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101.
Plant diversity shapes microbe‐rhizosphere effects on P mobilisation from organic matter in soil
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Nina Hacker Anne Ebeling Arthur Gessler Gerd Gleixner Odette González Macé Hans de Kroon Markus Lange Liesje Mommer Nico Eisenhauer Janneke Ravenek Stefan Scheu Alexandra Weigelt Cameron Wagg Wolfgang Wilcke Yvonne Oelmann 《Ecology letters》2015,18(12):1356-1365
Plant species richness (PSR) increases nutrient uptake which depletes bioavailable nutrient pools in soil. No such relationship between plant uptake and availability in soil was found for phosphorus (P). We explored PSR effects on P mobilisation [phosphatase activity (PA)] in soil. PA increased with PSR. The positive PSR effect was not solely due to an increase in Corg concentrations because PSR remained significant if related to PA:Corg. An increase in PA per unit Corg increases the probability of the temporal and spatial match between substrate, enzyme and microorganism potentially serving as an adaption to competition. Carbon use efficiency of microorganisms (Cmic:Corg) increased with increasing PSR while enzyme exudation efficiency (PA:Cmic) remained constant. These findings suggest the need for efficient C rather than P cycling underlying the relationship between PSR and PA. Our results indicate that the coupling between C and P cycling in soil becomes tighter with increasing PSR. 相似文献
102.
103.
Matthew P Johnson Anthony PR Brain Alexander V Ruban 《Plant signaling & behavior》2011,6(9):1386-1390
Using freeze-fracture electron microscopy we have recently shown that non-photochemical quenching (NPQ), a mechanism of photoprotective energy dissipation in higher plant chloroplasts, involves a reorganization of the pigment-protein complexes within the stacked grana thylakoids.1 Photosystem II light harvesting complexes (LHCII) are reorganized in response to the amplitude of the light driven transmembrane proton gradient (ΔpH) leading to their dissociation from photosystem II reaction centers and their aggregation within the membrane.1 This reorganization of the PSII-LHCII macrostructure was found to be enhanced by the formation of zeaxanthin and was associated with changes in the mobility of the pigment-protein complexes therein.1 We suspected that the structural changes we observed were linked to the ΔpH-induced changes in thylakoid membrane thickness that were first observed by Murikami and Packer.2,3 Here using thin-section electron microscopy we show that the changes in thylakoid membrane thickness do not correlate with ΔpH per se but rather the amplitude of NPQ and is thus affected by the de-epoxidation of the LHCII bound xanthophyll violaxanthin to zeaxanthin. We thus suggest that the change in thylakoid membrane thickness occurring during NPQ reflects the conformational change within LHCII proteins brought about by their protonation and aggregation within the membrane.Key words: nonphotochemical quenching, photoprotection, LHCII, photosystem II, thylakoid membrane 相似文献
104.
Understanding plant response to wind is complicated as this factor entails not only mechanical stress, but also affects leaf microclimate. In a recent study, we found that plant responses to mechanical stress (MS) may be different and even in the opposite direction to those of wind. MS-treated Plantago major plants produced thinner more elongated leaves while those in wind did the opposite. The latter can be associated with the drying effect of wind as is further supported by data on petiole anatomy presented here. These results indicate that plant responses to wind will depend on the extent of water stress. It should also be recognized that the responses to wind may differ between different parts of a plant and between plant species. Physiological research on wind responses should thus focus on the signal sensing and transduction of both the mechanical and drought signals associated with wind, and consider both plant size and architecture.Key words: biomechanics, leaf anatomy, phenotypic plasticity, plant architecture, signal transduction thigmomorphogenesis, windWind is one of the most ubiquitous environmental stresses, and can strongly affect development, growth and reproductive yield in terrestrial plants.1–3 In spite of more than two centuries of research,4 plant responses to wind and their underlying mechanisms remain poorly understood. This is because plant responses to mechanical movement themselves are complicated and also because wind entails not only mechanical effects, but also changes in leaf gas and heat exchange.5–7 Much research on wind has focused primarily on its mechanical effect. Notably, several studies that determine plant responses to mechanical treatments such as flexing, implicitly extrapolate their results to wind effects.8–10 Our recent study11 showed that this may lead to errors as responses to wind and mechanical stimuli (in our case brushing) can be different and even in the opposite direction. In this paper, we first