Fig. 1

Immunofluorescence (A–D) and immunohistochemistry (E–H) targeting glial fibrillary acidic protein (GFAP, green) and glutamine synthetase (GS) in Müller cells (MCs) in 4- and 7-month-old wild type (WT) and Glb1 knockout (Glb1^−/−) mice. WT mice show weak GFAP positive signals only within uppermost retinal layers at both time points investigated, most likely in the endfeet of MCs and perivascular astrocytes (A, C). Within 4 and 7-month-old Glb1^−/− mice, strong GFAP positive signals can be detected also labeling the cell bodies of MCs, extending into deeper retinal layers (B, D). Nuclei are counterstained with bisbenzimide (blue). 4 and 7-month-old WT and Glb1^−/− mice show high numbers of MCs immunopositive for the MC specific marker GS. Quantification of GS positive MCs reveals an increase of GS positive cells in Glb1^−/− mice at 4 months of age (F) compared to WT animals (E). No difference was detected between WT and Glb1^−/− mice in 7-month-old animals (H), probably due to downregulation of GS in MCs as result of progressive neuronal loss. Scale bars: 20 μm. Statistical analysis of GFAP and GS expression in retinal MCs (I,J). Graphs display box and whisker plots. Significant differences between groups were detected by Kruskal-Wallis test followed by Dunn’s-Bonferroni procedure; *p ≤ 0.05; n = 5. GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer.