QUANTITATIVE ASPECTS OF DEOXYRIBOSE NUCLEIC ACID (DNA) METABOLISM IN AN AMICRONUCLEATE STRAIN OF TETRAHYMENA

¹ Department of Zoology, Columbia University, New York 27, N. Y.

1. In a mass culture of Tetrahymena pyriformis H which has stopped growing, the macronuclei contain approximately twice as much DNA as do newly divided macronuclei in a logarithmically growing culture.

2. Non-clonal cells show considerable variability as to DNA content and generation time.

3. Cells in small clones show close similarity as to DNA content and generation time.

4. Duplication of DNA occurs during an intermediate part of interphase, starting some time after the end of the previous cell division, and reaching completion a considerable period of time before the next division begins.