Meeting Abstract

P3.171  Friday, Jan. 6  The Effects of Manganese and Copper on Mitochondrial Membrane Potential in the Gill of Crassostrea virginica BOISETTE, B.*; DIALEY, F.; DORCE, K.; CATAPANE, E.J.; CARROLL, M.A.; Medgar Evers College, Brooklyn; Medgar Evers College, Brooklyn; Kingsborough Community College, Brooklyn; Medgar Evers College, Brooklyn; Medgar Evers College, Brooklyn

Accumulations of manganese (Mn) or copper (Cu) is characteristic of the neurodegenerative disorders Manganism and Wilson's Disease, respectively. The mitochondrion is a source and target of oxidative stress. Previously we found gill mitochondria from the oyster Crassostrea virginica, treated with Mn or Cu, had impaired oxygen utilization. Oxidative damage causes a loss of mitochondrial membrane potential (MMP) with associated mitochondrial dysfunction. Here we used two fluorescent dyes, TMRM and JC-1, to determine effects of Mn and Cu treatments on MMP. Mitochondria from gill of C. virginica were isolated and treated. For JC-1 we compared fluorescence intensities at 525 nm ex and 590 nm em of Mn treated (50 - 150 mM) mitochondria to that of control. Mn treated showed dose dependant decreases in fluorescence of up to 70%. For TMRM we compared slopes of the 573/564 nm ex, 590 nm em fluorescence intensity ratio. Decreasing slope indicates loss of MMP. Treating isolated mitochondria with Cu resulted in a dose dependant reversal in the slopes from 20 to -20 and from 15 to -3, respectively. Cu was significantly more toxic than Mn and both fluorescent dyes were equally effective in demonstrating that short-term treatments with either Mn or Cu could de-energize gill MMP. This information correlates well with our previous findings on the toxic effects of both Mn and Cu on mitochondrial respiration. Identifying the molecular and cellular mechanisms of metal-induced oxidative stress will provide a better understanding of the pathophysiological features of neurodegenerative disorders associated with metal toxicity.