A blend of chitosan-vitamin C and vitamin E nanoparticles robust the immunosuppressed- status in Nile tilapia treated with salt

In aquaculture, fish are exposed to many stressors, such as climate changes and infectious diseases that affect their performance, immunity, and welfare. Freshwater fish subjected to salt bath become exhausted and stressed. In this experiment, Nile tilapia were exposed to a salt bath at a dose of 30 ppt for 30 min a day. Vitamin C and vitamin E are well-known antioxidants that are used in aquaculture. Fish received dietary nanoparticles of chitosan-vitamin C and chitosan-vitamin E (CCE-NPs) for different periods (7 and 14 days) pre- (G2) and post-salt treatment (G3). In the control fish (G1), cortisol 5.44 µg/dL and glucose 91.67 mg/dL were significantly up-regulated post-salt treatment by 1 h and 24 h, respectively, whereas those (G2) fed CCE-NPs diet had significantly lower values of 4.72 and 3.25 µg/dL; 86.3 and 84.3 mg/dL, respectively. A rapid decrease of glucose 68.3 and 66.3 mg/dL was noticed in those (G2) fed CCE-NPs diet compared to the control 84.67 mg/dL at 48 h post-stress. Regardless of the supplementation period, fish (G2) could partially restore normal food reflex at 48 h (post-salt bath) and fully restored at 72 h compared to 7 days in the control (G1). After 48 h, fish that received dietary CCE-NPs (G2 and G3) restored normal mucus lysozyme levels, whereas the control did not restore pre-treatment values till the seventh day. Mucus antibacterial activity, fish received rapid dietary CCE-NPs (G2) and partially restored average values (pre-salt bath) at 96 h. The salt treatment could provoke gene expression of pro-inflammatory cytokines interleukin (IL-1β) and tumor necrosis (TNF)-α in the head kidney of fish at 24 h post-salt bath to 5.9-8.35 fold-change, respectively, with a rapid decline in fish (G2) the gene expression. Post-salt bath (24 h), the gene expression of glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) was higher in fish (G2) than in the control group (G1) regardless of the supplementation period (7 and 14 days). Bacterial infection S. agalactiae (OL471408), a significantly lower MR was recorded in G2 at 40% and 33.3% compared to the control G1 MR (53.3%), with an RPL of 24.95% and 37.5%. In conclusion, Nile tilapia treated with a 30 ppt salt became more vulnerable to S. agalactiae. Adding CCE-NPs to the Nile tilapia diet for 7- and 14-day pre-salt bath could increase immune and antioxidant-related gene expression to counteract S. agalactiae infection.

Dietary nanocomposite of vitamin C and vitamin E enhanced the performance of Nile tilapia

Nowadays, nanomaterials enter high numbers of daily used products and drug manufacture. A nanocomposite of vitamins C (VC) and vitamin E (VE) with chitosan as a vehicle and protector was used in a comparative eight-week feeding study, Nile tilapia weighing 31.2 ± 0.36 g distributed in seven groups and fed (G1) basal diet, (G2) bulk VC, (G3) VC- nanoparticles (NPs), (G4) bulk VE, (G5) VE-NPs, bulk VCE (G6), and (G7) VC plus VE (VCE)-NPs, respectively. The Nile tilapia-fed nanocomposite vitamins had significantly higher growth performance compared to the control; VCE-NPs had the superiority among tested supplementations where total weight gain (63.6 g), daily weight gain (1.13 g), relative growth rate (206.1%) with lower feed conversion rate (1.6) and insignificant feed intake (101.5 g). Overall, the level of liver enzymes was significantly decreased in fish serum after eight-week nanocomposite supplementation, and dietary VCE-NPs caused a significant reduction of serum AST (18.45 IU/L) and ALT (14.77 IU/L) compared to the control 25.5 IU/L and 17.6 IU/L, respectively. Fish fed dietary VCE-NPs, VC-NPs, and VE-NPs had significant enhancement of RBCs 4.2 × 106/μL, 3.8 × 106/μL, and 3.55 × 106/μL; WBCs 46.15 × 103, 42.9 × 103, and 44 × 103/μL, respectively, Also TP was significantly higher 6.38 g/dL in VCE-NPs group compared to the control and the other treatments. Over all, the dietary nanocomposite vitamins boost the innate immunity of the experimental Nile tilapia, the oxidative burst activity (OBA), phagocytic activity (PA), phagocytic index (PI), and serum antibacterial (SAA) were significantly increased compared to those received bulk vitamins and the control. The activity of antioxidant biomarkers in fish serum including glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (TAC), glutathione reductase (GR), and myeloperoxidase (MPO) showed a rise in the serum of Nile tilapia received nano- and bulk-form of VC and VCE compared to the control and both forms of VE. Furthermore, the level of malondialdehyde (MDA), reduced glutathione (GSH), and oxidized glutathione (GSSG) were significantly increased in the fish serum following the trend of antioxidants enzymes. In conclusion, a dietary nanocomposite of vitamin C and vitamin E enhanced Nile tilapia's growth performance and feed utilization. It could also improve health status and immune response. The values of antioxidant biomarkers indicated that the nanocomposite could help the fish body scavenge the generated reactive oxidative species (ROS).

