Administration of hot-water extract of brown seaweed Sargassum duplicatum via immersion and injection enhances the immune resistance of white shrimp Litopenaeus vannamei

The total haemocyte count (THC), phenoloxidase activity, and respiratory burst were examined when the white shrimp Litopenaeus vannamei (10.42+/-1.39 g) were immersed in seawater (34 per thousand) containing hot-water extract of brown alga Sargassum duplicatum at 100, 300 and 500 mg l(-1), or injected with hot-water extract of S. duplicatum at 2, 6, 10 and 20 microg g(-1). These parameters increased significantly when the shrimp were immersed in seawater containing hot-water extract at 300 and 500 mg l(-1) after 1 h, or when the shrimp were injected with hot-water extract at 10 and 20 microg g(-1) after 1 day. L. vannamei that were injected with hot-water extract at 6, 10 and 20 microg g(-1) had increased phagocytic activity and clearance efficiency to V. alginolyticus after 1-6 days. In another experiment, L. vannamei which had been immersed in seawater containing hot-water extract at 100, 300 and 500 mg l(-1), or injected with hot-water extract at 2, 6, 10 or 20 microg g(-1) were challenged with V. alginolyticus at 1 x 10(6), or 1.4 x 10(6) colony-forming units (cfu) shrimp(-1), and then placed in seawater. The survival of shrimp that received hot-water extract at either dose was significantly higher than that of control shrimp after 2 days, as well as at the termination of the experiment (6 days after the challenge). It is therefore concluded that L. vannamei that were immersed in hot-water extract of S. duplicatum at 300 mg l(-1), or the shrimp that were injected with hot-water extract at 10 microg g(-1) or less had increased immune ability as well as resistance to V. alginolyticus infection.     

Dietary administration of a Gracilaria tenuistipitata extract enhances the immune response and resistance against Vibrio alginolyticus and white spot syndrome virus in the white shrimp Litopenaeus vannamei

The haemogram, phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, lysozyme activity, and the mitotic index of haematopoietic tissue (HPT) were examined after the white shrimp Litopenaeus vannamei had been fed diets containing the hot-water extract of Gracilaria tenuistipitata at 0 (control), 0.5, 1.0, and 2.0 g kg(-1) for 7-35 days. Results indicated that these parameters directly increased with the amount of extract and time, but slightly decreased after 35 days. RBs, SOD activity, and GPx activity reached the highest levels after 14 days, whereas PO and lysozyme activities reached the highest levels after 28 days. In a separate experiment, white shrimp L. vannamei, which had been fed diets containing the extract for 14 days, were challenged with Vibrio alginolyticus at 2 × 10(6) cfu shrimp(-1) and white spot syndrome virus (WSSV) at 1 × 10(3) copies shrimp(-1), and then placed in seawater. The survival rate of shrimp fed the extract-containing diets was significantly higher than that of shrimp fed the control diet at 72-144 h post-challenge. We concluded that dietary administration of the G. tenuistipitata extract at ≤1.0 g kg(-1) could enhance the innate immunity within 14 days as evidenced by the increases in immune parameters and mitotic index of HPT in shrimp and their enhanced resistance against V. alginolyticus and WSSV infections. Shrimp fed the extract-containing diets showed a higher and continuous increase in the humoral response indicating its persistent role in innate immunity.     

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.     

The immunostimulatory effect of hot-water extract of Gracilaria tenuistipitata on the white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

