Immune Enzyme Activities Research Articles

Effect of pH on temperature controlled degradation of reactive oxygen species, heat shock protein expression, and mucosal immunity in the sea cucumber Isostichopus badionotus

This study evaluated the effect of pH on the activity of antioxidant and immune enzymes in the sea cucumber Isostichopus badionotus exposed to different temperatures. The organisms (530 ±110 g) were exposed to 16, 20, 24, 28, 30, 34 and 36°C for 6 h to evaluate thermal limits at two water pH values (treatment = 7.70; control = 8.17). For the thermal tolerance experiment, the organisms were exposed to sublethal temperature of 34°C for 3, 6, 12, 24, and 48 h. I. badionotus showed signs of thermal stress by synthesizing heat shock protein 70 (hsp70) at the cold (16°C) and warm thermal limits (34°C). The glutathione peroxidase (GPx) showed a negative correlation with superoxide dismutase (SOD) activity in modulating the effect of oxidative stress at different temperature levels. Specifically, GPx activity was maximal at the extremes of the cold and warm temperatures (16, 20, and 36°C) tested, while contrarily, the SOD activity increased significantly in the narrow range of temperature between 28 and 30°C, as a part of a reaction to offset oxidative damage. The effect of pH on the expression of hsp70 was not significant, whereas the antioxidant enzymes activity was stimulated at pH 7.70. Mucosal immunity, evidenced by the activation of the phenoloxidase (PO) system, increased above the basal level at pH 7.70 and at 28, 30, and 34°C. Independent of pH, the temperature of 34°C was identified as the 12 h-sublethal upper limit for I. badionotus.

Physiological and biochemical responses of Zhikong scallop,Chlamys farreri, to different thermal stressors

Water temperature is a significant environmental stressor that affects physiology and biochemical activities of bivalves. Here, temporal variations in physiological and biochemical parameters of Zhikong scallop, Chlamys farreri, under three water temperature treatments were investigated. For the first treatment, scallops were transferred from rearing temperature (15°C, control temperature) to 5, 10, 20 and 25°C, respectively. The second group of scallops was gradually acclimated to above experimental temperatures at a rate of 1–2°C day−1. The third group was transferred directly between 15 and 7°C every 12 h and for six times. Results showed that significantly higher oxygen consumption and ammonia-N excretion together with a significant lower ingestion rate was observed for the acute temperature change treatment compared to those in the equivalent gradual temperature variation treatment (P < 0.05). In acute temperature change treatment, hepatopancreas antioxidant enzyme activities, that is, superoxide dismutase (SOD) and catalase (CAT), immune enzyme activities, that is, acid phosphatase (ACP) and lysozyme (LSZ), and heat-shock protein 70 gene (Hsp70) expression levels of scallops increased substantially within 48 h. Significant increases in SOD, CAT, ACP and LSZ activities, and malondialdehyde content occurred under exposure to fluctuating temperatures (P < 0.01). Gill and hepatopancreatic Hsp70 expression levels also increased significantly in response to water temperature fluctuations (P < 0.05). The study provides basic knowledge about thermal stress in Zhikong scallop and may contribute to the management of scallop mortalities.

Dietary biofloc supplementation in black tiger shrimp,Penaeus monodon: effects on immunity, antioxidant and metabolic enzyme activities

A 60-day indoor experiment was conducted to study the effect of dietary supplementation of biofloc on metabolic enzyme activities and immune responses in Penaeus monodon juveniles. Biofloc developed in indoor fibreglass-reinforced plastic (FRP) tanks (1000 L) was used as dietary supplement in P. monodon (2.90 ± 0.10 g) reared in 1000-L FRP tanks. Graded level of dried biofloc was included in shrimp basal diets, 0% (control, B0), 4% (B4), 8% (B8) and 12% (B12). The level of metabolic enzymes like malate dehydrogenase (MDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was not significantly different with control up to 8% dietary supplementation. A higher level of total haemocyte count (THC) was noticed in B8 (22.16 ± 2.17 × 106 cells mL−1) and B4 (21.11 ± 0.56 × 106 cells mL−1) compared with control, C (14.61 ± 2.74 × 106 cells mL−1). Biofloc-supplemented groups recorded significantly higher (P < 0.05) serum SOD and catalase activity (P < 0.01) in comparison with control. The groups fed with 4% dietary biofloc supplement recorded highest relative percentage survival (RPS), 45% after challenge with Vibrio harveyi followed by 36% and 27% RPS in B8 and B12 groups. Based on these results, it can be concluded that supplementation of biofloc even at 4% level in the feed improves immune responses and metabolic activities in black tiger shrimp juveniles.

