Meeting Abstract
The endocrine disruptor nonylphenol (NP) is a pervasive aquatic pollutant whose detrimental effects on marine organisms (e.g., growth, reproductive, developmental and metabolic impairments) can be attributed to both its estrogenic activity, as well as other unrelated toxic properties. The goal of this study was to determine how exposure to NP influenced immune function in the Pacific oyster (Crassostrea gigas) by measuring total hemocyte counts (THC) and immune-gene expression following a bacterial infection. We exposed oysters to NP at high (100μg/L), low (2μg/L) or control doses for 7d, then experimentally infected oysters with Vibrio campbellii. After 24h, hemolymph samples were collected for immediate determination of THC, whereas gill, mantle and hemocyte tissues were collected for the subsequent qPCR analysis of nine immune genes (bigdef1-3, bpi, galectin, lectin, lysozyme, transglutaminase and timp). We found that bacterial infection resulted in a significant increase in THC in the control oysters, but this response was abated in both low and high NP exposure groups. We also confirmed that a number of genes were significantly responsive to bacterial injection (in all tissues: lysozyme and timp; hemocytes: bigdef2; mantle: galectin, transglutaminase, bigdef2 and bpi); and of these, infection-induced expression changes in galectin and tranglutaminase (in mantle tissue) were also repressed by low dose NP exposure. Other times NP alone caused significant changes in the relative mRNA levels (i.e., bpi, lectin and bigdef1 in the mantle, and bpi and galectin in the gill tissue). Our results suggest that exposure to NP (and particularly the low dose) does have the potential to alter the cellular and transcriptional level immune response to bacterial infection in C. gigas.
