Coriolus versicolor polysaccharides enhance the immune response of crucian carp (Corassius auratus gibelio) and protect against Aeromonas hydrophila

To investigate the effect of Coriolus versicolor polysaccharides (CVPS) on the immune response of crucian carp (Corassius auratus gibelio), fish were fed diets containing CVPS at different concentrations including 0.5, 1.0 and 2.0 g kg^?1 for 5 weeks. Other groups of fish were vaccinated by intraperitoneal injection (i.p.) against Aeromonas hydrophila with a killed bacterin at the beginning of the experiment and fed the same diets as described above. Additionally, control fish and vaccinated‐only fish were fed basal diets without CVPS supplementation. The phagocytosis, lysozyme activity, complement components C3 and C4, E‐C3bRR (Erythrocyte‐C3b rosette rate) and E‐CIRR (Erythrocyte‐immune complex rosette rate) levels and circulating antibody titers in the serum were monitored. Five weeks after feeding the prescribed diet, fish were challenged with A. hydrophila and the mortalities recorded. Results showed that feeding non‐vaccinated and vaccinated crucian carp with CVPS stimulated the phagocytosis of leukocytes, lysozyme, complement components C3 and C4, erythrocyte immune adherence, and circulatory antibody titers in serum in vaccinated crucian carp. Immune parameters increased to their highest levels after 3 weeks of feeding the diet containing 0.5 or 1.0 g kg^?1 CVPS. These doses also resulted in the highest protection in the challenge experiment. Best survival (85%) was in the vaccinated group fed the diet containing 1.0 g kg^?1 CVPS, whereas almost 80% of control fish (negative control) and 50% of vaccinated‐only fish (positive control) died.     

Effects of intraperitoneal injection of cortisol on non‐specific immune functions of Ctenopharyngodon idella

After grass carps Ctenopharyngodon idellus were injected with cortisol, with (CBC) and without (C) a cocoa butter carrier, the effects of both slowly and rapidly acting exogenous cortisol on their non‐specific immune functions were investigated. On the one hand, after injection with CBC, the cortisol concentration and lysozyme activity in fish serum were enhanced and were sustained at high levels for a long period (30 days). The killing activity in the serum declined with time, and phagocytosis of head kidney macrophages diminished significantly (P < 0·05 or P < 0·01). The leukocrit values in the high dose group (31·8 mg cortisol fish^?1) increased over time, however, with the maximum average being 5·6% at day 30. The spleen mass index in the high dose group was 0·93 × 10^?3 after 30 days, notably lower (P < 0·05) than that in the control group. In addition, a decrease in resistance to Aeromonas hydrophila infection in cortisol‐treated fish was shown, with the final cumulative mortalities being 54·5 and 66·7% in the low and high dose groups, respectively. On the other hand, there was a decrease in both serum cortisol concentration and lysozyme activity of the experimental fish within 2 weeks after injection with C, where plasma bactericidal activities in the high dose group (31·8 mg cortisol fish^?1) were remarkably lower (P < 0·01) than those in the control group at each sampling, but were increased slightly over time. The results of which were different from those in the CBC trial. Phagocytic activity of head kidney macrophages and spleen mass index decreased significantly (P < 0·05), while there were increases in leukocrit value and cumulative mortality due to A. hydrophila. The results of which were similar to those in the CBC trial. This study indicated that the injection of cortisol depressed the non‐specific immune functions of the grass carp and increased its susceptibility to disease.     

Orally administered LPS enhances head kidney macrophage activation with down-regulation of IL-6 in common carp (Cyprinus carpio)

Immunostimulants represent a promising aquaculture tool for enhancing disease and stress resistance in cultured fish. Moreover, the term and dose for acting immunostimulants is an important thing for fish farmer. This study investigated the immune parameters of common carp after oral administration of LPS (5, 10, 20 μg/kg/days) for 30 and 60 days, which is considered to be the proper time period for acting in aquaculture. Phagocytic and bactericidal activities of head kidney macrophages and serum lysozyme activities were significantly enhanced in LPS-fed carp. Orally administered LPS augmented the expression of interleukin (IL)-1β and TNF-α mRNAs but reduced the expression of IL-6 mRNA in head kidney. Although LPS was detected in the serum and liver after a high-dose (>15 mg/kg) oral administration, it was not detected by administered LPS-specific ELISA after a low-dose (<20 μg/kg) administration. It is speculated that orally administered LPS enhances the eliminating functions of head kidney macrophages with down-regulation of IL-6.     

