Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Humans (34)
- Male (33)
- Animals (21)
- Female (21)
- Anti-Mullerian Hormone (18)
-
- 1 - Plant Development & Biomechanics (17)
- Testicular Hormones (17)
- 2 - Phloem Transport & Forisomes (15)
- Child (15)
- *Glycoproteins (14)
- Growth Inhibitors (14)
- Adolescent (13)
- Adult (11)
- Child, Preschool (10)
- Testis (10)
- Infant (9)
- Infant, Newborn (9)
- RNA, Messenger (9)
- Rats (9)
- Ca2+-dependent contractility (8)
- Mullerian Ducts (7)
- Phloem transport (7)
- Aging (6)
- Auxin (6)
- Base Sequence (6)
- Blotting, Northern (6)
- Forisome (6)
- Leydig Cells (6)
- Membrane Proteins (6)
- Mice (6)
- Publication Year
- Publication
-
- Mary M. Lee (45)
- Winfried S. Peters (35)
- Elizabeth J. Luna (8)
- Elisabet Mandon (2)
- Albert-László Barabási (1)
-
- Alisha L. Sarang-Sieminski (1)
- Amit Singh (1)
- Celia A. Schiffer (1)
- Dirk R. Albrecht (1)
- Gyongyi Szabo (1)
- Helen Donis-Keller (1)
- Helen O'Neill (1)
- Hongwei Yu (1)
- Jennifer Kowalski (1)
- Md Mahmudur Rahman (1)
- Nils Henninger (1)
- Philippe T. Georgel (1)
- Sakthikumar Ambady (1)
- Sean P. Ryder (1)
- Stanley D Dunn (1)
- Victor R. Ambros (1)
Articles 91 - 107 of 107
Full-Text Articles in Life Sciences
Atp-Independent Contractile Proteins From Plants, Michael Knoblauch, Gundula Noll, Torsten Müller, Dirk Prüfer, Ingrid Schneider-Hüther, Dörte Scharner, Aart Van Bel, Winfried Peters
Atp-Independent Contractile Proteins From Plants, Michael Knoblauch, Gundula Noll, Torsten Müller, Dirk Prüfer, Ingrid Schneider-Hüther, Dörte Scharner, Aart Van Bel, Winfried Peters
Winfried S. Peters
This paper has no abstract; this is the first paragraph. Emerging technologies are creating increasing interest in smart materials that may serve as actuators in micro- and nanodevices. Mechanically active polymers currently studied include a variety of materials. ATP-driven motor proteins, the actuators of living cells, possess promising characteristics, but their dependence on strictly defined chemical environments can be disadvantagous. Natural proteins that deform reversibly by entropic mechanisms might serve as models for artificial contractile polypeptides with useful functionality, but they are rare. Protein bodies from sieve elements of higher plants provide a novel example. sieve elements form microfluidics systems …
The Biophysics Of Leaf Growth In Salt-Stressed Barley. A Study At The Cell Level., Wieland Fricke, Winfried Peters
The Biophysics Of Leaf Growth In Salt-Stressed Barley. A Study At The Cell Level., Wieland Fricke, Winfried Peters
Winfried S. Peters
Biophysical parameters potentially involved in growth regulation were studied at the single-cell level in the third leaf of barley (Hordeum vulgare) after exposure to various degrees of NaCl stress for 3 to 5 d. Gradients of elongation growth were measured, and turgor pressure, osmolality, and water potentials (ψ) were determined (pressure probe and picoliter osmometry) in epidermal cells of the elongation zone and the mature blade. Cells in the elongation zone adjusted to decreasing external ψ through increases in cell osmolality that were accomplished by increased solute loads and reduced water contents. Cell turgor changed only slightly. In …
Reversible Calcium-Regulated Stopcocks In Legume Sieve Tubes, Michael Knoblauch, Winfried Peters, Katrin Ehlers, Aart Van Bel
Reversible Calcium-Regulated Stopcocks In Legume Sieve Tubes, Michael Knoblauch, Winfried Peters, Katrin Ehlers, Aart Van Bel
Winfried S. Peters
Sieve tubes of legumes (Fabaceae) contain characteristic P-protein crystalloids with controversial function. We studied their behavior by conventional light, electron, and confocal laser scanning microscopy. In situ, crystalloids are able to undergo rapid (<1>sec) and reversible conversions from the condensed resting state into a dispersed state, in which they occlude the sieve tubes. Crystalloid dispersal is triggered by plasma membrane leakage induced by mechanical injury or permeabilizing substances. Similarly, abrupt turgor changes imposed by osmotic shock cause crystalloid dispersal. Because chelators generally prevent the response, divalent cations appear to be the decisive factor in crystalloid expansion. Cycling between dispersal and …
Does Growth Correlate With Turgor-Induced Elastic Strain In Stems? A Re-Evaluation Of De Vries' Classical Experiments, Winfried Peters, Maggie Farm, A. Kopf
Does Growth Correlate With Turgor-Induced Elastic Strain In Stems? A Re-Evaluation Of De Vries' Classical Experiments, Winfried Peters, Maggie Farm, A. Kopf
Winfried S. Peters
The correlation between growth and turgor-induced elastic expansion was studied in hypocotyls of sunflower (Helianthus annuus) seedlings under various growth conditions. Turgor-induced elastic cell wall strain was greater in hypocotyls of faster growing seedlings, i.e. in etiolated versus light-grown ones. It also was higher in rapidly growing young seedlings as compared with nongrowing mature ones. However, analysis of the spatial distribution of elastic strain and growth demonstrated that their correspondence was only apparent. Profiles of elastic strain declined steadily from the top of the hypocotyls toward the basis, whereas the profiles of relative elemental growth rate along the …
The Mechanic State Of “Inner Tissue” In The Growing Zone Of Sunflower Hypocotyls And The Regulation Of Its Growth Rate Following Excision, Winfried Peters, A. Tomos
The Mechanic State Of “Inner Tissue” In The Growing Zone Of Sunflower Hypocotyls And The Regulation Of Its Growth Rate Following Excision, Winfried Peters, A. Tomos
Winfried S. Peters
Spontaneous growth of isolated inner tissue from the etiolated sunflower (Helianthus annuus L.) hypocotyl growing zone was investigated. A new preparation technique allowed measurements starting 3 s after excision. Elongation with respect to the turgescent and plasmolized state was quantified in terms of relative growth rates, facilitating comparison to growth in situ. Turgor and turgor-induced strain were determined. Overall longitudinal strain in inner tissues in situ was positive, indicating that compressive forces exerted by peripheral tissues are outweighed by turgor-dependent tensile stress. Inner tissue expansion following isolation depended on water uptake. Extreme plastic extension rates occurred immediately after excision, …
What Makes Plants Different? Principles Of Extracellular Matrix Function In 'Soft' Plant Tissues [Review Article], Winfried Peters, Wolfgang Hagemann, A. Tomos
What Makes Plants Different? Principles Of Extracellular Matrix Function In 'Soft' Plant Tissues [Review Article], Winfried Peters, Wolfgang Hagemann, A. Tomos
Winfried S. Peters
An overview of the biomechanic and morphogenetic function of the plant extracellular matrix (ECM) in its primary state is given. ECMs can play a pivotal role in cellular osmo- and volume-regulation, if they enclose the cell hermetically and constrain hydrostatic pressure evoked by osmotic gradients between the cell and its environment. From an engineering viewpoint, such cell walls turn cells into hydraulic machines, which establishes a crucial functional differences between cell walls and other cellular surface structures. Examples of such hydraulic machineries are discussed. The function of cell walls in the control of pressure, volume, and shape establishes constructional evolutionary …
The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle
The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle
Winfried S. Peters
High-resolution profiles of surface pH and growth along vertically growing maize (Zea mays) primary root tips were determined simultaneously by pH-sensitive microelectrodes and marking experiments. Methodological tests were carried out that proved the reliability of our kinematic growth analysis, while questioning the validity of an alternative technique employed previously. A distal acidic zone around the meristematic region and a proximal one around the elongation zone proper were detected. This pattern as such persisted irrespective of the bulk pH value. The proximal acidic region coincided with maximum relative elemental growth rates (REGR), and both characters reacted in a correlated …
Xet-Related Genes And Growth Kinematics In Barley Leaves, Winfried Peters, Wieland Fricke, Peter Chandler
Xet-Related Genes And Growth Kinematics In Barley Leaves, Winfried Peters, Wieland Fricke, Peter Chandler
Winfried S. Peters
Recently Schünmann et al. (1997; Plant, Cell and Environment 20, 1439–1450) investigated the correlation of spatial patterns of xyloglucan-endotransglycosylase (XET) activity, XET-related mRNAs, and growth in elongating barley (Hordeum vulgare L.) leaves. Here, methodological difficulties in the kinematic growth analysis are discussed, and it is concluded that the role that XET-related gene activity plays in the control of spatial growth patterns remains undetermined.
The Temporal Correlation Of Changes In Apoplast Ph And Growth Rate In Maize Coleoptile Segments, Winfried Peters, Hartwig Lüthen, Michael Böttger, Hubert Felle
The Temporal Correlation Of Changes In Apoplast Ph And Growth Rate In Maize Coleoptile Segments, Winfried Peters, Hartwig Lüthen, Michael Böttger, Hubert Felle
Winfried S. Peters
Auxin induces extracellular acidification in growing shoot tissue. The causal relationship between this process and auxin-mediated growth is debated, partly because of contradicting previous reports on the temporal correlation of auxin-induced apoplast pH-drops and growth bursts. We have simultaneously measured both parameters on the background of spontaneously occurring endogenous changes in growth rate and apoplast pH in maize coleoptile segments. Our data demonstrate good temporal correlation, during both the ‘Spontaneous Growth Response’ and the response to exogenous auxin, which is transient under the conditions chosen due to rapid auxin metabolism. We suggest that cell wall pH and growth rate are …
Wounding-Induced Cell Wall Ph Shifts In Coleoptile Segments Of Various Poaceae, Winfried Peters
Wounding-Induced Cell Wall Ph Shifts In Coleoptile Segments Of Various Poaceae, Winfried Peters
Winfried S. Peters
Wounding-induced extracellular pH shifts were characterized previously in excised segments of maize (Zea mays L.) coleoptiles. In the present study it is demonstrated that similar pH shifts also occur in Triticum aestivum L., Secale cereale L., Hordeum vulgare L., Avena sativa L., Sorghum durra (Forsk.) Stapf, and Setaria italica (L.) Beauv., with characteristic quantitative differences between the species. Indole-acetic acid induces pronounced drops of the medium pH in all species except Setaria italica.
Iaa Breakdown And Its Effect On Auxin-Induced Cell Wall Acidification In Maize Coleoptile Segments, Winfried Peters, Christa Lommel, Hubert Felle
Iaa Breakdown And Its Effect On Auxin-Induced Cell Wall Acidification In Maize Coleoptile Segments, Winfried Peters, Christa Lommel, Hubert Felle
Winfried S. Peters
In excised Zea mays L. coleoptiles incubated in aerated media at high fresh weight per volume ratios, indole-3-acetic acid induces transient drops of extracellular pH. Based on the quantitative dependency of the response on the initial auxin concentration we developed a novel auxin bioassay, which allows reliable estimation of IAA concentrations between 10−8.5 and 10−5 M. Using the bioassay and complementary concentration measurements by IAA fluorescence we found the transient IAA-induced pH response paralleled by a decrease of auxin activity and concentration in the medium. This decline is rapid and starts immediately upon auxin addition, and insofar differs from the …
The Determination Of Relative Elemental Growth Rate Profiles From Segmental Growth Rates (A Methodological Evaluation), Winfried Peters, Nirit Bernstein
The Determination Of Relative Elemental Growth Rate Profiles From Segmental Growth Rates (A Methodological Evaluation), Winfried Peters, Nirit Bernstein
Winfried S. Peters
Relative elemental growth rate (REGR) profiles describe spatial patterns of growth intensity; they are indispensable for causal growth analyses. Published methods of REGR profile determination from marking experiments fall in two classes: the profile is either described by a series of segmental growth rates, or calculated as the slope of a function describing the displacement velocities of points along the organ. The latter technique is usually considered superior for theoretical reasons, but to our knowledge, no comparative methodological study of the two approaches is currently available. We formulated a model REGR profile that resembles those reported from primary roots. We …
The Epidermis Still In Control?, Winfried Peters, A. Tomos
The Epidermis Still In Control?, Winfried Peters, A. Tomos
Winfried S. Peters
This paper has no abstract; these are the first two paragraphs. The search for a molecular mechanism of auxin action has rendered the “Auxin-Binding-Protein 1” (ABP-1) the top candidate for a functional auxin receptor (Venis and Napier, 1995), although its status remains disputed (Jones, 1994; Hertel, 1995; Napier, 1995; Venis, 1995). ABP-1 had long been thought to be localized exclusively in epidermal cells in coleoptiles (Löbler and Klämbt, 1985), and thus had fitted nicely the “epidermal-growth-control-hypothesis” (Kutschera, 1987, 1992). The recent report from the same lab of its uniform distribution throughout the coleoptile (Kayser and Klämbt, 1995) not only rises …
The History Of Tissue Tension, Winfried S. Peters, A. Deri Tomos
The History Of Tissue Tension, Winfried S. Peters, A. Deri Tomos
Winfried S. Peters
In recent years the phenomenon of tissue tension and its functional connection to elongation growth has regained much interest. In the present study we reconstruct older models of mechanical inhomogenities in growing plant organs, in order to establish an accurate historical background for the current discussion. We focus on the iatromechanic model developed in Stephen Hales' Vegetable Staticks, Wilhelm Hofmeister's mechanical model of negative geotropism, Julius Sachs' explanation of the development of tissue tension, and the differential-auxin-response-hypothesis by Kenneth Thimann and Charles Schneider. Each of these models is considered in the context of its respective historic and theoretical environment. …
Pollination Of The Crown Imperial Fritillaria Imperialis By Great Tits Parus Major, Winfried S. Peters, Michael Pirl, Gerhard Gottsberger, Dieter Stefan Peters
Pollination Of The Crown Imperial Fritillaria Imperialis By Great Tits Parus Major, Winfried S. Peters, Michael Pirl, Gerhard Gottsberger, Dieter Stefan Peters
Winfried S. Peters
Visitations of flowers of the Crown Imperial by Great Tits at two different locations in Hessen, Germany, in 1990 and 1993 are described. The observations prove that flowers were visited because of the nectar; most likely pollination occurs during this visits. Similar reports from Europe are discussed. The significance of specific interactions including ecological generalists such as the Great Tit is considered in the context of the phylogenetic reconstruction of the development of co-adaptive syndroms.
Auxin-Induced H+-Pump Stimulation Does Not Depend On The Presence Of Epidermal Cells In Corn Coleoptiles, Winfried Peters, Ursula Richter, Hubert Felle
Auxin-Induced H+-Pump Stimulation Does Not Depend On The Presence Of Epidermal Cells In Corn Coleoptiles, Winfried Peters, Ursula Richter, Hubert Felle
Winfried S. Peters
Cell-wall acidification and electrical reactions (depolarization and hyperpolarization) are typical auxin responses in maize (Zea mays L.) coleoptiles. In an attempt to test the role of the outer epidermis in these responses, they have been measured and compared in intact and peeled coleoptile fragments. To exclude interactions between parenchymal and epidermal cells, the coleoptile pieces were completely stripped of their outer epidermis. This preparation was monitored by means of a scanning electron microscope. When externally applied indole-3-acetic acid was tested, we found that neither cell-wall acidification nor the electrical membrane responses depended on the presence of intact epidermal cells.
The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme
The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme
Winfried S. Peters
The electrical response of Zea mays coleoptiles and suspension cultured cells to several growth-promoting auxins (IAA, IBA, 2,4-D, 2,4,5-T, 1-NAA) and some of their structural analogues (2,3-D, 2-NAA) has been tested. In coleoptiles two typical electrical responses to IAA are observed: an immediate rapid depolarization, and a hyperpolarization following 7–10 minutes after the first external addition of IAA. Of the other tested compounds only 1-NAA significantly depolarized the cells, whereas all auxins as well as the analogues evoked delayed hyperpolarizations. In contrast, the suspension cells were not hyperpolarized by any of the tested compounds, but were strongly depolarized by IAA, …