Identification and cloning of a transglutaminase from giant freshwater prawn, Macrobrachium rosenbergii, and its transcription during pathogen infection and moulting

Immunopathogenesis of hematopoietic tissues in response to Vibrio parahaemolyticus (VPAHPND) infection in Macrobrachium rosenbergii

In crustacean, hemocytes are known as crucial components of crustaceans' innate immunity against pathogens. Drastic hemocytes reduction during infectious disease is apparently related to disease severity and calls for a health status evaluation and aquaculture management. The molecular pathogenesis of hemocytes loss during bacterial infection was elucidated with VP_AHPND challenged in M. rosenbergii. We report herein a correlation between hemocyte loss and the pathogenicity and aggressive immune response in hematopoietic tissues of moribund M. rosenbergii. In this study, adult freshwater prawn was administered an LC₅₀ dose of VP_AHPND; bacterial clearance ensued, and success was reached within 24 h. Hemocytes increased in survival, yet drastically decreased in moribund prawn. Pathological analysis of hematopoietic tissue of moribund prawn showed apparent abnormal signs, including the presence of bacteria, a small number of mitotic cells, cellular swelling, loosening of connective tissue, and karyorrhectic nuclei cells. A significant upregulation of a core apoptotic machinery gene, caspase-3, was detected in hematopoietic tissue of moribund shrimp, but not in those of Escherichia coli DH5α (non-pathogenic bacteria) and VP_AHPND survival prawn. The highest level was found in the moribund group, which confirms the occurrence of apoptosis in this hematopoietic tissue. Further, our results suggest that hematopoietic tissue damage may arise from inflammation triggered by an aggressive immune response. Immune activation was indicated by the comparison of immune-related gene expression between controls, E. coli (DH5α)-infected (non-pathogenic), and VP_AHPND-infected survival groups with moribund prawn. RT-PCR revealed a significant upregulation of all genes in hematopoietic tissues and hemocytes within 6-12 h and declined by 24 h. This evident related to the almost VP_AHPND are clearance in survival and E. coli (DH5α) challenged group in contrast with drastic high expression was determined in moribund group. We conclude that a reduction of renewing circulating hemocytes in fatally VP_AHPND-infected prawn was caused by an acute self-destructive immune response by hematopoietic cells.

Dietary supplementation of host‐associated lactic acid bacteria modulates growth, metabolic activities, and immune‐related gene expression in giant freshwater prawn, Macrobrachium rosenbergii

The present study was carried out to evaluate the dietary effects of host‐associated lactic acid bacteria on growth performance, metabolic enzyme activities, and immune response of Macrobrachium rosenbergii juveniles. To formulate the test diets, a control (Con) diet was supplemented with a commercial probiotic and three host‐derived bacteria Enterococcus faecalis (EC), Lactococcus lactis I (LC‐I), and L. lactis II (LC‐II), which were previously isolated from the gastrointestinal tract of adult individuals of M. rosenbergii. Juvenile M. rosenbergii (0.65 ± 0.008 g) were randomly stocked at 20 individuals/100 L of fiberglass tanks with three replications for each test diet. After 50 days, juveniles fed the diets LC‐I and LC‐II showed significantly higher (p < .05) weight gain, specific growth rate, and the lowest feed conversion ratio. The analyses of glutamic oxaloacetate transaminase and glutamic pyruvate transaminase in muscle and hepatopancreas revealed significantly (p < .05) reduced values in LC‐I fed juveniles. The total hemocyte count and phenoloxidase activity were significantly increased (p < .05) in LC‐I and LC‐II fed juveniles. The relative mRNA expression patterns of immune‐related α2‐M, LGBP, ProPO, Cu, Zn‐SOD, TG, PE, AKP, and ACP genes were significantly (p < .05) upregulated in juveniles fed with LC‐I followed by the diet LC‐II. Finally, the study suggests that the growth performance and immune response of M. rosenbergii can be improved through supplementation of host‐associated L. lactis bacteria for its higher production.

Transglutaminase 1 and 2 are localized in different blood cells in the freshwater crayfish Pacifastacus leniusculus

In the present study we show that hemocytes in the freshwater crayfish Pacifastacus leniusculus express two different transglutaminases. We describe the sequence of a previously unknown TGase (Pl_TGase1) and named this as Pl_TGase2 and compared this sequence with similar sequences from other crustaceans. The catalytic core domain is similar to the previously described TGase in P. leniusculus, but Pl_TGase2 has significant differences in the N-terminal and C-terminal domains. Further, we show conclusive evidences that these different transglutaminases are specific for different hemocyte types so that Pl_TGase1 is expressed in the hematopoietic tissue and in the cytoplasm of semigranular hemocytes, while Pl_TGase2 is expressed in vesicles in the granular hemocytes. By in situ hybridization we show that both Pl_TGase1 and Pl_TGase2 mRNA are present only in a subset of the respective hemocyte population. This observation indicates that there may be different subtypes of semigranular as well as granular hemocytes which may have different specific functions.

