Dietary phytoimmunostimulant Persian hogweed (Heracleum persicum) has more remarkable impacts on skin mucus than on serum in common carp (Cyprinus carpio)

Protective effects of Allium jesdianum essential oil on rainbow trout (Oncorhynchus mykiss) exposed to sub-lethal toxicity of cypermethrin

This study aimed to investigate the protective effects of Allium jesdianum essential oil (AJEO) in decreasing cypermethrin toxicity for rainbow trout. First, the safety of the 0%, 0.5%, 1%, and 1.5% AJEO supplements was assayed after 60 days. Then, the protective effects of AJEO were studied on fish exposed to 12.5% 96h LC50 cypermethrin after 14 days. Results showed that 1 and 1.5% AJEO administration enhanced protease and lipase activities in the intestine and improved growth performance. Moreover, feeding fish with 1 and 1.5% AJEO increased catalase (CAT) and superoxide dismutase activities (SOD) and decreased malondialdehyde (MDA). Also, AJEO increased glutathione peroxidase (GPx) activity in serum. However, exposure to cypermethrin significantly decreased these enzyme activities and increased MDA. The oxidative biomarkers remained normal in fish fed with AJEO after exposure to cypermethrin. The administration of 1 and 1.5% AJEO significantly decreased cortisol and glucose levels, alkaline phosphatase (ALP), lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase activities. Although exposure to cypermethrin significantly increased these biochemical biomarkers, AJEO could adjust them. A significant effect of 1% AJEO on total protein and globulin was observed before and after exposure to cypermethrin. Exposure to cypermethrin decreased all immunological parameters in the serum and mucus. However, administration of 1% AJEO increased protease, lysozyme (LYS) activities, total immunoglobulin (Ig), complement C3 and C4, and nitroblue tetrazolium (NBT) in the serum and ALP, LYS, protease activities and Ig in mucus. In conclusion, results showed that AJEO could potentially decrease the toxicity effects of cypermethrin in fish.

Evaluation of the antibacterial activity and protein profiling of Nile tilapia (Oreochromis niloticus) epidermal mucus under different feeds and culture systems (biofloc technology and earthen pond)

The mucus layers of fish serve as the main interface between the organism and the environment. They play an important biological and ecological role. The current study focuses on Nile tilapia epidermal mucus reared under different commercial feeds (coded A and B) and environments (biofloc technology and earthen pond systems). Crude protein levels in feed A and B were 30% and 28%, respectively. Water parameters in all culturing systems were suitable for tilapia throughout the study period. The antimicrobial potency of tilapia (n = 5 from each) epidermal mucus was tested in vitro against human and fish pathogenic strains viz. Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Francisella noatunensis, and Aeromonas hydrophila. To determine the antimicrobial activity, zones of inhibition (ZOI) were measured in millimetres and compared with two antibiotics (chloramphenicol and ciprofloxacin). SDS-PAGE analysis was performed on skin mucus samples of tilapia to determine protein quantity and size (molecular weight). Results of tilapia skin mucus (crude and aqueous) revealed a strong antibacterial effect against all the selected pathogenic strains. However, variation has been observed in the mucus potency and ZOI values between the biofloc and pond tilapia mucus. The crude mucus of tilapia fed on feed A and cultured in the pond exhibited strong antibacterial effects and high ZOI values compared to the mucus of biofloc tilapia, aqueous mucus extracts and positive control chloramphenicol (antibiotic). The SDS-PAGE results showed that the high molecular weight proteins were found in the collected epidermal mucus of BFT-B (240 kDa) and EP-B (230 kDa). Several peptides in fish skin mucus may play a crucial role in the protection of fish against disease-causing pathogens. Thus, it can be utilized in the human and veterinary sectors as an 'antimicrobial' for treating various bacterial infections.

Effects of dietary melatonin on antioxidant and immune function of the Pacific white shrimp (Litopenaeus vannamei), as determined by transcriptomic analysis

Melatonin (MT) is regarded as an antioxidant and immunostimulant that can efficiently scavenge free radicals and activate antioxidant enzymes. The aim of this study was to investigate the effects of dietary MT on the growth performance and immune function of the Pacific white shrimp (Litopenaeus vannamei). Six groups of L. vannamei were supplemented with dietary MT at 0, 22.5, 41.2, 82.7, 165.1, and 329.2 mg/kg levels for 2 months. RNA-Seq analysis was performed to obtain transcriptome data of the control group and the group supplemented with dietary MT at 82.7 mg/kg BW. In total, 1220 DEGs (799 up-regulated and 421 down-regulated) were identified. Pathways and genes related to growth performance and immune function were verified by real-time quantitative polymerase chain reaction. The total hemocyte count, phagocytosis rate, and respiratory burst were significantly increased in the MT (82.7 mg/kg BW) group as compared to the control group. Analysis of antioxidant-related enzymes in the hepatopancreas showed that dietary MT (82.7 mg/kg BW) significantly increased activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, while dietary MT at 41.2 mg/kg BW significantly increased activities of glutathione S-transferase, lysozyme (LZM), and phenoloxidase (PO). At the transcriptional level, dietary MT up-regulated expression levels of genes associated with antioxidant immunity and growth, which included PO, SOD, LZM, GPx, chitin synthase, ecdysone receptor, calcium-calmodulin dependent protein kinase I, and retinoid X receptor. In conclusion, dietary MT may improve the growth performance and immune function of L. vannamei to some extent.

Effect of Different Levels of Chlorogenic Acid on Growth Performance, Immunological Responses, Antioxidant Defense, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss) Juveniles

