Molecular cloning and characterization of two isoforms of cyclophilin A gene from Venerupis philippinarum

Antiviral properties of Penaeus monodon cyclophilin A in response to white spot syndrome virus infection in the black tiger shrimp

Cyclophilin A (CypA) or peptidylprolyl isomerase A, plays an important role in protein folding, trafficking, environmental stress, cell signaling and apoptosis etc. In shrimp, the mRNA expression level of PmCypA was stimulated by LPS. In this study, all three types of shrimp hemocytes: hyaline cell, granulocyte and semi-granulocyte expressed the PmCypA protein. The mRNA expression level of PmCypA was found to be up-regulate to four-fold in white spot syndrome virus (WSSV) infected hemocytes at 48 h. Interestingly, PmCypA protein was only detected extracellularly in shrimp plasma at 24 h post WSSV infection. To find out the function of extracellular PmCypA, the recombinant PmCypA (rPmCypA) was produced and administrated in shrimp primary hemocyte cell culture to observe the antiviral properties. In rPmCypA-administrated hemocyte cell culture, the mRNA transcripts of WSSV intermediate early gene, ie1 and early gene, wsv477 were significantly decreased but not that of late gene, vp28. To explore the antiviral mechanism of PmCypA, the expression of PmCypA in shrimp hemocytes was silenced and the expression of immune-related genes were investigated. Surprisingly, the suppression of PmCypA affected other gene expression, decreasing of penaeidin, PmHHAP and PmCaspase and increasing of C-type lectin. Our results suggested that the PmCypA might plays important role in anti-WSSV via apoptosis pathway. Further studies of PmCypA underlying antiviral mechanism are underway to show its biological function in shrimp immunity.

A Novel Disease (Water Bubble Disease) of the Giant Freshwater Prawn Macrobrachium rosenbergii Caused by Citrobacter freundii: Antibiotic Treatment and Effects on the Antioxidant Enzyme Activity and Immune Responses

The giant freshwater prawn, Macrobrachium rosenbergii, is an important and economical aquaculture species widely farmed in tropical and subtropical areas of the world. A new disease, "water bubble disease (WBD)", has emerged and resulted in a large loss of M. rosenbergii cultured in China. A water bubble with a diameter of about 7 mm under the carapace represents the main clinical sign of diseased prawns. In the present study, Citrobacter freundii was isolated and identified from the water bubble. The optimum temperature, pH, and salinity of the C. freundii were 32 °C, 6, and 1%, respectively. A challenging experiment showed that C. freundii caused the same typical signs of WBD in prawns. Median lethal dose of the C. freundii to prawn was 104.94 CFU/g. According to the antibiogram tests of C. freundii, florfenicol and ofloxacin were selected to evaluate their therapeutic effects against C. freundii in prawn. After the challenge with C. freundii, 86.67% and 72.22% survival of protective effects against C. freundii were evaluated in the oral florfenicol pellets and oral ofloxacin pellets feding prawns, respectively, whereas the mortality of prawns without fed antibiotics was 93%. After antibiotic treatment and C. freundii infection, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), malondialdehyde (MDA), acid phosphatase (ACP), alkaline phosphatase (ALP), and lysozyme (LZM) in the hemolymph and hepatopancreas of the prawns and the immune-related gene expression levels of Cu/Zn-SOD, CAT, GPx, GST, LZM, ACP, anti-lipopolysaccharide factor, crustin, cyclophilin A, and C-type lectin in hepatopancreas were all significantly changed, indicating that innate immune responses were induced by C. freundii. These results can be beneficial for the prevention and control of C. freundii in prawns.

