MITOCHONDRIA OF MOUSE FIBROBLASTS L-929 CULTURED IN A LIPID- AND PROTEIN-FREE CHEMICALLY DEFINED MEDIUM

1. Mitochondrial lipids of mouse fibroblasts of the substrain Lp3, one of the sublines of L-929 which had been cultured in the lipid-free and protein-free synthetic medium DM-120 for 9 years, were analyzed.2. Essential fatty acids were not detected but monounsaturated fatty acids were found to have increased in the mitochondria. The presence of coenzyme Q, inositol, and vaccenic acid was confirmed.3. By the addition of linoleic acid into DM-120, considerable changes were induced in the fatty acid composition of each phospholipid fraction, whereas the proportional ratios among phospholipids were little influenced.4. Mitochondrial functions, such as oxidative phosphorylation in situ, ATPase [EC 3.6.1.3] activity and electron transport by cytochromes, were kept unchanged in the lipid-free synthetic medium. The oxidative phosphorylation in the isolated mitochondria, however, was found unstable, suggesting that it awaits further investigation. © 1969 BY THE JOURNAL OF BIOCHEMISTRY.