Molecular characterization of the sarcoplasmic calcium-binding protein (SCP) from crayfish Procambarus clarkii

Ecotoxicological impact of heavy metals on wild mud crabs (Scylla olivacea) in Malaysia: An integrative approach of omics, molecular docking and human risk assessment

Mud crab, one of the aquatic organisms found in estuary areas, has become a significant economic source of seafood for communities due to its delectable taste. However, they face the threat of heavy metal contamination, which may adversely affect their biological traits. This study explored the comparison of the mud crabs collected from Setiu Wetland as a reference site, while Kuala Sepetang is an area that contains a higher concentration of heavy metals than Setiu Wetlands. Heavy metal levels were quantified using inductively coupled plasma mass spectrometry (ICP-MS), while proteomes were assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 1H nuclear magnetic resonance (NMR)-based metabolomics, respectively. Heavy metal contamination affects the proteome, metabolome, and putative molecular targets in mud crabs (Scylla olivacea), leading to oxidative stress. Mud crabs collected from the metal-polluted area of Kuala Sepetang in Perak had considerably elevated concentrations of nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), and cadmium (Cd) in comparison to the reference site of Setiu Wetlands in Terengganu. The proteome analysis revealed an upregulation of the stress-response protein Hsp70, which triggered superoxide dismutase (SOD) and increased arginine kinase expression (5.47 fold) in the muscle tissue, results in the alteration of metabolite regulation in the mud crab from Kuala Sepetang. Additionally, in the muscle tissues of mud crabs obtained from Kuala Sepetang, uncharacterized myosin-tail 1 domain proteins and sarcoplasmic calcium-binding proteins were downregulated. The metabolomic investigation identified changes in metabolites associated with energy metabolism and osmoregulation. Exploration of docking analysis suggests potential connections between methylarsonic acid and essential proteins in mud crabs. These findings suggest that the presence of heavy metals disrupts physiological processes and highlights potential molecular targets that warrant further investigation.

A comprehensive review on glycation and its potential application to reduce food allergenicity

Food allergens are a major concern for individuals who are susceptible to food allergies and may experience various health issues due to allergens in their food. Most allergenic foods are subjected to heat treatment before being consumed. However, thermal processing and prolonged storage can cause glycation reactions to occur in food. The glycation reaction is a common processing method requiring no special chemicals or equipment. It may affect the allergenicity of proteins by altering the structure of the epitope, revealing hidden epitopes, concealing linear epitopes, or creating new ones. Changes in food allergenicity following glycation processing depend on several factors, including the allergen's characteristics, processing parameters, and matrix, and are therefore hard to predict. This review examines how glycation reactions affect the allergenicity of different allergen groups in allergenic foods.

Immunological comparison of recombinant shrimp allergen Pen m 4, produced in Pichia pastoris and Escherichia coli

Shellfish are a leading cause of allergies worldwide, affecting about one-tenth of the general population. The sarcoplasmic calcium-binding protein, also known as allergen Pen m 4, is an important factor in shrimp allergies. Our objective was to assess the most effective techniques for producing a recombinant Pen m 4 protein as a potential tool for diagnosing shrimp allergies. In this study, for the first time, we produced a functional recombinant Pen m 4 protein in a eukaryotic system, Pichia pastoris, and analyzed it against Escherichia coli-produced equivalents in enzyme-linked immunosorbent and reverse-phase protein microarray assays. A dual tag system based on the maltose-binding protein was successfully used to increase the yield of Pen m 4 by 1.3 to 2.3-fold in both bacteria and yeast, respectively. Immunological characterization showed that N-glycosylation is neither crucial for the folding of Pen m 4 nor its recognition by specific IgE. However, the Ca²⁺-depletion assay indicated a dependence on calcium ion presence in blood samples. Results demonstrate how a comparative analysis can elucidate essential allergen manufacturing points. In conclusion, E. coli-produced Pen m 4 protein fused with the maltose-binding protein should be the preferred option for further studies in Penaeus monodon allergy diagnostics.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Transcriptomic Changes Following Induced De-Masculinisation of Australian Red Claw Crayfish Cherax quadricarinatus

The Australian red claw crayfish Cherax quadricarinatus, an emerging species within the freshwater aquaculture trade, is not only an ideal species for commercial production due to its high fecundity, fast growth, and physiological robustness but also notoriously invasive. Investigating the reproductive axis of this species has been of great interest to farmers, geneticists, and conservationists alike for many decades; however, aside from the characterisation of the key masculinising insulin-like androgenic gland hormone (IAG) produced by the male-specific androgenic gland (AG), little remains known about this system and the downstream signalling cascade involved. This investigation used RNA interference to silence IAG in adult intersex C. quadricarinatus (Cq-IAG), known to be functionally male but genotypically female, successfully inducing sexual redifferentiation in all individuals. To investigate the downstream effects of Cq-IAG knockdown, a comprehensive transcriptomic library was constructed, comprised of three tissues within the male reproductive axis. Several factors known to be involved in the IAG signal transduction pathway, including a receptor, binding factor, and additional insulin-like peptide, were found to not be differentially expressed in response to Cq-IAG silencing, suggesting that the phenotypic changes observed may have occurred through post-transcriptional modifications. Many downstream factors displayed differential expression on a transcriptomic level, most notably related to stress, cell repair, apoptosis, and cell proliferation. These results suggest that IAG is required for sperm maturation, with necrosis of arrested tissue occurring in its absence. These results and the construction of a transcriptomic library for this species will inform future research involving reproductive pathways as well as biotechnological developments in this commercially and ecologically significant species.