Non-specific immune responses in juveniles of Indian major carps

The non‐specific immune parameters are useful to determine the health status of fish and to evaluate the immunomodulatory substances for fish farming as markers of pollution and disease resistance. Some of the important parameters, viz. superoxide production by neutrophils through nitroblue tetrazolium (NBT) assay; haemagglutination (HA), haemolysin (HLY) and bacterial agglutination titres; myeloperoxidase (MPO), and lysozyme activities, and alternative complement levels in serum of the juveniles of three Indian major carp species (Cirrhinus mrigala, Catla catla and Labeo rohita) were measured to establish their physiological normal range. A wide variation among the individuals within a species in the ranges of the most of the immune parameters was recorded. Significantly higher levels in the mean values of HA, HLY, bacterial agglutination titres; superoxide production by neutrophils in nitroblue tetrazolium assay; serum MPO and lysozyme activities, i.e. 371.20, 4.60, 18.80, 0.40, 0.62 and 6.55 μg ml^?1, respectively, were obtained in L. rohita except a much lower alternative haemolytic complement activity (29.06 units ml^?1) compared with the other two species. In most of the parameters, L. rohita showed the highest value, possibly indicating its more natural resistance compared with the other two species.     

Immunostimulatory activities of specific bacterial secondary metabolite of Anoxybacillus flavithermus strain SX‐4 on carp,Cyprinus carpio

Aims: To determine the capacity of secondary metabolite of strain SX‐4, to enhance the nonspecific immunity and survival of carp (Cyprinus carpio), and to identify the constituents that are responsible. Methods and Results: A thermophilic strain SX‐4 that is able to produce immunostimulatory metabolite was isolated from sludge sample of hot spring and identified by comparison with 16S rRNA sequences (99% of homology) as Anoxybacillus flavithermus. Bioactivity‐guided fractionation of methanol extract from its cell‐free culture, one bacterial peptide with the capacity of improving the nonspecific immune responses and disease resistance (relative per cent survival = 66·67%) was obtained and the compound was characterized as cyclo‐(L‐Pro‐Gly) by IR, ESI‐MS, ¹H NMR and ¹³C NMR spectroscopic analyses. After intraperitoneal administration of this peptide, selected innate immune parameters including phagocytic activity, superoxide anion production, serum lysozyme activity and serum SOD activity, along with immune‐related genes expression (i.e. interleukin‐1β and inducible nitric oxide synthase), in the blood were found to be significantly increased. Conclusions: The bacterial peptide cyclo‐(L‐Pro‐Gly) significantly enhances nonspecific immunity and survival of carp. Significance and Impact of the Study: There is a possibility of using cyclo‐(L‐Pro‐Gly) as a better natural immunostimulant, which could have a promising role in aquaculture to prevent diseases and disease outbreaks.     

Influence of feeding the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on the non-specific cellular and humoral defence mechanisms of rainbow trout (Oncorhynchus mykiss)

