Trichlorfon, an organophosphorus insecticide, depresses the immune responses and resistance to Lactococcus garvieae of the giant freshwater prawn Macrobrachium rosenbergii

The total haemocyte count (THC), phenoloxidase activity, respiratory bursts (release of superoxide anions), superoxide dismutase (SOD) activity, and phagocytic activity and clearance efficiency to the pathogen Lactococcus garvieae were measured when freshwater giant prawns Macrobrachium rosenbergii (18.2+/-2.1 g) were individually reared in water containing concentrations of trichlorfon of 0, 0.2, or 0.4 mg L(-1) for a 144-h period. No significant differences in the THC were observed among prawns at the beginning and following 144 h of exposure to 0, 0.2, and 0.4 mg L(-1) trichlorfon. However, phenoloxidase activity significantly decreased when the prawns were exposed to trichlorfon at 0.2 and 0.4 mg L(-1), and no significant differences were observed between the two concentrations at any sampling time. The total production of superoxide anion by M. rosenbergii significantly increased with exposure to 0.2 and 0.4 mg L(-1) trichlorfon, and no significant differences were observed between the two concentrations during the 144-h exposure period. However, M. rosenbergii exposed to 0.2 and 0.4 mg L(-1) trichlorfon showed decreased SOD activity from 48 to 144 h. Phagocytic activity and clearance efficiency to L. garvieae significantly decreased when prawns were exposed to 0.2 and 0.4 mg L(-1) trichlorfon for 48 h. In another experiment, prawns were challenged with 5 x 10(5) colony-forming units (cfu)prawn(-1) of L. garvieae, then reared in water containing different concentrations of trichlorfon. The onset of mortality was earlier in prawns exposed to trichlorfon compared to those exposed to the zero control. The cumulative mortality of prawns directly increased with ambient trichlorfon concentrations in the range of 0-0.4 mg L(-1) after 168 h. It is concluded that exposure of M. rosenbergii to trichlorfon at 0.2 mg L(-1) or more caused cytotoxicity resulting in depression of the immune response, and increased its susceptibility to L. garvieae infection.     

Dietary sodium alginate administration affects fingerling growth and resistance to Streptococcus sp. and iridovirus, and juvenile non-specific immune responses of the orange-spotted grouper, Epinephelus coioides

The percent weight gain (PWG) and feeding efficiency (FE) of fingerling orange-spotted grouper, Epinephelus coioides, fed diets containing sodium alginate at 1.0 and 2.0 g kg(-1) were calculated on the 2nd, 4th, 6th, and 8th weeks after feeding. Survival rates of the fingerling grouper against Streptococcus sp. and an iridovirus, and non-specific immune parameters such as alternative complement activity (ACH50), lysozyme activity, natural haemagglutination activity, respiratory bursts, superoxide dismutase (SOD) activity, and phagocytic activity of juvenile grouper were also determined when the fish were fed diets containing sodium alginate at 0.5, 1.0, or 2.0 g kg(-1). The PWG and FE of fish were better when the fish were fed diets containing sodium alginate at 1.0, and 1.0 and 2.0 g kg(-1), respectively. The PWG and FE of fish fed the 0, 1.0 and 2.0 g kg(-1) sodium alginate-containing diets after 8 weeks were 271.0%, 454.4% and 327.8%, and 0.61, 0.72 and 0.68, respectively. Fish fed a diet containing sodium alginate at the level of 2.0 g kg(-1) had a significantly higher survival rate than those fed the control diet after challenge with Streptococcus sp. and an iridovirus causing an increase of survival rate by 25.0% and 16.7%, respectively, compared to the control group. The ACH(50) level of fish fed the sodium alginate-containing diets at 2.0 g kg(-1) was significantly higher than those fed the 1.0 g kg(-1) sodium alginate diet and control diet after 12 days, and had increased to 1.9-fold, compared to those fed the control diet. The lysozyme activity, phagocytic activity, respiratory bursts, and SOD level of fish fed the sodium alginate-containing diets at 1.0 and 2.0 g kg(-1) were significantly higher than those fed the control diet after 12 days, and had increased to 1.97- and 1.68-fold, 1.35- and 1.50-fold, 1.63- and 1.81-fold, and 1.23- and 1.31-fold, respectively, compared to those fed the control diet. We therefore recommend dietary sodium alginate administration at 1.0 and 2.0 g kg(-1), respectively, to promote growth and enhance immunity and resistance against Streptococcus sp. and an iridovirus.     

