Analysis of chromatin structure near Ds-bar cassettes from lines with a transposed or non-transposed Ds-bar cassette. Intact nuclei from plants with (i.e. TNP A8-1-85) or without (i.e. nTNP A8-1-5) transposed Ds-bar were treated with DNaseI for 0 to 20 min. DNA was isolated, digested with BglI to obtain fragments of a specific reference size (1.9 kb), electrophoretically separated, blotted, and hybridized with probe C (Fig. 4B). Naked DNA (no intact chromatin) from both plants, treated for 2 min with DNase I, served as a control.