Modulatory effects of laurel-leaf cistus (Cistus laurifolius) ethanolic extract on innate immune responses and disease resistance in common carp (Cyprinus carpio).

Medicinal herbs are used for growth promotion, disease control and other health benefits in aquaculture industry. Here, we examined the effect of dietary laurel-leaf cistus (Cistus laurifolius) ethanolic extract on growth performance, digestive enzyme activity, haematological profile and nonspecific immune responses in common carp (Cyprinus carpio). In addition, resistance against Aeromonas hydrophila infection was examined. Common carp was fed diets containing 0 (Control), 0.1 (CL0.1), 0.5 (CL0.5) and 1 (CL1) g kg-1 laurel-leaf cistus extract for 45 days. After 30 days, superoxide anion production (SAP) increased in CL0.1 and CL0.5 fish groups and at the end of the study all experimental fish groups had higher SAP compared to that of the control (P ˂ 0.05). Lysozyme activity (LA) was elevated in CL0.5 and CL1 treated groups on 30th day (P < 0.05), and this increase was only observed in C0.1 fish group at the end of study compared to control (P ˂ 0.05). Myeloperoxidase activity was significantly increased in CL0.5 and CL1 fish groups at the end of study. IL-1ßgene expression was significantly increased in treated fish in a dose-depended manner. Similar results were observed for transcription of IL-6 and IL-8 (P < 0.05). Anti-inflammatory cytokines, IL-10 and TGF-ß were highly up-regulated in the intestine and head kidney of CL treated fish groups compared to control (P < 0.05). At the end of experiment, significantly higher final body weight, weight gain, and specific growth rate were obtained in CL0.1 treated fish group compared to control. However, growth was negatively affected in CL1 fish group (P < 0.05). CL1 fish group had also a significantly higher FCR. Amylase activity was significantly increased in all experimental fish groups compared to control (P ˂ 0.05). Trypsin activity was decreased in CL0.1 and CL1 fish groups (P ˂ 0.05). WBC and RBC were significantly increased (P ˂ 0.05) in CL0.5 and CL1 fish groups, whereas haemoglobin, haematocrit, mean cell, mean cell haemoglobin contents were no significantly changed among control and treatment groups. Result of challenge test with A. hydrophila exhibited that survival rate in all treatment groups was significantly higher than that of control. These findings demonstrated that laurel-leaf cistus at 0.1 g kg-1 can be a suitable candidate for growth promotion, immune system induction and infection control in fish.

Dietary selenium promotes the growth performance through growth hormone-insulin-like growth factor and hypothalamic-pituitary-thyroid axes in grass carp (Ctenopharyngodon idella).

Selenium (Se), an essential component of deiodinases (DIOs), regulates the contents of thyroid hormones and thus improves animal growth. To explore the influences of selenium supplementation on fish growth metabolism, a total of 270 healthy grass carp (Ctenopharyngodon idella) were divided into three groups and feed three graded dietary selenium (0.141, 0.562, and 1.044 mg Se/kg) levels. The results showed that after 60-day feeding, dietary selenium improved the final body weight and specific growth rate (SGR) of grass carp. The hepatic DIO activities in selenium-supplemented groups were higher than those in control group. A significant increase in triiodothyronine (T3), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH) levels was accompanied by a decrease in the contents of thyroxine (T4) and free thyroxine (FT4) in selenium-supplemented groups. The histopathological observation of thyroid suggested that selenium deficiency resulted in hypertrophy of follicular epithelial cells. Moreover, the gene relative expression levels of dio1, dio2, and dio3 showed an increasing trend with the rising concentration of dietary selenium. The transcription levels of HPT axis-related genes (crh, tsh-ß, ttr, tr-s, tpo, nis) and GH/IGF1-related genes (gh, ghr, igf1, igf1r) were significantly upregulated in selenium-supplemented groups. No significant differences in the above indicators were observed between 0.562 and 1.044 mg Se/kg diet group except T3 content and dio1 relative expression ratio. These results indicate that dietary selenium supplementation improves the hepatic DIO activities and thyroid hormone metabolism and regulates the transcription levels of HPT and GH/IGF axis-related genes, which may be responsible for the growth promotion in grass carp.

Differences in growth of Trypanoplasma borreli in carp serum is dependent on transferrin genotype.

Kinetoplastid parasites require transferrin (Tf), being the main source of iron, for growth and multiplication. This group of parasites developed a unique receptor-mediated system for acquiring host Tf which bears no structural homology with the host transferrin receptor. Trypanoplasma borreli, a blood parasite of common carp, probably uses a similar mechanism to sequester iron from host transferrin. In this study, we demonstrate a critical role of Tf for parasite growth. For in vitro studies we isolated and purified Tf from carp homozygous for the D or G allele of Tf. We obtained Tf-depleted serum using specific antibodies to carp Tf and studied gene expression in vivo during T. borreli infection with Real Time-quantitative PCR. We demonstrate that T. borreli cannot survive in medium supplemented with Tf-depleted serum while reconstitution with Tf restores normal growth. The critical role of Tf for parasite survival was shown in incomplete medium (medium without serum): addition of purified Tf significantly increased parasite survival. We also demonstrate that Tf polymorphism has a significant impact on T. borreli multiplication. Cultured parasites die more quickly in an environment containing D-typed Tf, as compared to medium with G-typed Tf. Gene expression during T. borreli infection in carp did not show an acute phase response. We could, however, observe an increased transcription of Tf in the head kidney, which may be associated with an immunological function of the Tf protein.

Effects of dietary marjoram, Origanum majorana extract on growth performance, hematological, antioxidant, humoral and mucosal immune responses, and resistance of common carp, Cyprinus carpio against Aeromonas hydrophila.

The present study aimed to investigate the potential effects of dietary marjoram extract on growth performance, health, and disease resistance in common carp, Cyprinus carpio. To this purpose, the fish were assigned into four treatments and fed by diets supplemented with 0 (control), 100, 200, and 400 mg marjoram extract kg-1 over eight weeks and then challenged with Aeromonas hydrophila. According to the results, 200 mg kg-1 dietary marjoram extract inclusion showed the highest final weight, weight gain, and specific growth rate, and lowest feed conversion ratio (FCR). White blood cell number, Red blood cells, hematocrit, hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin were markedly increased particularly at 200 mg kg-1 treatment. Marjoram extract significantly increased plasma superoxide dismutase activity and decreased malondialdehyde level compared to the control treatment. Plasma complement and lysozyme activities and total immunoglobulin levels, mucosal complement, lysozyme and alkaline phosphatase activities and immunoglobulin levels were significantly increased compared to the control group. The lowest post-challenge survival rate was observed in the control treatment, whereas the highest value was related to the 200 mg kg-1 marjoram treatment. In conclusion, the present study demonstrated that, marjoram extract is a suitable feed supplements for common carp, as it stimulates the fish growth, antioxidant, and immune systems, which suppress the fish mortality during Aeromonas septicemia. According to the results, 200 mg marjoram extract kg-1 is recommended for carp feed formulation.

The blood and mRNA levels of antioxidant-related factors in common carp (Cyprinus carpio) fed p-Coumaric acid.

