Impact of ocean acidification on antimicrobial activity in gills of the blue mussel (Mytilus edulis)

The molecular response of Mytilus coruscus mantle to shell damage under acute acidified sea water revealed by iTRAQ based quantitative proteomic analysis

Mytilus coruscus is an economically important marine bivalve that lives in estuarine sea areas with seasonal coastal acidification and frequently suffers shell injury in the natural environment. However, the molecular responses and biochemical properties of Mytilus under these conditions are not fully understood. In the present study, we employed tandem mass spectrometry combined with isobaric tagging to identify differentially expressed proteins in the mantle tissue of M. coruscus under different short-term treatments, including shell-complete mussels raised in normal seawater (pH 8.1), shell-damaged mussels raised in normal seawater (pH 8.1), and acidified seawater (pH 7.4). A total of 2694 proteins were identified in the mantle, and analysis of their relative abundance from the three different treatments revealed alterations in the proteins involved in immune regulation, oxidation-reduction processes, protein folding and processing, energy provision, and cytoskeleton. The results obtained by quantitative proteomic analysis of the mantle allowed us to delineate the molecular strategies adopted by M. coruscus in the shell repair process in acidified environments, including an increase in proteins involved in oxidation-reduction processes, protein processing, and cell growth at the expense of proteins involved in immune capacity and energy metabolism. SIGNIFICANCE: The impact of global ocean acidification on calcifying organisms has become a major ecological and environmental problem in the world. Mytilus coruscus is an economically important marine bivalve living in estuary sea area with seasonal coastal acidification, and frequently suffering shell injury in natural environment. Molecular responses of M coruscus under the shell damage and acute acidification is still largely unknown. For this reason, iTRAQ based quantitative proteomic and histological analysis of the mantle from M. coruscus under shell damage and acute acidification were performed, for revealing the proteomic response and possible adaptation mechanism of Mytilus under combined shell damage and acidified sea water, and understanding how the mussel mantle implement a shell-repair process under acidified sea water. Our study provides important data for understanding the shell repair process and proteomic response of Mytilus under ocean acidification, and providing insights into potential adaptation of mussels to future global change.

Addressing the Joint Impact of Temperature and pH on Vibrio harveyi Adaptation in the Time of Climate Change

Global warming and acidification of the global ocean are two important manifestations of the ongoing climate change. To characterize their joint impact on Vibrio adaptation and fitness, we analyzed the temperature-dependent adaptation of Vibrio harveyi at different pHs (7.0, 7.5, 8.0, 8.3 and 8.5) that mimic the pH of the world ocean in the past, present and future. Comparison of V. harveyi growth at 20, 25 and 30 °C show that higher temperature per se facilitates the logarithmic growth of V. harveyi in nutrient-rich environments in a pH-dependent manner. Further survival tests carried out in artificial seawater for 35 days revealed that cell culturability declined significantly upon incubation at 25 °C and 30 °C but not at 20 °C. Moreover, although acidification displayed a negative impact on cell culturability at 25 °C, it appeared to play a minor role at 30 °C, suggesting that elevated temperature, rather than pH, was the key player in the observed reduction of cell culturability. In addition, analyses of the stressed cell morphology and size distribution by epifluorescent microscopy indicates that V. harveyi likely exploits different adaptation strategies (e.g., acquisition of coccoid-like morphology) whose roles might differ depending on the temperature-pH combination.

Pathogens transported by plastic debris: does this vector pose a risk to aquatic organisms?

