title: The role of the anterior neural ridge and Fgf-8 in early forebrain patterning and regionalization in Xenopus laevis.
abstract: The tissue, cellular and molecular mechanisms that regulate early regional specification of the vertebrate forebrain are largely unknown. We studied the expression patterns of Xbf-1, an anterior (and telencephalon) neural-specific winged helix transcription factor and Fgf-8, an early-secreted factor. This study looked at Xbf-1 and Fgf-8 expression in combination with embryonic grafting experiments and also used beads containing the recombinant Fgf-8 protein to determine these factors' effects upon forebrain patterning events. We provide evidence that additional Fgf-8 displaces Xbf-1 expression posteriorly, suggesting a concentration dependence of Fgf-8 for the early distinct regionalization of the telencephalic primordia. Also, additional stage 15 mid-anterior neural ridge (mANR) transplants inhibited telencephalon development, whereas lateral ANR transplants facilitated increased areas of telencephalon development. In both cases, these transplantations promoted ectopic expression of Xbf-1. These studies suggested that the distinct regionalization of the forebrain primordia involves the inhibitory actions of the mANR towards a telencephalon development and maintaining bilateral telencephali. These telencephalic primordia are initially localized by optimal Fgf-8 expression. The anterior mANR will eventually become the anterior and rostral diencephalic tissue. This in vivo study demonstrated Fgf-8 and the mANR are important in forebrain regionalization.
authors: Department of Biology, Loras College, Dubuque, Iowa 52004-0178, USA. eaglegw@loras.edu
authors: Gerald W
authors: GW
authors: Eagleson
authors: Ryan D
authors: RD
authors: Dempewolf
mesh_terms: D000818:Animals; D019521:Body Patterning; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000096:biosynthesis* / Q000502:physiology*; D017403:In Situ Hybridization; D009432:Neural Crest / Q000196:embryology*; D009474:Neurons / Q000378:metabolism; D016548:Prosencephalon / Q000196:embryology*; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000096:biosynthesis; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: C117087:FOXG1 protein, Xenopus; D012333:RNA, Messenger; D014157:Transcription Factors; D029867:Xenopus Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors