Lardelli M, Ish-Horowicz D
Zoology Department, University of Oxford, England.
Development. 1993 May;118(1):255-66. doi: 10.1242/dev.118.1.255.
The hairy (h) segmentation gene of Drosophila regulates segmental patterning of the early embryo, and is expressed in a set of anteroposterior stripes during the blastoderm stage. We have used a set of h gene deletions to study the h promoter and the developmental requirements for individual h stripes. The results confirm upstream regulation of h striping but indicate that expression in the anterodorsal head domain depends on sequences downstream of the two transcription initiation sites. Surprisingly, the two anterior-most h domains appear to be dispensable for head development and embryonic viability. One partial promoter deletion expresses ectopic h, leading to misexpression of other segmentation genes and embryonic pattern defects. We demonstrate that h affects patterning outside its apparent stripe domains, supporting a model in which primary pair-rule genes act as concentration-dependent transcriptional regulators, i.e. as local morphogens.
果蝇的毛状（h）分割基因调控早期胚胎的节段模式形成，并在囊胚期以一组前后条纹的形式表达。我们利用一组h基因缺失来研究h启动子以及各个h条纹的发育需求。结果证实了h条纹形成的上游调控，但表明前背头部区域的表达依赖于两个转录起始位点下游的序列。令人惊讶的是，最前面的两个h区域对于头部发育和胚胎存活似乎是可有可无的。一个部分启动子缺失会表达异位h，导致其他分割基因的错误表达和胚胎模式缺陷。我们证明h在其明显的条纹区域之外影响模式形成，支持了一个模型，即初级成对规则基因作为浓度依赖性转录调节因子，也就是作为局部形态发生素起作用。