Dietary Chitosan Attenuates High-Fat Diet-Induced Oxidative Stress, Apoptosis, and Inflammation in Nile Tilapia (Oreochromis niloticus) through Regulation of Nrf2/Kaep1 and Bcl-2/Bax Pathways

Fatty liver injury is a prevalent condition in most farmed fish, yet the molecular mechanisms underpinning this pathology remain largely elusive. A comprehensive feeding trial spanning eight weeks was conducted to discern the potential of dietary chitosan in mitigating the deleterious effects of a high-fat diet (HFD) while concurrently exploring the underlying mechanism. Growth performance, haemato-biochemical capacity, antioxidant capacity, apoptotic/anti-apoptotic gene expression, inflammatory gene expression, and histopathological changes in the liver, kidney, and intestine were meticulously assessed in Nile tilapia. Six experimental diets were formulated with varying concentrations of chitosan. The first three groups were administered a diet comprising 6% fat with chitosan concentrations of 0%, 5%, and 10% and were designated as F6Ch0, F6Ch5, and F6Ch10, respectively. Conversely, the fourth, fifth, and sixth groups were fed a diet containing 12% fat with chitosan concentrations of 0%, 5%, and 10%, respectively, for 60 days and were termed F12Ch0, F12Ch5, and F12Ch10. The results showed that fish fed an HFD demonstrated enhanced growth rates and a significant accumulation of fat in the perivisceral tissue, accompanied by markedly elevated serum hepatic injury biomarkers and serum lipid levels, along with upregulation of pro-apoptotic and inflammatory markers. In stark contrast, the expression levels of nrf2, sod, gpx, and bcl-2 were notably decreased when compared with the control normal fat group. These observations were accompanied by marked diffuse hepatic steatosis, diffuse tubular damage, and shortened intestinal villi. Intriguingly, chitosan supplementation effectively mitigated the aforementioned findings and alleviated intestinal injury by upregulating the expression of tight junction-related genes. It could be concluded that dietary chitosan alleviates the adverse impacts of an HFD on the liver, kidney, and intestine by modulating the impaired antioxidant defense system, inflammation, and apoptosis through the variation in nrf2 and cox2 signaling pathways.

Prophylactic and Therapeutic Efficacy of Ultrasonicated Rosmarinus officinalis Ethanolic Extract and its Chitosan-Loaded Nanoparticles Against Eimeria tenella Infected Broiler Chickens

PURPOSE

The in vivo efficacy of ultrasonicated Rosmarinus officinalis ethanolic extract (UROEE) and its chitosan-loaded nanoparticles (UROEE-CsNPs) was investigated as a dietary prophylactic agent and as a therapeutic treatment against Eimeria tenella infected broiler chickens.

METHODS

Chickens were infected with 4 × 104 E. tenella oocysts at 21 days old for primary infection and with 8 × 104 oocysts at 35 days old for secondary infection. Eleven experimental groups were conducted. Dietary addition of 100 mg/kg UROEE and 20 mg/kg for CsNPs as well as UROEE-CsNPs were included for prophylactic groups from day 1 to 42. The same doses were used for therapeutic treatment groups for 5 constitutive days. Oocyst output in feces was counted. Histopathological and immunohistochemical studies were conducted. Gene expression of pro-inflammatory cytokines as IFN-γ, IL-1β and IL-6 as well as anti-inflammatory cytokines as IL-10 and TGF-β4 was analyzed using semi-quantitative reverse transcriptase-PCR.

RESULTS

The results showed an efficacy of UROEE, CsNPs and UROEE-CsNPs in reduction of oocyst excretion and improving the cecal tissue architecture. CD4+ and CD8+ T lymphocytes protein expression were reduced. E. tenella infection lead to upregulation of pro-inflammatory cytokines as IFN-γ, IL-1β, IL-6 and anti-inflammatory cytokines as TGF-β4 following primary infection, while their expression was downregulated following secondary infection.