Effects of dietary carbohydrate/lipid ratios on non-specific immune responses, antioxidant capacity, hepatopancreas and intestines histology, and expression of TLR-MAPK/NF-κB signaling pathway-related genes of Procambarus clarkii

To investigate the effects of dietary carbohydrate/lipid (CHO: L) ratios on non-specific immune responses, antioxidant capacity, and expression of TLR-MAPK/NF-κB signaling pathway-related genes of red swamp crayfish (Procambarus clarkii). Four isonitrogenous and isoenergetic diets containing different CHO: L ratios were formulated. The results showed that the group with a CHO: L ratio of 5.94 had better growth performance (P < 0.05). The highest T-AOC, CAT, and SOD activities and the lowest MDA content in hemolymph and hepatopancreas were observed in the group with a CHO: L ratio of 5.94 (P < 0.05). The lowest activities of ALT, AST, ACP, AKP, and ALB in the hemolymph were observed in CHO: L ratio 5.94 group (P < 0.05), while the highest LZM activity, TP, and GLB content were observed in CHO: L 5.94 group (P < 0.05). The highest mRNA expression levels of tlr3, myd88, and mapk3, and the lowest mRNA expression levels of nf-kb α, nf-kb β, nf-kb p105, and traf6 were observed in the CHO: L of 5.94 group (P < 0.05). The highest mRNA expression levels of immune-related genes were observed in the CHO: L of 5.94 group (P < 0.05). Overall, these results indicated that the optimum dietary CHO: L ratio is vital in promoting growth and enhancing antioxidants and immunity to maintain red swamp crayfish's intestinal and hepatopancreas health status. In conclusion, the diets with a CHO:L ratio of 5.94 (approximately 36.23% carbohydrate and 6.10% lipid) is optimal for juvenile red swamp crayfish's physiological condition and health status.

Long-lasting effects of chronic exposure to chemical pollution on the hologenome of the Manila clam

Chronic exposure to pollutants affects natural populations, creating specific molecular and biochemical signatures. In the present study, we tested the hypothesis that chronic exposure to pollutants might have substantial effects on the Manila clam hologenome long after removal from contaminated sites. To reach this goal, a highly integrative approach was implemented, combining transcriptome, genetic and microbiota analyses with the evaluation of biochemical and histological profiles of the edible Manila clam Ruditapes philippinarum, as it was transplanted for 6 months from the polluted area of Porto Marghera (PM) to the clean area of Chioggia (Venice lagoon, Italy). One month post-transplantation, PM clams showed several modifications to its resident microbiota, including an overrepresentation of the opportunistic pathogen Arcobacter spp. This may be related to the upregulation of several immune genes in the PM clams, potentially representing a host response to the increased abundance of deleterious bacteria. Six months after transplantation, PM clams demonstrated a lower ability to respond to environmental/physiological stressors related to the summer season, and the hepatopancreas-associated microbiota still showed different compositions among PM and CH clams. This study confirms that different stressors have predictable effects in clams at different biological levels and demonstrates that chronic exposure to pollutants leads to long-lasting effects on the animal hologenome. In addition, no genetic differentiation between samples from the two areas was detected, confirming that PM and CH clams belong to a single population. Overall, the obtained responses were largely reversible and potentially related to phenotypic plasticity rather than genetic adaptation. The results here presented will be functional for the assessment of the environmental risk imposed by chemicals on an economically important bivalve species.

The feeding of dietary Codonopsis pilosula polysaccharide enhances the immune responses, the expression of immune-related genes and the growth performance of red swamp crayfish (Procambarus clarkii)

