Emergence of the acute-phase protein hemopexin in jawed vertebrates

Exploration of the Nurse Shark (Ginglymostoma cirratum) Plasma Immunoproteome Using High-Resolution LC-MS/MS

Many animals of scientific importance lack species-specific reagents (e.g., monoclonal antibodies) for in-depth studies of immune proteins. Mass spectrometry (MS)-based proteomics has emerged as a useful method for monitoring changes in protein abundance and modifications in non-model species. It can be used to quantify hundreds of candidate immune molecules simultaneously without the generation of new reagents. Here, we used MS-based proteomics to identify and quantify candidate immune proteins in the plasma of the nurse shark (Ginglymostoma cirratum), a cartilaginous fish and representative of the most basal extant vertebrate lineage with an immunoglobulin-based immune system. Mass spectrometry-based LC-MS/MS was performed on the blood plasma of nurse sharks immunized with human serum albumin (n=4) or sham immunized (n=1), and sampled at days 0 (baseline control), 1, 2, 3, 5, 7, 14, 21, 28, 25, 42 and 49. An antigen-specific antibody response was experimentally confirmed post-immunization. To provide a high-quality reference to identify proteins, we assembled and annotated a multi-tissue de novo transcriptome integrating long- and short-read sequence data. This comprised 62,682 contigs containing open reading frames (ORFs) with a length >80 amino acids. Using this transcriptome, we reliably identified 626 plasma proteins which were broadly categorized into coagulation, immune, and metabolic functional groups. To assess the feasibility of performing LC-MS/MS proteomics in nurse shark in the absence of species-specific protein annotations, we compared the results to an alternative strategy, mapping peptides to proteins predicted in the genome assembly of a related species, the whale shark (Rhincodon typus). This approach reliably identified 297 proteins, indicating that useful data on the plasma proteome may be obtained in many instances despite the absence of a species-specific reference protein database. Among the plasma proteins defined against the nurse shark transcriptome, fifteen showed consistent changes in abundance across the immunized shark individuals, indicating a role in the immune response. These included alpha-2-macroglobulin (A2M) and a novel protein yet to be characterized in diverse vertebrate lineages. Overall, this study enhances genetic and protein-level resources for nurse shark research and vastly improves our understanding of the elasmobranch plasma proteome, including its remodelling following immune stimulation.

Human Serum Albumin Facilitates Heme-Iron Utilization by Fungi

Heme constitutes a major iron source for microorganisms and particularly for pathogenic microbes; to overcome the iron scarcity in the animal host, many pathogenic bacteria and fungi have developed systems to extract and take up heme from host proteins such as hemoglobin. Microbial heme uptake mechanisms are usually studied using growth media containing free heme or hemoglobin as a sole iron source. However, the animal host contains heme-scavenging proteins that could prevent this uptake. In the human host in particular, the most abundant serum heme-binding protein is albumin. Surprisingly, however, we found that in the case of fungi of the Candida species family, albumin promoted rather than prevented heme utilization. Albumin thus constitutes a human-specific factor that can affect heme-iron utilization and could serve as target for preventing heme-iron utilization by fungal pathogens. As a proof of principle, we identify two drugs that can inhibit albumin-stimulated heme utilization.

A large portion of biological iron is found in the form of an iron-protoporphyrin IX complex, or heme. In the human host environment, which is exceptionally poor in free iron, heme iron, particularly from hemoglobin, constitutes a major source of iron for invading microbial pathogens. Several fungi were shown to utilize free heme, and Candida albicans, a major opportunistic pathogen, is able both to capture free heme and to extract heme from hemoglobin using a network of extracellular hemophores. Human serum albumin (HSA) is the most abundant host heme-scavenging protein. Tight binding of heme by HSA restricts its toxic chemical reactivity and could diminish its availability as an iron source for pathogenic microbes. We found, however, that rather than inhibiting heme utilization, HSA greatly increases availability of heme as an iron source for C. albicans and other fungi. In contrast, hemopexin, a low-abundance but high-affinity heme-scavenging serum protein, does inhibit heme utilization by C. albicans. However, inhibition by hemopexin is mitigated in the presence of HSA. Utilization of albumin-bound heme requires the same hemophore cascade as that which mediates hemoglobin-iron utilization. Accordingly, we found that the C. albicans hemophores are able to extract heme bound to HSA in vitro. Since many common drugs are known to bind to HSA, we tested whether they could interfere with heme-iron utilization. We show that utilization of albumin-bound heme by C. albicans can be inhibited by the anti-inflammatory drugs naproxen and salicylic acid.

