ARTICLE

THE INCORPORATION OF RADIOACTIVE PROLINE INTO CULTURED CELLS

H. W. Israel ¹, M. M. Salpeter ¹, and F. C. Steward ¹

¹ From the Laboratory of Cell Physiology, Growth, and Development and the Section of Neurobiology and Behavior (Division of Biological Sciences) and the Department of Applied Physics, Cornell University, Ithaca, New York 14850

Cultured carrot explants, stimulated to grow rapidly in a medium containing coconut milk, were labeled with radioactive proline. After an initial period of absorption (8 hr for proline-³H; 24 hr for proline-¹⁴C) the tissue was allowed to grow for a further period of 6 days in a similar medium free from the radioactivity. Samples were prepared for electron microscopy and radioautography at the end of the absorption period and also after the further growth. The distribution of the products from the radioactive proline in the cells is shown by high-resolution radioautography and is rendered quantitative for the different regions of the cells. The results show that the combined label, which was present in the form of proline and the hydroxyproline derived from it, was all in the protoplasm, not in the cell walls. Any combined label that appeared to be over the cell walls is shown to be due to scatter from adjacent cytoplasmic sites. Initially the radioactivity was concentrated in nuclei, even more so in nucleoli, but it subsequently appeared throughout the ground cytoplasm and was also concentrated in the plastids. The significance of these observations for the general concept of a plant cell wall protein and for the special problem of growth induction in otherwise quiescent cells is discussed.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

• Sadava, D., Chrispeels, M. J. (1969). Cell Wall Protein in Plants: Autoradiographic Evidence. Science 165: 299-300 [Abstract]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents