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Figure 3. Blue light suppressed mitochondrial activity in Balb/c 3T3 fibroblasts. Balb/c fibroblasts were chosen for further study because they were most sensitive to blue light (Figs. 1, 2). Photomicrographs (A, B, C, and D, 50x, bar = 500 µm) of cells (fixed with 4% formalin) 72 hrs post-exposure to blue light from QTH (B, 2 min, 60 J/cm2), PAC (C, 30 sec, 60 J/cm2), or Laser (D, 10 sec, 5 J/cm2) sources (Table). No-light controls are shown in A. Presence of the blue formazan dye is indicative of active mitochondrial succinate dehydrogenase (SDH). Cells in the no-light controls (A) show high levels of formazan, whereas light-exposed cells (B,C,D) show little or no formazan, indicating inactive SDH. TEM (E,F) of identically treated (fixed and processed as described in METHODS) cells 6 hrs post-QTH exposure show evidence of degenerating mitochondria (DM, in panel F) vs. normal mitochondria (M) in no-light controls in panel E. Light-exposed mitochondria in F show loss of inner mitochondrial membrane structure and a dark staining of the outer membrane. TEM micrographs courtesy of Dr. Franklin Tay, University of Hong Kong.
