The measurement of spatial precursor distributions in cell culture

The distribution of incorporated radioactive precursors, for both DNA and protein synthesis, has been measured with a resolution of about 1 mm in cell cultures, using a scanning technique. Either gamma radiation and X-rays or beta radiation (electrons) were detected by scintillation detectors. Spectrophotometer measurements with a resolution of 1 mm gave good estimates of cell density changes. Glioma cell colonies were used to compare this technique with autoradiography. Variables such as the density of labelled cells and percentage of labelled cells could be estimated rather accurately. For example, an increased cell density was correlated to a local decrease in DNA synthesis.