Meeting Abstract
Endocrine disrupting compounds (EDC’s) are chemicals that can interfere with hormone signaling pathways and are now recognized as pervasive in estuarine and marine waters. One emerging EDC in California’s coastal waters is the xenoestrogen 4-nonylphenol (4-NP), which has been shown to impair reproduction, development and in some cases immune function of marine invertebrates. To further investigate effects of 4-NP on marine invertebrate immune function, we conducted molecular-level characterizations of gene transcript changes in the Pacific oyster (C. gigas) following bacterial exposure. To quantify these effects we exposed oysters to dissolved phase 4-NP at high (100 μg/L) or low (2 μg/L) concentrations for 7 days, and then experimentally infected (via injection into the adductor muscle) the oysters with the marine bacterium Vibrio campbellii. After 24 hours, tissues (gill, mantle and hemocyte) were dissected and flash frozen in liquid nitrogen. Quantitative real-time RT-PCR was used to measure relative transcript abundances for genes known to respond to bacterial challenge (BIGdef1-3, BPI, DefH1-2, galectin, lectin2, lysozyme, transglutaminase, and TIMP). Thus far we have determined that exposure to 4-NP has a significant effect (p<0.06) on relative mRNA levels of BPI and galectin in the gill tissue with the most substantial differences occurring in the low dose for both bacterially-infected and -naïve oysters. Furthermore, bacterial infection alone has effects (p<0.06) on relative mRNA levels of TIMP, transglutaminase, and lysozyme across all 4-NP concentrations evaluated. These results suggest that exposure to 4-NP can alter the transcriptional responses of immune-related genes to bacterial infection in C. gigas.
