Figure 4

RNA expression levels of the Class 3 Semaphorins in the rat superior colliculus during development. Sema3s: All Sema3 RNA expression levels, except for Sema3e, peak at E19 and are lowest by P21 and into the adult. Sema3b, Sema3c and Sema3f are the predominant transcripts with around 100 times higher levels than Sema3a and Sema3e. Sema3a: There is a high variability in expression at E16, peak expression at E19, falling twofold by birth and eightfold in the adult. Sema3b: Expression changes markedly throughout development, with high variability levels at both E19 and P14. Expression rises twenty-eightfold from E16 to E19 before falling back 17 fold by P7 and back to E16 levels at P21. Transcript levels then rise eightfold from P21 to adult. Sema3c: RNA levels peak at E19 and P0, falling twofold by P14 and maintaining that level into the adult. Sema3e: Transcript levels double and triple from the embryo to P7 and P14 respectively, dropping back at P21 and increasing again into the adult. Sema3f: RNA expression levels are highest in the embryo, dropping fivefold after birth and into the adult. Error bars are SEM; * p < 0.05; n = 4–5.