Chinese hamster cells were synchronized by the Colcemid-selection system. In cells with a division cycle time of 11.5–12 hr, the activity of the enzyme lactate dehydrogenase (LDH) underwent marked oscillations with a 3.5-hr period. Precipitation of labeled LDH enzyme with specific antibody indicated that the enzyme activity changes were the result of intermittent enzyme synthesis and relatively constant degradation. Inhibition of normal DNA replication with 4 mM of thymidine, while reducing the amount of new enzyme synthesized, did not prevent oscillations from occurring. Similarly, actinomycin D (AcD) added at the time of synchronization allowed some new enzyme synthesis to proceed in an oscillatory manner. LDH synthesis went on at nearly normal rates when AcD was added in the middle of S phase. However, addition of cycloheximide to cultures at any time in the cycle caused an immediate drop in levels of activity and in enzyme protein. The half-life of LDH, calculated either from loss of enzyme activity or precipitable radioactivity in cycloheximide-treated cultures, was between 2 and 2.5 hr.
Article| November 01 1969
TEMPORAL ORDER IN MAMMALIAN CELLS : I. The Periodic Synthesis of Lactate Dehydrogenase in the Cell Cycle
Robert R. Klevecz
From the Department of Biology, City of Hope Medical Center, Duarte, California 91010
Received: March 10 1969
Revision Received: May 14 1969
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1969 by The Rockefeller University Press.
Robert R. Klevecz; TEMPORAL ORDER IN MAMMALIAN CELLS : I. The Periodic Synthesis of Lactate Dehydrogenase in the Cell Cycle . J Cell Biol 1 November 1969; 43 (2): 207–219. doi: https://doi.org/10.1083/jcb.43.2.207
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