As measured by a decreased rate of dissociation, lac repressor binds 10-times tighter to 5-bromodeoxyuridine-substituted lac operator than it does to normal lac operator. This result is obtained both in the absence and in the presence of isopropylthiogalactoside, an inducing ligand. These data are significant with regard to the mechanism of sequence-specific protein-DNA interaction, and also su...

Hepatocyte cultures derived from 15-day foetal rats produce the liver form of pyruvate kinase (EC 2.7.1.40) only after 3 days of culture. The appearance of the liver form of the enzyme can be blocked by the addition of 5-bromodeoxyuridine on day 2 of culture, but not by addition on day 3 of culture. The reversibility of the action of 5-bromodeoxyuridine was shown when the inhibitor was added on...

Chondrocytes grown in cell culture from micromelic chick sterna and 5-bromodeoxyuridine-treated normal cells showed reduced incorporation of sulfate into hyaluronidase-sensitive material as compared to normal chondrocytes. Proteochondroitin sulfate synthesized by normal embryonic chick chondrocytes in cell culture was heterogeneous on chromatography. The major chromatographic component was spec...

In vitro uptake of bromodeoxyuridine and expression of proliferating cell nuclear antigen (PCNA) were evaluated histochemically in rectal mucosa of control subjects and subjects with colorectal neoplasia in large intestine adenomas and adenocarcinomas. Both labeling indices progressively increased along the path of tumor progression, as did the difference between them (PCNA labeling indices wer...

Six Burkitt's lymphoma-derived lines were more resistant to methyl methanesulfonate than were six lymphoblastoid lines derived by in vitro transformation as measured by cloning ability in soft agar. The differences were due to cell response rather than to reactivity. Lymphoblastoid lines were also more sensitive to [3H]thymidine incorporated along with bromodeoxyuridine than were the lymphoma l...