The total haemocyte count (THC), phenoloxidase activity, respiratory burst, superoxide dismutase (SOD) activity, phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were examined in the white shrimp Litopenaeus vannamei (10.3+/-1.5 g) injected individually with hot-water extract of Gracilaria tenuistipitata at 4 or 6 microg g-1. L. vannamei receiving hot-water extract of G. tenuistipitata at either dose increased significantly its THC, phenoloxidase activity, and respiratory burst after 2 days. L. vannamei received hot-water extract of G. tenuistipitata at 6 microg g-1 increased its phagocytic activity and clearance efficiency to V. alginolyticus after 1 day. In another experiment, L. vannamei which had been injected with hot-water extract of G. tenuistipitata were challenged with V. alginolyticus at 2x10(6) colony-forming units (cfu) shrimp-1 and then placed in seawater of 34 per thousand. The survival of shrimp that received hot-water extract of G. tenuistipitata at 6 microg g-1 was significantly higher than that of shrimp that received saline and the control shrimp after 3 days, and at the termination of the experiment (6 days after the challenge). It is therefore concluded that L. vannamei receiving the hot-water extract of G. tenuistipitata at 6 microg g-1 or less increased its immune ability and resistance to V. alginolyticus 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.     

The protective effect of chitin and chitosan against Vibrio alginolyticus in white shrimp Litopenaeus vannamei

White shrimp, Litopenaeus vannamei, which had been injected with chitin at 4, 6 and 8 microg g(-1) or chitosan at 2, 4 and 6 microg g(-1), were challenged with pathogen Vibrio alginolyticus at 2 x 10(6) colony-forming units (cfu) shrimp(-1) and then placed in seawater of 34 per thousand. The survival of shrimp that received chitin or chitosan at either dose was significantly higher than that of control shrimp after 1 day, and at the termination of the experiment (6 days after the challenge). In another experiment, the total haemocyte count (THC), phenoloxidase activity, respiratory burst, superoxide dismutase (SOD) activity, and phagocytic activity to V. alginolyticus were measured when L. vannamei (10.4 +/- 0.7 g) were injected individually with chitin at 4 and 6 microg g(-1) or chitosan at 2 and 4 microg g(-1). L. vannamei received chitin at 6 microg g(-1) or chitosan at 2 and 4 microg g(-1) increased significantly its THC and respiratory burst after 2 days. L. vannamei received chitin at 6 microg g(-1) or chitosan at 2 and 4 microg g(-1) still maintained significantly higher phenoloxidase activity after 6 days. L. vannamei received chitin at 4 and 6 microg g(-1) or chitosan at 2 and 4 microg g(-1) increased its phagocytic activity against V. alginolyticus after 1 day, respectively. It is therefore concluded that L. vannamei that received chitin at 6 microg g(-1) or chitosan at 4 microg g(-1) or less increased its immune ability and resistance to V. alginolyticus infection.     

Effects of dietary mannan oligosaccharide on growth performance, gut morphology and stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei

An 8-week feeding trial was conducted to investigate the effects of dietary mannan oligosaccharide (MOS) on growth performance, gut morphology, and NH(3) stress tolerance of Pacific white shrimp Litopenaeus vannamei. Juvenile Pacific white shrimp (1080 individuals with initial weight of 2.52?±?0.01?g) were fed either control diet without MOS or one of five dietary MOS (1.0, 2.0, 4.0, 6.0 and 8.0?g?kg(-1)) diets. After the 8-week feeding trial, growth parameters, immune parameters, intestinal microvilli length and resistance against NH(3) stress were assessed. Weight gain (WG) and specific growth rate (SGR) were significantly higher (P??0.05) in all experimental groups. Compared with control group, TEM analysis revealed that 2.0, 4.0, 6.0 and 8.0?g?kg(-1) MOS supplementation could significantly increase (P?相似文献   

The immune stimulatory effect of sodium alginate on the white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

