X-ray microanalysis has been used to study changes in concentration of P, S, Cl Na and K in synchronized HeLa S3 cells in g1 phase infected with Vaccinia virus. No dramatic redistribution of elements between nucleus and cytoplasm was demonstrated during the first 6 h post-infection, during which time viral shut-off of host protein synthesis occurred. [Cl] increased relative to [Na] and [K] during the first 3 h post-infection. The magnitude and direction of change in [K] and [Na] (from

more »

... ely 10 cells/analysis) was compared with data previously obtained by flame photometry (from approximately 10(6) cells/analysis) and found to be remarkably parallel.