Two alpha-2 macroglobulin from Portunus trituberculatus involved in the prophenoloxidase system, phagocytosis and regulation of antimicrobial peptides

Comprehensive metabolomics and transcriptomics analyses investigating the regulatory effects of different sources of dietary astaxanthin on the antioxidant and immune functions of commercial-sized rainbow trout

Astaxanthin is an important aquatic feed additive that enhances the antioxidant capacity, and immune function of rainbow trout (Oncorhynchus mykiss); however, very limited information is available on its underlying molecular mechanisms. Haematococcus pluvialis powder, Phaffia rhodozyma powder, and synthetic astaxanthin were added to the commercial feed (no astaxanthin, NA) to prepare three experimental feeds, referred to as the HPA, PRA, and SA groups, respectively, and their actual astaxanthin contents were 31.25, 32.96, and 31.50 mg.kg-1, respectively. A 16-week feeding trial was conducted on the O. mykiss with an initial body weight of 669.88 ± 36.22 g. Serum and head kidney samples from commercial-sized O. mykiss were collected for metabolomics and transcriptomics analysis, respectively. Metabolomics analysis of the serum revealed a total of 85 differential metabolites between the astaxanthin-supplemented group and the control group. These metabolites were involved in more than 30 metabolic pathways, such as glycerophospholipid metabolism, fatty acid biosynthesis, linoleic acid metabolism, and arginine and proline metabolism. It is speculated that different sources of dietary astaxanthin may regulate antioxidant capacity and immunity mainly by affecting lipid metabolism and amino acid metabolism. Transcriptomic analysis of the head kidney revealed that the differentially expressed genes between the astaxanthin-supplemented group and the control group, such as integrin beta-1 (ITGB1), alpha-2-macroglobulin (A2M), diamine acetyltransferase 1 (SAT1), CCAAT/enhancer-binding protein beta (CEBPB) and DNA damage-inducible protein 45 alpha (GADD45A), which are involved in cell adhesion molecules, the FoxO signaling pathway, phagosomes, and arginine and proline metabolism and play regulatory roles in different stages of the antioxidant and immune response of O. mykiss.

Dragon fruit-derived oligosaccharides alter hemocyte-mediated immunity and expression of genes related to innate immunity and oxidative stress in Daphnia magna

Dragon fruit oligosaccharide (DFO) is an indigestible prebiotic that enhances the growth and reproduction of Daphnia magna, increases the expression of genes involved in immunity, and reduces oxidative stress. This study investigated the effects of DFO on the expression of innate immunity- (Toll, Pelle, proPO, A2M, and CTL), oxidative stress- (Mn-SOD), and nitric oxide (NO) synthesis-related genes (NOS1, NOS2, and arginase) as well as NO localization and number of hemocytes in D. magna. For this ten-day-old D. magna were treated with 0 or 9 mg l-1 of DFO for 24 and 85 h. Gene expression levels, NO intensity and localization, and total hemocytes were evaluated. After 24 h, the expression of Toll and proPO increased significantly (p < 0.05), while that of C-type lectins (CTL) was reduced (p < 0.05). At 85 h, Mn-SOD and CTL expressions were markedly suppressed (p < 0.05). NO was mostly localized in the foregut, midgut, hindgut, and carapace. The expression of NOS1 was reduced after 24 h (p < 0.05). In addition, NO intensity at 24 h was insignificantly lower than the control (p > 0.05). At 85 h, the expression of NOS1, NOS2, and arginase was higher than control, but NO intensity did not differ significantly (p > 0.05). Furthermore, the total hemocyte count elevated remarkably at 85 h (p < 0.05). Our study suggested that 9 mg l-1 of DFO could alter the expression of the genes related to innate immunity, oxidative stress, and NO synthesis in D. magna and significantly stimulate hemocyte production.

Comparative proteome analysis revealed potential biomarkers and the underlying immune mechanisms in Vibrio-resistant hybrid grouper, Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂

Vibrio alginolyticus is the causative agent of vibriosis, a common bacterial infection in grouper aquaculture that is associated with the development of haemorrhagic and non-haemorrhagic ulcerations on the fish. In the present study, comparative proteome analysis was performed on serum samples from Vibrio-resistant and Vibrio-susceptible grouper. Samples were analysed using high-throughput LC-MS/MS and identified 2770 unique peptides that corresponded to 344 proteins. Subsequent analysis identified 21 proteins that were significantly up-regulated in the resistant group compared to the control and the susceptible groups. Those proteins are associated with immunostimulatory effects, signalling and binding cascade, metabolism, and maintaining tissue integrity and physiological condition. Besides, potential protein biomarkers related to the immune system were identified, which could be associated with the disease-resistant phenotype. These data provide insights into the underlying immune mechanism of hybrid groupers upon Vibrio sp. infection.

