Ara-C에 의한 내재복제의 유도

Abstract

Endoreduplication is defined that the chromosomes replicate two or more times between two mitosis. If two replications have occurred, the chromosome in a subsequent mitosis consist of four chromatids, what is called diplochromosomes. It may occur in normal and tumor tissue spontaneously. To invastigate the induction of endoreduplication human lymphocytes and EBV induced transforned B cells were treated with DNA synthesis inhibitor, cytosine arabinoside (ara-C). If the endoreduplicated cells originate from cells cotaining replicated DNA segments, the diplochromosomes of endoreduplicated cells should be differentially stained depending on whether or not be incorporated BudR. In the frequency of endoreduplication after treatment with ara-C, the kinetic data revealed differently between normal peripheral lymphocytes and EBV induced transformed B lymphocytes; the former is 5.5% with 8 hours duration of ara-C treatment, the letter is 2.5% with 16 hours treatment. In the case of SCE frequency, shorter duration of ara-C treatment (4h, 8h) showed high frequency of SCE. The data suggest that endoreduplicated cells originate from cells blocked at the G2 stage of the cell cycle.