FIG. 4.
Chromosomal DNA extracted from spores of strain WN356 exposed to full-spectrum sunlight on 21 and 22 July 1998 was electrophoresed through a 0.8% neutral agarose gel (A) and a 0.8% alkaline agarose gel (B). Spores were not exposed to light (lanes 1 and 2), exposed to full-spectrum sunlight (6.7 × 105 J of UV-A radiation per m2 plus 2.9 × 105 J of UV-B radiation per m2) (lanes 3 and 4), exposed in parallel to only UV-A sunlight (2.68 × 105 J/m2) (lanes 5 and 6), or exposed in parallel to only heat (lanes 7 and 8). Isolated DNA was treated with Endo V before electrophoresis (lanes 2, 4, 6, and 8). Lanes M contained molecular weight markers (1-kb ladder; the arrowheads indicate the positions of 12- and 1-kb markers).