Effect of benzalkonium chloride stress on immune resistance and susceptibility to Lactococcus garvieae in the giant freshwater prawn Macrobrachium rosenbergii

Addition of benzalkonium chloride (BKC) at 0, 0.3, 0.6 and 1.0 mg l(-1) to tryptic soy broth (TSB) had no effect on growth of Lactococcus garvieae, a bacterial pathogen of the giant freshwater prawn Macrobrachium rosenbergii. However, injection of the cultured cells into prawns at a dose of 4 x 10(6) colony-forming units (cfu) prawn(-1) resulted in significantly higher mortality at 120 h (p < 0.05) in prawns injected with cells grown in the absence of BKC than in prawns injected with cells grown in the presence of BKC. In other experiments, prawns were injected with TSB-grown L. garvieae (4 x 10(6) and 3 x 10(5) cfu prawn(-1)) and then held in water containing BKC at 0, 0.3, 0.6 and 1.0 mg l(-1). After 120 h, mortality was significantly higher in all the BKC treatments than in the control without BKC. Prawns showed no significant differences in total hemocyte count (THC) or differential hemocyte count (DHC) amongst treatment and control groups. However, 96 h exposure to 0.3 mg l(-1) BKC or more resulted in a decrease in phenoloxidase activity and an increase in respiratory burst to levels considered to be cytoxic. In summary, exposure of L. garvieae to BKC at 0.3 mg l(-1) or more decreased its virulence to M. rosenbergii, while exposure of M. rosenbergii to BKC at 0.3 mg l(-1) or more increased its susceptibility to L. garvieae infection.     

Effects of the dietary administration of sodium alginate on the immune responses and disease resistance of Taiwan abalone,Haliotis diversicolor supertexta

Sodium alginate extracted from brown algae was reported to enhance the immune response and resistance of fish and shrimp. In this study, survival rates of the abalone, Haliotis diversicolor supertexta, against Vibrio parahaemolyticus, and its non-specific immune parameters such as the total haemocyte count (THC), phenoloxidase (PO) activity, respiratory bursts, superoxide dismutase (SOD) activity, phagocytic activity, and clearance efficiency to V. parahaemolyticus by H. diversicolor supertexta were determined when abalone (4.5 ± 0.4 g) were fed diets containing sodium alginate at 0, 1.0, 2.0, and 3.0 g kg^?1. Abalone fed a diet containing sodium alginate at 2.0 and 3.0 g kg^?1 for 14 days and at 1.0 g kg^?1 for 21 days had significantly higher survival rates than those fed the control diet after challenge with V. parahaemolyticus. The relative survival percentages of abalone fed the 1.0, 2.0, and 3.0 g kg^?1 sodium alginate-containing diets for 14 and 21 days were 16.1%, 40.0%, and 48.0%, and 63.6%, 27.3% and 22.6%, respectively. The PO activity, respiratory bursts, SOD activity, and phagocytic activity and clearance efficiency of V. parahaemolyticus of abalone fed the sodium alginate-containing diets at 1.0, 2.0, and 3.0 g kg^?1 were significantly higher than those of abalone fed the control diet for 14 days. After 21 days, the PO activity, respiratory bursts, SOD activity, and phagocytic activity and clearance efficiency of V. parahaemolyticus by abalone fed the sodium alginate-containing diet at 1.0 g kg^?1 were significantly higher than those of abalone fed the other diets. It was concluded that sodium alginate can be used as an immunostimulant for abalone through dietary administration to enhance immune responses of abalone and resistance against V. parahaemolyticus, which were related to the dose and timing of administration.     

The susceptibility of the giant freshwater prawn Macrobrachium rosenbergii to Lactococcus garvieae and its resistance under copper sulfate stress.