separately discuss plant responses to mechanical stimuli, and other wind-associated effects, and then discuss future challenges for the understanding of plant responses to wind.It is often believed that responses to mechanical stress (thigmomorphogenesis) entail the production of thicker and stronger plant structures that resist larger forces. This may be true for continuous unidirectional forces such as gravity, however for variable external forces (such as wind loading or periodic flooding) avoiding such mechanical stress by flexible and easily reconfigurable structures can be an alternative strategy.12–14 How plants adapt or acclimate to such variable external forces depends on the intensity and frequency of stress and also on plant structures. Reduced height growth is the most common response to mechanical stimuli.15,16 This is partly because such short stature increases the ability of plants to both resist forces (e.g., real-locating biomass for radial growth rather than elongation growth), and because small plants experience smaller drag forces (Fig. 1). Some plant species show a resistance strategy in response to mechanical stress by increasing stem thickness1,10 and tissue strength.7 But other species show an avoidance strategy by a reduction in stem or petiole thickness and flexural rigidity in response to MS.11,15–18 These different strategies might be associated with plant size and structure. Stems of larger plants such as trees and tall herbs are restricted in the ability to bend as they carry heavy loads7,10,19 (Fig. 1). Conversely short plants are less restricted in this respect and may also be prone to trampling for which stress-avoidance would be the only viable strategy.18,20 Systematic understanding of these various responses to mechanical stress remains to be achieved.Open in a separate windowFigure 1A graphical representation of how wind effects can be considered to entail both a drying and a mechanical effect. Adaptation or acclimation to the latter can be through a force resistance strategy or a force avoidance strategy, the benefit of which may depend on the size and architecture of plants as well as the location of a given structure within a plant.Wind often enhances water stress by reducing leaf boundary layers and reduces plant temperature by transpiration cooling. The latter effect may be minor,11 but the former could significantly affect plant development. Anten et al. (2010) compared phenotypic traits and growth of Plantago major that was grown under mechanical stimuli by brushing (MS) and wind in the factorial design. Both MS and wind treatments reduced growth and influenced allocation in a similar manner. MS plants, however, had more slender petioles and narrower leaf blades while wind exposed plants exhibited the opposite response having shorter and relatively thicker petioles and more round-shaped leaf blades. MS plants appeared to exhibit stress avoidance strategy while such responses could be compensated or overridden by water stress in wind exposure.11 A further analysis of leaf petiole anatomy (Fig. 2) supports this view. The vascular fraction in the petiole cross-section was increased by wind but not by MS, suggesting that higher water transport was required under wind. Our results suggest that drying effect of wind can at least to some extent override its mechanical effect.Open in a separate windowFigure 2Representative images of petiole cross-sections of Plantago major grown in 45 days in continuous wind and/or mechanical stimuli (A–D). Petiole cross-section area (E) and vascular bundle fraction in the cross-section of petiole (F). mean + SD (n = 12) are shown. Significance levels of ANOVA; ***p < 0.001, **p < 0.01, *p < 0.05, ns p > 0.05.Physiological knowledge on plant mechanoreception and signal transduction has been greatly increased during the last decades. Plants sense mechanical stimuli through membrane strain with stretch activated channels21 and/or through some linker molecules connecting the cell wall, plasma membrane and cytoskeleton.4,22,23 This leads to a ubiquitous increase in intracellular Ca2+ concentration. The increased Ca2+ concentration is sensed by touch induced genes (TCHs),24,25 which activates downstream transduction machineries including a range of signaling molecules and phytohormones, consequently altering physiological and developmental processes.26 Extending this knowledge to understand plant phenotypic responses to wind however remains a challenge. As responses to wind have been found to differ among parts of a plant (e.g., terminal vs. basal stem) and also across species, physiological studies should be extended to the whole-plant as integrated system rather than focusing on specific tissue level. Furthermore to understand the general mechanism across species, it is required to study different species from different environmental conditions. Advances in bioinformatics, molecular and physiological research will facilitate cross-disciplinary studies to disentangle the complicated responses of plants to wind. 相似文献
105.
106.