Involvement of apolipoprotein A in maintaining tissue fluid balance in goldfish Carassius auratus

Mammalian plasma proteins play a key role in maintaining tissue fluid balance because they are retained within capillaries and thus create colloid osmotic pressure. Likewise, fish plasma contain a considerable concentration oligomeric proteins which likely serve a similar role. To elucidate the functions of these oligomeric proteins, we analyzed blood serum (BS) and interstitial fluid (IF) complexes in goldfish from the wild and under experimental conditions using 2D electrophoresis and matrix-assisted laser desorption/ionization (MALDI). We detected protein compounds with MWs ranging from 50 to 155 kDa, organized as oligomeric complexes. The protein compounds consisted of apolipoproteins АроА-I and Аро-14 which are homological to mammalian АроА-I and АроА-II, respectively. The 155-kDa and 50-125-kDa oligomer complexes were located very low-density lipoproteins (LDL) and high-density lipoproteins (HDL) areas on the BS/IF proteomic maps, respectively. The latter resembled mammalian HDL plasma particles by size and contained lipids, so we considered them as HDL particle populations. Investigation of the uniform dissociation/association mechanism for HDL and LDL oligomers in goldfish, from the wild and under critical salinity conditions, showed the "125/110 → 85/60 kDa" reorganization. This was associated with overcoming physiological stress during spawning and under critical salinity conditions. Opposite reorganization "85/60 → 125/110 kDa" was associated with restoration of metabolic processes after stress. The association/dissociation reorganizations promoted equilibration of BS and IF osmolarities in all fish groups. We discuss the connection of these reorganizations with total protein distribution across the capillary wall and salinity, as well as the role of oligomeric apolipoproteins as universal metabolic regulators.

Deiminated proteins in extracellular vesicles and plasma of nurse shark (Ginglymostoma cirratum) - Novel insights into shark immunity

Peptidylarginine deiminases (PADs) are phylogenetically conserved calcium-dependent enzymes which post-translationally convert arginine into citrulline in target proteins in an irreversible manner, causing functional and structural changes in target proteins. Protein deimination causes generation of neo-epitopes, affects gene regulation and also allows for protein moonlighting. Extracellular vesicles are found in most body fluids and participate in cellular communication via transfer of cargo proteins and genetic material. In this study, post-translationally deiminated proteins and extracellular vesicles (EVs) are described for the first time in shark plasma. We report a poly-dispersed population of shark plasma EVs, positive for phylogenetically conserved EV-specific markers and characterised by TEM. In plasma, 6 deiminated proteins, including complement and immunoglobulin, were identified, whereof 3 proteins were found to be exported in plasma-derived EVs. A PAD homologue was identified in shark plasma by Western blotting and detected an expected 70 kDa size. Deiminated histone H3, a marker of neutrophil extracellular trap formation, was also detected in nurse shark plasma. This is the first report of deiminated proteins in plasma and EVs, highlighting a hitherto unrecognized post-translational modification in key immune proteins of innate and adaptive immunity in shark.

Ancient Use of Ig Variable Domains Contributes Significantly to the TCRδ Repertoire

