1,721,054 research outputs found
Dynamic GOLVEN-ROOT GROWTH FACTOR 1 INSENSITIVE signaling in the root cap mediates root gravitropism
No full textThroughout exploration of the soil, roots interact with their environment and adapt to different conditions. Directional root growth is guided by asymmetric molecular patterns but how these become established or are dynamically regulated is poorly understood. Asymmetric gradients of the phytohormone auxin are established during root gravitropism, mainly through directional transport mediated by polarized auxin transporters. Upon gravistimulation, PIN-FORMED2 (PIN2) is differentially distributed and accumulates at the lower root side to facilitate asymmetric auxin transport up to the elongation zone where it inhibits cell elongation. GOLVEN (GLV) peptides function in gravitropism by affecting PIN2 abundance in epidermal cells. In addition, GLV signaling through ROOT GROWTH FACTOR 1 INSENSITIVE (RGI) receptors regulates root apical meristem maintenance. Here, we show that GLV-RGI signaling in these two processes in Arabidopsis (Arabidopsis thaliana) can be mapped to different cells in the root tip and that, in the case of gravitropism, it operates mainly in the lateral root cap (LRC) to maintain PIN2 levels at the plasma membrane. Furthermore, we found that GLV signaling upregulates the phosphorylation level of PIN2 in an RGI-dependent manner. In addition, we demonstrated that the RGI5 receptor is asymmetrically distributed in the LRC and accumulates in the lower side of the LRC after gravistimulation. Asymmetric GLV-RGI signaling in the root cap likely accounts for differential PIN2 abundance at the plasma membrane to temporarily support auxin transport up to the elongation zone thereby representing an additional level of control on the asymmetrical auxin flux to mediate differential growth of the root
Phosphatidylinositol 4-phosphate accumulates extracellularly upon xylanase treatment in tomato cell suspensions
Full text linkVarious phosphoinositides have been implicated in plant defence signalling. Until now, such molecules have been exclusively related to intracellular signalling. Here, evidence is provided for the detection of extracellular phosphatidylinositol 4-phosphate (PI4P) in tomato cell suspensions. We have analysed and compared the intracellular and extracellular phospholipid profiles of [(32)P(i)]-prelabelled tomato cells, challenged with the fungal elicitor xylanase. These phospholipid patterns were found to be different, being phosphatidylinositol phosphate (PIP) the most abundant phospholipid in the extracellular medium. Moreover, while cells responded with a typical increase in phosphatidic acid and a decrease in intracellular PIP upon xylanase treatment, extracellular PIP level increased in a time- and dose-dependent manner. Using two experimental approaches, the extracellular PIP isoform was identified as PI4P. Addition of PI4P to tomato cell suspensions triggered the same defence responses as those induced by xylanase treatment. These include production of reactive oxygen species, accumulation of defence-related gene transcripts and induction of cell death. We demonstrate that extracellular PI4P is accumulated in xylanase-elicited cells and that exogenous application of PI4P mimics xylanase effects, suggesting its putative role as an intercellular signalling molecule.Fil: Gonorazky, Ana Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Laxalt, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Testerink, Christa. University of Amsterdam; Países BajosFil: Munnik, Teun. University of Amsterdam; Países BajosFil: de la Canal, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin
The role of signaling phospholipids in the regulation of plant polar growth
No full textPolar cell growth is one of the most fundamental processes in plant development. Pollen tubes represent excellent experimental system to study basic rules of this phenomenon. Polar growth is governed by a precise spatiotemporal coordination of various molecules, such as small GTPases, actin cytoskeleton, protein kinases and reactive oxygen species, to achieve its establishment and maintenance. In this study, we utilized a combination of diverse experimental approaches together with advanced computational methods to investigate the role of two signaling phospholipids, phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphophate (PIP2) in the polar growth. We described the involvement of PA in the regulation of actin cytoskeleton, which dynamics is essential for the proper pollen tube growth. We found direct interaction of actin with the PA-producing enzyme, phospholipase D (PLDβ)1 and we showed that actin affects the activity of PLDβ. We further described structural details of the PA inhibition of actin-capping protein and we proposed the model of positive- feedback loop of the actin dynamics regulation by PA and PLDβ1. To get insight into the PA localization in pollen tubes, we prepared PA-binding domain of Spo20p as YFP-fusion protein and we used it as PA-biosensor. We found that PA is enriched..