Physicochemical characterization and identification of major linear epitopes of sarcoplasmic calcium-binding protein (SCP) allergen from Pacific oyster (Crassostrea gigas)

BACKGROUND

Food allergy is a serious public nutritional health problem that has attracted extensive worldwide attention. Shellfish allergy is a long-lasting disorder that has a lifelong impact on health. Sarcoplasmic calcium-binding protein (SCP) plays a vital role in cell and muscle functions and has been identified as an allergen in oyster.

RESULTS

In this study, recombinant SCP (rSCP) with a molecular mass of 21 kDa was produced and identified based on SCP amino acid sequencing of Pacific oyster (Crassostrea gigas), and was used as a follow-up experimental material. Its physicochemical characterization showed that purified rSCP is highly stable to heat and acid-alkali and trypsin digestion but less resistant to pepsin digestion. We established an animal sensitization model and rSCP displayed stronger Immunoglobulin E (IgE)-binding activity with rat serum in the rSCP + cholera toxin (CT) group compared with the CT group and a control group. Five epitope peptides were identified as linear immunodominant epitopes by indirect competitive enzyme-linked immunosorbent assay (icELISA) for the first time. We also found that conformational epitopes may play a major role in the immunoreactivity of SCP.

CONCLUSION

These results are significant for understanding hypersensitization of humans to oyster and offer available preventive measures and treatment programs in further research. © 2021 Society of Chemical Industry.

Growth trait gene analysis of kuruma shrimp (Marsupenaeus japonicus) by transcriptome study

Growth traits are a vital standard for the animal culture industry. The molecular mechanism of growth traits remains poorly understood, especially in aquaculture, which hinders the development of the selective breeding industry. Genomic resources discovered by next-generation sequencing (NGS) have been widely applied in certain species. However, accurate assembly and downstream analysis by NGS are still major challenges for species without reference genomes. In this study, a comparative transcriptome analysis of an economic crustacean species (Marsupenaeus japonicus) between a fast growth group and slow growth group at different stages was performed by SMRT (single molecule real time) and NGS. A high-quality full-length transcriptome (e.g., mean length of unigenes was longer than those unigenes assembled by Illumina clean reads from previous reports, and annotation rate was higher than Illumina sequencing in the same studies) was generated and analyzed. Several differentially expressed genes (DEGs) related to growth were identified and validated by quantitative real-time PCR (qPCR). The results showed that compared with the late stage, more DEGs were identified at the early stage, indicating that the growth-related physiological activity differences between different individuals at the early stage were higher than at the late stage. Moreover, 215 DEGs were shared between the early stage and late stage, and 109 had divergent functions during development. These 109 genes may play an important role in regulating the specific growth rate (SGR) of kuruma shrimp. In addition, twelve growth-related pathways were shared between the two comparative groups. Among these pathways, the fly Hippo signaling pathway and its key gene Mj14-3-3-like were identified for the first time to be involved in growth traits in crustaceans. Further analysis showed that Mj14-3-3-like was significantly downregulated in the fast growth group at the early stage and late stage; its expression level was reduced to its lowest level at the intermolt stage (C), the most important growth stage in shrimp, suggesting that Mj14-3-3-like may inhibit the growth of kuruma shrimp. Our study helps to elucidate the genes involved in the molecular mechanisms governing growth traits in kuruma shrimp, which is valuable for future shrimp developmental research.

Potential muscle activity disturbance in Penaeus monodon during Acute Hepatopancreatic Necrosis Disease (AHPND) infection: Inference through gene expression, calcium concentration, and MicroRNA

Global shrimp aquaculture farmers have suffered major economic losses due to disease outbreaks. A notable shrimp disease is Acute Hepatopancreatic Necrosis Disease (AHPND), which is caused by a new strain of Vibrio parahaemolyticus bacteria (Vp_AHPND) that mainly inhabits the shrimp gut and damages the hepatopancreas. Fewer studies have investigated whether this disease will affect shrimp muscle functioning or cause any muscle damage. We challenged Penaeus monodon shrimp with Vp_AHPND bacteria using an immersion method. Expression of Dystrophin gene, an important regulatory gene for maintenance of muscle integrity, was quantified from muscle samples using qRT-PCR. Additional verification was conducted by determining calcium concentration and bta-miR-4286 and dre-miR-107b miRNAs expression. P. monodon dystrophin gene demonstrated the highest expression level during AHPND infection when muscle calcium concentration was detected at its lowest level at 6 h post-infection (hpi). The highest muscle calcium concentration, determined at 36 hpi, was supported by higher bta-miR-4286 miRNA expression and lower dre-miR-107b miRNA expression in Vp_AHPND-infected samples compared to uninfected samples at the same time point. We deduced an interactive relationship between dystrophin gene expression, calcium concentration, and miRNA expression in P. monodon muscle tissues triggered by the invading Vp_AHPND bacterium.

