Figure 5

Specific reporter gene activation is maintained in kidney organ culture supplemented with BMP4. A – C. Strong reporter gene activation can be seen in collecting ducts of kidneys cultured for 48 hours in serum free medium with or without addition of BMP4, whereas the nephrogenic mesenchyme is devoid of reporter activation. A', B'. In untreated cultures, or cultures treated with a low dose of BMP4, reporter gene activation is limited to the collecting duct trunk. C'. At high dose of BMP4 treatment, the reporter is ectopically activated in collecting ducts tips. D. To control for the possibility that the transgene is inactivate specifically in the nephrogenic mesenchyme, transgene expression was activated by 120 minutes heat shock at 42°C. Strong expression of the transgene is seen throughout the organ. D'. Heat shocked wild type kidney explant demonstrating absence of background staining. Abbreviations: CD: collecting duct, NM: nephrogenic mesenchyme, Ti: collecting duct tip, Tr: collecting duct trunk.