The current study is designed to assay the efficacy of chlorogenic acid (ChA) in the diet on growth performance, digestive enzyme activity, serum immunological, biochemical, and antioxidant variables, and mucosal immune response as well as disease resistance of rainbow trout (Oncorhynchus mykiss) juveniles. Rainbow trout juveniles received diets supplemented with different inclusion levels of ChA (0 (ctrl), 200 (CA1), 400 (CA2), 600 (CA3), and 800 (CA4) mg kg-1 diet) for 60 days. According to the findings, fish from CA3 and CA4 groups demonstrated the best results considering the final weight (FW) and weight gain (WG) (P < 0.05). Also, the group that received 600 mg kg-1 ChA-supplemented diet showed the lowest feed conversion ratio (FCR) and the highest specific growth rate (SGR) compared to other groups (P < 0.05). Moreover, the minimum survival rate (SR) was only detected in the CA4 treatment (P < 0.05). Regression analysis exhibited that rainbow trout growth indices were polynomially linked to dietary chlorogenic acid concentrations. In this regard, the optimal levels of chlorogenic acid according to growth parameters (FCR and SGR) were 0.71 and 0.62 gr kg-1 diet, respectively. The results exhibited superior performance of protease and amylase activities in CA2, CA3, and CA4 groups with the maximum amount in the group receiving 600 mg kg-1 ChA-enriched diet (P < 0.05). Serum lysozyme (LYZ), immunoglobulin (Ig), and components 3 and 4 (C3 and C4) values of CA2, CA3, and CA4 groups were significantly higher than others with the highest amount in the CA3 group (P <0.05). Additionally, serum nitroblue tetrazolium (NBT) value in the CA3 and CA4 groups and myeloperoxidase (MPO) in the CA3 group were notably more than others (P < 0.05). Moreover, the lowest aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) and the highest total protein (TP) and globulin (GLO) values were observed in CA3 treatment (P < 0.05). CA2 and CA3 groups demonstrated increased serum catalase (CAT) and decreased malondialdehyde (MDA) values compared to the control while the highest CAT and lowest MDA values were observed in CA3 treatment (P < 0.05). Considering mucus immunity, the significantly maximum LYZ and protease values were demonstrated in CA2 and CA3 groups, and the highest ALP, Ig, and esterase values were demonstrated in the CA3 group. In comparison with the control, the mortality rates of the groups that received the ChA diets were remarkably (P < 0.05) lower postchallenge with Y. ruckeri, and the highest survival and relative percentage of survival (RPS) (P < 0.05) belonged to the CA3 group. Results obtained from the current study suggested ChA as a functional dietary additive to raise growth parameters, immune indices, antioxidant capacity, and resistance to disease in rainbow trout.

Heracleum persicum Desf. ex Fisch., C.A.Mey. & Avé-Lall. fruit essential oil: content, antimicrobial activity and cytotoxicity against ovarian cancer cell line

BACKGROUND

One of the most important aromatic species of the Apiaceae family is Heracleum persicum Desf. ex Fisch., C.A.Mey. & Avé-Lall, which used as a spice and condiment in food. It is widely used in traditional Iranian medicine due to its anti-toxic properties. The aim of this study was to evaluate the essential oil of this plant in terms of content and ingredients, cytotoxicity and antimicrobial activity.

METHODS

The fruit of H. persicum was collected in June 2019 from Maragheh region of Kashan, Iran. The essential oil was extracted by water distillation using Clevenger for 3 h. Identification analysis of H. persicum fruit essential oil (HPFEO) components was performed using gas chromatography-mass spectrometry (GC-MS). Evaluation of the effect of the HPFEO on the growth and proliferation of ovarian cancer cell line (OVCAR-3) was performed using MTT colorimetric method. Its antimicrobial activity was evaluated by agar diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal/fungal lethality concentration (MBC/MFC).

RESULTS

The results of analysis of the HPFEO by GC-MS showed that there were 35 compounds with 99.54% relative content. Hexyl butyrate (35.24%), octyl 2-methylbutyrate (11.65%), octyl isobutyrate (9.23%), and octyl acetate (8.42%) were the predominant compounds. Examination of cell survival showed that the viability of cells decreased depending on the concentration of the HPFEO in 24 h and had value of IC50 ~ 12.08 μg/ml against OVCAR-3 cell line. The strongest inhibitory activity of the HPFEO was against Gram-negative bacteria Pseudomonas aeruginosa and Salmonella paratyphi-A serotype (MIC < 62.50 μg/mL). Also, the strong inhibitory and lethal activity of this essential oil against Candida albicans (MIC and MBC 250 μg/mL was one degree weaker compared to nystatin (MIC = 125 μg/mL).

CONCLUSIONS

Thus, HPFEO, in addition to its traditional use, may have a strong and potential potential for the production of anti-proliferative and antimicrobial drugs.

The Probiotic Lactobacillus sakei Subsp. Sakei and Hawthorn Extract Supplements Improved Growth Performance, Digestive Enzymes, Immunity, and Resistance to the Pesticide Acetamiprid in Common Carp (Cyprinus carpio)

This study evaluated the impacts of the probiotic, Lactobacillus sakei (L. sakei), and the extract of hawthorn, Crataegus elbursensis, on growth and immunity of the common carp exposed to acetamiprid. Fish (mean ± SE: 11.48 ± 0.1 g) feeding was done with formulated diets (T ₁ (control): no supplementation, T ₂: 1 × 10⁶ CFU/g LS (Lactobacillus sakei), T3: 1 × 10⁸ CFU/g LS, T ₄: 0.5% hawthorn extract (HWE), and T ₅: 1% HWE) for 60 days and then exposed to acetamiprid for 14 days. The growth performance improved in the fish fed LS at dietary level of 1 × 10⁸ CFU/g, even after exposure to acetamiprid (P < 0.05). Intestinal Lactobacillus sakei (CFU/g) load increased (P < 0.05), following supplementation with the probiotic-enriched diet. The LS-treated fish had increases in the activity of digestive enzymes (P < 0.05). Both LS and HWE stimulated antioxidant enzymes and immune system components in serum and mucus (alkaline phosphatase (ALP), protease, total Ig, and lysozyme) (P < 0.05). However, the changes were different depending on the kind of the supplement. The malondialdehyde (MDA) levels decreased in HWE-treated fish after acetamiprid exposure (P < 0.05). Both LS and HWE reduced the liver metabolic enzymes (LDH, ALP, AST, ALT, and LDH) in serum both before and after exposure to the pesticide (P < 0.05). However, each enzyme exhibited a different change trend depending on the type of the supplement. HWE showed a stress-ameliorating effect, as glucose and cortisol levels declined in the HWE-treated fish (P < 0.05). This study indicated the immunomodulatory impacts of LS (1 × 10⁸ CFU/g) and HWE (at dietary levels of 0.5-1%). The probiotic showed more performance compared to HWE. However, the HWE mitigated oxidative stress more efficiently than the probiotic.

Dietary Chlorella vulgaris mitigated the adverse effects of Imidacloprid on the growth performance, antioxidant, and immune responses of common carp (Cyprinus carpio)