The natural antioxidants are well known for their antioxidative activity without side effects when compared to antibiotics. Hence, the present study aimed at evaluating p-Coumaric acid as an antioxidant additive on the blood and mRNA levels of antioxidant-related factors in common carp (Cyprinus carpio). Fish fed the basal diet supplemented with p-Coumaric at 0, 0.5, 1, and 1.5 g/kg for 56 days, then the serum, intestine, and liver samples were collected. The growth performance of fish fed with CA showed significantly (P < 0.05) improved FW, WG, and SGR compared to those of the control one. However, the feed conversion ratio was significantly (P < 0.05) reduced in fish fed 1 and 1.5 g/kg diet levels. SOD was not significantly differed among the groups fed with varied p-Coumaric acid (P > 0.05). Serum GPX and TAC were enhanced considerably by p-Coumaric acid regarding the control with the highest being in fish fed 1.5 g/kg diet (P < 0.05). Serum CAT was more elevated in fish provided p-Coumaric acid at 1 or 1.5 g/kg than the control while fish fed 0.5 g/kg did not display significant changes. MDA level significantly decreased by all p-Coumaric acid groups compared to the control one, and the lowest level was observed in 1.5 g/kg (P < 0.05). The mRNA level of CAT was significantly upregulated in the liver by p-Coumaric acid at 1 or 1.5 g/kg (P < 0.05), while the intestine CAT did not influence by p-Coumaric acid (P > 0.05). The measured SOD in the liver and intestine samples revealed no changes in common carp fed p-Coumaric acid (P > 0.05). GPX was significantly upregulated in the intestine by p-Coumaric acid at 1 or 1.5 g/kg (P < 0.05), whereas the liver GPX was upregulated by p-Coumaric acid at 1.5 g/kg. The mRNA level of the GST gene in the intestine of common carp was upregulated by p-Coumaric acid at 1.5 g/kg, whereas the liver displayed upregulated GST in fish fed 1 g/kg diet. The present study approved the application of p-Coumaric acid as a natural antioxidant for friendly, sustainable aquaculture.

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.

The potential benefits of orange peels derived pectin on serum and skin mucus immune parameters, antioxidant defence and growth performance in common carp (Cyprinus carpio).

This study was performed to determine the effects of pectin derived from orange peel (PDOP) on growth performance, antioxidant enzyme activity and serum and skin mucus immune response of common carp (Cyprinus carpio). Common Carp (16.94 ± 0.03 g) were distributed into 12 tanks representing four treatments repeated in triplicates. Four diets were prepared to contain four levels of PDOP as follows: 0 (control), 0.5, 1, and 2% PDOP. Growth and immunological parameters as skin mucus lysozyme activity (SMLA) and total immunoglobulin (SMTIg), serum total immunoglobulin (STIg), serum peroxidase activities (SPA), Catalyse activity (CAT), DPPH radical scavenging activity, specific growth rate (SGR), weight gain (WG), final weight (FW), and feed conversion ratio (FCR) were assessed. Fish fed diets supplemented with PDOP showed an improvement of SGR, WG, FW, and FCR (P < 0.05). In terms of skin mucus immunological parameters, dietary inclusion of pectin significantly (P < 0.05) increased SMTIg. Likewise, carps fed either 1 or 2% PDOP showed notable enhancement of SMLA. In the case of serum immune parameters and antioxidant defence, carps in 1% PDOP treatment showed significantly (P < 0.05) higher SPA and CAT compared to fish fed either control diet or 0.5% OPDP. Additionally, no significant change (P > 0.05) was found in SPA and CAT of fish fed either 1% PDOP or 2% PDOP. Also, no significant (P > 0.05) difference was noticed between treated groups and control in the case of STIg. Furthermore, no significant differences were observed in DPPH radical activity among treatments (P > 0.05). Overall, these results suggested that inclusion of PDOP in common carp diet can beneficially affect growth and immune response.

Ginger (Zingiber officinale) extract affects growth performance, body composition, haematology, serum and mucosal immune parameters in common carp (Cyprinus carpio).

