Joachim Wittbrodt

..Already, the popularity of medaka among developmental biologists has led to important insights into vertebrate development...

..Our data indicate that the transcription factor Six3 and the replication-initiation inhibitor geminin act antagonistically to control the balance between proliferation and differentiation during early vertebrate eye development...

..To elucidate the roles of genes during embryogenesis a precise temporal control of transgene expression levels in the developing organism is on demand...

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..In this study we present an upstream survey approach, termed trans-regulation screen, to comprehensively identify the regulatory input converging on endogenous regulatory sequences...

..We further derive a model of germ layer formation and show that the mesendoderm forms from one-third of the embryo's cells in a single event. Our digital embryos, with 55 million nucleus entries, are provided as a resource...

..We propose a model of retinal morphogenesis whereby opo-mediated formation of focal contacts is required to transmit the mechanical tensions that drive the macroscopic folding of the vertebrate optic cup...

..The analysis of mutants demonstrated that the retina-specific transcription factor rx3 determines the convergence and migration behaviors of RPCs. Hence, the migration of individual cells mediates essential steps of organ morphogenesis...

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..4DXpress will be an invaluable tool for developmental as well as for computational biologists interested in gene regulation and evolution. 4DXpress is available at http://ani.embl.de/4DXpress...

..However, little is known about the direct downstream targets and, so far, no global approaches have been performed to identify these target genes in this particular tissue...

..The concerted activity of Fgf8 and Fgf3 is both necessary and sufficient to coordinate retinal differentiation independent of the connecting optic stalk...

..embl-heidelberg.de/mepd/), that is publicly accessible...

..Thus, our procedure, applied to whole genomes, is a fast and predictive tool to in silico filter the target genes of a given transcription factor with defined binding site...

..OlDach is first expressed at early somitogenesis stages in the otic placode territory and forming somites. Subsequently, expression is detected in the retina, specific regions of the central nervous system, pancreas and the finbuds...

..Based on these findings, we propose that convergent extension movements of the trunk neuroectoderm represent an ancestral feature of bilaterian development that triggered the separation of mouth and anus along the elongating trunk...

..Newly discovered motifs and their features (identity, conservation, position in sequence) are displayed on a web interface...

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..A query module that searches this list can be used to publish the screen results on the Internet. A test version is available at and the software can be downloaded from this site...

..In many cases, these studies were done in the context of pathological states like cancer as well as during vertebrate development...

..Here we present a reliable mapping panel, confirmed both by the assignment of the locus responsible for the medaka mutation eyeless/Rx3 to chromosome 12, and by the analysis of its resolution power using representative markers...

..This allows for the first time to perform high-resolution time-lapse studies in medaka...

..We also demonstrate that SPIM can be applied to visualize the embryogenesis of the relatively opaque Drosophila melanogaster in vivo...

..The fifth group consists of three mutants with defects in retinal pigmentation. The collection of mutants will be used to address the molecular genetic mechanisms underlying vertebrate eye formation...

..Comparative analysis indicates that both types of photoreceptors, with distinct opsins, coexisted in Urbilateria, the last common ancestor of insects and vertebrates, and sheds new light on vertebrate eye evolution...

..Corroborated by gain-of-function experiments, graded interference reveals an additional role of Six3 in the proximodistal patterning of the optic vesicle. During both processes of vertebrate eye formation, Six3 cooperates with Pax6...

..Thus, these mutations in orthologous genes allow us to study the evolution of vertebrate eye development at the molecular level...

..We propose that pax6-, six1/2- and ath-positive larval eyes, as found in today's trochophora, were present already in Urbilateria...

..Using these sequences, we made a Cre line that can be used for inactivation of gene expression in the developing retina...

..Later in development, OlBar transcripts are found in populations of differentiating neuronal cells of the brain and the retina...

..These data indicate that both Tle1 and Aes participate in the molecular network that control eye development and are consistent with the view that both Six3 and Six6 act in combination with either Tle1 and/or Aes...

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..Our study provides in situ insights into the properties of immature and migratory macrophages and presents a unique model to further test modulating compounds in vivo...

..Comparative analysis using different fish is thus invaluable for shedding light on evolutionary diversification of gene function...

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..They can be best explained with a model according to which zebrafish eye morphogenesis occurs as a telescopic extension of disc-like, concentric primordia, similar to the development of appendages from imaginal discs in Drosophila...

..However, the action of Xbh1 on ganglion cell development is different and more specific than that of the Xath genes, and accounts for only a part of their activities during retinogenesis...

..In this review we will illustrate how comparison of these two model species, Medaka and zebrafish, can reveal conserved and species-specific genetic and molecular mechanisms underlying vertebrate development...

..These observations suggest that many Medaka mutants represent new genes and, therefore, are important complements to the collection of zebrafish mutants that have proven so valuable for exploring genomic function in development...

..Thus, these Medaka mutants can be expected to provide clues to uncovering novel components essential for somitogenesis...

..These mutants should provide important clues to the elucidation of the molecular mechanisms underlying forebrain development, and shed new light on phylogenically conserved and divergent functions in the developmental process...

..These mutants will provide clues to understanding the functions of genes essential for axonal pathfinding, which may be conserved or partly divergent among vertebrates...

..These Medaka mutations, identified by morphological and metabolite marker screens, should provide clues to understanding molecular mechanisms underlying formation of a functional liver...

..Thus in zebrafish, trunk-derived signals are required for complete MFP formation from a common pool of organizer-derived midline precursor cells...

..Presently, MEPD has 19,757 entries, for 1024 of them the expression pattern has been determined...

..The MEPD is a project within the Medaka Genome Initiative (MGI) and entries will be interconnected to integrated genomic map databases. MEPD is accessible through the WWW at http://medaka.dsp.jst.go.jp/MEPD...