Soluble calcium-binding proteins (SCBPs) of the earthworm Lumbricus terrestris: possible role as relaxation factors in muscle

The soluble Ca²⁺-binding protein (SCBP) from the earthworm Lumbricus terrestris was analyzed with regard to its role as a soluble muscle relaxation factor. The actomyosin ATPase activity was inhibited by the addition of decalcified SCBP as it binds Ca²⁺ stronger than the regulatory proteins associated with the actomyosin. Competitive ⁴⁵Ca²⁺-binding assays with decalcified actomyosin and SCBP showed that ⁴⁵Ca²⁺ is first bound to actomyosin and is subsequently taken over by SCBP with increasing incubation time. Ca²⁺ competition experiments carried out with ⁴⁵Ca²⁺ loaded SCBP and fragmented sarcoplasmic reticulum vesicles revealed that ⁴⁵Ca²⁺ bound to SCBP can be deprived by the ATP-dependent Ca²⁺ uptake of the sarcoplasmic reticulum. Furthermore, experiments in a diffusion chamber showed that the addition of SCBP significantly enhances the ⁴⁵Ca²⁺ flux in a concentration dependent manner. The amount of the Ca²⁺ flux increase tends to reach a maximum value of about 70%. With all protein components isolated from the obliquely striated muscle, our in vitro experiments consistently show that SCBP may accelerate muscle relaxation similar as assumed for vertebrate parvalbumin.

A Proteomic Study of Hemocyte Proteins from Mud Crab (Scylla paramamosain) Infected with White Spot Syndrome Virus or Vibrio alginolyticus

In this study, we investigated the hemocytes' immune response to white spot syndrome virus (WSSV) or Vibrio alginolyticus infection at the protein level. The differential proteomes from crab hemocytes infected with WSSV or V. alginolyticus were analyzed using the isobaric tags for relative and absolute quantitation approach immediately after infection. Using this approach, we identified 1,799 proteins by their by LC-MS/MS spectra and sequencing data. These included 157 upregulated proteins and 164 downregulated proteins after WSSV infection. Similarly, 243 proteins were determined to be differentially expressed during V. alginolyticus infection, of these, 121 were upregulated and 122 were downregulated after infection. Interestingly, among these differentially expressed proteins, 106 were up- or downregulated significantly in both WSSV and V. alginolyticus infection. Six genes, β-actin, myosin-9, anti-lipopolysaccharide factor isoform 4, anti-lipopolysaccharide factor 4, transketolase-like protein 2-like isoform 1, and sarcoplasmic calcium-binding protein 1 were chosen for further study. The expression of these genes all showed a trend of upregulation at 24 h post-WSSV or V. alginolyticus infection except for myosin-9 in response to WSSV. To confirm the protective effects of the six genes, crabs were injected with specific dsRNAs before WSSV or V. alginolyticus challenge. The results showed that the knockdown of these genes led to an increase in the morbidity and mortality (P < 0.01) rate, and a decrease in infection time in WSSV-infected crabs. During the first 84 h, knockdown of these genes also led to an increase in the morbidity rates in V. alginolyticus -infected crabs, and results of four genes showed a higher mortality rate than that of the control after they were knocked down. This is the first report of the proteome response in crab hemocytes during WSSV or V. alginolyticus infection. These findings will contribute to our understanding of the immune response to WSSV and V. alginolyticus infection in crabs.

Soluble calcium-binding proteins (SCBPs) of the earthworm Lumbricus terrestris: molecular characterization and localization by FISH in muscle and neuronal tissue

Soluble calcium-binding proteins (SCBPs) of invertebrates probably serve like their vertebrate counterpart-the parvalbumins-as soluble relaxing factors in muscles. Three SCBP isoforms (SCBP_1-3) have been isolated and biochemically characterized in the earthworm Lumbricus terrestris (Huch et al. in J Comp Physiol B 158:325-334, 1988). For SCBP₂, we found two isoforms named SCBP_2a/2b. Both of them together with SCBP₃ are present in the body wall muscle. In the gizzard solely, SCBP_2b and no SCBP_2a or SCBP₃ could be detected. The coding sequences of all three isoforms consist of 534 bp for 178 amino acids and contain four EF-hand motifs, of which the second EF-hands are truncated. Recombinant proteins show heat stability and a Ca²⁺-dependent mobility shift similar to the native proteins, indicating comparable calcium-binding properties. All three isoforms are encoded by three distinct and differentially expressed genes. The genes for SCBP_2a, SCBP_2b, and SCBP₃ are interrupted by only one intron, inserting at nearly the same positions. Northern blot analysis revealed two mRNA transcripts for SCBP₂ of approximately 1250 and 1500 kb and one transcript for SCBP₃ of approximately 1250 kb. SCBP mRNA was localized by fluorescent in situ hybridization in the body wall and the gizzard. The distribution of the staining intensities resembles that for the myosin ATPase activity and indicates a correlation between the amount of SCBP and speed of muscle contraction. In addition, SCBP mRNA was localized within the nervous tissue, the cerebral and subesophageal ganglia and the ventral nerve cord.

