Berwind P. Kaufmann

Organization of the Chromosome

The observational and experimental results presented here constitute another chapter in a continuing research program that is directed toward an understanding of patterns of organization of chromosomal materials. Evidence has been sought over the years at various levels of analysis, beginning with descriptive cytology, progressing into the areas of experimental and analytical cell research, and extending in recent months to the realm of fine detail afforded by the resolving powers of the electron microscope. Attention has been focussed throughout on the chromosomes of higher plants and animals, because their large size favored microscopic examination and because they offered the prospect of correlating chromosome activity with developmental processes. This progress report includes a brief examination of the background information accumulated in the earlier studies and then attempts to fit the more recent findings into that frame of reference.

The degradation by ribonuclease of substrates other than ribonucleic acid.

These experiments support the premise which is the basis for cytochemical procedures that employ ribonuclease for the identification of ribonucleic acid, namely, that the substrate specifically degraded by ribonuclease is ribonucleic acid. The reduction in Feulgen stainability of chromatin effected by ribonuclease has been shown to be due to an intracellular deoxyribonuclease, which hydrolyzes intracellular deoxyribonucleic acid only after ribonucleic acid has been removed. The degradation of apurinic acid by ribonuclease can be duplicated by other proteins.