Influence of lithocholic acid on 2-aminoanthracene-induced alterations in DNA synthesis in rat tissues in vivo.

Patterns of DNA synthesis in skin, liver, jejunum and colon of weanling, male Sprague-Dawley rats were monitored for 120 h following the administration of a single carcinogenic dose of 2-aminoanthracene (2-AA) or lithocholic acid (LA) or both. IN the skin, liver and colon 2-AA alone induced a slight inhibition of DNA synthesis during the first 16 h. Simultaneous treatment with 2-AA and LA gave a similar result up to 48 H, beyond which there was a significant enhancement of DNA synthesis.

Basement membrane procollagen is not converted to collagen in organ cultures of parietal yolk sac endoderm.

Basement membrane procollagen biosynthesis was studied in organ cultures of embryonic rat parietal yolk sac endoderm by following [14C]proline incorporation into nondialyzable proteins. After reduction with 2-mercaptoethanol the 14C-proteins synthesized were characterized by agarose gel filtration and disc electrophoresis in the presence of sodium dodecyl sulfate. The labeled procollagen was identified by its content of hydroxy[14C]proline, its sensitivity to digestion with bacterial collagenase, and its resistance to digestion with pepsin.