Transcriptomic responses of the clam Meretrix meretrix to the organophosphorus pesticide (dimethoate)

Organophosphorus pesticides (OPs) play a certain role in promoting the development of agriculture and forestry, but they may cause potential harm to aquatic life when entering rivers and polluting water sources. Previous researches have shown that OPs participate in the regulation mechanism of aquatic organisms. Here, our aim is to determine the underlying mechanisms of one OP (dimethoate) at the transcriptional level using the clam Meretrix meretrix. 4119 DEGs were obtained from high-throughput RNA sequencing data. Then, expression profiles of some genes were verified by qPCR, which showed a positive correlation with the RNA sequencing results. 14,481 simple sequence repeats were also identified and could be further used as molecular markers. In addition, some oxidative, immune, and stress-related genes were further discussed and could also be used as biomarkers to indicate the biological response of dimethoate. This study will help to better understand the clam's response mechanism to dimethoate stress.

Cell surface transglutaminase required for nodavirus entry into freshwater prawn hemocytes

To identify molecules involved in Macrobrachium rosenbergii nodavirus (MrNV) entry into hemocytes of the giant freshwater prawn M. rosenbergii, biotinylated prawn hemocyte membrane proteins were prepared, purified and separated by SDS-PAGE. The proteins were blotted on the nitrocellulose membrane before incubation with the MrNV capsid protein (MrNV-CP) by a VOPBA technique. Subsequent mass spectrometry and analysis of immune-reactive bands represent putative binding partners including transglutaminase (TG), actin, α2-macroglobulin, α1-tubulin, F₁-ATP synthase β-subunit and a currently uncharacterized protein. The sequence of TG has been characterized and found 5 amino acids differences to a previously reported MrTG (ADX99580), mainly at its N-terminal part and thus, we named it MrTGII (KM008611). Recombinant MrTGII was prepared to produce a polyclonal antibody against it, which was successfully revealed the presence of MrTGII (100 kDa) in prawn hemocyte lysates. Using the pentylamine-biotin incorporation assay, an acyl transfer reaction was observed when hemocyte lysates were added to solutions containing MrNV-CP, suggesting that hemocyte MrTG could use MrNV-CP as the substrate. The expression levels of MrTGII were changed during the course of MrNV infection. By using immunostaining technique, location of MrTGII on the hemocyte surface was confirmed. Specific interaction between MrTGII with MrNV-CP in a dose-dependent manner was confirmed by in vitro ELISA assay. The highest binding activity of MrNV-CP was found with the N-terminal portion of the protein. In vitro neutralization using anti-MrTGII antibody resulted in inhibition of MrNV attachment to the hemocyte surface, accompanied by a dramatic reduction in viral replication. This is the first time that crustacean TG has been shown to be involved in viral entry, in addition to its roles in blood clotting and haematopoiesis.

Functional domains of Litopenaeus vannamei transglutaminase and their involvement in immunoregulation in shrimp

Shrimps, which mainly rely on their innate immune system to response to infectious pathogens, have clottable proteins as an important component of this system. While transglutaminases (TGase) are found in Litopenaeus vannamei and constitute part of the coagulation system, the specific immune-related roles played by its functional domains in the immunoregulation of shrimp has not been well understood. In the present study, we report that the Ig-like domain of L. vannamei transglutaminase (TGase-C) is the main immune-related domain among the three functional domains, as it had higher bacterial agglutinative activity against Vibrio parahaemolyticus and Streptococcus iniae. Using Co-immunoprecipitation and LC-MS/MS analysis, TGase-C was shown to interact with 474 proteins, of which 52 proteins were annotated to L. vannamei. More than half of the L. vannamei annotated proteins have immune-related functions, including apoptosis. Further analysis using pull-down assay revealed that TGase-C interacted with CAP-3 (a homologue of caspase 3). In addition, siRNA-mediated knockdown of LvTGase significantly (p < 0.01) increased the expression level of LvCAP-3 coupled with a significant (p < 0.01) increase in caspase 3/7 activity, suggesting that probably LvTGase participates in shrimp immune response by modulating the activity of LvCAP-3. These findings thus suggest the Ig-like functional domain of L. vannamei's transglutaminase is the domain that is involved in immunoregulation in shrimp.

