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Bassem Allam - One of the best experts on this subject based on the ideXlab platform.

  • identification of variants associated with hard clam mercenaria mercenaria resistance to quahog parasite unknown disease
    Genomics, 2020
    Co-Authors: Sarah Farhat, Ximing Guo, Roxanna M Smolowitz, Emmanuelle Pales Espinosa, Arnaud Tanguy, Isabelle Boutet, Diane Murphy, Gregg Rivara, Bassem Allam
    Abstract:

    Abstract Severe losses in aquacultured and wild hard clam (mercenaria mercenaria) stocks have been previously reported in the northeastern United States due to a protistan parasite called QPX (Quahog Parasite Unknown). Previous work demonstrated that clam resistance to QPX is under genetic control. This study identifies single nucleotide polymorphism (SNP) associated with clam survivorship from two geographically segregated populations, both deployed in an enzootic site. The analysis contrasted samples collected before and after undergoing QPX-related mortalities and relied on a robust draft clam genome assembly. ~200 genes displayed significant variant enrichment at each sampling point in both populations, including 18 genes shared between both populations. Markers from both populations were identified in genes related to apoptosis pathways, protein-protein interaction, receptors, and signaling. This research begins to identify genetic markers associated with clam resistance to QPX disease, leading the way for the development of resistant clam stocks through marker-assisted selection.

  • experimental acidification increases susceptibility of mercenaria mercenaria to infection by vibrio species
    Marine Environmental Research, 2020
    Co-Authors: Caroline Schwaner, Christopher J. Gobler, Emmanuelle Pales Espinosa, Andrew W Griffith, Michelle Barbosa, Peter Connors, Taejin Park, Darren De Silva, Bassem Allam
    Abstract:

    Abstract Ocean acidification alters seawater carbonate chemistry, which can have detrimental impacts for calcifying organisms such as bivalves. This study investigated the physiological cost of resilience to acidification in mercenaria mercenaria, with a focus on overall immune performance following exposure to Vibrio spp. Larval and juvenile clams reared in seawater with high pCO2 (~1200 ppm) displayed an enhanced susceptibility to bacterial pathogens. Higher susceptibility to infection in clams grown under acidified conditions was derived from a lower immunity to infection more so than an increase in growth of bacteria under high pCO2. A reciprocal transplant of juvenile clams demonstrated the highest mortality amongst animals transplanted from low pCO2/high pH to high pCO2/low pH conditions and then exposed to bacterial pathogens. Collectively, these results suggest that increased pCO2 will result in immunocompromised larvae and juveniles, which could have complex and pernicious effects on hard clam populations.

  • Allam B: Effects of temperature on hard clam (mercenaria mercenaria) immunity and QPX (Quahog Parasite Unknown) disease development: II. Defense parameters
    2020
    Co-Authors: Mickael Perrigault, Laura Gambino, Emmanuelle Soren F Dahl, Pales Espinosa, Bassem Allam
    Abstract:

    a b s t r a c t Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27°C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13°C compared to 21 and 27°C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27°C whereas different responses were observed at 21°C and 13°C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13°C and 21°C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development

  • effect of heat shock treatments on qpx disease and stress response in the hard clam mercenaria mercenaria
    Journal of Invertebrate Pathology, 2016
    Co-Authors: Kailai Wang, Emmanuelle Pales Espinosa, Bassem Allam
    Abstract:

    Abstract The hard clam, mercenaria mercenaria, is one of the most valuable commercial mollusk species along the eastern coast of the United States. Throughout the past 2 decades, the hard clam industry in the Northeast was significantly impacted by disease outbreaks caused by a lethal protistan parasite known as Quahog Parasite Unknown (QPX). QPX is an opportunistic pathogen and the infection has been shown to be a cold water disease, where warmer conditions (above 21 °C) lead to disease reduction and clam healing. In vitro studies also showed a sharp reduction in parasite growth and survivorship at temperatures exceeding 27 °C. In this study, we evaluated the effect of short-term exposures to high temperatures on QPX disease dynamic and clam recovery. Infected clams were collected from an enzootic site and subsequently submitted to one of ten “heat shock” treatments involving a gradient of temperatures and exposure times. QPX prevalence was compared before and 10 weeks after heat shock to assess the effect of each treatment on disease progress. Expression of several stress-related genes was measured 1 and 7 days after heat shock using qPCR to evaluate the effect of each treatment on clam physiology. Anti-QPX activity in clam plasma was also measured in an attempt to link changes in defense factors to thermal stress and disease progress. Our results suggest that brief exposures to moderate high temperatures promote the greatest remission while imposing the mildest stress to clams. These results are discussed with the aim of providing the industry with possible strategies to mitigate QPX disease.

  • differential immune response in the hard clam mercenaria mercenaria against bacteria and the protistan pathogen qpx quahog parasite unknown
    Fish & Shellfish Immunology, 2012
    Co-Authors: Mickael Perrigault, Bassem Allam
    Abstract:

    The immune response of the hard clam (quahog) mercenaria mercenaria following challenge with live bacteria (Vibrio alginolyticus) and the protist QPX (Quahog Parasite Unknown) was investigated. The study also compared immune responses following QPX challenge in two different hard clam broodstocks exhibiting different degrees of susceptibility toward this parasite. Different immune and stress-related cellular and humoral factors were assessed including general hemocyte parameters (total and differential hemocyte counts, percentage of dead cells, reactive oxygen production, phagocytosis), parameters geared toward QPX (anti-QPX activity in plasma and hemocyte resistance to the cytotoxicity of QPX extracellular products). Two genes (ferritin and metallothionein) previously shown to be modulated following QPX exposure were molecularly characterized by rapid amplification of cDNA ends (RACE) and their transcription levels were determined in resistant and susceptible clams in response to QPX and bacterial challenge. Results indicated that both V. alginolyticus and QPX challenge triggered significant immune responses in clams with similar trends for most measured parameters. However, specific responses were observed for anti-QPX activity in plasma and hemocyte resistance to QPX products as well as ferritin and metallothionein expression according to each inoculum. Similarly, different response patterns were detected following QPX challenge in susceptible and resistant clam stocks. Resistant clams were able to elicit effective response against the parasite leading to the elimination of QPX and the restoration of constitutive immune status whereas QPX-susceptible clams triggered a strong immune modulation characterized by an acute phase response and associated acute phase protein but appeared to be less active in eliminating the parasite. These results suggest that different signaling pathways are triggered during V. alginolyticus and QPX challenge. Moreover, differences in the immune response toward QPX might be linked to the susceptibility or resistance of different clam stocks to the infection by this parasite.

Mickael Perrigault - One of the best experts on this subject based on the ideXlab platform.

  • Allam B: Effects of temperature on hard clam (mercenaria mercenaria) immunity and QPX (Quahog Parasite Unknown) disease development: II. Defense parameters
    2020
    Co-Authors: Mickael Perrigault, Laura Gambino, Emmanuelle Soren F Dahl, Pales Espinosa, Bassem Allam
    Abstract:

    a b s t r a c t Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27°C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13°C compared to 21 and 27°C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27°C whereas different responses were observed at 21°C and 13°C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13°C and 21°C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development

  • differential immune response in the hard clam mercenaria mercenaria against bacteria and the protistan pathogen qpx quahog parasite unknown
    Fish & Shellfish Immunology, 2012
    Co-Authors: Mickael Perrigault, Bassem Allam
    Abstract:

    The immune response of the hard clam (quahog) mercenaria mercenaria following challenge with live bacteria (Vibrio alginolyticus) and the protist QPX (Quahog Parasite Unknown) was investigated. The study also compared immune responses following QPX challenge in two different hard clam broodstocks exhibiting different degrees of susceptibility toward this parasite. Different immune and stress-related cellular and humoral factors were assessed including general hemocyte parameters (total and differential hemocyte counts, percentage of dead cells, reactive oxygen production, phagocytosis), parameters geared toward QPX (anti-QPX activity in plasma and hemocyte resistance to the cytotoxicity of QPX extracellular products). Two genes (ferritin and metallothionein) previously shown to be modulated following QPX exposure were molecularly characterized by rapid amplification of cDNA ends (RACE) and their transcription levels were determined in resistant and susceptible clams in response to QPX and bacterial challenge. Results indicated that both V. alginolyticus and QPX challenge triggered significant immune responses in clams with similar trends for most measured parameters. However, specific responses were observed for anti-QPX activity in plasma and hemocyte resistance to QPX products as well as ferritin and metallothionein expression according to each inoculum. Similarly, different response patterns were detected following QPX challenge in susceptible and resistant clam stocks. Resistant clams were able to elicit effective response against the parasite leading to the elimination of QPX and the restoration of constitutive immune status whereas QPX-susceptible clams triggered a strong immune modulation characterized by an acute phase response and associated acute phase protein but appeared to be less active in eliminating the parasite. These results suggest that different signaling pathways are triggered during V. alginolyticus and QPX challenge. Moreover, differences in the immune response toward QPX might be linked to the susceptibility or resistance of different clam stocks to the infection by this parasite.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development i dynamics of qpx disease
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Soren F. Dahl, Qianqian Liu, Jackie L Collier, Mickael Perrigault, Debra Barnes, Bassem Allam
    Abstract:

