The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
William J. Sullivan - One of the best experts on this subject based on the ideXlab platform.
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RhoGEF and positioning of rappaport-like Furrows in the early Drosophila embryo.
Current biology : CB, 2012Co-Authors: Justin Crest, Kirsten Concha-moore, William J. SullivanAbstract:Early Drosophila embryogenesis is characterized by shifting from astral microtubule-based to central spindle-based positioning of cleavage Furrows. Before cellularization, astral microtubules determine metaphase furrow position by producing Rappaport-like Furrows, which encompass rather than bisect the spindle. Their positioning is explained by our finding that the conserved central spindle components centralspindlin (mKLP1 and RacGAP50C), Polo, and Fascetto (Prc1) localize to the astral microtubule overlap region. These components and the chromosomal passenger complex localize to the central spindle, though no furrow forms there. We identify the maternally supplied RhoGEF2 as a key factor in metaphase furrow positioning. Unlike the zygotic, central spindle-localized RhoGEF (Pebble), RhoGEF2 localizes to metaphase Furrows, a function distinct from RhoGEF/Pebble and likely due to the absence of a RacGAP50C binding domain. Accordingly, we find that ectopic activation of Rho GTPase generates Furrows perpendicular to the central spindle during syncytial divisions. Whereas metaphase furrow formation is myosin independent, these ectopic Furrows, like conventional Furrows, require myosin as well as microtubules. These studies demonstrate that early Drosophila embryogenesis is primed to form Furrows at either overlapping astral microtubules or the central spindle. We propose that the shift to the latter is driven by a corresponding shift from RhoGEF2 to Pebble in controlling furrow formation.
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Vesicles and actin are targeted to the cleavage furrow via furrow microtubules and the central spindle.
The Journal of cell biology, 2008Co-Authors: Roger Albertson, Taoshih Hsieh, Jian Cao, William J. SullivanAbstract:During cytokinesis, cleavage furrow invagination requires an actomyosin-based contractile ring and addition of new membrane. Little is known about how this actin and membrane traffic to the cleavage furrow. We address this through live analysis of fluorescently tagged vesicles in postcellularized Drosophila melanogaster embryos. We find that during cytokinesis, F-actin and membrane are targeted as a unit to invaginating Furrows through formation of F-actin-associated vesicles. F-actin puncta strongly colocalize with endosomal, but not Golgi-derived, vesicles. These vesicles are recruited to the cleavage furrow along the central spindle and a distinct population of microtubules (MTs) in contact with the leading furrow edge (furrow MTs). We find that Rho-specific guanine nucleotide exchange factor mutants, pebble (pbl), severely disrupt this F-actin-associated vesicle transport. These transport defects are a consequence of the pbl mutants' inability to properly form furrow MTs and the central spindle. Transport of F-actin-associated vesicles on furrow MTs and the central spindle is thus an important mechanism by which actin and membrane are delivered to the cleavage furrow.
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the drosophila centrosomal protein nuf is required for recruiting dah a membrane associated protein to Furrows in the early embryo
Journal of Cell Science, 1999Co-Authors: Wendy F Rothwell, Claire X Zhang, Christina Zelano, Taoshih Hsieh, William J. SullivanAbstract:During mitosis of the Drosophila cortical syncytial divisions, actin-based membrane Furrows separate adjacent spindles. Our genetic analysis indicates that the centrosomal protein Nuf is specifically required for recruitment of components to the Furrows and the membrane-associated protein Dah is primarily required for the inward invagination of the furrow membrane. Recruitment of actin, anillin and peanut to the Furrows occurs normally in dah-derived embryos. However, subsequent invagination of the Furrows fails in dah-derived embryos and the septins become dispersed throughout the cytoplasm. This indicates that stable septin localization requires Dah-mediated furrow invagination. Close examination of actin and Dah localization in wild-type embryos reveals that they associate in adjacent particles during interphase and co-localize in the invaginating Furrows during prophase and metaphase. We show that the Nuf centrosomal protein is required for recruiting the membrane-associated protein Dah to the Furrows. In nuf-mutant embryos, much of the Dah does not reach the Furrows and remains in a punctate distribution. This suggests that Dah is recruited to the Furrows in vesicles and that the recruiting step is disrupted in nuf mutants. These studies lead to a model in which the centrosomes play an important role in the transport of membrane-associated proteins and other components to the developing Furrows.
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nuclear fallout a drosophila protein that cycles from the cytoplasm to the centrosomes regulates cortical microfilament organization
Development, 1998Co-Authors: Wendy F Rothwell, Patrick Fogarty, Christine M Field, William J. SullivanAbstract:nuclear fallout (nuf) is a maternal effect mutation that specifically disrupts the cortical syncytial divisions during Drosophila embryogenesis. We show that the nuf gene encodes a highly phosphorylated novel protein of 502 amino acids with C-terminal regions predicted to form coiled-coils. During prophase of the late syncytial divisions, Nuf concentrates at the centrosomes and is generally cytoplasmic throughout the rest of the nuclear cycle. In nuf-derived embryos, the recruitment of actin from caps to Furrows during prophase is disrupted. This results in incomplete metaphase Furrows specifically in regions distant from the centrosomes. The nuf mutation does not disrupt anillin or peanut recruitment to the metaphase Furrows indicating that Nuf is not involved in the signaling of metaphase furrow formation. These results also suggest that anillin and peanut localization are independent of actin localization to the metaphase Furrows. nuf also disrupts the initial stages of cellularization and produces disruptions in cellularization Furrows similar to those observed in the metaphase Furrows. The localization of Nuf to centrosomal regions throughout cellularization suggests that it plays a similar role in the initial formation of both metaphase and cellularization Furrows. A model is presented in which Nuf provides a functional link between centrosomes and microfilaments.
Michael Glotzer - One of the best experts on this subject based on the ideXlab platform.
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local rhoa activation induces cytokinetic Furrows independent of spindle position and cell cycle stage
Journal of Cell Biology, 2016Co-Authors: Elizabeth Wagner, Michael GlotzerAbstract:The GTPase RhoA promotes contractile ring assembly and furrow ingression during cytokinesis. Although many factors that regulate RhoA during cytokinesis have been characterized, the spatiotemporal regulatory logic remains undefined. We have developed an optogenetic probe to gain tight spatial and temporal control of RhoA activity in mammalian cells and demonstrate that cytokinetic furrowing is primarily regulated at the level of RhoA activation. Light-mediated recruitment of a RhoGEF domain to the plasma membrane leads to rapid induction of RhoA activity, leading to assembly of cytokinetic Furrows that partially ingress. Furthermore, furrow formation in response to RhoA activation is not temporally or spatially restricted. RhoA activation is sufficient to generate Furrows at both the cell equator and cell poles, in both metaphase and anaphase. Remarkably, furrow formation can be initiated in rounded interphase cells, but not adherent cells. These results indicate that RhoA activation is sufficient to induce assembly of functional contractile rings and that cell rounding facilitates furrow formation.
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local rhoa activation induces cytokinetic Furrows independent of spindle position and cell cycle stage
bioRxiv, 2016Co-Authors: Elizabeth Wagner, Michael GlotzerAbstract:Cytokinetic cleavage Furrows assemble during anaphase at a site that is dictated by the position of the spindle. The GTPase RhoA promotes contractile ring assembly and furrow ingression during cytokinesis. While many factors that regulate RhoA during cytokinesis have been characterized, the spatiotemporal regulatory logic remains undefined. It is not known whether a local zone of RhoA activity is sufficient to induce furrow formation or whether the spindle modulates furrow assembly through other pathways. Similarly, it is not known whether the entire cortex is responsive to RhoA, nor whether contractile ring assembly is cell cycle regulated. Here, we have developed an optogenetic probe to gain tight spatial and temporal control of RhoA activity in mammalian cells and demonstrate that cytokinetic furrowing is primarily regulated at the level of RhoA activation. Light-mediated recruitment of a RhoGEF domain to the plasma membrane leads to rapid activation of RhoA, leading to assembly of cytokinetic Furrows that partially ingress. Furthermore, furrow formation in response to RhoA activation is not spatially or temporally restricted. RhoA activation is sufficient to generate Furrows at both the cell equator and at cell poles, in both metaphase and anaphase. Remarkably, furrow formation can be initiated in rounded interphase cells, but not adherent cells. These results indicate RhoA activation is sufficient to induce assembly of functional contractile rings and that cell rounding facilitates furrow formation.
Qinge Dong - One of the best experts on this subject based on the ideXlab platform.
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alternating wide ridges and narrow Furrows with film mulching improves soil hydrothermal conditions and maize water use efficiency in dry sub humid regions
Agricultural Water Management, 2021Co-Authors: Chenxiao Duan, Guangjie Chen, Hao Feng, Qinge DongAbstract:Abstract The ridge-furrow mulching system (RFMS) is widely used to improve crop yields and water use efficiency in arid and semi-arid rainfed agricultural regions. However, the effects of RFMS on hydrothermal states and maize (Zea mays L.) yields in dry sub-humid regions remain unclear. The objective of this study was to determine the influence of ridge-furrow construction and plastic film mulching on soil moisture and temperature, evapotranspiration (ET), maize growth and yield, water use efficiency (WUE), and thermal time use efficiency (TUE) in dry sub-humid regions of the Loess Plateau. A three-year field study was conducted in which four different planting practices were evaluated: (1) alternating wide ridges and narrow Furrows with film mulching (WRM), (2) alternating equal-width ridges and Furrows with film mulching (ERM), (3) equal row spacing in flat plot with half film mulching (EFM), and (4) conventional flat plot without mulching (CK). The results demonstrated that at early maize growth stages, soil water storage within the 0–200 cm soil profile and soil temperatures were increased for mulching treatments compared with CK. RFMS utilized soil water efficiently by increasing rainwater harvesting efficiency and transpiration while decreasing soil evaporation. RFMS significantly increased soil temperature in the ridges by 4.0–4.4 °C and reduced diurnal soil temperature amplitude in the Furrows, thereby increasing soil thermal time. These positive effects of RFMS compared with CK improved maize growth and crop yields because of adequate absorption and utilization of water and thermal resources. RFMS increased average maize yield by 24.9–32.8%, WUE by 34.1–45.7%, and TUE by 15.9–21.1%. The highest grain yield, WUE, and TUE were observed with WRM due to its favorable soil hydrothermal conditions. The WRM treatment is a promising water-saving and high-yielding maize cultivation practice to improve grain yields and resource use efficiency in dry sub-humid regions.
Günther Gerisch - One of the best experts on this subject based on the ideXlab platform.
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Unilateral Cleavage Furrows in Multinucleate Cells.
Cells, 2020Co-Authors: Julia Bindl, Eszter Molnár, Mary Ecke, Jana Prassler, Annette Müller-taubenberger, Günther GerischAbstract:Multinucleate cells can be produced in Dictyostelium by electric pulse-induced fusion. In these cells, unilateral cleavage Furrows are formed at spaces between areas that are controlled by aster microtubules. A peculiarity of unilateral cleavage Furrows is their propensity to join laterally with other Furrows into rings to form constrictions. This means cytokinesis is biphasic in multinucleate cells, the final abscission of daughter cells being independent of the initial direction of furrow progression. Myosin-II and the actin filament cross-linking protein cortexillin accumulate in unilateral Furrows, as they do in the normal cleavage Furrows of mononucleate cells. In a myosin-II-null background, multinucleate or mononucleate cells were produced by cultivation either in suspension or on an adhesive substrate. Myosin-II is not essential for cytokinesis either in mononucleate or in multinucleate cells but stabilizes and confines the position of the cleavage Furrows. In fused wild-type cells, unilateral Furrows ingress with an average velocity of 1.7 µm × min-1, with no appreciable decrease of velocity in the course of ingression. In multinucleate myosin-II-null cells, some of the Furrows stop growing, thus leaving space for the extensive broadening of the few remaining Furrows.
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Unilateral Cleavage Furrows in Multinucleate Cells
2020Co-Authors: Julia Bindl, Eszter Molnár, Mary Ecke, Jana Prassler, Annette Müller-taubenberger, Günther GerischAbstract:Multinucleate cells can be produced in Dictyostelium by electric-pulse induced fusion. In these cells unilateral cleavage Furrows are formed at spaces between areas that are controlled by aster microtubules. A peculiarity of unilateral cleavage Furrows is their propensity to join laterally with other Furrows into rings to form constrictions. This means, cytokinesis is biphasic in multinucleate cells, the final abscission of daughter cells being independent of the initial direction of furrow progression. Myosin-II and the actin-filament cross-linking protein cortexillin accumulate in the unilateral Furrows, as they do in the normal cleavage Furrows of mononucleate cells. Myosin-II is not essential for cytokinesis, but stabilizes and confines the position of the cleavage Furrows.