The present study was designed to investigate the dietary effects of ginger extract (Zingiber officinale) on common carp (Cyprinus carpio). Three hundred and sixty fish weighing 10.9 ± 0.17 g were randomly divided into four experimental treatments in triplicates. Four experimental diets were designed containing different inclusion levels of ginger extract as 0% (control), 0.1%, 0.2%, and 0.4% named T1, T2, T3, and T4, respectively, and fish were fed 3% of body weight daily for 60 days. Feed conversion ratio, weight gain, and specific growth rate parameters were measured higher in the groups fed with ginger extract compared to the control, especially in T3 (P < 0.05). Also, fish treated with ginger extract showed lower carcass moisture and lipid, but higher protein contents compared to the control. The results showed significant increase in the number of erythrocytes and leucocytes, as well as the level of hematocrit and hemoglobin in fish fed with supplemented diets. In addition, significant enhancement was observed in cases of serum parameters, including total protein, albumin, globulin, lysozyme, superoxide dismutase, catalase, and total immunoglobulins in T3 and T4 compared to the control. The lowest serum cortisol level was noticed in T3. Furthermore, the T3 group showed the highest activities of skin mucus lysozyme, alkaline phosphatase, and protease (P < 0.05). In conclusion, the present results demonstrated that Zingiber officinale extract at a 0.2% level can effectively improve the growth and health status of Common Carp (Cyprinus carpio).

Dietary supplementation of olive leaf extract increases haematological, serum biochemical parameters and immune related genes expression level in common carp (Cyprinus carpio) juveniles.

The present study investigated the effects of dietary olive leaf (Olea europea L.) extract (OLE) on some blood parameters and immune (TNF-α, IL-1ß and IL-8) related genes in different tissues (head kidney, liver and spleen) and resistance of common carp, Cyprinus carpio to Edwardsiella tarda. Five diets were prepared for fed fish (mean body weight 15.90 ±â€¯0.93 g) with different rates of OLE (0.0%, 0.1%, 0.25%, 0.50% and 1.0%). A control diet was prepared non-supplemented with OLE. Increased haematocrit ratio, serum myeloperoxidase activity, immune response gene levels (IL-1ß in head kidney tissue and TNF-α in spleen tissue) and survival rate against E. tarda particularly in the 0.1% OLE treatment group. In conclusion, results of the present study show that feeding common carp with a diet containing 1 g/kg OLE over a period of 60 days might be adequate to improve fish immune parameters, and survival rate against E. tarda. Therefore, OLE can be used as a dietary additive to prevent E. tarda in common carp.

The effects of common yarrow (Achillea millefolium Linnaeus), cinnamon (Cinnamomum zeylanicum Blume) and rosemary (Rosemarinus officinalis Linnaeus) hydrosols on the some immunological and hematological parameters of common carp (Cyprinus carpio L., 1758).

In this study, the effects of some plant hydrosols (distilled plant waters) based upon some hematological parameters and Nitroblue Tetrazolium (NBT) activities in the common carp (Cyprinus carpio Linnaeus, 1758) infected with Yersinia ruckeri were investigated. In the trial, it was utilized totally 200 common carps with 54.3±6.7 g mean live weight and 15.7±1.8 cm mean total lenght. The 10% rate of the common yarrow (Achillea millefolium Linnaeus) hydrosol; 0.5% rate of the cinnamon (Cinnamomum zeylanicum Blume) hydrosol; and 5% rate of the rosemary (Rosemarinus officinalis Linnaeus) hydrosol were applied to fish as a bath treatment. The erythrocyte (RBC), leukocyte count (WBC), hematocrit value (HCT), haemoglobin amount (Hg), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and activities of NBT in the blood samples taken from the caudal vena of the control and experimental fish groups were analyzed in the 7th, 14th, and 21st days of the exposure treatment. At the end of the research, HCT, Hg, RBC, WBC, MCH and MCV values decreased in the C-2 Group (the control group contain pathogen) compared to the C-1 Group (the control group no contain pathogen), except MCHC value. The NBT activities in the C-1 Groups increased at the 14th day, but decreased quite a few at the 21st day. It has been consequently reached the conclusion that the bath treatments of the some plant hydrosols might be beneficial in increasing of antibacterial properties and in strengthening of defense mechanisms of common carp against Y. ruckeri pathogen.

