Humoral immune parameters of cultured Atlantic halibut (Hippoglossus hippoglossus L.)

Inclusion Effect of Various Levels of Jack Mackerel Meal in Olive Flounder (Paralichthys olivaceus) Diets Substituting 50% Fish Meal with Duck By-Product Meal on Growth and Feed Utilization

This experiment was performed to evaluate the inclusion impact of various levels of jack mackerel meal (JMM) in olive flounder (P. olivaceus) feeds substituting 50% FM by duck by-product meal (DBM) on growth, feed availability, and economic efficiency. Seven experimental diets were prepared. The control (Con) diet contained 60% FM. Fifty percent FM in the Con diet was substituted with DBM, and then the graded levels (0%, 10%, 20%, 30%, 40%, and 50%) of JMM were added instead of FM, named the DJ0, DJ10, DJ20, DJ30, DJ40, and DJ50 diets, respectively. All feeds were assigned to triplicate fish groups. At the end of 56 days' feeding, fish fed the DJ40 and DJ50 diets exhibited comparable weight gain and specific growth rate to fish fed the Con diet. Higher feed consumption was observed in fish fed the Con, DJ40, and DJ50 diets compared to fish fed the DJ0 and DJ10 diets. Lower feed conversion ratio was observed in fish fed the Con diet compared to fish fed the DJ0, DJ10, DJ20, and DJ30 diets. Furthermore, the DJ50 diet led to the highest economic profit index (EPI). In conclusion, inclusion of 50% JMM in the olive flounder diet replacing 50% FM with DBM seems to be the most recommendable dietary treatment based on growth and feed consumption of olive flounder and EPI.

Impact on Growth and Feed Availability from Including Jack Mackerel (Trachurus japonicas) Meal in Rockfish (Sebastes schlegeli) Feeds Which Otherwise Replace Fish Meal with Chicken By-Product Meal

This study was conducted to elucidate the impact on the growth and feed availability of rockfish (Sebastes schlegeli) from including jack mackerel meal (JMM) in feeds which otherwise substitute 20% fish meal (FM) with chicken by-product meal (CBM). Six formulated feeds were designed to be isonitrogenous and isolipidic. Specifically, 55% FM was included in the control (Con) diet. In the Con diet, 20% FM was substituted by CBM, and then the graded levels (0, 20, 40, 60, and 80%) of JMM were included instead of FM, named as the C20J0, C20J20, C20J40, C20J60, and C20J80 diets, respectively. Five hundred and forty juvenile rockfish (initial weight of 11.2 g) were assigned to 18 tanks. All experimental feeds were fed to triplicate groups of rockfish twice daily for 8 weeks. Superior weight gain, specific growth rate (SGR), and feed intake of rockfish fed the C20J60 and C20J80 diets compared to rockfish fed the Con and C20J0 diets were observed. However, the feed utilization, biological indices, proximate composition, amino acid profiles, and blood chemistry of the rockfish were not affected by the dietary treatments. The slightly but not significantly higher economic profit index and growth performance were obtained in the C20J60 diet compared to the C20J80 diet. In conclusion, the C20J60 diet was the most recommendable treatment based on the improvement in growth performance (weight gain and SGR) and feed intake of rockfish, and the highest economic return to farmers.

Fish Meal Substitution Effects with the Combined Animal Proteins in the Feeds of Olive Flounder (Paralichthys olivaceus) on Growth Performance, Feed Availability, and Disease Resistance against Streptococcus iniae

This study aims to reveal the substitution impact of fish meal (FM) with the combined meat meal and chicken by-product meal (CMC) in the olive flounder (P. olivaceus) feeds on growth and feed availability. Seven experimental feeds were formulated. The control (CMC0) diet included 65% FM. In the CMC0 diet, the various (10%, 20%, 40%, 60%, 80%, and 100%) levels of FM were replaced with CMC, named as the CMC10, CMC20, CMC40, CMC60, CMC80, and CMC100 diets, respectively. The total number of 525 juvenile fish (9.2 ± 0.01 g; mean ± SD) was placed into 21 50-L flow-through tanks (25 juveniles/tank) with three replicates. Fish were hand-fed to apparent satiation for 8 weeks. After the 8-week feeding experiment, olive flounder fed the CMC10 (40.0 ± 0.60 g/fish, 2.99 ± 0.021%/day, and 39.57 ± 0.542 g/fish; mean ± SD), CMC20 (47.3 ± 2.58 g/fish, 3.24 ± 0.082%/day, and 45.16 ± 0.760 g/fish), and CMC40 (40.2 ± 1.17 g/fish, 3.00 ± 0.040%/day, and 39.43 ± 0.930 g/fish) diets attained superior (p < 0.0001 for all) weight gain, specific growth rate (SGR), and feed consumption compared to olive flounder fed the CMC0 (35.1 ± 0.96 g/fish, 2.81 ± 0.039%/day, and 33.75 ± 0.544 g/fish), CMC60 (31.7 ± 1.62 g/fish, 2.66 ± 0.068%/day, and 31.60 ± 1.080 g/fish), CMC80 (24.7 ± 0.63 g/fish, 2.33 ± 0.033%/day, and 25.27 ± 0.689 g/fish), and CMC100 (17.8 ± 0.32 g/fish, 1.92 ± 0.021%/day, and 18.99 ± 0.592 g/fish, respectively) diets. Weight gain, SGR, and feed consumption of olive flounder fed the CMC60 diet were comparable to olive flounder fed the CMC0 diet. Feed efficiency and protein efficiency ratio of olive flounder fed the CMC60 diet (1.02 ± 0.007 and 1.79 ± 0.034) were comparable to fish fed the CMC0 diet (1.04 ± 0.012 and 1.85 ± 0.021, respectively). None of the plasma and serum measurements, proximate composition, amino acid profiles, or survival of olive flounder after S. iniae infection were influenced by dietary treatments. In conclusion, CMC can substitute FM up to 60% (39% FM protein in the diet) without deteriorating growth performance, feed availability, or the survival of fish after S. iniae infection.

Dietary Replacement Effect of Fish Meal by Tuna By-Product Meal on Growth and Feed Availability of Red Sea Bream (Pagrus major)

The effect of substituting fish meal (FM) by tuna by-product meal (TBM) on growth and feed availability of red sea bream (Pagrus major) was investigated. Six experimental diets were crested to be isonitrogenous (51.5%) and isolipidic (14.5%). The control (Con) diet contained 55% FM. FM substitution in the Con diet was made in increments of 20 percentage points (20, 40, 60, 80, and 100%), named as the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. Juvenile red sea bream were stocked into 18, 300 L flow-through tanks (50 fish/tank). Red sea bream were hand-fed with each diet until satiation for 8 weeks. No statistical differences in weight gain, specific growth rate (SGR), and feed consumption were found among red sea bream fed the Con, TBM20, and TBM40 diets. Furthermore, feed utilization of fish fed the TBM20, TBM40, TBM60, and TBM80 diets was comparable to red sea bream fed the Con diet. The biological indices, biochemical composition, and hematological parameters of fish were not statistically altered by dietary FM replacement with TBM. The greatest economic profit index was achieved in the TBM40 diet. In conclusion, the replacement of 40% FM with TBM in red sea bream diet appears to be the most recommendable approach without producing retarded growth and feed availability, but maximizing EPI to farmers.

Single and combined effects of CuSO4 and polyethylene microplastics on biochemical endpoints and physiological impacts on the narrow-clawed crayfish Pontastacusleptodactylus

This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L-1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L-1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L-1 MPs and 0.5 mg L-1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs.

