Exploring PAH kinetics in wild vs. transplanted triploid and diploid oysters at a contaminated field site using immunological techniques.

Crassostrea virginica is a well-established bivalve species for biomonitoring persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAH) in aquatic environments. Differing biomonitoring methods employing either wild oysters inhabiting sites of interest or naïve cultured oysters deployed to sites for extended periods can be used for site evaluations. However, important differences in total contaminant concentrations accumulated have been observed between the wild and transplanted groups. Furthermore, although rearing cultured triploid oysters is widely popular in commercial farming, the difference in contaminant bioaccumulation potential between triploid and diploid cultured oysters is vastly understudied, particularly for organic contaminants such as PAH. This study explores differences in PAH kinetics between transplanted triploid and diploid cultured oysters and wild oysters at a PAH-impacted site during a 6-week field exposure study using novel immunological techniques: antibody-based biosensor technology and immunofluorescence visualization. Conventional chemical analysis of oyster tissue was also conducted for comparison. While differences were observed in the oyster interstitial fluid between the wild and transplanted oysters throughout the study, whole tissue analysis revealed differing trends at each time point. Our findings suggest that insufficient equilibration time may contribute to the differences observed between groups. Furthermore, when combined with visual evidence via immunofluorescence, internal partitioning of contaminants may be an important determinant for total concentrations measured. A better understanding of the differences observed between wild and transplanted oyster groups is necessary for improved biomonitoring. Our study highlights the value in employing novel immunological techniques to explore possible mechanisms driving these differences.

Immunofluorescence Visualization of Polycyclic Aromatic Hydrocarbon Mixtures in the Eastern Oyster Crassostrea virginica.

Bivalve mollusks including oysters have low metabolic potential and are therefore susceptible to accumulating high levels of lipophilic organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Human exposure to PAHs via consumption of this important commercial shellfish can be a serious public health concern in areas where high PAH contamination exists. Previous PAH immunohistochemical studies have been limited to laboratory-based exposures focusing on one or a few individual PAH compounds. To date, such studies have yet to explore PAH accumulation in oysters, known to have some of the highest levels of PAHs across different food products. Using a monoclonal antibody selective for a range of three- to five-ring PAHs, we present a method to detect and localize complex mixtures of PAHs in oyster tissues via fluorescent immunohistochemistry. Observed immunofluorescence intensity followed a similar trend as measured levels of PAHs in oyster interstitial fluid from PAH-contaminated sites and oysters exposed to the water accommodated fraction of crude oil. This method will be valuable in understanding internal partitioning mechanisms of PAH-exposed oysters and will have important applications in studies on PAH distribution in the tissues of additional organisms for environmental, medical, or veterinary purposes. Environ Toxicol Chem 2023;42:475-480. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A novel antibody-based biosensor method for the rapid measurement of PAH contamination in oysters.

Conventional PAH analytical methods are time-consuming and expensive, limiting their utility in time sensitive events (i.e. oil spills and floods) or for widespread environmental monitoring. Unreliable and inefficient screening methods intended to prioritize samples for more extensive analyses exacerbate the issue. Antibody-based biosensor technology was implemented as a quantitative screening method to measure total PAH concentration in adult oysters (Crassostrea virginica) - a well-known bioindicator species with ecological and commercial significance. Individual oysters were analyzed throughout the historically polluted Elizabeth River watershed (Virginia, USA). Significant positive association was observed between biosensor and GC-MS measurements that persisted when the method was calibrated for different regulatory subsets of PAHs. Mapping of PAH concentrations in oysters throughout the watershed demonstrates the utility of this technology for environmental monitoring. Through a novel extension of equilibrium partitioning, biosensor technology shows promise as a cost-effective analysis to rapidly predict whole animal exposure to better assess human health risk as well as improve monitoring efforts.