To prepare the wild type mbl in prokaryotic system , a pair of primers was designed and synthesized , and was used to amplify mbl gene from the recombinant vector pgem - mbl that contans wild type mbl cdna . a recombinant prokaryotic expression vector , pet28 - mbl , was constructed by inserted the mbl gene into plasmid pet28 ( b ) , and after transfected it into ecoli bl21 ( de3 ) and induced with iptg , recombinant mbl protein was expressed successfully 本实验另选用了原核表达质粒pet28 ( b ) ，根据已构建好的含有mbl野生型基因的t载体pgem - mbl ，设计一对引物， pcr扩增mbl基因，凝胶回收，双酶切pcr产物和pet28 ( b )质粒， t4连接酶连接，转化大肠杆菌dhsa ，氨芋选择培养挑取克隆鉴定。
3 . northern analysis revealed the expression of sod2 mrna in t3 plants of several non - segregation transgenic lines while no signal was shown in wild type plants . several samples of transformants were self pollinated , and progenies from transformed and non - transformed plants ( controls ) were evaluated for salt tolerance Northern分析表明转基因植株均有杂交信号，野生型植株无明显信号，进一步说明sod2基因整合到拟南芥的基因组后已正常转录表达，由信号的强弱来看，表达量有明显的不同，可能与整合的外源基因的拷贝数相关。
This unusual modification causes wild type s . lividans 1326 dna sensitive to site - specific oxidative double - strand cleavage ( dnd phenotype ) . preliminary study revealed that such dna modification involves incorporation of sulphur . the entire functional dnd cluster , 8 . 3kb in size , including 3 orfs - dnda , dndb and dndc was involved in this dna modification 野生型变铅青链霉菌具有一种不同于甲基化修饰的新型dna硫修饰系统，使dna在电泳时易遭到氧化双链切割而导致降解( dnd , dnadegradation )表型( zhouetal . , 1988 , 1994 , 1999 ) 。
Wild arabidopsis thaliana seeds were mutagenized with y - ray , and m2 populations were screened in the medium containing 200mmol / l nacl . 352 potential high - salt - tolerance mutants were selected from 80 , 000 m2 seedlings , and 4 of this m2 mutants showed high - salt - tolerance in their m3 generation . this high - salt - tolerance mutants were backcrossed with the wild type arabidopsis thaliana 在含200mmol lnacl的改良ms培养基上，通过对约80 , 000株m _ 2代幼苗的筛选，共获得352株根仍表现向地性生长或真叶不变为褐色的植株作为可能的突变体。
In this work , the transgenic plants showed a tendency to accumulate less na + and more k + under saline condition than wild type plants and there was a high cytosolic k + / na + ratio in the roots of transgenic lines . 5 . x - ray microanalysis of na + , k + contents of the symplast and apoplast showed that transgenic lines accumulate less na + and more k + in the symplast than wild type plants 在对转基因植株及野生型植株用100nunol lnaci处理六天后， na ” 、 k ”的x一射线微区分析，转基因植株根、叶中质外体na 、 k十含量变化不大，但共质体中na十含量明显降低，广含量高于对照。
