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Bassem Allam - One of the best experts on this subject based on the ideXlab platform.
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alterations of the immune transcriptome in resistant and susceptible hard clams Mercenaria Mercenaria in response to quahog parasite unknown qpx and temperature
Fish & Shellfish Immunology, 2016Co-Authors: Kailai Wang, Emmanuelle Pales Espinosa, Arnaud Tanguy, Bassem AllamAbstract:Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria Mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. Mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. Mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. Mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. Mercenaria oligoarray (15 K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 °C) or clam healing (21 °C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of complement-related recognition molecules with fibrinogen or C1q domains were shown to be specially induced following QPX challenge, and the expression of these molecules was significantly higher in resistant clams as compared to susceptible ones. These highly variable immune proteins may be potent candidate molecular markers for future study of M. Mercenaria resistance against QPX. Beyond the specific case of clam response to QPX, this study also provides insights into the primitive complement-like system in the hard clam.
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Field Performance and QPX Disease Progress in Cultured and Wild-Type Strains of Mercenaria Mercenaria in New York Waters
Journal of Shellfish Research, 2010Co-Authors: Soren F. Dahl, Joshua Thiel, Bassem AllamAbstract: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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Oxidative burst in hard clam (Mercenaria Mercenaria) haemocytes
Fish & shellfish immunology, 2006Co-Authors: Deenie M. Buggé, Hélène Hégaret, Gary H. Wikfors, Bassem AllamAbstract:Haemocytes of bivalve molluscs are known to be responsible for many immunological functions, including recognition, phagocytosis, and killing or elimination of invading microorgansisms, such as potentially infective bacteria and parasites. In many bivalves, killing of microorganisms engulfed by haemocytes is accomplished by a sudden release of reactive oxygen species (ROS) within the haemocytes; this response is referred to as an oxidative burst. Previous studies have failed to detect oxidative burst in haemocytes of the hard clam (northern quahog), Mercenaria Mercenaria. In the present study, we applied a widely used chemical probe for ROS detection in haemocytes, dichlorofluorescin-diacetate (DCFH-DA), to haemocytes from this clam species and used flow cytometry to quantify fluorescence in individual haemocytes. Oxidation of DCFH-DA to the fluorescent product, DCF, within unstimulated haemocytes indicated that ROS were clearly produced in these cells. Two activators of oxidative burst, zymosan and bacterial extracellular products, which have been applied successfully to haemocytes in other species, stimulated large increases in ROS production in hard clam haemocytes. Furthermore, two inhibitors of ROS production, W-13 and diphenylene iodinium (DPI), significantly suppressed ROS production by haemocytes. Nitric oxide synthase inhibitors, NMMA and L-NIO, did not suppress ROS production, indicating that the observed oxidation of DCFH-DA is not mediated by nitric oxide. These results show unequivocally that haemocyte oxidative burst is active in M. Mercenaria and, therefore, is a likely mechanism in host response to pathogens and parasites. 2006 Elsevier Ltd. All rights reserved.
K.w. Bock - One of the best experts on this subject based on the ideXlab platform.
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Profiles of strontium and barium in Mercenaria Mercenaria and Spisula solidissima shells
Geochimica et Cosmochimica Acta, 1996Co-Authors: H.a. Stecher, David E. Krantz, Christopher J. Lord, George W. Luther, K.w. BockAbstract:Abstract Cross sections of two Mercenaria Mercenaria shells, one modern and one Pleistocene, and one modern Spisula solidissima shell were analyzed for trace metals using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These data are coupled with 18 O 16 O ratio profiles, which are used as a temperature proxy to determine the season of growth for a given shell parcel. The shells show Sr and Ba fluctuations in regular annual patterns. Seasonal Sr decreases associated with the winter dormant period in Mercenaria , and with the summer growth decrease in Spisula indicate that kinetic control (growth rate) plays a more important role than temperature in the incorporation of this element. Barium exhibits sharp increases that are likely linked to periods of intense phytoplankton productivity. This application of LA-ICP-MS to the analysis of mollusk shells for documenting ontogenetic trends demonstrates the power of this technique for extracting geochemical information.
Sandra E Shumway - One of the best experts on this subject based on the ideXlab platform.