The total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase activity, respiratory burst (release of superoxide anion), superoxide dismutase activity, phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were measured when the white shrimp Litopenaeus vannamei (9.4-11.3 g) were injected individually with sodium alginate at 10, 20 or 50 microg g(-1). No significant differences in THC, DHC and superoxide dismutase activity were observed among the shrimp injected with saline and those injected with sodium alginate at 10, 20 or 50 microg g(-1). However, L. vannamei injected with sodium alginate at 20 microg g(-1)increased its phenoloxidase activity and respiratory burst after 2 days and one day, respectively. L. vannamei injected with sodium alginate at 50 microg g(-1)maintained a higher phagocytic activity and clearance efficiency to V. alginolyticus after 4 days. In another experiment, L. vannamei which had been injected with sodium alginate, were challenged with V. alginolyticus at 2x10(5)colony-forming units (CFU) shrimp(-1)and then placed in seawater of 34 per thousand. The survival of shrimp that received sodium alginate at either dose was significantly higher than that of control shrimp at the termination of the experiment (6 days after the challenge). It is therefore concluded that L. vannamei received sodium alginate at 10 microg g(-1)or more and increased its immune ability and resistance from V. alginolyticus infection.     

White shrimp Litopenaeus vannamei immersed in seawater containing Sargassum hemiphyllum var. chinense powder and its extract showed increased immunity and resistance against Vibrio alginolyticus and white spot syndrome virus

This study was to examine the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus and WSSV when shrimp received the Sargassum hemiphyllum var. chinense powder and its hot-water extract. Both powder and extract showed activation of prophenoloxidase and generation of superoxide anion in the shrimp in vitro. The haemocyte count, phenoloxidase (PO) activity, respiratory burst, and lysozyme activity were examined after the shrimp were immersed in seawater containing S. hemiphyllum var. chinense powder or its extract at 0, 100, 300, and 500 mg L?1 for 1, 3, and 5 h. These immune parameters of shrimp immersed in 300 and 500 mg L?1 powder, and 100 and 300 mg L?1 extract were significantly higher than those of control shrimp after 3 h, but slightly decreased after 5 h. In another experiment, shrimp immersed in seawater containing the powder or the extract at 0, 100, 300, and 500 mg L?1 after 3 h were challenged with V. alginolyticus at 8 × 10? colony-forming unit (cfu) shrimp?1, or challenged with WSSV at 1 × 10? copies shrimp?1, and then placed in seawater. Survival rate of shrimp immersed in 500 mg L?1 powder was significantly higher than that of control shrimp after 24-120 h in the V. alginolyticus-challenge test, and after 72 h in the WSSV-challenge test, respectively. Survival rate of shrimp immersed in 300 mg L?1 extract was significantly higher than that of control shrimp after 72-120 h in both V. alginolyticus-challenge and WSSV-challenge tests. It was concluded that the shrimp immersed in seawater containing the powder at 500 mg L?1, and the extract at 300 mg L?1 had increased immunity and resistance against V. alginolyticus infection, and the shrimp that received extract at 300 mg L?1 showed resistance against WSSV infection.     

Effect of saponin immersion on enhancement of the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

The haemocyte count, phenoloxidase (PO) activity, specific alpha(2)-macroglobulin (alpha2-M) activity, respiratory burst, superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, phagocytic activity, and clearance efficiency against Vibrio alginolyticus were examined when the white shrimp Litopenaeus vannamei (10.42+/-2.0g) were immersed in seawater (34 per thousand) containing different concentrations of saponin (0, 0.5, 1 and 2mgL(-1)) for 24, 48 and 72h. Hyaline cells (HC), the total haemocyte count (THC), specific alpha2-M activity, respiratory burst, SOD activity, and GPx activity directly increased with the saponin concentration, whereas PO activity was inversely related to the saponin concentration. White shrimp L. vannamei that were immersed in saponin at 1 and 2mgL(-1) showed increased phagocytic activity and clearance efficiency to V. alginolyticus over 48-72h. In another experiment, shrimp immersed in seawater containing different concentrations of saponin after 72h were challenged with V. alginolyticus at 3.2x10(5) colony-forming units (cfu)shrimp(-1), and then placed in seawater. The survival rate of shrimp immersed in seawater containing saponin at either dose was significantly higher than that of control shrimp after 12h, as well as at the termination of the experiment (5days after the challenge). It was therefore concluded that L. vannamei immersed in water containing saponin at 2mgL(-1) or less exhibited an immunomodulatory effect, as well as protection against V. alginolyticus infection.     

