Abstract
The rates of DNA chain growth in four Bloom syndrome (BS) and one normal B-lymphoblastoid cell lines (B-LCLs) were studied using DNA fiber autoradiography. Four BS cell lines were classed into two groups, one with high sister chromatid exchange (SCE) character, the other with normal (low) SCE. Hot pulse warm chase (hot-warm) labeling was used to measure the replicon sizes, and pulse labeling with three different durations (30, 60 and 120mins) was used to estimate DNA chain growth rates. There was no significant difference in the rate of chain growth per minute among all of the cell lines studied. The finding that there is no difference of DNA chain growth rate between normal and BS cells with both high and normal SCE which originated from the same blood sample strongly indicates that BS DNA chain growth is basically normal and is independent of the SCE character.