Changes of Ammonia-Metabolizing Enzyme Activity and Gene Expression of Two Strains in Shrimp Litopenaeus vannamei Under Ammonia Stress

Ammonia stress can inhibit the survival and growth, and even cause mortality of shrimp. In this study, ammonia-metabolizing enzyme activities and gene expression were compared between two strains of L. vannamei under different ammonia-N (NH4+) concentrations (3.4, 13.8, and 24.6 mg/L). The results showed that elevated ammonia concentrations mainly increased glutamine synthetase (GSase) activities while inhibiting transglutaminase (TGase) activities in the muscle of both strains. Thus, we concluded that L. vannamei could accelerate the synthesis of glutamine from glutamate and NH4+ to alleviate ammonia stress. Compared with the muscle, the hepatopancreas plays a major role in ammonia stress and might be a target tissue to respond to the ammonia stress. Compared to the control group, the treatment of high ammonia concentrations reduced the hepatopancreas TGase (TG) gene expression and increased the gene expression rates of glutamate dehydrogenase-β (GDH-β) and GSase (GS) in both the muscle and the hepatopancreas of the two strains (p < 0.05). These genes (GDH-β and GS) in strain B were not only expressed earlier but also at levels higher than the expression range of strain A. At the gene level, strain B showed a more rapid and positive response than strain A. These data might help reveal the physiological responses mechanisms of shrimp adapt to ammonia stress and speed up the selective breeding process in L. vannamei.

Impacts of environmental and biological stressors on immune system of Macrobrachium rosenbergii

Macrobrachium rosenbergii commonly called giant freshwater prawn is a widely farmed crustacean in freshwater. Similar to other aquatic organisms, their growth and well‐being is influenced by various physical, chemical and biological factors. We discuss about the critical growth limiting factors as well as disease causing agents and the potential immune molecules of M. rosenbergii that are proved to involve in preventing and/or responding to those limiting factors.

Assessing the relevance of a multiplexed methodology for proteomic biomarker measurement in the invertebrate species Gammarus fossarum: A physiological and ecotoxicological study

Recently, a protein sequence database was built specifically for the sentinel non-model species Gammarus fossarum using a proteogenomics approach. A quantitative multiplexed targeted proteomics assay (using Selected Reaction Monitoring mass spectrometry) was then developed for a fast and simultaneous quantification of dozens of biomarker peptides specific of this freshwater sentinel crustacean species. In order to assess the relevance of this breakthrough methodology in ecotoxicology, the response patterns of a panel of 26 peptides reporting for 20 proteins from the Gammarus fossarum proteome with putative key functional roles (homeostasis, osmoregulation, nutrition, reproduction, molting,…) were recorded through male and female reproductive cycles and after exposure to environmental concentrations of cadmium and lead in laboratory-controlled conditions. Based on these results, we validated the implication of annotated vtg-like peptides in the oogenesis process, and the implication of Na⁺/K⁺ ATPase proteins in the molt cycle of organisms. Upon metal (cadmium and lead) contamination, peptides belonging to proteins annotated as involved in antioxidant and detoxification functions, immunity and molting were significantly down-regulated. Overall, this multiplex assay allowed gaining relevant insights upon disruption of different main functions in the sentinel species Gammarus fossarum. This breakthrough methodology in ecotoxicology offers a valid and high throughput alternative to currently used protocols, paving the way for future practical applications of proteogenomics-derived protein biomarkers in chemical risk assessment and environmental monitoring.

The hot-water extract of leaves of noni, Morinda citrifolia, promotes the immunocompetence of giant freshwater prawn, Macrobrachium rosenbergii

The hot-water Morinda citrifolia leaf extract (HMLE) was prepared for in vitro assessment on phenoloxidase (PO) activity, respiratory bursts (RBs), and phagocytic activity (PA). Furthermore, the HMLE was administrated in the diet at 0.6, 3, and 6 g (kg diet)^-1 for Macrobrachium rosenbergii, and the potential effects on the immunocompetence of prawns were evaluated. PO activity, RBs, and PA in hemocytes incubated with the HMLE at 140, 20, 20, and 140 mg l^-1 significantly increased. The immune parameters of the total hemocyte count (THC), differential hemocyte count (DHC), RBs, PO activity, superoxide dismutase (SOD) activity, PA, transglutaminase (TG) activity and hemolymph clotting time were evaluated before and after 1, 3, 5, 7, and 9 weeks of the feeding trial. During 9 weeks of the feeding trial, higher THCs, DHCs, RBs, PO, and TG as well as accelerated clotting times were observed in prawns fed HMLE-containing diets at 0.6 g kg^-1. The mRNA expressions of prophenoloxidase, TG, crustin, and lysozyme of prawns fed HMLE-containing diets at 0.6 g kg^-1 for 9 weeks of the feeding trial significantly increased. The susceptibility of prawns fed the HMLE at 0.6 g kg^-1 to Lactococcus garvieae infection significantly decreased, and the relative survival percentage was 23.1%. We therefore found that HMLE administrated through the diet at 0.6 g kg^-1 was capable of enhancing the immunity and resistance against L. garvieae in M. rosenbergii.