The effect of Sargassum fusiforme polysaccharide extracts on vibriosis resistance and immune activity of the shrimp, Fenneropenaeus chinensis

Immunostimulants are valuable for control of shrimp diseases and the immunostimulatory effects of some polysaccharide additives for shrimp have been reported. In this study, the Sargassum fusiforme polysaccharide extract (SFPSE) was assessed as a feed additive when supplemented in the diet (0%, 0.5%, 1.0%, and 2.0%) for juvenile shrimp, Fenneropenaeus chinensis, in order to study the effects of SFPSE on vibriosis resistance and immune activity. Shrimp were cultured in the same pond with cages. The body weight, survival, the cumulative mortality after injection with Vibrio harveyi (30 microl V. harveyi suspension at 9.3 x 10(7) CFU ml(-1) per shrimp), the total haemocyte counts (THCs), the protein concentration and the phenoloxidase (PO) activity in supernatant of haemolymph, the lysozyme (LSZ) and superoxide dismutase (SOD) activity in muscle of the shrimp were assayed after 14 days feeding period. The results indicated that shrimp survival under the stress of V. harveyi was affected by the dietary SFPSE. The shrimp treated with 1.0% and 0.5% SFPSE displayed significantly lower cumulative mortalities after being injected with V. harveyi suspension 24 and 30 h later, respectively, compared with that of the control. However, cumulative mortality of 2.0% SFPSE treatment was not significantly different from that of the control. There was no significant difference of cumulative mortality between 0.5% and 1.0% SFPSE treatment groups. The immune activities of the shrimp also were affected by dosage of dietary SFPSE. The THCs of the shrimp rose with increasing SFPSE dosage. The protein concentration and PO activity in supernatant of haemolymph as well as muscular LSZ activity first rose then dropped with increasing SFPSE dosage. The protein concentration in supernatant of haemolymph appeared a maximum of 167.46 mg ml(-1) in 1.0% SFPSE treatment. The PO activity and LSZ activity reached the peaks as 13.20 U and 3.21 U mgprot(-1) in 0.5% SFPSE treatment, respectively. SOD activity of the shrimp was not significantly affected by dietary SFPSE. It is therefore suggested that oral administration of SFPSE at an optimal level of 0.5% and 1.0% for 14 days effectively improved vibriosis resistance and enhanced immune activity of the shrimp in general.     

Effect of copper sulfate on the immune response and susceptibility to Vibrio alginolyticus in the white shrimp Litopenaeus vannamei

White shrimp Litopenaeus vannamei (Boone) held in 35 per thousand seawater were challenged with Vibrio alginolyticus at a dose of 3 x 10(5) colony-forming units (cfu) shrimp(-1), and then placed in water containing concentrations of Cu2+ at 0 (control), 1, 5, 10 and 20 mg l(-1). Mortality of shrimp in 5, 10 and 20 mg l(-1) Cu2+ was significantly higher than those in 1 mg l(-1) Cu2+ and the control solution after 24-96 h. In another experiment, L. vannamei which had been exposed to control, 1, 5, 10 and 20 mg l(-1) Cu2+ for 24, 48 and 96 h were examined for THC (total haemocyte count), phenoloxidase activity, respiratory burst (release of superoxide anion), phagocytic activity and clearance efficiency to V. alginolyticus. Copper concentrations at 1 mg l(-1) or greater for 24h resulted in decreased THC, phenoloxidase activity, phagocytic activity and clearance efficiency, whereas copper concentration at 20 mg l(-1) caused significant increase in respiratory burst of L. vannamei. In conclusion, concentration of Cu2+ at 1 mg l(-1) or greater increased the susceptibility of L. vannamei to V. alginolyticus infection by a depression in immune ability. The release of superoxide anion by L. vannamei exposed to 20 mg l(-1) Cu2+ was considered to be cytotoxic to the host.     

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.     