Differential analysis of the haemolymph proteome of Carcinus maenas parasitized by Sacculina carcini (Cirripeda, Rhizocephala) reveals potential mechanisms of parasite control

Sacculina carcini is an endoparasite of the green crab, Carcinus maenas. This parasite induces behavioural changes in its host and affects its metabolism by inhibiting moulting and reproduction. Using a proteomic approach in mass spectrometry, we studied the haemolymph proteomes of healthy and parasitized wild green crabs from Brittany, France to identify proteins that are differentially expressed as a consequence of parasitization. We also investigated specific proteins involved in reproduction, moulting, and immunity. We detected 77 proteins for females and 53 proteins for males that were differentially present between the healthy and parasitized crabs, some of which were sex-specific. Detection of these differentially expressed proteins suggests that the parasite can inhibit and promote different aspects of the immune response of the host. Sacculina appears to inhibit host melanisation for self-protection, while promoting the presence of immune factors, such as antimicrobial peptides to cope with possible bacterial superinfections. Moreover, one protein, juvenile hormone esterase-like carboxylesterase, was 17-times more abundant in parasitized crabs than in healthy crabs and may be responsible for inhibiting moulting and reproduction in parasitized crabs, thus ensuring the success of Sacculina reproduction.

Proteomics of the haemolymph of the terrestrial crustacean Porcellio scaber reveals components of its innate immunity under baseline conditions

The terrestrial crustacean Porcellio scaber is an established test organism in environmental research. We analysed the haemolymph proteome of P. scaber using a classical proteomic approach based on one-dimensional gel electrophoresis and tandem mass spectrometry. Using a publicly available protein database and our P. scaber transcriptome data, we have identified 76 proteins involved in cytoskeleton formation, protein degradation, vesicular transport, genetic information processing, detoxification, carbohydrate and lipid metabolism reflecting haemocyte metabolic activity, active intracellular transport, and intercellular communication. Compared with the data reported for other crustaceans, 28 of these P. scaber proteins have been linked to its immunity, among them hemocyanin, α-2-macroglobulin, phenoloxidase 3, superoxide dismutase, glutathione S-transferase, haemolymph clottable protein, and histones H4 and H2B. Our results thus provide a firm base for studying the innate immune response of P. scaber at the level of the haemolymph proteome. This knowledge is of particular importance in ecotoxicity studies with various environmental stressors where understanding physiological changes is important to reveal possible modes of action.

Complement-related proteins in crustacean immunity

As an important part of innate immune system, complement system is widely involved in defense response and immune regulation, and plays an important biological role. The complement system has been deeply studied. More than 30 complement-related molecules and three major complement-activation pathways have been identified in vertebrates. Crustacean animals do not have complement system. There are only some complement-related proteins in crustaceans which are important for host defense. In this review, we summarize the current knowledge about complement-related proteins in crustaceans, and their functions in crustacean immunity. We also make a comparation of the crustacean pro-phenoloxidase activating system and the mammalian complement system. This review provides a better understanding of the evolution and function of complement-related proteins in crustaceans.

Transcriptomic profiling of immune-associated molecules in the coelomocytes of lugworm Arenicola marina (Linnaeus, 1758)

Organization and functioning of immune system remain unevenly studied in different taxa of lophotrochozoan animals. We analyzed transcriptomic data on coelomocytes of the lugworm Arenicola marina (Linnaeus, 1758; Annelida, Polychaeta) to gain insights into the molecular mechanisms involved in polychaete immunity. Coelomocytes are specialized motile cells populating coelomic fluid of annelids, responsible for cellular defense reactions and providing humoral immune factors. The transcriptome was enriched with immune-related transcripts by challenging the cells in vitro with lipopolysaccharides of Escherichia coli and Zymosan from Saccharomyces cerevisiae. Our analysis revealed a multifaceted and complex internal defense system of the lugworm. A. marina possesses orthologs of proto-complement-like factors: six thioester-containing proteins, a complement-like receptor, and a MASP-related serine protease (MReM2). A. marina coelomocytes employ pattern-recognition receptors to detect pathogens and regulate immune responses. Among them, there are 18 Toll-like receptors and various putative lectin-like proteins with evolutionary conserved and taxa-specific domains. C-type lectins and a novel family of Gal-binding and CUB domains containing receptors were the most abundant in the transcriptome. The array of pore-forming proteins in the coelomocytes was surprisingly reduced compared to that of other invertebrate species. We characterized a set of conserved proteins metabolizing reactive oxygen species and nitric oxide and expanded the arsenal of potential antimicrobial peptides. Phenoloxidase activity in immune cells of lugworm is mediated only by laccase enzyme. The described repertoire of immune-associated molecules provides valuable candidates for further functional and comparative research on the immunity of annelids.

