Nelumbo nucifera synthesized selenium nanoparticles modulate the immune-antioxidants, biochemical indices, and pro/anti-inflammatory cytokines pathways in Oreochromis niloticus infected with Aeromonas veronii.

Bacterial infection is considered one of the major issues in fish culturing that results in economic losses. Metal nanoparticles are a cutting-edge and effective disease management and preventive strategy because of their antibacterial ability. In this investigation, the selenium nanoparticles were prepared by a biological method using Nelumbo nucifera leaves extract. The in-vitro antibacterial activity of N. nucifera synthesized selenium nanoparticles (NN-SeNPs) was tested against Aeromonas veronii. A treatment assay was conducted on 210 Oreochromis niloticus (average body weight: 27 ± 2.00 g). A preliminary approach was conducted on 90 fish for determination of the therapeutic concentration of NN-SeNPs which was found to be 4 mg/L. Fish (n = 120) were categorized into four groups for 10 days; G1 (control) and G2 (NN-SeNPs) were non-challenged and treated with 0 and 4 mg/L NN-SeNPs, respectively. While, G3 and G4 were infected with 2 × 106 CFU/mL of A. veronii and treated with 0 and 4 mg/L NN-SeNPs, respectively. NN-SeNPs exhibited an inhibition zone against A. veronii with a diameter of 16 ± 1.25 mm. The A. veronii infection increased the hepato-renal biomarkers (alanine and aspartate aminotransferases and creatinine) than the control group. An oxidative stress was the consequence of A. veronii infection (higher malondialdehyde and hydrogen peroxide levels with lower glutathione peroxidase superoxide, dismutase, and catalase activity). A. veronii infection resulted in lower immunological biomarker values (immunoglobulin M, lysozyme, and complement 3) with higher expression of the inflammatory cytokines (interleukin-1ß and tumor necrosis factor-ɑ) as well as lower expression of the anti-inflammatory cytokines (interleukin-10 and transforming growth factor-ß). Therapeutic application with 4 mg/L NN-SeNPs prevented the disease progression; and modulated the hepato-renal function disruptions, oxidant-immune dysfunction, as well as the pro/anti-inflammatory cytokines pathway in the A. veronii-infected fish. These findings suggest that NN-SeNPs, employed as a water therapy, can safeguard fish from the harmful effects of A. veronii and serve as a promising antibacterial agent for sustainable aquaculture.

Effect of dietary intervention with Capsicum annuum extract on growth performance, physiological status, innate immune response, and related gene expression in Nile tilapia.

The red pepper (Capsicum annuum) has gained great attention recently because of its biological and pharmacological characteristics. The present approach aimed to evaluate the effects of C. annuum alcoholic extract (CAE) supplementation on Nile tilapia (Oreochromis niloticus) growth performance, physiological status, some metabolic, immune, and regulatory genes expression, and resistance against Streptococcus agalactiae infection. Fish (22.26 ± 0.19 g) were assigned to four treatments (five replicates, each with 10 fish replicate-1) and fed tested diets for 60 days. The experimental diets were supplemented with CAE at 0, 0.4, 0.8, and 1.6 g kg-1, expressed as CAE0, CAE0.4, CAE0.8, and CAE1.6, respectively. The findings exhibited that CAE dietary supplementation improved growth performance, feed utilization, elevated growth hormone level, and digestive enzyme activities (amylase and protease), and lowered leptin hormone in a level-dependent manner. Boosting the mRNA expression of the transporter proteins (solute carrier family 15 member 2 and solute carrier family 26 member 6) and insulin-like growth factor-1 genes with a decrease in the myostatin gene expression was noticed in the CAE-fed groups. The innate immune (serum bactericidal activity %, complement 3, and phagocytic activity %) and antioxidant (glutathione peroxidase and total antioxidant capacity) parameters were significantly (p < 0.05) improved, and the serum malondialdehyde level was significantly decreased by CAE dietary inclusion. A marked upregulation in the mRNA expression of interleukins (il-1ß, il-6, il-8, and il-10), transforming growth factor-ß, glutathione peroxidase, and glutathione synthetase genes were observed in CAE-fed groups. Dietary CAE decreased the cumulative mortalities after the challenge with S. agalactiae by 20, 13.33, and 10% in CAE0.4, CAE0.8, and CAE1.6, respectively, compared to the control (40%). Overall, dietary supplementation with CAE could improve growth performance and physiological status, and modulate the expression of several regulatory genes in Nile tilapia. The recommended level of CAE is 1.6 g kg-1 to augment growth and health status.

The Antioxidant Role of a Taurine-Enriched Diet in Combating the Immunotoxic and Inflammatory Effects of Pyrethroids and/or Carbamates in Oreochromis niloticus.

Indiscriminate use of insecticides is a major concern due to its ubiquitous occurrence and potential toxicity to aquatic animals. This study investigated the adverse effects of lambda-cyhalothrin (LCT; C23H19ClF3NO3) and methomyl (MTM; C5H10N2O2S) on immune system modulations and growth performance of juvenile fishes. The supportive role of a taurine (TUR; C2H7NO3S)-supplemented diet was also evaluated. Juvenile O. niloticus fishes were exposed to LCT (0.079 µg/L), MTM (20.39 µg/L), or both in water and were fed on a basal diet only or taurine-supplemented basal diet. Exposure to LCT and MTM retarded growth and increased mortality rate. LCT and MTM reduced antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) and innate and humoral immunity but upregulated interleukin and chemokine expressions. Moreover, exposure to LCT and MTM elevated 8-OHdG levels and increased the mortality of Oreochromis niloticus after the experimental bacterial challenge. The TUR-enriched diet enhanced antioxidant enzymes and acted as a growth promoter and anti-inflammatory agent. TUR can modify innate and adaptive immune responses. Furthermore, TUR supplementation is a beneficial additive candidate for mitigating LCT and MTM toxicities mixed with O. niloticus aquafeed.