FIG. 15.

DNA content distribution of testes from sir2α null mice indicates that all stages of spermatogenesis are present. Single-cell suspensions were created from the testes of 7-month-old wild-type (upper panel) and sir2α null (lower panel) animals. Cells were fixed and stained with 4′,6′-diamidino-2-phenylindole before analysis by flow cytometry for DNA content per cell. The peaks corresponding to 1n, 2n, and 4n genomes are shown. Mature sperm stained less efficiently than expected and formed the broad peak at the left of the pattern. Replicating cells have a DNA content between 2n and 4n.