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microtubule mediated centrosome motility and the positioning of cleavage Furrows in multinucleate myosin ii null cells
Journal of Cell Science, 1998Co-Authors: Ralph Neujahr, Richard Albrecht, Jana Kohler, Monika Matzner, Jeanmarc Schwartz, Monika Westphal, Günther GerischAbstract:To study centrosome motility and the interaction of microtubules with the cell cortex in mitotic, post-mitotic and interphase cells, (alpha)-tubulin was tagged in Dictyostelium discoideum with green fluorescent protein. Multinucleate cells formed by myosin II-null mutants proved to be especially suited for the analysis of the control of cleavage furrow formation by the microtubule system. After docking of the mitotic apparatus onto the cell cortex during anaphase, the cell surface is activated to form ruffles on top of the asters of microtubules that emanate from the centrosomes. Cleavage Furrows are initiated at spaces between the asters independently of the positions of spindles. Once initiated, the Furrows expand as deep folds without a continued connection to the microtubule system. Occurrence of unilateral Furrows indicates that a closed contractile ring is dispensable for cytokinesis in Dictyostelium. The progression of cytokinesis in the multinucleate cells underlines the importance of proteins other than myosin II in specifying a cleavage furrow. The analysis of centrosome motility suggests a major role for a minus-end directed motor protein, probably cytoplasmic dynein, in applying traction forces on guiding microtubules that connect the centrosome with the cell cortex.
Elizabeth Wagner - One of the best experts on this subject based on the ideXlab platform.
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local rhoa activation induces cytokinetic Furrows independent of spindle position and cell cycle stage
Journal of Cell Biology, 2016Co-Authors: Elizabeth Wagner, Michael GlotzerAbstract:The GTPase RhoA promotes contractile ring assembly and furrow ingression during cytokinesis. Although many factors that regulate RhoA during cytokinesis have been characterized, the spatiotemporal regulatory logic remains undefined. We have developed an optogenetic probe to gain tight spatial and temporal control of RhoA activity in mammalian cells and demonstrate that cytokinetic furrowing is primarily regulated at the level of RhoA activation. Light-mediated recruitment of a RhoGEF domain to the plasma membrane leads to rapid induction of RhoA activity, leading to assembly of cytokinetic Furrows that partially ingress. Furthermore, furrow formation in response to RhoA activation is not temporally or spatially restricted. RhoA activation is sufficient to generate Furrows at both the cell equator and cell poles, in both metaphase and anaphase. Remarkably, furrow formation can be initiated in rounded interphase cells, but not adherent cells. These results indicate that RhoA activation is sufficient to induce assembly of functional contractile rings and that cell rounding facilitates furrow formation.
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local rhoa activation induces cytokinetic Furrows independent of spindle position and cell cycle stage
bioRxiv, 2016Co-Authors: Elizabeth Wagner, Michael GlotzerAbstract:Cytokinetic cleavage Furrows assemble during anaphase at a site that is dictated by the position of the spindle. The GTPase RhoA promotes contractile ring assembly and furrow ingression during cytokinesis. While many factors that regulate RhoA during cytokinesis have been characterized, the spatiotemporal regulatory logic remains undefined. It is not known whether a local zone of RhoA activity is sufficient to induce furrow formation or whether the spindle modulates furrow assembly through other pathways. Similarly, it is not known whether the entire cortex is responsive to RhoA, nor whether contractile ring assembly is cell cycle regulated. Here, we have developed an optogenetic probe to gain tight spatial and temporal control of RhoA activity in mammalian cells and demonstrate that cytokinetic furrowing is primarily regulated at the level of RhoA activation. Light-mediated recruitment of a RhoGEF domain to the plasma membrane leads to rapid activation of RhoA, leading to assembly of cytokinetic Furrows that partially ingress. Furthermore, furrow formation in response to RhoA activation is not spatially or temporally restricted. RhoA activation is sufficient to generate Furrows at both the cell equator and at cell poles, in both metaphase and anaphase. Remarkably, furrow formation can be initiated in rounded interphase cells, but not adherent cells. These results indicate RhoA activation is sufficient to induce assembly of functional contractile rings and that cell rounding facilitates furrow formation.
