A Digital Atlas to Characterize the Mouse Brain Transcriptome
Figure 4
Quantitative Analysis of Rorb and Grm2 Expression in Control and brl P7 Brains
(A) The dataset of 200 genes was searched using a query pattern defined as strong expression in layer IV of the somatosensory cortex (SsCx) (red) and no expression in layers I and II/III somatosensory cortex (grey) for standard section 2. Rorb and Grm2 were two of the top matches returned.
(B) The strong expression Rorb in control somatosensory cortex layer IV coincides with the anatomical shape of the barrels that are absent in the brl mouse. For both genotypes, cellular expression was detected and color-coded by signal strength using the Celldetekt software, followed by fitting of the appropriate subdivision mesh to the shape of the cortex. A row of 12 quadrilaterals in the subdivision mesh defines the area of comparison in the somatosensory cortex layer IV. Note the greater prevalence of strongly expressing cells (red) in the control tissue. Moderately expressing cells and weakly expressing cells are indicated by blue and yellow, respectively.
(C) Quantification of Grm2 expression in somatosensory cortex layer IV as described for Rorb showed no difference in expression strength distribution between control and brl.
(D) Statistical comparisons between control and brl revealed no significant changes in the percentage of somatosensory cortex layer IV cells expressing either Rorb (p = 0.8) or Grm2 (p = 0.5). However, a significant decrease in the percentage of strongly expressing cells was found for Rorb in brl (p = 0.02), but not for Grm2 (p = 0.8).
(E) The somatosensory cortex containing the barrel region was dissected as indicated (highlighted and boxed) and used for quantitative real-time PCR analysis.
(F) Consistent with the ISH data, a statistically significant decrease in Rorb expression was found in brl by quantitative real-time PCR (p = 0.008).