DNA of Chara vulgaris thalli contains target sequences
for the methylation-sensitive restriction enzymes, Sau3A,
HpaII and MspI. These
enzymes were used with the in situ nick-translation radioactive
technique to evaluate by grain counting in autoradiograms changes in
cytosine methylation during antheridial filament development and
spermiogenesis. In successive generations of dividing antheridial
filaments the level of DNA methylation gradually increases, then decreases
slightly in the early stages of spermiogenesis. Spermatozoids
display the highest level of DNA methylation.
