... unclear how these signals are integrated to specify discrete tissue territories. Here, we investigate the molecular mechanisms underlying the formation of one of the hindbrain segments, rhombomere (r) 3, specified by the expression of the gene krox20 . Dissecting krox20 transcriptional regulation has...

...Galya Kayam; Ayelet Kohl; Zohar Magen; Yuval Peretz; Karen Weisinger; Avi Bar; Orna Novikov; Claude Brodski; Dalit Sela-Donenfeld Complex patterns and networks of genes coordinate rhombomeric identities, hindbrain segmentation and neuronal differentiation and are responsible for later brainstem...

... and signalling pathways. Fibroblast growth factor (FGF) signalling plays a major role, notably by controlling the expression of the transcription factor Krox20 (Egr2), which is required for the formation and specification of two segmental units: rhombomeres (r) 3 and 5. Here, we explore the molecular mechanisms...

... the position-appropriate appearance of seven to eight segmental structures, known as rhombomeres (r1-r8). The evolutionarily conserved Cdx caudal-type homeodomain transcription factors help specify the vertebrate trunk and tail but have not been shown to directly regulate hindbrain patterning genes. Mafb...

...Jennifer H. Gutzman; Hazel Sive We demonstrate that in the zebrafish hindbrain, cell shape, rhombomere morphogenesis and, unexpectedly, brain ventricle lumen expansion depend on the contractile state of the neuroepithelium. The hindbrain neural tube opens in a specific sequence, with initial...

...Samuel T. Waters; Mark Lewandoski Gbx2 is a homeobox gene that plays a crucial role in positioning the mid/hindbrain organizer (isthmus), which regulates midbrain and cerebellar development primarily through the secreted factor FGF8. In Gbx2 null homozygotes, rhombomeres (r) 1-3 fail to develop...

... each rhombomere may provide AP axial information required for inner ear patterning( Brigande et al., 2000 ). An important step during early inner ear development is acquisition of axial identities from the surrounding tissues, which in turn influence the positional information and development...

... of the neural tube that had never expressed Hoxb [rhombomeres (r) 1 and 2], strongly expressed Hoxb1 but not b9 (r4), had downregulated Hoxb1 (r5), expressed Hoxb9 but not Hoxb1 (spinal cord), and expressed both genes(tail bud). We conclude that Hoxb chromatin decondensation and nuclear re-organisation...

... at interfaces between neural segments called rhombomeres (r). Mechanisms regulating segmental expression have been identified for Hox genes, but for other classes of AP patterning genes there is only limited information. We have analysed the murine retinoic acid receptor β gene ( Rarb ) and show...

...Rafael E. Hernandez; Holly A. Rikhof; Ruxandra Bachmann; Cecilia B. Moens The vertebrate hindbrain is transiently divided along the anterior-posterior axis into seven morphologically and molecularly distinct segments, or rhombomeres, that correspond to Hox expression domains. The establishment...

.... In the hindbrain,anteroposterior patterning depends on a segmentation process that leads to the formation of seven bulges called rhombomeres (r). The molecular cues involved in the early subdivision of the hindbrain and in rhombomere formation are not well understood. We show that iro7 , a zebrafish gene coding...

...Yasunori Murakami; Massimo Pasqualetti; Yoko Takio; Shigeki Hirano; Filippo M. Rijli; Shigeru Kuratani During development, the vertebrate hindbrain is subdivided along its anteroposterior axis into a series of segmental bulges called rhombomeres. These segments in turn generate a repeated pattern...

... chondrogenesis and, acting as a member of Meinox-Pbc-Hox trimers, it plays an essential role in hindbrain development. * Author for correspondence (e-mail: [email protected] ) 27 10 2003 © 2004. 2004 Vertebrate Zebrafish Hox Pbx Meis Prep Rhombomere Segmentation...

...Elizabeth L. Wiellette; Hazel Sive Vertebrate hindbrain segmentation is a highly conserved process but the mechanism of rhombomere determination is not well understood. Recent work in the zebrafish has shown a requirement for fibroblast growth factor (Fgf)signaling and for the transcription factor...

... and also immediately posterior to it in anterior rhombomere 1. Axons of the most anterior cells follow a dorsal projection, which circumnavigates the isthmus, while those of more posterior trochlear neurons project anterodorsally to enter the isthmus. Once within the isthmus, axons form large fascicles...

...Lisa Maves; William Jackman; Charles B. Kimmel The segmentation of the vertebrate hindbrain into rhombomeres is highly conserved, but how early hindbrain patterning is established is not well understood. We show that rhombomere 4 (r4) functions as an early-differentiating signaling center...

... their point of origin in hindbrain rhombomere 4 towards the posterior. By contrast, zebrafish hoxb1b , like mouse Hoxa1 , is required for proper segmental organization of rhombomere 4 and the posterior hindbrain. Double knockdown experiments demonstrate that the zebrafish hoxb1 duplicates have partially...

...Giselbert Hauptmann; Heinz-Georg Belting; Uta Wolke; Karen Lunde; Iris Söll; Salim Abdelilah-Seyfried; Victoria Prince; Wolfgang Driever Segmentation of the vertebrate hindbrain leads to the formation of a series of rhombomeres with distinct identities. In mouse, Krox20 and kreisler play important...

... strategy for interfering with Meis activity in vivo. We accomplish this by expressing the Pbx4/Lzr N-terminus, which sequesters Meis proteins in the cytoplasm away from the nuclear transcription complexes. Sequestering Meis proteins in the cytoplasm leads to extensive loss of rhombomere (r) 3- and r4...

..., the rhombomeres (r) 3 and 5. We now performed a detailed analysis of the fate of prospective r3 and r5 cells in Krox20 mutant embryos. Genetic fate mapping indicates that at least some of these cells persist in the absence of a functional Krox20 protein and uncovers the requirement for autoregulatory mechanisms...