Microplastics are small (<5 mm) plastic particles of varying shapes and polymer types that are now widespread global contaminants of marine and freshwater ecosystems. Various estimates suggest that several trillions of microplastic particles are present in our global oceanic system, and that these are readily ingested by a wide range of marine and freshwater species across feeding modes and ecological niches. Here, we present some of the key and pressing issues associated with these globally important contaminants from a microbiological perspective. We discuss the potential mechanisms of pathogen attachment to plastic surfaces. We then describe the ability of pathogens (both human and animal) to form biofilms on microplastics, as well as dispersal of these bacteria, which might lead to their uptake into aquatic species ingesting microplastic particles. Finally, we discuss the role of a changing oceanic system on the potential of microplastic-associated pathogens to cause various disease outcomes using numerous case studies. We set out some key and imperative research questions regarding this globally important issue and present a methodological framework to study how and why plastic-associated pathogens should be addressed.

Identification, characterization and expression analyses of PC4 genes in Yesso scallop (Patinopecten yessoensis) reveal functional differentiations in response to ocean acidification

Transcriptional coactivator p15 (PC4), considered a multifunctional chromosome associated protein, is actively involved in transcription regulation, DNA replication, damage repair and chromosome formation. Although studies have reported significant effects of PC4 in most vertebrates and some invertebrates, the complete PC4 gene members are less systematically identified and characterized in scallops. In this study, seven PC4 genes (PyPC4s) were identified in the Yesso scallop Patinopecten yessoensis using whole-genome scanning via bioinformatic analyses. Phylogenetic and protein structural analyses were performed to determine the identities and evolutionary relationships of the seven genes. Expression profiles of PyPC4s were further investigated in embryos/larvae at all developmental stages, healthy adult tissues, and mantles that were exposed to low pH stress (pH 6.5 and 7.5) with different time durations (3, 6, 12 and 24 h). Spatiotemporal expression patterns indicated the functional roles of PyPC4s at all development stages and in healthy adult tissues, with PY-3235.33 demonstrating remarkably high constitutive expressions. Expression regulations (up- and down-regulation) of PyPC4s under low pH stress levels demonstrated a time-dependent pattern with functional complementation and/or enhancement, revealing that PyPC4s exhibited differentiated functions in response to ocean acidification (OA). Collectively, our data offer a novel perspective stating that low pH is a potential inducer leading to functional differentiation of PyPC4s in scallops. The results provide preliminary information on the versatile roles of PC4(s) in bivalves in response to OA.

Biological effects of the antihypertensive losartan under different ocean acidification scenarios

Since the last decade, several studies have reported the presence and effects of pharmaceutical residues in the marine environment, especially those of the antihypertensive class, such as losartan. However, there is little knowledge about the physiological effects of losartan in marine invertebrates regarding its behavior under possible coastal ocean acidification scenarios. The objective of this study was to evaluate biological effects on marine organisms at different levels of the biological organization caused by the compound losartan in water and sediment under coastal ocean acidification scenarios. Water and sediment samples were collected at five sites around the Santos Submarine Sewage outfall (SSO) and two sites around the Guarujá Submarine Sewage Outfall (GSO). Losartan was found in concentrations ranging from <LOD to 7.63 ng/L in water and from <LOQ to 3.10 ng/g in sediments. Statistical analysis showed interactive effects pH and losartan on the toxicity results. The water toxicity test with Echinometra lucunter embryos/larvae showed LOECs 50-100 mg/L, with values decreasing as the pH decreased. In the sediment assays, LOEC value for sea urchin embryo-larval development was 1.0 μg/g for all tested pHs. Regarding the lysosomal membrane stability assays with adult bivalves, a LOEC of 3000 ng/L was found for Perna perna in water exposure (both at pH 8.0 and 7.6). Effects for Mytella guyanensis were observed at environmentally relevant concentrations in sediment (LOEC = 3 ng/g at pH 8.0 and 7.6). This study demonstrated that coastal ocean acidification by itself causes effects on marine invertebrates, but can also increase the negative effects of losartan in waterborne exposure. There is a need to deepen the studies on the ecotoxicity of pharmaceutical residues and acidification of the marine environment.

