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. 1999 Dec;10(12):4217–4230. doi: 10.1091/mbc.10.12.4217

Figure 4.

Figure 4

Pancreatic DNase I digestion of Tec element sequences in chromatin early during macronuclear development and the size of the minimal digestion products seen with Tec element probes. (A) Nuclei (a mixture of anlagen and macronuclei) from cells at 17, 22, and 26 h of development were digested with DNase I at 0, 0.1, 0.3, 1, and 3 U/ml DNase I for 10 min, and the DNA was isolated and analyzed on a 1.5% agarose gel as described for Figure 3. Extrachromosomal circular forms of Tec elements are indicated (—EC). (B) “Limit” digests of anlagen prepared from cells at 45 h of development were carried out by extensive treatment with MNase and DNase I. Lane E corresponds to nuclei incubated for 45 min at 37°C to control for endogenous nuclease activity. MNase was added at 5 U/ml for 30 and 45 min, and DNase I was added at 50 U/ml for 10 and 30 min. The marker (M) lane for both blots is a 123-bp ladder with sizes in base pairs indicated.