Fig. 7. Effect of a dominant-negative form of Barhl2 on the formation of different retinal cell types. (A) Schematic of control-GFP and Barhl2-EnR-GFP retroviral constructs. (B) Percentages of virus-transduced cells located in different cellular layers of the retina (means±s.d.). More than 500 GFP⁺ cells in three or four independent retinas were scored for either control-GFP or Barhl2-EnR-GFP virus. (C) Percentages of virus-transduced cells that became immunoreactive for a series of cell type-specific markers. Each histogram represents the mean±s.d. for three to five retinas. More than 500 GFP⁺ cells were scored in each retina. (D,E) Virus-transduced GFP⁺ cells were visualized in P30 retinal sections that were weakly counterstained with DAPI. Infection with Barhl2-EnR-GFP viruses resulted in a significant decrease of INL cells. (F-K) Sections from P30 retinas infected with control-GFP or Barhl2-EnR-GFP viruses were double-immunostained with an anti-GFP antibody and antibodies against Pax6 (F,G), GLYT1 (H,I) or GABA (J,K). All sections were weakly counterstained with DAPI. Forced Barhl2-EnR expression reduced the number of amacrine cells immunoreactive for Pax6 (F,G) and GLYT1 (H,I) but had no effect on amacrine cells immunoreactive for GABA (J,K). Arrows indicate representative colocalized cells. EnR, engrailed repressor domain; GCL, ganglion cell layer; GS, glutamine synthase; INL, inner nuclear layer; IPL, inner plexiform layer; ONL, outer nuclear layer; OPL, outer plexiform layer. Scale bar: 25 µm.