CONCLUSION

The dietary prophylactic additives and therapeutic treatments with UROEE, CsNPs and UROEE-CsNPs could decrease the inflammatory response to E. tenella as indicated by oocyst output reduction, histopathological improvements, CD4+ and CD8+ T cells protein expression reduction as well as reducing mRNA expression levels of the tested cytokines following primary and secondary infections. Consequently, these results will help to develop better-combating strategies for the control and prevention of coccidiosis on poultry farms as a dietary prophylactic agent or as a therapeutic treatment.

Chitin, chitosan and chitooligosaccharides as potential growth promoters and immunostimulants in aquaculture: A comprehensive review

There is a stable growth in aquaculture production to avoid seafood scarcity. The usage of eco-friendly feed additives is not only associated with aquatic animal health but also reduces the risk of deleterious effects to the environment and consumers. Aquaculture researchers are seeking dietary solutions to improve the growth performance and yield of target organisms. A wide range of naturally derived compounds such as probiotics, prebiotics, synbiotics, complex carbohydrates, nutritional factors, herbs, hormones, vitamins, and cytokines was utilized as immunostimulants in aquaculture. The use of polysaccharides derived from natural resources, such as alginate, agar, laminarin, carrageenan, fucoidan, chitin, and chitosan, as supplementary feed in aquaculture species has been reported. Polysaccharides are prebiotic substances which are enhancing the immunity, disease resistance and growth of aquatic animals. Further, chitin (CT), chitosan (CTS) and chitooligosaccharides (COS) were recognized for their biodegradable properties and unique biological functions. The dietary effects of CT, CTS and COS at different inclusion levels on growth performance, immune response and gut microbiota in aquaculture species has been reviewed. The safety regulations, challenges and future outlooks of CT, CTS and COS in aquatic animals have been discussed in this review.

Long-Term Application of a Synbiotic Chitosan and Acinetobacter KU011TH Mixture on the Growth Performance, Health Status, and Disease Resistance of Hybrid Catfish (Clarias gariepinus × C. macrocephalus) during Winter

The effects of potential synbiotic chitosan and Acinetobacter KU011TH mixture on growth performance, immune response, and A. hydrophila resistance were investigated for the first time. The control group was fed a basal diet (A), and group B was given the formula B diet that was supplemented with chitosan at 20 mL/kg diet via top dressing. The other synbiotic groups, C, D, and E, were top-dressed with the target probiotics at 1 × 10⁸, 1 × 10⁹, and 1 × 10¹⁰ CFU/kg diet, respectively, and coated with the same concentration of chitosan. Fish were continuously fed the five different feeds for 16 weeks during winter. At the end of the trial, the growth parameters of the test groups did not significantly differ from those of the control (p > 0.05). All the symbiotic-chitosan treatments significantly increased various hematological and serum immune parameters. Moreover, the expression levels of immune-related genes were strongly elevated in the head kidney and spleen, whereas upregulated expression was observed in the liver and whole blood (p < 0.05). Survival analysis indicated that fish in groups B and C showed significantly higher survival (84.33 ± 2.21 and 79.50 ± 6.34%) than those in groups A, D and E (55.33 ± 8.82%-74.00 ± 6.50) (p < 0.05) after injection with A. hydrophila for 14 days.

The antibacterial activity and immunomodulatory effect of naturally synthesized chitosan and silver nanoparticles against Pseudomonas fluorescence infection in Nile tilapia (Oreochromis niloticus): An in vivo study

A sixty-day feeding trial was conducted to assess the effects of silver nanoparticles (AgNPs) and chitosan nanoparticles (CNPs) on the growth and immunity of Nile tilapia (Oreochromis niloticus), compared with the control group. CNPs and AgNPs were green synthesized and added to a control diet (30% crude protein) at levels of 2.0 g CNPs/kg diet and 1.0 mg AgNPs/kg diet. One hundred and eighty fish (101 ± 3.98 g) were randomly distributed into nine fiberglass tanks (200 cm × 200 cm x 100 cm, twenty fish each) to represent three equal groups (60 fish per group). After one and two months of the feeding trial, parameters of water quality, growth indices, hematology, and liver and kidney biomarkers were evaluated. At the end of the experiment, 10 fish from each group were challenged experimentally via the intraperitoneal injection with Pseudomonas fluorescence and fish mortality was observed for further ten days. Then, specimens from the liver, kidney, spleen, and anterior intestine were examined to assess the histopathological alterations. Incorporating a 2.0 g CNPs/kg diet was a promising growth enhancer; however, a 1.0 mg AgNPs/kg diet had no effects on tilapia performance. Furthermore, AgNPs appeared to reduce water pollution, leading to water filtration via decreasing both total dissolved solids (TDS) and electrical conductivity (EC). A significant role of AgNPs in improving tilapia^'s erythrogram (RBCs number and Hb concentration) was evident. Compared with the control group, both groups of CNPs and AgNPs improved non-specific immune parameters and showed defense effects against P. fluorescence. The fish mortality after P. fluorescence infection in CNPs and AgNPs-fed fish groups revealed significant decreases (P < 0.05) of 10% and 25%; respectively, while the control group exhibited a mortality rate of 40%. The current investigation evoked that using dietary CNPs (2.0 g/kg feed) as an antibacterial agent against P. fluorescence infection in Nile tilapia culture was better than dietary AgNPs (1.0 mg/kg diet) which, induced cells inflammation causing tissues necrosis.

