不同启动子控制下Ac转座酶基因的表达对玉米Ds因子在水稻中切离频率的影响

用水稻愈伤组织比较了Ac启动子、35S启动子与Ubi启动子控制下Ac转座酶基因（Ts）的表达对Ds因子切离频率的影响。结果表明Ubi启动子与Ac转座酶编码区嵌合基因（Ubipro-Ts）反式激活Ds因子的切离频率最高,达到了72.9%。通过杂交将Ubipro-Ts基因导入Ds因子转化植株,得到9株Ubipro-Ts基因与Ds因子共存的F1代杂交水稻植株,其中有8株Ds因子发生了切离。用Inverse-PCR的方法从其中一株杂交植株中克隆到Ds因子的旁邻序列,其DNA顺序与亲本中Ds因子原插入位点的序列不同,表明Ds因子转座到了新的基因组位点。     

Depression of the xylanase-encoding cgxA gene of Chaetomium gracile in Aspergillus nidulans

Regulation of the Chaetomium gracile xylanase A gene (cgxA) was investigated using Aspergillus nidulans as an intermediate host. Deletion of a 185 bp DNA fragment from its promoter region led to higher levels of the cgxA gene expression, indicating that the 185 bp DNA fragment contains an element involved in repression of the gene. A nuclear extract was assayed for proteins which bind to the 185 bp DNA fragment. A protein designated AnRP bound sequence specifically to the DNA fragment. The minimum sequence required for AnRP binding, 5'TTGACAAAT-3', was determined by means of gel mobility shift assays with various double-stranded oligonucleotides. Furthermore, this sequence repressed the expression of the cgxA gene when inserted at the 5' end of the cgxA gene on pXAH, which was deleted for the repressive element from the promoter region.