An integrated proteomic and metabolomic study on the gender-specific responses of mussels Mytilus galloprovincialis to tetrabromobisphenol A (TBBPA)

Tetrabromobisphenol A (TBBPA), accounting for the largest production of brominated flame-retardants (BFRs) along the Laizhou Bay in China, is of great concern due to its diverse toxicities. In this study, we focused on the gender-specific responses of TBBPA in mussel Mytilus galloprovincialis using an integrated proteomic and metabolomic approach. After exposure of TBBPA (10 µg L(-1)) for one month, a total of 9 metabolites and 67 proteins were altered in mussel gills from exposed group. The significant changes of metabolites in female mussel gills from exposed group exhibited the disturbances in energy metabolism and osmotic regulation, while in male samples only be found the variation of metabolites related to osmotic regulation. iTRAQ-based proteomic analysis showed biological differences between male and female mussel gills from solvent control group. The higher levels of proteins related to primary and energy metabolism and defense mechanisms in male mussel gills meant a greater anti-stress capability of male mussels. Further analysis revealed that TBBPA exposure affected multiple biological processes consisting of production and development, material and energy metabolism, signal transduction, gene expression, defense mechanisms and apoptosis in both male and female mussels with different mechanisms. Specially, the responsive proteins of TBBPA in male mussels signified higher tolerance limits than those in female individuals, which was consistent with the biological differences between male and female mussel gills from solvent control group. This work suggested that the gender differences should be considered in ecotoxicology.

Identification and Characterization of Reference Genes for Normalizing Expression Data from Red Swamp Crawfish Procambarus clarkii

qRT-PCR is a widely used technique for rapid and accurate quantification of gene expression data. The use of reference genes for normalization of the expression levels is crucial for accuracy. Several studies have shown that there is no perfect reference gene that is appropriate for use in all experimental conditions, and research on suitable reference genes in red swamp crawfish (Procambarus clarkii) is particularly scarce. In this study, eight commonly used crustacean reference genes were chosen from P. clarkii transcriptome data and investigated as potential candidates for normalization of qRT-PCR data. Expression of these genes under different experimental conditions was examined by qRT-PCR, and the stability of their expression was evaluated using three commonly used statistical algorithms, geNorm, NormFinder and BestKeeper. A final comprehensive ranking determined that EIF and 18S were the optimal reference genes for expression data from different tissues, while TBP and EIF were optimal for expression data from different ovarian developmental stages. To our knowledge, this is the first systematic analysis of reference genes for normalization of qRT-PCR data in P. clarkii. These results will facilitate more accurate and reliable expression studies of this and other crustacean species.

Proteomic analysis of differentially expressed protein in hemocytes of wild giant freshwater prawn Macrobrachium rosenbergii infected with infectious hypodermal and hematopoietic necrosis virus (IHHNV)

Epizootic diseases cause huge mortality and economical loses at post larvae stages in freshwater prawn aquaculture industry. These prawns seem less susceptible to viral diseases except for infectious hypodermal and hematopoietic necrosis virus (IHHNV). During viral infection in prawns, hemocytes are the primary organ that shows immunological response within the early stages of infection. We applied proteomic approaches to understand differential expression of the proteins in hemocytes during the viral disease outbreak. To aid the goal, we collected Macrobrachium rosenbergii broodstocks from the local grow out hatchery which reported the first incidence of IHHNV viral outbreak during larvae stage. Primarily, application of the OIE primer targeting 389 bp fragments of IHHNV virus was used in identification of the infected and non-infected samples of the prawn breeding line. Analysis of two-dimensional gel electrophoresis showed specific down-regulation of Arginine kinase and Sarcoplasmic calcium-binding protein and up/down-regulation of Prophenoloxidase1 and hemocyanin isoforms. These proteins were validated using semi quantitative RT-PCR and gene transcripts at mRNA level. These identified proteins can be used as biomarkers, providing a powerful approach to better understanding of the immunity pathway of viral disease with applications in analytic and observational epidemiology diagnosis. Proteomic profiling allows deep insight into the pathogenesis of IHHNV molecular regulation and mechanism of hemocyte in freshwater prawns.

The proteomic response of cheliped myofibril tissue in the eurythermal porcelain crab Petrolisthes cinctipes to heat shock following acclimation to daily temperature fluctuations

The porcelain crab Petrolisthes cinctipes lives under rocks and in mussel beds in the mid-intertidal zone where it experiences immersion during high tide and saturating humid conditions in air during low tide, which can increase habitat temperature by up to 20°C. To identify the biochemical changes affected by increasing temperature fluctuations and subsequent heat shock, we acclimated P. cinctipes for 30 days to one of three temperature regimes: (1) constant 10°C, (2) daily temperature fluctuations between 10 and 20°C (5 h up-ramp to 20°C, 1 h down-ramp to 10°C) and (3) 10–30°C (up-ramp to 30°C). After acclimation, animals were exposed to either 10°C or a 30°C heat shock to analyze the proteomic changes in claw muscle tissue. Following acclimation to 10–30°C (measured at 10°C), enolase and ATP synthase increased in abundance. Following heat shock, isoforms of arginine kinase and glycolytic enzymes such as aldolase, triose phosphate isomerase and glyceraldehyde 3-phosphate dehydrogenase increased across all acclimation regimes. Full-length isoforms of hemocyanin increased abundance following acclimation to 10–30°C, but hemocyanin fragments increased after heat shock following constant 10°C and fluctuating 10–20°C, possibly playing a role as antimicrobial peptides. Following constant 10°C and fluctuating 10–20°C, paramyosin and myosin heavy chain type-B increased in abundance, respectively, whereas myosin light and heavy chain decreased with heat shock. Actin-binding proteins, which stabilize actin filaments (filamin and tropomyosin), increased during heat shock following 10–30°C; however, actin severing and depolymerization proteins (gelsolin and cofilin) increased during heat shock following 10–20°C, possibly promoting muscle fiber restructuring. RAF kinase inhibitor protein and prostaglandin reductase increased during heat shock following constant 10°C and fluctuating 10–20°C, possibly inhibiting an immune response during heat shock. The results suggest that ATP supply, muscle fiber restructuring and immune responses are all affected by temperature fluctuations and subsequent acute heat shock in muscle tissue. Furthermore, although heat shock after acclimation to constant 10°C and fluctuating 10–30°C showed the greatest effects on the proteome, moderately fluctuating temperatures (10–20°C) broadened the temperature range over which claw muscle was able to respond to an acute heat shock with limited changes in the muscle proteome.

