This Article Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints, Permissions and Rights Citing Articles Citing Articles via Google Scholar Google Scholar Articles by LOVE, D. S. Articles by KONIGSBERG, I. R. Search for Related Content PubMed PubMed Citation Articles by LOVE, D. S. Articles by KONIGSBERG, I. R.

ENHANCED DESOXYRIBONUCLEIC ACID ACCUMULATION AND RETARDED PROTEIN ACCUMULATION IN SKELETAL MUSCLE OF "HYPOPHYSECTOMIZED" CHICK EMBRYOS¹

Division of Chemical Embryology, University of Colorado, School of Medicine Denver, Colorado

Abstract

Hormonal regulation of the chemical composition of developing skeletal muscle was examined by the use of chick embryos in which the prosencephalon was surgically removed at Hamburger-Hamilton stages 10 to 12. Control and operated animals were sacrificed at two-day intervals from the 10th through the 20th day of development and homogenates ofleg muscle prepared and assayed for DNA, RNA and protein nitrogen content.

Muscle fresh weight in the experimental group is normal on the sixteenth day but thereafter increases at a significantly slower rate than in the control group.

On the 16th day of development both the RNA and protein nitrogen content of the leg muscle in the experimental embryos are significantly lower than the control levels. However, although the differences in protein nitrogen content in the two groups becomes progressively larger the initially observed differences in RNA levels is maintained throughout the remainder of the experimental period.

In contrast to the other growth parameters studied DNA accumulation is enhanced in the absence of the derivatives of the prosencephalon. DNA accumulation normally decreases sharply after the 16th day of development. In the experimental group rapid accumulation continues for at least another 48 hours. Consequently, in the operated embryos, the DNA content of the leg musculature is 16% and 22% greater at IS and 20 days respectively than in control embryos.

Footnotes

¹ Supported by grants from the National Science Foundation and the U. S. Public Health Service (Grant #B–549).

Received July 5, 1957.