... is normally just initiated ( Fig. 3 Bd). We also find that r5 krox-20 , a val target ( Moens et al., 1996 ) is absent and r3 krox-20 is reduced at 10.3 h/1 s (not shown). To address patterning of rhombomeres further at early stages in fgf3 -MO; fgf8 − embryos, we analyzed expression of the early...

... patterns. The transcription factor gene Krox-20 is restricted to r3 and r5, and is required for the development of these rhombomeres. We present evidence that Krox-20 transcriptional activity is under the control of a negative feedback mechanism in the hindbrain. This regulatory loop involves two closely...

... and the caudal stripe of Krox-20 extends into the presumptive rhombomeres 6 and 7 region. In this region, Hoxb-1 is ectopically expressed, Hoxb-3 is ectopically up-regulated and Hoxd-4 expression is abolished. These data, which indicate that retinoic acid signaling through RARα and/or RARβ is essential...

...Todd S. Zorick; Daniel E. Syroid; Adrienne Brown; Tom Gridley; Greg Lemke The transcription factors Krox-20 and SCIP each play important roles in the differentiation of Schwann cells. However, the genes encoding these two proteins exhibit distinct time courses of expression and yield distinct...

...Françoise Helmbacher; Cristina Pujades; Carole Desmarquet; Monique Frain; Filippo M. Rijli; Pierre Chambon; Patrick Charnay ABSTRACT The transcription factor genes Hoxa1 and Krox-20 have been shown to play important roles in vertebrate hindbrain segmentation. In this report, we present evidence...

... between odd- and even- numbered rhombomeres. We have analysed the cis -acting regulatory sequences of the EphA4 gene in transgenic mice and identified a 470 bp enhancer element that drives specific expression in r3 and r5. Within this element, we have identified eight binding sites for the Krox-20...

... of the hindbrain. Mauthner cell multiplications in the posterior hindbrain, and (both anteriorly and posteriorly) expanded Krox-20 expression domains indicated (partial) transformation of a large part of the hindbrain into (at least partial) rhombomere 3, 4 and/or 5 identity. In contrast, the fore-and midbrain...

... to a recently segmented hindbrain leads to disappearance of posterior rhombomere boundaries. Boundary loss is preceded by changes in segmental expression of Krox-20 and Cek-8 and followed by alterations in Hox gene expression. The characteristic morphology of boundary cells, their expression of follistatin...

...Sylvie Schneider-Maunoury; Tania Seitanidou; Patrick Charnay; Andrew Lumsden ABSTRACT The vertebrate hindbrain is transiently segmented during its early development with the formation of reiterated bulges, the rhombomeres (r). The Krox-20 gene, which encodes a zinc finger transcription factor, has...

...Paula Murphy; Piotr Topilko; Sylvie Schneider-Maunoury; Tania Seitanidou; Annick Baron-Van Evercooren; Patrick Charnay ABSTRACT The zinc finger transcription factor gene Krox-20 is expressed in Schwann cells and is required for the myelination of peripheral nerves. We show that the regulation...

... quail-chick chimaeras fate map Krox-20 c-cadherin7 The mechanisms that guide outgrowing motor axons from their origin in the neuroepithelium into the periphery and then to their final target are only partly understood. Axons of spinal motor neurons of the trunk, for example, grow away...

.... In this paper, we have examined whether inter-rhombomere interactions control further aspects of rhombomere phenotype. We find that the expression of Krox-20 and the repression of follistatin in r3 is dependent upon neighbour interaction, whereas these genes are expressed autonomously in r5. We further...

..., vertebrate homologs of the Drosophila HOM-C homeotic selector genes, are expressed in rhombomere-restricted patterns and are believed to participate in regulating segmental identities. Krox-20 , a zinc finger gene, has a highly conserved pattern of expression in r3 and r5 and is functionally required...

... in the mouse Krox-20 gene, which encodes a zinc finger transcription factor, by in frame insertion of the E. coli lacZ gene and shown that hindbrain segmentation and peripheral nerve myelination are affected in Krox-20 − / − embryos. We report here that Krox-20 is also activated in a subpopulation of growth...

... in the posterior hindbrain corresponds to an altered pattern of gene expression in that region, with major abnormalities posterior to the r4/5 boundary and minor abnormalities anterior to it. From the expression patterns at E9.5 of Krox-20, Hoxb-1 (Hox 2 . 9), Hoxb-2 (Hox 2 . 8), Hoxa-3 (Hox 1 . 5), Hoxd-4 (Hox 4...

...-normal rhombomeric segmentation; rhombomeric gene expression domains indicate that only rhombomere 2 has changed its genetic identity to that of rhombomere 4, the other preotic segments showing normal expression patterns for HoxB genes and Krox-20 . The results indicate that RA has separable effects (1...

... rhombomere-specific genes in mouse embryos homozygous for the kreisler ( kr ) mutation, in which rhombomeres 4-7 are replaced by a smooth morpho-logically unsegmented neural tube. Using molecular probes specific for Hoxb-1 (Hox-2 . 9), Hoxb-3 (Hox-2 . 7), Hoxb-4 (Hox-2 . 6), Krox-20 , or Fgf-3 ( Int-2 ), we...

... on rhombomere morphology and specific effects on the development of the anterior rhombomeres. This effect is demonstrated using neurofilament antibodies, HRP staining and in situ hybridisation using a probe for expression of the Xenopus Krox-20 gene. Anatomically it is evident that the development...

...M. Angela Nieto; Leila C. Bradley; David G. Wilkinson The zinc-finger gene Krox-20 is expressed in two alternating segments, rhombomeres (r) 3 and 5, in the developing mouse hindbrain. This expression pattern is established prior to rhombomere formation in the mouse, but it is not known how...