Effects of fulvic acid on growth performance and intestinal health of juvenile loach Paramisgurnus dabryanus (Sauvage)

A 60-day feeding trial was conducted to determine the effect of dietary fulvic acid supplements on intestinal digestive activity (enzymatic analysis), antioxidant activity, immune enzyme activity and microflora composition of juvenile loach (initial weight of 6.2 ± 0.1 g) reared in experimental aquaria. Five test diets containing 0, 0.5, 1.0, 1.5, and 2% fulvic acid were randomly assigned to three aquaria, respectively. Elevated growth performance including final weight, weight gain (WG), specific growth rate (SGR) and feed conversion ratio (FCR) was observed in loaches that were fed fulvic acid. Maximal weight gain rates and specific growth rates occurred at the 1.5% additive level. The optimal dietary fulvic requirement for maximal growth of juvenile loach is 16.4 g per kg of the diet based on the quadratic regression analysis of specific growth rate against dietary fulvic acid levels. Furthermore, intestinal protease activity, antioxidant activity, lysozyme activity (LZM), complement 3 (C3) content, immunoglobulin M (IgM) content, acid phosphatase activity (ACP) and alkaline phosphatase activity (AKP) were significantly elevated with concomitant increasing levels of dietary fulvic acid. Following a deep sequencing analysis, a total of 42,058 valid reads and 609 OTUs (operational taxonomic units) obtained from the control group and the group displaying the most optimal growth rate were analyzed. Fulvic acid supplementation resulted in an abundance of Firmicute and Actinobacteria sequences, with a concomitant reduction in the abundance of Proteobacteria. Results indicated that fulvic acid supplementation resulted in a reduction in the relative abundance of Serratia, Acinetobacter, Aeromonas and Edwardsiella, and a relative increase in the abundance of Lactobacillus in the intestine. In conclusion, these results suggest that fulvic acid improves growth performance and intestinal health condition of loach, indicates that fulvic acid could be used as an immunoenhancer in loach culture.

Effect of dietary Rhodotorula mucilaginosa on growth performance, digestive and immune enzymes activities of juvenile Nile tilapia (Oreochromis niloticus)

Effect of dietary Rhodotorula mucilaginosa on growth performance, digestive and immune enzymes activities of juvenile Nile tilapia (Oreochromis niloticus)

Beta 1,3/1,6-glucan and vitamin C immunostimulate the non-specific immune response of white shrimp (Litopenaeus vannamei)

This study mainly evaluated the effects of orally administered beta 1,3/1,6-glucan and vitamin C on the nonspecific immune responses of white shrimp (Litopenaeus vannamei). In this study, we found that the white shrimp oral administration with 1 g/kg of beta 1,3/1,6-glucan effectively enhanced O2− production and phenoloxidase and superoxide dismutase activity. Shrimp were oral administration with 0.2 g/kg of vitamin C presented beneficial nonspecific immune responses and enzyme activity and also observed in the beta 1,3/1,6-glucan treatment groups. Consequently, we compared the alterations in the immune activity between the beta 1,3/1,6-glucan and vitamin C groups and the evidence illustrated that combination of beta 1,3/1,6-glucan and vitamin C presented an additive effect on inducing the nonspecific immune responses of white shrimp.