Previous studies have shown that leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB) increases the immune function in animals as measured by cellular and humoral immune responses. In the present study the influence of feeding HMB on the nonspecific cellular and humoral defence mechanisms and protection against furunculosis in rainbow trout (Oncorhynchus mykiss) was examined. HMB was fed in a pelleted ration at either 0 (control), 10, 25 or 50 mg  kg^?1 bw day^?1 for 8 weeks. Blood and pronephros cells were taken at random from 10 fish in each group for the analyses. The respiratory burst activity (RBA) and potential killing activity (PKA) of phagocytes, lymphocyte proliferation stimulated by either concanavalin (ConA) or lipopolysaccharide (LPS), lysozyme activities and total immunoglobulin (Ig) levels in plasma were analysed at 0, 1, 2, 3, 4, 6 and 8 weeks. After 4 weeks of feeding HMB, a challenge test was performed by injection of Aeromonas salmonicida into the fish. HMB approximately doubled the respiratory burst activity and potential killing activity ability of polymorphonuclear (PMN) and morphonuclear (MN) cells (P < 0.01) and increased the mitogen‐stimulated lymphocyte proliferation (P < 0.01) when compared with the control group. HMB feeding also increased (P < 0.01) the lysozyme activity in plasma and total Ig levels in serum. During the 14‐day challenge test, mortality was decreased (P < 0.01) by up to 62% in HMB‐fed fish compared with the control group mortality. In conclusion, the non‐specific immune enhancement by HMB resulted in protection against furunculosis in the rainbow trout.     

Non‐specific immunity and disease resistance are enhanced by the polysaccharide fraction of a marine chlorophycean macroalga in Oreochromis niloticus (Linnaeus, 1758)

Polysaccharides (PF) from marine macroalgae, Caulerpa scalpelliformis were extracted and tested for its potential immunostimulatory and disease resistance properties in fish. Five groups of Nile tilapia (n = 6), Oreochromis niloticus (Linnaeus, 1758) were intraperitoneally administered with the different doses of PF (2, 20 or 200 mg/kg body weight) or with yeast‐derived commercial immunostimulant, Macrogard^? (20 mg/kg body weight), to compare the effectiveness. An untreated control group was also maintained. A total of fifteen fibre reinforced plastic tanks (150 L, ambient temperature and light conditions) were used, with triplicate tanks for each group. Only four fish per tank (totally 12 fish from a group) were taken at random and assayed. PF enhanced all the tested non‐specific serum immune responses namely lysozyme, myeloperoxidase, antiprotease, and bactericidal activities. There was an upregulation of the genes encoding IL‐1β, lysozyme and TNF‐α in the spleen of PF injected fish as compared to the control group. In order to study the overall functional immunity, disease resistance test was conducted. Another five groups of fish (n = 10) were treated by intraperitoneal injection with different doses of PF or Macrogard^? or untreated as mentioned earlier in triplicates (30 fish per group in three tanks, totally 150 fish in 15 tanks). Seven days post treatment, fish were challenged by intraperitoneal administration of live virulent Aeromonas hydrophila. PF treated fish were protected with significant reduction in the mortality and the consequent increased relative percent survival (RPS) of 92 in the least (2 mg/kg) and middle dose (20 mg/kg) groups. The disease resistance experiment was repeated again but this time, fish were challenged 21 days post treatment that resulted in RPS of 50 for the middle dose. The results clearly show that the intraperitoneal administration of the polysaccharide fraction had a stimulating effect on the non‐specific immune responses, immune gene expression and disease resistance.     

Effects of human chorionic gonadotropin (hCG) and handling stress on spermiation of silver perch Leiopotherapon plumbeus (Kner, 1864)

This study determined the effect of human chorionic gonadotropin (hCG) and handling stress on the spermiation and milt response of silver perch Leiopotherapon plumbeus based on the measurement of spermatocrit, sperm density, and milt production. Compared to saline‐injected fish, the mean spermatocrit (or packed sperm) of hCG‐treated fish was significantly lower at 18 h (47.9%) and 30 h (40.2%) post‐injection while mean sperm density was significantly lower at 30 h post‐injection (3.6 × 10⁶ cells μl^?1) but not at 18 h. At 18 h (1.8 μl g‐BW^?1) and 30 h (2.5 μl g‐BW^?1) post‐injection, mean milt production of hCG‐treated fish was significantly higher than in the saline group. Milt consistency was also thinner in the hCG‐treated group. Mean sperm density of handled fish (18.0 × 10⁶ cells μl^?1) was significantly lower than control fish (23.4 × 10⁶ cells μl^?1). However, mean sperm density of handled plus saline‐injected (16.2 × 10⁶ cells μl^?1) and handled plus hCG‐treated fish (8.4 × 10⁶ cells μl^?1) was significantly lower than in the control goup. Having thicker milt consistency, mean spermatocrit and milt production of handled (77.5%; 1.1 μl g‐BW^?1, respectively) and handled plus saline‐injected fish (75.4%; 1.1 μl g‐BW^?1, respectively) were not significantly different from the control fish (76.2%; 1.3 μl g‐BW^?1, respectively). Handled plus hCG‐treated fish had the lowest mean sperm density (8.4 × 10⁶ cells μl^?1) and spermatocrit (54.7%), but had the highest mean milt production (5.5 μl g‐BW^?1) among the treatment groups. These results demonstrate that the hCG injection effectively induces spermiation and milt expression and that handling‐related stress negatively affects such responses. The spermatocrit method may be used to assess the spermiation and milt response of silver perch.     

