spontaneous mutations meaning in English

自发突变：不用化学活物理诱变剂而引起的突变。

" the older the mother , the more likely she has acquired spontaneous mutations in [ her chromosomes ] , " and will transmit them at conception , wigler said
母亲的年纪越大，比较可能得到染色体上的自发性突变，然后经由受孕转移给下一代。
In our laboratory , a unique mutation detection system using a shuttle vector plasmid has been established to demonstrate that a low concentration of mnng ( 0 . 2 m ) can induce nontargeted mutation in mammalian cells : the mammalian cells were exposed to 0 . 2m mnng for 2 . 5h , then a shuttle plasmid pz189 carrying supf trna gene was transfected into cells after 24h culture . we found a 5 - fold higher mutation frequency of the plasmid replicated in pretreated cells than the spontaneous mutation frequency of the plasmid replicated in control cells . this kind of mutation did not occur immediately after mnng exposure
我们实验室曾用一特殊的突变检测系统，直接证明dna损伤剂可在哺乳动物细胞诱发非定标性突变：首先用低浓度( 0 . 2 m )的短寿烷化剂mnng (半寿期为1 . 1hr )处理细胞2 . 5h后，继续培养24h ，将重组有用作突变检测的靶基因supftrna基因的穿梭质粒pz189转入细胞复制，发现在未受致癌物直接攻击的穿梭质粒中有较自发突变率高5倍以上的靶基因突变。