Alkaline Phosphatase Activity of L-M Mouse Cells and Variants.

Abstract

Summary Two types of population selection pressure viz., simplification of the nutritional environment and ability to survive and grow in vivo, were seen as effecting the distribution of alkaline phosphatase activity in L-M strain mouse fibroblasts and derived variants. L-M cells growing in medium 199 supplemented with peptone have moderate AP activity as determined quantitatively: histochemically, the population includes a number of cells with little or no activity as well as cells with moderate to high activity. A variant of these cells growing in a chemically defined medium has no measurable AP activity. Distinct differences were noted between these 2 lines when their in vivo growth capacity in inbred C₃H mice was studied: in the line having moderate AP activity, there is a selection of the population resulting in nodules comprised of cells of high AP activity, with these nodules appearing within 7-10 days in a large percentage of the animals: In the line having no initial enzyme activity, there was no such selection for AP, and nodules appeared no earlier than 3 weeks after injection and in a smaller percentage of animals.