EFFECTS OF EXPOSURE TO LEAD (Pb) AND OTHER DIVALENT CATIONS ON NEUROMASTS OF THE POSTERIOR LATERAL LINE IN EMBRYONIC ZEBRAFISH**

Lead (Pb) is an environmental toxin known to have detrimental effects on development of the central nervous system leading to impairment of cognitive function and learning and behavioral disorders. We have previously examined the effects of exposure to Pb on the development of the posterior lateral line (PLL), an important sensory system, in embryonic zebrafish (Danio rerio). Our results suggested that lead acetate and lead chloride accelerated PLL development. However, the rate of PLL development with sodium acetate and sodium chloride (used as a controls) was also typically increased suggesting that the alteration in the rate of PLL development might be more dependent on alteration of ion concentrations than an effect specific to lead. In this study, we attempted to separate any toxic effects of Pb and other ions (primarily divalent cations) by examining whether exposure to these cations altered the ability of the neuromasts of the lateral line to take up 2-[4-(Dimethylamino)styryl]-1-ethylpyridinium iodide (DASPEI), a fluorescent vital dye that will stain hair cell mitochondria. Preliminary data suggest that Pb (both the acetate and chloride forms) significantly inhibit DASPEI-staining of neuromasts. Calcium chloride and sodium acetate also significantly inhibit staining whereas staining following treatment with the acetate and chloride forms of zinc, cobalt as well as NaCl were not significantly different from that of control.