Fluctuations in glutamine synthetase activity were observed when exponentially dividing cells of Schizosaccharomyces pombe were synchronized by continuous-flow centrifugation. These fluctuations were not seen in a control culture in which cells were allowed to grow asynchronously following filtration. However, when an asynchronous control culture was prepared by allowing cells to pass quickly through the continuous-action rotor without size selection, marked fluctuations in glutamine synthetase activity occurred. It is concluded that when the continuous-flow size selection method of cell synchronization is used, suitable control experiments are essential before any conclusions can be drawn about how enzyme synthesis is regulated during the cell cycle.
Walker, G. M., Thomson, J. C., Slaughter, J. C., & Duffus, J. H. (1980). Perturbation of enzyme activity in cells of the fission yeast Schizosaccharomyces pombe subjected to continuous-flow centrifugation. Journal of General Microbiology, 119(2), 543-546. https://doi.org/10.1099/00221287-119-2-543