AJP - Endocrinology and Metabolism, Vol 251, Issue 3 266-E272, Copyright © 1986 by American Physiological Society
Increased formation and keeping of ribosomes during dietary recovery of mouse kidney
S. Iapalucci-Espinoza, J. A. Bur, M. G. Pucciarelli and R. D. Conde
In the kidney of 5-day protein-depleted mice there is a decrease of 23% in
the rRNA mass. When these animals are fed with a complete diet, rRNA
content is restored to its normal value after 24 h of refeeding. The
mechanisms that underlie this phenomenon were studied. It was found that
the activity of rRNA polymerase I in the nuclei of kidneys from refed mice
showed an increase of about twofold compared with the activity in normal
and protein-depleted nuclei. The in vivo incorporation of a large dose
(nontrace) of [14C]orotic acid into rRNA was also twofold enhanced in
kidneys from refed mice. Ribosome degradation (measured by the
disappearance of radioactivity from either ribosomal proteins or rRNA
previously labeled by the injection of NaH14CO3 and [14C]orotic acid to the
mice, respectively) stopped during the 1st day after refeeding. The
estimation of the difference between the rRNA synthesis rate and the net
rRNA increase also demonstrated a decrease in the rRNA degradation rate in
refed mice.
