Infection dynamics of Shewanella spp. in Nile tilapia under varied water temperatures: A hematological, biochemical, antioxidant-immune analysis, and histopathological alterations.

In aquaculture, fluctuating water temperatures can act as a potent stressor, influencing the virulence and transmission dynamics of pathogenic bacteria, potentially triggering outbreaks and impacting fish health. The purpose of this work was to examine the impact of Shewanella spp. infection on hematological, biochemical, and antioxidant-immune parameters of Nile tilapia (Oreochromis niloticus) under different water temperatures. For this purpose, 180 fish were divided into 6 groups in triplicate (30 fish per group; 10 fish per replicate). Group 1 (G1), G2, and G3 were reared at varying water temperatures (22 °C, 28 °C, and 31 °C, respectively) without infection. While G4, G5, and G6 were IP-injected with 0.2 mL of Shewanella spp. (0.14 × 105) and reared at 22 °C, 28 °C, and 31 °C, respectively. Shewanella spp. infection induced significant lowering (p < 0.05) in hematological parameters (red and white blood cells, hemoglobin, and packed cell volume%) and immune-antioxidant responses (phagocytic activity%, phagocytic index, lysozyme, nitric oxide), total antioxidant capacity, catalase, and reduced glutathione, especially at 22 °C. Moreover, a significant increase (p < 0.05) in the hepato-renal function indicators (alanine aminotransferase, aspartate aminotransferase, urea, and creatinine), stress biomarkers (glucose and cortisol), malondialdehyde, and pro-inflammatory cytokines (interleukin-1ß and tumor necrosis factor-α) were the consequences of the Shewanella spp. infection, especially at 22 °C. The Shewanella spp. infection exhibited marked histopathological changes in the hepatic and renal tissues. Worthily, Shewanella spp. can cause detrimental alterations in Nile tilapia's hematological, biochemical, and antioxidant-immune parameters at various water temperatures, but the major detrimental changes were observed at a water temperature of 22 °C. Consequently, we can conclude that the infection dynamics of Shewanella spp. are exaggerated at 22 °C. These outcomes could help in understanding the nature of such an infection in Nile tilapia.

The contribution of Coriandrum sativum in enhancing Oreochromis niloticus rearing at sub-optimal temperatures: effect on growth, health status, survival rate, and resistance to Aeromons Veronii.

This study (60 days) was conducted to investigate the ability of diet enriched with Coriandrum sativum powder or its extract to protect Oreochromis niloticus health and survivability at suboptimal temperature (21 ℃). One hundred and twenty (33.14 ± 0.5 g) were divided into four groups; each group has three replicates.. The first control group fed on a basal diet. Second and third groups fed on diet enriched with 30 mg/kg coriander seed powder (CP) and coriander seed ethanolic extract (CE), respectively. The fourth group (OT) fed on diet enriched with 500 mg oxytetracycline/kg diet. The results revealed that CE exhibited a considerable improvement in hematological parameters, hepatic-renal functions, antioxidant status, and immunological markers as well as remarkably increased resistance against Aeromonas veronii. It could be concluded that feeding tilapia CE enriched diet at 30 mg/kg is a recommended strategy to enhance tilapia health and resistance to A. veronii infection reared at 21 ℃.

Therapeutic efficacy of coriander (Coriandrum sativum) enriched diets in Oreochromis niloticus: effect on hepatic-renal functions, the antioxidant-immune response and resistance to Aeromonas veronii.

In this study, the effects of Coriandrum sativum to control Aeromonas veronii infection in Oreochromis niloticus were determined. Coriandrum sativum extract (CE) was tested in vitro against A. veronii by the disc diffusion assay. In in vivo, 150 O. niloticus (from El-Abbassa, Sharkia, Egypt, weighing 34.95 ± 1.98 g) was distributed in five groups (with three replications) in glass aquariums (80 × 40 × 30 cm). The first group (control) was intraperitoneally injected with 0.2 ml of sterilized tryptic soya broth. Groups 2-5 were intraperitoneally challenged with 0.2 ml of A. veronii (4.3 × 106). The five groups were administered a basal diet until clinical signs appeared, and then therapeutic feeding (15 days) was followed: the first (CONT) and second (AV) groups were administered a normal basal diet. The third (AV+CP) and fourth (AV+CE) groups were administered diets supplemented with C. sativum powder and extract, respectively, each at 30 mg/kg. The fifth group (AV+OT) was administered a diet supplemented with oxytetracycline at 500 mg/kg diet. The results of the in vitro experiment revealed that CE has a zone of inhibition of 43 mm against A. veronii. The in vivo results showed that fish administered a therapeutic diet supplemented with CE showed a significant improvement in hematological, biochemical, and immunological parameters, as well as antioxidant capacity (P < 0.05) and the pathological findings of the liver and kidney tissues. The current findings supported that the administration of a CE-enriched diet (30 mg/kg) is an eco-friendly strategy for controlling A. veronii in O. niloticus.

The potential effect of Moringa oleifera ethanolic leaf extract against oxidative stress, immune response disruption induced by abamectin exposure in Oreochromis niloticus.

Abamectin (ABM), a naturally fermented product of Streptomyces avermitilis, is applied to pest control in livestock and agriculture fields. The aim of the current study is to evaluate the protective effects of Moringa oleifera leaf ethanolic extract (MOE) on biochemical changes including oxidative stress indices, immune response marker, lipid profiles as well as mRNA expression of immune related genes, and abamectin (ABM, 5% EC) residue levels in Nile tilapia (Oreochromis niloticus) exposed to a sub-lethal concentration (0.5 µg/l) for 28 days. Disturbance in liver and kidney biomarkers was markedly increased in ABM-exposed fish compared to the control group. Malondialdehyde levels in the liver and brain tissues, as well as the activities of glutathione-s-transferase, superoxide dismutase, and glutathione peroxides, all increased significantly in ABM group. Additionally, ABM exposure increased the levels of interleukin 10 beta and growth factor gene expression. On the other hand, fish exposed to ABM had significantly lower serum alkaline phosphatase, creatinine, high-density lipoprotein, glutathione peroxides in brain, glutathione in liver and brain tissues, lysozyme activity, nitric oxide, immunoglobulin M, tumor necrosis factor, and interleukin 1 beta as compared to the control group. The recorded detrimental effects of ABM on tilapia have been overcome by the addition of MOE to the diet (1%) and ameliorating hepato-renal damage and enhancing antioxidant activity, innate immune responses, and upregulating the anti-inflammatory gene expression. Therefore, it could be concluded that MOE dietary supplementation at 1% could be used to counteract the oxidative stress, immune response disruption induced by abamectin exposure in Oreochromis niloticus, and reduce its accumulation in fish tissues.

Zinc Oxide Nanoparticles (ZnO-NPs) Suppress Fertility by Activating Autophagy, Apoptosis, and Oxidative Stress in the Developing Oocytes of Female Zebrafish.

In vertebrates, the core mechanisms that control gametogenesis are largely multiple, complex, successive, and orchestrated by intrinsic and extrinsic factors. However, age, health status, and hormonal activity are important factors for good fertility; other intangible intracellular molecular mechanisms that manage oocyte development are still unclear. The present study was designed to elucidate the ultrastructure changes in the ovary in response to its exposure to zinc oxide nanoparticles (ZnO-NPs) and to explore the role of autophagy and apoptosis during egg maturation and ovulation on the fertility of female zebrafish. In our study, ZnO-NPs could induce cytotoxicity in the maturing oocyte by activating autophagy and apoptosis in a caspase-dependent manner and could induce oxidative stress by generating reactive oxygen species (ROS) that elevated the mutated ovarian tP53 protein. Simultaneously, necroptosis developed, mimicking the features of apoptosis and necrosis. Collectively, ZnO-NPs created a suitable necrotic environment that led to follicular developmental retardation that altered oocyte ovulation and reduced fecundity of female zebrafish.

Corrigendum to "Assessment the using of silica nanoparticles (SiO2NPs) biosynthesized from rice husks by Trichoderma harzianum MZ066609 as water lead adsorbent for immune status of Nile tilapia (Oreochromis niloticus)" [Saudi J. Biol. Sci. 28(9) (2021) 5119-5130].

[This corrects the article DOI: 10.1016/j.sjbs.2021.05.027.].

Rice protein concentrate as a fish meal substitute in Oreochromis niloticus: Effects on immune response, intestinal cytokines, Aeromonas veronii resistance, and gut microbiota composition.

The potential of rice protein concentrate (RPC) to substitute fishmeal (FM) protein in the diet of Oreochromis niloticus was assessed in a five-month-long feeding trial. Fishmeal protein was replaced by RPC at rates of 0% (control), 25%, 50%, and 75% (RPC0, RPC25, RPC50, and RPC75, respectively). RPC25 had no significant effect on antioxidant capacity (total antioxidant capacity; superoxide dismutase, catalase, and glutathione peroxidase activities) and immune indices (lysozyme, nitric oxide, antiprotease, and bactericidal activities) after one, two, and five months of feeding, while the values for these parameters were significantly lower in the RPC75 group compared to those in the RPC0 group. The RPC25 group showed higher mRNA levels of the intestinal cytokines IL-1ß, IL-10ß, TGF-ß, and TNF-α than the control group. In fish affected by Aeromonas veronii, the highest significant cumulative mortality was recorded in the RPC75 group, followed by the RPC50, RPC25, and control groups. Gut microbiome analyses showed a reduction in microbial diversity in response to the addition of RPC, regardless of the RPC content, and the composition of the community of the RPC samples differed from that of the control. RPC-enriched diets resulted in higher relative abundances of Bacteroidetes and Fusobacteria in the gut compared to that in the gut of the control fish. In summary, RPC can be used to replace up to 25% of the FM protein in the diet of O. niloticus, while improving the antioxidant capacity, immunocompetence, and disease resistance of the fish.

Assessment the using of silica nanoparticles (SiO2NPs) biosynthesized from rice husks by Trichoderma harzianum MF780864 as water lead adsorbent for immune status of Nile tilapia (Oreochromis niloticus).

Rice husks (RHs) was used as a substrate for biosynthesis of high-value Silica nanoparticles (SiO2NPs). An isolate of Trichoderma harzianum MF780864 (T. harzianum) was isolated and identified based on the Internal Transcribed Spacers (ITS) sequences; it showed the potentiality to induce SiO2NPs in the process of RHs biotransformation. SiO2NPs were produced extracellularly and their size was of about 89 nm. SiO2NPs characterized by oval, rod and cubical particles by using Transmission Electron Microscope (TEM).The Fourier transform infrared spectroscopy (FTIR) confirmed the presence of various functional groups of biomolecules and capping protein, encapsulating SiO2NPs. Water and fish samples were collected from private fish farms in El-Sharkia Governorate, Egypt. Lead (Pb) was detected from water and fish samples at its highest concentration at about 0.088 mg/L. The adsorption capacity of Pb by SiO2NPs was evaluated by testing different concentrations of SiO2NPs viz. 1, 2, and 3 mg/L, wherein 1 mg/L revealed the highest Pb adsorption efficiency. Within laboratory trials, the results indicated that highest Pb adsorption efficiency revealed through the increasing of SiO2NPs concentrations until 120 h. In vivo trial that lasted for 8 weeks, Nile tilapia (Oreochromis niloticus) (29.78 ± 0.36 g body weight) supplemented with 0.088 mg/L Pb was divided into four experimental groups having three replicates (15 fish/replicate; 45 fish/group). The results showed that SiO2NPs supplementation through water revealed significant increase in growth and hematological parameters of O. niloticus. Moreover, enhancement of antioxidant capacity (TAC), and immune related gene expression of IL-1ß were increased in the presence of SiO2NPs compared with the groups of Pb exposure. Moreover, Pb residue level in fish muscles was noticeably decreased in the SiO2NPs treated groups. Thus, this research opens up other possibilities in the field of using SiO2NPs as a lead adsorbent for water bioremediation.

Immunological Responses and the Antioxidant Status in African Catfish (Clarias gariepinus) Following Replacement of Dietary Fish Meal with Plant Protein.

African catfish (Clarias gariepinus) were subjected to a 30-day feeding trial to determine the appropriateness of using plant protein (PP) (soybean and sunflower meal) as a fishmeal (FM) replacement in the diet and its effects on immune status, antioxidant activity, pituitary adenylate cyclase-activating polypeptide (PACAP) gene expression, and disease resistance. A total of 150 C. gariepinus (51.01 ± 0.34 g) were randomly distributed among five groups in triplicate. Five experimental diets were formulated to replace 0 (control), 33.5, 50, 66.5, and 100% FM with soybean and sunflower meal to form the experimental diets (R0, R33.5, R50, R66.5, and R100, respectively). After 30 days, the diet containing PP for FM had no significant impact on total, and differential leukocyte counts determined at the end of the feeding period. The total globulin concentration showed significantly greater differences in the following order R0 > R33.5 > R50 > R66.5 > R100. The R0 group had the highest concentration of serum γ-globulin, while R100 had the lowest concentration. The antioxidant status complements 3 (C3), lysozyme activity (LYZ), and antiprotease activity were not significantly different between R0, R33.5, and R50 groups, while they were significantly lower in R100. The serum nitric oxide activity (NO) exhibited significantly greater differences in the following order R0 > R33.5 > R50 > R66.5 > R100. PACAP was significantly higher in the R33.5 group. The highest cumulative mortality caused by Aeromonas sobria was recorded in the R100 group (60%) and the lowest in the R0 group (30%). In conclusion, the results indicate that the immunological responses and antioxidant status of C. gariepinus were not affected when they consumed a diet with FM replaced by up to 50% with PP (SBM and SFM) with methionine and lysine supplementation, but total globulin, NO, and cumulative mortality were impaired with a diet containing a 100% FM replacement.