    Abstract Quahog Parasite Unknown (QPX) causes disease and mortality in hard clams, mercenaria mercenaria . Seasonality of QPX disease prevalence in the field and changes in QPX growth and survival in vitro suggest a role of temperature in the hard clam-QPX interaction and disease development. This study specifically examined the effect of temperature on QPX disease development and dynamics. Naturally and experimentally infected clams were separately maintained in the laboratory at 13 °C, 21 °C, or 27 °C for 4 months. Following this initial treatment, temperature was adjusted to 21 °C for 5 additional months to simulate seasonal changes of temperature in the field and to investigate the effect of temperature variations on QPX disease dynamics. Mortality was continuously monitored during the experiment and clams were sampled at 2, 4 and 9 months for the assessment of QPX disease prevalence and intensity using our standard histological and quantitative PCR techniques. Results demonstrated significantly higher QPX disease prevalence and intensity, as well as higher mortality, in naturally-infected clams maintained at 13 °C as compared to those held at 21 °C or 27 °C. Similarly, disease development was significantly higher in experimentally infected clams maintained at the colder temperature (70% prevalence after 4 months) as compared to those maintained under warmer conditions ( jointly submitted paper ) and highlighted the impact of temperature on clam activity and QPX disease dynamics. These findings should be taken into account for the timing of activities involving the monitoring, movement (e.g. relays, transplants) or grow out (e.g. commercial culture, municipal enhancement) of hard clams in enzootic areas.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development ii defense parameters
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Mickael Perrigault, Soren F. Dahl, Emmanuelle Pales Espinosa, Laura Gambino, Bassem Allam
    Abstract:

    Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27 C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13 C compared to 21 and 27 C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27 C whereas different responses were observed at 21 C and 13 C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13 C and 21 C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development i dynamics of qpx disease
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Soren F. Dahl, Qianqian Liu, Jackie L Collier, Mickael Perrigault, Debra Barnes, Bassem Allam
    Abstract:

    Quahog Parasite Unknown (QPX) causes disease and mortality in hard clams, mercenaria mercenaria. Seasonality of QPX disease prevalence in the field and changes in QPX growth and survival in vitro suggest a role of temperature in the hard clam-QPX interaction and disease development. This study specifically examined the effect of temperature on QPX disease development and dynamics. Naturally and experimentally infected clams were separately maintained in the laboratory at 13°C, 21°C, or 27°C for 4 months. Following this initial treatment, temperature was adjusted to 21°C for 5 additional months to simulate seasonal changes of temperature in the field and to investigate the effect of temperature variations on QPX disease dynamics. Mortality was continuously monitored during the experiment and clams were sampled at 2, 4 and 9 months for the assessment of QPX disease prevalence and intensity using our standard histological and quantitative PCR techniques. Results demonstrated significantly higher QPX disease prevalence and intensity, as well as higher mortality, in naturally-infected clams maintained at 13°C as compared to those held at 21°C or 27°C. Similarly, disease development was significantly higher in experimentally infected clams maintained at the colder temperature (70% prevalence after 4 months) as compared to those maintained under warmer conditions (<10%). Additionally, our results demonstrated an improvement in the condition of clams initially maintained at 13°C for 4 months after transfer to 21°C for 5 additional months, with a significant reduction of QPX prevalence (down to 19%). Interestingly, disease development or healing in clams maintained at different temperatures exhibited a strong relationship with clam defense status (jointly submitted paper) and highlighted the impact of temperature on clam activity and QPX disease dynamics. These findings should be taken into account for the timing of activities involving the monitoring, movement (e.g. relays, transplants) or grow out (e.g. commercial culture, municipal enhancement) of hard clams in enzootic areas.

Inna M Sokolova - One of the best experts on this subject based on the ideXlab platform.

  • interactive effects of copper exposure and environmental hypercapnia on immune functions of marine bivalves crassostrea virginica and mercenaria mercenaria
    Fish & Shellfish Immunology, 2016
    Co-Authors: Anna V Ivanina, Chelsea Hawkins, Inna M Sokolova
    Abstract:

    Abstract Estuarine organisms such as bivalves are commonly exposed to trace metals such as copper (Cu) and hypercapnia (elevated CO 2 levels) in their habitats, which may affect their physiology and immune function. This study investigated the combined effects of elevated CO 2 levels (∼800–2000 μatm P CO2 , such as predicted by the near-future scenarios of global climate change) and Cu (50 μg l −1 ) on immune functions of the sediment dwelling hard clams mercenaria mercenaria and an epifaunal bivalve, the eastern oyster Crassostrea virginica. Clams and oysters were exposed for 4 weeks to different CO 2 and Cu levels, and tissue Cu burdens and immune parameters were assessed to test the hypothesis that hypercapnia will enhance Cu uptake due to the higher bioavailability of free Cu 2+ and increase the immunomodulatory effects of Cu. Exposure to Cu stimulated key immune parameters of clams and oysters leading to increased number of circulating hemocytes, higher phagocytosis and adhesion ability of hemocytes, as well as enhanced antiparasitic and antibacterial properties of the hemolymph reflected in higher activities of lysozyme and inhibitors of cysteine proteases. Lysozyme activation by Cu exposure was most prominent in normocapnia (∼400 μatm P CO2 ) and an increase in the levels of the protease inhibitors was strongest in hypercapnia (∼800–2000 μatm P CO2 ), but other immunostimulatory effects of Cu were evident in all P CO2 exposures. Metabolic activity of hemocytes of clams and oysters (measured as routine and mitochondrial oxygen consumption rates) was suppressed by Cu exposure likely reflecting lower rates of ATP synthesis and/or turnover. However, this metabolic suppression had no negative effects of the studied immune functions of hemocytes such as phagocytosis or adhesion capacity. Hypercapnia (∼800–2000 μatm P CO2 ) slightly but significantly enhanced accumulation of Cu in hemocytes, consistent with higher Cu 2+ bioavailability in CO 2 -acidified water, but had little effect on cellular and humoral immune traits of clams and oysters. These findings indicate that low levels of Cu contamination may enhance immunity of estuarine bivalves while moderate hypercapnia (such as predicted by the near future scenarios of the global climate change) does not strongly affect their immune parameters.

  • immunomodulation by the interactive effects of cadmium and hypercapnia in marine bivalves crassostrea virginica and mercenaria mercenaria
    Fish & Shellfish Immunology, 2014
    Co-Authors: Anna V Ivanina, Chelsea Hawkins, Inna M Sokolova
    Abstract:

    Estuarine organisms are exposed to multiple stressors including large fluctuations in partial pressure of carbon dioxide (P2CO) and concentrations of trace metals such as cadmium (Cd) that can affect their survival and fitness. Ocean acidification due to the increasing atmospheric (P2CO) leads to a decrease in pH and shifts in the carbonate chemistry of seawater which can change bioavailability and toxicity of metals. We studied the interactive effects of (P2CO) and Cd exposure on metal levels, metabolism and immune-related functions in hemocytes of two ecologically and economically important bivalve species, mercenaria mercenaria (hard shell clam) and Crassostrea virginica (Eastern oyster). Clams and oysters were exposed to combinations of three (P2CO) levels (∼400, 800 and 2000 μatm (P2CO), corresponding to the present day conditions and the projections for the years 2100 and 2250, respectively) and two Cd concentrations (0 and 50 μg l(-1)) in seawater. Following four weeks of exposure to Cd, hemolymph of both species contained similar Cd levels (50-70 μg l(-1)), whereas hemocytes accumulated intracellular Cd burdens up to 15-42 mg l(-1), regardless of the exposure P2CO. Clam hemocytes had considerably lower Cd burdens than those of oysters (0.7-1 ng 10(-6) cells vs. 4-6 ng 10(-6) cells, respectively). Cd exposure suppressed hemocyte metabolism and increased the rates of mitochondrial proton leak in normocapnia indicating partial mitochondrial uncoupling. This Cd-induced mitochondrial uncoupling was alleviated in hypercapnia. Cd exposure suppressed immune-related functions in hemocytes of clams and oysters, and these effects were exacerbated at elevated (P2CO). Thus, elevated (P2CO) combined with Cd exposure resulted in decrease in phagocytic activity and adhesion capacity as well as lower expression of mRNA for lectin and heat shock protein (HSP70) in clam and oyster hemocytes. In oysters, combined exposure to elevated (P2CO) and Cd also led to reduced activity of lysozyme in hemocytes and hemolymph. Overall, our study shows that moderately elevated (P2CO) (∼800-2000 μatm P2CO) potentiates the negative effects of Cd on immunity and thus may sensitize clams and oysters to pathogens and diseases during seasonal hypercapnia and/or ocean acidification in polluted estuaries.

  • interactive effects of ph and metals on mitochondrial functions of intertidal bivalves crassostrea virginica and mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Inna M Sokolova
    Abstract:

    Abstract Intertidal bivalves experience broad fluctuations of environmental temperature, pH and oxygen content which could change their intracellular pH. They are also exposed to trace metals such as cadmium (Cd) and copper (Cu) that accumulate in their tissues and may negatively affect mitochondrial functions and bioenergetics. We determined the interactive effects of pH and trace metals (25 μM Cd or Cu) on mitochondrial functions (including respiration and membrane potentials in both ADP-stimulated (state 3) and resting (state 4) states) of two common marine bivalves, the hard clams ( mercenaria mercenaria ) and eastern oysters ( Crassostrea virginica ). In the absence of the trace metals, mitochondrial functions of C. virginica and M. mercenaria were insensitive to pH in a broad physiologically relevant range (6.6–7.8). Mitochondrial respiration was generally suppressed by 25 μM Cd or Cu (with the stronger effects observed for ADP-stimulated compared to the resting respiration) while the mitochondrial membrane potential was unaffected. pH modulated the effects of Cu and Cd on mitochondrial respiration of the bivalves. In oysters, Cu suppressed ADP-stimulated mitochondrial respiration at high and low pH values (6.6 and 7.8, respectively), but had no effect in the intermediate pH range (7.0–7.4). In clams, the negative effect of Cu on ADP-stimulated respiration was only observed at extremely high pH (7.8). A decrease in pH was also protective against Cd in mitochondria of clams and oysters. In clams, 25 μM Cd suppressed ADP-stimulated respiration at all pH; however, at low pH (6.6–7.0) this suppression was paralleled by a decrease in the rates of proton leak thereby effectively restoring mitochondrial coupling. In oysters, the inhibitory effects of Cd on ADP-stimulated respiration were fully abolished at low pH (6.6–7.0). This indicates that moderate acidosis (such as occurs during exposure to air, extreme salinities or elevated CO 2 levels in the intertidal zone) may have a beneficial side-effect of protecting mitochondria of clams and oysters against the toxic effects of trace metals in polluted estuaries.

  • short term acute hypercapnia affects cellular responses to trace metals in the hard clams mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Amy H Ringwood, Elia Beniash, Markus Etzkorn, Tiffany B Meyers, Inna M Sokolova
    Abstract:

    Abstract Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( P CO 2 ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high P CO 2 (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between P CO 2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (mercenaria mercenaria) to different levels of P CO 2 (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated P CO 2 resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated P CO 2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated P CO 2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd2+ concentration remained the same, while intracellular levels of free Zn2+ increased suggesting that Cd2+ substitutes bound Zn2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn2+ but led to a profound increase in the intracellular levels of labile Cu2+ and Fe2+. An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa P CO 2 ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and P CO 2 in clams and indicate that variations in environmental P CO 2 may modulate the biological effects of trace metals in marine organisms.

  • short term acute hypercapnia affects cellular responses to trace metals in the hard clams mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Amy H Ringwood, Elia Beniash, Markus Etzkorn, Tiffany B Meyers, Inna M Sokolova
    Abstract:

    Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and [Formula: see text] in clams and indicate that variations in environmental [Formula: see text] may modulate the biological effects of trace metals in marine organisms.

Soren F. Dahl - One of the best experts on this subject based on the ideXlab platform.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development ii defense parameters
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Mickael Perrigault, Soren F. Dahl, Emmanuelle Pales Espinosa, Laura Gambino, Bassem Allam
    Abstract:

    Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27 C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13 C compared to 21 and 27 C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27 C whereas different responses were observed at 21 C and 13 C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13 C and 21 C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development i dynamics of qpx disease
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Soren F. Dahl, Qianqian Liu, Jackie L Collier, Mickael Perrigault, Debra Barnes, Bassem Allam
    Abstract:

    Abstract Quahog Parasite Unknown (QPX) causes disease and mortality in hard clams, mercenaria mercenaria . Seasonality of QPX disease prevalence in the field and changes in QPX growth and survival in vitro suggest a role of temperature in the hard clam-QPX interaction and disease development. This study specifically examined the effect of temperature on QPX disease development and dynamics. Naturally and experimentally infected clams were separately maintained in the laboratory at 13 °C, 21 °C, or 27 °C for 4 months. Following this initial treatment, temperature was adjusted to 21 °C for 5 additional months to simulate seasonal changes of temperature in the field and to investigate the effect of temperature variations on QPX disease dynamics. Mortality was continuously monitored during the experiment and clams were sampled at 2, 4 and 9 months for the assessment of QPX disease prevalence and intensity using our standard histological and quantitative PCR techniques. Results demonstrated significantly higher QPX disease prevalence and intensity, as well as higher mortality, in naturally-infected clams maintained at 13 °C as compared to those held at 21 °C or 27 °C. Similarly, disease development was significantly higher in experimentally infected clams maintained at the colder temperature (70% prevalence after 4 months) as compared to those maintained under warmer conditions ( jointly submitted paper ) and highlighted the impact of temperature on clam activity and QPX disease dynamics. These findings should be taken into account for the timing of activities involving the monitoring, movement (e.g. relays, transplants) or grow out (e.g. commercial culture, municipal enhancement) of hard clams in enzootic areas.

  • effects of temperature on hard clam mercenaria mercenaria immunity and qpx quahog parasite unknown disease development i dynamics of qpx disease
    Journal of Invertebrate Pathology, 2011
    Co-Authors: Soren F. Dahl, Qianqian Liu, Jackie L Collier, Mickael Perrigault, Debra Barnes, Bassem Allam
    Abstract:

    Quahog Parasite Unknown (QPX) causes disease and mortality in hard clams, mercenaria mercenaria. Seasonality of QPX disease prevalence in the field and changes in QPX growth and survival in vitro suggest a role of temperature in the hard clam-QPX interaction and disease development. This study specifically examined the effect of temperature on QPX disease development and dynamics. Naturally and experimentally infected clams were separately maintained in the laboratory at 13°C, 21°C, or 27°C for 4 months. Following this initial treatment, temperature was adjusted to 21°C for 5 additional months to simulate seasonal changes of temperature in the field and to investigate the effect of temperature variations on QPX disease dynamics. Mortality was continuously monitored during the experiment and clams were sampled at 2, 4 and 9 months for the assessment of QPX disease prevalence and intensity using our standard histological and quantitative PCR techniques. Results demonstrated significantly higher QPX disease prevalence and intensity, as well as higher mortality, in naturally-infected clams maintained at 13°C as compared to those held at 21°C or 27°C. Similarly, disease development was significantly higher in experimentally infected clams maintained at the colder temperature (70% prevalence after 4 months) as compared to those maintained under warmer conditions (<10%). Additionally, our results demonstrated an improvement in the condition of clams initially maintained at 13°C for 4 months after transfer to 21°C for 5 additional months, with a significant reduction of QPX prevalence (down to 19%). Interestingly, disease development or healing in clams maintained at different temperatures exhibited a strong relationship with clam defense status (jointly submitted paper) and highlighted the impact of temperature on clam activity and QPX disease dynamics. These findings should be taken into account for the timing of activities involving the monitoring, movement (e.g. relays, transplants) or grow out (e.g. commercial culture, municipal enhancement) of hard clams in enzootic areas.

  • Field Performance and QPX Disease Progress in Cultured and Wild-Type Strains of mercenaria mercenaria in New York Waters
    Journal of Shellfish Research, 2010
    Co-Authors: Soren F. Dahl, Joshua Thiel, Bassem Allam
    Abstract:

    ABSTRACT A field experiment was conducted to compare the performance of different hard clam (mercenaria mercenaria) strains in local clamming waters of New York state. Experimental clams included a mercenaria mercenaria notata seed obtained from a Florida broodstock, and 2 New York seed strains obtained from local hatcheries, including a cultured M. mercenaria notata strain and a first-generation “wild-type” strain. Quahog parasite unknown (QPX) was acquired by the Florida clams in less than 2 mo of a July deployment of grow-out cages. Prior field studies comparing susceptibility of northern and southern hard clam strains observed QPX acquisition after clams had overwintered in the field, raising the question that higher susceptibility observed in southern seed clams could be a result of poor adaptation to winter water temperatures. Our results show that the southern strain acquired QPX after the clams had only been exposed to the warmest period of water temperatures for this field site (22.3°C on average...

