Figure 2

Copy number determination for lines PD3994 and PD5122. Panels a, c, e, g, and i are agarose gel images of Dpn I, Mbo I, and Sau3A I digested DNA from PD3994, PD5122, and N2 (control) animals. Below each agarose gel is the corresponding Southern blot (b, d, f, h, j). pPD98.38 is a plasmid from which the probe (808 bp of the C. elegans 5S rDNA/SL1) was synthesized. The slight smearing seen in ethidium bromide stained gels for N2 (a and e) likely resulted from non specific activity of Dpn I. Compared to fully methylated GATC, Dpn I can cut non-methylated GATC 1,000 fold slower and hemimethylated GATC 60 fold slower (Derek Robinson, New England Biolabs, personal communication).