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Stimulation of uptake of tritiated thymidine into mouse marrow cells in culture by a factor from L‐cell conditioned medium
Author(s) -
Austin P. E.,
McCulloch E. A.,
Till J. E.
Publication year - 1972
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040790204
Subject(s) - thymidine , stimulation , in vitro , microbiology and biotechnology , biology , bone marrow , cell culture , trypsin , biochemistry , endocrinology , immunology , enzyme , genetics
Uptake of 3 H‐thymidine into suspension cultures of mouse marrow cells was stimulated by the addition of serum‐free conditioned medium harvested from cultures of mouse L‐cells. Characterization of the “conditioning factor activity” (CFA) by gel filtration, ion exchange chromatography, velocity sedimentation, polyacrylamide gel electrophoresis and susceptibility to trypsin digestion indicated that the CFA detected by stimulation of 3 H‐thymidine uptake is the same as the CFA detected previously by its ability to stimulate colony formation by marrow cells in vitro . The 3 H‐thymidine uptake assay was used to investigate the kinetics of disappearance of CFA as a function of time in the presence of mouse marrow cells. The CFA recoverable from the cultures decreased rapidly during the first day, and approached background levels by the fifth day. There was no evidence of inhibitory substances in the depleted media. Even if the cultures continued to receive fresh conditioned medium at daily intervals, 3 H‐thymidine uptake decreased sharply after the fifth day, indicating that the marrow cells had lost their capacity to respond to CFA.