In vitro effects of erythromycin and florfenicol on primary cell lines of Unio crassus and Cyprinus carpio

The ubiquitous use of antibiotics leads exposure of these chemicals on non-target aquatic species, while the toxicity assays for these chemicals are time/labor consuming and expensive. Alternative approaches using primary cell cultures which retain the tissue functionality at its highest form have received global attention compared to cell lines. In the current study, the cytotoxic effects of two commonly used antibiotics from amphenicol (florfenicol) and macrolide (erythromycin) groups were evaluated on primary cell cultures of Unio crassus (mantle, digestive gland, gill, and gonad) and Cyprinus carpio (gill and liver) using MTT and Neutral Red assays. The highest cytotoxic effects were found on the mussel digestive gland and carp liver cells for florfenicol and erythromycin, while the lowest cytotoxic effects were found in mussel mantle cells for both drugs in the MTT test. In the NR test, the highest cytotoxic effects of erythromycin and florfenicol were found in the mussel gill, mantle, gonad, and carp gill cells; the lowest cytotoxic effect of erythromycin was found in the mussel digestive gland, while the lowest effect of florfenicol was found in the carp liver cells. The cytotoxicity of florfenicol was quite low for the carp liver, while the cytotoxicity of erythromycin was quite low in the mussel digestive tract. Thus, it was concluded that cells made from mussel tissues could be used in ecotoxicity tests, and sensitivity may vary according to the tissue.

Immunosuppression of aquatic organisms exposed to elevated levels of manganese: From global to molecular perspective

Manganese (Mn) is an essential trace metal for all organisms. However, in excess it causes toxic effects but the impact on aquatic environments has so far been highly overlooked. Manganese is abundant both in costal and deep sea sediments and becomes bioavailable (Mn²⁺) during redox conditions. This is an increasing phenomenon due to eutrophication-induced hypoxia and aggravated through the ongoing climate change. Intracellular accumulation of Mn²⁺ causes oxidative stress and activates evolutionary conserved pathways inducing apoptosis and cell cycle arrest. Here, studies are compiled on how excess of dissolved Mn suppresses the immune system of various aquatic organisms by adversely affecting both renewal of immunocytes and their functionality, such as phagocytosis and activation of pro-phenoloxidase. These impairments decrease the animal's bacteriostatic capacity, indicating higher susceptibility to infections. Increased distribution of pathogens, which is believed to accompany climate change, requires preserved immune sentinel functions and Mn can be crucial for the outcome of host-pathogen interactions.

Experimental evaluation of survival of Vibrio parahaemolyticus in fertilized cold-water sediment

AIMS

This experimental study focuses on survival and consistence of Vibrio parahaemolyticus in cold-water sediments and how increasing temperature and nutritional availability can affect growth.

METHODS AND RESULTS

A pathogenic strain of V. parahaemolyticus was inoculated in seawater microcosms containing bottom sediment. Gradually, during 14 days, the temperature was upregulated from 8 to 21°C. Culturable V. parahaemolyticus was only found in the sediment but declined over time and did not recover even after another 2 days at 37°C. Numbers of culturable bacteria matched the amount found by q-PCR indicating that they did not enter a dormant state, contrary to those in the water layer. After adding decaying phytoplankton as fertilizer to the microcosms of 8 and 21°C for 7 and 14 days, the culturability of the bacteria increased significantly in the sediments at both temperatures and durations of exposure.

CONCLUSION

The study showed that V. parahaemolyticus can stay viable in cold-water sediment and growth was stimulated by fertilizers rather than by temperature.

SIGNIFICANCE AND IMPACT OF THE STUDY

Vibrio parahaemolyticus is a common cause of seafood-borne gastroenteritis and is today recognized in connection to increasing ocean temperature. The results indicate that this pathogen should be considered a risk in well-fertilized environments, such as aquacultures, even during cold periods.

