The frequency distribution of DNA content of human sperm was measured in an automated flow microfluorometer. The flow method measures the DNA content by quantifying the amount of fluorescence emitted by the fluorescent Feulgen stained DNA of single sperm cells suspended in microdroplets. The variability in the mean value for the haploid amount of DNA in sperm from 15 randomly chosen donors was ...

We have measured the nuclear DNA content of the major life cycle stages of Trypanosoma congolense, in two clones of geographically distant origin. We find that nuclear DNA content in epimastigote, mammalian blood-stream and metacyclic forms is constant and that the nuclear DNA contents of the two clones were 0.1 pg and 0.09 pg, respectively.

The range of variability in the population distribution characteristics of sperm DNA content was surveyed in a selected group of donors. The donors included identical twins, carriers of chromosomal translocations, and oligospermics. The DNA content of sperm was measured individually in an automated cytofluorometer. In contrast to normal donors with high sperm counts and relatively constant moda...

Using cytophotometry the mean macronuclear DNA content of the ciliate Tetrahymena was found to be variable in two cell lines examined. While environmental changes (different culture fluids, temperature shifts) influence the mean DNA content of at least one of the two cell lines, spontaneous changes of the means are observed in both lines. The mean DNA contents of cultures maintained permanently...

Measurements of the micronuclear DNA content of clones with assumed different degrees of micronuclear ploidy confirmed the triploid nature of one clone. The micronuclear DNA content of a presumptive haploid clone was found to be slightly higher than expected, whereas one of two aneuploid clones had an unexpectedly low micronuclear DNA content. The macronuclear DNA content of cells with macronuc...

One of the long-standing mysteries in genomic evolution is the observation that much of the genome is composed of repetitive DNA, resulting in inter- and intraspecific variation in nuclear DNA content. Our discovery of a negative correlation between nuclear DNA content and flower size in Silene latifolia has been supported by our subsequent investigation of changes in DNA content as a correlate...

The macronucleus of Paramecium divides amitotically, and daughter macronuclei with different DNA contents are frequently produced. If no regulatory mechanism were present, the variance of macronuclear DNA content would increase continuously. Analysis of variance within cell lines shows that macronuclear DNA content is regulated so that a constant variance is maintained from one cell generation ...