Identification of a novel allergen from muscle and various organs in banana shrimp (Fenneropenaeus merguiensis)

BACKGROUND

The increasing consumption of shellfish can cause an increase in allergic symptoms. Shrimp allergy can be species specific, but specific allergies in different organs have not been studied. Identification of allergens in muscle and others organs of banana shrimp is necessary for improved diagnostics of allergies for shrimp and food safety control.

OBJECTIVE

To identify the IgE-binding proteins in various organs of Fenneropenaeus merguiensis by immunoblotting and tandem mass spectrometry.

METHODS

Proteomic methods were used to investigate the allergenic proteins from banana shrimp. Proteins from muscle and various organs were separated by denaturing polyacrylamide gel electrophoresis. Allergens were analyzed by immunoblotting with pooled sera from shrimp allergic patients (n = 21) and tandem mass spectrometry.

RESULTS

The important allergens in banana shrimp are arginine kinase, sarcoplasmic calcium-binding protein, myosin heavy chain, hemocyanin, enolase, and glyceraldehyde-3-phosphate dehydrogenase, which can be demonstrated by immunoblotting in muscle and shell. Moreover, vitellogenin, ovarian peritrophin 1 precursor, β-actin, and 14-3-3 protein were suggested as allergens in the ovary at different stages of ovarian development.

CONCLUSION

Ten allergens were identified as allergens in various organs, and they are suggested as novel allergens in banana shrimp. The major allergen in muscle and shell from this shrimp is arginine kinase, whereas the major allergen in the ovary is vitellogenin.

A 24-48 h fed Amblyomma americanum tick saliva immuno-proteome

BACKGROUND

Multiple tick saliva proteins, the majority of which are unknown, confer tick resistance in repeatedly infested animals. The objective of this study was to identify the 24-48 h fed Amblyomma americanum tick saliva immuno-proteome. The 24-48 h tick-feeding phase is critical to tick parasitism as it precedes important events in tick biology, blood meal feeding and disease agent transmission. Fed male, 24 and 96 h fed female phage display cDNA expression libraries were biopanned using rabbit antibodies to 24 and 48 h fed A. americanum female tick saliva proteins. Biopanned immuno-cDNA libraries were subjected to next generation sequencing, de novo assembly, and bioinformatic analysis.

RESULTS

More than 800 transcripts that code for 24-48 h fed A. americanum immuno-proteins are described. Of the 895 immuno-proteins, 52% (464/895) were provisionally identified based on matches in GenBank. Of these, ~19% (86/464) show high level of identity to other tick hypothetical proteins, and the rest include putative proteases (serine, cysteine, leukotriene A-4 hydrolase, carboxypeptidases, and metalloproteases), protease inhibitors (serine and cysteine protease inhibitors, tick carboxypeptidase inhibitor), and transporters and/or ligand binding proteins (histamine binding/lipocalin, fatty acid binding, calreticulin, hemelipoprotein, IgG binding protein, ferritin, insulin-like growth factor binding proteins, and evasin). Others include enzymes (glutathione transferase, cytochrome oxidase, protein disulfide isomerase), ribosomal proteins, and those of miscellaneous functions (histamine release factor, selenoproteins, tetraspanin, defensin, heat shock proteins).

CONCLUSIONS

Data here demonstrate that A. americanum secretes a complex cocktail of immunogenic tick saliva proteins during the first 24-48 h of feeding. Of significance, previously validated immunogenic tick saliva proteins including AV422 protein, calreticulin, histamine release factor, histamine binding/lipocalins, selenoproteins, and paramyosin were identified in this screen, supporting the specificity of the approach in this study. While descriptive, this study opens opportunities for in-depth tick feeding physiology studies.

Protein profiling in the gut of Penaeus monodon gavaged with oral WSSV-vaccines and live white spot syndrome virus

White spot syndrome virus (WSSV) is a pathogen that causes considerable mortality of the farmed shrimp, Penaeus monodon. Candidate 'vaccines', WSSV envelope protein VP28 and formalin-inactivated WSSV, can provide short-lived protection against the virus. In this study, P. monodon was orally intubated with the aforementioned vaccine candidates, and protein expression in the gut of immunised shrimps was profiled. The alterations in protein profiles in shrimps infected orally with live-WSSV were also examined. Seventeen of the identified proteins in the vaccine and WSSV-intubated shrimps varied significantly compared to those in the control shrimps. These proteins, classified under exoskeletal, cytoskeletal, immune-related, intracellular organelle part, intracellular calcium-binding or energy metabolism, are thought to directly or indirectly affect shrimp's immunity. The changes in the expression levels of crustacyanin, serine proteases, myosin light chain, and ER protein 57 observed in orally vaccinated shrimp may probably be linked to immunoprotective responses. On the other hand, altered expression of proteins linked to exoskeleton, calcium regulation and energy metabolism in WSSV-intubated shrimps is likely to symbolise disturbances in calcium homeostasis and energy metabolism.