Administration of the hot-water extract of Spirulina platensis enhanced the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

White shrimp Litopenaeus vannamei which had been injected with the hot-water extract of Spirulina platensis at 6, 10, and 20 μg g^?1, or immersed in aerated seawater containing extract at 200, 400, and 600 mg L^?1 were challenged with Vibrio alginolyticus at 1.5 × 10⁶ or 1.4 × 10⁶ colony-forming units (cfu) shrimp^?1, and then placed in seawater. Survival rates of shrimp that received the extract of S. platensis at 6–20 μg g^?1, and those of shrimp immersed in seawater containing the extract at 400 and 600 mg L^?1 were significantly higher than those of control shrimp after 24–96 and 48–96 h, respectively. In a separate experiment, the hyaline cell (HC) count, granular cell (GC, including semi-granular cell) count, total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, and lysozyme activity were measured when shrimp were injected with the extract at 6, 10, and 20 μg g^?1, and immersed in seawater containing the extract at 200, 400, and 600 mg L^?1. These parameters directly increased with the concentration, and significantly increased when shrimp were immersed in the seawater containing the extract at 0.5–4 h. L. vannamei that received all doses of the extract via injection or via immersion all had increased phagocytic activity and clearance efficiency to V. alginolyticus at 12–72 h and 3–4 h, respectively. It was concluded that L. vannamei that received the hot-water extract of S. platensis had enhanced innate immunity and increased resistance against V. alginolyticus infection.     

An immersion of Gracilaria tenuistipitata extract improves the immunity and survival of white shrimp Litopenaeus vannamei challenged with white spot syndrome virus

The innate immunity and resistance against white spot syndrome virus (WSSV) in white shrimp Litopenaeus vannamei which received the Gracilaria tenuistipitata extract were examined. Shrimp immersed in seawater containing the extract at 0 (control), 400 and 600 mg L(-1) for 3 h were challenged with WSSV at 2 × 10(4) copies shrimp(-1). Shrimp not exposed to the extract and not received WSSV challenge served as unchallenged control. The survival rate of shrimp immersed in 400 mg L(-1) or 600 mg L(-1) extract was significantly higher than that of challenged control shrimp over 24-120 h. The haemocyte count, phenoloxidase activity, respiratory burst, superoxide dismutase activity, and lysozyme activity of shrimp immersed in 600 mg L(-1) extract were significantly higher than those of unchallenged control shrimp at 6, 6, 6, 6, and 6-24 h post-challenge. In another experiment, shrimp which had received 3 h immersion of 0, 400, 600 mg L(-1) extract were challenged with WSSV. The shrimp were then received a booster (3 h immersion in the same dose of the extract), and the immune parameters were examined at 12-120 h post-challenge. The immune parameters of shrimp immersed in 600 mg L(-1) extract, and then received a booster at 9, 21, and 45 h were significantly higher than those of unchallenged control shrimp at 12-48 h post-challenge. In conclusion, shrimp which had received the extract exhibited protection against WSSV as evidenced by the higher survival rate and higher values of immune parameters. Shrimp which had received the extract and infected by WSSV showed improved immunity when they received a booster at 9, 21, and 45 h post-WSSV challenge. The extract treatment caused less decrease in PO activity, and showed better performance of lysozyme activity and antioxidant response in WSSV-infected shrimp.     

Generation of superoxide anion and SOD activity in haemocytes and muscle of American white shrimp (Litopenaeus vannamei) as a response to beta-glucan and sulphated polysaccharide

Juvenile American white shrimp (Litopenaeus vannamei) were immersed in aerated beta-glucan and sulphated polysaccharide solutions for 1, 3 and 6 h. Superoxide anion and SOD activity in haemocytes and muscle were investigated to evaluate whether beta-glucan and sulphated polysaccharide induce any immunostimulatory activity. Haemocytes and muscle showed different levels of superoxide anion generation and SOD activity (2.0 and 14 times that of control, respectively) when shrimp were immersed for 6 h in aerated sea water containing beta-glucan and sulphated polysaccharide. Total haemocyte count (THC) decreased within the first 24 h after challenge with immunostimulants, but THC and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulphated polysaccharide is capable of generating an increase in the respiratory burst of L. vannamei haemocytes.     

