tilapia (Tilapia zillii) are the most common invasive tilapia species in the rivers of South China. There may be specific factors that influence their competitive interactions and disturbance patterns, and temperature has been considered the most important factor. To study how temperature affects the distribution patterns and competitive interactions of these two invasive tilapia species, field surveys and laboratory experiments were conducted. Field surveys showed that latitude affected the ratio but not the biomass of all tilapia species. Nile tilapia was more abundant in the southern (warmer) sites, and Redbelly tilapia was more abundant in the northern (colder) sites. The distribution patterns of the two tilapia species were also related to latitude and minimum winter temperature. The results of the laboratory-based temperature experiments further confirmed that Redbelly tilapia can tolerate lower temperatures than Nile tilapia. However, the Nile tilapia were larger in field surveys, and laboratory experiments also showed that Nile tilapia are stronger competitors in warmer water because of their larger body size. Therefore, we suggest that the distribution patterns of these two invasive tilapia species were related to temperature conditions.

Black pomfret and nile tilapia are belonging to order Perciformes. Both fish are live in different habitat. Black pomfret is marine water whereas nile tilapia is in freshwater. The purpose of the study was to determine anatomy and histology of the kidneys structures in both fishes. Histological preparations were done using paraffin method, with Hematoxylin-Eosin (HE) staining. The results, showed that Black pomfret and nile tilapia have y-shape kidney. Nile tilapia has darker red colour and softer texture than black pomfret kidney. Histologically, black pomfret and nile tilapia kidneys have a distal tubule, proximal tubule, glomerulus and lymphoid tissue. Glomerular diameter of nile tilapia (69,22 µm) was larger than pomfret (61,25 µm). It can be concluded that differences between anatomical and histological structure of kidney are affected by habitat differences.

With the development of aquaculture industry, high-carbohydrate diet is used to stimulate protein-sparing effect and reduce feed cost. However, fish utilize carbohydrates poorly in general, and instead, high level of carbohydrates in the diet influence the growth condition of fish. How to alleviate the side effects of high carbohydrate diet on fish health has attracted more and more attentions. In the present study, Nile tilapia (Oreochromis niloticus) were fed with 25% and 45% of carbohydrate diet for eight weeks. Higher body weight but lower resistance to pathogen was found in 45% carbohydrate diet group. Higher expression level of inflammation cytokines, increased expression of total NF-κB protein and phosphorylated NF-κB protein (p-NF-κB) were detected in higher carbohydrate group. Concentration of short-chain fatty acids (SCFAs) was measured and the results indicated that high-carbohydrate diet decreased acetate content in the intestine. In order to detect the relationship between the decreased concentration of acetate and lower resistance to pathogen in high-carbohydrate group, 45% of carbohydrate diets (HC) supplemented with different concentrations of sodium acetate (HC + LA, 100 mmol/L; HC + MA, 200 mmol/L; HC + HA, 400 mmol/L) were used to raise Nile Tilapia for eight weeks. The results indicated that addition of 200 mmol/L sodium acetate (HC + MA) reduced the mortality when fish were challenged with Aeromonas hydrophila. Furthermore, we also found that addition of 200 mmol/L sodium acetate mainly inhibited p38 mitogen-activated protein kinase (p38MAPK) and NF-κB phosphorylation to decrease the expression level of inflammation cytokines (IL-8, IL-12, TNF-α and IL-1β) in the intestine. The present study indicated that certain concentration of sodium acetate could alleviate high-carbohydrate induced intestinal inflammation mainly by suppressing MAPK activation and NF-κB phosphorylation. Image 1 • High-carbohydrate diet increased weight while decreased resistance to pathogen. • High-carbohydrate diet reduced acetate content and induced intestinal inflammation. • Addition of sodium acetate in high-carbohydrate increased resistance to pathogen. • Addition of sodium acetate in high-carbohydrate alleviated intestinal inflammation. • Sodium acetate suppressed MAPK and NF-κB signaling pathways of intestine. [ABSTRACT FROM AUTHOR]

