“Life time” of AluI inside Glycerol-Induced Vesicles in CHO Cells

Recently we have shown that the restriction endonuclease (RE) AluI is effectively internalized by Chinese hamster ovary (CHO) cells in the presence of hypertonic solutions of glycerol. The uptake of AluI is mediated by the formation of vesicles which upon addition of isotonic medium break and liberate AluI in the cytoplasm (Johannes et al. 1992). The induction of chromosomal aberrations by AluI is more effective in the presence of 2.2 M than of 1.1 M glycerol (Johannes and Obe 1991). We assume that the amount of vesicles formed is dependent on the hypertonicity of the glycerol-containing treatment solution. More vesicles would allow more AluI molecules to enter the cytoplasm and in consequence this would lead to more aberrations. In order to get information about the “life time” of AluI inside the vesicles we stabilized the vesicles by posttreatment with glycerol and found that there is a decrease of aberration frequencies with the duration of posttreatment. Our experiments indicate that the “life time” of Alul inside of cytoplasmic vesicles can be about 3h.