Fig. 1

Apoptosis is essential for precise spinal cord and muscle patterning.a Schematic illustration of the expression patterns of dbx1b (a p0 neural progenitor marker), olig2 (a pMN neural progenitor marker), and foxa2 (a floor plate progenitor marker) in the spinal cord. b Inhibiting apoptosis distorts dorso-ventral (DV) patterning in the spinal cord. The panels show whole-mount in situ hybridisation of dbx1b, olig2, and foxa2 in wild-type (uninjected), injected control (GFP mRNA-injected) and apoptosis-inhibited (bcl2a mRNA-injected) 24 h post-fertilisation (hpf) larvae. In abnormal larvae, dbx1b, olig2, and foxa2 were ectopically activated or inactivated in discontinuous regions. The bottom graph shows the percentages of larvae with normal or abnormal expression patterns in uninjected, GFP mRNA- or bcl2a mRNA-injected (apoptosis-inhibited) larvae. Scale bar = 100 ?m. The chi-square test was used for statistical analysis. c Schematic illustration of muscle cell pattern. The labels (1) and (2) in (d?f) correspond to the images of sections indicated as (1) and (2) in (c). d?f Apoptosis inhibition distorts gene expression patterns in the muscle primordia. The panels show whole-mount immunostaining for fast myosin (F310, fast muscle cells) (d), slow myosin (F59, slow muscle cells) (e), and muscle pioneer (4D9, muscle pioneer cells) (f), respectively (magenta). In abnormal larvae, fast myosin, slow myosin, and muscle pioneer proteins are ectopically expressed or are absent. Scale bar = 100 ?m. Bar plots on the right show the mean + SEM of abnormal gene expressing-cell numbers in wild-type (uninjected) and apoptosis-inhibited (bcl2a mRNA-injected) larvae. An unpaired two-tailed t-test was used for the statistical analysis. Source data are provided as a Source Data file.