Substitution Impact of Tuna By-Product Meal for Fish Meal in the Diets of Rockfish (Sebastes schlegeli) on Growth and Feed Availability

This experiment was performed to assess the substitution impact of fish meal (FM) with tuna by-product meal (TBM) in feeds on growth and feed availability of the early stage of juvenile rockfish (S. schlegeli). Six experimental feeds were prepared to be isonitrogenous and isolipidic. Fifty-five percent of FM was contained in the control (Con) diet. In the Con diet, 20, 40, 60, 80, and 100% FM were replaced by TBM, named the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. A total of 540 early-stage juvenile rockfish averaging 2.4 g was divided into 18 tanks and hand-fed to satiation for 56 days. Weight gain and feed consumption of rockfish fed the TBM20 and TBM40 diets were comparable to rockfish fed the Con diet. The specific growth rate (SGR) of rockfish fed the Con diet was comparable to rockfish fed the TBM20, TBM40, and TBM60 diets. Feed efficiency, biometric indices, hematological parameters, proximate composition, and amino acid profiles of rockfish were not impacted by dietary treatments. The economic profit index (EPI) of the Con, TBM20, and TBM40 diets were higher than that of all other diets. FM up to 40% could be substitutable with TBM in the diets of rockfish without deteriorating weight gain and feed consumption, but producing the highest EPI.

Replacement Effect of Fish Meal by Plant Protein Sources in Olive Flounder (Paralichthys olivaceus) Feeds with an Addition of Jack Mackerel Meal on Growth, Feed Availability, and Biochemical Composition

Application of feed stimulants is very helpful to increase the feed intake of fish, especially in the development of low fish meal (FM) diets. FM replacement effect by various plant protein sources (corn gluten meal (CGM), soy protein concentrate (SPC), and corn protein concentrate (CPC)) in diets with an addition of jack mackerel meal (JMM) as feed stimulants on growth, feed availability, and biochemical composition of olive flounder was elucidated. An experimental design of two-way (two replacement levels (25% and 50%) × 3 replacement sources (CGM, SPC, and CPC)) analysis of variance was adopted. Seven diets were formulated. Amount of 60% FM was contained in the control (Con) diet. In the Con diet, 25% and 50% FM were replaced by CGM, SPC, and CPC with an addition of 12% JMM as feed stimulants, referred to as the CGM25, CGM50, SPC25, SPC50, CPC25, and CPC50 diets, respectively. Four hundred and twenty juvenile fish were distributed into 21 flow-through tanks. All diets were assigned to triplicate groups of fish. Fish were hand-fed to satiation twice a day for 56 days. Both dietary replacement levels and sources had statistical effect on weight gain (P < 0.0001 and P < 0.045, respectively), specific growth rate (SGR) (P < 0.0001 and P < 0.033), and feed consumption (P < 0.0001 and P < 0.03) of fish. Dietary increased FM replacement levels lowered weight gain, SGR, and feed consumption of fish. Weight gain, SGR, and feed consumption of fish fed the Con and CGM25 diets were statistically (P < 0.05) greater than those of fish fed the CGM50, SPC50, and CPC50 diets. Both replacement level and source had no statistical effect on feed utilization, biochemical composition except for statistical effect of replacement source on glycine content of fish, and lysozyme and superoxide dismutase (SOD) activities of fish. FM up to 25% could be substituted with CGM, SPC, and CPC in the olive flounder feeds supplemented with 12% JMM as feed stimulants without compromising growth, feed utilization, and lysozyme and SOD activities.

Effect of chrysophanic acid on immune response and immune genes transcriptomic profile in Catla catla against Aeromonas hydrophila

The effect of chrysophanic acid (CA) (2, 4, and 8 mg kg-1) on the immunity and immune-related gene profile of Catla catla against Aeromonas hydrophila is reported. In both control and treated groups fed with 2 mg kg-1 (2 CA), the phagocytosis, hemolytic, myeloperoxidase content, and superoxide anion production decreased significantly between 6th and 8th weeks, whereas when fed with 4 mg kg-1 CA (4 CA) the H2O2 production and nitric oxide synthase increased significantly between 4th and 8th week. When fed with 2 CA and 4 CA diets, the total protein, bactericidal, and antibody titer increased significantly from the 4th week onwards. When fed with 2 CA, the IL-1β and IL-10 mRNA expression of head kidney leucocytes were significant between weeks 6 and 8. The expressions of toll-like receptors significantly increased when fed with a 4 CA diet from 4th week onwards. The 4 CA group significantly increased in TNF-α, TNF receptor-associated factor 6 (NOD), which influences protein expression, after the 4th week. The mRNA transcription of MHCI, lysozyme-chicken and goose type expressions significantly increased in 4 CA group within the 4th week. In summary, the dietary administration of 4 mg kg-1 of CA (4 CA) provides better immunity and enhances the up-regulation of immune-related genes in Catla against A. hydrophila.

Combined effects of exposure to sub-lethal concentration of the insecticide chlorpyrifos and the herbicide glyphosate on the biochemical changes in the freshwater crayfish Pontastacus leptodactylus

Glyphosate is an herbicide that inhibits the growth of weed plants, while chlorpyrifos is an insecticide commonly applied to control the pests' population. This study aimed to investigate the combined effects of chlorpyrifos and glyphosate on biochemical, immunological parameters, and oxidative stress biomarkers in freshwater crayfish Pontastacus leptodactylus for 21 days. The experimental design of this study was factorial (3 × 3), including 0.0, 0.4, and 0.8 mg L-1 glyphosate and 0.0, 2.5, and 5 µg L-1 chlorpyrifos. The exposure to chlorpyrifos, glyphosate alone and a mixture of them significantly decreased acetylcholinesterase, alkaline phosphatase, phenoloxidase activities, and total protein levels. The lactate dehydrogenase, glutamic-pyruvic-transaminase, and catalase activities, the contents of glucose, and malondialdehyde levels were increased in the crayfish. No significant changes were detected in glutamic-oxaloacetic-transaminase (SGOT) activity, triglyceride, and total antioxidant (TAO) levels in the crayfish treated with 0.4 mg L-1 glyphosate and the control group. Co-exposure of crayfish to chlorpyrifos and glyphosate increased SGOT activity and TAO levels. Although chlorpyrifos combined with glyphosate decreased the γ-Glutamyltransferase (GGT) activity, the GGT activity was significantly increased in the P. leptodactylus exposed during 21 days to 5 µg L-1 chlorpyrifos alone and 0.8 mg L-1 glyphosate alone. In comparison with the reference group, no significant changes were evidenced in the cholesterol levels in the P. leptodactylus treated with 2.5 µg L-1 chlorpyrifos, but its levels were significantly increased in the other treatment groups. In conclusion, the mix of glyphosate and chlorpyrifos exhibited synergic effects on the different toxicological biomarkers in the narrow-clawed crayfish. Co-exposure to pesticides may result in disruption of homeostasis in the crayfish by altering the biochemical and immunological parameters.

Possible Mechanisms of Action of Two Pseudomonas fluorescens Isolates as Probiotics on Saprolegniosis Control in Rainbow Trout (Oncorhynchus mykiss Walbaum)

Probiotics have been proposed as one of the alternatives to the chemical treatments currently used in aquaculture. Recently, the possible usefulness of certain microorganisms, mainly bacteria, has been highlighted as a potential biocontrol for saprolegniosis. In the present work we investigated the possible mechanisms of action of two isolates of Pseudomonas fluorescens (LE89 and LE141) with proven ability to reduce Saprolegnia parasitica infection in rainbow trout under experimental conditions when they are added to the tank water. The stimulation of the innate immune response and the production of siderophores and bioactive substances inhibiting S. parasitica present in cells and supernatants of LE89 and LE141 were studied. Regarding the immune response the only noteworthy points were the increase in the phagocytic activity of macrophages and the concentration of serum proteins when LE141 was administered. Both bacteria produced siderophores. When analyzing the protein substances present in supernatants, it was observed that in both isolates the proteins with inhibitory activity present might be siderophores. In LE141, besides siderophores, a protein of 66 kDa was identified in the fraction responsible for inhibition. To sum up, the two P. fluorescens isolates might be usable for biocontrol of saprolegniosis and that the mode of action of these bacteria is likely to be related to the production of siderophores.

Immunostimulatory and antioxidant effects of supplemental feeding with macroalga Sargassum spp. on goat kids

Algae are a rich source of bioactive compounds and health properties that have been narrowly explored in goat production systems. The aim of this study was to determine the effect of feeding diets supplemented with Sargassum spp. on antioxidant status and immune parameters in goat kids. The diets were as follows: control (basal diet without alga), Sargassum spp. 2.5% (Ss2.5), and Sargassum spp. 5% (S5) fed over a 70-day period. A total of 11 body tissues, intestinal mucus, and blood serum were sampled at necropsy. Protein content, superoxide dismutase (SOD), catalase (CAT), myeloperoxidase (MPO), lysozyme, and anti-protease activities were determined, as well as immunoglobulin A (IgA) and immunoglobulin G (IgG). The results indicated that Sargassum spp. supplementation increased protein content in six tissues. Antioxidant activities (SOD and CAT) and immune-related (lysozyme, MPO, and anti-protease) activities were statistically higher (P < 0.05) in Sargassum spp. groups compared with control in several tissues, intestinal mucus, and serum. Imunoglobulin A levels in intestinal mucus were higher (P < 0.05) in Sargassum spp.-supplemented groups than the control group. In conclusion, diet supplementation of Sargassum spp. improves the antioxidant status and enhances the immune parameters in goats. Sargassum spp. dietary supplementation is proposed as strategy to strengthen antioxidant status and stimulate the immune system, which helps in the control of opportunistic pathogens in goats.

Deiminated proteins and extracellular vesicles - Novel serum biomarkers in whales and orca

Peptidylarginine deiminases (PADs) are a family of phylogenetically conserved calcium-dependent enzymes which cause post-translational protein deimination. This can result in neoepitope generation, affect gene regulation and allow for protein moonlighting via functional and structural changes in target proteins. Extracellular vesicles (EVs) carry cargo proteins and genetic material and are released from cells as part of cellular communication. EVs are found in most body fluids where they can be useful biomarkers for assessment of health status. Here, serum-derived EVs were profiled, and post-translationally deiminated proteins and EV-related microRNAs are described in 5 ceataceans: minke whale, fin whale, humpback whale, Cuvier's beaked whale and orca. EV-serum profiles were assessed by transmission electron microscopy and nanoparticle tracking analysis. EV profiles varied between the 5 species and were identified to contain deiminated proteins and selected key inflammatory and metabolic microRNAs. A range of proteins, critical for immune responses and metabolism were identified to be deiminated in cetacean sera, with some shared KEGG pathways of deiminated proteins relating to immunity and physiology, while some KEGG pathways were species-specific. This is the first study to characterise and profile EVs and to report deiminated proteins and putative effects of protein-protein interaction networks via such post-translationald deimination in cetaceans, revealing key immune and metabolic factors to undergo this post-translational modification. Deiminated proteins and EVs profiles may possibly be developed as new biomarkers for assessing health status of sea mammals.

Evaluation of single and combined effects of cadmium and micro-plastic particles on biochemical and immunological parameters of common carp (Cyprinus carpio)

The growing accumulation of microplastics (MPs) in aquatic environments is a global concern. MPs are capable to interact with other environmental contaminants, including heavy metals, altering their toxicity. The aim of the study was to investigate the sub-lethal effects of cadmium chloride (Cd) alone and in combination with MPs on common carp (Cyprinus carpio). Multi-biomarkers, including plasma biochemical parameters and intrinsic immunological factors, were measured after 30 days of exposure. Exposure to Cd or NPs reduced the plasma activities of acetylcholinesterase (AChE) and gamma-glutamyl-transferase (GGT) and increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). Exposure to both compounds enhanced the observed effects except for AST activity and ALP at the highest concentrations, whereas evidenced an antagonistic interaction in ALT. Plasma total protein, albumin, and globulin levels were decreased, and the levels of glucose, triglyceride, and cholesterol levels increased mainly in the Cd groups with no additional effects derived from the co-exposure to both stressors. Lysozyme and alternative complement (ACH50) activities and the levels of total immunoglobulins, and complement C3 and C4 in fish exposed to Cd and MPs were lower than those in the control group and this decrease was more significant by the mixture of both compounds. These findings showed that the exposure to Cd or MPs alone is toxic to fish altering the biochemical and immunological parameters. Moreover, these alterations are even greater when the Cd and the MPS are combined suggesting synergistic effects in increasing Cd toxicity and vice versa.

Plant extract-based diets differently modulate immune responses and resistance to bacterial infection in striped catfish (Pangasianodon hypophthalmus)

A feeding trial was performed to compare the effects of five ethanol herbal extracts (bhumi amla, Phyllanthus amarus Schum and Thonn [Pa]; guava, Psidium guajava L. [Pg]; sensitive plant, Mimosa pudica L. [Mp]; neem, Azadirachta indica A. Juss [Ai] and asthma plant, Euphorbia hirta L. [Eh]) on the immune response and disease resistance against Edwardsiella ictaluri infection of striped catfish (Pangasianodon hypophthalmus). Fish were fed diets supplemented with two doses of each plant extract (0% [basal diet], 0.4% Eh [Eh0.4], 2.0% Eh [Eh2.0], 0.2% Pa [Pa0.2], 1.0% Pa [Pa1.0], 0.2% Pg [Pg0.2], 1.0% Pg [Pg1.0], 0.4% Mp [Mp0.4], 2.0% Mp [Mp2.0], 0.4% Ai [Ai0.4], 2.0% Ai [Ai2.0]) for 8 weeks. Results showed that hematological parameters (total red blood cells, white blood cells, lymphocytes, monocytes, and neutrophils) of fish fed extract-based diets were significantly higher than in those fed the control diet (p < 0.05) after 4 and 8 weeks. Plasma lysozyme activity increased in fish whose diets contained both doses of Eh (p < 0.05) in week 4 (W4), whereas lysozyme activity increased in fish fed 0.2% Pa and Pg, and 2.0% Ai and Eh (p < 0.05) in week 8 (W8). The lysozyme levels in skin mucus did not significantly differ between treatments (p > 0.05) in W4 and after the bacterial challenge test. At the end of the feeding trial, levels of ACH50 significantly increased in most of extract groups compared to the control group (p < 0.05). Total immunoglobulin increased considerably in both the plasma and skin mucus of fish fed extract-supplemented diets after 8 weeks. In addition, dietary supplementation with Pg, Mp, Pa0.2, Eh2.0, and Ai0.4 for 8 weeks considerably reduced the cumulative mortality against E. ictaluri infection in striped catfish. The results suggest that plant extracts possibly modulate the striped catfish immune response in a time and dose dependent manner. Specifically, diets enriched with extracts of P. guajava at 0.2 and 1.0%, or M. pudica at 2.0% for 8 weeks, have great potential for improving striped catfish health by enhancing the immune system and reducing mortality against bacterial challenges.

Antibacterial synergy between rutin and florfenicol enhances therapeutic spectrum against drug resistant Aeromonas hydrophila

Emergence of antibiotic resistant bacteria has necessitated the drive to explore competent antimicrobial agents or to develop novel formulations to treat infections including Aeromonas hydrophila. The present study investigates the synergistic antibacterial effects of citrus flavonoid rutin and florfenicol (FF) against A. hydrophila in vitro and in vivo. Rutin is extracted and purified from Citrus sinensis peel through preparative HPLC and characterized through TLC, GC-MS and ¹H and ¹³C NMR analyses. Though rutin did not display significant antibacterial activity, it modulated FF activity resulting in four-fold reduction in the MIC value for FF. The anti-biofilm potential of synergistic association of rutin and FF was validated by protein analysis, quantification of exopolysaccharide (EPS) and microscopy studies using sub-MIC doses. Besides antibacterial action, in vivo studies showed that Rutin/FF combination enhanced host immunity by improving blood cell count, anti-protease, and lysozyme activities as well as decreased the oxidative stress and the pathological changes of tilapia Oreochromis niloticus against A. hydrophila infection. No significant DNA damages or clastogenic effects were detected in tilapia challenged with A. hydrophila under Rutin/FF treatment. It is shown that an acute-phase Lipopolysaccharide binding protein (LBP) enhances the innate host defence against bacterial challenge. Semi quantitative RT-PCR and western blot results revealed the significant increase of LBP in the supernatant of tilapia monocytes/macrophages challenged with A. hydrophila upon treatment. The study findings substantiate that the combination of natural molecules with antibiotics may open up possibilities to treat MDR strains.

A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus hippoglossus L.)

A novel 27 kDa ladder-lectin-like protein, showing a multimeric structure under non-reducing conditions, was isolated from halibut serum by binding to N-acetyl glucosamine. Mass-spectrometry analysis did not show significant homology with known proteins. Specific antibodies were produced and used in immunohistochemistry on tissue sections of early halibut ontogeny from 119 until 1050 °d post hatching. A strong positive response was detected in the mucosal cells of the skin, gills and gut, indicating a role in the mucosal immune defence at these sites. Further immunopositivity was detected in liver, myeloma of kidney and the brain at different developmental stages but predominant expression was found in mucosal surfaces at later stages of development tested (1050 °d). It is still uncertain whether this ladder-like lectin forms part of the complement pathway, as a lectin or ficolin, or if it belongs to galectins. A strong detection in mucosal surfaces on skin, gills and gut, show similar patterns of expression as both mucosal lectins and galectins in other fish. Detection in neuronal tissue may indicate putative roles in tissue remodelling of brain and in ongoing neurogenesis in the fish eye.

Possible effect of hala extract (Pandanus tectorius) on immune status, anti-tumour and resistance to Yersinia ruckeri infection in rainbow trout (Oncorhynchus mykiss)

The possible effect of dietary administration of hala extract (Pandanus tectorius) on rainbow trout (Oncorhynchus mykiss) immune status as well as its effect as an anti-tumour agent was studied. Fish were divided into 4 groups before feeding with commercial diet (0%, control; 0.5%, 1% and 2% of hala extract) for 2 weeks. The effect of diet on the humoral immune parameters, ie total protein, myeloperoxidase content, antiproteases, lysozyme and bactericidal activities were studied. Also, the effect of the diets on the expression of some immune-related genes in rainbow trout head-kidney (TNF, LYZ2, IL-8 and CD-4) as well as tumour suppressor gene (WT-1a) was investigated. At the end of the feeding trial fish groups were challenged with Yersinia ruckeri. The results demonstrated enhancement in all the immune parameters in fish fed hala extract diets compared to control fish especially with the highest dose (2%) which recorded the highest significant increase (p < 0.05) in some parameters (total protein, myeloperoxidase content, antiproteases, and bactericidal activities) compared to the control. The results obtained from challenge with Y. ruckeri revealed reduction in the mortalities in fish groups fed with 1% and 2% doses of hala extract. Feeding with hala extract provoked upregulation in all immune- related genes. Again, the highest dose of hala extract showed a significant upregulation in WT1a expression (p < 0.05). The current study suggest that the hala extract, especially the highest dose, could be considered a good food additive to improve the immune status, resist tumour formation and to resist or control infectious diseases of rainbow trout.

Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny - Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.)

Post-translational protein deimination is mediated by peptidylarginine deiminases (PADs), which are calcium dependent enzymes conserved throughout phylogeny with physiological and pathophysiological roles. Protein deimination occurs via the conversion of protein arginine into citrulline, leading to structural and functional changes in target proteins. In a continuous series of early halibut development from 37 to 1050° d, PAD, total deiminated proteins and deiminated histone H3 showed variation in temporal and spatial detection in various organs including yolksac, muscle, skin, liver, brain, eye, spinal cord, chondrocytes, heart, intestines, kidney and pancreas throughout early ontogeny. For the first time in any species, deimination of complement components C3 and C4 is shown in halibut serum, indicating a novel mechanism of complement regulation in immune responses and homeostasis. Proteomic analysis of deiminated target proteins in halibut serum further identified complement components C5, C7, C8 C9 and C1 inhibitor, as well as various other immunogenic, metabolic, cytoskeletal and nuclear proteins. Post-translational deimination may facilitate protein moonlighting, an evolutionary conserved phenomenon, allowing one polypeptide chain to carry out various functions to meet functional requirements for diverse roles in immune defences and tissue remodelling.

Class B CpG-ODN2006 is highly associated with IgM and antimicrobial peptide gene expression through TLR9 pathway in yellowtail Seriola lalandi

The purpose of this study was to characterize the TLR9 gene from yellowtail (Seriola lalandi) and evaluate its functional activity using the class B Cytosine-phosphate-guanine-oligodeoxynucleotide2006 (CpG-ODN2006) in an in vivo experiment after one-week immunostimulation. The gene expressions of TLR9, Immunoglobulin M (IgM), antimicrobial peptides and cytokines were evaluated by real time PCR, and humoral immune parameters were analyzed in serum. The TLR9 nucleotide sequence from yellowtail was obtained using the whole-genome shotgun sequencing method and bioinformatics tools. The yellowtail full-length cDNA sequence of SlTLR9 was 3789 bp in length, including a 66-bp 5'-untranslated region (UTR), a 3'-UTR of 528 bp, and an open reading frame (ORF) of 3192 bp translatable to 1064 amino acid showing a high degree of similarity with the counterparts of other fish species and sharing common structural architecture of the TLR family, including LRR domains, one C-terminal LRR region, and a TIR domain. Gene expression studies revealed the constitutive expression of TLR9 mRNA in all analyzed tissues; the highest levels were observed in intestine, liver and spleen where they play an important role in the fish immune system. The expression levels of TLR9 after B class CpG-ODN2006 (the main TLR9-agonist) was significantly up-regulated in all analyzed tissues, with the high expression observed in spleen followed by intestine and skin. The CpG-B has been shown as a potent B cell mitogen, and interestingly, IgM mRNA transcript was up-regulated in spleen and intestine, which was highly correlated with TLR9 after CpG-ODN2006 stimulation. The antimicrobial peptides, piscidin and NK-lysine, were up-regulated in spleen and gill after CpG-ODN2006 injection with a high correlation (r ≥ 0.82) with TLR9 gene expression. Cytokine genes were up-regulated in spleen, intestine and skin after CpG-ODN was compared with the control group. No significant correlation was observed between TLR9 and IL-1β, TNF-α and Mx gene expressions. The results showed that CpG-ODN2006 intraperitoneal injection enhanced lysozyme, peroxidase and superoxide dismutase activities in serum and demonstrated that CpG-ODN2006 can induce a specific immune response via TLR9 in which IgM and antimicrobial peptides must have an important role in the defense mechanisms against infections in yellowtail.

Modulation of systemic and mucosal immune responses of Catla catla (Hamilton, 1822) experimentally challenged with gill monogeneans

The present study investigated the modulation of systemic and mucosal immunity of catla (Catla catla) experimentally challenged with gill monogeneans. Fingerlings of catla (24.2 ± 1.5 g) without any parasites were randomly distributed into two groups each comprising quadruplicate tanks (10 fish per tank). The fish in the infected group were challenged with gill monogeneans by cohabitation method. The control group fish were not exposed to parasites. Serum and mucus were collected from both control and infected fish and different immunological parameters were measured at weekly interval for four weeks. Monogeneans on the fish gills were also quantified from infected fish at weekly interval. Different systemic immunological parameters viz. myeloperoxidase content, alkaline phosphatase and hemolytic activity of serum showed a significant increase (p < .05) in infected group. However, respiratory burst activity, total serum protein and anti-protease activity did not show any significant enhancement (p < .05) in infected group compared to control. In case of mucosal parameters, myeloperoxidase content, alkaline phosphatase activity, total protein content and anti-protease activity of mucus showed significant enhancement (p < .05) in infected group compared to control. Parasite prevalence was 100% in the infected group in all the sampling weeks. The mean intensity of parasites was progressively increased and the highest number of monogeneans per gill (45 ± 4.56) was observed during 4th week post challenge. Control group had mean intensity and prevalence of zero. In conclusion, there was the participation of immune system components against monogenean infection in catla. However, the progressive increase in monogenean intensity indicates some immune evasion mechanism available with the monogenean to co-exist with the host in the face of host's immune responses.

