The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Benedicte Sanson - One of the best experts on this subject based on the ideXlab platform.
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unipolar distributions of junctional myosin ii identify cell stripe boundaries that drive cell intercalation throughout drosophila axis Extension
eLife, 2016Co-Authors: Robert J Tetley, Guy B Blanchard, Richard J Adams, Alexander G Fletcher, Benedicte SansonAbstract:Convergence and Extension movements elongate tissues during development. Drosophila Germ-Band Extension (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. Here, we develop novel computational methods to analyse the spatiotemporal dynamics of Myosin II during GBE, at the scale of the tissue. We show that initial Myosin II bipolar cell polarization gives way to unipolar enrichment at parasegmental boundaries and two further boundaries within each parasegment, concomitant with a doubling of cell number as the tissue elongates. These boundaries are the primary sites of cell intercalation, behaving as mechanical barriers and providing a mechanism for how cells remain ordered during GBE. Enrichment at parasegment boundaries during GBE is independent of Wingless signaling, suggesting pair-rule gene control. Our results are consistent with recent work showing that a combinatorial code of Toll-like receptors downstream of pair-rule genes contributes to Myosin II polarization via local cell-cell interactions. We propose an updated cell-cell interaction model for Myosin II polarization that we tested in a vertex-based simulation.
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cell shape changes indicate a role for extrinsic tensile forces in drosophila germ band Extension
Nature Cell Biology, 2009Co-Authors: Lucy Butler, Guy B Blanchard, Alexandre Kabla, Nicola Lawrence, David P Welchman, L Mahadevan, Richard J Adams, Benedicte SansonAbstract:Drosophila Germ-Band Extension (GBE) is an example of the convergence and Extension movements that elongate and narrow embryonic tissues. To understand the collective cell behaviours underlying tissue morphogenesis, we have continuously quantified cell intercalation and cell shape change during GBE. We show that the fast, early phase of GBE depends on cell shape change in addition to cell intercalation. In antero-posterior patterning mutants such as those for the gap gene Kruppel, defective polarized cell intercalation is compensated for by an increase in antero-posterior cell elongation, such that the initial rate of Extension remains the same. Spatio-temporal patterns of cell behaviours indicate that an antero-posterior tensile force deforms the germ band, causing the cells to change shape passively. The rate of antero-posterior cell elongation is reduced in twist mutant embryos, which lack mesoderm. We propose that cell shape change contributing to Germ-Band Extension is a passive response to mechanical forces caused by the invaginating mesoderm.
Markus Noll - One of the best experts on this subject based on the ideXlab platform.
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the polycomb group gene extra sex combs encodes a nuclear member of the wd 40 repeat family
The EMBO Journal, 1995Co-Authors: Thomas Gutjahr, Erich Frei, C Spicer, Stefan Baumgartner, R A White, Markus NollAbstract:We have delimited the extra sex combs (esc) gene to < 4 kb that include a single transcript and are able to rescue both the maternal and zygotic esc phenotypes. Several mutations have been identified within the esc transcript. In agreement with earlier genetic studies, esc is expressed maternally and its product is most abundant during the early embryonic stages. It encodes a protein of the WD-40 repeat family, which localizes predominantly to the nucleus. During germ band Extension, it is expressed in a stereotypic pattern of neuroblasts. We propose a model in which Esc is recruited by gap proteins both to act as a corepressor that competes with the TAFII80 coactivator to block transcription and also to mediate the transition to permanent repression by Polycomb-group proteins.