The loci encoding B and T cell Ag receptors are generally distinct in commonly studied mammals, with each receptor's gene segments limited to intralocus, cis chromosomal rearrangements. The nurse shark (Ginglymostoma cirratum) represents the oldest vertebrate class, the cartilaginous fish, with adaptive immunity provided via Ig and TCR lineages, and is one species among a growing number of taxa employing Ig-TCRδ rearrangements that blend these distinct lineages. Analysis of the nurse shark Ig-TCRδ repertoire found that these rearrangements possess CDR3 characteristics highly similar to canonical TCRδ rearrangements. Furthermore, the Ig-TCRδ rearrangements are expressed with TCRγ, canonically found in the TCRδ heterodimer. We also quantified BCR and TCR transcripts in the thymus for BCR (IgHV-IgHC), chimeric (IgHV-TCRδC), and canonical (TCRδV-TCRδC) transcripts, finding equivalent expression levels in both thymus and spleen. We also characterized the nurse shark TCRαδ locus with a targeted bacterial artifical chromosome sequencing approach and found that the TCRδ locus houses a complex of V segments from multiple lineages. An IgH-like V segment, nestled within the nurse shark TCRδ translocus, grouped with IgHV-like rearrangements we found expressed with TCRδ (but not IgH) rearrangements in our phylogenetic analysis. This distinct lineage of TCRδ-associated IgH-like V segments was termed "TAILVs." Our data illustrate a dynamic TCRδ repertoire employing TCRδVs, NARTCRVs, bona fide trans-rearrangements from shark IgH clusters, and a novel lineage in the TCRδ-associated Ig-like V segments.

Haptoglobin Is a Divergent MASP Family Member That Neofunctionalized To Recycle Hemoglobin via CD163 in Mammals

In mammals, haptoglobin (Hp) is an acute-phase plasma protein that binds with high affinity to hemoglobin (Hb) released by intravascular hemolysis. The resultant Hp-Hb complexes are bound and cleared by the scavenger receptor CD163, limiting Hb-induced oxidative damage. In this study, we show that Hp is a divergent member of the complement-initiating MASP family of proteins, which emerged in the ancestor of jawed vertebrates. We demonstrate that Hp has been independently lost from multiple vertebrate lineages, that characterized Hb-interacting residues of mammals are poorly conserved in nonmammalian species maintaining Hp, and that the extended loop 3 region of Hp, which mediates CD163 binding, is present only in mammals. We show that the Hb-binding ability of cartilaginous fish (nurse shark, Ginglymostoma cirratum; small-spotted catshark, Scyliorhinus canicula; and thornback ray, Raja clavata) and teleost fish (rainbow trout, Oncorhynchus mykiss) Hp is species specific, and where binding does occur it is likely mediated through a different structural mechanism to mammalian Hp. The continued, high-level expression of Hp in cartilaginous fishes in which Hb binding is not evident signals that Hp has (an)other, yet unstudied, role(s) in these species. Previous work indicates that mammalian Hp also has secondary, immunomodulatory functions that are independent of Hb binding; our work suggests these may be remnants of evolutionary more ancient functions, retained after Hb removal became the primary role of Hp in mammals.

Hypothermal stress induced differential expression profiles of the immune response gene, warm-temperature-acclimation associated 65-kDa protein (Wap65), in the liver of fresh water and seawater milkfish, Chanos chanos

The milkfish (Chanos chanos), an important aquaculture species, is intolerant to cold environments. Temperature fluctuations in the environment affect the physiological response, behavior, and survival rate of the fish. The warm-temperature-acclimation associated 65-kDa protein (Wap65) of teleosts was identified after heat shock treatment and has two isoforms. Both the isoforms were involved in the induction of immune responses in fish. They showed high degree of sequence conservation with the mammalian hemopexin and had high affinity for heme, which helped in the neutralization of free-heme and its transport to the liver. In this study, we isolated and characterized the two isoforms of wap65 genes (Ccwap65-1 and Ccwap65-2) from the liver of milkfish. The Ccwap65-1 and Ccwap65-2 are mainly expressed in livers of milkfish. In hypothermal treatment, the expression levels of Ccwap65-2 in the livers of SW and FW milkfish were up-regulated after exposure to low temperature (18 °C) for 12 h and 96 h compared to those in the normal temperature (28 °C) group, respectively. After intraperitoneal injection of lipopolysaccharide (LPS), the expression of Ccwap65-2 was elevated in both SW and FW milkfish, whereas that of Ccwap65-1 was not affected in both the groups. Thus, Ccwap65-2 expressed in the milkfish liver under hypothermal stress was identified as a novel immune biomarker. In addition, according to the transcriptome database, up-regulation of the other immune-response genes indicated increased pathogen infection status under hypothermal stress. Acute increase in the expression of hepatic Ccwap65-2 in response to pathogen infection might lead to better cold tolerance of SW milkfish compared to that of the FW individuals upon cold challenge.