Proteomic and metabolomic responses of clam Ruditapes philippinarum to arsenic exposure under different salinities

Arsenic (As) contamination is a severe problem in the intertidal zones of the Bohai Sea (China) with wide salinity variation. In the present study, we combined proteomics and metabolomics to characterize the differential responses of arsenic in clam Ruditapes philippinarum under different salinities (31.1, 23.3 and 15.6 psu). Both proteomic and metabolomic responses indicated that varying salinities could significantly affect the toxicological responses of clams to As. Metabolic biomarkers revealed that the environmentally relevant arsenic (20 μg L(-1)) exposure induced disturbance in energy metabolism and/or osmotic regulation under different salinities, whereas protein biomarkers indicated oxidative stress, cellular injury and apoptosis and disturbance in energy metabolism. In addition, the up-regulated proteins including ATP synthase, succinyl-CoA synthetase and nucleoside diphosphate kinase were validated by related metabolites, succinate and ATP, which confirmed the disturbance in energy metabolism in clam gills at low salinity (15.6 psu). These findings provide important insights into toxicological effects of environmental contaminant at molecular levels using combined proteomics and metabolomics.

Characterization of sarcoplasmic calcium binding protein (SCP) variants from freshwater crayfish Procambarus clarkii

Sarcoplasmic calcium binding protein (SCP) is an invertebrate EF-hand calcium buffering protein that has been proposed to fulfill a similar function in muscle relaxation as vertebrate parvalbumin. We have identified three SCP variants in the freshwater crayfish Procambarus clarkii. The variants (pcSCP1a, pcSCP1b, and pcSCP1c) differ across a 37 amino acid region that lies mainly between the second and third EF-hand calcium binding domains. We evaluated tissue distribution and response of the variants to cold exposure, a stress known to affect expression of parvalbumin. Expression patterns of the variants were not different and therefore do not provide a functional rationale for the polymorphism of pcSCP1. Compared to hepatopancreas, expression of pcSCP1 variants was 100,000-fold greater in axial abdominal muscle and 10-fold greater in cardiac muscle. Expression was 10-100 greater in fast-twitch deep flexor and extensor muscles compared to slow-twitch superficial flexor and extensors. In axial muscle, no significant changes of pcSCP1, calmodulin (CaM), or sarcoplasmic/endoplasmic reticulum Ca-ATPase (SERCA) expression were measured after one week of 4°C exposure. In contrast, large decreases of pcSCP1 were measured in cardiac muscle, with no changes in CaM or SERCA. Knockdown of pcSCP1 by dsRNA led to reduced muscle activity and decreased expression of SERCA. In summary, the pattern of pcSCP1 tissue expression is similar to parvalbumin, supporting a role in muscle contraction. However, the response of pcSCP1 to cold exposure differs from parvalbumin, suggesting possible functional divergence between the two proteins.

Gut SCP is an immune-relevant molecule involved in the primary immunological memory or pattern recognition in the amphioxus Branchiostoma belcheri

To understand the role of calcium-binding proteins of invertebrates in immunological response, amphioxus sarcoplasmic calcium-binding protein (SCP) was investigated in the present study. Following gene cloning, recombinant protein expression and purification and antibody preparation, the expression and alteration of SCP in the response to bacterial challenge were detected using Western blotting. SCP was not detected in the branchia, humoral fluid, gonad or in the gut of wounded animals, but it was abundant in muscle and appeared in the gut of healthy animals using Vibrio parahaemolyticus immunization and challenge. Furthermore, whether gut SCP possessed anamnestic response was investigated using cross-immune challenge between Gram-positive and -negative bacteria. Gut SCP showed stronger anamnestic activity or pattern-recognition in response to Gram-negative bacterium V. parahaemolyticus than Gram-positive bacterium Staphylococcus aureus. The response was faster and more species-specific to V. parahaemolyticus, whereas it was slower and longer to S. aureus. The reason why the response showed significant difference between Gram-positive and -negative bacteria awaits investigation. These results indicate that gut SCP is an immune-relevant molecule involved in the primary immunological memory or pattern recognition in the amphioxus Branchiostoma belcheri.

Molecular genetic differentiation in earthworms inhabiting a heterogeneous Pb-polluted landscape

A Pb-mine site situated on acidic soil, but comprising of Ca-enriched islands around derelict buildings was used to study the spatial pattern of genetic diversity in Lumbricus rubellus. Two distinct genetic lineages ('A' and 'B'), differentiated at both the mitochondrial (mtDNA COII) and nuclear level (AFLPs) were revealed with a mean inter-lineage mtDNA sequence divergence of approximately 13%, indicative of a cryptic species complex. AFLP analysis indicates that lineage A individuals within one central 'ecological island' site are uniquely clustered, with little genetic overlap with lineage A individuals at the two peripheral sites. FTIR microspectroscopy of Pb-sequestering chloragocytes revealed different phosphate profiles in residents of adjacent acidic and calcareous islands. Bioinformatics found over-representation of Ca pathway genes in EST(Pb) libraries. Subsequent sequencing of a Ca-transport gene, SERCA, revealed mutations in the protein's cytosolic domain. We recommend the mandatory genotyping of all individuals prior to field-based ecotoxicological assays, particularly those using discriminating genomic technologies.