Interleukin-1 receptor-associated kinase 1 (IRAK1) and IRAK4 are critical signalling mediators and play pivotal roles in the innate immune and inflammatory responses mediated by TLR/IL-1R. In the present study, two IRAK family members, On IRAK1 and On IRAK4, were identified in the Nile tilapia Oreochromis niloticus with a conserved N-terminal death domain and a protein kinase domain, similar to those of other fishes and mammals. The gene structures of On IRAK1 and On IRAK4 are organized into fifteen exons split by fourteen introns and ten exons split by nine introns. On IRAK1 and On IRAK4 were broadly expressed in all of the tissues tested, with the highest expression levels being observed in the blood and the lowest expression levels being observed in the liver. Both genes could be detected from 2 d post-fertilization (dpf) to 8 dpf during embryonic development. Moreover, the expression levels of On IRAK1 and On IRAK4 were clearly altered in all five tissues after Streptococcus agalactiae infection in vivo and could be induced by LPS, Poly I: C, S. agalactiae WC1535 and △CPS in Nile tilapia macrophages. The overexpression of On IRAK1 and On IRAK4 in 293T cells showed that they were both distributed in the cytoplasm and could significantly increase NF-κB activation. Interestingly, after transfection, On IRAK1 significantly upregulated On Myd88-induced NF-κB activation, while On IRAK4 had no effect on On Myd88-induced NF-κB activation. Co-immunoprecipitation (Co-IP) assays showed that On Myd88 did not interact with either On IRAK1 or On IRAK4 and that On IRAK1 did not interact with On IRAK4. Taken together, these findings suggest that On IRAK1 and On IRAK4 could play important roles in TLR/IL-1R signalling pathways and the immune response to pathogen invasion. • On IRAK1 and On IRAK4 gene were identified in Nile tilapia and were upregulated after S. agalactiae challenge. • On IRAK1 and On IRAK4 induced by LPS, Poly I: C, wild and mutant type S. agalactiae in in vitro. • On Myd88 did not interact with either On IRAK1 or On IRAK4, and On IRAK1 did not interact with On IRAK4. • Overexpression of On IRAK1 and On IRAK4 significantly increased NF-κB activation. • On IRAK1 significantly upregulated the NF-κB activity induced by On Myd88. [ABSTRACT FROM AUTHOR]

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The MAPK pathway is the common intersection of signal transduction pathways such as inflammation, differentiation and proliferation and plays an important role in the process of antiviral immunity. Streptococcus agalactiae will have a great impact on tilapia aquaculture, so it is necessary to study the immune response mechanism of tilapia to S. agalactiae. In this study, we isolated the cDNA sequences of TAK1 , TAB1 and TAB2 from Nile tilapia (Oreochromis niloticus). The TAK1 gene was 3492 bp in length, contained an open reading frame (ORF) of 1809 bp and encoded a polypeptide of 602 amino acids. The cDNA sequence of the TAB1 gene was 4001 bp, and its ORF was 1491 bp, which encoded 497 amino acids. The cDNA sequence of the TAB2 gene was 4792 bp, and its ORF was 2217 bp, encoding 738 amino acids. TAK1 has an S_TKc domain and a coiled coil structure; the TAB1 protein structure contains a PP2C_SIG domain and a conserved PYVDXA/TXF sequence model; and TAB2 contains a CUE domain, a coiled coil domain and a Znf_RBZ domain. Homology analysis showed that TAK1 and TAB1 had the highest homology with Neolamprologus brichardi , and TAB2 had the highest homology with Simochromis diagramma (98.28 %). In the phylogenetic tree, TAK1, TAB1 and TAB2 formed a large branch with other scleractinian fishes. The tissue expression analysis showed that the expression of TAK1 , TAB1 and TAB2 was highest in the muscle. The expression of TAK1 , TAB1 and TAB2 was significantly induced in most of the tested tissues after stimulation with LPS, Poly I:C and S. agalactiae. The subcellular localization results showed that TAK1 was located in the cytoplasm, and TAB1 and TAB2 had certain distributions in the cytoplasm and nucleus. Coimmunoprecipitation (Co-IP) results showed that TRAF6 did not interact with the TAK1 protein but interacted with TAB2, while TAB1 did not interact with P38γ but interacted with TAK1. There was also an interaction between TAK1 and TAB2. • The cDNA sequences of TAK1, TAB1, and TAB2 were identified from tilapia (Oreochromis niloticus). • Stimulation with S. agalactiae , PolyI:C and LPS can change the gene expression levels of AK1, TAB1, and TAB2. • TAK1 was mainly present in the cytoplasm of tilapia. The TAB1 and TAB2 genes were distributed in both the nucleus and cytoplasm. • TRAF6 did not interact with the TAK1 protein but interacted with TAB2. • TAB1 did not interact with P38γ but interacted with TAK1. • There was also an interaction between TAK1 and TAB2. [ABSTRACT FROM AUTHOR]