Addition of copper sulfate (0.1 to 0.4 mg l(-1)) to tryptic soy broth (TSB) had no effect on growth rate of the bacterial pathogen Lactococcus garvieae. Giant freshwater prawns Macrobrachium rosenbergii were injected with L. garvieae (4 x 10(6) colony-forming units [cfu] prawn(-1)) grown in TSB or TSB containing copper sulfate at 0.1, 0.2, 0.3 or 0.4 mg l(-1). After 48 h, the cumulative mortality was significantly (p < 0.05) higher for prawns exposed to L. garvieae grown in 0.4 mg l(-1) copper sulfate than at the lower concentrations examined. In other experiments, prawns were injected with TSB-grown L. garvieae (4 x 10(6) and 2 x 10(5) cfu prawn(-1)), then held in water containing copper sulfate. After 8 h the mortality of L. garvieae-exposed prawns held in water containing 0.4 mg l(-1) copper sulfate was significantly higher than prawns held in water containing 0.2 and 0.3 mg l(-1) copper sulfate. At the lower L. garvieae density, cumulative mortality of prawns increased directly with ambient copper sulfate concentrations in the range of 0.2 to 0.4 mg l(-1). All prawns survived a 168 h exposure to 0.1 mg l(-1) copper sulfate. Prawns exposed to different concentrations of copper sulfate were examined for hemocyte density, phenoloxidase activity and respiratory burst. No significant differences in hemocyte density were observed among treatments. In prawns following a 48 h exposure to 0.1 mg l(-1) copper sulfate, phenoloxidase activity was decreased, but respiratory burst was increased. In conclusion, copper sulfate increased the virulence of L. garvieae to M. rosenbergii and modulated its immune system. Copper sulfate at 0.1 mg l(-1) decreased susceptibility of M. rosenbergii to L garvieae infection, whereas at 0.2 mg l(-1) the susceptibility was increased. The generation of superoxide anion by M. rosenbergii exposed to copper sulfate at a concentration higher than 0.2 mg l(-1) was considered to be cytoxic.     

Dietary administration of sodium alginate enhances the immune ability of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

Haemocyte count, phenoloxidase activity, respiratory burst (release of superoxide anion), superoxide dismutase (SOD) activity, glutathione peroxidase (GPX) activity, phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were measured in white shrimp Litopenaeus vannamei juveniles (12.3 +/- 1.2 g) which had been fed diets containing sodium alginate at 0.5, 1.0, 2.0 g kg(-1) after five months. L. vannamei fed a diet containing 2.0 g kg(-1) sodium alginate had increased phenoloxidase activity, respiratory burst and SOD activity, but decreased GPX activity significantly. L. vannamei fed a diet containing 2.0 g kg(-1) sodium alginate had increased phagocytic activity and the shrimp fed a diet containing sodium alginate at 0.5, 1.0 or 2.0 g kg(-1) had increased clearance efficiency to V. alginolyticus. In another experiment, L. vannamei, which had been fed control diet, or sodium alginate-containing diets after 5 months, were challenged with V. alginolyticus at 2 x 10(6) colony-forming units (CFU) shrimp(-1) and then placed in seawater of 15 per thousand. The survival of shrimp fed a diet containing 2.0 g kg(-1) after one day, and the survival of shrimp fed diets containing sodium alginate at 0.5 and 1.0 g kg(-1) after 2-4 days increased significantly, as compared to that of shrimp fed control diet. It is therefore concluded that administration of sodium alginate in the diet at 2.0 g kg(-1) or less could enhance the immune ability of L. vannamei and increase its resistance to V. alginolyticus infection.     

Effect of cadmium on survival,osmoregulation and gill structure of the Sunda prawn,Macrobrachium sintangense (de Man), at different salinities

The prawn Macrobrachium sintangense is likely to be subjected to occasional exposure to combined metal and saline stressors in its natural environment. This research evaluated the acute toxicity (96?h LC₅₀) of cadmium (Cd) on the prawn M. sintangense, with respect to the osmoregulatory capacity (OC) of prawns and to document histological changes in the gills after exposure to sublethal Cd concentrations at different salinities. The 96?h LC₅₀ of Cd to M. sintangense decreased with increasing salinity. The 96?h LC₅₀ values were 89.12 (72.53–109.50), 681.26 (554.20–837.46) and 825.37 (676.99–1006.27) μg CdL^?1 at 0, 10 and 20 ppt, respectively. The OC of prawns exposed to 30?μg?CdL^?1 at 0 ppt and to 300?μg?CdL^?1 at10 ppt decreased significantly compared with that of control prawns exposed to 0 and 10 ppt respectively. Swelling, hyperplasia and necrosis of gill lamellae resulting in the loss of marginal canals were observed in the gills of prawns exposed to 30?μg?CdL^?1 at 0 ppt and to 300?μg?CdL^?1 at 10 ppt for 7?days.     