Effects of Dietary Lysine Levels on Growth, Intestinal Digestive Enzymes, and Coelomic Fluid Nonspecific Immune Enzymes of Sea Cucumber, Apostichopus japonicus, Juveniles

AbstractA 56‐d feeding trial was conducted to evaluate the effects of dietary lysine levels on growth performance, intestinal digestive enzymes, and nonspecific immune response of Apostichopus japonicus juveniles. Five semipurified diets were formulated to contain graded levels of lysine (from 0.28 to 2.32% of dry matter). Although no significant differences (P &gt; 0.05) were observed in survival rate, final weight (FW), and body weight gain (BWG), the FW and BWG increased from 0.28 to 1.19% with increasing dietary lysine levels, then showed a declining tendency. Broken‐line regression analysis of BWG indicated sea cucumber requires lysine at 0.76% of dry diet. Proximate composition, lysine content of the body wall, and total amino acid profiles were not affected by dietary treatments. Intestinal protease level increased with increasing dietary lysine level from 0.28 to 1.19%, then decreased. Acid phosphatase and superoxide dismutase activities of the sea cucumbers were not affected by various dietary lysine levels; however, significantly (P &lt; 0.05) higher alkaline phosphatase activity was observed in sea cucumbers fed 2.32% lysine diet than those fed diets having 0.28 and 1.89% lysine. Overall, sea cucumber juveniles fed with diets containing between 0.76 and 1.19% lysine showed better growth performance, digestive enzymes, and nonspecific immune enzyme activities.

Beneficial effects of benthic diatoms on growth and physiological performance in juvenile sea cucumber Apostichopus japonicus (Selenka)

Benthic diatoms are considered a key dietary component, particularly for early juvenile sea cucumber. Physiological effects of benthic diatoms on growth of juvenile sea cucumber Apostichopus japonicus (2.55 g, average initial wet body weight) fed with a formulated diet (the control), Navicula sp., Nitzschia sp., and a mixture of both species (1:1 dry weight) were evaluated. Frozen-thawed diatom paste served as feed for juvenile sea cucumber. All animals exhibited active feeding behavior and diatom frustules occurred in their feces. Our results revealed that specific growth rates (SGRs) of juvenile sea cucumber fed on benthic diatoms were higher than those of the control. The highest SGR (1.41 ± 0.30 % day−1) was found in juvenile sea cucumber fed on Navicula sp. and the SGR of juveniles fed on Nitzschia sp. came second (0.73 ± 0.10 % day−1), showing no significant difference with that of mixed diatoms (0.72 ± 0.12 % day−1). Based on activity of intestine digestive enzyme and coelomic fluid immune enzyme, juveniles fed on Navicula sp. contained higher levels of amylase, protease, and lipase, as well as lysozyme, acid phosphatase, alkaline phosphatase, and superoxide dismutase in the late growth stage than those in the early growth stage, while their protease, amylase, alkaline phosphatase, and catalase activity was significantly higher than that of the control. These results indicated that the benthic diatom Navicula sp. had a positive effect on growth of juvenile sea cucumber probably by enhancing digestive and immune enzyme activities. This information could assist in the development of appropriate diets and feed ingredients for cultured holothurians.

The effects of a dietary protease‐complex on performance, digestive and immune enzyme activity, and disease resistance of Litopenaeus vannamei fed high plant protein diets

The effects of a dietary protease-complex on growth performance, body composition, digestive and immune enzyme activity of Litopenaeus vannamei and its resistance to a pathogenic Vibrio parahaemolyticus were assessed in a 9-week trial. A high fish meal diet (HF) containing 200 g kg−1 fish meal and a low fish meal diet (LF) containing 100 g kg−1 fish meal were designed as a positive and negative control respectively. Three other diets (LF+125P, LF+150P, and LF+175P) were manufactured by supplementing graded level of a protease-complex (125, 150 and 175 mg kg−1, respectively) to the LF diet. All diets were formulated to be iso-proteic and iso-energetic. Most performance indices of shrimp fed the LF+175P diets were similar to the HF diet. Among the digestive enzymes, trypsin, lipase and amylase activity in hepatopancreas of shrimp fed LF+175P diets (4576 U mg−1 protein and 16, 32 U g−1 protein, respectively) were higher than those fed the LF diets but lower than the HF diets (P < 0.05). Total superoxide dismutase and polyphenol oxidase contents in both serum and hepatopancreas were higher and serum malondialdehyde content and the cumulative mortality during disease challenge tests were lower for the diets containing the protease-complex than those fed the LF diets (P < 0.05) with no difference with those fed the HF diets.