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suspension feeding by the atlantic slipper limpet crepidula fornicata and the northern quahog Mercenaria Mercenaria in the presence of cultured and wild populations of the harmful brown tide alga aureococcus anophagefferens
Harmful Algae, 2011Co-Authors: Matthew J Harke, Christopher J Gobler, Sandra E ShumwayAbstract:Within estuaries of New York, USA, recurrent harmful brown tides (Aureococcus anophagefferens) have contributed toward the collapse of two major bivalve fisheries (bay scallop, Argopecten irradians and northern quahog or hard clam, Mercenaria Mercenaria), while populations of the Atlantic slipper limpet Crepidula fornicata have persisted in the presence of these blooms. Rates of suspension feeding by C. fornicata and M. Mercenaria in the presence of different strains of A. anophagefferens and wild brown tide blooms were quantified to assess the potential impact of brown tides on slipper limpet and hard clam populations. Slipper limpets were capable of clearing all strains of A. anophagefferens at biomass-specific rates similar to an ideal food source (Isochrysis galbana), whereas clearance rates of M. Mercenaria fed toxic clones of A. anophagefferens were significantly lower than when fed I. galbana or non-toxic clones of A. anophagefferens (p < 0.01). During brown tide blooms (10 4 –10 6 cells mL � 1 ) on the south shore of Long Island during 2008 and 2009, clearance rates of C. fornicata when fed bloom water were an order of magnitude greater than those of M. Mercenaria (p < 0.001). Finally, during mesocosm experiments, C. fornicata reduced bloom densities of A. anophagefferens (10 6 cells mL � 1 ) by an order of magnitude in 3–4 days, whereas densities of A. anophagefferens in mesocosms stocked with equal or greater biomasses of M. Mercenaria were unchanged. These results demonstrate that C. fornicata can actively feed in the presence of A. anophagefferens and suggest that this species could serve as a top-down control of blooms in shallow, poorly flushed estuaries.
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Chapter 8 Physiological ecology of Mercenaria Mercenaria
Developments in Aquaculture and Fisheries Science, 2001Co-Authors: Raymond E. Grizzle, V. Monica Bricelj, Sandra E ShumwayAbstract:Publisher Summary This chapter discusses the physiological ecology of Mercenaria Mercenaria with emphasis on feeding, nutrition, growth, and production. It also includes a review of whole-organism behavior relevant to feeding. A consideration of energy flow through the organism provides the organizing framework. The major terms that deal with energetic are also introduced in the chapter. The various anatomical structures and associated physiological processes are considered in the chapter. The aspects of energy acquisition, which include feeding and various post-ingestion processes, are also reviewed. Energy expenditures such as biodeposition, excretion, and other metabolic “costs” such as respiration are described in the chapter. The vast majority of the research on hard clams is concerned with growth and factors that influence it. The extrinsic (environmental) factors affecting growth are also emphasized. The feeding responses largely explain the patterns of individual growth responses. The chapter also reviews the whole-organism behavior and provides a fluid mechanical perspective on the feeding environment experienced by clams in nature. Feeding occurs close to the bottom, well within the benthic boundary layer, because of the hard clam's infaunal life habit and the relatively short length of its siphons.
Chester B. Zarnoch - One of the best experts on this subject based on the ideXlab platform.
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Geographic origin and culture method influence the overwinter mortality of juvenile hard clams, Mercenaria Mercenaria (L.)
Aquaculture, 2015Co-Authors: Chester B. Zarnoch, John N. Kraeuter, Gef Flimlin, Brian F. Beal, V. Monica Bricelj, David BushekAbstract:Abstract Overwinter mortality of juvenile northern quahogs, Mercenaria Mercenaria, is a major impediment to the aquaculture industry from the mid-Atlantic US through Atlantic Canada. Mortality occurs during prolonged exposures to low temperatures and/or during the winter–spring transition when water temperatures are rising. Recent efforts to overwinter juveniles of M. Mercenaria produced from native Maine (ME, USA) broodstock in eastern ME have found high survival while using a newly adopted methodology (i.e. cages in the water column rather than the standard practice of bottom planting) for overwintering. The current study aimed to determine if the high survivorship was a result of the culture methodology or if the ME genetic stock is better adapted for overwinter survival. Field studies were performed across two consecutive winters in ME, New York (NY) and New Jersey (NJ, USA) to compare survivorship of two size classes of juvenile M. Mercenaria using the new methodology to the standard practice of bottom planting, and to compare the survival and physiological condition of the ME stock vs. the NY and NJ stocks across a latitudinal gradient. The ME stock had greater survival than the NY and NJ stock at all sites and in both study years. Both of the ME size classes exhibited lower mortality ( M. Mercenaria in eastern Maine cannot be applied effectively to more southern locations. However, the results suggest that selective breeding programs may be able to develop aquaculture stocks that are better adapted to overwintering conditions.
