FIG. 1.

ROS levels increase throughout the cell cycle and oscillate each cell division. (A) Early G₁ to S phase fractions of Jurkat cells were synchronized by centrifugal elutriation and then analyzed for cell size (forward scatter), mitochondrial content (Mitofluor green), and ROS levels (H₂DCFDA). ROS levels increase from early G₁ to S phase considerably in comparison to cell size and mitochondrial content. (B) G₂/M Jurkat cells were synchronized by centrifugal elutriation, replated, and either not treated or treated with the antioxidant tempol. Cells were then analyzed for ROS levels at 0, 7, 11, and 16 h. ROS levels were highest in the G₂/M population, then dropped as control cells transited into early G₁, and increased as they progressed towards S phase. (C) ROS levels in untreated G₁- and G₂/M-synchronized T98G cells in comparison to the dramatic difference in ROS levels known to cause DNA damage. (D) Asynchronous T98G cells treated with the antioxidants tempol or DDC show a reduction in ROS levels in comparison to control ROS levels.