Growth, Hemato-Biochemical Parameters, Body Composition, and Myostatin Gene Expression of Clarias gariepinus Fed by Replacing Fishmeal with Plant Protein.

In this study, we evaluated the consequences of replacement of fishmeal with plant protein sources (soybean and sunflower meal) on fish growth parameters, haemato-biochemical factors, body composition, and myostatin gene expression of Clarias gariepinus. A total of 150 C. gariepinus were organized in glass aquaria into five investigational groups, with each group in triplicate (30 fish/group; 10 fish/replicate). Group 1 was fed a control diet (15% fishmeal). The other groups were fed diets where fishmeal was replaced gradually with plant protein, with 10% fishmeal in the second group (D1), 7.5% fishmeal in the third group (D2), 5% fishmeal in the fourth group (D3), and 0% fishmeal in the fifth group (D4). There were no significant differences regarding growth performances and body composition among the groups, except that the feed conversion ratio was improved in D4. The different diet types did not affect hematologic parameters and blood indices. Serum growth hormone and amylase levels also revealed no significant (p = 0.09 and 0.55, respectively) differences among the groups, while serum lipase levels decreased significantly (p = 0.000) due to partial (D2) or complete (D4) substitution of fishmeal with plant protein. The replacement of fishmeal had no effects on liver (p = 0.51) and kidney functions (p = 0.34). However, D4 showed the best profit and economic efficiency compared to the other groups. Altogether, we concluded that substitution of fishmeal with plant protein sources is economically beneficial and may be without any adverse effects on growth parameters, body composition, or hematologic and biochemical parameters, but with the addition of synthetic amino acids.

Dietary exposure to methyl mercury chloride induces alterations in hematology, biochemical parameters, and mRNA expression of antioxidant enzymes and metallothionein in Nile tilapia.

Methyl mercury chloride "MMC" (CH3ClHg) is an ubiquitous environmental toxicant that causes a variety of adverse effects. In the present study, we investigated the effects of sub-chronic toxicity of MMC on Nile tilapia (Oreochromis niloticus) through the evaluation of growth performance and hematological, biochemical, and oxidative stress biomarkers. From 150 healthy fish, five equally sized treatment groups were created: a control (CT) group fed with a basal diet and four MMC treatment groups exposed to 0.5, 1, 1.5, and 2 mg of MMC per kg of basal diet for 60 days. MMC exposure significantly reduced the growth performance and survival of O. niloticus and decreased red blood cell count and hemoglobin concentration. Treated fish exhibited normocytic normochromic anemia in addition to leucopenia, lymphopenia, granulocytopenia, and monocytopenia. Moreover, MMC exposure significantly affected liver function, including a reduction in the total protein levels while increasing cholesterol and triglyceride levels. It also markedly increased the production of stress biomarkers such as glucose and cortisol levels. Furthermore, MMC significantly elevated the levels of hepatic enzymes, induced tissue damage, and caused inflammation, as indicated by the upregulation of mRNA expression of hepatic metallothionein. Finally, MMC exposure induced oxidative stress by altering the antioxidant status of the liver and downregulating the mRNA expression of superoxide dismutase, glutathione peroxidase, and glutathione S-reductase. In conclusion, MMC toxicity induced hematological and biochemical alterations, leading to an enhanced state of oxidative stress in O. niloticus.

Bioremediation effect of pomegranate peel on subchronic mercury immunotoxicity on African catfish (Clarias gariepinus).

