The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Gregory A Smith - One of the best experts on this subject based on the ideXlab platform.
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the Apical Region of the herpes simplex virus major capsid protein promotes capsid maturation
Journal of Virology, 2018Co-Authors: Laura Lee Ruhge, Alexis Huet, James F Conway, Gregory A SmithAbstract:The herpesvirus capsid assembles in the nucleus as an immature procapsid precursor built around viral scaffold proteins. The event that initiates procapsid maturation is unknown, but it is dependent upon activation of the VP24 internal protease. Scaffold cleavage triggers angularization of the shell and its decoration with the VP26 and pUL25 capsid-surface proteins. In both the procapsid and mature angularized capsid, the Apical Region of the major capsid protein (VP5) is surface exposed. We investigated whether the VP5 Apical Region contributes to intracellular transport dynamics following entry into primary sensory neurons and also tested the hypothesis that conserved negatively charged amino acids in the Apical Region contribute to VP26 acquisition. To our surprise, neither hypothesis proved true. Instead, mutation of glutamic acid residues in the Apical Region delayed viral propagation and induced focal capsid accumulations in nuclei. Examination of capsid morphogenesis based on epitope unmasking, capsid composition, and ultrastructural analysis indicated that these clusters consisted of procapsids. The results demonstrate that, in addition to established events that occur inside the capsid, the exterior capsid shell promotes capsid morphogenesis and maturation. IMPORTANCE Herpesviruses assemble capsids and encapsidate their genomes by a process that is unlike those of other mammalian viruses but is similar to those of some bacteriophage. Many important aspects of herpesvirus morphogenesis remain enigmatic, including how the capsid shell matures into a stable angularized configuration. Capsid maturation is triggered by activation of a protease that cleaves an internal protein scaffold. We report on the fortuitous discovery that a Region of the major capsid protein that is exposed on the outer surface of the capsid also contributes to capsid maturation, demonstrating that the morphogenesis of the capsid shell from its procapsid precursor to the mature angularized form is dependent upon internal and external components of the megastructure.
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the Apical Region of the herpes simplex virus major capsid protein promotes capsid maturation
bioRxiv, 2018Co-Authors: Laura Lee Ruhge, Alexis Huet, James F Conway, Gregory A SmithAbstract:The herpesvirus capsid assembles in the nucleus as an immature procapsid precursor built around viral scaffold proteins. The event that initiates procapsid maturation is unknown, but it is dependent upon activation of the VP24 internal protease. Scaffold cleavage triggers angularization of the shell and its decoration with the VP26 and pUL25 capsid-surface proteins. In both the procapsid and mature angularized capsid, the Apical Region of the major capsid protein (VP5) is surface exposed. We investigated whether the VP5 Apical Region contributes to intracellular transport dynamics following entry into primary sensory neurons and also tested the hypothesis that conserved negatively-charged amino acids in the Apical Region contribute to VP26 acquisition. To our surprise neither hypothesis proved true. Instead, mutation of glutamic acid residues in the Apical Region delayed viral propagation and induced focal capsid accumulations in nuclei. Examination of capsid morphogenesis based on epitope unmasking, capsid composition, and ultrastructural analysis indicated that these clusters consisted of procapsids. The results demonstrate that, in addition to established events that occur inside the capsid, the exterior capsid shell promotes capsid morphogenesis and maturation.
Djoko Suharto - One of the best experts on this subject based on the ideXlab platform.
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visualization of removal of trapped air from the Apical Region in simulated root canals by laser activated irrigation using an er cr ysgg laser
Lasers in Medical Science, 2015Co-Authors: Harry Huiz Peeters, Roeland De Moor, Djoko SuhartoAbstract:The aim of this visualization study was to obtain a better understanding of the mechanism by which trapped air is removed from the Apical Region of simulated root canals by activation of an irrigant using an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser during endodontic procedures. A high-speed imaging system with high temporal and spatial resolution was used to visualize laser-induced shock waves in a resin block model with a curved root canal (inner diameter at the apex 0.08 mm, taper 4 %, crown height 10 mm, overall length 40 mm) and a glass cylinder model with a straight root canal (inner diameter 1 mm, crown height 10 mm, overall length 40 mm). The study utilized MZ3 and RFT3 tips in each model, without water or air spray, and with an average power of 1 W at 35 Hz. Laser-activated irrigation overcame the airlock effect by releasing air trapped in the air column. The mechanism underlying the removal of trapped air from the Apical Region using an Er,Cr:YSGG laser in a dry root canal is via the disruption of the surface tension at the solution-air interface. This disruption, caused by bubble implosion (cavitation), displaces air in the form of bubbles from the Apical Region toward the solution, which allows the solution to travel Apically.