Polysaccharides have many functions in aquatic animals and are widely used as immunopotentiators. However, despite the emergence of serious diseases, few studies have explored the effects of Codonopsis pilosula polysaccharide (CPP) on crustaceans. We studied the effects of CPP on the growth performance, nonspecific immunity, antioxidant activity and disease resistance of red swamp crayfish (Procambarus clarkii). Healthy crayfish (5.80 ± 0.1 g) were fed diets supplemented with 0% (control), 0.05%, 0.1%, 0.15%, 0.20%, and 0.30% CPP for 8 weeks. At the end of the 8-week feeding trial, the optimal final body weight (FBW), weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR) were observed in the crayfish fed the diets with 0.15% and 0.20% CPP, followed by those fed the diet with 0.30% CPP and then those fed the diet with 0.10% CPP, whereas the values of these parameters were obtained with the control crayfish (P < 0.05). The crayfish fed the diets with 0.15% and 0.20% CPP exhibited a significantly higher total hemocyte count (THC) and significantly increased phenoloxidase (PO), lysozyme (LZM), hemocyte (Hc), acid phosphatase (ACP) and alkaline phosphatase (AKP) compared with those belonging to the other groups (P < 0.05). The crayfish fed the diets with 0.15% and 0.2% CPP exhibited significantly higher total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) activities, a significantly increased total antioxidant capacity (T-AOC) and a significantly lower malondialdehyde (MDA) content compared with the other groups (P < 0.05), which indicated that antioxidant capacity was significantly induced by the CPP-supplemented diets. Significantly upregulated expression of immune-related genes (anti-lipopolysaccharide factors (alf), peroxiredoxin (prx5), cathepsin B (ctsb), mitochondrial manganese superoxide dismutase (mtMnsod), cyclophilin A (cypa), glutathione peroxidase (gpx), Toll-like receptor 3 (tlr3), and heat shock protein 70 (hsp70)) was detected in the crayfish fed the diets supplemented with 0.15% and 0.20% CPP diet compared with the levels observed in the control crayfish. These results showed that dietary CPP supplementation greatly improved the growth, immunity and antioxidant capacities of crayfish, and according to the observed results, 0.15%-0.2% is the recommended optimal level of CPP dietary supplementation for crayfish.

Effects of hesperidin on the growth performance, antioxidant capacity, immune responses and disease resistance of red swamp crayfish (Procambarus clarkii)

We evaluated the effects of hesperidin on the nonspecific immunity, antioxidant capacity and growth performance of red swamp crayfish (Procambarus clarkii). A total of 900 healthy crayfish were randomly divided into six groups: the control group (fed the basal diet) and the HES25, HES50, HES75, HES100 and HES150 groups, which were fed the basal diet supplemented with 25, 50, 75, 100 and 150 mg kg^-1 hesperidin, respectively. The feeding experiment lasted 8 weeks. The results indicated that compared with the control group, the crayfish groups supplemented with 50-150 mg kg^-1 hesperidin had a decreased feed conversion ratio (FCR) and increased final body weight (FBW), specific growth rate (SGR) and weight gain (WG) (P < 0.05). The protein carbonyl content (PCC), reactive oxygen species (ROS) level and malondialdehyde (MDA) level in the hepatopancreas and hemocytes were significantly lower, while the total antioxidant capacity (T-AOC), glutathione peroxidase (GPx) activity, and superoxide dismutase (SOD) activity were significantly higher in the crayfish groups supplemented with 50-150 mg kg^-1 hesperidin than in the control group. Supplementation with 50-150 mg kg^-1 hesperidin significantly increased the activities of acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM), and phenoloxidase (PO) compared with the control group (P < 0.05); upregulated the mRNA expression of cyclophilin A (CypA), extracellular copper-zinc superoxide dismutase (ecCuZnSOD), GPxs, crustin, astacidin, Toll3 and heat shock protein 70 (HSP70) (P < 0.05); and decreased crayfish mortality following white spot syndrome virus (WSSV) infection. These findings indicate that dietary hesperidin supplementation at an optimum dose of 50-150 mg kg^-1 may effectively improve nonspecific immunity, antioxidant capacity and growth performance in crayfish.

Transcriptomic analysis of clam extrapallial fluids reveals immunity and cytoskeleton alterations in the first week of Brown Ring Disease development

The Brown Ring Disease is an infection caused by the bacterium Vibrio tapetis on the Manila clam Ruditapes philippinarum. The process of infection, in the extrapallial fluids (EPFs) of clams, involves alteration of immune functions, in particular on hemocytes which are the cells responsible of phagocytosis. Disorganization of the actin-cytoskeleton in infected clams is a part of what leads to this alteration. This study is the first transcriptomic approach based on collection of extrapallial fluids on living animals experimentally infected by V. tapetis. We performed differential gene expression analysis of EPFs in two experimental treatments (healthy-against infected-clams by V. tapetis), and showed the deregulation of 135 genes. In infected clams, a downregulation of transcripts implied in immune functions (lysosomal activity and complement- and lectin-dependent PRR pathways) was observed during infection. We also showed a deregulation of transcripts encoding proteins involved in the actin cytoskeleton organization such as an overexpression of β12-Thymosin (which is an actin sequestration protein) or a downregulation of proteins that closely interact with capping proteins such as Coactosin, that counteract action of capping proteins, or Profilin. We validated these transcriptomic results by cellular physiological analyses that showed a decrease of the lysosome amounts and the disorganization of actin cytoskeleton in infected hemocytes.

