Skeletal Muscle Neural Precursor Figure 2. Nestin-GFP+ cells attached to myofiber (satellite cells) do not produce Tuj1+ cells with a neural phenotype. A. A representative EDL muscle cross-section from a nestin-GFP transgenic mouse showing GFP expression and Pax7+ immunoreaction (n = 3 mice, 6 EDL muscles). Myofibers were counterstained with Hoechst. The merge image shows examples of GFP+/Pax- cells (arrows). Scale bar = 50 mm. B. Enzymatically dissociated single FDB muscle fiber showing 2 nestin-GFP+ satellite cells that immunoreact to Pax7 and overlap with Hoechst nuclear staining. Scale bar = 100 mm. C. FDB satellite cell time-lapse analysis. A nestin-GFP+ satellite cell attached to an FDB fiber (arrow) analyzed for more than 6 days. Snapshots of the complete record at 4, 50, 80, 154, and 162 h. Brightfield (a, c, e, g, h) and fluorescence (b, d, f). Fluorescence completely disappeared at 162 h in culture. Scale bar = 50 mm. Da. Four-month satellite cell culture from isolated EDL fibers. Myoblasts and myotubes are stained for desmin and Hoechst, which overlap with the brightfield image. b. The culture shown in Da is MyoD+ but Tuj1-. Scale bar for all pictures in D = 100 mm. doi:10.1371/journal.pone.0016816.g002 Figure 4B shows another response in a neural cell exposed to glutamate for 1 s; desensitization during the exposure is apparent. Unfortunately, these experiments did not last long enough to test currents in response to glutamate pulses at more than 2–3 membrane potentials, so channel conductance could not be calculated. An outward current at positive membrane potentials PLoS ONE | www.plosone.org 6 February 2011 | Volume 6 | Issue 2 | e16816