The use of pesticides to eliminate pests and weeds has raised concerns about water pollution and adverse effects on aquatic organisms, so many efforts have been made to increase the resistance of fish to these pesticides by using a proper nutrition strategy. Therefore, the aim of this study is to investigate the growth performance, antioxidant, and immune responses of fish exposed to Imidacloprid insecticide (C9H10ClN5O2) by different doses of Chlorella vulgaris dry powder to the diet of common carp (Cyprinus carpio). In this study, 600 common carp with a medium weight (18.10±0.2 g; Mean ± SE) were prepared and after adaptation and determination of lethal concentration of Imidacloprid, for 56 days in 6 treatments and each with 3 replications were classified and tested (Control (T1), 5% Chlorella vulgaris dry powder and no pollution (T2), 10% Chlorella vulgaris dry powder and no pollution (T3), No Chlorella vulgaris dry powder and 12.5% LC50 Imidacloprid (T4), 5% Chlorella vulgaris dry powder plus 12.5% LC50 imidacloprid (T5) and 10% Chlorella vulgaris dry powder plus 12.5% LC50 Imidacloprid (T6)). After 96 hours of exposure to distinct concentrations of the insecticide, the total mortality was measured and the Imidacloprid median lethal concentration (LC50) over 96 hours was calculated (266.2 mg/l) using Probit analysis. According to the result, common carp fed T2 had the highest final weight (FW), weight gain (WG), and specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among the groups (P<0.05). Fish in the T2 group had the highest Total proteins, Albumin and Globulin (P<0.05). Fish in the group T4 had the highest Cortisol, Lactate Dehydrogenase (LDH), Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), and Alkaline Phosphatase (ALP) levels in the blood, while fish fed T2 and T3 had low values (P<0.05). The Alternative Complement Pathway (ACH50) was significantly higher in T2 and T3 than other groups (P<0.05). Blood total Immunoglobulin (Ig) and Lysozyme activity were high in T2 and T3 groups, and had the lowest values in the T4 group (P<0.05). The Superoxide Dismutase (SOD), Catalase (CAT) and Glutathione Peroxidase (GPx) showed the highest activities in T2 (P<0.05). T4 group had the highest Malondialdehyde (MDA) level, while T2 and T3 groups had the lowest MDA level (P<0.05). The highest Amylase, Protease and Lipase were in the T2 group, while the lowest values were in the T4 group (P<0.05). In conclusion, dietary Chlorella vulgaris protects common carp from Imidacloprid insecticide, since it improved growth performance, antioxidant and immune responses of fish.

Modulatory role of dietary curcumin and resveratrol on growth performance, serum immunity responses, mucus enzymes activity, antioxidant capacity and serum and mucus biochemicals in the common carp, Cyprinus carpio exposed to abamectin

In this study, we investigate the potentials of dietary curcumin and resveratrol on blood biochemistry, immune responses and resistance to the toxicity of the pesticide, abamectin. 540 common carps (30.78 ± 0.17 g) were randomly distributed into 18 tanks (30 fish per tank), as six experimental groups (T1: non-supplemented and on-exposed fish, T2: 300 mg/kg curcumin, T3: 300 mg/kg resveratrol, T4: 12.5% LC₅₀ of abamectin, T5: 300 mg/kg curcumin +12.5% LC₅₀ of abamectin, T6: 300 mg/kg resveratrol + 12.5% LC₅₀ of abamectin). Use of 300 mg/kg resveratrol in the diet of non-abamectin exposed fish improved the growth performance (P < 0.05), while such effects were not observed for curcumin (P > 0.05). There were no differences in the final weight (FW), feed conversion ratio (FCR) and weight gain (WG) between control and fish of the treatments, resveratrol + abamectin and curcumin + abamectin (P < 0.05). The immune components in blood [lysozyme, complement activity, Total immunoglobulin (total Ig), protease, myeloperoxidase (MPO), nitro-blue-tetrazolium (NBT), peroxidase, albumin] and mucus [acid phosphatase (ACP), alkaline phosphatase (ALP), esterase, antiprotease)] and antioxidant enzymes [(superoxide dismutase (SOD), glutathione peroxidase (GPx)] exhibited various change patterns compared to the control group, however, these components were almost all higher in fish supplemented with curcumin and resveratrol in an abamectin-free medium than in control and other groups (P < 0.05). In most cases, the levels of immune and antioxidant components in the control did not show significant difference with the treatments, resveratrol + abamectin and curcumin + abamectin (P > 0.05). Abamectin induced oxidative stress in fish, as the malondialdehyde (MDA) levels significantly increased in the exposed fish compared to non-exposed groups (P < 0.05). It appears that neither curcumin nor resveratrol were as effective in preventing oxidative stress, because MDA levels were higher in exposed fish (abamectin, curcumin + abamectin, resveratrol + abamectin) than in control and non-exposed individuals (P < 0.05). Curcumin and resveratrol also showed protective effects on liver, since the levels of liver metabolic enzymes [aspartate transaminase (AST), ALP, lactate dehydrogenase (LDH)] were lower in the supplemented fish in a abamectin-free medium than in control (P < 0.05). Curcumin and resveratrol also mitigated the stress responses in the exposed fish, as cortisol and glucose levels showed significant decreases in the supplemented fish (P < 0.05). In conclusion, this study revealed that abamectin can depress the growth and immunity in the common carp. Although, both resveratrol and curcumin were mitigated the toxic effects of abamectin, it seems that resveratrol be more effective than curcumin.

Fermented medicinal herbs improve hematological and physiological profile of Striped catfish (Pangasianodon hypophthalmus)

This study sought to determine the effect of fermented medicinal herbs (FMH), i.e. cutchery ( Kaempferia galanga), turmeric ( Curcuma longa) and curcuma ( Curcuma xanthorrhiza) in combination with molasses and probiotic drink (Yakult), administered orally on the hematological and physiological profile of striped catfish ( Pangasianodon hypophthalmus). A complete randomized design (CRD) experiment was used with four levels of treatments, namely P0 (control), P1 (FMH 100 mL/kg), P2 (FMH 200 mL/kg) and P3 (FMH 300 mL/kg) of feed. The fish were kept in a farm in cages at 75 fish/m ³ and fed with the experimental diets for 60 days. The results revealed that FMH (P2) dietary administration improved hematological and physiological profile of catfish, i.e total erythrocytes of 2.81 x 10 ⁶ cells/mm ³, hematocrit values of 39.00%, hemoglobin levels of 10.73 g/dL, total leukocytes of 11.41 x 10 ⁴ cells/mm ³, blood glucose 97.33 mg/dL, and total serum protein 4.10 mg/dL compared to controls with 1.89 x 10 ⁶ cells/mm ³, 32.33 %, g/dL, 9.67 x 10 ⁴ cells/mm ³, 67.33 mg/dL, and total serum protein of 3.10 mg/dL, respectively. Moreover, the diet improved special growth rate, feed conversion ratio, feed efficiency and the survival rate of catfish. The hematological and physiological profile of catfish improvement are considered to be due to the content of secondary metabolites of FMH, namely curcuminoids, vitamin C, essential oils, tannins, and flavonoids, which trigger immunostimulation. The presence of curcuminoids provide an antioxidant effect on cell membranes reducing erythrocyte cell membrane damage due to oxidation. Similarly, flavonoids are natural antioxidants, which are credited with the ability of reducing free radicals and anti-free radicals.

