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Lesch‐Nyhan mutation: The influence of population density on purine phosphoribosyltransferase activities and exogenous purine utilization in monolayer cultures of skin fibroblasts
Author(s) -
Wood Stephen,
Pinsky Leonard
Publication year - 1972
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040800105
Subject(s) - adenine phosphoribosyltransferase , hypoxanthine , hypoxanthine guanine phosphoribosyltransferase , hypoxanthine phosphoribosyltransferase , purine , biochemistry , population , biology , microbiology and biotechnology , purine metabolism , mutant , subculture (biology) , phosphoribosyltransferase , fibroblast , chemistry , in vitro , enzyme , gene , botany , demography , sociology
In extracts of normal and Lesch‐Nyhan (LN) heterozygous skin fibroblast monolayer cultures, hypoxanthine‐guanine (H‐G) and adenine (A) phosphoribosyltransferase (PRT) activities are correlated. These activities vary concomitantly during the life cycle of a culture: Peak activities occur during exponential growth. The ratio of H‐GPRT to APRT activity can manifest heterozygosity at the LN locus when H‐GPRT activity, per se, is close to and unreliable different from the normal range. If 2 or 8 × 10 4 cells are planted per 35 mm petri dish, a strain with clearly heterozygous levels of H‐GPRT activity in its cell extract may not reveal its genotype by simultaneous measurement of adenine and hypoxanthine incorporation into its acid‐insoluble fraction one day after subculture. In contrast, a 1:1 coculture of normal and mutant cells yields the ratio of adenine to hypoxanthine incorporation expected from the behavior of each cell type separately. In heterozygous cultures at the higher population density, the incorporation of hypoxanthine relative to adenine is 28% greater than in those at the lower population density. A 1:1 mixture of normal and mutant cells exhibited a 20% increase in the relative incorporation of hypoxanthine over the same four fold increase in population density. These observations appear to provide a quantitative expression of the phenomenon of metabolic cooperation between contacting H‐GPRT‐negative and H‐GPRT‐positive cells.