Effects of dietary inclusion of benthic matter on feed utilization, digestive and immune enzyme activities of sea cucumber Apostichopus japonicus (Selenka)

A 70-day feeding experiment was conducted to examine the effects of dietary inclusion of benthic matter, which was mainly composed of microalgae, bacteria and clay particles, on the feed utilization, digestive and immune enzyme activities of sea cucumber Apostichopus japonicus. Sea cucumbers were fed with 6 types of diets with the ingredient of either single algae species or mixture of algae and benthic matter, i.e., single brown alga Sargassum muticum, red alga Gracilaria lemaneiformis, green alga Ulva lactuca, mixtures (1:1) of S. muticum and benthic matter, G. lemaneiformis and benthic matter and U. lactuca and benthic matter. After the feeding trial, the feed utilization efficiency, digestive and immune enzyme activities of A. japonicus were remarkably affected by different types of diets. The feed conversion ratio of A. japonicus fed the single G. lemaneiformis was significantly higher than those fed with single S. muticum and those fed on G. lemaneiformis with benthic matter (ANOVA, p<0.05). While the protein efficiency ratios of A. japonicus fed the single algae diets were significantly lower relative to those fed on corresponding mixed diets (ANOVA, p<0.05). The trypsin activity of A. japonicus that fed the single G. lemaneiformis was not only significantly lower than those fed the single S. muticum and single U. lactuca but also significantly lower than those fed on G. lemaneiformis with benthic matter (ANOVA, p<0.05). The amylase and cellulase activities of A. japonicus that fed the single algae diets were significantly lower as compared to the corresponding mixed diet groups (ANOVA, p<0.05). Similarly, the superoxide dismutase and acid phosphatase activities of A. japonicus that fed the single algae diets were significantly lower relative to those fed on corresponding mixed diets (ANOVA, p<0.05). While the alkaline phosphatase activity of A. japonicus fed on G. lemaneiformis with benthic matter was not only significantly higher than those fed the G. lemaneiformis alone but also significantly higher than those fed on S. muticum with benthic matter and U. lactuca with benthic matter (ANOVA, p<0.05). The results of the present study suggested that dietary inclusion of benthic matter might have beneficial effects on the digestive processes, immune responses and growth performance of A. japonicus. Statement of relevanceThe results of the present study can provide the scientific suggestions for optimizing the feed ingredients for farming of sea cucumber A. japonicus.

Effect of white spot syndrome virus (WSSV) infection on immune enzyme activity and ultrastructure in the haemolymph tissue of Cherax quadricarinatus (Decapoda, Astacidea)

To explore the pathogenic mechanism of white spot syndrome virus (WSSV) in crayfish (Cherax quadricarinatus), we analysed activities of the three immune-related enzymes PO, SOD and LSZ in haemolymph tissue ofC. quadricarinatusbefore and after infection, and simultaneously studied the ultrastructural pathology. The results show that WSSV infection affects activities of the three enzymes. After 6-24 h of WSSV infection, the activities of PO, SOD and LSZ increased, but decreased significantly during longer infection times. The enzyme activities in WSSV-infected crayfish were significantly lower than those in controls at 72 h, except for LSZ (). Interestingly, the activities of PO, SOD and LSZ in the group treated with immune-polysaccharides before challenge with WSSV were higher than in the directly infected group, and the immune protection rate reached 51.9%, suggesting that the polysaccharides could improve enzyme activities and enhance antiviral defences of the organism. Ultrastructural pathological changes showed damaged haemolymph tissue, deformed golgiosomes, fuzzy damage in the mitochondrial structures, and nuclear membrane deformation and fracture. High levels of heterochromatin appeared in the nucleus; organoid and chromatin dissolved in dying blood cells, cytoplasm appeared oedematous and cells dissolved. WSSV particles were visible in blood cell nuclei of infected crayfish.

Reconfiguration of the immune system network during food limitation in the caterpillar Manduca sexta.