Molecular interaction analysis of β-1, 3 glucan binding protein with Bacillus licheniformis and evaluation of its immunostimulant property in Oreochromis mossambicus

Analyzing the health benefits of any two immunostimulants (synbiotics) in combined form and information on their interactions gain more visibility in the usage of synbiotics in aquafarms. With this intention, the current work explores the immunostimulant effect and structural interaction of synbiotic (β-1, 3 glucan binding protein from marine crab, Portunus pelagicus (Ppβ-GBP) and Bacillus licheniformis) on Oreochromis mossambicus. The experimental diet was prepared with Ppβ-GBP and B. licheniformis, and nourished to the fingerlings of O. mossambicus for 30 days. After the experimental trial, a higher growth rate and immune reactions (lysozyme, protease, myeloperoxidase and alkaline phosphatase activity) were noticed in the fish nourished with synbiotic (B. licheniformis and Ppβ-GBP) enriched diet. Moreover, the synbiotic enriched diet elevated the antioxidant responses like glutathione peroxidase (GSH-Px) and catalase (CAT) activity in the experimental diet-nurtured fish. At the end of the feed trial, synbiotic diet nourished fish shows an increased survival rate during Aeromonas hydrophila infection, reflecting the disease resistance potential of experimental fish. Also, the interaction between Ppβ-GBP and Bacillus licheniformis was analyzed through computational approaches. The results evidenced that, Ppβ-GBP interacts with the B. licheniformis through sugar-based ligand, β-glucan through a hydrogen bond with a good docking score. Thus, the synbiotic diet would be an effective immunostimulant to strengthen the fish immune system for better productivity.

Boesenbergia pandurata application in Goldfish ( Cyprinus carpio) Feed to Enhancing Fish Growth, Immunity System, and Resistance to Bacterial Infection

Background: This study investigated how the inclusion of Boesenbergia pandurata extract (BPE) in goldfish feed affects fish growth, immunity, and resistance to infection by Aeromonas hydrophila and Pseudomonas fluorescens.   Methods: Four fish feeds, were prepared by adding BPE at the concentrations of 0 (control), 2, 4, and 6 g kg-1, respectively, and 120 goldfish (Cyprinus carpio; initial weight 5 g) were separated into 12 boxes and fed with specific pellets and examined thrice. The experiment lasted 12 weeks, beginning with the different feeds, fish growth was measured at Weeks 4 and 8 after the feeding period. Moreover, a challenge test with pathogen bacteria to assay disease resistance was administered at Week 8 after the feeding period, and the survival rate and relative percentage of survival were quantified at Week 12.   Results: At Week 8, the goldfish that were fed BPE-containing feeds were significantly heavier than the fish that received the control feed (pellet without BPE), and the highest weight gain, reaching 72.44 g, was obtained with Pellet 3; accordingly, the specific growth rate after BPE treatment (5.7%) was higher than that after control treatment. Conversely, the feed conversion ratio in the control group, 2.03, was higher than the ratios in the BPE groups, which were decreased to 0.55-0.90. Lastly, BPE treatment consistently enhanced the immunity parameters of goldfish (relative to control treatment) at weeks 4 and 8, and following BPE treatment, the rate of resistance against bacterial infection, 68.3%-77.0%, was higher than that after control treatment.   Conclusions: BPE addition in goldfish feed clearly produces a positive effect by enhancing fish growth, immunity, and resistance to infection by pathogenic bacteria, and 4 g kg-1 is the optimal BPE concentration in feed prepared for goldfish.

Boesenbergia pandurata application in Goldfish ( Cyprinus carpio) Feed to Enhancing Fish Growth, Immunity System, and Resistance to Bacterial Infection

Background: This study investigated how the inclusion of Boesenbergia pandurata extract (BPE) in goldfish feed affects fish growth, immunity, and resistance to infection by Aeromonas hydrophila and Pseudomonas fluorescens.   Methods: Four fish feeds, were prepared by adding BPE at the concentrations of 0 (control), 2, 4, and 6 g kg-1, respectively, and 120 goldfish (Cyprinus carpio; initial weight 5 g) were separated into 12 boxes and fed with specific pellets and examined thrice. The experiment lasted 12 weeks, beginning with the different feeds, fish growth was measured at Weeks 4 and 8 after the feeding period. Moreover, a challenge test with pathogen bacteria to assay disease resistance was administered at Week 8 after the feeding period, and the survival rate and relative percentage of survival were quantified at Week 12.   Results: At Week 8, the goldfish that were fed BPE-containing feeds were significantly heavier than the fish that received the control feed (pellet without BPE), and the highest weight gain, reaching 72.44 g, was obtained with Pellet 3; accordingly, the specific growth rate after BPE treatment (5.7%) was higher than that after control treatment. Conversely, the feed conversion ratio in the control group, 2.03, was higher than the ratios in the BPE groups, which were decreased to 0.55-0.90. Lastly, BPE treatment consistently enhanced the immunity parameters of goldfish (relative to control treatment) at weeks 4 and 8, and following BPE treatment, the rate of resistance against bacterial infection, 68.3%-77.0%, was higher than that after control treatment.   Conclusions: BPE addition in goldfish feed clearly produces a positive effect by enhancing fish growth, immunity, and resistance to infection by pathogenic bacteria, and 4 g kg-1 is the optimal BPE concentration in feed prepared for goldfish.

Evaluation of the Inclusion of the Green Seaweed Ulva ohnoi as an Ingredient in Feeds for Gilthead Sea Bream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

Simple Summary

The use of seaweeds in aquafeeds is receiving increasing attention due to their potential nutritional and functional benefits. However, several green seaweeds such as Ulva presents nutritional limitations because of the undigestible polysaccharides, although these may exert a positive effect on the immunological status of the fish. The present study developed three different experiments aimed to re-evaluate the presence of protease inhibitors described for Ulva ohnoi, to assess its nutritional value as an ingredient and also to evaluate its potential protective effect on the oxidative metabolism of fish, being experiments developed in two different fish species (European sea bass Dicentrarchus labrax and gilthead sea bream, Sparus aurata). Results indicate the absence of negative effects of U. ohnoi on protein digestion of sea bream but a limited value as a feed ingredient. In contrast, its contents in bioactives seem to be correlated to the observed positive effects on the immune status and oxidative metabolism when fish are challenged by the consumption of highly oxidized dietary oil.

Abstract

This study evaluated the use of Ulva ohnoi as an ingredient in feeds for aquaculture in three different experiments. Experiment 1 was oriented to confirm the negative effect of U. ohnoi on fish digestion. Experiment 2 assessed the effect on growth, feed efficiency, and immune status of juvenile sea bass (Dicentrarchus labrax) fed on diets including U. ohnoi, previously treated or not with carbohydrases used to partially hydrolyze indigestible polysaccharides. Experiment 3 was aimed to evaluate the potential protective effect of U. ohnoi on the oxidative status of sea bream (Sparus aurata) challenged by the consumption of a feed formulated with the oil fraction completely oxidized. Results show a negligible effect of U. ohnoi meal on protein digestion when included in feeds at levels of 10% or less. Moreover, results of growth and feed use evidenced the possibility of using up to 5% inclusion of algal meal in feeds without adverse effects on the zootechnical parameters, while the enzyme pretreatment was ineffective to improve its nutritional use. Finally, the inclusion of U. onhoi in feeds determined both an immunostimulatory effect, evidenced by an increase in skin mucus lysozyme in the two mentioned fish species, and a positive influence on the oxidative metabolism of seabream when fed on a diet including rancid oil.

