Hedgehog acts by distinct gradient and signal relay mechanisms to organise cell type and cell polarity in the Drosophila abdomen

摘要: The epidermis of the adult Drosophila abdomen is formed by a chain anterior (A) and posterior (P) compartments, each segment comprising one A P compartment. In accompanying paper (Struhl et al., 1997), we provide evidence that Hedgehog protein (Hh), being secreted from compartment cells, organises pattern polarity cells. Here test whether Hh acts directly or signal relay mechanism. We use mutations in Protein Kinase (PKA) smoothened (smo) to activate block transduction clones For cell type, scalar property, both manipulations cause strictly autonomous transformations: cells affected are exactly those only mutant. Hence, infer on specify various types cuticular structures they differentiate. By contrast, these same non-autonomous effects polarity, vectorial property. Consequently, surmise influences indirectly, possibly inducing other signalling factors. Finally, present does not polarise abdominal utilising either Decapentaplegic (Dpp) Wingless (Wg), two morphogens through which during limb development. conclude that, abdomen, type reflect distinct outputs propose controlled separable gradient mechanisms.