Figure 4.

Nick-translation labeling of fluid-fixed lambda bacteriophage DNA molecules using a fluorochrome-bearing nucleotide (R110-dUTP). DNA molecules fixed onto derivatized glass surfaces before labeling by nick-translation. (A) Overview of a spot (edge) using a 16× objective. (B) The same spot portion imaged with a 100× objective. (C) Counter-staining with YOYO3 (separate experiment). The absence of heavily punctated staining patterns along molecule backbones indicates the general absence of gaps, or double-strand breaks. Staining is not robust because of fluorochrome-fluorochrome interaction. (Bars: 4 μm.)