The optimized inclusion level of Bacillus subtilis fermented Azolla pinnata in Nile tilapia (Oreochromis niloticus) diets: immunity, antioxidative status, intestinal digestive enzymes and histomorphometry, and disease resistance

A 95-day feeding trial was conducted to evaluate the outcomes of feeding Bacillus subtilis fermented Azolla (BSFA) on nonspecific immunity, antioxidative status, intestinal digestive enzymes and histomorphometry, and disease resistance in the Nile tilapia. We formulated five isonitrogenous and isocaloric experimental diets to incorporate BSFA at level of (0%, 15%, 30%, 45%, 60%). The growth performance parameters (FBW, BWG, SGR, PER, and FCR) revealed a significant increase in the BSFA30 tilapia group compared to the control group followed by BSFA45 (P < 0.05). The BSFA30 group exhibited the highest nonspecific immunity parameters including (lysozyme activity, phagocytic index, and phagocytic activity) compared to other groups (P < 0.05). SOD and GPx reported the highest values in the BSFA60 group. Nile tilapia carcass composition was not influenced by BSFA inclusion level (P > 0.05). Interestingly, Nile tilapia fed with BSFA15 diet exhibited the highest protease activity level (P < 0.05), while those fed on BSFA30 documented the highest amylase activity. Intestinal histomorphology was significantly enhanced with the gradual increase of administrated BSFA. Regarding the tilapia disease resistance against Aeromonas septicemia, BSFA significantly diminished the cumulative mortality compared to the control group. To sum up, BSFA was more effective in improving the growth performance and immunity of Nile tilapia.

Effects of Formulation on the Palatability and Efficacy of In-Feed Praziquantel Medications for Marine Finfish Aquaculture

Praziquantel (PZQ) provides an effective treatment against monogenean parasitic infestations in finfish. However, its use as an in-feed treatment is challenging due to palatability issues. In this study, five formulations of PZQ beads (1−4 mm) were developed using marine-based polymers, with allicin added as a flavouring agent. All formulations attained PZQ loading rates ≥74% w/w, and the beads were successfully incorporated into fish feed pellets at an active dietary inclusion level of 10 g/kg. When tested for palatability and digestibility in small yellowtail kingfish, the PZQ-loaded beads produced with alginate-chitosan, alginate-Cremophor® RH40, and agar as carriers resulted in high consumption rates of 99−100% with no digesta or evidence of beads in the gastrointestinal tract (GIT) of fish fed with diets containing either formulation. Two formulations produced using chitosan-based carriers resulted in lower consumption rates of 68−75%, with undigested and partly digested beads found in the fish GIT 3 h post feeding. The PZQ-loaded alginate-chitosan and agar beads also showed good palatability in large (≥2 kg) yellowtail kingfish infected with gill parasites and were efficacious in removing the parasites from the fish, achieving >90% reduction in mean abundance relative to control fish (p < 0.001). The two effective formulations were stable upon storage at ambient temperature for up to 18 months, showing residual drug content >90% compared with baseline levels. Overall, the palatability, efficacy and stability data collected from this study suggest that these two PZQ particulate formulations have potential applications as in-feed anti-parasitic medications for the yellowtail kingfish farming industry.

Dietary chitosan promotes the growth, biochemical composition, gut microbiota, hematological parameters and internal organ morphology of juvenile Barbonymus gonionotus

In this study, we determined the effects of dietary chitosan on the growth, biochemical composition, gut microbiota, and hematological and histological parameters of juvenile Barbonymus gonionotus. Three test diets containing three different concentrations (1, 2, and 3 g kg-1 feed) of dietary chitosan were formulated. A basal diet without dietary chitosan was considered a control, and the fish were reared for 60 days. Comparing the effects of the dietary chitosan-containing diets with those of the control diet, we found that dietary chitosan significantly improved the muscle growth, nutrient and mineral contents, hematological parameters, lactic acid bacterium abundance, and digestive enzyme activities of B. gonionotus. Moreover, dietary chitosan significantly inhibited the growth of pathogenic bacteria in fish. Interestingly, an increase in the dietary chitosan level significantly enhanced the protein contents of the muscles and inversely significantly decreased the lipid contents compared to those with the basal diet. Quantitative study revealed that dietary chitosan significantly enhanced the length of intestinal villi, and qualitative study showed that dietary chitosan considerably reduced the fat content in the liver and improved the morphology of the kidney compared to those with the basal diet. Taken together, our results suggest that the application of dietary chitosan at a dose of 1 g kg-1 feed produced the highest benefit to treated B. gonionotus, indicating its potential for safe use in aquaculture.

