کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4357065 | 1300028 | 2013 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: The type of mutations induced by carbon-ion-beam irradiation of the filamentous fungus Neurospora crassa The type of mutations induced by carbon-ion-beam irradiation of the filamentous fungus Neurospora crassa](/preview/png/4357065.png)
Heavy-ion beams are known to cause great damage to cellular components and are particularly renowned for their ability to generate DNA double-strand breaks (DSBs). To gain insight into the mutagenic effect of carbon-ion beams and how such damage is repaired by the cell, Neurospora crassa mutants deficient in one of three components involved in the repair of DSBs, nonhomologous end-joining (NHEJ), homologous recombination repair (HR), and the Mre11-Rad50-Xrs2 (MRX) complex, were irradiated with a carbon-ion beam and killing effect, mutation frequencies, and the type of mutation incurred by survivors were analysed. The sensitivity of the NHEJ-deficient strain (mus-52) was higher than that of the wild-type and the HR-deficient (mei-3) strains at low doses of radiation, but was little changed as the level increased. As a result both the wild-type and HR-deficient strains were more sensitive than the NHEJ-deficient strain at high radiation levels. In addition, the frequency of forward mutation at the adenine-3 (ad-3) loci of the NHEJ-deficient mutant was lower than that of the wild-type strain at all levels, while the mutation frequency of the HR-deficient strain was consistently ∼3-fold higher than the wild-type. From the comparison of mutation type of each strain, deletions were frequently observed in wild-type strain, whilst base substitution and deletion in the mus-52 and mei-3 strains. These mutations resulting from carbon-ion-beam irradiation depend on the mechanism invoked to cope with DSBs. Furthermore, in wild-type cells, these mechanisms likely compete to repair DSBs.
► The mus-52 strain (ΔNHEJ) showed resistance to C-ion-beam irradiation at over 100 Gy.
► C-ion-beam-induced mutation frequencies were ΔNHEJ < WT < ΔHR strains.
► Multiple mutations were also observed in WT and mei-3 (ΔHR) strains.
► Putative difference of mutagenesis between S. cerevisiae and N. crassa was discussed.
Journal: Fungal Biology - Volume 117, Issue 4, April 2013, Pages 227–238