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  • interactive effects of copper exposure and environmental hypercapnia on immune functions of marine bivalves crassostrea virginica and mercenaria mercenaria
    Fish & Shellfish Immunology, 2016
    Co-Authors: Anna V Ivanina, Chelsea Hawkins, Inna M Sokolova
    Abstract:

    Abstract Estuarine organisms such as bivalves are commonly exposed to trace metals such as copper (Cu) and hypercapnia (elevated CO 2 levels) in their habitats, which may affect their physiology and immune function. This study investigated the combined effects of elevated CO 2 levels (∼800–2000 μatm P CO2 , such as predicted by the near-future scenarios of global climate change) and Cu (50 μg l −1 ) on immune functions of the sediment dwelling hard clams mercenaria mercenaria and an epifaunal bivalve, the eastern oyster Crassostrea virginica. Clams and oysters were exposed for 4 weeks to different CO 2 and Cu levels, and tissue Cu burdens and immune parameters were assessed to test the hypothesis that hypercapnia will enhance Cu uptake due to the higher bioavailability of free Cu 2+ and increase the immunomodulatory effects of Cu. Exposure to Cu stimulated key immune parameters of clams and oysters leading to increased number of circulating hemocytes, higher phagocytosis and adhesion ability of hemocytes, as well as enhanced antiparasitic and antibacterial properties of the hemolymph reflected in higher activities of lysozyme and inhibitors of cysteine proteases. Lysozyme activation by Cu exposure was most prominent in normocapnia (∼400 μatm P CO2 ) and an increase in the levels of the protease inhibitors was strongest in hypercapnia (∼800–2000 μatm P CO2 ), but other immunostimulatory effects of Cu were evident in all P CO2 exposures. Metabolic activity of hemocytes of clams and oysters (measured as routine and mitochondrial oxygen consumption rates) was suppressed by Cu exposure likely reflecting lower rates of ATP synthesis and/or turnover. However, this metabolic suppression had no negative effects of the studied immune functions of hemocytes such as phagocytosis or adhesion capacity. Hypercapnia (∼800–2000 μatm P CO2 ) slightly but significantly enhanced accumulation of Cu in hemocytes, consistent with higher Cu 2+ bioavailability in CO 2 -acidified water, but had little effect on cellular and humoral immune traits of clams and oysters. These findings indicate that low levels of Cu contamination may enhance immunity of estuarine bivalves while moderate hypercapnia (such as predicted by the near future scenarios of the global climate change) does not strongly affect their immune parameters.

  • immunomodulation by the interactive effects of cadmium and hypercapnia in marine bivalves crassostrea virginica and mercenaria mercenaria
    Fish & Shellfish Immunology, 2014
    Co-Authors: Anna V Ivanina, Chelsea Hawkins, Inna M Sokolova
    Abstract:

    Estuarine organisms are exposed to multiple stressors including large fluctuations in partial pressure of carbon dioxide (P2CO) and concentrations of trace metals such as cadmium (Cd) that can affect their survival and fitness. Ocean acidification due to the increasing atmospheric (P2CO) leads to a decrease in pH and shifts in the carbonate chemistry of seawater which can change bioavailability and toxicity of metals. We studied the interactive effects of (P2CO) and Cd exposure on metal levels, metabolism and immune-related functions in hemocytes of two ecologically and economically important bivalve species, mercenaria mercenaria (hard shell clam) and Crassostrea virginica (Eastern oyster). Clams and oysters were exposed to combinations of three (P2CO) levels (∼400, 800 and 2000 μatm (P2CO), corresponding to the present day conditions and the projections for the years 2100 and 2250, respectively) and two Cd concentrations (0 and 50 μg l(-1)) in seawater. Following four weeks of exposure to Cd, hemolymph of both species contained similar Cd levels (50-70 μg l(-1)), whereas hemocytes accumulated intracellular Cd burdens up to 15-42 mg l(-1), regardless of the exposure P2CO. Clam hemocytes had considerably lower Cd burdens than those of oysters (0.7-1 ng 10(-6) cells vs. 4-6 ng 10(-6) cells, respectively). Cd exposure suppressed hemocyte metabolism and increased the rates of mitochondrial proton leak in normocapnia indicating partial mitochondrial uncoupling. This Cd-induced mitochondrial uncoupling was alleviated in hypercapnia. Cd exposure suppressed immune-related functions in hemocytes of clams and oysters, and these effects were exacerbated at elevated (P2CO). Thus, elevated (P2CO) combined with Cd exposure resulted in decrease in phagocytic activity and adhesion capacity as well as lower expression of mRNA for lectin and heat shock protein (HSP70) in clam and oyster hemocytes. In oysters, combined exposure to elevated (P2CO) and Cd also led to reduced activity of lysozyme in hemocytes and hemolymph. Overall, our study shows that moderately elevated (P2CO) (∼800-2000 μatm P2CO) potentiates the negative effects of Cd on immunity and thus may sensitize clams and oysters to pathogens and diseases during seasonal hypercapnia and/or ocean acidification in polluted estuaries.