The primary aim of the present study is to evaluate the highest concentrations of heavy metals (HMs) in Nile catfish (Clarias gariepinus, C. gariepinus) and water samples, as well as to investigate the efficiency of pomegranate peels (PPs) (supplemented either through water or diet) in enhancing fish immunity and counteracting the toxicity of high concentrations of HMs. Water and C. gariepinus samples were collected from two private fish farms in Al Sharkia Governorate. Mercury (Hg) showed the highest concentration (0.13 ppm). The adsorption capacity of PP was evaluated by testing different concentrations, 0.3, 0.6, 0.9, 1.2, and 1.5 g L-1, wherein 1.5 g L-1 revealed the highest Hg adsorption efficiency. The results indicated that Hg concentration was decreased with increased PP concentration until 72 h. In a trial that lasted for 60 days, 240 C. gariepinus (75.12 ± 3.12 g) were randomly divided into eight equal groups with three replicates per group. The first group (CT) served as the negative control (fish fed on a basal diet). The second group (PPW) was fed on a basal diet and supplemented with 0.3 g L-1 of PP via water. The third (PPD1) and fourth (PPD2) groups received basal diets enriched with 1 and 2 g PP powder/kg diet. respectively. The fifth group (Hg) served as the positive control that was fed on a basal diet and exposed to 0.13 ppm of Hg. The sixth (Hg + PPW), seventh (Hg + PPD1), and eighth (Hg + PPD2) groups were exposed to 0.13 ppm of Hg and received the same type of treatment as in second, third, and fourth groups. Hg exposure significantly elevated aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine levels, as well as oxidative stress biomarkers, including reduced glutathione (GSH) and malondialdehyde (MDA). Pomegranate supplementation through diet elevated the levels of red blood cells (RBCs), hemoglobin (Hb), packed cell volume (PCV), lysozyme, and anti-protease activity. Moreover, PP supplementation through water revealed minimum urea and creatinine levels, and the highest nitric oxide level. Moreover, Hg residue level in fish muscles noticeably decreased in the PP-treated groups. These results demonstrated the efficiency of PP supplementation (either through water or diet) in enhancing fish immunity and counteracting subchronic Hg toxicity.

Neurobehavioral and immune-toxic impairments induced by organic methyl mercury dietary exposure in Nile tilapia Oreochromis niloticus.

Although substantial knowledge of mercury toxicity in fish has been assembled; until now, studies investigating the toxic impacts in Nile tilapia (Oreochromis niloticus) following dietary exposure to organic methyl mercury (MeHg) are less prolific. Accordingly, the current study aimed to evaluate the impacts of MeHg on neurobehavioral and immune integrity in Nile tilapia after dietary exposure. Two hundred and twenty-five juvenile Nile tilapia (19.99 ± 0.33 g) were allocated into five groups in triplicates (15 fish/replicate). G1, G2, G3, G4, and G5. O. niloticus were fed corresponding basal diets containing 0, 0.5, 1, 1.5, and 2 mg/kg diet MeHg chloride (MeHgCl) daily for 30 days, zero value represented the control G1 group. The results showed that MeHg induced significant alterations in O. niloticus behavior, the swimming behavior was significantly decreased, while scratching, biting, and fin tugging behaviors were significantly augmented. Moreover; chasing, mouth pushing, and butting behaviors were significantly increased in all the exposed groups. MeHg significantly decreased brain acetylcholine esterase (AChE) and serum immunoglobulin M (IgM) levels in all the exposed groups. Meanwhile, serum levels of lysozyme (LYZ), nitric oxide (NO), superoxide dismutase (SOD) malondialdehyde (MDA), protein carbonyl (PCO), and 8 hydroxy 2 deoxyguanosine (8OH2dG) were significantly elevated in all the exposed groups except for serum reduced glutathione (GSH) content was significantly decreased implying oxidative stress (OS), lipid peroxidation (LPO), protein, DNA damage and impaired immune response of the exposed tilapia. MeHg significantly altered transcriptional expression of immune-related genes including (TNF-α, IL-1ß, and IL-8, and IL-10) in all the exposed groups. From the obtained outcomes, the present research is the premier to investigate that dietary MeHg exposure in O. niloticus significantly induced neurobehavioral and immune defense impairments in a dose-related manner. This study exhibits that dietary MeHg may pose a potential threat to the O. niloticus populations.

Replacement of dietary fish oil with plant oils improves the immunological responses and the antioxidant status in Oreochromis niloticus exposed to suboptimal temperature.