Nutritional Immunity Triggers the Modulation of Iron Metabolism Genes in the Sub-Antarctic Notothenioid Eleginops maclovinus in Response to Piscirickettsia salmonis

Iron deprivation is a nutritional immunity mechanism through which fish can limit the amount of iron available to invading bacteria. The aim of this study was to evaluate the modulation of iron metabolism genes in the liver and brain of sub-Antarctic notothenioid Eleginops maclovinus challenged with Piscirickettsia salmonis. The specimens were inoculated with two P. salmonis strains: LF-89 (ATCC^® VR-1361™) and Austral-005 (antibiotic resistant). Hepatic and brain samples were collected at intervals over a period of 35 days. Gene expression (by RT-qPCR) of proteins involved in iron storage, transport, and binding were statistically modulated in infected fish when compared with control counterparts. Specifically, the expression profiles of the transferrin and hemopexin genes in the liver, as well as the expression profiles of ferritin-M, ferritin-L, and transferrin in the brain, were similar for both experimental groups. Nevertheless, the remaining genes such as ferritin-H, ceruloplasmin, hepcidin, and haptoglobin presented tissue-specific expression profiles that varied in relation to the injected bacterial strain and sampling time-point. These results suggest that nutritional immunity could be an important immune defense mechanism for E. maclovinus against P. salmonis injection. This study provides relevant information for understanding iron metabolism of a sub-Antarctic notothenioid fish.

PLASMA PROTEIN ELECTROPHORESIS AND SELECT ACUTE PHASE PROTEINS IN HEALTHY BONNETHEAD SHARKS (SPHYRNA TIBURO) UNDER MANAGED CARE

Preventative health care of elasmobranchs is an important but understudied field of aquatic veterinary medicine. Evaluation of inflammation through the acute phase response is a valuable tool in health assessments. To better assess the health of bonnethead sharks ( Sphyrna tiburo ) under managed care, normal reference intervals of protein electrophoresis (EPH) and the acute phase proteins, C-reactive protein (CRP) and haptoglobin (HP), were established. Blood was collected from wild caught, captive raised bonnethead sharks housed at public aquaria. Lithium heparinized plasma was either submitted fresh or stored at -80°C prior to submission. Electrophoresis identified protein fractions with migration characteristics similar to other animals with albumin, α-1 globulin, α-2 globulin, β globulin, and γ globulin. These fractions were classified as fractions 1-5 as fractional contents are unknown in this species. Commercial reagents for CRP and HP were validated for use in bonnethead sharks. Reference intervals were established using the robust method recommended by the American Society for Veterinary Clinical Pathology for the calculation of 90% reference intervals. Once established, the diagnostic and clinical applicability of these reference intervals was used to assess blood from individuals with known infectious diseases that resulted in systemic inflammation and eventual death. Unhealthy bonnethead sharks had significantly decreased fraction 2, fraction 3, and fraction 3:4 ratio and significantly increased fraction 5, CRP, and HP. These findings advance our understanding of elasmobranch acute phase inflammatory response and health and aid clinicians in the diagnosis of inflammatory disease in bonnethead sharks.

Dietary Yeast Cell Wall Extract Alters the Proteome of the Skin Mucous Barrier in Atlantic Salmon (Salmo salar): Increased Abundance and Expression of a Calreticulin-Like Protein

In order to improve fish health and reduce use of chemotherapeutants in aquaculture production, the immunomodulatory effect of various nutritional ingredients has been explored. In salmon, there is evidence that functional feeds can reduce the abundance of sea lice. This study aimed to determine if there were consistent changes in the skin mucus proteome that could serve as a biomarker for dietary yeast cell wall extract. The effect of dietary yeast cell wall extract on the skin mucus proteome of Atlantic salmon was examined using two-dimensional gel electrophoresis. Forty-nine spots showed a statistically significant change in their normalised volumes between the control and yeast cell wall diets. Thirteen spots were successfully identified by peptide fragment fingerprinting and LC-MS/MS and these belonged to a variety of functions and pathways. To assess the validity of the results from the proteome approach, the gene expression of a selection of these proteins was studied in skin mRNA from two different independent feeding trials using yeast cell wall extracts. A calreticulin-like protein increased in abundance at both the protein and transcript level in response to dietary yeast cell wall extract. The calreticulin-like protein was identified as a possible biomarker for yeast-derived functional feeds since it showed the most consistent change in expression in both the mucus proteome and skin transcriptome. The discovery of such a biomarker is expected to quicken the pace of research in the application of yeast cell wall extracts.