The known two types of transglutaminases regulate immune and stress responses in white shrimp, Litopenaeus vannamei

Transglutaminases (TGs) play critical roles in blood coagulation, immune responses, and other biochemical functions, which undergo post-translational remodeling such as acetylation, phosphorylation and fatty acylation. Two types of TG have been identified in white shrimp, Litopenaeus vannamei, and further investigation on their potential function was conducted by gene silencing in the present study. Total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase activity, respiratory bursts (release of superoxide anion), superoxide dismutase activity, transglutaminase (TG) activity, haemolymph clotting time, and phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were measured when shrimps were individually injected with diethyl pyrocarbonate-water (DEPC-H2O) or TG dsRNAs. In addition, haemolymph glucose and lactate, and haemocytes crustin, lysozyme, crustacean hyperglycemic hormone (CHH), transglutaminaseI (TGI), transglutaminaseII (TGII) and clotting protein (CP) mRNA expression were determined in the dsRNA injected shrimp under hypothermal stress. Results showed that TG activity, phagocytic activity and clearance efficiency were significantly decreased, but THC, hyaline cells (HCs) and haemolymph clotting time were significantly increased in the shrimp which received LvTGI dsRNA and LvTGI + LvTGII dsRNA after 3 days. However, respiratory burst per haemocyte was significantly decreased in only LvTGI + LvTGII silenced shrimp. In hypothermal stress studies, elevation of haemolymph glucose and lactate was observed in all treated groups, and were advanced in LvTGI and LvTGI + LvTGII silenced shrimp following exposure to 22 °C. LvCHH mRNA expression was significantly up-regulated, but crustin and lysozyme mRNA expressions were significantly down-regulated in LvTGI and LvTGI + LvTGII silenced shrimp; moreover, LvTGII was significantly increased, but LvTGI was significantly decreased in LvTGI silenced shrimp following exposure to 28 and 22 °C. Knockdown of LvTGI and LvTGI + LvTGII also significantly increased the mortality of L. vannamei challenged with the pathogen V. alginolyticus. The same consequences have been confirmed in LvTGII silenced shrimp in our previous study. These results indicate that LvTGI and LvTGII not only reveal a complementary effect in gene expression levels but also play a key function in the immune defence mechanism of shrimp, by regulating the haemolymph coagulation, immune parameters and immune related gene expression, and in the regulation of carbohydrate metabolism.

Role of transglutaminase in immune defense against bacterial pathogens via regulation of antimicrobial peptides

Transglutaminase (TGase) is critical for blood coagulation, a conserved immunological defense mechanism among invertebrates. Here, a 3248-bp (full-length) TGase cDNA in Eriocheir sinensis (EsTGase) was cloned, with a 2274-bp open reading frame (ORF) encoding a 757 amino acid protein containing two transglut domains, one TGase/protease-like homolog domain and a KGD (Lys-Gly-Asp) motif. Phylogenetic analysis demonstrated that EsTGase appeared earlier in evolution compared with TGases of other crustaceans and mammals. EsTGase mRNA was mainly detected in hemocytes and up-regulated post-challenge with bacteria (Vibrio parahaemolyticus and Staphylococcus aureus), suggesting an immune function for this gene. Moreover, the EsTGase activity in hemocytes challenged with V. parahaemolyticus and S. aureus was decreased significantly. RNA interference of EsTGase down-regulated expression of immune-related genes CrusEs2, EsLecG and Es-DWD1 with or without bacteria stimulation in vitro. Furthermore, absence of EsTGase led to higher bacterial counts in the hemocyte culture medium. Thus, EsTGase is an important component of the crab immune response and is involved in the regulation of certain immune-related genes, particularly those encoding anti-microbial peptides.

