Figure 7.
Decreased GFAP levels in cochlear nucleus astrocytes in strongly affected SefKST223mutants. a, a', A coronal section through DCN from a P14 SefKST223 heterozygote double labeled for β-galactosidase activity (a) and antibodies to GFAP (a'). Sef-β-geo and GFAP have similar patterns of distribution, with intense expression in the molecular layer (arrows). b, Double labeling of a P17 SefKST223heterozygote with antibodies to TuJ1 (green) and β-galactosidase (β-gal; red) shows production of Sef-β-geo in small non-neuronal cells (arrows) in the molecular layer. c, c', Merged (c) and single channel (c') Z series projections of two astrocytes (arrows). Sef-β-geo (red) is present in a puncate pattern within the cytoplasm of GFAP-positive astrocytes (green). β-gal, β-Galactosidase. d–g, Anti-GFAP antibody labeling of coronal sections from a wild type (d, f) and a SefKST223 homozygote (e, g) through AVCN at the entry of the eighth nerve (8th n.). Dorsal (D) is up and to the left; lateral (L) is up and to the right. The dashed line indicates the boundary between the cochlear nucleus and the rest of the brainstem. The sections were processed and analyzed in parallel, using the same settings for image capture. High-power views of the granule cell layer are shown in f and g and correspond to the region boxed in d. In normal animals, GFAP staining is prominent in the microneuronal shell (arrows) and in the eighth nerve. Although GFAP continues to be expressed at high levels on the surface of the cochlear nucleus and in scattered cells (g, arrows), very little expression is seen in the microneuronal shell of a SefKST223 homozygote that had significantly elevated ABR thresholds in both ears (55 dB on the right and 80 dB on the left for wave iii). cb, Cerebellum. Scale bars: a, b, d, 40 μm; c, 5 μm; f, 10 μm.