Here, we investigated the effects of total dietary fish oil (FO) substitution with plant oil (PO) on hematological indices, immune status, antioxidant activity, IL1ß and TNF-α gene expression, and hypoxia stress resistance in Oreochromis niloticus at suboptimal temperatures. Fish (n = 360) were randomly divided into 12 circular fiberglass tanks (500 L; 3 replicates for each dietary group, 30 fish/replicate, 90 fish/group). The control group was fed a basal diet with FO as the lipid source. The CO, SFO, and LSO groups were fed a basal diet with complete replacement of FO with corn, sunflower, and linseed oils, respectively. After 4 weeks, no effects on hematological indices were observed in fish fed the experimental diets. The LSO and CO groups showed a significant increase in γ globulin levels. The highest levels of non-specific immune parameters, antioxidant activity, and IL-1ß and TNF-α gene expressions were recorded in the LSO group. The LSO group also exhibited good resistance to hypoxia stress. Therefore, the total dietary substitution of FO with PO (especially LSO and CO) is recommended as a valuable strategy to ameliorate the immunosuppressive effects of suboptimal temperatures and enhance the resistance of O. niloticus to hypoxia stress.

Comparative study of three predominant gut Bacillus strains and a commercial B. amyloliquefaciens as probiotics on the performance of Clarias gariepinus.

The present study was conducted to evaluate the supplementation of three autochthonous Bacillus strains (B. subtilis, B. amyloliquefaciens and B. cereus) and a commercial B. amyloliquefaciensin doses of 1 × 1010 CFU/kg on the growth performance, hematology, antioxidant activities, digestive enzyme levels, immune status and disease resistance of Clarias gariepinus. A total of 300 fish (75.23 ±â€¯1.6 g) were randomly divided into 5 groups (each group was subdivided into 2 subgroups, 30 fish/each). The control group was fed basal diet (D0). Diets D1, D2, D3 and D4were supplemented with B. subtilis, B. amyloliquefaciens, B. cereus and a commercial B. amyloliquefaciens, respectively. During the course of the experiment, D3 showed the best body weight, weight gain, specific growth rate and food conversion ratio. The measured hemogram blood parameters had the highest significant increase in D3. WBCs and monocyte counts had no significant differences among the experimental groups. The serum antioxidant and digestive enzymes were the highest in D3 and were the lowest in D0. After 15 d, the non-specific immune parameters were markedly increased in fish fed probiotic-containing diet compared with the control. After 30 d, the highest significant immune parameters were observed in D3; D1 and D2 had no significant differences in serum lysozyme activity, nitric oxide and IgM compared with D0. Myostatin cDNA levels were adversely affected by probiotic supplements compare with the control. The PACAP expression showed the highest significant value in D3 followed by D1and D4then D2. The relative survival percentages of the Aeromonas sobria challenged C. gariepinus were the highest in D3, D2, D4 and then D1. Among the three isolated Bacillus species, dietary supplementation with the B. cereus had the highest performance in C. gariepinus compared with the commercial B. amyloliquefaciens and the control group.

Effect of dietary yeast nucleotide on antioxidant activity, non-specific immunity, intestinal cytokines, and disease resistance in Nile Tilapia.

The present study investigated the effects of dietary supplementation of yeast nucleotides on the hematology, antioxidant activity, non-specific immunity, expression of intestinal cytokines, and disease resistance in Nile Tilapia (Oreochromis niloticus). Fish weighing 42.90 ±â€¯0.14 g were randomly divided into four groups. Each group was set in triplicate (15 fish per replicate). Fish were fed on four dietary levels of yeast nucleotides (NTs) supplemented with the basal diet 0% (control), 0.05%, 0.15%, and 0.25% NTs. Significantly higher total serum protein, albumin, total serum globulin, total WBC counts, and lymphocyte and granulocyte contents were recorded in 0.25% NT group as compared to the control. The albumin/globulin ratio (A:G) showed a considerable decrease in the 0.25% NT group. The non-specific immune parameters; serum killing percentage, lysozyme activity, nitric oxide assay, IgM levels, and anti-protease activity, were significantly higher in the 0.25% NT group as compared to the control. Moreover, a 15-day feeding trial demonstrated improved results in terms of serum lysozyme activity, nitric oxide assay, IgM levels, and anti-protease activity than a 30-day feeding trial. A significant increase in the anti-oxidant status of O. niloticus was noticed, as reflected by increased superoxide dismutase and malondialdehyde activity in the serum of 0.25% NT group compared to the control, while glutathione peroxidase displayed a significant increase in all groups as compared to the control. The intestinal cytokines TGF-ß, IL-1ß, IL-10ß, and TNF-α mRNA levels showed a pattern of 0.25% NT > 0.15% NT > 0.05% NT > 0% NT, as relative to the control Ef-1α levels. The relative survival percentages of fish fed on yeast nucleotide-supplemented diets, as analyzed by exposure to Aeromonas sobria, were significantly better than the control group. In conclusion, dietary yeast nucleotide administration at 0.25% improved blood proteins, leukocytes, antioxidant activity, non-specific immunity, cytokine gene expression, and disease resistance of Nile Tilapia.