Roles of receptor for activated protein kinase C1 for modulating immune responses in white shrimp Litopenaeus vannamei

Complementary (c)DNA encoding a receptor for activated protein kinase C1 (RACK1) messenger (m)RNA of the white shrimp Litopenaeus vannamei, designated LvRACK1, consisted a 1136-bp cDNA containing an open reading frame (ORF) of 954 bp, a 111-bp 5'-untranslated region (UTR), and a 71-bp 3'-UTR, which is a 36 kDa cytosolic protein, belonging to the Trp-Asp40 (WD40) family of proteins, characterized by containing seven highly conserved Trp-Asp40 (WD40) internal repeats, and a poly A tail. The WD repeat of LvRACK1 can be predicted to form a seven-bladed propeller structure with each WD repeat composed of four antiparallel β-sheets. The WD40 domains have been implicated in protein-protein interactions. A comparison of amino acid sequences showed that LvRACK1 was closely related to arthropods RACK1. LvRACK1 cDNA was synthesized in all tested tissues detected with real-time PCR including haemocytes, hepatopancreas, gills, muscles, subcuticular epithelium, intestines, abdominal nervous ganglia, thoracic nervous ganglia, lymphoid organ, stomach, heart, and antennal gland, especially in subcuticular epithelium and gill. LvRACK1 mRNA transcription in haemocytes of L. vannamei injected with Vibrio alginolyticus decreased. The depletion of LvRACK1 of haemocytes in L. vannamei received its dsRNA revealed the increased respiratory bursts per haemocyte, superoxide dismutase (SOD), activity, glutathione peroxidase (GPx) activity, and clotting time, but showed the decreased total haemocyte count (THC), hyaline cells (HCs), phagocytic activity, and transglutaminase (TG) activity. LvRACK1 silenced shrimp showed the upregulated gene expressions of cyMnSOD, mtMnSOD, peroxinectin (PE), and TGI, and showed the downregulated α2-macroglobulin (α2-M), clottable protein (CP), lysozyme, and crustin gene expressions. It is therefore concluded that LvRACK1 is involved in immune defense and signaling transduction in haemocytes of L. vannamei infected with V. alginolyticus.

The effect of banana (Musa acuminata) peels hot-water extract on the immunity and resistance of giant freshwater prawn, Macrobrachium rosenbergii via dietary administration for a long term: Activity and gene transcription

The non-specific immune parameters, disease resistance and immune genes expressions in Macrobrachium rosenbergii were evaluated at 120 days of post feeding the diets containing the extracts of banana, Musa acuminate, fruit's peel (banana peels extract, BPE) at 0, 1.0, 3.0 and 6.0 g kg(-1). Results showed that prawns fed with a diet containing BPE at the level of 1.0, 3.0 and 6.0 g kg(-1) for 120 days had a significantly higher survival rate (30.0%, 40.0% and 56.7%, respectively) than those fed with the control diet after challenge with Lactococcus garvieae for 144 h, and the respective relative survival percentages were 22.2%, 33.3%, and 51.9%, respectively. Dietary BPE supplementation at 3.0 and/or 6.0 g kg(-1) for 120 days showed a significant increase total haemocyte count (THC), granular cell (GC), superoxide dismutase (SOD) activity, phenoloxidase (PO) activity, transglutaminase (TG) activity, and phagocytic activity and clearance efficiency to L. garvieae infection, and meanwhile, the significant decrease in haemolymph clotting times and respiratory bursts (RBs) per haemocyte of prawns were revealed. Furthermore, the mRNA expressions of prophenoloxidase (proPO), lipopolysaccharide and β-1,3-glucan binding protein (LGBP), peroxinectin (PE), transglutaminase (TG), and crustin (CT) were significantly increased. We therefore recommend that BPE can be used as an immunomodulator for prawns through dietary administration at 6.0 g kg(-1) for a long term (over 120 days) to modify immune responses and genes expression following the enhanced resistance against pathogens.