Abstract A 12-week feeding trial was conducted to evaluate the effect of different ratios of fish meal (FM): cotton seed meal (CSM) without or with inclusion of exogenous protease in diets on growth performance, hematology, digestibility and selected gene expression markers (GH and I (IGF-I) of juvenile Nile tilapia. The experimental diets were categorized into three groups; the first group CSM 1 which contained fish meal protein: cotton seed meal protein (FM: CSM = 2:1), the second group CSM 2 which contained FM: CSM = 1:1 and the third one CSM 3 contained FM: CSM = 1:2 on protein content based. All groups were supplemented with exogenous protease at 0 and 2500 U kg−1 diet, respectively. All diets were fed to fish (initial body weight 11.62 ± 0.03 g fish−1) in triplicate aquaria twice daily. The higher weight gain (WG), protein efficiency ratio (PER) and best feed conversion ratio (FCR) were recorded by fish fed CSM 1 and CSM 2 and supplemented with 2500 U protease/kg diet. The highest apparent digestibility coefficient of crude protein, crude lipid and digestible energy, and apparent availability coefficient of essential amino acids were obtained by fish receiving CSM 1 and CSM 2 supplemented with protease (2500 U protease kg−1 diet). The highest mean values of Hb, Htc and RBCs were recorded in fish fed CSM 1 and CSM 2 supplemented with protease enzyme (2500 U protease kg−1 diet). Serum of alanine and aspartate aminotransferase activities were improved due to dietary protease (2500 U protease kg−1 diet) supplementation, also, fish received the diets supplemented with protease 2500 U kg−1 diet generally had higher total protein, albumin, calcium and phosphorus than those fed diets without supplement. The highest growth hormone (GH) gene expression in brain and liver of tilapia were obtained in the group fed CSM 3 and un-supplemented with protease enzyme followed by CSM 2 (un-supplemented). On the other hand, tilapia fed CSM 1 and CSM 2 supplemented with protease enzyme showed the highest values of gene expression of insulin like growth factor I (IGF-I) in brain and liver of tilapia compared to other groups. Results above showed that supplementation of protease can improve growth, nutrient assimilation, and hematology and alter gene expression of GH and IGF-I of Nile tilapia. Highlights • Exogenous protease improved the nutritional values of cotton seed meal. • Exogenous protease increased the growth performance and feed utilization of tilapia fed cotton seed meal. • Exogenous protease improved the physiological indices of tilapia fed cotton seed meal. [ABSTRACT FROM AUTHOR]

Competitive interactions not only exist between invasive and native fish species but also between different invasive species, especially between those that have broad niche overlap. Nile tilapia (Oreochromis niloticus) and Redbelly tilapia (Tilapia zillii) are the most common invasive tilapia species in the rivers of South China. There may be specific factors that influence their competitive interactions and disturbance patterns, and temperature has been considered the most important factor. To study how temperature affects the distribution patterns and competitive interactions of these two invasive tilapia species, field surveys and laboratory experiments were conducted. Field surveys showed that latitude affected the ratio but not the biomass of all tilapia species. Nile tilapia was more abundant in the southern (warmer) sites, and Redbelly tilapia was more abundant in the northern (colder) sites. The distribution patterns of the two tilapia species were also related to latitude and minimum winter temperature. The results of the laboratory-based temperature experiments further confirmed that Redbelly tilapia can tolerate lower temperatures than Nile tilapia. However, the Nile tilapia were larger in field surveys, and laboratory experiments also showed that Nile tilapia are stronger competitors in warmer water because of their larger body size. Therefore, we suggest that the distribution patterns of these two invasive tilapia species were related to temperature conditions. [ABSTRACT FROM AUTHOR]