CELL-CYCLE ANALYSIS AND SYNCHRONIZATION OF THE XENOPUS CELL-LINE XL2

We have determined the length of the cell cycle and its different phas es in a permanent Xenopus tadpole cell line, XL2, Following BrdU label ing, the total length of the cell cycle was estimated as 28 h. The dif ferent phases of the cell cycle, G(1), S, G(2), and M were, respective ly, 14 h, 10 h 45 min, 2 h 30 min, and 54 min. Knowing these parameter s, we were able to develop methods that selectively enrich cells in di fferent phases of the cycle. Treatment with aphidicolin resulted in a S phase block in which more than 85% of the cells showed S phase chrom osomes. Almost 60% of the cells were arrested in mitosis after a doubl e block with aphidicolin/nocodazole or aphidicolin/ALLN (acetyl-leucyl -leucyl-norleucinal) treatment. This synchronization protocol will gre atly facilitate studies of biochemical events associated with specific gene regulation through the cell cycle. Our synchronization protocol does not disturb cell metabolism as the expression of cyclin B-2, duri ng the cell cycle is in agreement with the results obtained with mamma lian cells. (C) 1998 Academic Press.