Effect of hypoxia on the immune response of giant freshwater prawn Macrobrachium rosenbergii and its susceptibility to pathogen Enterococcus

Giant freshwater prawns Macrobrachium rosenbergii (14-19 g) were challenged with Enterococcus (3 x 10(5) cfu prawn(-1)) previously incubated in TSB medium for 24 h, then placed in water having concentrations of dissolved oxygen (DO) at 7.75, 4.75, 2.75 and 1.75 mg l(-1). Onset of mortality occurred after 6 h exposure to 1.75 mg l(-1) DO, and after 12 h exposure to 2.75 mg 1(-1) DO. Cumulative mortality of prawns at 1.75 mg l(-1) DO was significantly higher than that at 4.75 and 2.75 mg l(-1) DO, and cumulative mortality of prawns at 4.75 and 2.75 mg l(-1) DO was significantly higher than that at 7.75 mg l(-1) DO after 96 h. The prawns (20-30 g) which had been placed in water for 0 to 120 h at 7.75, 4.75, 2.75 and 1.75 mg l(-1) DO were examined for the THC (total haemocyte counts), DHC (differential haemocyte counts), phenoloxidase activity, respiratory burst, percentage phagocytosis and clearance efficiency. No significant difference in semi-granular cells and granular cells of prawns was observed among four treatments. The prawns following 120 h exposure to 2.75 mg l(-1) DO decreased significantly the hyaline cells and THC by 39% and 36%, respectively. Phenoloxidase activity and respiratory burst decreased significantly by 33% and 11% when the prawns were exposed to 2.75 mg l(-1) DO after 24 h, respectively. Percentage phagocytosis and clearance efficiency to Enterococcus decreased significantly by 44% and 54% for the prawns following 12 h exposure to 2.75 mg l(-1) DO, respectively. It is concluded that DO as low as 2.75 mg l(-1) and 4.75 mg l(-1) causes depression in immune system of M. rosenbergii, and increases its susceptibility to Enterococcus infection.     

Lead toxicity at different life stages of the giant prawn (Macrobrachium rosenbergii,de Man): considerations of osmoregulatory capacity and histological changes in adult gills

This study evaluated the acute toxicity of lead in different life stages of the freshwater prawn Macrobrachium rosenbergii, determined the effect of sublethal Pb concentrations on osmoregulatory capacity (OC), measured the Pb level in gills, and investigated the effect of Pb on the structure of the gills of adult prawns. The 24-, 48-, and 96-h LC₅₀ values for Pb to M. rosenbergii increased progressively with increasing life stage, from post-larvae (PL), juvenile to adult. The 24- and 48-h LC₅₀ values for post-larvae ranged from 0.01- to 0.09-mg Pb/L. The 24-, 48-, and 96-h LC₅₀ values for Pb were lower at 12 ppt than those at 0 ppt for either the juveniles or the adults. At 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.47-, 0.58-, and 2.03-mg Pb/L, respectively. Meanwhile, at 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.63-, 4.44-, and 7.98-mg Pb/L, respectively. In adults, the OC values of controls and prawns exposed to 2- and 4-mg Pb/L at 0 ppt were not significantly different. The OC of prawns exposed to and 2-mg Pb/L at 12 ppt increased by 72 and 109% from the OC of the control prawns. At media 12 ppt, the OC value of prawns exposed to 1-mg Pb/L was significantly different from that of prawns exposed to 2-mg Pb/L. The concentrations of Pb in gill tissues increased significantly in Pb exposed prawns both at 0 and 12 ppt. The level of Pb in gills of prawns exposed to 2-mg Pb/L at 12 ppt was not significantly different from those exposed at 0 ppt. The severe toxic actions of Pb were noted in gills of prawns exposed in media 12 ppt. Hyperplasia and necrosis were observed in gill lamellae, resulting in abnormal gill tips after Pb exposure at media 12 ppt. Since the effect of Pb is more pronounced in higher salinity (12 ppt) than in freshwater (0 ppt) it is clear that aquaculture of M. rosenbergii should be conducted in freshwater ponds.     