Cloning and characterization of a calmodulin gene (CaM) in crayfish Procambarus clarkii and expression during molting

Calmodulin (CaM) is a highly conserved calcium (Ca(2+)) binding protein that transduces Ca(2+) signals into downstream effects influencing a range of cellular processes, including Ca(2+) homeostasis. The present study explores CaM expression when Ca(2+) homeostasis is challenged during the mineralization cycle of the freshwater crayfish (Procambarus clarkii). In this paper we report the cloning of a CaM gene from axial abdominal crayfish muscle (referred to as pcCaM). The pcCaM mRNA is ubiquitously expressed but is far more abundant in excitable tissue (muscle, nerve) than in any epithelia (gill, antennal gland, digestive) suggesting that it plays a greater role in the biology of excitation than in epithelial ion transport. In muscle cells the pcCaM was colocalized on the plasma membrane with the Ca(2+) ATPase (PMCA) known to regulate intracellular Ca(2+) through basolateral efflux. While PMCA exhibits a greater upregulation in epithelia (than in non-epithelial tissues) during molting stages requiring transcellular Ca(2+) flux (pre- and postmolt compared with intermolt), expression of pcCaM exhibited a uniform increase in epithelial and non-epithelial tissues alike. The common increase in expression of CaM in all tissues during pre- and postmolt stages (compared with intermolt) suggests that the upregulation is systemically (hormonally) mediated. Colocalization of CaM with PMCA confirms physiological findings that their regulation is linked.

Elongation factor 1Bgamma (eEF1Bgamma) expression during the molting cycle and cold acclimation in the crayfish Procambarus clarkii

Eukaryotic elongation factor 1Bgamma (eEF1Bgamma) is a subunit of elongation factor 1 (EF1), which regulates the recruitment of amino acyl-tRNAs to the ribosome during protein synthesis in eukaryotes. In addition to structural roles within eEF1, eEF1Bgamma has properties which suggest sensory or regulatory activities. We have cloned eEF1Bgamma from axial abdominal muscle of freshwater crayfish, Procambarus clarkii. The predicted amino acid sequence has 66% identity to Locusta migratoria eEF1Bgamma and 65% identity to Artemia salina eEF1Bgamma. We measured eEF1Bgamma expression by real-time PCR, using the relative quantification method with 18s ribosomal RNA as an internal calibrator. eEF1Bgamma expression was lowest in gill, axial abdominal muscle, and hepatopancreas, and was highest in the antennal gland (5.7-fold above hepatopancreas) and cardiac muscle (7.8-fold above hepatopancreas). In axial abdominal muscle, eEF1Bgamma expression was 4.4-fold higher in premolt and 11.9 higher in postmolt compared to intermolt. In contrast, eEF1Bgamma was decreased or unchanged in epithelial tissues during pre- and postmolt. eEF1Bgamma expression in the hepatopancreas was 3.5-fold higher during intermolt compared to premolt and was unchanged in gill and antennal gland. No significant differences in eEF1Bgamma were found after 1 week of acclimation to 4 degrees C. These results show that eEF1Bgamma is regulated at the mRNA level with tissue-specific differences in expression patterns.

Paradox of epithelial cell calcium homeostasis during vectorial transfer in crayfish kidney

The molting cycle of the freshwater crayfish, Procambarus clarkii, has been used as a model to study the cellular physiology and molecular biology of Ca "supply" proteins that effect transcellular vectorial Ca(2+) movement to achieve organismal Ca homeostasis. Specifically, periods of net Ca(2+) influx (postmolt) have been compared with periods of net Ca(2+) balance (intermolt). The broader goal is to understand the paradox facing epithelial cells of maintaining low cytosolic Ca(2+)in the face of mass Ca(2+)transit across epithelial cells. This mini-review compares mRNA and protein expression profiles for a series of proteins that are of strategic importance in effecting transcellular Ca(2+) flux in a selected epithelium, the antennal gland (kidney analog) specifically during apical to basolateral Ca(2+) conveyance. Target proteins were selected as representative of key "stages" in the transcellular transfer of Ca(2+): import (epithelial Ca(2+) channel, ECaC); storage (sarco/endoplasmic reticulum Ca(2+) ATPase, SERCA); buffering (sarcoplasmic Ca(2+) binding protein, SCP); and export (plasma membrane Ca(2+) ATPase, PMCA and Na(+)/Ca(2+) exchanger, NCX). The purpose of this review is to assess coordination of expression of these target proteins at times of high Ca(2+) demand (premolt and postmolt) compared to low Ca demand (intermolt) as a function of cellular location (apical vs. basolateral; endomembranes vs. plasma membranes) and relative abundance within different regions of the antennal gland. Understanding the spatiotemporal regulation of Ca(2+) handling proteins involved in transcellular transport is fundamental to investigating their endocrine regulation.

