Figure 7: Gene expression in limb element growth cartilage in response to development and immobilisation.
From: Limb proportions show developmental plasticity in response to embryo movement
Analysis of changes in gene expression from E12/13 to E15 in both femur and TBT identified a robust expression of skeletal muscle genes at E12/13 followed by a strong down-regulation. Up-stream analysis of these genes identified that this included inhibition of MEF2c (p < 1E-10) (a) Plotting the 17 ‘myogenic’ genes directly associated with MEF2c finding, we noted these were further down-regulated during immobilisation in both the femur and TBT at E15 (plotting all muscle genes would have yielded a similar pattern). (b) Analysis of gene expression differences between DMB treated E15 femur and DMB treated E15 TBT (SAMR analysis) revealed that genes regulated by greater Wnt3a activity (Z = 2.1, p < 1E-10) and greater CTNNB1 (Z = 2.1, p < 1E-9) activity, were expressed at a greater level in the femur than TBT. Genes expressed at a higher level in DMB treated E15 femur are shown in red and lower-level are shown in blue. (c) The genes down-stream of Wnt3a are plotted using data from femur and TBT in growth cartilage from control and immobilised (DMB treated) chicks. Horizontal black lines indicate mean expression values for each gene.
