DiS-C3(3) monitoring of in vivo mitochondrial membrane potential in C. elegans.

The mitochondrial respiratory chain plays a crucial role in cellular and organismal health. In addition to being the major source of energy for most cells, mitochondrial respiratory chain function regulates or modulates redox and metabolite homeostasis, apoptosis and the generation of reactive oxygen species. In order to measure the relative in vivo mitochondrial membrane potential of different strains of the nematode, Caenorhabditis elegans, we have developed a fluorescence assay using the cationic, lipophilic carbocyanine dye, diS-C(3)(3). We demonstrate that two complex I-deficient mutants have significantly lower mitochondrial membrane potentials in vivo than wild type animals. Our fluorescence assay will enable us to better dissect and understand the complex phenotypic consequences of mitochondrial dysfunction.