The role of signaling phospholipids in the regulation of plant polar growth
No full textPolar cell growth is one of the most fundamental processes in plant development. Pollen tubes represent excellent experimental system to study basic rules of this phenomenon. Polar growth is governed by a precise spatiotemporal coordination of various molecules, such as small GTPases, actin cytoskeleton, protein kinases and reactive oxygen species, to achieve its establishment and maintenance. In this study, we utilized a combination of diverse experimental approaches together with advanced computational methods to investigate the role of two signaling phospholipids, phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphophate (PIP2) in the polar growth. We described the involvement of PA in the regulation of actin cytoskeleton, which dynamics is essential for the proper pollen tube growth. We found direct interaction of actin with the PA-producing enzyme, phospholipase D (PLDβ)1 and we showed that actin affects the activity of PLDβ. We further described structural details of the PA inhibition of actin-capping protein and we proposed the model of positive- feedback loop of the actin dynamics regulation by PA and PLDβ1. To get insight into the PA localization in pollen tubes, we prepared PA-binding domain of Spo20p as YFP-fusion protein and we used it as PA-biosensor. We found that PA is enriched..
Úloha signálních fosfolipidů v regulaci polárního růstu rostlin
No full textPolární růst patří mezi jeden z nejdůležitějších procesů ve vývoji rostlin. Pylové láčky představují vynikající experimentální systém pro studium mechanismů polárního růstu. Tento typ růstu je kontrolován přesnou časo-prostorovou koordinací molekul jako jsou např. malé GTPasy, aktinový cytoskelet, protein kinasy nebo reaktivní formy kyslíku. V této práci jsme se zaměřili na studium role dvou signálních fosfolipidů, kyseliny fosfatidové (PA) a fosfatidylinositol 4,5-bisfosfátu (PIP2), v regulaci polárního růstu rostlin. Kombinací biochemických a molekulárně- biologických metod jsme popsali zapojení PA v regulaci aktinového cytoskeletu, jehož dynamika je nezbytná pro správný růst pylových láček. Nalezli jsme přímou interakci enzymu, který produkuje PA, fosfolipasy D (PLD)β1 s aktinem a ukázali jsme, že aktin ovlivňuje aktivitu tohoto enzymu. Pomocí molekulárně-dynamických simulací jsme popsali strukturní detaily inhibice aktin-čepičku-jícího proteinu PA a navrhli jsme model pozitivní zpětné vazby v regulaci aktinové dynamiky zprostředkované PA a PLDβ1. Abychom získali informace o lokalizaci PA, připravili jsme PA-vazebnou doménu proteinu Spo20p ve fúzi s YFP a tuto doménu jsme použili jako PA-biosensor. V pylových láčkách se PA lokalizuje do subapikální oblasti a částečně se překrývá se signálem pro...Polar cell growth is one of the most fundamental processes in plant development. Pollen tubes represent excellent experimental system to study basic rules of this phenomenon. Polar growth is governed by a precise spatiotemporal coordination of various molecules, such as small GTPases, actin cytoskeleton, protein kinases and reactive oxygen species, to achieve its establishment and maintenance. In this study, we utilized a combination of diverse experimental approaches together with advanced computational methods to investigate the role of two signaling phospholipids, phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphophate (PIP2) in the polar growth. We described the involvement of PA in the regulation of actin cytoskeleton, which dynamics is essential for the proper pollen tube growth. We found direct interaction of actin with the PA-producing enzyme, phospholipase D (PLDβ)1 and we showed that actin affects the activity of PLDβ. We further described structural details of the PA inhibition of actin-capping protein and we proposed the model of positive- feedback loop of the actin dynamics regulation by PA and PLDβ1. To get insight into the PA localization in pollen tubes, we prepared PA-binding domain of Spo20p as YFP-fusion protein and we used it as PA-biosensor. We found that PA is enriched...Department of Experimental Plant BiologyKatedra experimentální biologie rostlinFaculty of SciencePřírodovědecká fakult
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Shape up your root: Novel cellular pathways mediating root responses to salt stress and phosphate starvation
Full text linkDuring their entire life cycle, plants have to cope with changing environmental conditions. Water scarcity, nutrient deprivation and soil salinization are some of the biggest constrains wild plants and crops are facing, and the scale of these problems is predicted to rise in the years to come. Despite the fact that plants are rooted in one place, their roots do not have an entirely sessile character. The root is the first organ that perceives the changes in soil conditions. Plants are able to allocate root biomass towards more favorable regions, for example richer in nutrients or water, or develop root system optimal for coping with abiotic stresses, like salinity. In field conditions, plants are often subjected to combinations of abiotic stresses, which urge the study of effects of multiple concurrent stresses. Modulation of Root System Architecture (RSA) traits is a pivotal component describing responses to environmental factors and root growth and development were suggested as a focus area for breeding strategies towards high-yield crops grown in harsh conditions. This thesis focuses on the modulation of Root System Architecture by two environmental stresses, salinity and phosphate deprivation, and dissecting the molecular base of these responses, including the integration of these two stresses
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