Fig. 1.

Developmental toxicity of inorganic vs. organic arsenic and mercury. (A) A representative example of the readout from a single worm Development and Activity Test (wDAT) for methylmercury chloride is shown. The y-axis indicates population locomotor activity levels as measured by mean infrared beam interruption values per well from a single experiment, graphed over half hour time increments on the x-axis. L1 through L4 indicates the four larval stages of C. elegans development. There are two separate sets of water controls (L and R), represented by blue and light blue lines for the left and right plates run simultaneously. The horizontal gray arrow from the y-axis indicates the control peak height of the 3rd larval stage (L3). The corresponding times for the two controls to reach the peak height for L3 are 35.5 and 36 h in this experiment. The variability for L3 peak height and timing between controls in separate plates run side-by-side was used as a measure of experimental variability and is shown in 1B-E as ‘0 L-R’. (B-E) Bars and error bars represent the means and standard deviations from four independent wDAT experiments, with the exception of those for 5.0 µg/mL HgCl2 for which there were data from only two of four experiments. (B&D) The delay in the time to reach L3 relative to controls is plotted. (C&E) L3 locomotor activity peak level relative to controls. Not assessed (n/a). T-test p-values *<0.05, ** <0.005. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)