Impact of ammonia exposure on coagulation in white shrimp, Litopenaeus vannamei

Ammonia (un-ionized plus ionized ammonia as nitrogen), the end product of protein catabolism, is produced by decomposing organic matter. In aquaculture, shrimp are commonly exposed to high concentrations of ammonia that induces immunological and histological changes. The purpose of this study was to evaluate the effects on hemolymph coagulation time, transglutaminase (TG) activity as well as TG and clottable protein (CP) genes expressions in Litopenaeus vannamei when exposed to ambient ammonia-nitrogen (N) at 0, 1, 5, and 10mg/L for 0, 2, and 7 days. The actual concentrations in control and tests solution were 0.001, 1.15, 5.11, and 11.68mg/L for ammonia-N, and 7×10(-5), 0.080, 0.357, and 0.815mg/L for NH3-N (unionized ammonia). Delayed coagulation time following exposure to 5 and 10mg/L of ambient ammonia-N for 7 days, and increased transglutaminase (TG) activity following exposure to 5 and 1mg/L of ambient ammonia-N for 2 and 7 days, respectively, were observed. Downregulated TG expression and upregulated clottable protein (CP) expression in the hemocytes of L. vannamei exposed to 10 and 5mg/L of ambient ammonia-N for 2 and 7 days, respectively, were shown. These results indicated that ambient ammonia-N (>5mg/L) and NH3-N (>0.357mg/L) interrupted coagulation and down-regulated TG gene expression in L. vannamei, which caused ecotoxicity on immune deficiencies and may contribute the increased susceptibility to infection by pathogens.

Characterization and identification of calmodulin and calmodulin binding proteins in hemocyte of the black tiger shrimp (Penaeus monodon)

Calmodulin (CaM), a ubiquitous intracellular calcium (Ca(2+)) sensor in all eukaryotic cells, is one of the well-known signaling proteins. Previously, CaM gene has shown a high transcriptional level in hemocyte of the pathogen infected shrimp, suggesting that shrimp CaM does not only regulate Ca(2+) metabolism, but is also involved in immune response cascade. In the present study, the CaM gene of shrimp Penaeus monodon was identified and the recombinant P.monodon CaM (rPmCaM) was produced and biochemically characterized. The identification of CaM-binding proteins was also performed. The PmCaM cDNA consisted of an open reading frame of 447 bp encoding for 149 amino acid residues with a calculated mass of 16,810 Da and an isoelectric point of 4.09. Tissue distribution showed that the PmCaM transcript was expressed in all examined tissues. The results of gel mobility shift assay, circular dichroism spectroscopy and fluorescence spectroscopy all confirmed that the conformational changes of the rPmCaM were observed after the calcium binding. According to the gene silencing of PmCaM transcript levels, the shrimp's susceptibility to pathogenic Vibrio harveyi infection increased in comparison with that of the control groups. Protein pull-down assay and LC-MS/MS analysis were performed to identify rPmCaM-binding proteins involved in shrimp immune responses and transglutaminase, elongation factor 1-alpha, elongation factor 2 and actin were found. However, by computational analysis, only the first three proteins contained CaM-binding domain. These findings suggested that PmCaM may play an important role in regulation of shrimp immune system.

Dietary supplement of banana (Musa acuminata) peels hot-water extract to enhance the growth, anti-hypothermal stress, immunity and disease resistance of the giant freshwater prawn, Macrobrachium rosenbergii

In the present study, Macrobrachium rosenbergii were fed with diets containing extracts of banana, Musa acuminate, fruit's peel (banana peels extract, BPE) at 0, 1.0, 3.0 and 6.0 g kg(-1). The non-specific immune parameters, disease resistance and anti-hypothermal stress were evaluated at 2, 4, 8, 16 and 32 days of post feeding. Also, we demonstrated the percent weight gain (PWG), percent length gain (PLG), feeding efficiency (FE), and survival rate of giant freshwater prawn at 30, 60, 90, and 120 days of post feeding. The PWG, PLG, FE and survival rate of prawns fed at 0, 1.0, 3.0 and 6.0 g kg(-1) BPE-containing diets after 120 days were 69.5%, 75.4%, 77.8% and 83.3%; 21.8%, 23.6%, 27.8% and 33.9%; 0.60, 0.72, 0.75 and 0.90; and 55.4%, 62.2%, 62.3% and 75.3%, respectively. After 32 days of post feeding, a significant increase in total haemocyte count (THC), different haemocyte count (DHC), respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, phenoloxidase (PO) activity and transglutaminase (TG) activity, and meanwhile, a decreased haemolymph coagulation time was observed. Furthermore, phagocytic activity and clearance efficiency of prawns against Lactococcus garvieae infection were significantly increased. Prawns challenged with L. garvieae after 32 days of feeding at 1.0, 3.0 and 6.0 g kg(-1) had a significantly higher survival rate (33.3%, 40.0% and 56.7%) than those fed with the control diet. Subsequently, hypothermal (14 °C) stress was 43.4%, 50.0% and 50.0%, respectively. Altogether, we therefore recommend the dietary BPE administration at 6.0 g kg(-1) promotes growth, anti-hypothermal stress, and enhance immunity and resistance against L. garvieae in M. rosenbergii.