Effect of probiotic Bacillus subtilis Ch9 for grass carp,Ctenopharyngodon idella (Valenciennes, 1844), on growth performance,digestive enzyme activities and intestinal microflora

In the present study, Bacillus subtilis Ch9 was evaluated as a probiotic in grass carp, Ctenopharyngodon idella (Valenciennes, 1844). For 56 days the grass carp (50 ± 2.5 g) were given a feed containing B. subtilis Ch9 in three concentrations: 1.0 × 10⁹ (T₁), 3.0 × 10⁹ (T₂) and 5.0 × 10⁹ (T₃) CFU kg^?1 feed in triplicate treatments. The control group (T₀) was given feed without B. subtilis Ch9 for the same period. Determined were the specific growth rate (SGR), feed conversion ratio (FCR), and digestive enzyme activities in the intestine and hepatopancreas as well as the intestinal microflora. After 56 days, fish receiving the diets supplemented with B. subtilis Ch9 showed significantly higher SGR and lower FCR (P < 0.05) than those fed the control diet. There was no significant different in SGR and FCR among T₁, T₂ and T₃ nor was the survival rate affected (P > 0.05) by the dietary treatments. From days 14 to 56 of the experiment, higher protease, amylase and lipase activities in the foregut, midgut hindgut and hepatopancreas were observed in T₁, T₂ and T₃ (P < 0.05) compared with the control over a short‐term (14–28 days). Enzyme activity did not increase after long‐term feeding with B. subtilis Ch9 (56 days), but was still higher than that of control fish (P < 0.05). Fish fed the probiotic had an increase in trend of total aerobic and facultative anaerobic bacterial quantity (P > 0.05), but the ratio of Bacillus was significantly higher (P < 0.05) than in control fish. The total anaerobic bacterial quantity, Bifidobacterium and Lactobacillus were significantly higher (P < 0.05) in fish fed B. subtilis Ch9 compared with fish fed control feed. In conclusion, an optimum dose of B. subtilis Ch9 could modulate intestinal microflora, induce digestive enzyme activity and potentially promote the digestion and absorption of nutrients, as well as improve the growth performance of grass carp significantly.     

Antagonistic activity of two potential probiotic bacteria from fish intestines and investigation of their effects on growth performance and immune response in rainbow trout (Oncorhynchus mykiss)

The probiotic activity of two bacterial strains, Lactobacillus casei and Lactobacillus plantarum, isolated from common carp intestines was studied using antagonistic tests in vitro against Yersinia ruckeri. Randomly assigned to triplicate groups were 450 rainbow trout (mean weight, 20 ± 3 g) fed three different diets: a commercial feed, or the same feed incorporated into either 5 × 10⁷ CFU g^?1 of L. casei or L. plantarum. After a 30‐day feeding trial, 30 fish in each group were challenged with Yersinia ruckeri by intraperitoneal injection. Growth parameters were significantly increased in both treatment groups. Immune parameters such as lysozyme activity, alternative complement activity and total immunoglobulin level were significantly higher in the L. casei group than in fish fed the control diet, while no significant differences were revealed between the L. plantarum and control groups. Mortality rates of fish fed L. casei and L. plantarum were lower than in fish fed the control diet after challenging with Y. ruckeri.     