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analysis of the gooseberry locus in drosophila embryos gooseberry determines the cuticular pattern and activates gooseberry neuro
Development, 1993Co-Authors: Thomas Gutjahr, Nipam H Patel, Xuelin Li, Corey S Goodman, Markus NollAbstract:The segment-polarity class of segmentation genes in Drosophila are primarily involved in the specification of sub-segmental units. In addition, some of the segmentpolarity genes have been shown to specify cell fates within the central nervous system. One of these loci, gooseberry, consists of two divergently transcribed genes, gooseberry and gooseberry neuro, which share a paired box as well as a paired-type homeobox. Here, the expression patterns of the two gooseberry gene products are described in detail. The gooseberry protein appears in a characteristic segment-polarity pattern of stripes at gastrulation and persists until head involution. It is initially restricted to the ectodermal and neuroectodermal germ layer, but is later detected in mesodermal and neuronal cells as well. The gooseberry neuro protein first appears during germ band Extension in cells of the central nervous system and also, much later, in epidermal stripes and in a small number of muscle cells. P-elementmediated transformation with the gooseberry gene has been used to demonstrate that gooseberry transactivates gooseberry neuro and is sufficient to rescue the gooseberry cuticular phenotype in the absence of gooseberry neuro. SUMMARY
Thomas Gutjahr - One of the best experts on this subject based on the ideXlab platform.
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the polycomb group gene extra sex combs encodes a nuclear member of the wd 40 repeat family
The EMBO Journal, 1995Co-Authors: Thomas Gutjahr, Erich Frei, C Spicer, Stefan Baumgartner, R A White, Markus NollAbstract:We have delimited the extra sex combs (esc) gene to < 4 kb that include a single transcript and are able to rescue both the maternal and zygotic esc phenotypes. Several mutations have been identified within the esc transcript. In agreement with earlier genetic studies, esc is expressed maternally and its product is most abundant during the early embryonic stages. It encodes a protein of the WD-40 repeat family, which localizes predominantly to the nucleus. During germ band Extension, it is expressed in a stereotypic pattern of neuroblasts. We propose a model in which Esc is recruited by gap proteins both to act as a corepressor that competes with the TAFII80 coactivator to block transcription and also to mediate the transition to permanent repression by Polycomb-group proteins.
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analysis of the gooseberry locus in drosophila embryos gooseberry determines the cuticular pattern and activates gooseberry neuro
Development, 1993Co-Authors: Thomas Gutjahr, Nipam H Patel, Xuelin Li, Corey S Goodman, Markus NollAbstract:The segment-polarity class of segmentation genes in Drosophila are primarily involved in the specification of sub-segmental units. In addition, some of the segmentpolarity genes have been shown to specify cell fates within the central nervous system. One of these loci, gooseberry, consists of two divergently transcribed genes, gooseberry and gooseberry neuro, which share a paired box as well as a paired-type homeobox. Here, the expression patterns of the two gooseberry gene products are described in detail. The gooseberry protein appears in a characteristic segment-polarity pattern of stripes at gastrulation and persists until head involution. It is initially restricted to the ectodermal and neuroectodermal germ layer, but is later detected in mesodermal and neuronal cells as well. The gooseberry neuro protein first appears during germ band Extension in cells of the central nervous system and also, much later, in epidermal stripes and in a small number of muscle cells. P-elementmediated transformation with the gooseberry gene has been used to demonstrate that gooseberry transactivates gooseberry neuro and is sufficient to rescue the gooseberry cuticular phenotype in the absence of gooseberry neuro. SUMMARY
Markus Affolter - One of the best experts on this subject based on the ideXlab platform.
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myosin ii is not required for drosophila tracheal branch elongation and cell intercalation
Development, 2017Co-Authors: Amanda Ochoaespinosa, Stefan Harmansa, Emmanuel Caussinus, Markus AffolterAbstract:The Drosophila tracheal system consists of an interconnected network of monolayered epithelial tubes that ensures oxygen transport in the larval and adult body. During tracheal dorsal branch (DB) development, individual DBs elongate as a cluster of cells, led by tip cells at the front and trailing cells in the rear. Branch elongation is accompanied by extensive cell intercalation and cell lengthening of the trailing stalk cells. Although cell intercalation is governed by Myosin II (MyoII)-dependent forces during tissue elongation in the Drosophila embryo that lead to Germ-Band Extension, it remained unclear whether MyoII plays a similar active role during tracheal branch elongation and intercalation. Here, we have used a nanobody-based approach to selectively knock down MyoII in tracheal cells. Our data show that, despite the depletion of MyoII function, tip cell migration and stalk cell intercalation (SCI) proceed at a normal rate. This confirms a model in which DB elongation and SCI in the trachea occur as a consequence of tip cell migration, which produces the necessary forces for the branching process.