Bläsche R Ebeling G Perike S Weinhold K Kasper M Barth K 《The international journal of biochemistry & cell biology》2012,44(3):514-524
Changes in intracellular calcium concentration [Ca(2+)](i) are believed to influence the proliferation and differentiation of airway epithelial cells both in vivo and in vitro. In the present study, using mouse alveolar epithelial E10 cells, we demonstrated that the treatment of lung epithelial cells with BLM resulted in elevated intracellular Ca(2+) levels. BLM further increased P2rx7 mRNA expression and P2X7R protein levels, paralleled by increased PKC-β1 levels. BLM treatment or stimulation of the P2X7R with the P2X7R agonist BzATP induced translocation of PKC-β1 from the cytoplasm to the membrane. The expression of PKC-β1 was repressed by the P2X7R inhibitor oxATP, suggesting that PKC-β1 is downstream of P2X7R activation. Furthermore, cells exposed to BLM contained increased amounts of P2X7R and PKC-β1 in Cav-1 containing lipid raft fractions. The comparison of lung tissues from wild-type and P2rx7(-/-) mice revealed decreased protein and mRNA levels of PKC-β1 and CaM as well as decreased immunoreactivity for PKC-β1. The knockdown of P2X7R in alveolar epithelial cells resulted also in a loss of PKC-β1. These data suggest that the effect of P2X7R on expression of PKC-β1 detected in alveolar epithelial cells is also functioning in the animal model. Immunohistochemical evaluation of fibrotic lungs derived from a BLM-induced mouse model revealed a strong increase in PKC-β1 immunoreactivity. The present experiments demonstrated that the increased expression of P2X7R influences PKC-β1. We predict that increased Ca(2+) concentration stimulates PKC-β1, whereas the prerequisite for activating PKC-β1 after P2X7R increase remained to be determined. Our findings suggest that PKC-β1 is important in the pathogenesis of pulmonary fibrosis. 相似文献
107.
108.
AE Clarke S Bernatsky KH Costenbader MB Urowitz DD Gladman PR Fortin M Petri S Manzi DA Isenberg A Rahman D Wallace C Gordon C Peschken MA Dooley EM Ginzler C Aranow SM Edworthy O Nived S Jacobsen G Ruiz-Irastorza E Yelin SG Barr L Criswell G Sturfelt L Dreyer I Blanco L Gottesman CH Feldman R Ramsey-Goldman 《Arthritis research & therapy》2012,14(Z3):A16
109.
Brij K. Gupta Diane M. Maher Mara C. Ebeling Vasudha Sundram Michael D. Koch Douglas W. Lynch Teresa Bohlmeyer Akira Watanabe Hiroyuki Aburatani Susan E. Puumala Meena Jaggi Subhash C. Chauhan 《The journal of histochemistry and cytochemistry》2012,60(11):822-831
MUC13 is a newly identified transmembrane mucin. Although MUC13 is known to be
overexpressed in ovarian and gastric cancers, limited information is available regarding
the expression of MUC13 in metastatic colon cancer. Herein, we investigated the expression
profile of MUC13 in colon cancer using a novel anti-MUC13 monoclonal antibody (MAb, clone
ppz0020) by immunohistochemical (IHC) analysis. A cohort of colon cancer samples and
tissue microarrays containing adjacent normal, non-metastatic colon cancer, metastatic
colon cancer, and liver metastasis tissues was used in this study to investigate the
expression pattern of MUC13. IHC analysis revealed significantly higher
(p<0.001) MUC13 expression in non-metastatic colon cancer samples
compared with faint or very low expression in adjacent normal tissues. Interestingly,
metastatic colon cancer and liver metastasis tissue samples demonstrated significantly
(p<0.05) higher cytoplasmic and nuclear MUC13 expression compared
with non-metastatic colon cancer and adjacent normal colon samples. Moreover, cytoplasmic
and nuclear MUC13 expression correlated with larger and poorly differentiated tumors. Four
of six tested colon cancer cell lines also expressed MUC13 at RNA and protein levels.
These studies demonstrate a significant increase in MUC13 expression in metastatic colon
cancer and suggest a correlation between aberrant MUC13 localization (cytoplasmic and
nuclear expression) and metastatic colon cancer. 相似文献
110.
Bonini C Grez M Traversari C Ciceri F Marktel S Ferrari G Dinauer M Sadat M Aiuti A Deola S Radrizzani M Hagenbeek A Apperley J Ebeling S Martens A Kolb HJ Weber M Lotti F Grande A Weissinger E Bueren JA Lamana M Falkenburg JH Heemskerk MH Austin T Kornblau S Marini F Benati C Magnani Z Cazzaniga S Toma S Gallo-Stampino C Introna M Slavin S Greenberg PD Bregni M Mavilio F Bordignon C 《Nature medicine》2003,9(4):367-369