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Daniel J. Cosgrove - One of the best experts on this subject based on the ideXlab platform.
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loosening of plant Cell walls by expansins
Nature, 2000Co-Authors: Daniel J. CosgroveAbstract:Plant Cell walls are the starting materials for many commercial products, from lumber, paper and textiles to thickeners, films and explosives. The Cell wall is secreted by each Cell in the plant body, forming a thin fibreglass-like network with remarkable strength and flexibility. During growth, plant Cells secrete a protein called expansin, which unlocks the network of wall polysaccharides, permitting turgor-driven Cell Enlargement. Germinating grass pollen also secretes an unusual expansin that loosens maternal Cell walls to aid penetration of the stigma by the pollen tube. Expansin's action has puzzling implications for plant Cell-wall structure. The recent explosion of gene sequences and expression data has given new hints of additional biological functions for expansins.
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relaxation in a high stress environment the molecular bases of extensible Cell walls and Cell Enlargement
The Plant Cell, 1997Co-Authors: Daniel J. CosgroveAbstract:SUMMARY AND PERSPECTIVE The Enlargement of plant Cells involves the coordinate con- trol of wall synthesis and expansion, solute and water trans- port, membrane synthesis, Golgi secretion, ion transport, and many other processes. In this review, I have focused on the wall because it is the major control point for Cell enlarge- ment. Some of the key processes that may be involved in wall Enlargement are summarized in Figure 4. I offer the following speculative picture as a tentative working model for the control of wall expansion. The primary wall is initially secreted and assembled in a form that is me- chanically tough yet has “hot spots” where expansin can weaken microfibril-matrix adhesion. Expansin activity, which is modulated both by secretion of the protein to the wall and by changes in the pH and redox potential of the wall, in- duces the stress relaxation and polymer creep needed for wall Enlargement and water uptake by the Cell. By altering Synthesis & secretion secretion of wall polysaccharides and proteins
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Plant Cell Enlargement and the action of expansins
BioEssays : news and reviews in molecular cellular and developmental biology, 1996Co-Authors: Daniel J. CosgroveAbstract:Plant Cells are caged within a distended polymeric network (the Cell wall), which enlarges by a process of stress relaxation and slippage (creep) of the polysaccharides that make up the load-bearing network of the wall. Protein mediators of wall creep have recently been isolated and characterized. These proteins, called expansins, appear to disrupt the noncovalent adhesion of matrix polysaccharides to Cellulose microfibrils, thereby permitting turgor-driven wall Enlargement. Expansin activity is specifically expressed in the growing tissues of dicotyledons and monocotyledons. Sequence analysis of cDNAs indicates that expansins are novel proteins, without previously known functional motifs. Comparison of expansin cDNAs from cucumber, pea, Arabidopsis and rice shows that the proteins are highly conserved in size and amino acid sequence. Phylogenetic analysis of expansin sequences suggests that this multigene family diverged before the evolution of angiosperms. Speculation is presented about the role of this gene family in plant development and evolution.
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Disruption of hydrogen bonding between plant Cell wall polymers by proteins that induce wall extension.
Proceedings of the National Academy of Sciences, 1994Co-Authors: S. Mcqueen-mason, Daniel J. CosgroveAbstract:Plant Cell Enlargement is controlled by the ability of the constraining Cell wall to expand. This ability has been postulated to be under the control of polysaccharide hydrolases or transferases that weaken or rearrange the loadbearing polymeric networks in the wall. We recently identified a family of wall proteins, called expansins, that catalyze the extension of isolated plant Cell walls. Here we report that these proteins mechanically weaken pure Cellulose paper in extension assays and stress relaxation assays, without detectable Cellulase activity (exo- or endo- type). Because paper derives its mechanical strength from hydrogen bonding between Cellulose microfibrils, we conclude that expansins can disrupt hydrogen bonding between Cellulose fibers. This conclusion is further supported by experiments in which expansin-mediated wall extension (i) was increased by 2 M urea (which should weaken hydrogen bonding between wall polymers) and (ii) was decreased by replacement of water with deuterated water, which has a stronger hydrogen bond. The temperature sensitivity of expansin-mediated wall extension suggests that units of 3 or 4 hydrogen bonds are broken by the action of expansins. In the growing Cell wall, expansin action is likely to catalyze slippage between Cellulose microfibrils and the polysaccharide matrix, and thereby catalyze wall stress relaxation, followed by wall surface expansion and plant Cell Enlargement.
