Automatic monitoring of biochemical parameters in tissue culture. Studies on synchronously growing mouse myeloma cells.

An instrument is described that will maintain a population of mammalian cells at constant cell density while automatically monitoring the growth rate of the culture and the extent of precursor incorporation into a variety of cell products. The apparatus was used in an investigation of cyclic changes in the incorporation of labelled precursors into the DNA, RNA, total protein and myeloma protein synthesized in synchronous cultures of a mouse myeloma line. The incorporation of [(3)H]uridine into trichloroacetic acid-insoluble material reveals a slight periodicity, with maxima and minima corresponding to late S phase and the mitotic phases respectively. The incorporation of [(3)H]lysine into total intracellular protein also shows a slight oscillation, with maxima and minima occurring during the respective G2 and mitotic phases. Cyclical changes in the synthesis of serologically precipitable myeloma protein were found to vary somewhat according to the conditions used to synchronize the cells. In experiments conducted with 4.0mm-thymidine, maximal incorporation of label took place during S phase or early G2 phase. Experiments with 1.0mm-thymidine revealed a significantly less marked periodicity of myeloma protein synthesis.