The second type of transglutaminase regulates immune and stress responses in white shrimp, Litopenaeus vannamei

The total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase activity, respiratory bursts (release of superoxide anion), superoxide dismutase activity, and phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were measured when white shrimp, Litopenaeus vannamei, (7.5 ± 0.5 g) were individually injected with diethyl pyrocarbonate-water (DEPC-H2O) or different dsRNA at 3 days of injection. In addition, haemolymph glucose and lactate, and haemocytes crustacean hyperglycemic hormone (CHH), transglutaminase I (TGI), transglutaminase II (TGII) and clottable protein (CP) mRNA expression were determined for the shrimp that received DEPC-H2O and different dsRNA after 3 days, and then transferred to 22 and 28 °C from 28 °C. Results showed that respiratory burst, phagocytic activity and clearance efficiency significantly decreased, but hyaline cells significantly increased in the shrimp received LvTGII dsRNA after 3 days. In hypothermal stress studies, LvTGI and CHH were significantly up-regulated in LvTGII-depleted shrimp following exposure to 28 and 22 °C, and haemolymph glucose and lactate were significantly enhanced in LvTGII-depleted shrimp. The injection of LvTGII dsRNA also significantly increased the mortality of L. vannamei challenged with the pathogen V. alginolyticus. These results suggest that LvTGII is an important component on the immune resistance of shrimp, and is involved in the regulation of some immune parameters and carbohydrate metabolites, as well as has a complementary effect with LvTGI in immunological and physiological response of shrimp.

Identification and cloning of the second type transglutaminase from Litopenaeus vannamei, and its transcription following pathogen infection and in relation to the haemolymph coagulation

Complementary (c)DNA encoding transglutaminaseII (TGII) messenger (m)RNA of white shrimp, Litopenaeus vannamei, was cloned from haemocytes by a reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) using oligonucleotide primers based on the TG sequence of the horseshoe crab, Tachypleus tridentatus (accession no.: BAA02134), tiger shrimp, Penaeus monodon (AAV49005; AAO33455), kuruma shrimp, Marsupenaeus japonicus (BAD36808) and Pacifastacus leniusculus (AAK69205) TG. The 2405-bp cDNA contained an open reading frame (ORF) of 2292 bp, a 31-bp 5'-untranslated region (UTR), and an 82-bp 3'-UTR containing a poly A tail. The molecular mass of the deduced amino acid (aa) sequence (764 aa) was 85.9 kDa with an estimated pI of 5.32. The L. vannamei TGII (abbreviated LvTGII) contains a typical TG-like homologue, two putative integrin binding motif (RGD and KGD), and five calcium-binding sites; three catalytic triad is present as in arthropod TG. Sequence comparison and phylogenetic analysis revealed that shrimp TG can be separated into two groups, STGI and STGII, and LvTGII is more closely related to STGII than to STGI. LvTGII mRNA was detected in all tested tissues of L. vannamei, and was highly expressed in haemocytes. The haemocytes of L. vannamei injected with Vibrio alginolyticus showed a significant increase of LvTGI and LvTGII mRNA expression at 6 h followed by a notable decrease at 24 h in LvTGI and a continually increase in LvTGII indicating a complementary effect, which implied that both LvTGs involved in the immune response of shrimp, and LvTGII was more important in the later defense response. The gene silencing of LvTGII in shrimp significantly decreased LvTGII expression and TG activity of haemocytes, and significantly increased clotting time of haemolymph, suggests that the cloned LvTGII is a clotting enzyme involved in haemolymph coagulation of L. vannamei. In conclusion, the cloned LvTGII is a clotting enzyme involved in coagulation of haemolymp and immune response of white shrimp, L. vannamei.

Effects of dietary administration of water hyacinth (Eichhornia crassipes) extracts on the immune responses and disease resistance of giant freshwater prawn, Macrobrachium rosenbergii

