Maturation of nascent DNA fragment is disturbed after treatment of cultured mouse FM3A cells with 8-methoxypsoralen plus near-ultraviolet radiation |
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Authors: | Masao Hyodo Taizi Hori Seiitsu Kanno Toshiaki Zanma Kenshi Suzuki |
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Affiliation: | 1. Department of Molecular Biology, Tokai University School of Medicine, Boseidai, Isehara-shi, Kanagawa-ken, 259-11 Japan;2. Biological Science Laboratory, Lion Corporation, Tajima, Odawara-shi, Kanagawa-ken, 250 Japan |
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Abstract: | By the method of sedimentation in 5–20% alkaline sucrose gradient, the process of maturation of the nascent DNA fragment was studied with cultured mouse FM3A cells treated with 8-methoxypsoralen plus near-ultraviolet radiation. This treatment is known to cause crosslinks of the chromosomal DNA strands. The profile of the newly-replicated DNA, labeled for 10 min with [3H]thymidine immediately after treatment, was the same as that of the untreated cells, where the incorporated radioactivity was present in the intermediate DNA fragment (about 50–80 S). But, when the treated cells were labeled after several hours of incubation, the labeled DNA became much shorter due to inhibition of maturation of the initial DNA fragment (the Okazaki fragment) to the intermediate DNA. With the use of aphidicolin, a specific inhibitor of eukaryotic DNA polymerase α, it became apparent that, in addition to formation of the crosslinks, further DNA replication is required to cause this inhibition of DNA maturation. Aphidicolin also suppressed the inhibition of incorporation of [3H]thymidine into cellular DNA after treatment, but inhibition of this incorporation resumed after its removal. |
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Keywords: | DNA maturation 8-Methoxypsoralen Ultraviolet irradiation (Mouse cell) |
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