Tank-Mix compatibility of the entomopathogenic nematodes, Heterorhabditis bacteriophora and Steinernema carpocapsae, with selected chemical pesticides used in turfgrass

We evaluated the compatibility of two entomopathogenic nematodes, Heterorhabditis bacteriophora HP88 and Steinernema carpocapsae All strain with selected pesticide formulations used in turfgrass in tank-mixes under laboratory conditions. The nematodes were exposed to the recommended rates of pesticides applied in either 100, 300, or 500 L/ha tank-mix volumes in 24-well plates at room temperature for 3 h and infective juveniles (IJ) viability determined, and then tested against Galleria mellonella larvae at 22-26°C for 96 h to assess IJ pathogenicity. We found that S. carpocapsae viability was not affected by any of the pesticides, while aluminum tris and trichlorfon significantly reduced S. carpocapsae pathogenicity at all concentrations. Thiamethoxam and trichlorfon significantly reduced H. bacteriophora viability, while halofenozide, aluminum tris, trichlorfon, and carbaryl significantly reduced H. bacteriophora pathogenicity. Imidacloprid, at the recommended rate 330-440 g AI/ha, significantly increased H. bacteriophora pathogenicity at 500 and 300 L/ha application volume. The integration of these nematode pesticide combinations in turf pest management programs is discussed.     

Effect of potassium permanganate stress on immune resistance and susceptibility to Lactococcus garvieae in the giant freshwater prawn Macrobrachium rosenbergii

This work is part of a continuing series of investigations on the effect of commonly used aquaculture chemicals on the immune resistance and susceptibility of the giant freshwater prawn Macrobrachium rosenbergii to Lactococcus garvieae. The methodology has been described in earlier publications of the series. Potassium permanganate at 1.0 mg l(-1) in tryptic soy broth (TSB) had no effect on the growth rate of L. garvieae. The mortality of M. rosenbergii challenged with 4 x 10(6) colony-forming units (cfu) prawn(-1) of TSB-grown L. garvieae was significantly greater than that of challenged controls. Addition of potassium permanganate at 1.0 mg l(-1) in TSB significantly increased the virulence of L. garvieae to M. rosenbergii. Exposure of M. rosenbergii to potassium permanganate prior to challenge with TSB-grown L. garvieae at 4 x 10(6) and 3 x 10(6) cfu prawn(-1) revealed that 96 h mortality was significantly lower for prawns held in water containing 0.3 mg l(-1) of the chemical than for prawns in water containing 1.0 mg l(-1) or no chemical. Potassium permanganate caused no significant changes in total hemocyte counts and differential hemocyte counts, compared to the control treatments. However, a concentration of 1.0 mg l(-1) or more for 96 h resulted in decreased phenoloxidase activity, phagocytic activity and clearance efficiency. Respiratory burst increased with exposure to 0.3 mg l(-1). In conclusion, treatment with potassium permanganate at 0.3 mg 1(-1) was effective in reducing M. rosenbergii mortality from L. garvieae infection, but higher concentrations had a negative effect, probably due to reduced prawn defenses.     

Effect of exposure to cadmium on the tropical freshwater prawn Macrobrachium rosenbergii

The effect of cadmium (Cd) on mortality, resistance and bioaccumulation in the tropical freshwater prawn Macrobrachium rosenbergii from Egypt were studied. Survival of prawns exposed to Cd doses over 60 μg l^?1 were significantly lower than that of prawns exposed to lower doses. After 96 h prawns exposed to >40 μg l^?1 of Cd had a greater reduction in total haemocyte count and phagocytic activity than those exposed to lower concentrations. Bioaccumulation of Cd in the gills, hepatopancreas and muscles was variable. Cadmium accumulated significantly in the gills and hepatopancreas, but Cd accumulation in the muscles increased only marginally. Macrobrachium rosenbergii manifested histopathological alterations in the gills, hepatopancreas and muscles when exposed to various concentrations of cadmium.     