Ocean acidification and adaptive bivalve farming

Multiple lines of evidence, ranging from time series field observations to climate change stimulation experiments demonstrate the negative effects of global warming and ocean acidification (OA) on bivalve molluscs. The impact of global warming on bivalve aquaculture has recently been reviewed. However, the impact of OA on bivalve aquaculture has received relatively less attention. Although there are many reports on the effects of OA on bivalves, this information is poorly organized and the connection between OA and bivalve aquaculture is unclear. Therefore, understanding the potential impact of acidification on ecosystems and bivalve aquaculture is of prime importance. Here, we provide a comprehensive scientific review of the impact of OA on bivalves and propose mitigation measures for future bivalve farming. This information will help to establish aquaculture and fisheries management plans to be implemented in commercial fisheries and nature conservation. In general, scientific evidence suggests that OA threatens bivalves by diminishing the availability of carbonate minerals, which may adversely affect the development of early life stages, calcification, growth, byssus attachment and survival of bivalves. The Integrated multi-trophic aquaculture (IMTA) approach is a useful method in slowing the effects of climate change, thereby providing longer adaptation period for bivalves to changing ocean conditions. However, for certain regions that experience intense OA effects or for certain bivalve species that have much longer generational time, IMTA alone may not be sufficient to protect bivalves from the adverse effects of climate change. Therefore, it is highly recommended to combine IMTA and genetic breeding methods to facilitate transgenerational acclimation or evolution processes to enhance the climate resilience of bivalves.

Separation, identification and gene expression analysis of PmAMP-1 from Pinctada fucata martensii

Antibacterial peptides (AMPs) constitute an important part of the body's innate immune system and are responsible for a wide range of inhibitory effects against pathogens such as bacteria, fungi, and viruses. In this study, multi-step high performance liquid chromatography (HPLC), combined with Mass Spectrometry (MS), was used to isolate and identify proteins with antibacterial activity from the serum of Pinctada fucata martensii (P.f. Martensii) and obtain a component named P.f. Martensii antimicrobial peptide-1 (PmAMP-1). PmAMP-1 cDNA was cloned and sequenced by rapid amplification of cDNA ends (RACE) and mRNA expression of was analyzed by quantitative real-time PCR (qRT-PCR). From the results of this study, full-length PmAMP-1 cDNA was shown to be 700 base pairs (bp) long with an open reading frame (ORF) of 294 bp, encoding 97 amino acids with a predicted structure that is mostly α-helices. PmAMP-1 mRNA was constitutively expressed in all tested tissues including the adductor muscle, mantle, hepatopancreas, gill, gonads and hemocytes. The highest level of PmAMP-1 transcription was observed at 8 h and 2 h after bacterial challenge in hemocytes and adductor muscle (p < 0.01), respectively. Furthermore, PmAMP-1 caused significant morphological alterations in E. coli, as shown by transmission electron microscopy (TEM). The results from this study provide a valuable base for further exploration of molluscan innate immunity and immune response.

Distribution of three isoforms of antimicrobial peptide, chrysophsin-1, -2 and -3, in the red sea bream, Pagrus (Chrysophrys) major

We report here a liquid chromatography/electrospray ionization-tandem mass spectrometry assay for the quantification of three isoforms of antimicrobial peptide (AMP), chrysophsin-1, -2 and -3, in the red sea bream, Pagrus (Chrysophrys) major. Chrysophsin-1 was mainly distributed in the pyloric caeca and gills, followed by intestine and stomach. Chrysophsin-2 was detected in the gills and stomach, but chrysophsin-3 was only in the gills. The present procedure is valuable as a general method for simultaneous determination of the level of multiple AMP isoforms in fish tissues, and the data give important information for understanding the significance of each AMP isoform in host defense.