In vivo and in vitro studies using larval and adult antigens from Neobenedenia melleni on immune response in yellowtail (Seriola lalandi)

Neobenedenia melleni is a monogenean parasite that causes significant mortality and economic losses in fish aquaculture. Changes in the antigenic composition of this parasite occur during its developmental stages. In this study, we evaluated humoral parameters in serum and transcriptional immune responses of yellowtail naturally infected with N. melleni. In addition, in vitro assays were performed to study the stimulatory effects of antigens from larvae and adults on spleen leucocytes from non-infected fish at 6 and 24 h post-stimulation. The results showed enhanced total protein, myeloperoxidase and antiprotease activities in N. melleni-infected fish compared with non-infected ones. The induction of Toll-like receptors (TLRs) and pro-inflammatory cytokines in spleen leucocytes during natural infection with N. melleni suggests that these immune-related genes play an important role in the initiation of the immune defence mechanism for controlling parasite infection. Interestingly, the magnitude of in vitro responses of spleen leucocytes was dependent on the parasitic stage. An important stimulation of gene expression by adult antigens on spleen leucocytes was observed. Differential expression patterns of TLRs and target cytokines in yellowtail leucocytes in both in vivo and in vitro studies suggest that the quality of yellowtail immune response is conditioned by N. melleni development.

Dietary yeast Sterigmatomyces halophilus enhances mucosal immunity of gilthead seabream (Sparus aurata L.)

A yeast was isolated from hypersaline sediments, grown and phylogenetically characterized as Sterigmatomyces halophilus strainN16. The dietary administration of this yeast was studied for its effect on skin mucosal immune and antioxidant status of gilthead seabream (Sparus aurata L.). Fish were fed a commercial diet (control, non-supplemented diet), or the same commercial diet supplemented with 0.55% or 1.1% of yeast for 15 and 30 days. One month after the end of the trial, fish from all treatments were intraperitoneally injected with pathogenic Vibrio parahaemolyticus and further fed with the same diets for one week, after which fish were also sampled. Significant increases were observed in the immune activities determined in the fish fed the yeast supplemented diets compared with the values recorded in mucus of fish from the control group. The expression levels of trypsin (one of the main digestive enzymes) and several immune-related genes (IL-1β, TNF-α, IgM, C3 and lysozyme) were also evaluated by real-time PCR in intestine and skin. Interestingly, trypsin gene expression in intestine was up regulated in both experimental diets compared with the control group, particularly in fish fed with 0.55% of S. halophilus at any time of the experimental trial. Immune-related genes in intestine and skin were strongly expressed principally in fish fed with 0.55% of S. halophilus for 15 days and 1.1% for 30 days and after infection, respectively. The present results suggest that the yeast S. halophilus can be considered as a novel fish immunostimulant. The excellent potential of marine microorganisms isolated from extreme environments with beneficial properties for fish is discussed.

Enhancing gilthead seabream immune status and protection against bacterial challenge by means of antigens derived from Vibrio parahaemolyticus

In an attempt to control the proliferation of the pathogenic bacterium Vibrio parahaemolyticus in gilthead seabream (Sparus aurata), the immunostimulant effect of lysate and ToxA from this bacterium was evaluated. Fish were intraperitoneally injected twice (first injection, day 1 of the experiment; second injection, day 7) and sampled after one week (on days 8 and 15). Afterwards, all fish specimens were experimentally infected with V. parahaemolyticus and mortality was recovered for 1 week. Fish injected with lysate, ToxA and phosphate buffer saline (control) showed 100%, 50% and 0% survival, respectively, when challenged with the pathogen. Skin mucus immune parameters and immune-related gene expression in skin and spleen were also evaluated. The results showed that mucus immune parameters were enhanced in the lysate and ToxA groups compared with the values obtained for fish from the control group. Expression of IL-1β, TNF-α, C3 and IgM genes was significantly up-regulated in the lysate and ToxA groups, principally after infection with the bacterium. Interestingly, TLR5 gene expression increased in fish immunized with lysate. The most prominent histological characteristic in gut from infected fish was the presence of a great number of intraepithelial leucocytes as well as inflammation of the submucosa, while severe hydropic degeneration and hemosiderosis were detected in liver from infected fish. Injection of lysate or ToxA had a protective effect against the deleterious consequences of subsequent infection with V. parahaemolyticus in gut and liver. The findings underline the potential of lysate and ToxA as potent preventive antigens against this kind of vibriosis.

Changes in the levels of humoral immune activities after storage of gilthead seabream (Sparus aurata) skin mucus

Skin mucus is increasingly used as a source for determining immunity-related proteins and enzymes. However, the ability to accurately measure some activities may be modified by inadequate handling and storage of the samples. This study aims to measure the effect of freezing and lyophilization at the time of collection on such activities. Fresh, frozen (immediately after collection at -20 °C and -80 °C) and lyophilized skin mucus samples obtained from the same groups of fish specimens of gilthead seabream (Sparus aurata L.) were analysed in the assays. The amount of total proteins and sugar residues (determined by lectin binding) present in skin mucus samples fell after both freezing and lyophilization of the samples. While no significant differences were exhibited in the levels of some proteins or enzymes (immunoglobulin M, antiprotease, peroxidase, esterase and alkaline phosphatase) determined in fresh or frozen mucus samples, protease and lysozyme activities were lower in frozen mucus samples than in fresh samples. Lyophilization of the mucus samples drastically decreased the total level of proteins obtained, as well as of protease, peroxidase, lysozyme and alkaline phosphatase activities. The results suggest that freezing skin mucus samples is more suitable than lyophilization if samples are stored before determining enzymatic activities.

Humoral immune response and TLR9 gene expression in Pacific red snapper (Lutjanus peru) experimentally exposed to Aeromonas veronii

Aquaculture production of Pacific red snapper Lutjanus peru is growing rapidly in Mexico, especially in Gulf of California. As it is a relatively new aquaculture species there are few reports evaluating its immune response to pathogens. The Gram-negative bacteria Aeromonas veronii is a heterogeneous organism that causes the disease known as motile aeromonad septicemia, which is responsible for serious economic loss in seabream culture due to bacterial infections. For the purpose of this study, juvenile Pacific red snapper specimens were intraperitoneally injected with low doses of A. veronii (1 × 10(6) CFU ml(-1)). Changes in humoral immune parameters (total protein, myeloperoxidase, lisozyme and antiprotease activities and IgM levels), as well as superoxide dismutase and catalase activities, and TLR9 gene expression were evaluated 24 and 48 h after injection. Overall, the results showed an enhanced in humoral immune parameters and SOD and CAT activities in fish infected with A. veronii compared with control group at 24 or 48 h. By real time PCR assays, the basal mRNA transcripts of TLR9 showed that were highly expressed in intestine and leucocytes compared to skin, head kidney, liver and gill. Then, the mRNA expression levels of TLR9 in head kidney, skin, liver and intestine were analyzed in non-infected and experimentally infected fish 24 and 48 h after injection. A. veronii up-regulated the expression of TLR9 at 24 or 48 h of exposure in all samples analyzed except in liver. Interestingly, intestine produced the greatest increase in transcript levels upon exposure (48 h) to A. veronii. Taken together, our results suggest that low doses of A. veronii infection inducing humoral immune system and TLR9 immune gene in Pacific red snapper that can be useful in the health control of this species.