Effects of dietary organic, inorganic, and nanoparticulate selenium sources on growth, hemato-immunological, and serum biochemical parameters of common carp (Cyprinus carpio).

An 8-week feeding trial was conducted to compare the effects of supplementing (0.7 mg kg-1) different dietary selenium (Se) sources including organic [selenomethionine (SeMet)], inorganic [sodium selenite (Na2SeO3)], and nanoparticulate Se (nano-Se) on physiological responses of common carp, Cyprinus carpio juveniles (9.7 ± 0.1 g). Basal diet without Se supplementation used as control. Fish fed nano-Se supplemented diet had the highest weight gain (97.2 ± 10.8%) and feed efficiency ratio (42.4 ± 0.8%). Intestinal villi height was significantly taller in fish fed nano-Se diet than in the control group in both foregut and midgut sections. Serum glutathione peroxidase and superoxide dismutase activities were significantly higher in nano-Se and SeMet groups than in control and sodium selenite groups. Fish fed Se-supplemented diets had greater red blood cell counts and hematocrit and hemoglobin values than the control group (P < 0.05). Nano-Se and SeMet groups showed a significant increase in white blood cell counts, neutrophil percentage, and serum lysozyme activity than the other groups. Fish fed nano-Se diet had the highest serum hemolytic activity, total immunoglobulin, and total protein and albumin contents, as well as the lowest serum total cholesterol and low density lipoprotein levels (P < 0.05). Overall, significant improvements in growth performance, feed utilization, intestinal morphology, and hemato-immunological and serum biochemical parameters of common carp juveniles suggest nano-Se as an efficient source for providing dietary Se in this species.

Effects of dietary vitamin E deficiency on systematic pathological changes and oxidative stress in fish.

The aim of this study was to investigate the effects of dietary vitamin E deficiency on systematic pathological changes and oxidative stress in fish. A total of 320 healthy common carp (Cyprinus carpio) were randomized into four groups; the control group was fed a basal diet supplemented with 100 IUkg-1 of vitamin E, while the three experimental groups were fed the same basal diet with reduced vitamin E content (0, 25, or 50 IUkg-1). Findings showed that fish in the experimental groups mainly presented with sekoke disease, exophthalmia, leprnorthsis, and ascites. Histopathological and ultrastructural changes comprised nutritional myopathy with muscle fiber denaturation and necrosis, and multi-tissue organ swelling, degeneration, and necrosis. Compared with the control group, RBC count, hemoglobin content, vitamin E concentration, and superoxide dismutase activity were significantly lower in all three experimental groups. However, malondialdehyde content was considerably higher in experimental groups than in the control group. However, there was no difference in glutathione peroxidase activity among groups. In conclusion, dietary vitamin E deficiency (<100 IUkg-1) can cause severe injury and, in particular, oxidative damage in common carp. The oxidative damage might be a main influence caused by vitamin E deficiency in fish. These findings reveal the complete systematic pathological effect of vitamin E deficiency in common carp, which may be applicable to other fish and animals.

Immunostimulatory and growth promoting potential of Tinospora cordifolia (Thunb.) Miers on fingerlings of Amur Carp.