Effect of Fortified Feed with Phyto-Extract on the First Physical Barrier (Mucus) of Labeo rohita

Simple Summary

Pathogens of fish are a serious issue faced by farmers and a great threat to the country’s economy. Overuse of antibiotics leads to antibiotic-resistant strains of the bacterial pathogens; residues of the antibiotics also accumulate in the tissue of the fish and are responsible for environmental problems. Therefore, the use of antibiotic alternatives should be explored as a new approach to immunotherapy to prevent or to cure preexisting infections. Previous research has concluded that the use of herbal extracts enhances the immunity of fish against several fish pathogens such as bacteria and other protozoon parasites. This study aimed to evaluate the effect of two different fortified feeds with different concentrations of Withania coagulans and Zingiber officinale on the fish mucus of Labeo rohita. The mucus was tested against five pathogenic bacteria in-vitro while fish was tested against the ectoparasite Lernaea (in-vivo). Our result showed that Z. officinale proves an efficient immune stimulator for the L. rohita against the tested organism (both in vivo and in vitro). Hence, it can be used as an effective solution against the emerging diseases of cultured fish.

Abstract

The aim of the current study was to assess the effect of two different fortified feeds with different concentrations of two important medicinal plants (Withania coagulans and Zingiber officinale) on the mucosal immunity of Labeo rohita. After a dietary intervention, mucus was tested against five pathogenic bacteria (in-vitro), while experimental fish were tested against the ectoparasite (Lernaea) (in-vivo). Our results revealed that all fish groups fed with different concentrations (1, 1.5, and 2%) of Z. officinale had low molecular weight proteins and did not develop any significant signs of parasitic infection, with low mortality rate; whereas the groups that were fed with W. coagulans (particularly with 1% and 2%), including a control group, developed rapid signs of infection with high mortality rate. The highest hemagglutination titer value was recorded for the fish fed with 1% and 1.5% of Z. officinale. The lowest value was found for the fish fed with 2% of W. coagulans. The mucus of all fish of fortified groups was active and inhibited the growth of tested bacterial pathogens as compared to the control group. Further, Z. officinale groups showed greater efficacy against bacteria as compared to the W. coagulans groups. In conclusion, Z. officinale can be considered as a potential and functional ingredient in aquaculture feed. Furthermore, future studies should be conducted to investigate more details on the subject.

Extract of grape seed enhances the growth performance, humoral and mucosal immunity, and resistance of common carp (Cyprinus carpio) against Aeromonas hydrophila

This study evaluated the effects of grape seed extract (GSE) on the growth performance, immune response, and disease resistance of common carp (Cyprinus carpio). Fish were distributed in four groups and fed diets with varying levels of GSE at 0, 10, 20, and 30 g/kg for 56 days. The final length in fish fed with 20 and 30 g GSE/kg diet significantly increased in comparison with the control group (P<0.05). The final weight and weight gain of fish fed with GSE were statistically higher than for the control diet, while the feed conversion ratio was lower in GSE groups than the control. Hematological parameters did not statistically improve with GSE supplemented diets (P>0.05). However, fish fed with 30 g GSE/kg diet displayed a significantly higher WBC count than the other group (P<0.05). The serum total protein and globulin in fish fed with 20 g GSE/kg diet significantly increased compared to the control (P<0.05). A similar pattern was noticed in results for serum and mucus lysozyme activity with a significant increase in fish fed with 20 and 30 g GSE/kg diet compared to the control (P<0.05). Total antibody levels in serum and mucus samples were also increased in fish by dietary GSE with maximum levels by 20 and 30 g GSE/kg diet. Besides, mucus protease activity was higher in fish that received 20 and 30 g GSE/kg diet with maximum level shown in fish fed with 30 g GSE/kg diet compared to the control group (P<0.05). Meanwhile, all groups showed higher mucus antibacterial activity against Aeromonas hydrophila with the highest activity in 30 g GSE/kg diet in comparison with the control group. The cumulative mortality was 36.67% when fish were fed with 30 g GSE/kg diet and challenged with A. hydrophila. However, the mortality rate was 40% and 53.33% in fish fed 20 and 30 g GSE/kg diet, respectively. This study suggests that supplementation of GSE could significantly enhance the growth performance, immune responses, and disease resistance against A. hydrophila in common carp.

Effects of dietary fern (Adiantum capillus-veneris) leaves powder on serum and mucus antioxidant defence, immunological responses, antimicrobial activity and growth performance of common carp (Cyprinus carpio) juveniles

A 56-day research was performed to examine the influence of graded levels (0 (control), 0.5, 1 and 2%) of Fern (Adiantum capillus-veneris) leaves powder (FLP) in diet on immune competence and growth of common carp (Cyprinus carpio, initial weight = 20 g). The serum total immunoglobulins content and lysozyme activity in the 1 and 2% FLP groups remarkably increased compared to the other groups (P < 0.05). The skin mucosal lysozyme activity enhanced with increasing dietary FLP level in a dose-response manner. Fish fed on the FLP-supplemented diets had higher skin-mucosal superoxide dismutase activity than the control (P < 0.05). However, serum antioxidant enzymes were not affected by dietary fern (P > 0.05). The serum bactericidal activity against human and fish pathogens increased with enhancing the FLP level in diet against Staphylococcus aureus, Escherichia coli (EHEC ATCC 43895), Escherichia coli (CI), Pseudomonas aeruginosa, Klebsiella pneumonia and Aeromonas hydrophila. The serum antibacterial activity against Yersinia ruckeri in the 2% FLP group was higher than the other treatments. Furthermore, the serum bactericidal activity against P. aeruginosa (ATCC 27853) only observed in fish fed on the 1 and 2% FLP-supplemented diets. The skin mucosal bactericidal activity and inhibitory effects increased with enhancing the FLP level in diet against E. coli, K. pneumonia, Y. ruckeri and A. hydrophila in a dose response manner. Moreover, the skin mucosal bactericidal activity against S. aureus only observed in fish fed on 1 and 2% FLP-supplemented diets. The weight gain values in the 1 and 2% FLP groups were higher than the other treatments (P < 0.05). Feed conversion ratio (FCR) improved with increasing FLP level in diet in a dose-response manner (P < 0.05). By considering serum and mucosal bactericidal activities against different pathogenic bacteria, the supplementation of 2% FLP in diet is recommended for C. carpio during grow-out phase.