Dwindling resources might be expected to induce a gradual decline in immune function. However, food limitation has complex and seemingly paradoxical effects on the immune system. Examining these changes from an immune system network perspective may help illuminate the purpose of these fluctuations. We found that food limitation lowered long-term (i.e. lipid) and short-term (i.e. sugars) energy stores in the caterpillar Manduca sexta. Food limitation also: altered immune gene expression, changed the activity of key immune enzymes, depressed the concentration of a major antioxidant (glutathione), reduced resistance to oxidative stress, reduced resistance to bacteria (Gram-positive and -negative bacteria) but appeared to have less effect on resistance to a fungus. These results provide evidence that food limitation led to a restructuring of the immune system network. In severely food-limited caterpillars, some immune functions were enhanced. As resources dwindled within the caterpillar, the immune response shifted its emphasis away from inducible immune defenses (i.e. those responses that are activated during an immune challenge) and increased emphasis on constitutive defenses (i.e. immune components that are produced consistently). We also found changes suggesting that the activation threshold for some immune responses (e.g. phenoloxidase) was lowered. Changes in the configuration of the immune system network will lead to different immunological strengths and vulnerabilities for the organism.

Pathology and physiology of Haliotis diversicolor with withering syndrome

Abalone withering syndrome is a serious chronic disease. Ultrastructure and pathological changes were studied using transmission electron microscopy. Myofibers appeared hollow, and the number of inner intact myofibrils was reduced greatly. The morphology of mitochondria in cells appeared abnormal. Crystal lattice-like inclusions in pathological muscle cells were observed. The hepatopancreas was damaged severely; it was full of empty vesicles and devoid of any recognizable cellular structures. The activities of 3 enzymes, acid phosphatase (ACP), alkaline phosphatase (AKP), and total superoxide dismutase (T-SOD), in hemolymph of healthy and diseased abalone showed little differences. ACP activity in the pedal mucus of healthy and diseased abalone was not significantly different. However, in diseased abalone pedal mucus, activities of AKP and T-SOD were significantly lower than in the control group. In pedal mucus of healthy and diseased abalone, the differential (SDS-PAGE) bands were identified as actin and hemocyanin. Protein identification was accomplished with mass spectrometry. A total of 16 2-DE gel spots were identified; 5 gel spots showed upregulation and 11 gel spots showed downregulation in diseased abalone. Proteins involved in energy production and storage, including fructose-1, 6-bisphosphate aldolase, arginine kinase, and triosephosphate isomerase, showed diverse expression patterns in diseased abalone. For stress-responsive proteins, expression of Cu/Zn-superoxide dismutase showed downregulation. For contraction and regulation proteins of muscle, actin showed significant downregulation. Statement of relevanceAbalone withering syndrome (WS) is a serious chronic disease. However, there is limited information on the physiological performance of infected abalones. The present study was to assess the alterations of Haliotis diversicolor caused by WS using transmission electron microscopy as well as assess the immune enzyme activity of hemolymph and mucus, and muscle, mucus proteins changes by 2-DE and SDS-PAGE.

Phytochemicals in Morinda citrifolia fruit selectively modulate age-associated immunity and antioxidant enzyme activities through ERK pathway in splenic lymphocytes of male F344 rats

Context/objective: The mechanisms of immunomodulatory effects of Morinda citrifolia (Noni) were examined through intracellular signaling pathways in the splenocytes and their modulation by phytochemicals using bioinformatics tools. Materials and methods: Noni fruit juices without seeds (NSL) and with seeds (NWS) were co-incubated in vitro with splenocytes from young, middle-aged and old F344 male rats and proliferation of lymphocytes, cytokine production, antioxidant enzyme activities and intracellular signaling markers were measured. Results: NSL decreased lymphoproliferation in early middle-aged rats, and IL-2 and IFN-γ production in old rats. In contrast, NWS enhanced lymphoproliferation in young and old rats, IL-2 and IFN-γ production in middle-aged and old rats. The activities of antioxidant enzymes were augmented by NWS and NSL in old rats. NWS reversed age-related increase in lipid peroxidation in all age-groups, while NSL increased lipid peroxidation in old rats. NSL increased p-ERK in old rats and decreased p-CREB in young and middle-aged rats. In contrast, NWS decreased p-ERK in all age groups and increased p-CREB in old rats. Both NSL and NWS increased p-Akt expression in middle-aged and old rats. Both NSL and NWS suppressed p-NF-κB expression in middle-aged and old rats. Docking studies demonstrated that Noni phytochemicals, damnacanthal, myricetin and ursolic acid, are potent inhibitors of ERK with binding sites in the catalytic and phosphorylation sites of the molecule. Conclusions: These results suggest that Noni fruit juices with or without seeds modulate cell-mediated immunity and antioxidant enzyme activities based on the phytochemicals that may differentially influence cell signaling and therefore, age-associated immunity.