Identification of a C-reactive protein like homologue from black rockfish (Sebastes schlegelii) evidencing its potent anti-microbial properties at molecular level

Pentraxins are a family of evolutionary conserved proteins that contains two main members, namely c-reactive proteins (CRPs) and serum amyloid P (SAP), which are involved in acute phase responses in animals. In this study, a cDNA sequence of a CRP-like molecule was identified from a previously constructed black rockfish cDNA database (RfCRP) and subsequently characterized at its molecular level. The complete coding region of RfCRP is 672 bp in length, and encodes a protein containing 224 amino acids with a predicted molecular mass of 25.19 kDa. Analysis of its derived amino acid sequence enabled typical features of pentraxin family members to be identified, including the pentraxin family signature in RfCRP. Results from multiple sequence alignment suggest the conservation of functionally important residues in RfCRP. According to the phylogenetic reconstruction that was generated using different pentraxin counterparts from different taxa, RfCRP shares a common vertebrate ancestral origin and most closely clusters with marine teleostan CRP. Furthermore, recombinant RfCRP demonstrated Ca(2+)-dependent agglutination activity against Escherichia coli, which could be completely inhibited in the presence of carbohydrate based ligands. Moreover, recombinant RfCRP also exhibited anti-bacterial activity against both E. coli and Streptococcus iniae. In addition, qPCR analysis indicated that RfCRP is ubiquitously expressed in physiologically important tissues, with pronounced expression in the spleen. After healthy fish were treated with polysaccharides or live S. iniae, basal expression of RfCRP was significantly upregulated in spleen and head kidney tissues. Collectively, our results suggest that RfCRP may be important in host anti-bacterial defense, and it might potentially participate in the acute phase of infection.

What the shark immune system can and cannot provide for the expanding design landscape of immunotherapy

INTRODUCTION

Sharks have successfully lived in marine ecosystems, often atop food chains as apex predators, for nearly one and a half billion years. Throughout this period they have benefitted from an immune system with the same fundamental components found in terrestrial vertebrates like man. Additionally, sharks have some rather extraordinary immune mechanisms which mammals lack.

AREAS COVERED

In this review the author briefly orients the reader to sharks, their adaptive immunity, and their important phylogenetic position in comparative immunology. The author also differentiates some of the myths from facts concerning these animals, their cartilage, and cancer. From thereon, the author explores some of the more remarkable capabilities and products of shark lymphocytes. Sharks have an isotype of light chain-less antibodies that are useful tools in molecular biology and are moving towards translational use in the clinic. These special antibodies are just one of the several tricks of shark lymphocyte antigen receptor systems.

EXPERT OPINION

While shark cartilage has not helped oncology patients, shark immunoglobulins and T cell receptors do offer exciting novel possibilities for immunotherapeutics. Much of the clinical immunology developmental pipeline has turned from traditional vaccines to passively delivered monoclonal antibody-based drugs for targeted depletion, activation, blocking and immunomodulation. The immunogenetic tools of shark lymphocytes, battle-tested since the dawn of our adaptive immune system, are well poised to expand the design landscape for the next generation of immunotherapy products.

Genomic organization and functional diversification of two warm-temperature-acclimation-associated 65-kDa protein genes in rockbream (Oplegnathus fasciatus; Perciformes)