The hot-water extract of Eichhornia crassipes leaves (ECE) was produced and incorporated into the diet of the prawn, Macrobrachium rosenbergii, as an immunostimulant. Survival rates of prawn against Lactococcus garvieae, and its immune parameters including the total haemocyte count (THC), different haemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, transglutaminase (TG) activity, haemolymph coagulation time, and phagocytic activity and clearance efficiency against L. garvieae by M. rosenbergii were determined when prawn (23.0 ± 2.8 g) were fed ECE-containing diets at 0, 1.0, 2.0 and 3.0 g kg(-1). Prawn fed a diet containing ECE at 2.0 and 3.0 g kg(-1) for 12 days showed significantly increased THC, HC, GC, PO activity, RBs, SOD activity, GPx activity, and TG activity, and a significantly decreased coagulation time. The phagocytic activity and clearance efficiency against L. garvieae of prawn fed the ECE-containing diets at 1.0, 2.0, and 3.0 g kg(-1) were significantly higher than those of prawn fed the control diet at 3-12 days. Survival rates of M. rosenbergii fed the diet containing ECE at concentrations of 2 and 3 g kg(-1) were significantly higher than those fed the control diet after challenge with L. garvieae for 48-144 h. The relative percentage survival of prawn fed the 1.0, 2.0, and 3.0 g kg(-1) ECE-containing diets for 12 days were 17.5%, 39.1%, and 52.2%. It was concluded that the ECE can be used as an immunostimulant for prawn through dietary administration to enhance immune responses and resistance of M. rosenbergii against L. garvieae.

Molecular and immunological responses of the giant freshwater prawn, Macrobrachium rosenbergii, to the organophosphorus insecticide, trichlorfon

Trichlorfon is an organophosphorus (OP) insecticide that is used as an agriculture pesticide to destroy insects, a human medicine to combat internal parasites, and an ectoparasiticide in the livestock and aquaculture industries, but which has caused aquatic toxicity in the prawn industry. The aim of this study was to investigate the effects of trichlorfon on molecular and enzymatic processes of the immunological response of the giant freshwater prawn, Macrobrachium rosenbergii, at 0, 0.2, and 0.4mgL(-1) with 0, 3, 6, 12, and 24h of exposure. The total hemocyte count (THC), respiratory bursts (RBs), phenoloxidase (PO) activity, and superoxide dismutase (SOD) activity were examined to evaluate immunological responses and oxidative stress. Results showed that THCs of the prawn exposed to trichlorfon at both concentrations (0.2 and 0.4mgL(-1)) had increased after 12 and 24h; SOD and PO activities had significantly increased at 3h, whereas production of RBs had dramatically increased as oxidative stress at each sampling time after exposure to trichlorfon compared to the control. A potential biomarker of OPs, acetylcholinesterase (AChE) revealed a significant decrease after exposure for 6h, and showed a time-dependent tendency. Immune gene expressions, including prophenoloxidase (proPO), the lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP), peroxinectin (PE), α2-macroglubulin (α2M), transglutaminase (TG), and copper, zinc (Cu,Zn)-SOD, of prawns exposed to trichlorfon at 0, 0.2, and 0.4mgL(-1) for 0, 6, and 24h were further evaluated. Expressions of all of the immune genes significantly decreased when prawns were exposed to 0.4mgL(-1) trichlorfon for 24h, and among them, an increase in SOD expression was seen after exposure to 0.4mgL(-1) for 6h. Prawns exposed to trichlorfon within 24h exhibited the decrease of circulating hemocytes, and also the induction of oxidative stress, which caused subsequent damage to DNA formation of immune genes. From these results, we concluded that immunological responses and immune gene expressions of prawn exposed to trichlorfon at 0.4mgL(-1) for 24h were perturbed, thus causing a deficiency in immunity and subsequent increased susceptibility to pathogen infections.

Comparative proteomic identification of the hemocyte response to cold stress in white shrimp, Litopenaeus vannamei

To understand molecular responses of crustacean hemocytes to cold stress, flow cytometer analysis and two-dimensional electrophoresis proteomic approach were used to investigate altered proteins in hemocytes of Litopenaeus vannamei during cold stress treatment. Through flow cytometer analysis, 13°C for 24h post-cold stress was selected as the suitable temperature and condition for cold stress treatment. MALDI-TOF/TOF MS analysis revealed that 6 forms of 6 proteins were significantly up-regulated, including three enzymes (cystathionase, glyceraldehyde 3-phosphate dehydrogenase and glyoxalase 1) and one immune-related protein (oncoprotein nm23), whereas 24 forms of 3 proteins were significantly down-regulated in the treated shrimp (hemocyanin, hemocyte transglutaminase and transketolase). There were 20 spots identified as hemocyanin meaning that it may play important roles in environmental regulation in shrimp. Real-time fluorescence quantitative PCR confirmed that the levels of transcription of the hemocyanin, partial mRNA for hemocyanin, cystathionase, glyoxalase 1 and oncoprotein nm23 genes were found to relate well with that of their translation products after cold stress treated, while only the levels of hemocyte transglutaminase transcripts were not corresponded with that of their translation products. Further investigation of these data may lead to better understanding of the molecular responses of crustacean hemocytes to cold stress.