Immunostimulant effects of Cotinus coggyria on rainbow trout (Oncorhynchus mykiss)

In this study, non-specific immune effects of tetra (Cotinus coggyria) on rainbow trout (Oncorhynchus mykiss) by dietary intake were investigated. Fish were fed daily ad libitum with diets containing 0.5% and 1.0% tetra for 3 weeks. After this period, fish were switched back to the basal diet for additional 6 weeks. Extracellular and intracellular respiratory burst activities, phagocytosis in blood leukocytes, lysozyme activities, and total plasma protein levels were evaluated at the end of the tetra feeding period and every 3 weeks during the basal diet period. Extracellular and intracellular respiratory burst activities, phagocytic activity, lysozyme activity and total protein level parameters of the groups containing 0.5% and 1.0% tetra were higher than the control group at the end of the 3rd, 6th and 9th weeks, respectively (P < 0.05). The highest values of the non-specific immune parameters were observed in the group fed with 1.0% tetra. Tetra groups did not show any significant difference (P > 0.05) in terms of specific growth rate and average weight of the fish.     

The granulocyte colony-stimulating factors (CSF3s) of fish and chicken

Granulocyte colony-stimulating factor (CSF3) is a glycoprotein cytokine, which influences the hematopoiesis of the phagocytic neutrophils and its precursors and was used extensively in cancer therapy and for the treatment of neutropenia in mammals. However, CSF3 is yet to be identified in nonmammalian species mainly because of its rapid mutation. Here, we report the first CSF3 genes from three teleost fishes: Japanese flounder (Paralichthys olivaceus), fugu (Takifugu rubripes), and green-spotted pufferfish (Tetraodon nigroviridis) and present evidence that the chicken (Gallus gallus) myelomonocytic growth factor is in fact the chicken CSF3 orthologue. We support this by showing significant conservation of the CSF3 genes’ structure, domains, regulatory motifs, and synteny across species and by phylogenetic analysis. CSF3 orthologues are indeed evolving rapidly and appears to be undergoing purifying selection in mammals but positive selection in fish and chicken. Furthermore, the paralogous fugu and pufferfish CSF3-1s and CSF3-2s are shown to be the ancestral and duplicate genes, respectively. Finally, we demonstrate that the Japanese flounder CSF3 gene is at least involved in immunity based on its basal expression in immune-related tissues and its upregulation in kidney and peripheral blood leukocytes after in vitro stimulation with lipopolysaccharide and a combination of concanavalin A/phorbol myristate acetate.Electronic Supplementary Material Supplementary material is available for this article at ()     

Interaction of benzo[a]pyrene, 2,3,3′,4,4′,5 hexachlorobiphenyl (PCB 156) and cadmium on biomarker responses in flounder (Platichthys flesus L.)

Interactive effects of a mixed pollutant exposure on biomarker responses were studied in European flounder (Platichthys flesus L.). The model chemicals, benzo[a]pyrene (BaP, 2.5 mg kg^-1), 2,3,3′,4,4′5 hexachlorobiphenyl (PCB-156, 2.5 mg kg^-1), and cadmium (cadmium, 1 mg kg^-1), were administered to fish by subcutaneous injections. Biomarker responses were quantified both following administration of single chemicals and sequential combinations of the chemicals in pairs. Significant induction of CYP1A protein levels and corresponding ethoxyresorufin-O-deethylase (EROD) activities was observed in BaP and PCB treated flounder after 2 and 8 days, respectively. The strongest induction (44 fold) was caused by BaP. No further induction was observed after additional treatment with PCB 156. CYP1A induction caused by BaP was inhibited (40% compared with BaP treatment alone) in flounder pre treated with cadmium, whereas induction by PCB 156 appeared to be unaffected by pre treatment with cadmium. Flounder treated with cadmium only had significantly elevated hepatic levels of metallothionein (MT) after 15 days. Pre treatment with BaP and PCB prior to cadmium inhibited the MT induction (30-50%) compared with cadmium alone. Furthermore, significantly higher glutathione S transferase activities were observed in flounder administered cadmium alone, and in flounder treated with BaP or PCB 156 prior to cadmium. GST selenium independent peroxidase activities appeared to be unaffected by any of the treatments in the present study. The results indicate that chemical mixtures may affect biomarker responses differently from compounds administered alone, and that the sensitivity of both CYP1A and MT are influenced by pollutants other than their primary inducers.     