Identification and In Silico Prediction of Anticoagulant Peptides from the Enzymatic Hydrolysates of Mytilus edulis Proteins

Mytilus edulis is a typical marine bivalve mollusk. Many kinds of bioactive components with nutritional and pharmaceutical activities in Mytilus edulis were reported. In this study, eight different parts of Mytilus edulis tissues, i.e., the foot, byssus, pedal retractor muscle, mantle, gill, adductor muscle, viscera, and other parts, were separated and the proteins from these tissues were prepared. A total of 277 unique peptides from the hydrolysates of different proteins were identified by UPLC-Q-TOF-MS/MS, and the molecular weight distribution of the peptides in different tissues was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The bioactivity of the peptides was predicted through the Peptide Ranker database and molecular docking. Moreover, the peptides from the adductor muscle were chosen to do the active validation of anticoagulant activity. The active mechanism of three peptides from the adductor muscle, VQQELEDAEERADSAEGSLQK, RMEADIAAMQSDLDDALNGQR, and AAFLLGVNSNDLLK, were analyzed by Discovery Studio 2017, which also explained the anticoagulant activity of the hydrolysates of proteins from adductor muscle. This study optimized a screening and identification method of bioactive peptides from enzymatic hydrolysates of different tissues in Mytilus edulis.

Seawater Acidification Reduced the Resistance of Crassostrea gigas to Vibrio splendidus Challenge: An Energy Metabolism Perspective

Negative physiological impacts induced by exposure to acidified seawater might sensitize marine organisms to future environmental stressors, such as disease outbreak. The goal of this study was to evaluate if ocean acidification (OA) could reduce the resistance capability of the Pacific oyster (Crassostrea gigas) to Vibrio splendidus challenge from an energy metabolism perspective. In this study, the Pacific oyster was exposed to OA (pH 7.6) for 28 days and then challenged by V. splendidus for another 72 h. Antioxidative responses, lipid peroxidation, metabolic (energy sensors, aerobic metabolism, and anaerobic metabolism) gene expression, glycolytic enzyme activity, and the content of energy reserves (glycogen and protein) were investigated to evaluate the environmental risk of pathogen infection under the condition of OA. Our results demonstrated that following the exposure to seawater acidification, oysters exhibited an energy modulation with slight inhibition of aerobic energy metabolism, stimulation of anaerobic metabolism, and increased glycolytic enzyme activity. However, the energy modulation ability and antioxidative regulation of oysters exposed to seawater acidification may be overwhelmed by a subsequent pathogen challenge, resulting in increased oxidative damage, decreased aerobic metabolism, stimulated anaerobic metabolism, and decreased energy reserves. Overall, although anaerobic metabolism was initiated to partially compensate for inhibited aerobic energy metabolism, increased oxidative damage combined with depleted energy reserves suggested that oysters were in an unsustainable bioenergetic state and were thereby incapable of supporting long-term population viability under conditions of seawater acidification and a pathogen challenge from V. splendidus.

Alterations in haemolymph proteome of Mytilus galloprovincialis mussel after an induced injury

A proteomic and biochemical approach was performed to assess the effects of an induced muscle injury on the haemolymph of bivalve molluscs. For this purpose, Mytilus galloprovincialis were exposed to puncture of adductor muscle for three consecutive days, and their haemolymph proteome was then compared to healthy animals using 2-dimensional electrophoresis (2-DE) to identify proteins that differed significantly in abundance. Those proteins were then subjected to tandem mass spectrometry and 6 proteins, namely myosin, tropomyosin, CuZn superoxide dismutase (SOD), triosephosphate isomerase, EP protein and small heat shock protein were identified. SOD and tropomyosin changes were verified by spectrophotometric measurements and western blotting, respectively. As some of the proteins identified are related to muscular damage and oxidative stress, other biomarkers associated with these processes that can be evaluated by automatic biochemical assays were measured including troponin, creatine kinase (CK), and aspartate aminotransferase (AST) for muscle damage, and SOD, trolox equivalent antioxidant capacity (TEAC) and esterase activity (EA) for oxidative stress. Significantly higher concentrations of troponin, CK, AST, and TEAC were observed in mussels after puncture, being also possible biomarkers of non-specific induced damage.

