Tsikolia, Nikoloz

[["dc.bibliographiccitation.artnumber","4"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","EvoDevo"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Kremnyov, Stanislav"],["dc.contributor.author","Viebahn, Christoph"],["dc.contributor.author","Tsikolia, Nikoloz"],["dc.contributor.author","Henningfeld, Kristine A."],["dc.date.accessioned","2018-04-18T14:43:20Z"],["dc.date.accessioned","2021-10-27T13:21:04Z"],["dc.date.available","2018-04-18T14:43:20Z"],["dc.date.available","2021-10-27T13:21:04Z"],["dc.date.issued","2018-01-31"],["dc.date.updated","2018-04-18T14:43:20Z"],["dc.description.abstract","Abstract Background The notochord has organizer properties and is required for floor plate induction and dorsoventral patterning of the neural tube. This activity has been attributed to sonic hedgehog (shh) signaling, which originates in the notochord, forms a gradient, and autoinduces shh expression in the floor plate. However, reported data are inconsistent and the spatiotemporal development of the relevant shh expression domains has not been studied in detail. We therefore studied the expression dynamics of shh in rabbit, chicken and Xenopus laevis embryos (as well as indian hedgehog and desert hedgehog as possible alternative functional candidates in the chicken). Results Our analysis reveals a markedly divergent pattern within these vertebrates: whereas in the rabbit shh is first expressed in the notochord and its floor plate domain is then induced during subsequent somitogenesis stages, in the chick embryo shh is expressed in the prospective neuroectoderm prior to the notochord formation and, interestingly, prior to mesoderm immigration. Neither indian hedgehog nor desert hedgehog are expressed in these midline structures although mRNA of both genes was detected in other structures of the early chick embryo. In X. laevis, shh is expressed at the beginning of gastrulation in a distinct area dorsal to the dorsal blastopore lip and adjacent to the prospective neuroectoderm, whereas the floor plate expresses shh at the end of gastrulation. Conclusions While shh expression patterns in rabbit and X. laevis embryos are roughly compatible with the classical view of “ventral to dorsal induction” of the floor plate, the early shh expression in the chick floor plate challenges this model. Intriguingly, this alternative sequence of domain induction is related to the asymmetrical morphogenesis of the primitive node and other axial organs in the chick. Our results indicate that the floor plate in X. laevis and chick embryos may be initially induced by planar interaction within the ectoderm or epiblast. Furthermore, we propose that the mode of the floor plate induction adapts to the variant topography of interacting tissues during gastrulation and notochord formation and thereby reveals evolutionary plasticity of early embryonic induction."],["dc.identifier.doi","10.1186/s13227-017-0090-x"],["dc.identifier.pmid","29423139"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15170"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/91992"],["dc.language.iso","en"],["dc.language.rfc3066","en"],["dc.notes.intern","Migrated from goescholar"],["dc.relation.issn","2041-9139"],["dc.relation.orgunit","Universitätsmedizin Göttingen"],["dc.rights","CC BY 4.0"],["dc.rights.holder","The Author(s)"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.ddc","610"],["dc.title","Divergent axial morphogenesis and early shh expression in vertebrate prospective floor plate"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","496"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Developmental Dynamics"],["dc.bibliographiccitation.lastpage","508"],["dc.bibliographiccitation.volume","249"],["dc.contributor.author","Pieper, Tobias"],["dc.contributor.author","Carpaij, Meriam"],["dc.contributor.author","Reinermann, Johanna"],["dc.contributor.author","Surchev, Lachezar"],["dc.contributor.author","Viebahn, Christoph"],["dc.contributor.author","Tsikolia, Nikoloz"],["dc.date.accessioned","2019-12-16T11:15:39Z"],["dc.date.accessioned","2021-10-27T13:21:54Z"],["dc.date.available","2019-12-16T11:15:39Z"],["dc.date.available","2021-10-27T13:21:54Z"],["dc.date.issued","2019"],["dc.description.abstract","BACKGROUND: Hensen node of the amniote embryo plays a central role in multiple developmental processes, especially in induction and formation of axial organs. In the chick, it is asymmetrical in shape and has recently been considered to represent the left-right organizer. As mechanisms of breaking the initial left-right symmetry of the embryo are still ill-understood, analyzing the node's microarchitecture may provide insights into functional links between symmetry breaking and asymmetric morphology. RESULTS: In the course of a light- and electron-microscopic study addressing this issue we discovered novel intercellular matrix-filled cavities in the node of the chick during gastrulation and during early neurulation stages; measuring up to 45 μm, they are surrounded by densely packed cells and filled with nanoscale fibrils, which immunostaining suggests to consist of the basement membrane-related proteins fibronectin and perlecan. The cavities emerge immediately prior to node formation in the epiblast layer adjacent to the tip of the primitive streak and later, with emerging node asymmetry, they are predominantly located in the right part of the node. Almost identical morphological features of microcavities were found in the duck node. CONCLUSIONS: We address these cavities as \"nodal microcavities\" and propose their content to be involved in the function of the avian node by mediating morphogen signaling and storage."],["dc.identifier.doi","10.1002/dvdy.133"],["dc.identifier.eissn","1097-0177"],["dc.identifier.issn","1058-8388"],["dc.identifier.pmid","31729123"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16941"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/92053"],["dc.language.iso","en"],["dc.notes.intern","Migrated from goescholar"],["dc.publisher","John Wiley \\u0026 Sons, Inc."],["dc.relation.eissn","1097-0177"],["dc.relation.issn","1553-0795"],["dc.relation.issn","1058-8388"],["dc.relation.orgunit","Universitätsmedizin Göttingen"],["dc.rights","CC BY-NC 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/4.0"],["dc.subject.ddc","610"],["dc.title","Matrix‐filled microcavities in the emerging avian left‐right organizer"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]