Polypeptide hormone binding sites in vivo: initial localization of 125I-labeled insulin to hepatocyte plasmalemma as visualized by electron microscope radioautography

The rationale of the specific-binding assay was applied to the detection of the liver insulin receptor in vivo. Quantitative electron microscope radioautography indicated that, 3 min after an intraportal injection, 125I-insulin was exclusively located to the hepatocyte plasmalemma.

Influence of dimercaprol on the early hepatic uptake of 111In-bleomycin in the BALB/c mouse

Dimercaprol (BAL) administered 1 hr before 111In-bleomycin in the normal BALB/c mouse produced an early preferential hepatic loading of 111In-bleomycin without a loading of the spleen, skin, bone, or muscle. Liver-to-muscle ratios were increased about threefold under the influence of BAL. Liver (c BAL)/liver (s BAL) ratios also increased threefold at 3 hr whereas relative muscle uptake remained at about unity. Indium-111 chloride (colloid, pH 6.5) used as a control did not show a similar increase. The findings suggest that the kinetics and distribution of 111In-bleomycin in the normal BALB/c mouse can be influenced by pretreatment with BAL.

Isolation and characterization of a mutant of Salmonella typhimurium deficient in a major deoxyribonucleic acid polymerase activity

A mutant of Salmonella typhimurium strain LT2 that is deficient in a major deoxyribonucleic acid (DNA) polymerase activity has been isolated and characterized. This mutant resembles the pol mutants of E. coli in that it has low DNA polymerase activity and it is sensitive to methyl methane sulfonate as well as ultraviolet irradiation. Revertants selected for methyl methane sulfonate resistance are no longer sensitive to ultraviolet irradiation and contain normal DNA polymerase levels. No direct role in replication can be ascribed to this polymerase activity since cells grow well in its absence. In addition, the LT2 plasmid has been shown to exist in the mutant strain.