Influences of Chlorella vulgaris dietary supplementation on growth performance, hematology, immune response and disease resistance in Oreochromis niloticus exposed to sub-lethal concentrations of penoxsulam herbicide.

Little is known regarding the impact of penoxsulam, a fluorinated benzenesulfonamid rice herbicide, on Oreochromis niloticus (O. niloticus). Therefore, the current study was undertaken to highlight the effects of penoxsulam exposure on O. niloticus and to evaluate the advantages of Chlorella vulgaris (CV) dietary supplementation against the induced effects. The 96-h lethal concentration 50 (LC50) penoxsulam value for O. niloticus was estimated at 8.948 mg/L by probit analysis in a static bioassay experiment. Next, 360 healthy fish were randomly allocated into 6 treatment groups. The T1 group served as the negative control and was fed a basal diet. The T2 group served as the positive control and was fed a basal diet supplemented with 10% CV. The fish in the T3 and T4 groups were exposed to 1/10 the 96-h LC50 of penoxsulam (0.8948 mg/L) and were fed the basal diet alone or the basal diet supplemented with 10% CV, respectively. The fish in the T5 and T6 groups were exposed to 1/5 the 96-h LC50 of penoxsulam (1.7896 mg/L) and fed the basal diet alone or the basal diet supplemented with 10% CV, respectively. Sub-acute penoxsulam exposure significantly altered hematological indices, as well as compromised the fish's immune defense mechanisms, including the phagocytic percentage, phagocytic index, nitric oxide production, immunoglobulin M levels and lysozyme, anti-trypsin and bactericidal activities subsequently decreasing O. niloticus's resistance to the Aeromonus sobria challenge and increasing disease symptoms and the mortality rate. Furthermore, sub-chronic penoxsulam exposure markedly altered growth performance, oxidant/antioxidant status and liver status and down-regulated the expression of interleukin-1ß (IL-1ß) and tumor necrosis-α (TNF-α). Interestingly, incorporating 10% CV into the diet protects fish against sub-acute penoxsulam-induced immunotoxicity via improvement of immune responses that increases the resistance against bacterial infection. Further, it improved the growth performance, oxidant/antioxidant status, liver status and markedly up-regulated immune-related gene expression, IL-1ß and TNF-α, in the spleens of fish sub-chronically exposed to penoxsulam. These outcomes showed that dietary CV supplementation can protect the commercially valuable freshwater fish O. niloticus against penoxsulam toxicity and may be a potential feed supplement for Nile tilapia in aquaculture.

In Vitro Selection and Identification of Potential Probiotics Isolated from the Gastrointestinal Tract of Nile Tilapia, Oreochromis niloticus.

Fish gut bacteria can be used as probiotics for aquaculture. The aim of this study is to screen and identify beneficial probiotic bacteria from the gut of Nile tilapia, Oreochromis niloticus. Nine out of one hundred thirty-five isolates were non-pathogenic through intraperitoneal injection and had antibacterial activities with at least a strain from the five isolated fish pathogens, Aeromonas sobria, Aeromonas hydrophila, Pseudomonas aeruginosa, Pseudomonas putida, and Staphylococcus aureus. Further tests showed that such isolates can survive in the presence of high bile concentration (10%) and at different acidic pH values. A strains (14HT) was sensitive to all selected antibiotics, two strains were (9HT and 11HT) resistant to streptomycin and three strains (9HT, 11HT and 38HT) had resistance to two antibiotics. Four isolates (11HT, 33HT, 38HT and 41HT) had an amylase and a protease activities and one strain (47HT) showed only amylase activity. Based on 16S rRNA gene analysis, the isolated strains were identified as follows: Lactococcus lactis (8HT, 9HT, 11HT and 33HT); Enterococcus faecalis (14HT), Lysinibacillus sp. (38HT) and Citrobacter freundii (39HT, 41HT and 47HT).