Effects of intrinsic and extrinsic factors on the haemocyte profile of the prawn, Macrobrachium rosenbergii

The giant freshwater prawn Macrobrachium rosenbergii was investigated for its total haemocyte count (THC) based on season, sex, size and feeding rate. The THC, when the prawns were subjected to injections of foreign materials was also investigated. The prawns displayed the highest and lowest THC in autumn and winter respectively, with no significant difference between male and female, or among animals with a body weight range of 7-115 g. The prawns displayed the lowest THC at D3 stage, and the highest in C stage. The prawns displayed the lowest THC when they were fed at 0.1% feeding rate among feeding rates of 0.1%, 0.5%, 1.0% and 1.5% body weight x day(-1). Prawns injected with carbon powder and Enterococcus showed increased THC during the first 6 h. Prawns injected with saline and carbon powder had the lowest THC after 30 h, and recovered to the normal value after 54 h. Prawns injected with Enterococcus showed the lowest THC after 42 h, and showed delayed recovery.     

Dietary copper requirement of juvenile grass shrimp,Penaeus monodon,and effects on non-specific immune responses

An 8-week feeding trial was conducted to determine the dietary copper (Cu) requirement and its effect on the non-specific immune responses of juvenile grass shrimp, Penaeus monodon. Purified diets with seven levels (0, 10, 20, 30, 40, 80, 160 mg Cu kg diet(-1) of supplemental Cu were fed to P. monodon (mean initial weight 0.29 +/- 0.004 g). Each diet was fed to three replicate groups of shrimp. The rearing water contained 1.53 microg Cu 1(-1). Shrimp fed diets supplemented with 10 and 20 mg Cu kg diet(-1) had significantly (P < 0.01) greater weight gain, feed efficiency (FE) and protein efficiency ratio (PER) than those fed the unsupplemented control diet and diets supplemented with > or = 40 mg Cu kg diet(-1). Whole body Cu concentration in shrimp generally increased as dietary Cu supplementation increased. Total haemocyte count (THC) was higher in shrimp fed diets supplemented with 10-30 mg Cu kg diet(-1) than shrimp fed the unsupplemented control diet and diets supplemented with > or = 40 mg Cu kg diet(-1). Intracellular superoxide anion (O2-) production ratios were significantly higher in shrimp fed diets supplemented with 10-30 mg Cu kg diet(-1) than shrimp fed the diet supplemented with 160 mg Cu kg diet(-1). Analysis by polynomial regression of weight gain percent, FE and by linear regression of the whole-body Cu retention of shrimp indicated that the adequate dietary Cu concentration in growing P. monodon is about 15-21 mg Cu kg diet (-1). The immune indicators suggest that an adequate dietary Cu concentration for non-specific immune responses in P. monodon is about 10-30 mg Cu kg diet(-1).     

Use of a novel genetic mouse model to investigate the role of folate in colitis-associated colon cancer

Inflammatory bowel disease (IBD) patients are at high risk for developing folate deficiency and colon cancer. Since it is difficult to study the subtle global and gene-specific epigenetic mechanisms involved in folate-mediated tumor initiation and promotion, we have generated genetically modified mouse models by targeting the reduced folate carrier (RFC1) and folate-binding protein (Folbp1) genes. The transgenic mice were fed semi-purified diets for 8 weeks containing either normal (2 mg) or deficient (0.1 mg folate/kg diet) levels of folate. Compound heterozygous mice (Folbp1(+/-); RFC1(+/-)) fed an adequate folate diet exhibited a reduction in plasma folate concentrations compared to heterozygous (Folbp1(+/-)) and littermate wild-type mice (P<.05). In contrast, no differences were observed in colonic mucosa. Consumption of a low folate diet significantly reduced (three- to fourfold) plasma and tissue folate levels in all animal models, although plasma homocysteine levels were not altered. In order to elucidate the relationship between folate status and inflammation-associated colon cancer, animals were injected with azoxymethane followed by dextran sodium sulphate treatment in the drinking water. Mice were fed a normal folate diet and were terminated 5 weeks after carcinogen injection. The number of high multiplicity aberrant crypt foci per centimeter of colon was significantly elevated (P<.05) in compound Folbp1(+/-); RFC1(+/-) (3.5+/-0.4) mice as compared to Folbp1(+/-) (1.9+/-0.3) and wild-type control mice (1.1+/-0.1). These data demonstrate that the ablation of two receptor/carrier-mediated pathways for folate transport increases the risk for developing inflammation-associated colon cancer.     

