Zachar Z, Bingham P M
Cell. 1982 Sep;30(2):529-41. doi: 10.1016/0092-8674(82)90250-1.
We have analyzed the structures of 19 mutant alleles at the white locus of Drosophila melanogaster. Thirteen of the mutant alleles in our selected sample arose spontaneously, and of these, seven are associated with insertions of non-white-region DNA sequence elements. Several lines of evidence strongly suggest that these insertions are responsible for their associated mutant alleles, and further suggest that most or all of these insertions are transposons. Moreover, the white locus DNA sequences can be divided into two nonoverlapping domains on the basis of the properties of the two domains as mutational targets. One of these domains behaves, in this regard, in the manner expected of functional coding sequences, whereas the other does not. We propose a model for the nature and function of the presumptive noncoding white locus genetic elements. The two domains of the white locus defined by our studies are approximately coextensive with the functionally distinct subintervals of the locus defined by previous genetic analysis. Lastly, our results strongly suggest that the dominant, mutable wDZL allele results from the insertion of a transposon outside of, but near, the white locus. This putative transposon apparently carries genetic elements that act at a distance to repress expression of the white locus.
我们分析了黑腹果蝇白色基因座上19个突变等位基因的结构。在我们所选样本中的13个突变等位基因是自发产生的，其中7个与非白色区域DNA序列元件的插入有关。几条证据有力地表明，这些插入导致了与其相关的突变等位基因，并且进一步表明这些插入中的大多数或全部都是转座子。此外，根据两个结构域作为突变靶点的特性，白色基因座DNA序列可分为两个不重叠的结构域。在这方面，其中一个结构域的行为符合功能编码序列的预期方式，而另一个则不然。我们提出了一个关于假定的非编码白色基因座遗传元件的性质和功能的模型。我们的研究所定义的白色基因座的两个结构域与先前遗传分析所定义的该基因座功能上不同的子区间大致相同。最后，我们的结果有力地表明，显性的、可变的wDZL等位基因是由一个转座子插入到白色基因座之外但靠近它的位置所导致的。这个假定的转座子显然携带了能在远距离起作用以抑制白色基因座表达的遗传元件。
