Summary: ation for FISH as 60% (0.75 0.95 0.85). The
validity of this estimation was demonstrated when
the same calculation was applied to GFP experi-
ments. The maximum detection of acentric minichro-
matid dissociation was estimated as 39%, a value
very similar to the actual measured value.
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17. Supported in part by NIH grant GM41718. We thank
M. K. Raghuraman and R. Ciosk for plasmids and C.-M.
Fan, V. Guacci, P. Meluh, and members of the Ko-