The enhancement of immunity of fish through application of natural immunostimulants would help in minimizing the risk of occurrence of diseases in aquaculture. The present study was designed to evaluate the growth promoting and immunostimulatory effect of Guduchi, Tinospora cordifolia (Thunb.) Miers ex Hook F. leaf powder in fingerlings of Amur carp (Cyprinus carpio haeYnatopterus Martens). The fingerlings were divided into four treatment groups, Ti, T2, T3 and T4. Experimental diets were prepared by mixing rice bran, deoiled mustard cake, soybean meal and vitamin mineral mixture. The leaf powder of T. cordifolia was incorporated into diets D2, D3, and D4 @ 0.25%, 0.5% and 0.75%, respectively. In control diet D1, leaf powder of T. cordifolia was not incorporated. T1 group fishes were fed with D, diet, T2 with D2, T3 with D3 and T4 with D4 @ 5% body weight per day for 90 days. Fingerlings fed with diet D4 achieved significantly improved Specific Growth Rate (1), Feed Conversion Ratio (2.76), and Gross Conversion Efficiency (0.361) as compared .to the control and all other treatments (P <0.05). Hematological and biochemical parameters, total leuckocyte count (53.849x103/[L), total erythrocyte count (3.50x106/iL), hemoglobin concentration (17.17%), total serum protein, albumin and globulin (12.35, 1.56 and 10.78 g/dL) in D4 diet fed fishes showed increase as compared to the control and all other treatments (P <0.05). The above research revealed that Tinospora cordifolia leaf powder has significant growth promoting and immunostimulatory potential in Amur carp raising.

Effects of dietary ß-(1,3)(1,6)-D-glucan supplementation on growth performance, intestinal morphology and haemato-immunological profile of mirror carp (Cyprinus carpio L.).

In recent years, aquaculture research has focused on probiotics, prebiotics, and ß-glucans, in order to improve health status and growth performance. Information regarding the effects of ß-glucan on growth performance and intestinal immunity of mirror carp (Cyprinus carpio L.) is scarce. An experiment was therefore conducted to investigate the effects of a yeast ß-glucan preparation (MacroGard(®) ) on growth performance, intestinal morphology and haemato-immunological indices of mirror carp. Carp (initial weight 11.1 ± 0.0 g) were fed highly purified diets supplemented with 0% (control), 0.1%, 1% or 2% MacroGard(®) for 8 weeks. Fish fed diets containing 1% and 2% MacroGard(®) showed significant improvements in weight gain, specific growth rate and feed conversion ratio compared to fish fed both the control and the 0.1% MacroGard(®) containing diet. Histological appraisal of the intestine showed a significantly higher infiltration of leucocytes into the epithelial layer of fish fed diets supplemented with 1% and 2% MacroGard(®) in the anterior intestine compared to fish fed the control and 0.1% MacroGard(®) diet. This effect was not observed in the posterior intestine. There were no significant differences in the intestinal absorptive surface area and number of goblet cells in either intestinal region. At the end of the experiment, the haematological status of the fish was examined. Compared to control fed fish, the haematocrit value was significantly elevated in fish fed the 2% MacroGard(®) diet. Furthermore, the blood monocyte fraction was significantly higher in fish fed the 1% and 2% MacroGard(®) diets. No significant changes were observed in the other blood parameters assessed. The present study shows that high dietary ß-glucan inclusion increases growth performance without detrimental effects on the health indicators assessed. Increased intraepithelial leucocytes in the anterior intestine may indicate a localized immune response; no detrimental effects on intestinal morphology were observed.

Antioxidant status of serum, muscle, intestine and hepatopancreas for fish fed graded levels of biotin.

Lipid peroxidation, protein oxidation and antioxidant activities of muscle, intestine, hepatopancreas and serum in juvenile Jian carp (Cyprinus carpio var. Jian) were investigated after feeding graded levels of biotin (0.010, 0.028, 0.054, 0.151, 0.330, 1.540 and 2.680 mg kg(-1) diet) for 63 days. Both malondialdehyde and protein carbonyl content in all studied tissues and serum were the lowest in fish fed diets containing 0.151-0.330 mg biotin kg(-1) diet and then increased in fish fed the diet with 2.680 mg biotin kg(-1) diet (P < 0.05). Similarly, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities in serum significantly decreased with biotin levels up to 0.151 mg kg(-1) diet (P < 0.05). Conversely, capacities of anti-hydroxyl radical (AHR) and anti-superoxide anion (ASA) in the detected tissues and serum significantly improved with biotin levels up to 0.054-1.540 mg kg(-1) diet and then decreased in 2.680 mg biotin kg(-1) diet group for muscle and intestinal AHR as well as hepatopancreas ASA (P < 0.05). Activities of superoxide dismutase in all studied tissues and serum significantly elevated with biotin levels up to 0.330 mg kg(-1) diet and then decreased when fish fed the diet with 2.680 mg biotin kg(-1) diet, except intestine (P < 0.05). Meanwhile, activities of catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase and total thiol content in all studied tissues and serum showed the upward trend with biotin supplementations (P < 0.05). These results indicated that biotin improved antioxidant status and depressed lipid peroxidation and protein oxidation in all studied tissues and serum.

