Abstract
A new and rapid procedure for the quantitation of micro quantities of proline by direct densitometry on thin-layer plates is described. Using this method of analysis, the free proline content of tobacco callus cultures exposed to rubber dust in vitro was found to increase by as much as thirty-fold. Neoplastic human cells (HeLa) exposed to rubber dust were found to contain increased quantities of free proline. Thermal black produced an increase in the free proline content of tobacco callus and of HeLa cells in culture. Tobacco callus treated with furnace black showed a marked rise in free proline content (more than eleven-fold at the highest treatment level). Exposure to furnace black produced an increase in the free proline level of HeLa cells.