Simmonds A, Hughes S, Tse J, Cocquyt S, Bell J
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Mech Dev. 1997 Sep;67(1):17-33. doi: 10.1016/s0925-4773(97)00096-8.
The vestigial gene product is required for the completion of wing development in Drosophila melanogaster. In the absence of vestigial gene expression, cells within the larval wing and haltere imaginal discs fail to proliferate normally thus producing adults with severely reduced wings. Of a large number of vestigial mutations that have been characterized, only two are currently known to exist, vestigial(U) and vestigial(W), which manifest a significant dominant phenotype. Both are associated with chromosomal inversions that fuse the majority of the vestigial coding regions to other genes; mastermind in vestigial(U) and invected in vestigial(W) Examination of vestigial expression in the presence of these dominant alleles shows alterations in the disc-specific expression of vestigial during later stages of larval development. These patterning disruptions are specific to cells of the wing imaginal disc, as significant suppression of total levels of vestigial expression within entire larvae could not be detected. This dominant interference of vestigial patterning appears to be mediated in part by the vestigial coding sequences that are within the gene fusions. Further evidence that the dominant phenotype is the result of disrupted vestigial patterning comes from observations that the dominant alleles can be partially suppressed by mutations within the Drosophila-epidermal growth factor receptor gene. Mutagenesis of vestigial(U) and vestigial(W) produced a series of alleles with partially dominant phenotypes that restored various amounts of the adult wing. These phenotypes can be correlated with alterations in specific portions of the vestigial sequences associated with the dominant alleles. In the presence of these partially dominant alleles, wing imaginal discs have significantly more cells which express vestigial compared with the number associated with the original dominant phenotype. Additionally, eliminating some of the dominant effect causes alterations in the patterns of early stage apoptotic cell death associated with dominant vestigial alleles. Utilizing these new vestigial alleles, it is possible to correlate the consequence of altered vestigial expression to subsequent changes in patterning of the wing disc.
残翅基因产物是黑腹果蝇翅发育完成所必需的。在没有残翅基因表达的情况下，幼虫翅和平衡棒成虫盘内的细胞无法正常增殖，从而产生翅严重退化的成虫。在已鉴定的大量残翅突变中，目前已知仅存在两种，即残翅（U）和残翅（W），它们表现出显著的显性表型。两者都与染色体倒位有关，这些倒位将大部分残翅编码区域与其他基因融合；在残翅（U）中与主谋基因融合，在残翅（W）中与内卷基因融合。在这些显性等位基因存在的情况下对残翅表达的检测表明，在幼虫发育后期，残翅在盘特异性表达上发生了改变。这些模式破坏是翅成虫盘细胞特有的，因为在整个幼虫中未检测到残翅表达总水平的显著抑制。残翅模式的这种显性干扰似乎部分是由基因融合中的残翅编码序列介导的。显性表型是残翅模式破坏的结果的进一步证据来自于这样的观察，即显性等位基因可以被果蝇表皮生长因子受体基因内的突变部分抑制。残翅（U）和残翅（W）的诱变产生了一系列具有部分显性表型的等位基因，这些等位基因恢复了不同程度的成虫翅。这些表型可以与与显性等位基因相关的残翅序列特定部分的改变相关联。在这些部分显性等位基因存在的情况下，翅成虫盘表达残翅的细胞比与原始显性表型相关的细胞数量显著更多。此外，消除一些显性效应会导致与显性残翅等位基因相关的早期凋亡细胞死亡模式发生改变。利用这些新的残翅等位基因，可以将残翅表达改变的后果与翅盘模式的后续变化联系起来。