Dietary administration of microalgae alone or supplemented with Lactobacillus sakei affects immune response and intestinal morphology of Pacific red snapper (Lutjanus peru)

The aim of this study was to evaluate the effect of dietary microalgae Navicula sp single or in combination with Lactobacillus sakei on growth performance, humoral immune parameters and intestinal morphology in Pacific red snapper, Lutjanus peru. The experimental fish were grouped into four treatment diets which were a control diet (commercial diet, Control), silage microalgae Navicula sp plus L. sakei (10(6) CFU g(-1), Navicula + L. sakei), lyophilized microalgae (Navicula) and L. sakei (10(6) CFU g(-1), L. sakei). The blood and intestine samples were collected on week 4 and 8. The weight gain showed an additive effect of Navicula + L. sakei at 8 weeks of treatment compared with fish fed control diet. Overall, physiological parameters such as total protein and hemoglobin were increased in fish fed with Navicula and L. sakei diets at 4 and 8 weeks of feeding assay, respectively. There was a significant improvement in immune parameters, principally in myeloperoxidase, lysozyme, total antiproteases activities and IgM in fish fed with Navicula + L. sakei and L. sakei diets at 4 or 8 weeks of treatments. Serum antioxidant capabilities revealed significant increase in phosphatase alkaline, esterase, protease, superoxide dismutase and catalase in groups which received diet supplemented with Navicula + L. sakei and L. sakei diets. Finally, light microscopy observations revealed no effect of experimental diets on microvilli height. Curiously, the presence of vacuoles inside the enterocytes was significant higher in the intestine of L. sakei group after four or six weeks of feeding. Elevated intraepithelial leucocyte levels and melanomacrophages centers were observed in fish fed Navicula or control diets at any time of the experiment. To conclude, the results of the present study demonstrate that the fish that were fed with Navicula + L. sakei or L. sakei diets yielded significantly better immune status and antioxidant capabilities.

Single or combined effects of Lactobacillus sakei and inulin on growth, non-specific immunity and IgM expression in leopard grouper (Mycteroperca rosacea)

The aim of this study was to evaluate the single or combined effects of Lactobacillus sakei with inulin suitable for immunological in vivo studies in farmed fish. By in vitro assays, L. sakei strain 5-4 showed antibacterial activities against all assayed fish pathogens (except the Vibrio harveyi strain CAIM-1793). L. sakei was able to survive at high fish bile concentrations. Fermentation of the agave inulin resulted in a large increase in number of lactobacilli. For the in vivo study, fish were fed for 8 weeks four practical diets: control diet (control), L. sakei 5-4 (10(7) CFU/g), inulin (1% or 10 g/kg) and L. sakei + inulin (10(7) CFU/g + 10 g/kg). The weight gain showed clearly the synergistic effect of L. sakei 5-4 and inulin at 6 and 8 weeks of treatments. Leopard grouper fed with L. sakei alone or combined with inulin have significantly increased the assayed physiological and humoral immune parameters. By real-time PCR assays, the mRNA transcripts of immunoglobulin M (IgM) were found to be higher expressed in intestine, head kidney, mucus, gill, spleen and skin. Moreover, mRNA expression levels of IgM in head kidney and anterior intestine were measured by real-time PCR. L. sakei 5-4 and L. sakei + inulin supplemented diet up-regulated the expression of IgM at week 4 and 8 in intestine and head kidney, respectively. These results support the idea that the L. sakei 5-4 alone or combined with agave inulin improved growth performance and stimulates the immune system of leopard grouper.

The effect of aflatoxin-B1 on red drum (Sciaenops ocellatus) and assessment of dietary supplementation of NovaSil for the prevention of aflatoxicosis

Aflatoxin B1 (AFB1) is a potent carcinogen that causes growth stunting, immunosuppression and liver cancer in multiple species. The recent trend of replacing fishmeal with plant-based proteins in fish feed has amplified the AFB1 exposure risk in farm-raised fish. NovaSil (NS), a calcium montmorillonite clay, has previously been shown to reduce AFB1 bioavailability safely and efficaciously in several mammalian species. This study was designed to: (1) evaluate AFB1 impact on cultured red drum, Sciaenops ocellatus, over the course of seven weeks; and (2) assess NS supplementation as a strategy to prevent aflatoxicosis. Fish were fed diets containing 0, 0.1, 0.25, 0.5, 1, 2, 3, or 5 ppm AFB1. Two additional treatment groups were fed either 5 ppm AFB1 + 1% NS or 5 ppm AFB1 + 2% NS. Aflatoxin B1 negatively impacted red drum weight gain, survival, feed efficiency, serum lysozyme concentration, hepatosomatic index (HSI), whole-body lipid levels, liver histopathological scoring, as well as trypsin inhibition. NovaSil inclusion in AFB1-contaminated diets improved weight gain, feed efficiency, serum lysozyme concentration, muscle somatic index, and intraperitoneal fat ratios compared to AFB1-treated fish. Although not significant, NS reduced AFB1-induced histopathological changes in the liver and decreased Proliferating Cell Nuclear Antigen (PCNA) staining. Importantly, NS supplementation improved overall health of AFB1-exposed red drum.

Streptococcous parauberis infection in starry flounder, Platichthys stellatus: characterization of innate immune responses following experimental infection

Streptococcus parauberis causing systemic infections has been recognized as a major bacterial disease in olive flounder Paralichthys olivaceus in South Korea. Although an emerging outbreak of S. parauberis has affected heavily farmed fish species starry flounder Platichthys stellatus, no study of the innate immune responses and pathogenic mechanisms in starry flounder is available. In the present study, starry flounder were intraperitoneally challenged with four S. parauberis strains to investigate changes in innate immune responses. Significant increases in serum lysozyme activities, superoxide production of kidney leucocytes, and serum superoxide dismutase activities were observed following experimental injection of S. parauberis. All these data suggested that the innate immune parameters were highly modulated during the S. parauberis infection process to render protection to the starry flounder. However, S. parauberis also exhibited the mechanisms to complete disease establishment by avoiding host immune responses. S. parauberis could survive and proliferate in the mucus, serum and kidney leucocytes of starry flounder. In particular, the strain isolated from the starry flounder showed the higher survival ability than other originated strains in the tested host fish.

Effects of marine silages enriched with Lactobacillus sakei 5-4 on haemato-immunological and growth response in Pacific red snapper (Lutjanus peru) exposed to Aeromonas veronii

Combined effects of marine silages enriched with Lactobacillus sakei 5-4 were evaluated on growth performance, immune activity and disease resistance of Pacific red snapper (Lutjanus peru) against Aeromonas veronii infection. The experimental fish were divided into three groups which were fed with each one of the following diets: silage-probiotic-free diet (control, C group), Pacific creole-fish silage diet supplemented with live L. sakei (10(6) CFU g(-1)) (FSLact group) and Humboldt squid silage diet supplemented with live L. sakei (10(6) CFU g(-1)) (SSLact group) for 6 weeks. After 6 weeks, fish were immunocompromised with pathogenic A. veronii and spleen and liver samples were processed for histopathological studies. Generally, the results showed enhanced growth performance in fish fed the diet containing SSLact at 6 and 7 weeks compared with fish fed control diet. Addition of SSLact had an increase in plasmatic protein at week 6 and post-challenge. Hemoglobin concentration increased after challenge in fish fed with SSLact compared to control group. At week 6 and post-challenge the results indicated that, the fish groups which received diet supplemented with SSLact revealed significant increase in humoral immune parameters. Histologically, fish fed C diets showed marked fatty degeneration and great activation of melanomacrophage centers compare with SSLact and FSLact groups. These results support the idea that the marine silages with squid as protein source enriched or combined with L. sakei 5-4 increases the body weight and stimulates the physiological and humoral immune parameters in Pacific red snapper infected with A. veronii.

