DNA fragmentation and changes of membrane glycosylation in blood cells of chick embryos treated with 5-bromo-2-deoxyuridine during organogenesis

Treatment of 3-day-old chick embryos with 5-bromo-2-deoxyuridine (BrdU) sig nificantly modified membrane glycosylation of blood cells. After the induct ion of DNA lesions and during the DNA repair process, membrane carbohydrate s were more sialylated than in controls whereas the loss of sialic acid, in dicated by increased binding of sialic acid-specific lectins to blood cells , accompanied apoptotic cleavage of DNA. Flow-cytometry analysis after the labeling of cells with lectins thus may contribute to the interpretation of comet assay results. On the other hand, annexin V - generally recommended for identification of dying cells - gave no clue regarding the choice betwe en diverse apoptotic pathways made in BrdU-modified cells.