With increasing oil exploration in Arctic regions, the risk of an accidental oil spill into the environment is inevitably elevated. As a result, concerns have been raised over the potential impact of oil exposure on Arctic organisms. This study assessed the effects of an acute oil exposure (mimicking an accidental spill) on the immune function and oxidative stress status of the Arctic scallop Chlamys islandica. Scallops were exposed to the water accommodated fraction of crude oil over 21 d (maximum SigmaPAH 163 microg l(-1)) and immune endpoints and oxidative stress parameters were measured. Mortalities were recorded during the exposure and reductions in immunocompetence were observed, with significant impairment of phagocytosis and cell membrane stability. Scallops were also subjected to oxidative stress, with a significant reduction in glutathione levels and induction of lipid peroxidation. After the acute oil exposure had subsided, no recovery of immune function was observed indicating potential for prolonged sublethal effects.
"Oil spills seriously harm the marine environment and its inhabitants. The grave consequences of oil pollution for living organisms are their mortality, impaired larval development, changes in oxygen consumption, nutrition, growth, as well as various molecular, cellular, biochemical and physiological modifications resulting in a change in overall enzymatic activity, transformations in the macromolecule and membrane structures and properties and, finally, ecophysiological consequences—a general decline in the population vitality leading to changes in the ecosystem at large (Capuzzo, 1987; McDowell et al., 1999; Lavado et al., 2006; Lima et al., 2007; Baussant et al., 2009; Hannam et al., 2010; Baussant et al., 2011). The oil pollution effect on the organism as well as the impact of most organic and inorganic contaminants depends on many accompanying physical and biological factors such as salinity and oxygen conditions, temperature changes, currents, presence of the ice and snow cover, season, reproduction cycle and others (Wilson et al., 1992; Eertman et al., 1993; Thomas et al., 1999; Schiedek et al., 2006; Broeg and Lehtonen, 2006; Monserrat et al., 2007; Hamer et al., 2008; Bussell et al., 2008). "
[Show abstract][Hide abstract] ABSTRACT: A study on the effect oil pollution under normal and reduced salinity had on blue mussels Mytilus edulis L. from the White Sea in an aquarium-based experiment and in the natural habitat revealed a change in gill total lipids as a compensatory response. The cholesterol concentration and the cholesterol/phospholipids ratio in gills were found to reflect the impact of the environmental factors (oil pollution and desalination), and evidence adaptive changes in the cell membrane structure. An elevated content of storage lipids (chiefly triacylglycerols) in the mussels in the aquarium experiment indicates, first of all, the uptake and accumulation of oil products in gill cells under both normal and reduced seawater salinity, while high triacylglycerols level in gill littoral mussels from 'control' biotope in the Gulf of Kandalaksha is primarily associated with the mussel׳s pre-spawning period.
"As concern scallops, recent experiments conducted in Patinopecten yessoensis and C. farreri [39e 42] attest an increasing interest in immunity of Pectinidae. However , very scarce information is available on P. maximus immunerelated genes and, to date, the limited knowledge of the king scallop immune defense derives mostly from immunohistochemical and biochemical assays   . "
[Show abstract][Hide abstract] ABSTRACT: Pecten maximus, the king scallop, is a bivalve species with important commercial value for both fisheries and aquaculture, traditionally consumed in several European countries. Major problems in larval rearing, however, still limit hatchery-based seed production. High mortalities during early larval stages, likely related to bacterial pathogens, represent the most relevant bottleneck. To address this issue, understanding host defense mechanisms against microbes is extremely important. In this study next-generation RNA-sequencing was carried on scallop hemocytes. To enrich for immune-related transcripts, cDNA libraries from hemocytes challenged in vivo with inactivated-Vibrio anguillarum and in vitro with pathogen-associated molecular patterns, as well as unchallenged controls, were sequenced yielding 216,444,674 sequence reads. De novo assembly of the scallop hemocyte transcriptome consisted of 73,732 contigs (31% annotated). A total of 934 contigs encoded proteins with a known immune function, grouped into several functional categories. Particular attention was reserved to Toll-like receptors (TLRs), a family of pattern recognition receptors (PRRs) involved in non-self recognition. Through mining the scallop hemocyte transcriptome, at least four TLRs could be identified. The organization of canonical TLR domains demonstrated that single cysteine cluster and multiple cysteine cluster TLRs co-exist in this species. In addition, preliminary data concerning their mRNA level following bacterial challenge suggested that different members of this family could exhibit opposite responses to pathogenic stimuli. Finally, a global analysis of differential expression comparing gene-expression levels in in vitro and in vivo stimulated hemocytes against controls provided evidence on a large set of transcripts involved in the great scallop immune response.
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