Gene expression and genotoxicity in Manila clam (Ruditapes philippinarum) modulated by sediment contamination and lagoon dynamics in the Po river delta

The lagoons of the Po River delta are potentially exposed to complex mixtures of contaminants, nevertheless, there is a substantial lack of information about the biological effects of these contaminants in the Po delta lagoons. These environments are highly dynamic and the interactions between chemical and environmental stressors could prevent the proper identification of biological effects and their causes. In this study, we aimed to disentangle such interactions focusing on Manila clams, previously exposed to six lagoons of the Po delta, adopting three complementary tools: a) the detailed description via modelling techniques of lagoon dynamics for salinity and water temperature; b) the response sensitivity of a number of target genes (ahr, cyp4, ρ-gst, σ-gst, hsp22, hsp70, hsp90, ikb, dbh, ach, cat, Mn-sod, Cu/Zn-sod, cyp-a, flp, grx, TrxP) investigated in clam digestive glands by Real Time PCR; and c) the relevance of DNA adducts determined in clams as markers of exposure to genotoxic chemicals. The lagoons showed specific dynamics, and two of them (Marinetta and Canarin) could induce osmotic stress. A group of genes (ahr, cyp4, Mn-sod, σ-gst, hsp-22, cyp-a, TrxP) seemed to be associated with overall lagoon characteristics as may be described by salinity and its variations. Lagoon modelling and a second group of genes (hsp70, hsp90, cat, ikb, ach, grx, Cu/Zn-sod) also suggested that moderate increases of river discharge may imply worse exposure conditions. Oxidative stress seemed to be associated with such events but it was slightly evident also under normal exposure conditions. DNA adduct formation was mainly associated with overwhelmed antioxidant defences (e.g. low Cu/Zn-sod) or seemingly with their lack of response in due time. In Po delta lagoons, Manila clam can be affected by chemical and environmental factors which can contribute to induce oxidative stress, DNA adduct formation and, ultimately, to affect clam condition and health.

Molecular identification and expression analysis of a novel cyclophilin a gene in the red swamp crayfish, Procambarus clarkii

Cyclophilin A (Cyp A) is the main intracellular receptor of cyclosporin A (CsA) belonging to the immunophilin family, which is known as an effective immunosuppressive drug. This study aimed to gain insights into the structure and biological function of cyclophilin A in the red swamp crayfish, Procambarus clarkii (PcCypA). We cloned PcCypA by homology cloning and anchored polymerase chain reaction (PCR), and assessed its mRNA and protein expression levels in different tissues using quantitative real-time PCR and western blot analysis, respectively. The full-length DNA contained a 5' untranslated region (UTR) comprising 108 base pairs (bp), an open reading frame of 495 bp encoding a polypeptide of 164 amino acids with an estimated molecular mass of 17.3 kDa, and a 3' UTR of 281 bp including a significant poly(A) plus tail sequence. The predicted amino acid sequence of PcCypA shared high identity with CypA in other organisms. PcCypA transcripts were detected in the hepatopancreas, gill, heart, muscle, testis, and ovary of crayfish, with the highest expression levels in the heart. Western blot analysis found one 17-kDa band in all of the tissues examined, except for the ovary. Molecular identification and expression analysis of PcCypA will facilitate further studies of the immune defense mechanisms in red swamp crayfish, and provide new insights into freshwater invertebrate immunology.