Life history characteristics of an invasive cyprinid fish (Carassius gibelio) in Chimaditis Lake (northern Greece)

The life history characteristics of an invasive cyprinid fish, the Prussian carp (Carassius gibelio) were examined in Lake Chimaditis (northern Greece). The population is dominated by females that are able to reproduce gynogenetically. Fish samples were collected using trammel nets from August 2004 to July 2005. Their total length (TL) ranged between 21.9 and 37.0 cm. The length–weight relationship was W = 0.0336TL^2.81 (r² = 0.92, n = 600) and the mean Fulton condition factor exhibited monthly variation from 0.172 (May) to 0.186 (August). According to the annual growth marks present, the lifespan of the Prussian carp in Lake Chimaditis is 6 years. The growth parameters were estimated as L_∞ = 34.46 cm, K = 0.297 year^?1, t₀ = ?1.994 year. Absolute fecundity (F_A) ranged between 26 000 and 176 600 oocytes (mean = 66990) and relative fecundity between 78 and 251 oocytes per gram of total weight (mean = 158). Absolute fecundity increased exponentially with length (F_A = 0.286 × TL^3.66, r² = 0.66) and weight (F_A = 17.93 × W^1.36, r² = 0.73) of the fish.     

Propolis and Herba Epimedii extracts enhance the non-specific immune response and disease resistance of Chinese sucker,Myxocyprinus asiaticus

The effect of traditional Chinese medicine (TCM) formulated from propolis and Herba Epimedii extracts at the ratio of 3:1 (w/w) on non-specific immune response of Chinese sucker (Myxocyprinus asiaticus) was investigated. Fish were fed diets containing 0 (control), 0.1%, 0.5% or 1.0% TCM extracts for five weeks. The respiratory burst and phagocytic activities of blood leukocytes, lysozyme and natural haemolytic complement activities in plasma were measured weekly. After five weeks of feeding, fish were infected with Aeromonas hydrophila and mortalities were recorded. Results of this study showed that feeding Chinese sucker with different dosage of TCM extracts stimulated respiratory burst activity, phagocytosis of phagocytic cells in blood and lysozyme activity in plasma. They had no effect on plasma natural haemolytic complement activity. All dosage of treated groups showed reduced mortality following A. hydrophila infection. Feed containing 0.5% TCM extracts was the most effective with the mortality of the fish significantly reduced by 35% compared to the control. The results indicate that propolis and Herba Epimedii extracts in combination enhances the non-specific immune response and disease resistance of Chinese sucker against A. hydrophila.     

无花果多糖对鲫鱼非特异性免疫功能的影响

实验研究了无花果多糖对鲫鱼非特异性免疫功能的影响。将鲫鱼分成A0、A1、A2、A3和A4五个组,其中A0组投喂基础饵料,设为对照组,而A1、A2、A3和A4分别投喂添加0.1%、0.2%、0.4%、0.8%无花果多糖的基础饵料,并在试验的第0、第7、第14、第21、第28、第35天检测鲫鱼血清补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性。结果表明,A2组的补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性显著高于A0组(P3组补体C3含量、SOD活性和血液白细胞吞噬活性极显著的高于A0组(P1组、A4组(P3组补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液中白细胞吞噬活性与A2组相比差异不显著。A0组、A1组和A4组之间的补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性无显著差异(P>0.05)。       

Dietary Administration of Probiotic Aeromonas veronii V03 on the Modulation of Innate Immunity,Expression of Immune-Related Genes and Disease Resistance Against Aeromonas hydrophila Infection in Common Carp (Cyprinus carpio)