Two paralogue genes of warm-temperature-acclimation-associated 65-kDa protein were characterized and their mRNA expression patterns during various experimental stimulations were examined in the rockbream (Oplegnathus fasciatus; Perciformes). Rockbream Wap65 isoforms (rbWap65-1 and rbWap65-2) share basically common structural features with other teleostean orthologues and human hemopexin (HPX) at both amino acid (conserved cysteine and histidine residues) and genomic levels (ten-exon structure), although the rbWap65-2 reveals more homologous characteristics to human HPX than does rbWap65-1 isoform. Southern blot analysis indicates that each rbWap65 isoform exists as a single copy gene in the rockbream genome. Both rbWap65 genes were predicted to possess various transcription factor (TF) binding motifs related with stress and innate immunity in their 5ʹ-upstream regions, in which inflammation-related motifs were more highlighted in the rbWap65-2 than in rbWap65-1. Based on the RT-PCR assay, the liver-predominant expression pattern was more apparent in rbWap65-1 than rbWap65-2 isoform. During thermal elevation, clear upregulation was found only for the rbWap65-1. In contrast, immune stimulations (bacterial challenges, viral infection and iron overload) activated more preferentially the rbWap65-2 isoform in overall, although the inducibility was affected by the kinds of stimulators and tissue types. Taken together, our data suggest that the two paralogue rbWap65 isoforms have experienced subfunctionalization and/or neofunctionalization during their evolutionary history, in which the rbWap65-2 has retained closer, functional orthology to the human HPX while the rbWap65-1 have been diversified to be more related with thermal acclimation physiology.

Adaptive functional divergence of the warm temperature acclimation-related protein (WAP65) in fishes and the ortholog hemopexin (HPX) in mammals

Gene duplication is an important mechanism that leads to genetic novelty. Different, nonexclusive processes are likely involved, and many adaptive and nonadaptive events may contribute to the maintenance of duplicated genes. In some teleosts, a duplicate copy of the mammalian ortholog Hemopexin (HPX) is present, known as the warm temperature acclimation-related protein (WAP65). Both WAP65 and HPX have been associated with iron homeostasis due to the affinity to bind the toxic-free heme circulating in the blood stream. We have assessed the evolutionary dynamics of WAP65 and HPX genes to understand the adaptive role of positive selection at both nucleotide and amino acid level. Our results showed an asymmetrical evolution between the paralogs WAP65-1 and WAP65-2 after duplication with a slight acceleration of the evolutionary rate in WAP65-1, but not in WAP65-2, and few sites contributing to the functional distinction between the paralogs, whereas the majority of the protein remained under negative selection or relaxed negative selection. WAP65-1 is functionally more distinct from the ancestral protein function than WAP65-2. HPX is phylogenetically closer to WAP65-2 but even so functional divergence was detected between both proteins. In addition, HPX showed a fast rate of evolution when compared with both WAP65-1 and WAP65-2 genes. The assessed 3-dimensional (3-D) structure of WAP65-1 and WAP65-2 suggests that the functional differences detected are not causing noticeable structural changes in these proteins. However, such subtle changes between WAP65 paralogs may be important to understand the differential gene retention of both copies in 20 out of 30 teleosts species studied.

Genetic organization of two types of flounder warm-temperature acclimation-associated 65-kDa protein and their gene expression profiles

We isolated and characterized two cDNA clone encoding warm-temperature acclimation-associated 65-kDa proteins (PoWap65-1 and PoWap65-2) from the olive flounder, Paralichthys olivaceus. The deduced amino acid sequences of PoWap65s showed overall identities of 33-73% with other fish Wap65 and mammalian hemopexin-like proteins. The 5'-flanking regions of both PoWap65-encoding genes contained various putative transcriptional elements. While PoWap65-1 and PoWap65-2 were structurally similar, they exhibited highly differential patterns of expression. PoWap65-1 was expressed only in the liver, whereas PoWap65-2 transcripts were detected in a wide range of tissues. The accumulation of PoWap65s mRNA was expressed differentially during development. Expression of them in warm temperatures also differed in flounder embryonic cells. PoWap65-1 was upregulated by temperature stimulation whereas PoWap65-2 was not detected. PoWap65s were highly regulated by Edwardsiella tarda infection and hypoxia. Pathogen challenge induced PoWap65-2 expression in the liver whereas PoWap65-1 was downregulated. Hypoxia induced the expression of both PoWap65s in the liver of juvenile fish.