The lipopolysaccharide (LPS) of Photorhabdus luminescens TT01 can elicit dose- and time-dependent immune priming in Galleria mellonella larvae

In this work, we primed Galleria mellonella larvae by haemocoel injection of lipopolysaccharide (LPS) extracted from Photorhabdus luminescens TT01 to determine whether bacterial LPS can induce enhanced immune protection (recently called immune priming). We also analyzed the relationship between changes in the levels of innate immune elements and the degree of enhanced immune protection in the larvae at designated time points after priming. The larvae that received experimental doses (20.0, 10.0 and 5.0μg per larva) of LPS demonstrated increased resistance against lethal challenge with P. luminescens TT01; the degree and period of protection correlated positively with the priming dose. These results indicated that the P. luminescens TT01 LPS could induce typical immune priming in G. mellonella. Moreover, the levels of innate immune parameters (i.e. haemocyte density, phagocytosis, haemocyte encapsulation ability, and antibacterial activity of cell-free haemolymph) and endogenous enzyme activities (i.e. acid phosphatase, ACP; alkaline phosphatase, AKP; superoxide dismutase, SOD and lysozyme, LSZ) were significantly increased following priming of the larvae with LPS, whereas the activities of peroxidase (POD) and catalase (CAT) were significantly decreased. All of the parameters examined changed in a dose- and time-dependent manner. This study demonstrated that G. mellonella larvae could modulate their immune responses based on different doses of LPS used for priming, and that priming phenomenon in G. mellonella larvae elicited by LPS was mediated by the innate immune elements and enzyme activity.

Effect of oxidized fish oil and α-tocopherol on growth, antioxidation status, serum immune enzyme activity and resistance toAeromonas hydrophilachallenge of Chinese mitten crabEriocheir sinensis

The impact of dietary α-tocopherol on juvenile Chinese mitten crab Eriocheir sinensis was experimentally evaluated in a 10-week study. Crab were fed with nine diets including three levels of α-tocopherol (0, 100 and 300 mg kg−1 diet) and three levels of fish oil oxidation (fresh, moderate and high) in triplicates. Fresh and moderate oil oxidization enhanced weight gain, but moderate and high oil oxidization lowered survival and feed efficiency. The 100-mg α-tocopherol kg−1 diet resulted in higher hepatopancreas MDA than other α-tocopherol diets. High oil oxidization led to the lowest serum superoxide dismutase (SOD) and glutathione peroxidase (GPH-PX). The serum SOD and GPH-PX activities in crab fed 100 mg α-tocopherol were higher than in those fed other α-tocopherol diets. The diet without α-tocopherol addition lowered lysozyme and phenoloxidase (PO) activities compared to other α-tocopherol diets. Fresh fish oil diet increased PO activity compared to oxidized oils. High oil oxidization caused significantly more mortality than fresh or moderate oxidization after 7-d postchallenge with Aeromonas hydrophila. Supplementation with α-tocopherol significantly enhanced resistance to bacterial infection. This study indicates that α-tocopherol can protect lipid from peroxidation and enhance disease resistance.

Striped murrel S1 family serine protease: immune characterization, antibacterial property and enzyme activities

We report a molecular characterization of S1 family serine protease (SP-1) from snakehead murrel (or called striped murrel) Channa striatus (Cs). CsSP-1 polypeptide contained a catalytic core domain (otherwise known as serine protease trypsin domain) between H20 and I237 along with a catalytic triad at H61, D104 and S197. Phylogenetic analysis confirmed that CsSP-1 belongs to serine protease S1 family. The tertiary structure showed that CsSP-1 contains 14 β-sheets as 2 separate β-barrels (the first β-barrel consists of 8 β-sheets in the N-terminal region and the second β-barrel consists of 6 β-sheets in the C-terminal region) and 3 α-helical regions. Significantly (P < 0.05) the highest CsSP-1 mRNA expression was observed in intestine, liver and kidney, moderate expression was seen in spleen, head kidney, skin and blood, and the lowest one in brain, gill, muscle and heart. Further, the expression was induced in intestine with fungus Aphanomyces invadans and bacteria Aeromonas hydrophila. The recombinant CsSP-1 protein showed antibacterial activity against both gram-negative and gram-positive bacteria. The optimum CsSP-1 enzyme activity against the substrate casein was determined at 8 mM casein concentration. Moreover, the activity was highly influenced by 5 mM phenyl-methylsulfonyl fluoride followed by ethylenediaminetetraacetic acid, 4-(2-aminoethyl)benzenesulfonylfluoride hydrochloride and calpain inhibitor I. The CsSP-1 enzyme exhibited the highest activity at pH 7.5 and temperature 35°C. The overall results showed the potential involvement of CsSP-1 in the immune system of murrels. However, further research is necessary to study the mechanism of implicit trypsin association in the defence process.