Gut immune-related gene expression, histomorphometry and hematoimmunological assays in Nile tilapia (Oreochromis niloticus) fed Aspergillus oryzae fermented olive cake

Fermentation strategy is well documented to improve the nutritional value of agricultural waste by-products such olive cake (OC), which, in turn, provides healthy, safe, and affordable feedstuff. This study assessed the combined impact of Aspergillus oryzae-fermented OC (AFOC) on the growth performance, intestinal morphometry, blood biochemistry, lysozyme activity, gut immune-related genes, and flesh quality of Nile tilapia. We divided 225 fish into five groups and further subdivided into three replicates (n = 15 each) and fed them five diets (Control, AFOC5, AFOC10, AFOC15, AFOC20) to determine AFOC nutritional value and its optimized incorporation level in the diet. The trial continued for 3 months. The crude protein content of OC improved by 7.77% after A. oryzae fermentation, while lipid content decreased by 14.19%. In addition, growth and feed utilization significantly improved at (10.8-11.2) % AFOC dietary level. High-density lipoprotein (HDL) significantly improved, and the serum lysozyme level was significantly higher in the AFOC10 group compared to other groups. Interestingly, gut-related inflammatory cytokines tumor necrosis factor alpha (TNF- α) and interleukin 1 beta (IL-1β) revealed higher relative mRNA expression in the AFOC10 group compared to other groups. The histomorphometric parameters was greatly influenced by the AFOC incorporation level (10%-20%). These findings suggested that A. orzae fermentation modifies the nutritional quality of OC, as seen through its positive impact on the growth performance, local and systemic immunity, and intestinal absorptive capacity of Nile tilapia. The recommended dose for dietary AFOC was around 11.

Chitin derivatives of NAG and chitosan nanoparticles from marine disposal yards and their use for economically feasible fish feed development

Globally, the disposal of shellfishery waste is a major challenge and causes a risk to the coastal region. For potential development in aquaculture, the use of safe supplements to improve fish production and health is important. Chitosan (CS) used as feed additives for several fish species that enhanced production and immunity. The present study was intended to assess the effect of feed additives N-acetyl-d-glucosamine (NAG) loaded chitosan nanoparticles (CSNPs) on productivity, survival rate, and protein conversion efficiency of Oreochromis niloticus (L.). This is the first report on the effect of CSNPs and NAG loaded CSNPs as feed additives enhanced growth performance and non-specific immunity of O. niloticus. CSNPs and NAG loaded CSNPs were synthesized and characterized by scanning and transmission electron microscope, FT-IR, X-ray diffraction, particle size distribution, and zeta sizer. Fish (15.30 ± 0.23 g) administered diets fortified with 0.0, 0.25, 0.5, 1.0, and 2.0 g CSNPs/kg feed loaded with NAG for 45 d. The diets containing 1.0 g/kg NAG loaded CSNPs enhanced specific growth rate, weight gain, survival rate, respiratory burst, and lysozyme activities of tilapia compared control group. The data shows biologically active CSNPs and NAG loaded CSNPs are potent antimicrobial agents against selected bacterial pathogens. In conclusion, the findings suggested that the dietary supplement containing NAG loaded CSNPs significantly increased immune-modulatory properties, growth performance, and enhanced their disease resistance of Nile tilapia.

Chitosan and chitooligosaccharides attenuate soyabean meal-induced intestinal inflammation of turbot (Scophthalmus maximus): possible involvement of NF-кB, activator protein-1 and mitogen-activated protein kinases pathways

