Evaluation of mercury mediated in vitro cytotoxicity among cell lines established from green sea turtles

Abstract

In vitro cell cultures are currently tested for their application as a biological tool for enhanced monitoring and field evaluation of environmental toxic chemical pollution. Here cell lines established from green sea turtles (GSTs) were comparatively tested for their cytotoxic responses to mercury chloride (HgCl2) exposure and also their potential use as a biological tool for effective monitoring and screening of mercury contamination in environmental waters. Following a 24-h exposure to different concentrations of mercury solution, marine turtle cells were evaluated for their cytotoxic responses using three different endpoint bioassays: tetrazolium salt reduction (MTT), neutral red uptake (NR), and Coomassie blue (CB) methods. Cytotoxic sensitivities of GST cell lines to HgCl2 were determined and compared basing on their 50% inhibition concentration (IC50) values calculated from these tests. These marine turtle cells share a very different pattern of cytotoxic sensitivities and reactions to inorganic Mercury. Among these nine turtle cell lines, turtle liver cells (GST-LV) appear to be the most tolerant one to mercury exposure while turtle lung cells (GST-LG) exhibit to be the most sensitive one. Results from this in vitro study correlate well with in vivo examination of mercury concentration in the tissues of marine turtles and are also validated and ascertained by calculated regression equations showing a significant correlation (P<0.01) between these test methods. This study also reveals the cytotoxic effect of inorganic mercury on in vitro green turtle cells and also shows GST-LG to be a cell line with potential application in field monitoring and assessing mercury contamination as a bioindicator.