  • interactive effects of ph and metals on mitochondrial functions of intertidal bivalves crassostrea virginica and mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Inna M Sokolova
    Abstract:

    Abstract Intertidal bivalves experience broad fluctuations of environmental temperature, pH and oxygen content which could change their intracellular pH. They are also exposed to trace metals such as cadmium (Cd) and copper (Cu) that accumulate in their tissues and may negatively affect mitochondrial functions and bioenergetics. We determined the interactive effects of pH and trace metals (25 μM Cd or Cu) on mitochondrial functions (including respiration and membrane potentials in both ADP-stimulated (state 3) and resting (state 4) states) of two common marine bivalves, the hard clams ( mercenaria mercenaria ) and eastern oysters ( Crassostrea virginica ). In the absence of the trace metals, mitochondrial functions of C. virginica and M. mercenaria were insensitive to pH in a broad physiologically relevant range (6.6–7.8). Mitochondrial respiration was generally suppressed by 25 μM Cd or Cu (with the stronger effects observed for ADP-stimulated compared to the resting respiration) while the mitochondrial membrane potential was unaffected. pH modulated the effects of Cu and Cd on mitochondrial respiration of the bivalves. In oysters, Cu suppressed ADP-stimulated mitochondrial respiration at high and low pH values (6.6 and 7.8, respectively), but had no effect in the intermediate pH range (7.0–7.4). In clams, the negative effect of Cu on ADP-stimulated respiration was only observed at extremely high pH (7.8). A decrease in pH was also protective against Cd in mitochondria of clams and oysters. In clams, 25 μM Cd suppressed ADP-stimulated respiration at all pH; however, at low pH (6.6–7.0) this suppression was paralleled by a decrease in the rates of proton leak thereby effectively restoring mitochondrial coupling. In oysters, the inhibitory effects of Cd on ADP-stimulated respiration were fully abolished at low pH (6.6–7.0). This indicates that moderate acidosis (such as occurs during exposure to air, extreme salinities or elevated CO 2 levels in the intertidal zone) may have a beneficial side-effect of protecting mitochondria of clams and oysters against the toxic effects of trace metals in polluted estuaries.

  • short term acute hypercapnia affects cellular responses to trace metals in the hard clams mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Amy H Ringwood, Elia Beniash, Markus Etzkorn, Tiffany B Meyers, Inna M Sokolova
    Abstract:

    Abstract Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( P CO 2 ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high P CO 2 (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between P CO 2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (mercenaria mercenaria) to different levels of P CO 2 (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated P CO 2 resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated P CO 2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated P CO 2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd2+ concentration remained the same, while intracellular levels of free Zn2+ increased suggesting that Cd2+ substitutes bound Zn2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn2+ but led to a profound increase in the intracellular levels of labile Cu2+ and Fe2+. An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa P CO 2 ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and P CO 2 in clams and indicate that variations in environmental P CO 2 may modulate the biological effects of trace metals in marine organisms.

  • short term acute hypercapnia affects cellular responses to trace metals in the hard clams mercenaria mercenaria
    Aquatic Toxicology, 2013
    Co-Authors: Anna V Ivanina, Amy H Ringwood, Elia Beniash, Markus Etzkorn, Tiffany B Meyers, Inna M Sokolova
    Abstract:

    Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and [Formula: see text] in clams and indicate that variations in environmental [Formula: see text] may modulate the biological effects of trace metals in marine organisms.