An 8-week feeding experiment was conducted to investigate and confront the putative functions of chitosan (CTS) and chitooligosaccharide (COS) in the growth and homoeostasis of distal intestine in juvenile turbots fed diets containing soyabean meal (SBM). Three isolipidic and isonitrogenous diets were formulated by supplemented basal diet (based on a 400 g/kg SBM) with 7·5 g/kg CTS or with 2·0 g/kg COS. Our results indicated that both CTS and COS supplementation could significantly improve (i) the growth performance and feed efficiency ratio; (ii) antioxidant activity driven by metabolic enzymes (i.e. catalase, glutathione reductase, glutathione peroxidase and superoxide dismutase); (iii) glutathione levels; (iv) acid phosphatase and lysozyme activity and (v) IgM content. As a result, these two particular prebiotics were able to significantly attenuate the histological alterations due to local inflammation as well as to decrease the transcriptional levels of proinflammatory cytokines (i.e. IL-1β, IL-8 and TNF-α) and major pathway effectors (i.e. activator protein-1 (AP-1), NF-кB, p38 mitogen-activated protein kinase, c-Jun N-terminal kinase and extracellular regulated kinase). High-throughput sequencing data indicated that dietary CTS and COS could significantly decrease the diversity of intestinal bacteria but elevate the relative abundances of Bacillus, Lactobacillus and Pseudomonas genera. Altogether, these findings suggest that CTS and COS can improve growth of turbot, enhance intestinal immune and anti-oxidant systems and promote the balance of intestinal microbiota. The protective effects, elicited by these two prebiotics, against SBM-induced inflammation could be attributed to their roles in alleviating the overexpression of inflammatory cytokines by possibly down-regulating NF-кB, AP-1 and/or mitogen-activated protein kinases pathways.

Marine-Derived Chitosan Nanoparticles Improved the Intestinal Histo-Morphometrical Features in Association with the Health and Immune Response of Grey Mullet (Liza ramada)

Marine-derived substances are known for their beneficial influences on aquatic animals’ performances and are recommended to improve intestinal health, immunity, and anti-oxidative status. The present study investigates the role of chitosan nanoparticles on the intestinal histo-morphometrical features in association with the health and immune response of Grey Mullet (Liza ramada). Chitosan nanoparticles are included in the diets at 0, 0.5, 1, and 2 g/kg and introduced to fish in a successive feeding trial for eight weeks. The final body weight (FBW), weight gain (WG), and specific growth rate (SGR) parameters are significantly increased while feed conversion ratio (FCR) decreases by chitosan nanoparticles compared to the control (p < 0.05). The morphometric analysis of the intestines reveals a significant improvement in villus height, villus width, and the number of goblet cells in chitosan-treated groups in a dose-dependent manner. Additionally, there is a positive correlation between the thickness of the enterocyte brush border and the chitosan dose, referring to an increasing absorptive activity. Histologically, the intestinal wall of Grey Mullet consists of four layers; mucosa, sub-mucosa, tunica muscularis (muscular layers), and serosa. The histological examination of the L. ramada intestine shows a normal histo-morphology. The epithelial layer of intestinal mucosa is thrown into elongated finger-like projections, the intestinal villi. The values of hemoglobin, hematocrit, red blood cells (RBCs), total protein (TP), albumin, and globulin are significantly increased in fish fed 1, and 2 g/kg of chitosan nanoparticles compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest levels of TP and albumin are observed in fish fed 1 g/kg diet (p < 0.05). The lysozyme activity and phagocytic index are significantly enhanced by feeding chitosan nanoparticles at 0.5, 1, and 2 g/kg, whereas the phagocytic activity is improved in fish fed 1 and 2 g/kg (p < 0.05). The highest lysozyme activity and phagocytic index are observed in fish fed 1 g/kg. SOD is significantly activated by feeding chitosan nanoparticles at 1 g/kg. Simultaneously, glutathione peroxidase (GPx) and catalase (CAT) activities also are enhanced by feeding chitosan at 1 and 2 g/kg, compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest GPx and CAT activities are observed in fish fed 1 g/kg (p < 0.05). Conversely, the malondialdehyde (MDA) levels are decreased by feeding chitosan at 1 and 2 g/kg, with the lowest being in fish fed 1 g/kg (p < 0.05). To summarize, the results elucidate that L. ramada fed dietary chitosan nanoparticles have a marked growth rate, immune response, and anti-oxidative response. These improvements are attributed to the potential role of chitosan nanoparticles in enhancing intestinal histo-morphometry and intestinal health. These results soundly support the possibility of using chitosan nanoparticles at 1–2 g/kg as a feasible functional supplement for aquatic animals.