Effects of dietary chitosan and Bacillus subtilis on the growth performance, non-specific immunity and disease resistance of cobia, Rachycentron canadum

The present study was performed to investigate the effects of various levels of dietary Bacillus subtilis and chitosan on the growth performance, non-specific immunity and protection against Vibrio harveyi infection in cobia, Rachycentron canadum. Fish were fed with the control diet and six different experimental diets containing three graded levels of B. subtilis at 2 × 10(10) CFU g(-1) (0.0, 1.0, 2.0 g kg(-1) diet) for each of two levels of chitosan (3.0 and 6.0 g kg(-1) diet). The results of 8 weeks feeding trial showed that the survival rate ranged from 81.3% to 84.0% with no significant difference (P > 0.05). The SGR (%) in the fish fed with dietary treatments was significantly higher than that of the control fish except diet 6 group with 2.0 g kg(-1)B. subtilis and 3.0 g kg(-1) chitosan. The serum lysozyme activities were significantly higher in 6.0 g kg(-1) chitosan groups and no significant differences were observed among B. subtilis levels. The serum ACP activities were significantly higher in 3.0 g kg(-1) chitosan groups at 0.0 and 1.0 g kg(-1)B. subtilis levels; at low chitosan level, the cobia fed diets with 1.0 g kg(-1)B. subtilis had significantly higher serum ACP activity, but at high chitosan level, the cobia fed diets with 2.0 g kg(-1)B. subtilis had significantly higher serum ACP activity. The phagocytosis and respiratory burst activity in the fish fed with dietary treatments was significantly higher than that of the control fish except diet 3 group with 6.0 g kg(-1) chitosan. Moreover, fish fed the diet containing 2.0 g kg(-1)B. subtilis and 6.0 g kg(-1) chitosan had significantly higher post-challenge survival on the 7th day following V. harveyi infection and post-challenge survival showed clearly the synergistic effect of chitosan and B. subtilis. Based on these results, the combination of 1.0 g kg(-1)B. subtilis and 6.0 g kg(-1) chitosan is optimal for the growth, innate immunity and disease resistance of cobia with an 8-week oral administration.     

Copper transporter 1, metallothionein and glutathione reductase genes are differentially expressed in tissues of sea bream (Sparus aurata) after exposure to dietary or waterborne copper

The high affinity copper transporter 1 (Ctr1), metallothionein (MT) and glutathione reductase (GR) are essential for copper uptake, sequestration and defense respectively. Following rearing on a normal commercial diet (12.6+/-0.2 mg kg(-1) Cu), sea bream were fed an experimental control diet lacking mineral mix (7.7+/-0.3 mg kg(-1) Cu), an experimental diet enhanced with Cu (135+/-4 mg kg(-1) Cu) or an experimental diet (7.7+/-0.3 mg kg(-1) Cu) whilst exposed to Cu in water (0.294+/-0.013 mg L(-1)). Fish were sampled at 0, 15 and 30 days after exposures. Fish fed the Cu-enhanced experimental diet showed lower levels of expression of Ctr1 in the intestine and liver compared to fish fed control experimental diets, whilst Ctr1 expression in the gill and kidney was unaffected by excess dietary Cu exposure. Waterborne-Cu exposure increased Ctr1 mRNA levels in the intestine and the kidney compared to experimental controls. Excess dietary Cu exposure had no effect on levels of metallothionein (MT) mRNA, and the only effect of dietary excess Cu on glutathione reductase (GR) mRNA was a decrease in the intestine. Both MT mRNA and GR were increased in the liver and gill after waterborne-Cu exposure, compared to levels in fish fed experimental control low Cu diets. Thus, Ctr1, MT and GR mRNA expression in response to excess Cu is dependent on the route of exposure. Furthermore, the tissue expression profile of sea bream Ctr1 is consistent with the known physiology of copper exposure in fish and indicates a role both in essential copper uptake and in avoidance of excess dietary and waterborne copper influx.