Characterization of cyclophilin D in freshwater pearl mussel (Hyriopsis schlegelii)

Cyclophilin D (referred to as HsCypD) was obtained from the freshwater pearl mussel (Hyriopsis schlegelii). The full-length cDNA was 2 671 bp, encoding a protein consisting of 367 amino acids. HsCypD was determined to be a hydrophilic intracellular protein with 10 phosphorylation sites and four tetratricopeptide repeat (TPR) domains, but no signal peptide. The core sequence region YKGCIFHRIIKDFMVQGG is highly conserved in vertebrates and invertebrates. Phylogenetic tree analysis indicated that CypD from all species had a common origin, and HsCypD had the closest phylogenetic relationship with CypD from Lottia gigantea. The constitutive mRNA expression levels of HsCypD exhibited tissue-specific patterns, with the highest level detected in the intestines, followed by the gonads, and the lowest expression found in the hemocytes.

Comparative proteomic analysis of two clam species: Chamelea gallina and Tapes philippinarum

Clams have long been a fisheries and aquaculture sector of great importance in Italy, the main resource of fisheries is the Chamelea gallina of indigenous origin, whereas clams breeding is supported almost entirely by the Tapes philippinarum, a species of Indo-Pacific origin. Bivalve molluscs quality depends mainly on the water quality, and then by a series of factors such as water temperature and salinity, gametogenic cycle, food availability, and environmental conditions, that affect the Condition Index. In this work crude extracts obtained from the edible part of Chamelea gallina and Tapes philippinarum were analyzed by a proteomic approach based on a two-dimensional gel electrophoresis followed by liquid chromatography-tandem mass spectrometry, in order to detect biomarkers useful for identification of the two kinds of clams and to assess their nutritional characteristics. As a result, four differentially expressed spots were found and identified, namely enolase, cyclophilin-A, ribosomal protein L13 and actin-1.

Chemotactic Activity of Cyclophilin A in the Skin Mucus of Yellow Catfish (Pelteobagrus fulvidraco) and Its Active Site for Chemotaxis

Fish skin mucus is a dynamic barrier for invading pathogens with a variety of anti-microbial enzymes, including cyclophilin A (CypA), a multi-functional protein with peptidyl-prolyl cis/trans isomerase (PPIase) activity. Beside various other immunological functions, CypA induces leucocytes migration in vitro in teleost. In the current study, we have discovered several novel immune-relevant proteins in yellow catfish skin mucus by mass spectrometry (MS). The CypA present among them was further detected by Western blot. Moreover, the CypA present in the skin mucus displayed strong chemotactic activity for yellow catfish leucocytes. Interestingly, asparagine (like arginine in mammals) at position 69 was the critical site in yellow catfish CypA involved in leucocyte attraction. These novel efforts do not only highlight the enzymatic texture of skin mucus, but signify CypA to be targeted for anti-inflammatory therapeutics.

First characterization of three cyclophilin family proteins in the oyster, Crassostrea ariakensis Gould

Cyclophilins (CyPs) are a family of proteins that bind the immunosuppressive agent cyclosporin A (CsA) with high-affinity and belong to one of the three superfamilies of peptidyl-prolyl cis-trans isomerases (PPIase). In this report, three cyclophilin genes (Ca-CyPs), including Ca-CyPA, Ca-CyPB and Ca-PPIL3, were identified from oyster, Crassostrea ariakensis Gould in which Ca-CyPA encodes a protein with 165 amino acid sequences, Ca-CyPB encodes a protein with 217 amino acid sequences and Ca-PPIL3 encodes a protein with 162 amino acid sequences. All of the three Ca-CyPs genes contain a typical CyP-PPIase domain with its signature sequences and Ca-CyPB contains an N-signal peptide sequences. Tissue distribution study revealed that Ca-CyPs were ubiquitously expressed in all examined tissues and the highest levels were observed in hemocytes. RLO incubation upregulated the mRNA expression levels of Ca-CyPs, indicating that three Ca-CyPs might be involved in oyster immune response against RLO infection.

