DNA METHYLATION DURING ANTHERIDIAL FILAMENT DEVELOPMENT AND SPERMIOGENESIS IN CHARA-VULGARIS (CHAROPHYCEAE) ANALYZED BY IN-SITU NICK-TRANSLATION DRIVEN BY METHYLATION-SENSITIVE RESTRICTION ENZYMES

DNA of Chara vulgaris thalli contains target sequences for the methyla tion-sensitive restriction enzymes, Sau3A, HpaII and MspI. These enzym es were used with the in situ nick-translation radioactive technique t o evaluate by grain counting in autoradiograms changes in cytosine met hylation during antheridial filament development and spermiogenesis. I n successive generations of dividing antheridial filaments the lever o f DNA methylation gradually increases, then decreases slightly in the early stages of spermiogenesis. Spermatozoids display the highest leve l of DNA methylation.