Effects of oligochitosan on the growth, immune responses and gut microbes of tilapia (Oreochromis niloticus)

The immunomodulatory effects of oligochitosan have been demonstrated in several fish. However, the underlying mechanisms are not well characterized. The profound interplay between gut microbes and aquaculture has received much scientific attention but understanding the alternations of microbes populating in gut of tilapia (Oreochromis niloticus) fed with oligochitosan remains enigmatic. In this study, the effects of oligochitosan on the growth, immune responses and gut microbes of tilapia were investigated. The feeding trial was conducted in triplicates with the control diet supplemented with oligochitosan at different concentrations (0, 100, 200, 400 or 800 mg/kg). Following a six-week feeding trial, body weights of the fish supplemented with 200 mg/kg and 400 mg/kg oligochitosan were significantly higher than that of the control group. To address the immune responses stimulated by oligochitosan, by the quantitative real time PCR (qRT-PCR), the mRNA expression levels of CSF, IL-1β, IgM, TLR2 and TLR3 genes from head kidney were all significantly up-regulated in the 400 mg/kg group compared to the control. To characterize the gut microbes, bacterial samples were collected from the foregut, midgut, and hindgut, respectively and were subjected to high-throughput sequencing of 16S rDNA. The results showed that significantly lower abundance of Fusobacterium was detected in the hindgut of 400 mg/kg group compared to the control. Additionally, beta-diversity revealed that both gut habitat and oligochitosan had effects on the gut bacterial assembly. To further elucidate the mechanism underlying the effects of oligochitosan on bacterial assembly, the results showed that difference dosages of dietary oligochitosan could alter the specific metabolic pathways and functions of the discriminatory bacterial taxa, resulting in the different bacterial assemblies. To test the antibacterial ability of tilapia fed with oligochitosan, when the tilapias were challenged with Aeromonas hydrophila, the mortality of groups fed with dietary oligochitosan was significantly lower than that of the control. Taken together, appropriate dietary oligochitosan could improve growth, immune responses and alter the bacterial flora in the intestine of tilapia, so as to play a role in fighting against the bacterial infection.

Biomonitoring of Heavy Metal Pollution Using Acanthocephalans Parasite in Ecosystem: An Updated Overview

As a result of the global industrial revolution, contamination of the ecosystem by heavy metals has given rise to one of the most important ecological and organismic problems, particularly human, early developmental stages of fish and animal life. The bioaccumulation of heavy metals in fish tissues can be influenced by several factors, including metal concentration, exposure time, method of metal ingestion and environmental conditions, such as water temperature. Upon recognizing the danger of contamination from heavy metals and the effects on the ecosystem that support life on earth, new ways of monitoring and controlling this pollution, besides the practical ones, had to be found. Diverse living organisms, such as insects, fish, planktons, livestock and bacteria can be used as bioindicators for monitoring the health of the natural ecosystem of the environment. Parasites have attracted intense interest from parasitic ecologists, because of the variety of different ways in which they respond to human activity contamination as prospective indices of environmental quality. Previous studies showed that fish intestinal helminths might consider potential bioindicators for heavy metal contamination in aquatic creatures. In particular, cestodes and acanthocephalans have an increased capacity to accumulate heavy metals, where, for example, metal concentrations in acanthocephalans were several thousand times higher than in host tissues. On the other hand, parasitic infestation in fish could induce significant damage to the physiologic and biochemical processes inside the fish body. It may encourage serious impairment to the physiologic and general health status of fish. Thus, this review aimed to highlight the role of heavy metal accumulation, fish histopathological signs and parasitic infestation in monitoring the ecosystem pollutions and their relationship with each other.

Chitosan from crustacean shell waste and its protective role against lead toxicity in Oreochromis mossambicus

In the current study heavy metal removing capability and antioxidant properties of chitosan supplemented diet tested in lead poisoning induced Oreochromis mossambicus in comparison with and standard fish diet. O. mossambicus fishes weighed (20 ± 2gm) were purchased from a local commercial fish pond and acclimated to the laboratory conditions for 10 days. After that fish were dived into four groups, each group received respective feed throughout the experimental period. The fish fed with standard diet exhibited drastic weakening of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GR), glutathione peroxidase (GPx), ascorbic acid, α- tocopherol and β-carotene and also displayed abnormal histological changes in gills, liver, and intestine. The fish fed with a chitosan supplemented diet for 10 days showed substantial enhancements in antioxidant levels and also normal histological structures of organs in the fish.

Recent progress in biomedical applications of chitosan and its nanocomposites in aquaculture: A review

Chitosan nanoparticles (CSNPs) are the nanostructures of chitosan biopolymer which is derived from chitin polysaccharide, the main component of crustacean shells. Chitosan is a biocompatible, nontoxic and biodegradable polymer soluble in acidic solutions and easily excreted from kidneys. It is widely used in medical and pharmaceutical applications including artificial matrices for tissue engineering, drug transport, targeted drug delivery and protein or gene delivery. The antimicrobial activities of chitosan and CSNPS against different bacterial, fungal and viral pathogens made them valuable for several biological applications including food preservation purposes. In addition, they have immunomodulatory effects on fish and crustaceans providing direct positive impact on aquaculture and fish farming industry. Sustained release of some bioactive ingredients such as hormones, vitamins, nutrients and antioxidants has improved the biological activities of fish. Furthermore, CSNPs have recently been employed to diagnose fish diseases. In this review, we present the medical and biological applications of chitosan and CSNPs on aquatics to provide an update on recent advances and the potential for further advanced applications for aquaculture in the future.