Molecular cloning and functional characterization of cyclophilin A in yellow catfish (Pelteobagrus fulvidraco)

Cyclophilin A (CypA) is a ubiquitously expressed protein which involves in diverse pathological conditions including infection and inflammation. In this report, a CypA gene (designated as YC-CypA) was cloned from yellow catfish (Pelteobagrus fulvidraco) which is an important cultured fish species in Asian countries. The open reading frame (ORF) of YC-CypA encoded a polypeptide of 164 amino acids with calculated molecular weight of 17.70 kDa. The deduced amino acid sequences of the YC-CypA shared highly conserved structures with CypAs from the other species, indicating that YC-CypA should be a new member of the CypA family. Full-length YC-CypA protein was expressed in Escherichia coli and specific polyclonal antibody against YC-CypA was generated. The YC-CypA protein showed chemotactic activity by transwell migration assay. The mRNA and protein of YC-CypA could be detected in all examined tissues with relatively higher mRNA level in spleen and higher protein level in head kidney, respectively. The temporal expression patterns of YC-CypA, IL-1β and TNF-α mRNAs were analyzed in the liver, spleen and head kidney post of Edwardsiella ictaluri infection. By immunohistochemistry assay, slight enhancement of YC-CypA protein was observed in the liver, spleen, body kidney and head kidney of yellow catfish infected with E. ictaluri. In conclusion, YC-CypA of yellow catfish showed chemotactic activity in vitro and might have been involved in cytokines secretion in yellow catfish during the infection of E. ictaluri.

Identification of differentially expressed genes in the digestive gland of manila clam Ruditapes philippinarum exposed to BDE-47

Suppression subtractive hybridization (SSH) was used to identify alterations in gene transcription of the manila clam Ruditapes philippinarum after exposure to 5μg/L 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) for 15days. The ability to accumulate BDE-47 in digestive gland and gill was also evaluated in order to provide information for food safety. Analysis of tissue extracts indicated that digestive gland had the higher BDE-47 levels (12,463.1±1334.8 ng/g d.w.) compared to gill (6368.6±738.7ng/g d.w.) after a 15-day exposure period. Forward and reverse SSH libraries were made from pooled digestive glands of R. philippinarum, from which 75 high quality sequences were obtained by BLAST analysis. The expression of 39 genes with significant homology (E-value<10(-5)) out of the 75 sequences was investigated by quantitative RT-PCR. Among the 39 genes, 27 genes were found up-regulated while 12 genes were found down-regulated after the BDE-47 exposure. The 39 genes were involved in cellular cycle, cytoskeleton, substance and energy metabolism, stress response, innate immunity and cell signaling and transport which were extensively discussed. This study provides a preliminary basis for studying the response of marine bivalves upon exposure to PBDEs in terms of regulated gene expression.

cDNA cloning and mRNA expression of four glutathione S-transferase (GST) genes from Mytilus galloprovincialis

Glutathione S-transferases (GSTs) are phase II enzymes involved in the regulation of redox homeostasis and innate immune responses against bacterial infection, which also play important roles in the detoxification of xenobiotics. In this study, we reported four genes of the GST family (named MgGSTα, MgGSTS1, MgGSTS2, and MgGSTS3, respectively) from Mytilus galloprovincialis. MgGSTα, MgGSTS1, MgGSTS2, and MgGSTS3 consisted of open reading frame (ORF) of 648 bp, 612 bp, 621 bp and 609 bp respectively, which encoded proteins of 216, 204, 207 and 203 amino acids residues, respectively. Sequence analysis showed that the predicted protein sequence of MgGSTs contained the conserved domain of the GST_N and GST_C. Alignment analysis indicated that the MgGSTs were divided into two types, one was of alpha GST, and the others were of sigma class. Tissue distribution study revealed that MgGSTα, MgGSTS2, MgGSTS3 transcripts were highly expressed in hemocytes, while MgGSTS1 mRNA was most abundantly expressed in hepatopancreas. After bacterial challenge, the expression level of these MgGSTs in hemocytes were all significantly higher than that of the control group. These results suggested that MgGSTs might play important roles in the modulation of immune response in M. galloprovincialis.