BAX/BAK Independent Cell Death Figure 9. BH3 peptides induce a decrease in mitochondrial aspect ratio of Bax2/2/Bak2/2 MEFs. (A) Electron micrograph at 20006 of Bax2/2/Bak2/2 MEFs treated with mutant BID BH3 peptide (100 mM). 60006 magnification of indicated area. (B) Electron micrograph at 20006 of Bax2/2/Bak2/2 MEFs treated with BID BH3 peptide (100 mM). Indicated regions are at 60006magnification. (C) Mitochondrial length was determined by analyzing the aspect ratio (AR), (length of major axes/ minor axes). BID treatment resulted in a decrease in AR ratio. P value = 0.0001. Student’s unpaired t test was used to assess for statistical significance. doi:10.1371/journal.pone.0005646.g009 membrane potential in the absence of BAX and BAK. Loss of mitochondrial membrane potential can be an initiating event for induction of cell death [32]. Previous studies have indicated that mitochondrial fission can result in loss of mitochondrial membrane potential [7]. Depolarized mitochondria as a result of excessive fission have lower probability to refuse, which therefore leads to an PLoS ONE | www.plosone.org 11 May 2009 | Volume 4 | Issue 5 | e5646