Rhodoquinone carries electrons in the mammalian electron transport chain.

Ubiquinone (UQ), the only known electron carrier in the mammalian electron transport chain (ETC), preferentially delivers electrons to the terminal electron acceptor oxygen (O). In hypoxia, ubiquinol (UQH) diverts these electrons onto fumarate instead. Here, we identify rhodoquinone (RQ), an electron carrier detected in mitochondria purified from certain mouse and human tissues that preferentially delivers electrons to fumarate through the reversal of succinate dehydrogenase, independent of environmental O levels.

Chromosome evolution screens recapitulate tissue-specific tumor aneuploidy patterns.

Whole chromosome and arm-level copy number alterations occur at high frequencies in tumors, but their selective advantages, if any, are poorly understood. Here, utilizing unbiased whole chromosome genetic screens combined with in vitro evolution to generate arm- and subarm-level events, we iteratively selected the fittest karyotypes from aneuploidized human renal and mammary epithelial cells. Proliferation-based karyotype selection in these epithelial lines modeled tissue-specific tumor aneuploidy patterns in patient cohorts in the absence of driver mutations.