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visualization of removal of trapped air from the Apical Region of the straight root canal models generating 2 phase intermittent counter flow during ultrasonically activated irrigation
Journal of Endodontics, 2014Co-Authors: Harry Huiz Peeters, Bernard Ongki Iskandar, Ketut Suardita, Djoko SuhartoAbstract:Abstract Introduction The purpose of this in vitro study was to obtain a better understanding of the mechanism of irrigant traveling Apically and generating 2-phase intermittent counter flow in straight root canal models during activation of the irrigant by ultrasonic means in an endodontic procedure. Methods A high-speed imaging system, with high temporal and spatial resolution (FastCam SA5; Photron, Tokyo, Japan) at a frame rate of 100,000 frames per second using a macro lens (60 mm, f/2.8; Nikon, Tokyo, Japan), was used to visualize, in glass models of root canals, an ultrasonically induced acoustic pressure wave in an EDTA solution environment. A 25-mm stainless steel noncutting file #20 driven by an ultrasonic device (P5 Newtron; Satelec Acteon, Merignac, France) at power settings of 5 and 7 produced disturbances at the solution-air interface. Results We found that Apically directed travel of the irrigant was caused by disruption of the surface tension at the solution-air interface. This disruption caused by ultrasonic activation energy displaced air in the form of bubbles from the Apical Region toward the solution. Conclusions The Apical movement of the solution may be attributed to ultrasonically induced wave generation at the solution-air interface, resulting in the removal of trapped air from the root canal and allowing the solution to travel Apically in the opposite directions (via a 2-phase intermittent counter flow).
Laura Lee Ruhge - One of the best experts on this subject based on the ideXlab platform.
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the Apical Region of the herpes simplex virus major capsid protein promotes capsid maturation
Journal of Virology, 2018Co-Authors: Laura Lee Ruhge, Alexis Huet, James F Conway, Gregory A SmithAbstract:The herpesvirus capsid assembles in the nucleus as an immature procapsid precursor built around viral scaffold proteins. The event that initiates procapsid maturation is unknown, but it is dependent upon activation of the VP24 internal protease. Scaffold cleavage triggers angularization of the shell and its decoration with the VP26 and pUL25 capsid-surface proteins. In both the procapsid and mature angularized capsid, the Apical Region of the major capsid protein (VP5) is surface exposed. We investigated whether the VP5 Apical Region contributes to intracellular transport dynamics following entry into primary sensory neurons and also tested the hypothesis that conserved negatively charged amino acids in the Apical Region contribute to VP26 acquisition. To our surprise, neither hypothesis proved true. Instead, mutation of glutamic acid residues in the Apical Region delayed viral propagation and induced focal capsid accumulations in nuclei. Examination of capsid morphogenesis based on epitope unmasking, capsid composition, and ultrastructural analysis indicated that these clusters consisted of procapsids. The results demonstrate that, in addition to established events that occur inside the capsid, the exterior capsid shell promotes capsid morphogenesis and maturation. IMPORTANCE Herpesviruses assemble capsids and encapsidate their genomes by a process that is unlike those of other mammalian viruses but is similar to those of some bacteriophage. Many important aspects of herpesvirus morphogenesis remain enigmatic, including how the capsid shell matures into a stable angularized configuration. Capsid maturation is triggered by activation of a protease that cleaves an internal protein scaffold. We report on the fortuitous discovery that a Region of the major capsid protein that is exposed on the outer surface of the capsid also contributes to capsid maturation, demonstrating that the morphogenesis of the capsid shell from its procapsid precursor to the mature angularized form is dependent upon internal and external components of the megastructure.
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the Apical Region of the herpes simplex virus major capsid protein promotes capsid maturation
bioRxiv, 2018Co-Authors: Laura Lee Ruhge, Alexis Huet, James F Conway, Gregory A SmithAbstract:The herpesvirus capsid assembles in the nucleus as an immature procapsid precursor built around viral scaffold proteins. The event that initiates procapsid maturation is unknown, but it is dependent upon activation of the VP24 internal protease. Scaffold cleavage triggers angularization of the shell and its decoration with the VP26 and pUL25 capsid-surface proteins. In both the procapsid and mature angularized capsid, the Apical Region of the major capsid protein (VP5) is surface exposed. We investigated whether the VP5 Apical Region contributes to intracellular transport dynamics following entry into primary sensory neurons and also tested the hypothesis that conserved negatively-charged amino acids in the Apical Region contribute to VP26 acquisition. To our surprise neither hypothesis proved true. Instead, mutation of glutamic acid residues in the Apical Region delayed viral propagation and induced focal capsid accumulations in nuclei. Examination of capsid morphogenesis based on epitope unmasking, capsid composition, and ultrastructural analysis indicated that these clusters consisted of procapsids. The results demonstrate that, in addition to established events that occur inside the capsid, the exterior capsid shell promotes capsid morphogenesis and maturation.
Marcin Lipowczan - One of the best experts on this subject based on the ideXlab platform.
