Abstract
Hydrogenosomes are found in organisms that lack typical mitochondria. Cardiolipin is a phospholipid located exclusively in bacterial membranes and the inner membrane of mitochondria. Here we show, by cell fractionation, thin-layer chromatography, high-pressure liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry that hydrogenosomes of Tritrichomonas foetus, a cattle vaginal parasite, contain cardiolipin, which is strong evidence for its endosymbiotic origin.