Biostatic activity of piscine serum and mucus on myxozoan fish infective stages

Since the basis of host specificity in Myxozoa, i.e. the differential disposition and extinction of erroneously penetrated myxozoan infective stages in non-susceptible fish hosts, remains puzzling, we aimed to explore the role of the innate immune system in this issue. In a comparative incubation challenge of actinospore sporoplasms of the freshwater parasite species Myxobolus cerebralis, Henneguya nuesslini and Myxobolus pseudodispar to isolates of host and non-host muci and blood sera, we measured cellular disintegration proportions and times by means of a double staining viability assay utilizing fluorescent dyes. After their activation, emerging primary and secondary sporoplasm cells were evaluated microscopically for physical integrity and onset of cell death due to exposure. Impairment by any mucus used was not detected up to 100 min of exposure. All parasites showed significantly increased cellular breakdown in non-susceptible host serum compared to the respective substrates from susceptible host fish. Except for M. cerebralis, the serum of the susceptible host was considerably less effective over time. In this species, both the primary and the secondary cells were affected in much shorter times than in the other two representatives. Inhibition of protease activity did not affect carp serum effect on M. cerebralis stages. We suggest the active components to be complement or complement induced factors since heat inactivation and withdrawal of bivalent metal ions lowered serum activity significantly. The study marks the first in vitro viability challenge of activated myxozoan transmission stages with teleost derived immune factors.

Kalopanax pictus as feed additive controls bacterial and parasitic infections in kelp grouper, Epinephelus bruneus

Feeding kelp grouper, Epinephelus bruneus (26.1 ± 1.4), with 0%, 0.1%, 1.0%, and 2.0% Kalopanax pictus extract-supplementation diets, for 30 days reduced mortality on being challenged intraperitoneally 100 μl with bacterium Vibrio alginolyticus (2.1 × 10(7) cfu ml(-1)) and ciliate parasite Philasterides dicentrarchi (2.3 × 10(7) ciliates ml(-1)). The red blood cells (RBC), white blood cells (WBC), haemoglobin, haematocrit, lymphocytes, and monocytes levels significantly increased in kelp grouper fed with all doses of K. pictus-supplementation diets and challenged with bacterium and parasite when compared to control. However, the levels of mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), neutrophils, and thrombocytes did not significantly. The phagocytic activity, complement activity, and antiprotease activity did not significantly change in kelp grouper fed with 0.1% K. pictus-supplementation diets and challenged with bacterium and parasite. The respiratory activity, lysozyme activity, bactericidal activity, total protein level, and myeloperoxidase levels significantly increased in kelp grouper fed with all the doses of K. pictus-supplementation diet and challenged with bacterium and parasite. However, α2-macroglobulin level significantly increased with 1.0% diet, but not with 0.1% and 2.0% diets. Therefore this study suggests that 1.0% and 2.0% K. pictus-supplementation diets positively protected and enhanced the immune system in kelp grouper E. bruneus against V. alginolyticus and P. dicentrarchi infection.

Immunological control of fish diseases

All metazoans possess innate immune defence system whereas parameters of the adaptive immune system make their first appearance in the gnathostomata, the jawed vertebrates. Fish are therefore the first animal phyla to possess both an innate and adaptive immune system making them very interesting as regards developmental studies of the immune system. The massive increase in aquaculture in recent decades has also put greater emphasis on studies of the fish immune system and defence against diseases commonly associated with intensive fish rearing. Some of the main components of the innate and adaptive immune system of fish are described. The innate parameters are at the forefront of immune defence in fish and are a crucial factor in disease resistance. The adaptive response of fish is commonly delayed but is essential for lasting immunity and a key factor in successful vaccination. Some of the inherent and external factors that can manipulate the immune system of fish are discussed, the main fish diseases are listed and the pathogenicity and host defence discussed. The main prophylactic measures are covered, including vaccination, probiotics and immunostimulation. A key element in the immunological control of fish diseases is the great variation in disease susceptibility and immune defence of different fish species, a reflection of the extended time the present day teleosts have been separated in evolution. Future research will probably make use of molecular and proteomic tools both to study important elements in immune defence and prophylactic measures and to assist with breeding programmes for disease resistance.

Use of lupin, Lupinus perennis, mango, Mangifera indica, and stinging nettle, Urtica dioica, as feed additives to prevent Aeromonas hydrophila infection in rainbow trout, Oncorhynchus mykiss (Walbaum)

Feeding rainbow trout, Oncorhynchus mykiss (Walbaum), with 1% lupin, Lupinus perennis, mango, Mangifera indica, or stinging nettle, Urtica dioica, for 14 days led to reductions in mortality after challenge with Aeromonas hydrophila. In addition, there was significant enhancement in serum bactericidal activity, respiratory burst and lysozyme activity in the treatment groups compared to the controls. Use of lupin and mango led to the highest number of red blood and white blood cells in recipient fish, with use of stinging nettle leading to the highest haematocrit and haemoglobin values; the highest value of mean corpuscular volume and haemoglobin was in the control groups and those fed with stinging nettle.

Analysis of effects induced by a pollock protein hydrolysate on early development, innate immunity and the bacterial community structure of first feeding of Atlantic halibut (Hippoglossus hippoglossus L.) larvae

A pollock protein hydrolysate was used for enrichment of the live feed offered to halibut larvae from the onset of exogenous feeding and the effects of treatment on selected innate immune parameters studied. The effects of treatment on the bacterial community structure of larvae were furthermore studied using the PCR-DGGE method. C3 and lysozyme were identified in larvae already at the onset of first feeding and low concentrations of IgM detected at this stage indicate maternal origin. Endogenous production of IgM was validated in the gastrointestinal tract of larvae from 29 days post onset of first feeding, with similar concentrations found in both groups. Feeding the peptide-enriched live feed stimulated production of lysozyme and affected the distribution of C3 in larval tissue but survival and normal development of halibut larvae were not affected by the treatment. Vibrio sp. and Pseudoalteromonas sp. dominated the bacterial community of larvae from both groups and peptide enrichment of the live feed was not found to affect the bacterial community structure associated with surface sterilized larvae.

Cell markers and determinants in fish immunology

Despite the impressive increase in the cloning and expression of genes encoding fish immunoregulatory molecules, the knowledge on "in vivo" and "in vitro" functional immunology of the corresponding peptide products is still at an initial stage. This is partly due to the lacking of specific markers for immunoregulatory peptides, that represent an indispensible tool to dissect immune reactions and to trace the fate of cellular events downstream of the activation. In this review we summarise the available information on functional immune activities of some teleost species and discuss the obtained data in an evolutionary and applied context.

Immune responses and enhanced disease resistance in Chinese drum, Miichthys miiuy (Basilewsky), after oral administration of live or dead cells of Clostridium butyrium CB2

Clostridium butyrium CB2 isolated from chickens was tested as a potential fish probiotic in the Chinese drum, Miichthys miiuy. Fish were fed live (CB), dead CB2 (D-CB) cells (10(8) cells g(-1)) or spent culture supernatant (SCS), for 30 days and challenged with Vibrio anguillarum or Aeromonas hydrophila. Survival was higher in both the CB and the CB-D fed groups, but the SCS group was not significantly different from the control. After feeding live or dead CB2 cells, there was increase in phagocytic activity of the head kidney macrophages, the lysozyme activity of serum and gut mucosa and immunoglobulin (Ig) level. The SCS group showed no obvious change in immune parameters. The results suggest that live or dead Clostridium butyrium CB2 has an immunomodulatory effect on fish.