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a method to determine the displacement velocity field in the Apical Region of the arabidopsis root
Planta, 2012Co-Authors: Jerzy Nakielski, Marcin LipowczanAbstract:In angiosperms, growth of the root apex is determined by the quiescent centre. All tissues of the root proper and the root cap are derived from initial cells that surround this zone. The diversity of cell lineages originated from these initials suggests an interesting variation of the displacement velocity within the root apex. However, little is known about this variation, especially in the most Apical Region including the root cap. This paper shows a method of determination of velocity field for this Region taking the Arabidopsis root apex as example. Assuming the symplastic growth without a rotation around the root axis, the method combines mathematical modelling and two types of empirical data: the published velocity profile along the root axis above the quiescent centre, and dimensions of cell packet originated from the initials of epidermis and lateral root cap. The velocities, calculated for points of the axial section, vary in length and direction. Their length increases with distance from the quiescent centre, in the root cap at least twice slower than in the root proper, if points at similar distance from the quiescent centre are compared. The vector orientation depends on the position of a calculation point, the widest range of angular changes, reaching almost 90°, in the lateral root cap. It is demonstrated how the velocity field is related to both distribution of growth rates and growth-resulted deformation of the cell wall system. Also changes in the field due to cell pattern asymmetry and differences in slope of the velocity profile are modelled.
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a method to determine the displacement velocity field in the Apical Region of the arabidopsis root
Planta, 2012Co-Authors: Jerzy Nakielski, Marcin LipowczanAbstract:In angiosperms, growth of the root apex is determined by the quiescent centre. All tissues of the root proper and the root cap are derived from initial cells that surround this zone. The diversity of cell lineages originated from these initials suggests an interesting variation of the displacement velocity within the root apex. However, little is known about this variation, especially in the most Apical Region including the root cap. This paper shows a method of determination of velocity field for this Region taking the Arabidopsis root apex as example. Assuming the symplastic growth without a rotation around the root axis, the method combines mathematical modelling and two types of empirical data: the published velocity profile along the root axis above the quiescent centre, and dimensions of cell packet originated from the initials of epidermis and lateral root cap. The velocities, calculated for points of the axial section, vary in length and direction. Their length increases with distance from the quiescent centre, in the root cap at least twice slower than in the root proper, if points at similar distance from the quiescent centre are compared. The vector orientation depends on the position of a calculation point, the widest range of angular changes, reaching almost 90°, in the lateral root cap. It is demonstrated how the velocity field is related to both distribution of growth rates and growth-resulted deformation of the cell wall system. Also changes in the field due to cell pattern asymmetry and differences in slope of the velocity profile are modelled. Electronic supplementary material The online version of this article (doi:10.1007/s00425-012-1707-x) contains supplementary material, which is available to authorized users.
Robert E Sharp - One of the best experts on this subject based on the ideXlab platform.
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apoplastic hydrogen peroxide in the growth zone of the maize primary root under water stress i increased levels are specific to the Apical Region of growth maintenance
Journal of Experimental Botany, 2013Co-Authors: Priyamvada Voothuluru, Robert E SharpAbstract:: Previous work on the adaptation of maize (Zea mays L.) primary root growth to water stress showed that cell elongation is maintained in the Apical Region of the growth zone but progressively inhibited further from the apex. Cell wall proteomic analysis suggested that levels of apoplastic reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2), may be modified in a Region-specific manner within the growth zone of water-stressed roots. Apoplastic ROS may have wall loosening or tightening effects and may also have other growth regulatory functions. To gain an understanding of how apoplastic ROS levels change under water stress, cerium chloride staining was used in conjunction with transmission electron microscopy to examine the spatial distribution of apoplastic H2O2. The results revealed that apoplastic H2O2 levels increased specifically in the Apical Region of the growth zone under water stress, correlating spatially with the maintenance of cell elongation. The basal Regions of the growth zone of water-stressed roots and the entire growth zone of well-watered roots exhibited relatively low levels of apoplastic H2O2. The increase in apoplastic H2O2 in the Apical Region under water stress probably resulted, at least in part, from a pronounced increase in oxalate oxidase activity in this Region. By contrast, well-watered roots showed negligible oxalate oxidase activity throughout the growth zone. The results show that changes in apoplastic ROS levels in the root growth zone under water-deficit conditions are regulated in a spatially-specific manner, suggesting that this response may play an important role in maize root adaptation to water stress.
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Genetic variability of oxalate oxidase activity and elongation in water-stressed primary roots of diverse maize and rice lines
Plant Signaling & Behavior, 2013Co-Authors: Priyamvada Voothuluru, Hallie J. Thompson, Sherry Flint-garcia, Robert E SharpAbstract:A previous study of maize primary roots under water stress showed pronounced increases in oxalate oxidase activity and apoplastic hydrogen peroxide in the Apical Region of the growth zone where cell elongation is maintained. We examined whether increased oxalate oxidase activity in water-stressed roots is conserved across diverse lines of maize and rice. The maize lines exhibited varied patterns of activity, with some lines lacking activity in the Apical Region. Moreover, none of the rice lines showed activity in the Apical Region. Also, although the genotypic response of root elongation to water stress was variable in both maize and rice, this was not correlated with the pattern of oxalate oxidase activity. Implications of these findings for root growth regulation under water stress are discussed.