Efficacy of Spirulina platensis diet supplements on disease resistance and immune-related gene expression in Cyprinus carpio L. exposed to herbicide atrazine.

The present study evaluated the immunotoxicological effects of the herbicide atrazine (ATZ) at sub-lethal concentrations and the potential ameliorative influence of Spirulina platensis (SP) over a sub-chronic exposure period on Cyprinus carpio L., also known as common carp. Common carp was sampled after a 40-days exposure to ATZ (428 µg/L) and SP (1%), individually or in combination to assess the non-specific immune response, changes in mRNA expression of immune-related genes [lysozyme (LYZ), immunoglobulin M (IgM), and complement component 3 (C3)] in the spleen, and inflammatory cytokines (interleukins IL-1ß and IL-10) in the head kidney using real-time PCR. Additionally, disease resistance to Aeromonas sobria was evaluated. The results revealed that ATZ exposure caused a significant decline in most of the hematological variables, lymphocyte viability, and lysozyme and bactericidal activity. Moreover, ATZ increased the susceptibility to disease, reflected by a significantly lower post-challenge survival rate of the carp. ATZ may induce dysregulated expression of immune-related genes leading to downregulation of mRNA levels of IgM and LYZ in the spleen. However, expression of C3 remained unaffected. Of the cytokine-related genes examined, IL-1B was up-regulated in the head kidney. In contrast, the expression of IL-10 gene was down-regulated in the ATZ-exposed group. The SP supplementation resulted in a significant improvement in most indices; however, these values did not match with that of the controls. These results may conclude that ATZ affects both innate and adaptive immune responses through the negative transcriptional effect on genes involved in immunity and also due to the inflammation of the immune organs. In addition, dietary supplements with SP could be useful for modulation of the immunity in response to ATZ exposure, thereby presenting a promising feed additive for carps in aquaculture.

Effects of dietary acidifiers on growth, hematology, immune response and disease resistance of Nile tilapia, Oreochromis niloticus.

Organic acids or their salts can be used as feed additives in aquaculture. This study was conducted to evaluate the use of a mixture of formic acid, propionic acid and calcium propionate compared with oxytetracycline (OTC). A total of 720 apparently healthy Oreochromis niloticus fingerlings with an average body weight of 28.8 ± 0.14 g (mean ± SE) were randomly divided into four equal groups (G1, G2, G3and G4). G1 was fed a basal diet with no additive as the control group, while G2 and G3 were fed a formic and propionic acid/salt mixture in 1 and 2 g/kg, respectively. G4 was fed OTC (0.5 g/kg). Each group was subdivided into tow subgroups A and B (30 fish/subgroup) in triplicate. The first subgroup was used to evaluate growth performance, hematology and body composition for 60 d. The second subgroup was used to examine immunity, gut microbiota and resistance to infection for 30 d. At the end of the feeding period (60 d), G3 had significant improvements in final body weight (FBW), weight gain (WG), specific growth rate (SGR) and food conversion ratio (FCR) compared with other groups. The total erythrocyte count, hemoglobin content, platelet count, hematocrit, mean corpuscular hemoglobin and total leukocyte count were significantly increased in G3 and G2 compared with G1 and G4. Mean corpuscular volum, lymphocyte and neutrophil percentages had the highest significant improvement in G3. There were no significant differences among the groups in mean corpuscular hemoglobin concentration and monocyte percentage. The protein and fat contents of the whole body were the highest in G3. The widest inhibition zones against Aeromonas sobria were at the 30, 40 and 50% concentrations of acidifiers, which were equivalent to OTC (30 µg). G3 showed the lowest total gastrointestinal bacterial counts, followed by G2. After 15 and 30 d, G3 had the highest serum killing, lysozyme and nitric oxide activities. Serum lysozyme activity and nitric oxide assay had no significant difference between G1 and G2 after 30 d. The lowest immune parameters were recorded in G4. After 30 d, the highest expression of interleukin-1ß and tumor necrosis factor-alpha in the liver and kidney were found in G3. The best protection against challenged Aeromonas sobria was in G3, followed by G2 and G4. Dietary supplementation with a combination of formic acid, propionic acid and calcium propionate improves the performance of Nile tilapia.