21-P005 The role of a novel Sonic hedgehog target gene in the formation of motor neurons during zebrafish embryonic development

trough FGFR1 at the MHB may regulate cell adhesion properties. Cell adhesion molecule, PB-cadherin (PB-cad), was found to be down-regulated in MHB in the Fgfr1 mutants. PB-cad is expressed in forebrain, midbrain–hindbrain boundary and limb buds [Kitijama et. al., 1999. Developmental Dynamics 215, 206–214] and promote survival of gonocytes in neonatal rats [Wu et al., 2005. Developmental Biology 284, 437–450]. However, in nervous system function of PB-cad remains mainly unknown. Our experiments suggest that PB-cad exists in a specific boundary cell population together with cell cycle inhibitor p21 at E8.5 onwards. To get better understanding about function of PB-cad we have generated a conditional mutant allele of PB-cad by transposon technique [Turakainen et al., 2009. PLoS ONE 4, e4341]. The characterization of phenotype might reveal molecular mechanisms regulating cellular contacts at the midbrain–hindbrain boundary.