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role of expansin in Cell Enlargement of oat coleoptiles analysis of developmental gradients and photocontrol
Plant Physiology, 1993Co-Authors: Daniel J. CosgroveAbstract:Expansins are wall proteins that mediate a type of acid-induced extension in isolated plant Cell walls (S. McQueen-Mason, D.M. Durachko, D.J. Cosgrove [1992] Plant Cell 4: 1425-1433). To assess the role of these proteins in the process of Cell Enlargement in living tissues, we compared the spatial and temporal growth patterns of oat (Avena sativa L.) coleoptiles with four wall properties related to expansin action. These properties were (a) the ability of isolated walls and living segments to extend in acidic buffer, (b) the ability of heat-inactivated walls to extend upon application of expansins, (c) the amount of immunologically detectable expansin in wall protein extracts, and (d) the extractable expansin activity of walls. Growth rate was maximal in the apical half of dark-grown coleoptiles and negligible in the basal region. This growth pattern correlated with properties a and b; in contrast, the amount and activity of extractable expansin (properties c and d) were reduced only in the most basal region. Upon exposure to white light, coleoptiles abruptly ceased elongation at 8 to 10 h after start of irradiation, and this cessation correlated with reductions in properties a to c. The growth cessation at 8 to 10 h also coincided with the loss of growth response to exogenous auxin and fusicoccin in excised coleoptile segments. These results lend correlative support to the hypothesis that expansin action is important for growth responses of living oat coleoptiles (e.g. responses to acidic buffers, auxin, fusicoccin, aging, and light). Our results suggest that changes in the susceptibility of the wall to expansin action, rather than changes in expansin activity, may be a key determinant of the growth patterns in oat coleoptiles.
Yukihide Iwamoto - One of the best experts on this subject based on the ideXlab platform.
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bone marrow fat Cell Enlargement in early steroid induced osteonecrosis a histomorphometric study of autopsy cases
Pathology Research and Practice, 2005Co-Authors: Goro Motomura, Keita Miyanishi, Takuaki Yamamoto, Akihisa Yamashita, Katsuo Sueishi, Yukihide IwamotoAbstract:Some animal studies and magnetic resonance imaging studies suggest that there may exist a relationship between abnormal lipid metabolisms and osteonecrosis. The purpose of this study was to examine the size of bone marrow fat Cells in the early osteonecrosis femoral head using autopsy specimens. We compared the size of bone marrow fat Cells in the viable areas in the following three autopsy groups: the early osteonecrosis group (4 femoral heads); the steroid-administered group (without osteonecrosis) (n = 10), and the normal group (n = 19). In addition, after adjusting for age and sex, the size of bone marrow fat Cells was compared using multiple regression analysis. The size of bone marrow fat Cells was significantly larger in the early osteonecrosis group (84.7+/-5.5 microm) than in both the steroid-administered group (75.3+/-4.3 microm) and the normal group (76.3+/-4.9 microm) (p<0.01 and p<0.05, respectively). After adjusting for age and sex, the size of bone marrow fat Cells in the early osteonecrosis group was significantly larger as compared with the other groups. This study suggests that in steroid-induced osteonecrosis, the size of bone marrow fat Cells increases significantly at an early stage.
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bone marrow fat Cell Enlargement and a rise in intraosseous pressure in steroid treated rabbits with osteonecrosis
Bone, 2002Co-Authors: Keita Miyanishi, Takuaki Yamamoto, Takahiko Irisa, Akihisa Yamashita, Seiya Jingushi, Yasuo Noguchi, Yukihide IwamotoAbstract:The etiology of steroid-induced osteonecrosis (ON) is unclear. This study was designed to determine whether bone marrow fat Cell size, intraosseous pressure, and blood flow rate differed between steroid-treated rabbits with ON and those without. Twenty-nine rabbits were intramuscularly injected once with 20 mg/kg of methylprednisolone acetate (MPSL), and five rabbits were injected once with physiologic saline (PS) as a control. Intraosseous pressure and blood flow rate in the proximal femur were determined before and at 2 weeks after the injection. After these measurements, both femora and humeri were histopathologically examined for the presence of ON, and size of bone marrow fat Cells were morphologically examined. At 2 weeks after steroid injection, the intraosseous pressure was significantly higher in rabbits with ON than in those without (p = 0.0251), and the blood flow rate had decreased significantly more in rabbits with ON than in those without (p = 0.0051). The size of the bone marrow fat Cells was significantly (p = 0.0004) larger in rabbits with ON (diameter, 63.5 +/- 5.8 microm) than in those without (diameter, 53.3 +/- 6.9 microm). Injection of PS (5 rabbits), 1 (10 rabbits), 5 (10 rabbits), and 20 (10 rabbits) mg/kg of body weight of MPSL showed that a larger dose of steroid increased both fat Cell size and prevalence of ON. These results suggest that bone marrow fat Cell Enlargement and a rise in intraosseous pressure may be important when considering the pathophysiology of steroid-induced ON in rabbits.
James D Morre - One of the best experts on this subject based on the ideXlab platform.
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role in the Enlargement phase of Cell growth
2012Co-Authors: James D Morre, Dorothy M. MorréAbstract:Cell Enlargement is a necessary requisite for sustained growth of Cells of all higher organisms. Close coupling of plasma membrane electron transport and growth was indicated from the beginning with the earliest investigations. The mechanistic basis for the correlation became apparent with the discovery of a protein disulfide–thiol interchange activity associated with the ENOX proteins. Rates of Cell Enlargement and rates of ENOX1 and ENOX2 activities in response to activators, inhibitors, anticancer drugs or overexpression are highly correlated. Additionally, rates of Cell Enlargement are periodic with major period lengths paralleling those of the ENOX proteins present. Both Cell Enlargement and ENOX activity are blocked by thiol reagents. Furthermore, Cell Enlargement is restricted to the protein disulfide–thiol interchange part of the ENOX cycle that alternates with the oxidative (NADH or hydroquinone) portion of the cycle. Recombinant ENOX proteins when incorporated into synthetic lipid vesicles with other required constituents (AAA-ATPase, ATP, defined thiol-rich protein source) recapitulate Cell Enlargement in a completely Cell-free system. Implicit in these findings is that the mechanism of Cell Enlargement in both plants and animals is similar and an active process not obligatorily driven by biosynthesis or turgor. An energy requirement is universal and met at the Cell surface through coupling with a plasma membrane p97 AAA-ATPase (ATPase Associated with Diverse Cellular Activities).
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cho Cell Enlargement oscillates with a temperature compensated period of 24 min
Biochimica et Biophysica Acta, 2000Co-Authors: Rhea Pogue, Dorothy M. Morré, James D MorreAbstract:The rate of increase in Cell area of CHO Cells when measured at intervals of 1 min using a light microscope equipped with a video measurement system, oscillated with a minimum period of about 24 min. The pattern of oscillations paralleled those of the 24 min period observed with the oxidation of NADH by an external Cell surface or plasma membrane NADH oxidase. The increase in Cell area was non-linear. Intervals of rapid increase in area alternated with intervals of rapid decrease in area. The length of the 24 min period was temperature-compensated (approximately the same when measured at 14 degrees C, 24 degrees C or 34 degrees C) while the rate of Cell Enlargement increased with temperature over this same range of temperatures.
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glaucarubolone and simalikalactone d respectively preferentially inhibit auxin induced and constitutive components of plant Cell Enlargement and the plasma membrane nadh oxidase
International Journal of Plant Sciences, 1999Co-Authors: James D Morre, Paul A GriecoAbstract:Glaucarubolone, a naturally occurring quassinoid from the root bark of Castela polyandra, Simaroubaceae, with a C(8), C(11) hemiacetal bridge, is demonstrated to be a potent inhibitor of both the auxin‐induced component of the plasma membrane NADH oxidase and of plant Cell Enlargement in soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), tomato (Lycopersicum esculentum), and Sorghum (Sorghum vulgare). Auxin‐stimulated NADH oxidase activity of isolated vesicles of soybean, A. thaliana, and tomato plasma membranes were inhibited half maximally by ca. 0.1 nM glaucarubolone. Auxin‐induced Enlargement of stem segments of soybean and elongation growth of A. thaliana seedlings were inhibited half maximally by ca. 10 nM glaucarubolone with significant inhibition of auxin‐stimulated growth even at nannomolar glaucarubolone concentrations. Seedlings of A. thaliana and tomato treated with sublethal concentrations of 1–10 μM glaucarubolone remained alive but failed to elongate for periods of two to several mo...
Dorothy M. Morré - One of the best experts on this subject based on the ideXlab platform.
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role in the Enlargement phase of Cell growth
2012Co-Authors: James D Morre, Dorothy M. MorréAbstract:Cell Enlargement is a necessary requisite for sustained growth of Cells of all higher organisms. Close coupling of plasma membrane electron transport and growth was indicated from the beginning with the earliest investigations. The mechanistic basis for the correlation became apparent with the discovery of a protein disulfide–thiol interchange activity associated with the ENOX proteins. Rates of Cell Enlargement and rates of ENOX1 and ENOX2 activities in response to activators, inhibitors, anticancer drugs or overexpression are highly correlated. Additionally, rates of Cell Enlargement are periodic with major period lengths paralleling those of the ENOX proteins present. Both Cell Enlargement and ENOX activity are blocked by thiol reagents. Furthermore, Cell Enlargement is restricted to the protein disulfide–thiol interchange part of the ENOX cycle that alternates with the oxidative (NADH or hydroquinone) portion of the cycle. Recombinant ENOX proteins when incorporated into synthetic lipid vesicles with other required constituents (AAA-ATPase, ATP, defined thiol-rich protein source) recapitulate Cell Enlargement in a completely Cell-free system. Implicit in these findings is that the mechanism of Cell Enlargement in both plants and animals is similar and an active process not obligatorily driven by biosynthesis or turgor. An energy requirement is universal and met at the Cell surface through coupling with a plasma membrane p97 AAA-ATPase (ATPase Associated with Diverse Cellular Activities).
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Cell Enlargement of plant tissue explants oscillates with a temperature-compensated period length of CA. 24 min
In Vitro Cellular & Developmental Biology - Plant, 2002Co-Authors: D. James Morre, Philipp Ternes, Dorothy M. MorréAbstract:Rate of plant Cell Enlargement, measured at intervals of 3 min using a sensitive linear transducer, oscillates with a minimum period of about 24 min that parallels the 24-min periodicity observed with the oxidation of NADH by the external plasma membrane NADH oxidase and of single Cells measured previously by video-enhanced light microscopy. Also exhibiting 24-min oscillations is the steady-state rate of Cell Enlargement induced by the addition of the auxin herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) or the natural auxin indole-3-acetic acid (IAA). Immediately following 2,4-D addition, a very complex pattern of oscillations is frequently observed. However, after several hours a dominant 24-min period emerges. The length of the 24 min period is temperature compensated and remains constant at 24 min when measured at 15, 25 or 35°C, despite the fact that the rate of Cell Enlargement approximately doubles for each 10°C rise over this same range of temperatures.
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soybean Cell Enlargement oscillates with a temperature compensated period length of ca 24 min
In Vitro Cellular & Developmental Biology – Plant, 2001Co-Authors: D. James Morre, Rhea Pogue, Dorothy M. MorréAbstract:Rate of Enlargement of epidermal Cells from soybean, when measured at intervals of 1 min using a light microscope equipped with a video measurement system, oscillated with a period length of about 24 min. This oscillation parallels the 24-min periodicity observed for the oxidation of NADH by the external plasma membrane NADH oxidase. The increase in length was not only non-linear, but intervals of rapid increase in area alternated with intervals of rapid decrease in area. The length of the period was temperature compensated, and was approximately the same when measured at 14, 24 and 34 degrees C even though the rate of Cell Enlargement varied over this same range of temperatures. These observations represent the first demonstration of an oscillatory growth behavior correlated with a biochemical activity where the period length of both is independent of temperature (temperature compensated) as is the hallmark of clock-related biological phenomena.
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cho Cell Enlargement oscillates with a temperature compensated period of 24 min
Biochimica et Biophysica Acta, 2000Co-Authors: Rhea Pogue, Dorothy M. Morré, James D MorreAbstract:The rate of increase in Cell area of CHO Cells when measured at intervals of 1 min using a light microscope equipped with a video measurement system, oscillated with a minimum period of about 24 min. The pattern of oscillations paralleled those of the 24 min period observed with the oxidation of NADH by an external Cell surface or plasma membrane NADH oxidase. The increase in Cell area was non-linear. Intervals of rapid increase in area alternated with intervals of rapid decrease in area. The length of the 24 min period was temperature-compensated (approximately the same when measured at 14 degrees C, 24 degrees C or 34 degrees C) while the rate of Cell Enlargement increased with temperature over this same range of temperatures.
John M Russell - One of the best experts on this subject based on the ideXlab platform.
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the sodium potassium chloride cotransporter human cytomegalovirus and the Cell cycle
Physiology and Pathology of Chloride Transporters and Channels in the Nervous System#R##N#From Molecules to Diseases, 2009Co-Authors: John M RussellAbstract:This chapter defines the basics and pathology of human cytomegalovirus (HCMV) infection. HCMV infection is widespread, affecting 50–90% of the adult population. It has the potential to be deadly under certain conditions. The most obvious morphological characteristic of infection with this pathogen is Cell swelling, termed cytomegaly, a 2–3-fold Enlargement of the host Cell. It is this Cell Enlargement feature that led to the original interest in the possible role of NKCC in the HCMV infection cycle. The virus is spread by contact with body fluids such as blood, saliva, semen, tears, breast milk and vaginal secretions. HCMV, a beta-herpes virus, is an opportunistic virus like other members of the Herpes family. Following the primary infection, it remains latent, hidden in Cells of the salivary glands, kidneys, bone Cells as well as in blood Cells such as lymphocytes and macrophages.
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human cytomegalovirus induced host Cell Enlargement is iron dependent
American Journal of Physiology-cell Physiology, 2004Co-Authors: William E Crowe, Lilia M Maglova, Prem Ponka, John M RussellAbstract:A hallmark of human cytomegalovirus (HCMV) infection is the characteristic Enlargement of the host Cells (i.e., cytomegaly). Because iron (Fe) is required for Cell growth and Fe chelators inhibit v...