Comparative analysis of differentially expressed genes in normal and white spot syndrome virus infected Penaeus monodon

Background

White spot syndrome (WSS) is a viral disease that affects most of the commercially important shrimps and causes serious economic losses to the shrimp farming industry worldwide. However, little information is available in terms of the molecular mechanisms of the host-virus interaction. In this study, we used an expressed sequence tag (EST) approach to observe global gene expression changes in white spot syndrome virus (WSSV)-infected postlarvae of Penaeus monodon.

Results

Sequencing of the complementary DNA clones of two libraries constructed from normal and WSSV-infected postlarvae produced a total of 15,981 high-quality ESTs. Of these ESTs, 46% were successfully matched against annotated genes in National Center of Biotechnology Information (NCBI) non-redundant (nr) database and 44% were functionally classified using the Gene Ontology (GO) scheme. Comparative EST analyses suggested that, in postlarval shrimp, WSSV infection strongly modulates the gene expression patterns in several organs or tissues, including the hepatopancreas, muscle, eyestalk and cuticle. Our data suggest that several basic cellular metabolic processes are likely to be affected, including oxidative phosphorylation, protein synthesis, the glycolytic pathway, and calcium ion balance. A group of immune-related chitin-binding protein genes is also likely to be strongly up regulated after WSSV infection. A database containing all the sequence data and analysis results is accessible at .

Conclusion

This study suggests that WSSV infection modulates expression of various kinds of genes. The predicted gene expression pattern changes not only reflect the possible responses of shrimp to the virus infection but also suggest how WSSV subverts cellular functions for virus multiplication. In addition, the ESTs reported in this study provide a rich source for identification of novel genes in shrimp.

Molecular characteristics and expression analysis of calreticulin in Chinese shrimp Fenneropenaeus chinensis

Calreticulin (CRT), as an endoplasmic reticulum luminal resident protein, plays important roles in Ca(2+) homeostasis and molecular chaperoning. CRT on the surface of the cell can modulate cell adhesion, phagocytosis and integrin-dependent Ca(2+) signaling. The full length cDNA of calreticulin (FcCRT) was cloned from Chinese shrimp Fenneropenaeus chinensis. It consists of 1672 bp with an open reading frame of 1221 bp, encoding 406 amino acids. This is the first reported cDNA sequence of calreticulin in Crustacea. The deduced amino acid sequence of FcCRT showed high identity with those of Bombyx mori (88%), Drosophila melanogaster (83%), Mus musculus (82%) and Homo sapiens (82%). Highest expression of FcCRT was detected in ovary by Northern blot and in situ hybridization. Different mRNA levels of FcCRT were detected at various molting stages. Expression of FcCRT was induced significantly after 3 h of heat shock treatment, reached the maximum at 4 h and dropped after that. Differential expression profiles of FcCRT were observed in hepatopancreas and haemocytes when shrimp were challenged by white spot syndrome virus (WSSV). From the above results, we inferred that FcCRT might play important roles in Ca(2+) homeostasis, chaperoning and immune function in shrimp.

Roles of NCX and PMCA in Basolateral Calcium Export Associated with Mineralization Cycles and Cold Acclimation in Crayfish

Basolateral Na+/Ca2+ exchanger (NCX) and plasma membrane Ca2+ ATPase (PMCA) are the primary transmembrane proteins that export calcium (Ca2+) from cells. In our lab we use a nonmammalian animal model, the freshwater crayfish, to study cellular Ca2+ regulation. Two experimental conditions are employed to effect Ca2+ dyshomeostasis: (a) in the postmolt stage of the crustacean molting cycle increased unidirectional Ca2+ influx associated with cuticular mineralization is accompanied by elevated basolateral Ca2+ export (compared with intermolt Ca balance); and (b) exposure of the poikilothermic crayfish to cold acclimation (4 degrees C) causes influx of Ca2+ into cells, which is compensated by increased basolateral Ca2+ export (compared with exposure to 23 degrees C). This study compares expression of both NCX and PMCA mRNA (real-time PCR) and protein (Western) in both epithelial (kidney) and nonepithelial tissue (tail muscle) during elevated basolateral Ca2+ export. Both experimental treatments produced increases in NCX and PMCA expression (mRNA and protein) in both tissues. Mineralization produced greater upregulation of mRNA in kidney than in tail, whereas cold acclimation yielded comparable increases in both tissues. Protein expression patterns were generally confirmatory of real-time PCR data although expression changes were less pronounced. Both experimental treatments appear to increase basolateral Ca2+ export.

Stimulation of Mg2+-independent form of Ca2+-ATPase by a low molecular mass protein purified from goat testes cytosol

A low molecular mass protein purified from goat (Capra hircus) testes cytosol following gel filtration and anion exchange chromatographic separation stimulates Mg(2+)-independent Ca(2+)-ATPase activity without any significant effect on Mg(2+)-dependent Ca(2+)-ATPase. Stimulation of the ATPase is due to an increase in the rate of dephosphorylation of the overall reaction step of the enzyme. Binding of the stimulator increases the affinity of Ca(2+)-ATPase for Ca(2+). An analysis of enzyme kinetics reveals a reversible type of binding of the stimulator to the ATPase and non-competitive type of stimulation with respect to the substrate. Stimulation seems due to binding of the protein at a single site following Michaelis-Menten model. The protein can also counter the effect of calcium antagonists exerted on the ATPase. The pI of the protein is 6.2 and its molecular mass has been determined to be 13, 961 by Q-TOF-MS.