Oxidative and interactive challenge of cadmium and ocean acidification on the smooth scallop Flexopecten glaber

Ocean acidification (OA) may affect sensitivity of marine organisms to metal pollution modulating chemical bioavailability, bioaccumulation and biological responsiveness of several cellular pathways. In this study, the smooth scallop Flexopecten glaber was exposed to various combinations of reduced pH (pH/pCO₂ 7.4/∼3000 μatm) and Cd (20 μg/L). The analyses on cadmium uptake were integrated with those of a wide battery of biomarkers including metallothioneins, single antioxidant defenses and total oxyradical scavenging capacity in digestive gland and gills, lysosomal membrane stability and onset of genotoxic damage in haemocytes. Reduced pH slightly increased concentration of Cd in scallop tissues, but no effects were measured in terms of metallothioneins. Induction of some antioxidants by Cd and/or low pH in the digestive gland was not reflected in variations of the total oxyradical scavenging capacity, while the investigated stressors caused a certain inhibition of antioxidants and reduction of the scavenging capacity toward peroxyl radical in the gills. Lysosomal membrane stability and onset of genotoxic damages showed high sensitivity with possible synergistic effects of the investigated factors. The overall results suggest that indirect effects of ocean acidification on metal accumulation and toxicity are tissue-specific and modulate oxidative balance through different mechanisms.

Alteration of host-pathogen interactions in the wake of climate change - Increasing risk for shellfish associated infections?

The potential for climate-related spread of infectious diseases through marine systems has been highlighted in several reports. With this review we want to draw attention to less recognized mechanisms behind vector-borne transmission pathways to humans. We have focused on how the immune systems of edible marine shellfish, the blue mussels and Norway lobsters, are affected by climate related environmental stressors. Future ocean acidification (OA) and warming due to climate change constitute a gradually increasing persistent stress with negative trade-off for many organisms. In addition, the stress of recurrent hypoxia, inducing high levels of bioavailable manganese (Mn) is likely to increase in line with climate change. We summarized that OA, hypoxia and elevated levels of Mn did have an overall negative effect on immunity, in some cases also with synergistic effects. On the other hand, moderate increase in temperature seems to have a stimulating effect on antimicrobial activity and may in a future warming scenario counteract the negative effects. However, rising sea surface temperature and climate events causing high land run-off promote the abundance of naturally occurring pathogenic Vibrio and will in addition, bring enteric pathogens which are circulating in society into coastal waters. Moreover, the observed impairments of the immune defense enhance the persistence and occurrence of pathogens in shellfish. This may increase the risk for direct transmission of pathogens to consumers. It is thus essential that in the wake of climate change, sanitary control of coastal waters and seafood must recognize and adapt to the expected alteration of host-pathogen interactions.

Ocean acidification and pathogen exposure modulate the immune response of the edible mussel Mytilus chilensis

Ocean acidification (OA) is one of the main consequences of increasing atmospheric carbon dioxide (CO₂), impacting key biological processes of marine organisms such as development, growth and immune response. However, there are scarce studies on the influence of OA on marine invertebrates' ability to cope with pathogens. This study evaluated the single and combined effects of OA and bacterial infection on the transcription expression of genes related to antioxidant system, antimicrobial peptides and pattern recognition receptors in the edible mussel Mytilus chilensis. Individuals of M. chilensis were exposed during 60 days at two concentrations of pCO₂ (550 and 1200 μatm) representing respectively current and future scenario of OA and were then injected with the pathogenic bacterium Vibrio anguillarum. Results evidenced an immunomodulation following the OA exposure with an up-regulation of C-type Lectin and Mytilin B and a down-regulation of Myticin A and PGRP. This immunomodulation pattern is partially counteracted after challenge with V. anguillarum with a down-regulation of the C-type lectin and Mytilin B and the up-regulation of Myticin A. In turn, these results evidence that pCO₂-driven OA scenarios might triggers specific immune-related genes at early stages of infection, promoting the transcription of antimicrobial peptides and patterns recognition receptors. This study provides new evidence of how the immune response of bivalves is modulated by higher CO2 conditions in the ocean, as well one factor for the resilience of marine population upon global change scenarios.

