Kunes S, Steller H
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
Genes Dev. 1991 Jun;5(6):970-83. doi: 10.1101/gad.5.6.970.
We have used toxin-mediated ablation to study some aspects of visual system development in Drosophila melanogaster. To devise a method that permits the conditional expression of a cellular toxin, we introduced an amber mutation into the diphtheria toxin-A-chain gene. In transgenic animals, this toxin gene can be activated by providing the gene for an amber suppressor tRNA. By coupling this toxin gene to the photoreceptor cell-specific promoter of the chaoptic gene, photoreceptor cells could be specifically ablated during development. Photoreceptor cell-specific markers normally activated during pupal development failed to appear after midpupation. Photoreceptor cells were absent from the retinas of adult flies at eclosion. We have assessed the consequences of photoreceptor cell ablation for eye and optic lobe development. We suggest that the larval photoreceptor nerve is not essential, in the late larval stages, for retinula photoreceptor cell axons to achieve their proper projection pattern in the brain. Moreover, while retinula photoreceptor innervation is initially required for the development of normal optic ganglia, the ablation of these cells in midpupation has no discernible effect. This approach to cell-specific ablation should be generally applicable to the study of cellular functions in development and behavior.
我们利用毒素介导的细胞消融技术来研究黑腹果蝇视觉系统发育的某些方面。为了设计一种能够实现细胞毒素条件性表达的方法，我们在白喉毒素A链基因中引入了一个琥珀突变。在转基因动物中，通过提供琥珀抑制tRNA基因，可以激活该毒素基因。通过将此毒素基因与chaoptic基因的光感受器细胞特异性启动子相偶联，在发育过程中可以特异性地消融光感受器细胞。在化蛹中期之后，蛹发育期间正常激活的光感受器细胞特异性标记物未能出现。羽化时，成年果蝇的视网膜中没有光感受器细胞。我们已经评估了光感受器细胞消融对眼睛和视叶发育的影响。我们认为，在幼虫后期，幼虫光感受器神经对于视小网膜光感受器细胞轴突在脑中形成正确的投射模式并非必不可少。此外，虽然正常视神经节的发育最初需要视小网膜光感受器的支配，但在化蛹中期消融这些细胞并没有明显的影响。这种细胞特异性消融方法应普遍适用于发育和行为中细胞功能的研究。