How do essential oil composition and phenolic acid profile of Heracleum persicum fluctuate at different phenological stages?

Heracleum persicum, commonly named Persian hogweed, is a principal native medicinal plant in Iran. Collecting H. persicum at the most appropriate growing stage is the key factor to achieve the high phytochemical quality to meet consumer's needs. In the present experiment, the aerial parts of this plant were harvested at up to six different developmental stages during the growing season to determine the phytochemical profiles. Our results indicated that the highest essential oil content was obtained in the mid-mature seed stage (3.5%). The most elevated extract content was recorded in the floral budding stage (10.4%). In the vegetative stage, limonene (18.1%), in floral budding stage, caryophyllene (14.1%), anethole (14.6%), and β-bisabolene (12.7%), in the full flowering stage, myristicin (15.0%), and hexyl butyrate (9.1%), in the early development of seeds stage, hexyl butyrate (32.1%), and octyl acetate (11.7%), in the mid-mature seeds stage hexyl butyrate (38.8%), octyl acetate (14.5%), in the late-mature/ripe seeds stage, hexyl butyrate (23.6%), and octyl acetate (10.5%) are recorded as the main components. The highest phenolic acids content was obtained in the floral budding stage (287.40 mg/g dried extract). The analysis of phenolic acids demonstrated cinnamic acid (8.0-225.3 mg/g extract), p-coumaric acid (1.7-39.2 mg/g extract), p-hydroxybenzoic acid (0.8-16.8 mg/g extract), and ferulic acid (2.4-15.8 mg/g extract) as the main phenolic acids. Cinnamic acid was found as the major phenolic compound in the vegetative stage following by floral budding, the full flowering stage, the early development of seeds, and late-mature/ripe seeds stages. P-coumaric acid was the most abundant phenolic compounds in the mid-mature seeds stage. In this regard, the harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest. The results of this study can be used as a guideline for grower to obtain the highest possible amount of desirable metabolites, beneficial in both food and pharmaceutical industries as well as their undeniable economical benefits.

Skin Mucosal, Serum Immunity and Antioxidant Capacity of Common Carp (Cyprinus carpio) Fed Artemisia (Artemisia annua)

In this study, the effect of artemisia (Artemisia annua) leaves extract (ALE) on the immune system, growth performance and antioxidant capacity of common carp (Cyprinus carpio) was investigated. Fish with initial weight (90.32 ± 1.12 g) were fed various levels of ALE (0, 0.5, 1 and 1.5 g/kg) for 8 weeks. The results showed that the growth performance (FW, WG, SGR, PER, and LER) in fish fed 1 g/kg ALE was increased significantly (P<0.05) and the feed conversion ratio (FCR) was improved in fish fed 1 and 1.5 g/kg ALE in comparison to the control group (P<0.05). Skin mucus total protein was higher in fish fed diet containing 0.5 g/kg ALE than the other experimental groups (P<0.05), while the lysozyme, immunoglobulin and protease was increased by increasing of ALE in diets. Respiratory burst activity and serum immune parameters were higher in fish fed 0.5 g/kg ALE than the other treatments (P<0.05). Increasing of catalase (CAT) and decreasing of malondialdehyde (MDA) were observed in fish fed ALE, while glutathione peroxidase (GPx) increased only in fish fed 0.5 g/kg ALE. Hence, it can be concluded that ALE has considerable potential as a natural immunostimulant and growth promotor supplement for the common carp’s aquaculture.

Dietary supplementation of drumstick tree, Moringa oleifera, improves mucosal immune response in skin and gills of seabream, Sparus aurata, and attenuates the effect of hydrogen peroxide exposure

In aquatic animals, the mucosal barrier is the first line of innate immune defence against external chemicals and pathogens. In this study, the effects of dietary Moringa oleifera leaf (MOL) supplementation on skin and gill mucosal immunity, antioxidants and stress responses were evaluated in seabream (Sparus aurata) fingerlings exposed to hydrogen peroxide (H₂O₂). A total of 144 specimens (10.11 ± 0.41 g) were divided into four treatments (three replicates per treatment contained 12 specimens each) and fed a non-supplemented control diet or a 1, 2.5 or 5% MOL-supplemented diet. After three weeks of feeding, six specimens from each aquarium were sampled for blood, mucus and tissues. The other six fish in each aquarium were subjected to H₂O₂ exposure. The results revealed that MOL did not negatively affect either cortisol or glucose levels. MOL supplementation significantly (P < 0.05) improved skin mucosal immunity-related characteristics, including phosphatase, peroxidase and lysozyme activity and IgM levels. Additionally, MOL upregulated the expression of antioxidant genes (sod and cat), an anti-inflammatory gene (tgf-β), tight junction protein genes (occludin and zo-1), c3, and igm in both the skin and gills. However, H₂O₂ exposure significantly (P < 0.05) increased both cortisol and glucose levels and disrupted skin mucosal immune function by significantly (P < 0.05) decreasing phosphatase, peroxidase, protease, antiprotease and lysozyme activity and IgM levels. H₂O₂ exposure severely decreased the mRNA levels of the studied genes. MOL dietary supplementation at the 5% level successfully attenuated the negative effects of H₂O₂ on the mucosal immune response in both the skin and gills. In conclusion, dietary MOL supplementation at the 5% level is recommended to improve S. aurata mucosal immune function under both normal and stress conditions. Additionally, exposure to H₂O₂ disrupts the mucosal immunity of fish. This contributes knowledge on the routes involved in mucosal innate immunity and could help to understand the fish resistance against chemicals exposure. Graphical abstract.

The Effects of Oral Rehmannia glutinosa Polysaccharide Administration on Immune Responses, Antioxidant Activity and Resistance Against Aeromonas hydrophila in the Common Carp, Cyprinus carpio L

The effects of the oral administration of Rehmannia glutinosa polysaccharide (RGP-1) on the immunoregulatory properties, antioxidant activity, and resistance against Aeromonas hydrophila in Cyprinus carpio L. were investigated. The purified RGP-1 (250, 500, and 1,000 μg/mL) was co-cultured with the head kidney cells of the common carp. The proliferation and phagocytosis activities of the head kidney cells, and the concentration of nitric oxide (NO) and cytokines in the culture medium were determined. Next, 300 common carps (47.66 ± 0.43 g) were randomly divided into five groups; the two control groups (negative and positive) were administered sterile PBS and the three treatment groups were administered different concentrations of RGP-1 (250, 500, and 1,000 μg/mL) for seven days. Subsequently, the positive and treatment groups were infected with A. hydrophila, and the negative group was administered sterile PBS for 24 h. The concentration of NO, cytokines, lysozyme (LZM), and alkaline phosphatase (AKP) in serum, the total antioxidant capacity (T-AOC), the levels of malonaldehyde (MDA) and glutathione (GSH), and the total activities of superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the hepatopancreas of the common carp were tested. We observed that RGP-1 could significantly enhance the proliferation and phagocytosis activities (P < 0.05), besides inducing the production of NO, pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12) and anti-inflammatory cytokines (IL-10, TGF-β) (P < 0.05) in vitro. The in vivo experimental results revealed that RGP-1 significantly enhanced NO production, protein levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12), LZM and AKP activities, and the antioxidant content (T-AOC, SOD, CAT, GSH, GSH-Px, and MDA) compared to that observed in the negative group prior to A. hydrophila infection (P < 0.05). NO, pro-inflammatory cytokines, LZM and AKP activities were significantly lower than that in the positive group after infection (P < 0.05). However, whether infected or not, the expression of anti-inflammatory cytokines (IL-10, TGF-β) increased significantly in the RGP-1-treated groups (P < 0.05). Therefore, the results suggested that RGP-1 could enhance the non-specific immunity, antioxidant activity and anti-A. hydrophila activity of the common carp, and could be used as a safe and effective feed additive in aquaculture.

Humoral and skin mucosal immune parameters, intestinal immune related genes expression and antioxidant defense in rainbow trout (Oncorhynchus mykiss) fed olive (Olea europea L.) waste

A six-week feeding trial was carried out to evaluate the effects of inclusion of dietary olive waste cake (OWC, 0, 0.5, 2.5 and 5 g kg^-1 diet) on performance, antioxidant condition and immune responses of rainbow trout (Oncorhynchus mykiss) (2.5 ± 0.1 g). Supplementing diet with 2.5 and 5 g OWC kg^-1 diet significantly enhanced serum and mucosal lysozyme activity in fish. Regarding mucosal immunity, fish fed 2.5 and 5 g OWC kg^-1 diets had higher skin mucus total Ig concentrations than other groups. In relation to antioxidant status, those in 2.5 g OWC kg^-1 and the control groups exhibited the highest and the least liver superoxide dismutase and glutathione peroxidase activities, respectively. Furthermore, the activity of liver glutathione S transferase in fish fed 2.5 and 5 g OWC kg^-1 diets was higher than the other treatments. In respect to gut cytokines gene expression, our findings demonstrated dietary OWC did not influence interlukines-1β and 10 genes expression, but relative expression of IL8 gene gradually up-regulated with increasing dietary OWC level. Moreover, fish fed 0.5 g OWC kg^-1 and the control diets had the highest and the lowest gut tumor necrosis factor-α gene expression values, respectively. The relative expression of transforming growth factor-β significantly down-regulated in gut of fish fed 2.5 and 5 g OWC kg^-1 diets compared to other groups. Supplementing diet with OWC pronouncedly improved growth and feed conversion ratio in fish compared to the control. Overall, the findings of this study suggested that inclusion of 2.5 g OWC kg^-1 diet can improve growth rate, oxidative stress status, humoral and skin mucosal immune responses in O. mykiss fingerlings and it can be considered as a functional feed additive for this species.

Bioprospection of biocompounds and dietary supplements of microalgae with immunostimulating activity: a comprehensive review

The objective of this review is to analyze the role of microalgal bioprospecting and the application of microalgae as food supplements and immunostimulants in global and regional aquaculture, highlighting the Brazilian Amazon. This study evaluates the primary advantages of the application of the bioactive compounds of these microorganisms, simultaneously identifying the knowledge gaps that hinder their biotechnological and economic exploitation. The methodology used is comparative and descriptive-analytical, considering the hypothesis of the importance of bioprospecting microalgae, the mechanisms of crop development and its biotechnological and sustainable application. In this context, this review describes the primary applications of microalgae in aquaculture during the last decade (2005–2017). The positive effects of food replacement and/or complementation of microalgae on the diets of organisms, such as their influence on the reproduction rates, growth, and development of fish, mollusks and crustaceans are described and analyzed. In addition, the importance of physiological parameters and their association with the associated gene expression of immune responses in organisms supplemented with microalgae was demonstrated. Complementarily, the existence of technical-scientific gaps in a regional panorama was identified, despite the potential of microalgal cultivation in the Brazilian Amazon. In general, factors preventing the most immediate biotechnological applications in the use of microalgae in the region include the absence of applied research in the area. We conclude that the potential of these microorganisms has been relatively well exploited at the international level but not at the Amazon level. In the latter case, the biotechnological potential still depends on a series of crucial steps that involve the identification of species, the understanding of their functional characteristics and their applicability in the biotechnological area, especially in aquaculture.

Skin mucus metabolites in response to physiological challenges: A valuable non-invasive method to study teleost marine species

Knowledge concerning the health and welfare of fish is important to conserve species diversity. Fish mucosal surfaces, and particularly the skin, are of utmost importance to protect the integrity and homeostasis of the body and to prevent skin infections by pathogens. We performed three trials simulating different environmental and anthropogenic challenges: fish capture (air exposure), bacterial infection and fasting, with the aim of evaluating epidermal mucus as a non-invasive target of studies in fish. In this initial approach, we selected three well-known marine species: meagre (Argyrosomus regius), European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) for our study. Mucus viscosity was measured in order to determine its rheological properties, and mucus metabolite (glucose, lactate, protein and cortisol) levels were analysed to establish their suitability as potential biomarkers. Skin mucus appeared as a viscous fluid exhibiting clearly non-Newtonian behaviour, with its viscosity being dependent on shear rate. The highest viscosity (p < 0.05) was observed in sea bream. Mucus metabolites composition responded to the different challenges. In particular, glucose increased significantly due to the air exposure challenge in meagre; and it decreased during food deprivation in sea bream by a half (p < 0.05). In contrast, mucus protein only decreased significantly after pathogenic bacterial infection in sea bass. In addition, mucus lactate immediately reflected changes closely related to an anaerobic condition; whereas cortisol was only modified by air exposure, doubling its mucus concentration (p < 0.05). The data provided herein demonstrate that mucus metabolites can be considered as good non-invasive biomarkers for evaluating fish physiological responses; with the glucose/protein ratio being the most valuable and reliable parameter. Determining these skin mucus metabolites and ratios will be very useful when studying the condition of critically threatened species whose conservation status prohibits the killing of specimens.

