It was a finding too striking to be trusted. Elvan Böke, a molecular biologist at the Center for Genomic Regulation in Spain, was studying how immature egg cells in animals, called oocytes, stay healthy in the ovaries before they are fertilized, when the results of a molecular activity assay turned up something she didn’t know was possible.
To survive, almost all cells produce energy in the form of ATP via molecular machines called complexes I, II, III, IV, and V, that rest along the inner membranes of the cells’ mitochondria. But when Böke looked for the activity of complex I in the immature egg cells of African clawed frogs (Xenopus laevis), she couldn’t detect it. “My postdoc repeated the experiment 10 times because we expected something less black and white,” says Böke.
Her group’s findings, described July 20 in Nature, mark the first time scientists have observed that oocytes’ mitochondria ...