Evaluation of non-specific immune components from the skin mucus of olive flounder (Paralichthys olivaceus)

The innate immune system, particularly the external body surface, plays a frontier role in protecting fish under intensive aquaculture and at prolonged low temperatures from relevant infections due to inadequate adaptive immune responses. In the present study we aimed to understand the mucosal immunity of an economically important mariculture fish, olive flounder (Paralichthys olivaceus) by evaluating the immune components from its skin mucus. The activities of lysozyme (233.33+/-171.82 units mg(-1)), trypsin-like protease (42.84+/-1.249 units mg(-1)), alkaline phosphatase (0.376+/-0.005 units mg(-1)) and esterase (0.170+/-0.006 units mg(-1)) were detected in the skin mucus. Transferrin was identified by MALDI-TOF/MS analysis. ELISA and immunoblot assays using anti-flounder IgM monoclonal antibody showed the presence of a significant level (1.80+/-0.001, n=3) of monomer immunoglobulin M (IgM) with approximate molecular weight of 160 and 25 kDa under non-denaturing and denaturing states, respectively. Skin mucus showed strong antibacterial activity against tested fish pathogenic bacteria. In addition, skin mucus successfully agglutinated (HA titre 2(8)), but completely failed to haemolyse, rabbit erythrocytes. In conclusion, the major immune components of the skin mucus, identified in the present study, are possibly involved in the broad spectrum non-specific immunity of olive flounder.

The innate immune response of finfish--a review of current knowledge

The decline in the fisheries of traditional marine species has been an incentive for the diversification of today's aquaculture sector into the intensive rearing of many finfish species. The increasing interest in commercial farming of different finfish species is expected to result in similar environmental and husbandry-related problems as have been experienced in the development of the salmonid farming industry. An understanding of the biology of the fish species being cultured, in particular the immune response is important for improved husbandry and health management of the species. The innate immune system of fish has generated increasing interest in recent years and is now thought to be of key importance in primary defence and in driving adaptive immunity. This review focuses on key components (cellular and humoral) of the innate immune responses of different fish species of commercial importance.

Innate immune responses in rainbow trout (Oncorhynchus mykiss, Walbaum) induced by probiotics

Carnobacterium maltaromaticum B26 and Carnobacterium divergens B33, which were isolated from the intestine of healthy rainbow trout (Oncorhynchus mykiss, Walbaum), were selected as being potentially useful as probiotics with effectiveness against Aeromonas salmonicida and Yersinia ruckeri. Thus, rainbow trout administered with feed supplemented with B26 or B33 dosed at >10(7) cells g(-1) feed conferred protection against challenge with virulent cultures of the pathogens. Moreover, both cultures persisted in the gut for up to 3 weeks after administration. The cultures enhanced the cellular and humoral immune responses. Specifically, fish fed with B26 demonstrated significantly increased phagocytic activity of the head kidney macrophages, whereas the use of B33 led to significant increases in respiratory burst and serum lysozyme activity. Also, the gut mucosal lysozyme activity for fish fed with both cultures was statistically higher than the controls.

Complement component C3 transcription in Atlantic halibut (Hippoglossus hippoglossus L.) larvae

The complement systems of fish are well developed and play an important role in the innate immune response. Complement C3 is the central protein of all three activation pathways and is the major opsonin of the complement system and essential for the generation of the membrane attack complex. A 1548 bp part of complement component C3 was isolated from a halibut liver cDNA library by immunoscreening. The deduced amino acid sequence showed that this part of halibut C3 contained key amino acids for factor H, I and properdin binding as well as two N-glycosylation sites. Digoxigenine labelled mRNA probes were synthesised and the transcription of C3 was monitored in three larval stages at 206, 430 and 1000 degrees d (30, 50 and 99 days post hatching), by in situ hybridisation. C3 mRNA was detected in muscle, liver, brain, chondrocytes, spinal cord, eye, intestines, oesophagus and kidney. These findings are in accordance with a former immunohistochemical study on halibut C3 protein ontogeny, indicating that C3 is indeed locally expressed in many organs from the youngest stages on. Complement may thus be linked to the formation and generation of different organs during development and play an important role in the early immune response of halibut larvae.

Antibody repertoire development in teleosts--a review with emphasis on salmonids and Gadus morhua L

The group of teleosts is highly diverse, comprising more than 23000 extant species. Studies of the teleost antibody repertoire have been conducted in many different species within different orders, though some species and families have been better characterised than others. The Atlantic cod (Gadus morhua L.) and several species within the Salmoninae (e.g. Salmo salar and Oncorynchus mykiss) are among the best-studied teleosts in terms of the antibody repertoire. The estimated size of the repertoire, the organisation of immunoglobulin (IG) gene segments, the expressed IG repertoire, the IgM serum concentration, and the serum antibody responses reveal some fundamental differences between these species. The serum IgM concentration of G. morhua is some ten times higher than that of S. salar, though G. morhua is characterised as a 'low' (or 'non') responder in terms of specific antibody production. In contrast, an antibody response is readily induced in S. salar, although the response is strongly regulated by antigen induced suppression. The IGHD gene of G. morhua has a unique structure, while the IGHM and IGHD genes of S. salar have a characteristic genomic organisation in two parallel loci. In addition, salmonids, express a broad repertoire of IGH and IGI V-region gene segments, while a single V gene family dominates the expressed heavy and light chain repertoire of G. morhua. Little is known about the developing antibody repertoire during ontogeny, in different stages of B-cell maturation, or in separate B-cell subsets. Information on the establishment of the preimmune repertoire, and the possible role of environmental antigens is also sparse.

Serum immunoglobulin M in Atlantic halibut (Hippoglossus hippoglossus): characterisation of the molecule and its immunoreactivity

Three preparations of purified immunoglobulin (IgM) were isolated from serum of Atlantic halibut (Hippoglossus hippoglossus) by means of three different methods, and each of the three IgM preparations was used to produce a polyclonal rabbit anti-halibut IgM antiserum. One of the IgM preparations was employed in the characterisation of halibut serum immunoglobulin. Halibut IgM was shown to consist of two subunits, compatible with heavy (mu) and light (L) chains. A single mu chain at approximately 76 kDa, and six possible molecular weight (MW) variants of L chain were found (range approximately 25 to approximately 28.5 kDa). IgM was glycosylated on the heavy chain and N-linked carbohydrate constituted approximately 10.3% (w/w) of the total MW of IgM. The dominant form of non-reduced IgM had a MW of approximately 780 kDa, suggesting a tetrameric structure. Non-reduced IgM also showed a number of minor protein bands. Based on estimated MW, the relative carbohydrate content and the reactivity with all three anti-halibut IgM antisera, mono-, di- and trimeric redox forms of IgM were identified. The three antisera were characterised as to specificity and reactivity by means of enzyme linked immuno-sorbent assay (ELISA), crossed immuno-electrophoresis (CIE), and immunoblotting methods. The antisera showed a considerable diversity in their specificity to the suggested MW variants of halibut Ig light chain. A method for immunohistochemical detection of IgM in tissue was established. Protein A or protein G affinity for the IgM was not detectable.

Use of a probiotic to control lactococcosis and streptococcosis in rainbow trout, Oncorhynchus mykiss (Walbaum)

From a comparison of 125 bacterial isolates recovered from the digestive tract of rainbow trout, Oncorhynchus mykiss, and carp, Cyprinus sp., a culture was obtained which was effective at preventing clinical disease caused by Lactococcus garvieae and Streptococcus iniae when used as a feed additive. The culture, Aeromonas sobria GC2, was incorporated into the feed and fed to rainbow trout (average weight = 20 g) for 14 days at a dose equivalent to 5 x 10(7) cells g(-1) of feed. Whereas the untreated controls experienced losses of 75-100% when challenged intraperitoneally with L. garvieae and S. iniae, the probiotic-treated groups remained healthy with total mortalities of only 0-6%. Formalized and sonicated preparations of GC2 and cell-free supernatant fared less well. The mode of action reflected stimulation of innate immunity, namely an increased number of leucocytes and enhanced phagocytic and respiratory burst activity.