title: Alkylating agent (MNU)-induced mutation in space environment.
abstract: In recent years, some contradictory data about the effects of microgravity on radiation-induced biological responses in space experiments have been reported. We prepared a damaged template DNA produced with an alkylating agent (N-methyl-N-nitroso urea; MNU) to measure incorrect base-incorporation during DNA replication in microgravity. We examined whether mutation frequency is affected by microgravity during DNA replication for a DNA template damaged by an alkylating agent. Using an in vitro enzymatic reaction system, DNA synthesis by Taq polymerase or polymerase III was done during a US space shuttle mission (Discovery, STS-91). After the flight, DNA replication and mutation frequencies were measured. We found that there was almost no effect of microgravity on DNA replication and mutation frequency. It is suggested that microgravity might not affect at the stage of substrate incorporation in induced-mutation frequency.
authors.affiliation: Department of Biology, Nara Medical University, Kashihara, Japan. tohnishi@naramed-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Ohnishi
authors.forename: A
authors.initials: A
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Ohnishi
authors.forename: S
authors.initials: S
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Masukawa
authors.forename: K
authors.initials: K
authors.lastname: Sekikawa
authors.forename: T
authors.initials: T
authors.lastname: Amano
authors.forename: T
authors.initials: T
authors.lastname: Nakano
authors.forename: S
authors.initials: S
authors.lastname: Nagaoka
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000187:drug effects; D004867:Equipment Design; D004926:Escherichia coli / Q000235:genetics; D008770:Methylnitrosourea / Q000494:pharmacology*; D009154:Mutation; D010957:Plasmids; D012269:Ribosomal Proteins / Q000235:genetics; D013026:Space Flight / Q000295:instrumentation*; D019914:Taq Polymerase; D013698:Templates, Genetic; D014893:Weightlessness
chemical_list: D000477:Alkylating Agents; D004269:DNA, Bacterial; D012269:Ribosomal Proteins; C034212:ribosomal protein S12; D008770:Methylnitrosourea; D019914:Taq Polymerase