Proteomic characterization of the acute-phase response of yellow stingrays Urobatis jamaicensis after injection with a Vibrio anguillarum-ordalii bacterin

Systemic inflammatory responses of mammals and bony fish are primarily driven by coordinated up-regulation and down-regulation of plasma acute-phase proteins. Although this general principle is believed to be universal among vertebrates, it remains relatively unexplored in elasmobranchs. The objective of this study was to characterize acute changes in the plasma proteome of three yellow stingrays Urobatis jamaicensis following intraperitoneal injection with a commercial Vibrio bacterin. Changes in plasma protein levels were analyzed immediately prior to vaccination (time 0) and at 24 and 72 h post-injection by isobaric tags for relative and absolute quantitation (iTRAQ 4-plex) using shotgun-based nano liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and de novo peptide sequencing. Pooled 2D-LC-MS/MS and de novo sequencing data revealed differential expression of 156 distinct plasma proteins between time 0 and at least one post-vaccination time point. Using 1.5-fold change in expression as physiologically significant, 14/156 (9.0%) proteins were upregulated in at least one stingray through at least one experimental timepoint. Upregulated proteins included complement factors, Mx-protein, hemopexin, factor X and prothrombin. Seventy-six of 156 (48.7%) proteins were downregulated in the acute-phase response, including transferrin, apolipoprotein B, heparin cofactor 2, alpha2-macroglobulin, and various growth factors. Other differentially upregulated or downregulated proteins included intracellular, cell binding and structural proteins, proteins involved in physiologic processes, and unknown/hypothetical proteins. Selected bioactive factors are discussed for their putative roles in the elasmobranchs acute-phase response. These findings contribute to our understanding of disease processes in elasmobranchs, immunologic phylogeny in vertebrates, and begin the search for potential biomarkers of disease in these ecologically important fish.

Physiological and proteomic responses to single and repeated hypoxia in juvenile Eurasian perch under domestication--clues to physiological acclimation and humoral immune modulations

We evaluated the physiological and humoral immune responses of Eurasian perch submitted to 4-h hypoxia in either single or repeated way. Two generations (F1 and F5) were tested to study the potential changes in these responses with domestication. In both generations, single and repeated hypoxia resulted in hyperglycemia and spleen somatic index reduction. Glucose elevation and lysozyme activity decreased following repeated hypoxia. Complement hemolytic activity was unchanged regardless of hypoxic stress or domestication level. A 2D-DIGE proteomic analysis showed that some C3 components were positively modulated by single hypoxia while C3 up- and down-regulations and over-expression of transferrin were observed following repeated hypoxia. Domestication was associated with a low divergence in stress and immune responses to hypoxia but was accompanied by various changes in the abundance of serum proteins related to innate/specific immunity and acute phase response. Thus, it appeared that the humoral immune system was modulated following single and repeated hypoxia (independently of generational level) or during domestication and that Eurasian perch may display physiological acclimation to frequent hypoxic disturbances.

Modulation of warm-temperature-acclimation-associated 65-kDa protein genes (Wap65-1 and Wap65-2) in mud loach (Misgurnus mizolepis, Cypriniformes) liver in response to different stimulatory treatments

Two paralogous isoform cDNAs of warm-temperature-acclimation-associated 65-kDa protein (Wap65-1 and Wap65-2) were isolated from the cypriniform species, mud loach (Misgurnus mizolepis), and characterized. The deduced amino acid sequences of the two mud loach Wap65 isoforms (mlWap65-1 and mlWap65-2) share moderate levels of sequence homology with their corresponding orthologues from teleosts and with human hemopexin, a possible mammalian homologue. Both isoforms display conserved features, including essential motifs and/or residues that are important for the protein structure of hemopexin. In overall, mlWap65-2 is more homologous to human hemopexin than is mlWap65-1. Both mud loach Wap65 transcripts are predominantly expressed in liver, although the transcripts are ubiquitously detectable in most tissues with variable basal expression. Both mlWap65 isoforms are differentially regulated during embryonic development, and the changes in transcript levels during embryogenesis are greater for mlWap65-2 than for mlWap65-1. The transcription of the mlWap65 genes is differentially modulated by various stimuli, including thermal changes, immune challenge (lipopolysaccharide injection or bacterial infection), and heavy metal exposure (cadmium, copper, or nickel). The isoform mlWap65-1 is more responsive to warm temperature treatments than mlWap65-2, whereas mlWap65-2 is much more strongly stimulated by immune and heavy metal challenges than is mlWap65-1. Taken together, the results of this study suggest that mud loach Wap65 isoforms are potentially involved in multiple cellular pathways and that the two mud loach Wap65 isoforms undergo functional partitioning or subfunctionalization.