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influence of temperature and food availability on the biochemical composition and mortality of juvenile Mercenaria Mercenaria l during the over winter period
Aquaculture, 2008Co-Authors: Chester B. Zarnoch, Martin P SchreibmanAbstract:Abstract Over-winter mortality of juvenile aquacultured northern quahogs (=hard clams), Mercenaria Mercenaria, is a significant problem for the Mid-Atlantic and Northeast aquaculturists. Although protecting seed from predators improves survival, significant mortalities still frequently exceed 50%. The mortality has been attributed to severe winter temperatures, however, this suggestion has yet to be systematically investigated. We hypothesize that extended periods of low water temperatures (
Rochelle D. Seitz - One of the best experts on this subject based on the ideXlab platform.
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Density-dependent predation in different habitats.
2018Co-Authors: Cassandra N. Glaspie, Rochelle D. SeitzAbstract:Mean juvenile Mya arenaria and Mercenaria Mercenaria proportional survival (± 1 SE) in mesocosms when exposed to blue crab predation in a) sand, b) shell hash, c) oyster shell, and d) seagrass. Solid black lines are mean proportional survival for Mya at two initial densities of 4 and 16 per tank, and dashed black lines are mean proportional survival for Mercenaria at two initial densities of 4 and 11 per tank.
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Behavior of blue crab Callinectes sapidus feeding on juvenile Mya arenaria and Mercenaria Mercenaria.
2018Co-Authors: Cassandra N. Glaspie, Rochelle D. SeitzAbstract:Shown are means (± 1 SE) of a) handling time (HT) for crabs feeding on Mya, b) HT for crabs feeding on Mercenaria, c) search time (ST) for crabs feeding on Mya, d) ST for crabs feeding on Mercenaria, e) encounter rate (ER) for crabs feeding on Mya, and f) ER for crabs feeding on Mercenaria. Lines of different colors and patterns represent different habitat types (shell = shell hash; oyster = oyster shell), and means were calculated from n = 3 trials.
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Habitat complexity and benthic predator-prey interactions in Chesapeake Bay
2018Co-Authors: Cassandra N. Glaspie, Rochelle D. SeitzAbstract:In Chesapeake Bay, the soft-shell clam Mya arenaria (thin-shelled, deep-burrowing) exhibits population declines when predators are active, and it persists at low densities. In contrast, the hard clam Mercenaria Mercenaria (thick-shelled, shallow-burrowing) has a stable population and age distribution. We examined the potential for habitat and predators to control densities and distributions of bivalves in a field caging experiment (Mya only) and laboratory mesocosm experiments (both species). In the field, clams exposed to predators experienced 76.3% greater mortality as compared to caged individuals, and blue crabs were likely responsible for most of the mortality of juvenile Mya. In mesocosm experiments, Mya had lower survival in sand and seagrass than in shell hash or oyster shell habitats. However, crabs often missed one or more prey items in seagrass, shell, and oyster shell habitats. Predator search times and encounter rates declined when prey were at low densities, likely due to the added cost of inefficient foraging; however, this effect was more pronounced for Mya than for Mercenaria. Mercenaria had higher survival than Mya in mesocosm experiments, likely because predators feeding on Mercenaria spent less time foraging than those feeding on Mya. Mya may retain a low-density refuge from predation even with the loss of structurally complex habitats, though a loss of habitat refuge may result in clam densities that are not sustainable. A better understanding of density-dependent predator-prey interactions is necessary to prevent loss of food-web integrity and to conserve marine resources.
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ANOVA results for mesocosm study proportional survival of juvenile clams, as well as handling time (HT), search time (ST), and encounter rate (ER) of blue crabs Callinectes sapidus feeding on juvenile clams.
2018Co-Authors: Cassandra N. Glaspie, Rochelle D. SeitzAbstract:Two species (Mya arenaria and Mercenaria Mercenaria) were offered to blue crabs Callinectes sapidus at two densities (low and medium) in tanks with four different habitats (sand, sand with shell hash, sand with oyster shell halves, and sand with live seagrass); all were included in the ANOVA model as fixed factors. Data were Box-Cox transformed (λ = -0.14; survival only) or fourth-root transformed (HT, ST, and ER) prior to analysis. Significant p values (at α = 0.05 for main effects and α = 0.20 for interaction terms) are bolded.