Zinc transferrin stimulates red blood cell formation in the head kidney of common carp (Cyprinus carpio).

The common carp is one of the few fish able to tolerate extremely low oxygen levels. These fish store zinc in their digestive tract tissue and head kidney at concentrations of 300-500µg/g of fresh tissue, which is 5-10 times higher than in other fish. Previous studies have indicated a link between the high zinc levels in the common carp and stress erythropoiesis. In this report, using suspension-cultured common carp head kidney cells with or without ZnCl2 supplementation, we found that zinc stimulated the proliferation of immature red blood cells; however, this effect was only observed when the culture was supplemented with carp serum. We identified the active component of carp serum to be transferrin. The zinc-transferrin complex interacts with the transferrin receptor and stimulates the proliferation of immature red blood cells. In addition, the growth rate of the immature red blood cells was regulated by the supplied ZnCl2 concentration. Under stress, the zinc in the common carp digestive tract tissue was released and used as a signal to induce red blood cell formation in the head kidney. This cell culture system might provide a means for exploring the regulatory role of zinc in hematopoietic cell growth.

Dietary tryptophan changes serum stress markers, enzyme activity, and ions concentration of wild common carp Cyprinus carpio exposed to ambient copper.

Effect of dietary tryptophan (TRP) on copper toxicity was investigated in common carp, Cyprinus carpio. Fish were randomly distributed into two triplicate treatments (control and TRP) and fed control (TRP = 3.1 g kg(-1)) or TRP (TRP = 8.1 g kg(-1)) diets over a 2-week period. Then, both treatments were subjected to 10 mg l(-1) copper sulfate over a 7-day period. Mortality and serum cortisol, glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), sodium, potassium, and chloride levels were recorded at 0, 24, 72, 120, and 168 h post-copper exposure. There was no mortality in the TRP group, whereas the control group mortality was started at 120 h post-copper exposure (21.7 ± 7.6 %) and reached 61.7 ± 10.4 % at the end of the experiment. Cortisol, glucose, ALT, and AST levels significantly (P < 0.05) increased after copper exposure in both groups; however, the control group showed significantly higher levels than the TRP group. In both groups, sodium decreased after copper exposure and did not return to the pre-exposure values. Potassium levels significantly increased 24 h post-copper exposure in both groups and remained significantly elevated in the control group at 72 h, when fell to the pre-exposure values in the TRP group. No significant changes were observed in the chloride levels in any groups. It is concluded that dietary TRP is capable to increase common carp tolerance to copper toxicity via mitigating copper-induced stress rather than restoring gill dysfunction and hydromineral imbalance.

In vitro and in vivo hepatoprotective and antioxidant effects of Astragalus polysaccharides against carbon tetrachloride-induced hepatocyte damage in common carp (Cyprinus carpio).