Immunostimulatory effect of dietary chitosan nanoparticles on the performance of Nile tilapia, Oreochromis niloticus (L.)

Feed supplements to fish are generally used to overcome any expected diseases and stressors and to sustain eco-friendly fish farming. One of these feed supplements is chitosan, which stimulated growth and immune properties for many aquatic organisms. It is expected that the nano-sized materials may have stronger immune activation in fish than the ordinary size. Therefore, the current study was conducted to evaluate the effect of dietary chitosan nanoparticles (CNP) on growth performance, antioxidant activity, and innate immunity of Nile tilapia, Oreochromis niloticus (L.). Fish (19.8 ± 0.59 g) were fed on diets enriched with 0.0, 0.25, 0.5, 1.0, and 2.0 g CNP/kg diet for 45 days. Fish performance was significantly improved with increasing CNP levels over the control diet with optimum level of 1.0 g CNP/kg diet. Antioxidant-stimulated activity was observed due to dietary CNP supplementation over the control diet in a dose-dependent manner. However, malondialdehyde level decreased significantly, whereas activities of catalase, superoxide dismutase, lysozyme, and respiratory burst increased significantly due to CNP supplementation in a dose-dependent manner. The current study evoked that dietary CNP showed strong immune modulatory properties and enhanced significantly the performance and health of Nile tilapia with optimum level of 1.0 g CNP/kg diet.

Chitosan nanoparticles: A positive immune response modulator as display in zebrafish larvae against Aeromonas hydrophila infection

Chitosan nanoparticles (CNPs) were synthesized by ionic gelation method and its immunomodulatory properties were investigated in zebrafish larvae. Average particle size and zeta potential were 181.2 nm and +37.2 mv, respectively. Initially, toxicity profile was tested in zebrafish embryo at 96 h post fertilization (hpf) stage using medium molecular weight chitosan (MMW-C) and CNPs. At 5 μg/mL, the hatching rate was almost similar in both treatments, however, the survival rate was lower in MMW-C compared to CNPs exposure, suggesting that toxicity effect of CNPs in hatched larvae was minimal at 5 μg/mL compared to MMW-C. Quantitative real time PCR results showed that in CNPs exposed larvae at 5 days post fertilization (5 dpf) stage, immune related (il-1β, tnf-α, il-6, il-10, cxcl-18b, ccl34a.4, cxcl-8a, lyz-c, defβl-1, irf-1a, irf-3, MxA) and stress response (hsp-70) genes were induced. In contrast, basal or down regulated expression of antioxidant genes (gstp-1, cat, sod-1, prdx-4, txndr-1) were observed. Moreover, zebrafish larvae (at 5 dpf stage) exposed to CNPs (5 μg/mL) showed higher survival rate at 72 h post infection stage against pathogenic Aeromonas hydrophila challenge compared to controls. These results suggest that although CNPs can have toxic effects to the larvae at higher doses, CNPs exposure at 5 μg/mL could enhance the immune responses and develop the disease resistance against A. hydrophila, which could be attributed to its strong immune modulatory properties.

Dietary supplementation of thiamine and pyridoxine-loaded vanillic acid-grafted chitosan microspheres enhances growth performance, metabolic and immune responses in experimental rats

In the present investigation, the effect of dietary supplementation of thiamine and pyridoxine loaded vanillic acid-grafted chitosan microspheres (TPVGC) on growth, metabolic and immune responses in Wistar strain albino rats was studied. Eight experimental groups, namely four groups each for male and female rats were fed with 0, 0.4, 0.8 and 1.6% of TPVGC in the diet. At the end of 45days feeding trials, both male and female rats supplemented with TPVGC had higher weight gain% and specific growth rate than the control groups. Significantly (p<0.05) lower blood glucose level and higher respiratory burst activity were recorded in the treatment groups than the control groups of both male and female rats. Activity of metabolic enzymes (aspartate amino transferase, alanine aminotransferase, alkaline phosphatase and acid phosphatase) and antioxidant enzymes (superoxide dismutase, catalase and glutathione S-transferase) were significantly higher (p<0.05) in the control groups and a decreasing trend in the same was observed with a gradual increase in the inclusion level of TPVGC in the diet of the treatment groups. However, a reverse trend was observed for acetylcholine esterase. It was inferred that dietary supplementation of thiamine and pyridoxine loaded vanillic acid-grafted chitosan enhanced the growth performance, metabolic and immune responses in the animal-model.