Larsen E, Lee T, Glickman N
Department of Zoology, University of Toronto, Ontario, Canada.
Dev Genet. 1996;19(4):333-9. doi: 10.1002/(SICI)1520-6408(1996)19:4<333::AID-DVG6>3.0.CO;2-A.
We explore the transformation of antenna to leg in Drosophila melanogaster, using ectopically expressed transgenes with heat shock promoters: heat shock Antennapedia, heat shock Ultrabithorax, and heat shock mouse Hox A5. We determined the frequency of transformation of several leg markers in response to Antennapedia protein delivered by heat shock at different times and doses. We also studied stage-specific responses to the transgene, heat shock mouse Hox A5. Results show that each marker has its own stage and dose-specific pattern of response. The same marker could pass through a period of high-dose inhibition followed by a dose-independent response and then a positive dose-dependent phase. The heat shock-induced transgenes and spineless aristapedia transformed the apterous enhancer trap antenna disc expression pattern toward the pattern found in leg discs. These results are considered in relation to developmental competence-the ability of developing tissue to respond to internal or external influences. The results suggest that all genes tested interact with the same competence system and that at least two classes of mechanisms are associated with antenna to leg transformation: one comprises global mechanisms that permit transformation over approximately 24 hr; the second class of mechanisms act very locally and are responsible for changes in dose response on the order of 4-8 hr.
我们利用带有热休克启动子的异位表达转基因，即热休克触角足基因、热休克超双胸基因和热休克小鼠Hox A5基因，来探究黑腹果蝇中触角向腿的转变。我们测定了几种腿部标记物在不同时间和剂量的热休克所传递的触角足蛋白作用下的转变频率。我们还研究了对转基因热休克小鼠Hox A5的阶段特异性反应。结果表明，每个标记物都有其自身的阶段和剂量特异性反应模式。同一个标记物可能会经历一个高剂量抑制期，随后是剂量不依赖反应，然后是正剂量依赖期。热休克诱导的转基因和无芒芒状触角基因将无翅增强子陷阱触角盘的表达模式转变为腿部盘状结构中的表达模式。这些结果是结合发育能力来考虑的，发育能力是指发育中的组织对内部或外部影响作出反应的能力。结果表明，所有测试基因都与同一能力系统相互作用，并且至少有两类机制与触角向腿的转变相关：一类包括允许在大约24小时内发生转变的全局机制；第二类机制作用非常局部，负责在4 - 8小时左右的剂量反应变化。