Comparison between absorption and biological activity on the efficiency of the biotrickling filtration of gaseous streams containing ammonia

Polluted air streams can be purified using biological treatments such as biotrickling filtration, which is one of the most widely accepted techniques successfully tuned to treat a wide variety of exhausted gaseous streams coming from a series of industrial sectors such as food processing, flavor manufacturers, rendering, and composting. Since the degradation of a pollutant occurs at standard pressure and temperature, biotrickling filtration, whether compared with other more energy-demanding chemical-physical processes of abatement (such as scrubbing, catalytic oxidation, regenerative adsorption, incineration, advanced oxidation processes, etc.), represents a very high energy-efficient technology. Moreover, as an additional advantage, biodegradation offers the possibility of a complete mineralization of the polluting agents. In this work, biotrickling filtration has been considered in order to explore its efficiency with respect to the abatement of ammonia (which is a highly water-soluble compound). Moreover, a complete mathematical model has been developed in order to describe the dynamics of both absorption and biological activities which are the two dominant phenomena occurring into these systems. The results obtained in this work have shown that the absorption phenomenon is very important in order to define the global removal efficiency of ammonia from the gaseous stream (particularly, 44% of the ammonia is abated by water absorption). Moreover, it has been demonstrated (through the comparison between experimental results and theoretical simulations) that the action of bacteria, which enhance the rate of ammonia transfer to the liquid phase, can be modeled through a simple Michaelis-Menten relationship.

Genome-wide identification, characterization and expression analyses of TLRs in Yesso scallop (Patinopecten yessoensis) provide insight into the disparity of responses to acidifying exposure in bivalves

Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing specific pathogen-associated molecular patterns, including lipoproteins, lipopeptides, lipopolysaccharide, flagellin, dsRNA, ssRNA and CpG DNA motifs. Although significant effects of TLRs on immunity have been reported in most vertebrates and some invertebrates, the complete TLR superfamily has not been systematically characterized in scallops. In this study, 18 TLR genes were identified from Yesso scallop (Patinopecten yessoensis) using whole-genome scanning. Phylogenetic and protein structural analyses were performed to determine the identities and evolutionary relationships of the 18 genes. Extensive expansion of TLR genes from the Yesso scallop genome indicated gene duplication events. In addition, expression profiling of PyTLRs was performed at different acidifying exposure levels (pH = 6.50, 7.50) with different challenge durations (3, 6, 12 and 24 h) via in silico analysis using transcriptome and genome databases. Our results confirmed the inducible expression patterns of PyTLRs under acidifying exposure, and the responses to immune stress may have arisen through adaptive recruitment of tandem duplications of TLR genes. Collectively, this study provides novel insight into PyTLRs as well as the specific role and response of TLR signaling pathways in host immune responses against acidifying exposure in bivalves.

Mass spectrometry data from a quantitative analysis of protein expression in gills of immuno-challenged blue mussels (Mytilus edulis)

Here, we provide the dataset associated with our research article on the potential effects of ocean acidification on antimicrobial peptide (AMP) activity in the gills of Mytilus edulis, “Impact of ocean acidification on antimicrobial activity in gills of the blue mussel (Mytilus edulis)” [1]. Blue mussels were stimulated with lipopolysaccharides and samples were collected at different time points post injection. Protein extracts were prepared from the gills, digested using trypsin and a full in-depth proteome investigation was performed using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Protein identification and quantification was performed using the MaxQuant 1.5.1.2 software, “MaxQuant enables high peptide identification rates, individualized p.p.b.-range mass accuracies and proteome-wide protein quantification” [2].