Prophenoloxidase system, lysozyme and protease inhibitor distribution in the common cuttlefish Sepia officinalis

The immune system of cephalopods remains poorly understood. The aim of this study was to determine the specific activity of immune enzymes in epithelial barriers, circulatory and digestive systems of the common cuttlefish Sepia officinalis. Three enzyme groups with putative functions in immunity were investigated: phenoloxidases (POs), lysozymes and protease inhibitors (PIs). Consistent with a role in immunity, highest PO activities were found in the integument as well as the respiratory and circulatory organs under zymogenic (proPO) and active form. Surprisingly, high PO activities were also found in the digestive gland and its appendages. Similarly, high lysozyme activities were detected in the integument and circulatory organs, but also in the posterior salivary glands, highlighting the implication of this antibacterial enzyme group in most tissues exposed to the environment but also within the circulatory system. Albeit highest in digestive organs, the ubiquitous detection of PI activity in assayed compartments suggests immune function(s) in a wide range of tissues. Our study reports proPO/PO, lysozyme and PI distributions in S. officinalis body compartments for the first time, and thus provides the fundamental basis for a better understanding of the humoral immune system in cephalopods as well as invertebrates.

White spot syndrome virus strains of different virulence induce distinct immune response in Cherax quadricarinatus

In this study, we identified three white spot syndrome virus (WSSV) strains (WSSV-CN01, WSSV-CN02 and WSSV-CN03) with significant differences in virulence. Among them, WSSV-CN01 caused significant higher and earlier mortality in redclaw crayfish Cherax quadricarinatus, thus was determined as high-virulent, while WSSV-CN02 and WSSV-CN03 were moderate-virulent and low-virulent. By investigating the total number of the circulating haemocytes and the activity of immune relative enzymes, we demonstrated that the different virulent WSSV strains induced distinct immune response in the host. Notably, a dramatic reduction of circulating haemocytes was observed in the crayfish infected with WSSV-CN01 and WSSV-CN02 but not WSSV-CN03. Further analysis revealed that cell death induced by WSSV-CN01 and WSSV-CN02 might be responsible for the decrease of circulating haemocytes.

Effects of dietary cholesterol levels on moulting performance, lipid accumulation, ecdysteroid concentration and immune enzymes activities of juvenile Chinese mitten crabEriocheir sinensis

Effects of dietary cholesterol levels on moulting performance, lipid accumulation, ecdysteroid concentration and immune enzymes activities of juvenile Eriocheir sinensis were investigated. Crabs were fed with feeds contained various cholesterols of 1100, 2100 and 3200 mg kg−1 in both paddy fields and laboratory experiments. In paddy fields trial, the crabs fed with diets contained 3200 mg kg−1 cholesterol achieved higher growth rate than those fed with diets contained no supplemental cholesterol (1100 mg kg−1). In laboratory trial, moulting frequencies of crabs fed with diets contained 3200 mg kg−1 cholesterol were higher than those of crabs fed with diets contained no supplemental cholesterol from the 6th to 10th moult. Further laboratory experiment indicated that intermoults of crabs fed with diets contained 3200 mg kg−1 cholesterol significantly shortened compared with crabs fed with the basal feeds (1100 mg kg−1 cholesterol). In the intermoult, total lipid content, ecdysterone concentration and three immune enzymes in crabs were increased with the increment of dietary cholesterol levels between the 7th and the 8th moult in laboratory experiments. Taken together, dietary cholesterol not only enhanced moulting performances of growth, survival and moult frequency, but also enhanced total lipid storage, ecdysterone concentration and three immune enzymes activities in the intermoult period.