The present study is aiming at evaluating the hepatoprotective and antioxidant effects of Astragalus polysaccharide (APS) on the carbon tetrachloride (CCl(4))-induced hepatocyte and liver injury in common carp in vitro and in vivo. In vitro, APS (200, 400 and 800 µg/ml) was added to the carp primary hepatocytes before (pre-treatment), after (post-treatment) and both before and after (pre- and post-treatment) the incubation of the hepatocytes with CCl(4) at 8 mM in the culture medium. APS at concentrations of 200, 400 and 800 µg/ml significantly improved cell viability and inhibited the elevation of glutamate pyruvate transaminase (GPT), glutamate oxalate transaminase (GOT), lactate dehydrogenase (LDH) and malondialdehyde (MDA) and significantly increased the reduced level of superoxide dismutase (SOD). In vivo administration of APS at the doses of 1.5 and 3 g/kg in the diet for 60 days prior to CCl(4) intoxication significantly reduced the elevated activities of GPT, GOT and LDH and increased the reduced levels of total protein and albumin in the serum; meanwhile, the reduced levels of SOD, glutathione and total antioxidant capacity (T-AOC) were markedly increased and the MDA formation was significantly inhibited in liver tissue. Overall results proved the hepatoprotective action of APS, which is likely related to its antioxidant activity. The results support the use of APS as a hepatoprotective and antioxidant agent in fish.

Toxicity of Moringa oleifera seed extract on some hematological and biochemical profiles in a freshwater fish, Cyprinus carpio.

The study was carried out to investigate the acute and sublethal toxicity of Moringa oleifera seed extract on hematological and biochemical variables of a freshwater fish Cyprinus carpio under laboratory conditions. The 96 h LC50 value of M. oleifera seed extract to the fish C. carpio was estimated by probit analysis method and was found to be 124.0 mg/L (with 95% confidence limits). For sublethal studies a non lethal dose of 1/10th of 96 h LC50 value (12.40 mg/L) was taken. During acute treatment (96 h), hematological variables like red blood cell count (RBC), hemoglobin (Hb), hematocrit (Hct), and mean corpuscular hemoglobin concentration (MCHC) were significantly (P<0.05) decreased in fish exposed to seed extract. However a significant (P<0.05) increase in white blood cell count (WBC), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) value was observed in the exposed fish during above treatment period when compared to that of the control groups. Biochemical parameters such as plasma protein and glucose levels significantly declined in fish exposed to seed extract while a significant (P<0.05) increase in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activity was observed. During sublethal treatment (12.40 mg/L), WBC count, MCV, MCH, plasma glucose, AST, ALT and ALP activities were gradually elevated (P<0.05) at the end of 7, 14, 21, 28 and 35th days in seed extract exposed fish, whereas plasma protein level declined. However, a biphasic trend was noticed in Hb, Hct, RBC and MCHC levels. This study may provide baseline information about the toxicity of M. oleifera seed extract to C. carpio and to establish safer limit in water purification.

Effects of neurotoxin - anatoxin-a on common carp (Cyprinus carpio L.) innate immune cells in vitro.

OBJECTIVES: The aim of this study was to determine if cyanoneurotoxin - anatoxin-a (ANTX-a) alters the essential functions of innate immune cells such as free radicals generation in phagocytic cells and phagocytosis. DESIGN: In the experiments pure ANTX-a was used at concentrations of 0.01, 0.05, 0.1 and 1 µg/ml RPMI-1640 medium. Phagocytes were isolated from carp blood and pronephros. Relative changes in intracellular total free radical presence in fish phagocytes were monitored using a fluorescent probe, dichlorodihydrofluorescin DiOxyQ (DCFH-DiOxyQ) which detects hydrogen peroxide (H2O2), nitric oxide (NO), peroxyl radical and peroxynitrite anion. Phagocytic activity of fish leukocytes was analyzed with a Vybrant phagocytosis assay kit. RESULTS: The H2O2 level generated in response to ANTX-a at the highest used concentration was significantly suppressed in pronephros but not in blood phagocytes. Moreover, it was observed that generation of superoxide radicals and nitrite formation was significantly increased in blood and pronephros phagocytes after incubation with lower concentrations of the neurotoxin. The phagocytosis of fish leukocytes was significantly reduced at the two highest used toxin concentrations (0.1 and 1 µg/ml medium). CONCLUSION: This findings suggests that ANTX-a could change innate immunity and reduced adaptive immunity after stress induced by cyanobacterial blooms.