Upshall A
ZymoGenetics, Inc., Seattle, WA 98103.
Curr Genet. 1986;10(8):593-9. doi: 10.1007/BF00418126.
Thirty-three argB- to argB+ transformants of Aspergillus nidulans have been subjected to genetic and molecular analysis. Two showed high levels of mitotic instability although it is suggested that this is a consequence of heterokaryosis rather than instability of the transformation event. Most transformants resulted from the integration of the transforming DNA in tandem with the chromosomal argB locus. The maximum number of inserted sequences was two, to generate three copies of the argB locus. The other main transformant type showed replacement of the argB- mutation by the wild-type allele present on the transforming plasmid. Transformants were also recovered in which the transforming DNA had integrated into non-homologous chromosomal regions. Selfed or hybrid cleistothetica from all transformants, except the gene replacement types gave arginine requiring recombinants. Most transformants showed low levels of meiotic instability. Others displayed varying levels which in some cases differed between selfed and hybrid cleistotheticia. There was some correlation between meiotic instability and the nature of the transformation event. Diploid parasexual and aneuploid analysis located the integrated DNA in each transformant to chromosome III. Two transformants were isolated as heterozygous diploids. A third diploid was isolated as a stable mitotic segregant from one of the mitotically unstable transformants.
对构巢曲霉的33个从argB - 转变为argB + 的转化体进行了遗传和分子分析。有两个转化体表现出较高水平的有丝分裂不稳定性，不过有人认为这是异核体的结果，而非转化事件的不稳定性。大多数转化体是由于转化DNA与染色体argB基因座串联整合所致。插入序列的最大数量为两个，从而产生了三个拷贝的argB基因座。另一种主要的转化体类型表现为转化质粒上的野生型等位基因取代了argB - 突变。还获得了转化DNA整合到非同源染色体区域的转化体。除基因取代类型外，所有转化体的自交或杂交闭囊壳产生了需要精氨酸的重组体。大多数转化体表现出较低水平的减数分裂不稳定性。其他转化体则表现出不同程度的不稳定性，在某些情况下，自交闭囊壳和杂交闭囊壳之间存在差异。减数分裂不稳定性与转化事件的性质之间存在一定的相关性。二倍体准性生殖和非整倍体分析将每个转化体中的整合DNA定位到了第三条染色体上。分离出了两个作为杂合二倍体的转化体。第三个二倍体是从有丝分裂不稳定的转化体之一中作为稳定的有丝分裂分离子分离出来的。