This study investigates the effects of dietary Aeromonas veronii V03 supplementation on growth performances, innate immunity, and expression of immune-related genes in lymphoid organs of Cyprinus carpio and resistance to Aeromonas hydrophila infection. Fish were fed for 4 weeks with basal diet (BD; without probiotic), and experiment diet containing different doses of A. veronii V03 at 3.2 × 10⁷ (DI) and 3.5 × 10⁹ (DII) CFU g⁻¹ of diet. At the end of the probiotic feeding trial, fish were challenged with A. hydrophila, and the percentage of survival rates was recorded over 7 days. Results revealed that fish fed with A. veronii V03 demonstrated a significant improvement in growth and enhancement of innate immunity, including respiratory burst, myeloperoxidase, and lysozyme activities, and total immunoglobulin level compared with BD fed to fish. Relatively, expression of cytokines (MyD88, IL-1β1, IL-8, and IL-10) and c- and g-type lysozymes were significantly up- and downregulated in lymphoid organs of fish. Moreover, dietary supplementation of A. veronii V03 exhibited significantly (p < 0.001) higher survival rates of DI (90%) and DII (96.66%) compared with BD (53.33%) fed fish against A. hydrophila infection. These findings help to understand the effects of probiotic A. veronii V03 administrated feed influences on growth and ailment resistance to A. hydrophila infection by regulating innate and systemic immunity in common carp fish.

     

Dietary Macrogard reduces <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis> mortality in tench (<Emphasis Type="Italic">Tinca tinca</Emphasis>) through the activation of cellular and humoral defence mechanisms

Influence of beta-1.3/1.6-glucan (Macrogard) on the innate immunity and protection against Aeromonas hydrophila in tench (Tinca tinca (L.)) was assessed. Macrogard was fed at doses of 0, 0.5, 1 and 2 g kg⁻¹ of pellets for 1 month. The blood, spleen and head kidney from 10 fish of each group were separated and analysed for immunity parameters. Twenty tench from each group were infected with A. hydrophila. Macrogard at doses 1 and 2 g kg⁻¹ of feed significantly (P < 0.05) increased the phagocytic activity of macrophages and proliferative response of mitogens stimulated lymphocytes. The same doses significantly (P < 0.05) increased lysozyme activity and Ig level in serum, compared to the control and dose 0.5 g kg⁻¹ of feed. The challenge test showed that Macrogard reduced mortality of tench after experimental infection (5–35%).     

A molecular approach to detect hybridisation between crucian carp (Carassius carassius) and non-indigenous carp species (Carassius spp. and Cyprinus carpio)

1. Releases of non‐native fish into the wild is an increasing problem posing considerable ecological and genetic threats through direct competition and hybridisation. 2. We employed six microsatellite markers to identify first generation hybrids and backcrosses between native crucian carp (Carassius carassius) and introduced goldfish (C. auratus) and common carp (Cyprinus carpio) in the U.K. We also investigated the genetic characteristics of the taxonomically controversial gibel carp (Carassius spp.) from sites across Europe. 3. Natural hybridisation between goldfish and crucian carp occurs frequently, although hybrids between all other species pairs were observed. Only 62% of British crucian carp populations (n = 21) consisted exclusively of pure crucian carp. In some populations hybrids were so frequent, that no pure crucian carp were caught, indicating a high competitive ability of hybrids. 4. Most hybrids belonged to the F1 generation but backcrossing was evident at a low frequency in goldfish × crucian carp hybrids and goldfish × common carp hybrids. Furthermore, some local populations had high frequencies of backcrosses, raising the opportunity for introgression. 5. Gibel carp from Germany and Italy belonged to two triploid clonal lineages that were genetically closely related to goldfish, whereas all individuals identified from British populations proved to be crucian carp × goldfish hybrids. 6. Our study suggests that the release of closely related exotic cyprinids not only poses a threat to the genetic integrity and associated local adaptations of native species, but may also contribute to shifts in community structure through competitive interactions.