167425.fig.004a
(a)
167425.fig.004b
(b)
167425.fig.004c
(c)
Figure 4: Effects of low-dose UVA on fibroblast cell cycle. PI staining using single parameter histogram represented the change of cell cycle in each group. DNA histogram offered peak distribution. The ordinates represented cell number, and the abscissa represented PI intensity. The DNA peak near 50 (2C) in the abscissa represented the diploid G0/G1 phase; the DNA peak near 100 (4C) in the abscissa represented the tetraploid G2/M phase; the DNA peak between 2C and 4C represented diploid to tetraploid S phase; the DNA peak before 2C represented hypodiploid DNA fragments indicating cell apoptosis. (a) Phase distribution of cell cycle of SIG fibroblasts. The proportions of G0/G1 phase, S phase, and G2/M phase were 85.01%, 6.49%, and 8.49%, respectively. (b and c) Repeated low-dose UVA irradiation altered the phase distribution of cell cycle. When the dosage accumulated to 28.8 J/cm2, the proportions of G0/G1 phase, S phase, and G2/M phase were 84.09%, 12.95%, and 1.95%, respectively (b); when the dosage accumulated to 115.2 J/cm2, the inhibition of cell cycle was observed apparently. The proportions of G0/G1 phase, S phase, and G2/M phase were 93.97%, 5.37%, and 0.66%, respectively (c).