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myosin ii activity is not required for drosophila tracheal branching morphogenesis
bioRxiv, 2017Co-Authors: Amanda Ochoaespinosa, Stefan Harmansa, Emmanuel Caussinus, Markus AffolterAbstract:The Drosophila tracheal system consists of an interconnected network of monolayered epithelial tubes that ensures oxygen transport in the larval and adult body. During tracheal dorsal branch (DB) development, individual DBs elongate as a cluster of cells, led by tip cells at the front and trailing cells in the rear. Branch elongation is accompanied by extensive cell intercalation and cell lengthening of the trailing stalk cells. While cell intercalation is governed by Myosin II (MyoII)-dependent forces during tissue elongation in the Drosophila embryo leading to Germ-Band Extension, it remained unclear whether MyoII plays a similar active role during tracheal branch elongation and intercalation. Here, we use a nanobody-based approach to selectively knock-down MyoII in tracheal cells. Our data shows that despite the depletion of MyoII function, tip cells migration and stalk cell intercalation (SCI) proceeds at a normal rate. Therefore, our data confirms a model in which DB elongation and SCI in the trachea occurs as a consequence of tip cell migration, which produces the necessary forces for the branching process.
Guy B Blanchard - One of the best experts on this subject based on the ideXlab platform.
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unipolar distributions of junctional myosin ii identify cell stripe boundaries that drive cell intercalation throughout drosophila axis Extension
eLife, 2016Co-Authors: Robert J Tetley, Guy B Blanchard, Richard J Adams, Alexander G Fletcher, Benedicte SansonAbstract:Convergence and Extension movements elongate tissues during development. Drosophila Germ-Band Extension (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. Here, we develop novel computational methods to analyse the spatiotemporal dynamics of Myosin II during GBE, at the scale of the tissue. We show that initial Myosin II bipolar cell polarization gives way to unipolar enrichment at parasegmental boundaries and two further boundaries within each parasegment, concomitant with a doubling of cell number as the tissue elongates. These boundaries are the primary sites of cell intercalation, behaving as mechanical barriers and providing a mechanism for how cells remain ordered during GBE. Enrichment at parasegment boundaries during GBE is independent of Wingless signaling, suggesting pair-rule gene control. Our results are consistent with recent work showing that a combinatorial code of Toll-like receptors downstream of pair-rule genes contributes to Myosin II polarization via local cell-cell interactions. We propose an updated cell-cell interaction model for Myosin II polarization that we tested in a vertex-based simulation.
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cell shape changes indicate a role for extrinsic tensile forces in drosophila germ band Extension
Nature Cell Biology, 2009Co-Authors: Lucy Butler, Guy B Blanchard, Alexandre Kabla, Nicola Lawrence, David P Welchman, L Mahadevan, Richard J Adams, Benedicte SansonAbstract:Drosophila Germ-Band Extension (GBE) is an example of the convergence and Extension movements that elongate and narrow embryonic tissues. To understand the collective cell behaviours underlying tissue morphogenesis, we have continuously quantified cell intercalation and cell shape change during GBE. We show that the fast, early phase of GBE depends on cell shape change in addition to cell intercalation. In antero-posterior patterning mutants such as those for the gap gene Kruppel, defective polarized cell intercalation is compensated for by an increase in antero-posterior cell elongation, such that the initial rate of Extension remains the same. Spatio-temporal patterns of cell behaviours indicate that an antero-posterior tensile force deforms the germ band, causing the cells to change shape passively. The rate of antero-posterior cell elongation is reduced in twist mutant embryos, which lack mesoderm. We propose that cell shape change contributing to Germ-Band Extension is a passive response to mechanical forces caused by the invaginating mesoderm.