Effects of berberine hydrochloride on immune response in the crab Charybdis japonica

Berberine hydrochloride is the main effective component of Coptis spp. used in Chinese herbal medicine and its underlying molecular mechanisms, responsible for inducing effects in crustacean species, are not fully understood. In this study, the molecular response of the crab Charybdis japonica to berberine hydrochloride exposure was studied using transcriptome sequencing. The survival rate, gene expression and activities of several immune enzymes were measured after berberine hydrochloride treatments, with or without injection of the pathogenic bacterium Aeromonas hydrophila. A total of 962 differentially expressed genes (464 up-regulated and 498 down-regulated) were observed during exposure to 100 mg/L of berberine hydrochloride and in the control group after 48 h. Enrichment analysis revealed that these genes are involved in metabolism, cellular processes, signal transduction and immune functions, indicating that exposure to berberine hydrochloride activated the immune complement system. This bioactive compound simultaneously activated fibrinogen beta (FGB), fibrinogen alpha (FGA), alpha-2-macroglobulin (A2M), kininogen (KNG), fibrinogen gamma chain (FGB), alpha-2-HS-glycoprotein (AHSG), caspase-8 (CASP8), cathepsin L (CTSL), adenylate cyclase 3 (Adcy3) and MMP1. Its action could significantly increase the survival rate of the crabs injected with A. hydrophila and promote the activity of LZM, Caspas8, FGA, ACP and AKP in the hepatopancreas. When A. hydrophila was added, the neutralization of 300 mg/L berberine hydrochloride maximized the activities of Caspas8, LZM, ACP and AKP. Our results provide a new understanding of the potential effects of berberine hydrochloride on the immune system mechanisms in crustaceans.

iTRAQ and PRM-based comparative proteomic profiling in gills of white shrimp Litopenaeus vannamei under copper stress

Crustaceans are particularly sensitive to heavy metal pollution. Copper (Cu) is one of typical heavy metal pollutants in aquatic ecosystems. However, limited attention has been paid on the proteomic responses of shrimp under Cu stress. White shrimp Litopenaeus vannamei held in 5‰ seawater were exposed to 5 mg L^-1 Cu for 3 h, and the regulatory mechanism in the gills was elucidated using iTRAQ-based quantitative proteomics. The results showed that a total of 5034 proteins were identified, 385 differentially expressed proteins (DEPs), including 147 differentially up-regulated proteins (DUPs) and 238 differentially down-regulated proteins (DDPs) were found. Bioinformatics analysis indicated the DEPs responding to Cu stress mainly involved in cytoskeleton, immune response, stress response, protein synthesis, detoxification, ion homeostasis and apoptosis. Furthermore, we still performed PRM analysis on sarcoplasmic calcium binding protein (SCP), serine proteinase inhibitor B3 (SPIB3), C-type lectin 4 (CTL4), cathepsin L (CATHL), JHE-like carboxylesterase 1 (CXE1) and paramyosin (PMY), and biochemical analysis on Cu/Zn-superoxide dismutase (Cu/Zn-SOD) to validate the iTRAQ results, respectively. The present proteome analysis revealed that Cu stress disrupted the ion homeostasis and protein synthesis, and L.vannamei mainly regulates a series of molecular pathways which contained many key proteins involved in the immune process to protect the organism from Cu stress. Our data provides more insight about the underlying mechanisms that related to the stress response of Cu exposure in crustacean.

Cloning and characterization of chst11 from Procambarus clarkii involved in the host immune response of white spot syndrome virus and Aeromonas hydrophila

Carbohydrate sulfotransferases 11 (chst11) is one of the enzymes that synthesize chondroitin sulfate (CS), which has extensive immune functions in vitro and plays a critical role in mediating the infection of host by pathogenic microorganisms. However, whether it has immune functions in crayfish is still poorly understood. In our previous study of transcriptome, chst11 was differentially expressed in susceptible individuals and resistant individuals of Procambarus clarkii after white spot syndrome virus (WSSV) injection. Thus, in this study, the sequence of chst11 was obtained from P. clarkii for the first time and analyzed, and the expression pattern of chst11 was investigated. Besides, the purified recombinant protein of chst11 effect in protection in WSSV infection was explored. The full length of chst11 was 1536 bp with an 831-bp open reading frame (ORF), which encoding 276 amino acids residues with a calculated molecular mass of 33.1 kDa. The chst11 contains a Sulfotransfer_2 domain, one N-glycosylation site and three O-glycosylation sites. Phylogenetic analysis results showed that chst11 had the highest similarity to Penaeus vannamei (79.93%). The expression pattern of chst11 in different tissues indicated that chst11 was expressed highest in gut, gill and hypodermis, lowest in testicular duct, periesophageal nerve and hemocytes. The chst11 had different expression patterns in different tissues when the crayfish was challenged by WSSV, Aeromonas hydrophila and CpG ODN. Recombinant chst11 protein significantly reduced the amount of WSSV copy number in hepatopancreas at 6 h and 12 h post injection compared to the control group injected with bovine serum albumin (BSA). It was found that chst11 protein enhanced the expression of peroxinectin, proPO in hepatopancreas and midgut and the C-type lectin (ctl) in hemocytes and hepatopancreas. Intramuscularly injection of juvenile crayfish with chst11 protein decreased 60% mortality compared to the control group with BSA. This study is the first report on the antiviral function of chst11 in the immune system of crustacean.