绿原酸对凡纳滨对虾抗氧化系统及抗低盐度胁迫的影响

对绿原酸调节凡纳滨对虾(Litopenaeus vannamei)血淋巴抗氧化系统功能及抗低盐度胁迫的效果进行了评价。360尾凡纳滨对虾随机分为4组,分别投喂含有0、100、200和400 mg/kg绿原酸的饲料28 d,随后将对虾从盐度为32的天然海水直接转入至盐度为10的水中胁迫72 h。结果表明,在正常养殖条件下,绿原酸对凡纳滨对虾的成活率、血淋巴总抗氧化能力(Total antioxidative capacity, T-AOC)、超氧化物歧化酶(Superoxide dismutase, SOD)及过氧化氢酶(Catalase, CAT)活力均无明显影响,然而投喂含有绿原酸的饲料14 d,对虾血淋巴谷胱甘肽过氧化物酶(Glutathione peroxidase, GPx)活性和血淋巴细胞GPx和CAT基因表达水平均显著高于对照组(P<0.05);低盐度胁迫24 h,绿原酸组凡纳滨对虾的存活率较对照组提高10%,但各组之间无显著性差异(P>0.05);低盐度胁迫24 h,各组凡纳滨对虾血淋巴T-AOC、SOD和GPx活性与胁迫前相比均显著增加,说明低盐度胁迫条件下机体产生了抗氧化胁迫反应,同时绿原酸组对虾血淋巴GPx、CAT活性均显著高于对照组(P<0.05);低盐度胁迫72 h,绿原酸组对虾血淋巴T-AOC、GPx和CAT活性和血淋巴细胞GPx和CAT基因表达水平均明显高于对照组。上述结果表明绿原酸可有效调节凡纳滨对虾的抗氧化系统功能,增强对虾对于低盐度胁迫下的适应能力。     

White shrimp Litopenaeus vannamei that received the hot-water extract of Gracilaria tenuistipitata showed earlier recovery in immunity after a Vibrio alginolyticus injection

White shrimp Litopenaeus vannamei which had been immersed in seawater containing the hot-water extract of Gracilaria tenuistipitata at 0 (control), 200, 400, and 600 mg L^?1 for 3 h, were challenged with Vibrio alginolyticus at 4.6 × 10⁶ colony-forming units (CFU) shrimp^?1 and then placed in normal seawater (34‰). The survival rates of shrimp immersed in 200, 400, and 600 mg L^?1 of the hot-water extract were significantly higher than those of control shrimp over 48–120 h. In another experiment, L. vannamei which had been immersed in the hot-water extract at 0, 200, 400, and 600 mg L^?1 for 3 h, were challenged with V. alginolyticus at 4.0 × 10⁶ CFU shrimp^?1, and the immune parameters examined included the haemocyte count, phenoloxidase (PO) activity, respiratory burst (RB), and superoxide dismutase (SOD) activity at 12–120 h post-challenge after shrimp had been released into normal seawater. Shrimp not exposed to the hot-water extract or V. alginolyticus served as the background control. Results indicated that the haemocyte count, PO activity, RB, and SOD activity of shrimp immersed in 600 mg L^?1 were significantly higher than those of control shrimp at 12–72 h post-challenge. Results also indicated that total haemocyte count (THC), PO activity, RB and SOD activity of shrimp immersed in 400 and 600 mg L^?1 of the hot-water extract returned to the background values at 96, 48, 48, and 72 h, whereas these parameters of control shrimp returned to the original values at >120, >120, 96, and 96 h post-challenge, respectively. It was therefore concluded that L. vannamei that had been immersed in seawater containing the hot-water extract of G. tenuistipitata exhibited protection against V. alginolyticus as evidenced by the earlier recovery of immune parameters.