Modulation of rainbow trout (Oncorhynchus mykiss) cutaneous mucosal immune responses following anesthesia: A comparative study on different anesthetic agents

The present study investigated the possible effects of different anesthetic agents including MS222 (50 ppm), 2-Phenoxyethanol (2-PE) (0.2 mL L^-1) and clove oil (25 ppm), on cutaneous mucosal immune parameters in rainbow trout (Oncorhynchus mykiss). The induction and recovery times for each anesthetic agent were assessed. Also, the immune parameters were measured in skin mucus, 1 and 24 h post anesthesia. No significant difference was observed among treatments at 1 h post-anesthesia except for bactericidal and alkaline phosphatase (ALP) activities which was significantly enhanced in fish exposed to 2-PE compared to other anesthetics. At 24 h post-anesthesia, most of the skin mucosal immune parameters were increased upon exposure to clove oil but decreased following exposure to 2-PE. However, no significant change was noticed after MS222 exposure. These results demonstrated that the anesthetics type should be considered to avoid possible immunosuppression in farmed fish. Furthermore, the present results could be useful for better understanding of alterations in cutaneous mucosal immunity in response to chemical stressors such as anesthetic agents.

Effects of dietary inclusion of Moringa oleifera leaves on growth and some systemic and mucosal immune parameters of seabream

The effect of the dietary incorporation of drumstick, Moringa oleifera, leaf meal (MOL; 0, 5, 10 and 15%) on the growth, feed utilization, some skin mucus and systemic immune parameters and intestinal immune-related gene expression in gilthead seabream (Sparus aurata) specimens. The experiment lasted 4 weeks. The results revealed that MOL can be incorporated in S. aurata diet up to 10% with no significant negative effect on growth and feed utilization. However, there was a significant decrease with MOL at a level of 15% after 2 weeks of feeding. The systemic immune status of fish fed with the different levels of MOL showed an improvement in head kidney leucocyte phagocytosis, respiratory burst and peroxidase activities. Also, serum humoral components, including protease, ACH₅₀ and lysozyme activities and IgM level, increased with MOL inclusion especially at the 5% level. MOL at 5% improved skin-mucosal immunity such as protease, antiprotease, peroxidase and lysozyme activities. Moreover, the feeding of MOL revealed an upregulation of the intestinal mucosal immunity genes (lyso and c3), tight junction proteins (occludin and zo-1) and anti-inflammatory cytokines (tgf-β) with a downregulation of pro-inflammatory cytokine (tnf-α). Therefore, it is recommended to incorporate MOL in S. aurata diets at a level of 5% for the best immune status or 10% for the high growth performance and acceptable immune surveillance. Graphical abstract ᅟ.

Enrichment of common carp (Cyprinus carpio) diet with medlar (Mespilus germanica) leaf extract: Effects on skin mucosal immunity and growth performance

A feeding trial was performed to assess the effects of dietary Medlar (Mespilus germanica) leaf extract (MLE) on the growth performance, skin mucus non-specific immune parameters as well as mRNA levels of immune and antioxidant related genes in the skin of common carp (Cyprinus carpio) fingerlings. Fish were fed diets supplemented with graded levels (0, 0.25, 0.50, and 1.00%) of MLE for 49 days. The results revealed an improvement to the growth performance and feed conversion ratio in MLE fed carps (P < 0.05), regardless of the inclusion level. The immunoglobulin levels and interleukin 8 levels in the skin mucous and skin, respectively, revealed significant increment in fish fed 1% MLE (P < 0.05) in comparison with the other MLE treatments and control group. Also, feeding on 0.25% and 0.50% MLE remarkably increased skin mucus lysozyme activity (P < 0.05). However, there were no significant difference between MLE treated groups and control (P > 0.05) in case protease activity in the skin mucous or tumor necrosis factor alpha and interleukin 1 beta gene expression in the skin of carps (P > 0.05). The expression of genes encoding glutathione reductase and glutathione S-transferase alpha were remarkably increased in MLE fed carps compared to the control group (P < 0.05) while carp fed 0.50% or 1.00% MLE had significantly increased glutathione peroxidase expression in their skin (P < 0.05). The present results revealed the potentially beneficial effects of MLE on the mucosal immune system and growth performance in common carp fingerlings.

The effects of dietary Myrtle (Myrtus communis) on skin mucus immune parameters and mRNA levels of growth, antioxidant and immune related genes in zebrafish (Danio rerio)

Myrtle (Myrtus communis L., Myrtaceae) is a significant plant which naturally distributed around the globe. Although numerous studies have demonstrated the benefits of myrtle in different species, studies using the oral route are rare in the literature. In the present study, we evaluated the effect of myrtle intake on the antioxidant, immune, appetite and growth related genes as well as mucosal immune responses in zebrafish (Danio rerio) model. Zebrafish were fed control or myrtle (5, 10 and 20 g kg^-1 myrtle) supplemented diets for sixty days. The results showed that, oral administration of Myrtle significantly improved mucosal immune responses (the activity of lysozyme, total Ig and protease). Furthermore, fish fed 20 g kg^-1 showed remarkably higher antioxidant (sod and cat) enzymes gene expression compared other treatment. There were significant difference between myrtle fed fish and control group regarding tnf-alpha and lyz expression. Also, evaluation of growth (gh and igf1) related genes revealed remarkable upregulation in 20 g kg^-1 myrtle treatment compared other myrtle treatments and control group. Similar results was observed regarding the mRNA levels of appetite related genes (ghrl) in zebrafish fed 20 g kg^-1 myrtle. The present results indicated that dietary administration of myrtle improved mucosal immune parameters and altered mRNA levels of selected genes. These results on zebrafish model also highlights the potential use of Myrtle supplements as additive in human diets.

Dietary Myrtle (Myrtus communis L.) improved non-specific immune parameters and bactericidal activity of skin mucus in rainbow trout (Oncorhynchus mykiss) fingerlings

The present study examined the effects of dietary Myrtle (Myrtus communis L.) on non-specific immune parameters and bactericidal activity of skin mucus in rainbow trout (Oncorhynchus mykiss) fingerlings. Three hundred and sixty fingerlings (6.50 ± 0.55 g (were distributed in twelve cages (65 × 65 × 65 cm) with a metal framework. The study included four treatments repeated in triplicates. The treatments were feeding trouts with experimental diets containing different levels (0, 0.5, 1 and 1.5%) of Myrtle powder. The fingerlings were fed on experimental diet for sixty days and then skin mucus non-specific immune parameters as well as bactericidal activity were measured. At the end of the trial, the highest skin mucus soluble protein level was observed in group fed with 1.5% Myrtle (P < 0.05). The alkaline phosphatase (ALP) activity was significantly increased in fish groups fed 1 and 1.5% Myrtle compared with the control group (P < 0.05). However, evaluation of skin mucus lysozyme activity showed no significant difference between treatments and control group (P > 0.05). Also, no antibacterial activity was detected against Escherichia coli, Staphylococcus aureus and Salmonella enterica in all treatments and control group. Whereas skin mucus of rainbow trout showed antimicrobial activity against fish pathogens (Aeromonas hydrophila and Yersinia ruckeri) in 1 and 1.5% Myrtle treatments. These results indicated beneficial effects of dietary Myrtle on mucosal immune parameters of fingerling rainbow trout.