10 research outputs found
An investigation into the influence of substituents and extended π-conjugation on the substitution reactions of bifunctional platinum (II) complexes.
Master of Science in Chemistry. University of KwaZulu-Natal, Pietermaritzburg 2015.Abstract available in PDF file
IDENTIFICATION OF TARGETS AND AUXILIARY PROTEINS OF PYR/PYL/RCAR ABA RECEPTORS: PROTEIN PHOSPHATASES TYPE 2C (PP2Cs) AND C2-DOMAIN ABA-RELATED PROTEINS (CARs)
[EN] ABSTRACT
Abscisic acid (ABA) signaling plays a critical role in regulating root growth and root system architecture. ABA-mediated growth promotion and root tropic response under water stress are key responses for plant survival under limiting water conditions. In this work, we have explored the role of Arabidopsis (Arabidopsis thaliana) PYR/PYL/RCAR receptors (PYRABACTIN RESISTANCE1 (PYR1)/PYR1 LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS) for root ABA signaling. As a result, we discovered that PYL8 plays a nonredundant role for the regulation of root ABA sensitivity. Unexpectedly, given the multigenic nature and partial functional redundancy observed in the PYR/PYL family, the single pyl8 mutant showed reduced sensitivity to ABA-mediated root growth inhibition. This effect was due to the lack of PYL8-mediated inhibition of several clade A phosphatases type 2C (PP2Cs), since PYL8 interacted in vivo with at least five PP2Cs, namely HYPERSENSITIVE TO ABA1 (HAB1), HAB2, ABAINSENSITIVE1 (ABI1), ABI2, and PP2CA/ABA-HYPERSENSITIVE GERMINATION3 as revealed by tandem affinity purification and mass spectrometry proteomic approaches.
Membrane-delimited abscisic acid (ABA) signal transduction plays a critical role in early ABA signaling, but the molecular mechanisms linking core signaling components to the plasma membrane are unclear. We show that transient calciumdependent interactions of PYR/PYL/RCAR ABA receptors with membranes are mediated through a 10-member family of C2-domain ABA-related (CAR) proteins in Arabidopsis thaliana. Specifically, we found that PYL4 interacted in an ABA-independent manner with CAR1 in both the plasma membrane and nucleus of plant cells. CAR1 belongs to a plant-specific gene family encoding CAR1 to CAR10 proteins, and bimolecular fluorescence complementation and coimmunoprecipitation assays showed that PYL4-CAR1 as well as other PYR/PYL-CAR pairs interacted in plant cells. The crystal structure of CAR4 was solved, which revealed that, in addition to a classical calcium-dependent lipid binding C2 domain, a specific CAR signature is likely responsible for the interaction with PYR/PYL/RCAR receptors and their recruitment to phospholipid vesicles. This interaction is relevant for PYR/PYL/RCAR function and ABA signaling, since different car triple mutants affected in CAR1, CAR4, CAR5, and CAR9 genes showed reduced sensitivity to ABA in seedling establishment and root growth assays. In summary, we identified PYR/PYL/RCAR-interacting partners that mediate a transient Ca2+-dependent interaction with phospholipid vesicles, which affects PYR/PYL/RCAR subcellular localization and positively regulates ABA signaling.[ES] RESUMEN
La señalización por la hormona vegetal ácido abscÃsico (ABA) desempeña un papel crÃtico en la regulación del crecimiento de la raÃz y en la arquitectura del sistema radical. La promoción de crecimiento de la raÃz en condiciones de estrés hÃdrico mediada por ABA es clave para la supervivencia de las plantas bajo condiciones limitantes de agua. En este trabajo, hemos explorado el papel de los receptores PYR/PYL/RCAR (PYRABACTIN RESISTANCE1 (PYR1)/PYR1 LIKE (PYL)/ REGULATORY COMPONENTS OF ABA RECEPTORS) de Arabidopsis (Arabidopsis thaliana) en la ruta de señalización de ABA en raÃz. AsÃ, hemos descubierto que el receptor de ABA PYL8 juega un papel no redundante en la regulación de la percepción de ABA en raÃz. Inesperadamente, dada la naturaleza multigénica y la redundancia funcional parcial observada en la familia PYR/PYL/RCAR, el mutante pyl8 fue el único mutante sencillo de pérdida de función de los receptores PYR/PYL/RCAR que mostraba una sensibilidad reducida a la inhibición del crecimiento mediada por ABA en raÃz. Este efecto se debe a la falta de inhibición mediada por PYL8 de varias fosfatasas del grupo A tipo 2C (PP2Cs), ya que PYL8 es capaz de interactuar in vivo con al menos cinco PP2Cs, denominadas HYPERSENSITIVE TO ABA1 (HAB1), HAB2, ABAINSENSITIVE1 (ABI1), ABI2, and PP2CA/ABA-HYPERSENSITIVE GERMINATION3 según lo han revelado la purificación por afinidad en tándem (TAP por sus siglas en inglés) y estudios proteómicos de espectrometrÃa de masas.
La transducción de la señal del ABA localizada en la membrana plasmática celular
juega un papel crucial en los pasos iniciales de la señalización de la fitohormona, pero los mecanismos moleculares que unen los componentes básicos de la señalización y la membrana plasmática no están claros. Estudiando las interacciones de los receptores del ABA PYR/PYL/RCAR con la membrana plasmática hemos encontrado que éstos pueden interaccionar transitoriamente con ella de forma dependiente de calcio gracias a una familia de proteÃnas con dominios C2 relacionadas con la ruta de señalización de ABA (denominadas C2-domain ABA-related (CAR) proteins). EspecÃficamente, se encontró que PYL4 interacciona de manera independiente de ABA con CAR1 tanto en la membrana plasmática como en el núcleo de las células vegetales. La proteÃna CAR1 pertenece a una familia multigénica constituida por 10 miembros en Arabidopsis thaliana, desde CAR1 hasta CAR10, y que solo se encuentra en plantas. Los ensayos de complementación bi-molecular de fluorescencia y de co-immunoprecipitación confirmaron la interacción en células vegetales tanto de PYL4-CAR1 como de otras parejas de PYR/PYL-CAR. La cristalización de la proteÃna CAR4 reveló que, además de un dominio C2 clásico de unión a lÃpidos dependiente de calcio, las proteÃnas de la familia CAR presentan un dominio especÃfico que probablemente es responsable de la interacción con los receptores PYR/PYL/RCAR y de su posterior reclutamiento a las vesÃculas de fosfolÃpidos. Esta interacción es relevante para la función de los receptores PYR/PYL/RCAR en la señalización del ABA, ya que diferentes mutantes triples car de pérdida de función, que tienen afectados los genes CAR1, CAR4, CAR5, y CAR9, demostraron una reducción de la sensibilidad al ABA en ensayos de establecimiento de plántula y crecimiento de la raÃz. En resumen, hemos identificado nueva familia de proteÃnas que son capaces mediar las interacciones transitorias dependientes de Ca2+ con vesÃculas de fosfolÃpidos, lo que a su vez afecta localización de PYR/PYL/RCAR y regula positivamente la señalización de ABA.[CA] RESUM
La senyalització per l'hormona vegetal à cid abcÃssic (ABA) exerceix un paper crÃtic en la regulació del creixement de l'arrel i també en l'arquitectura del sistema radical. La promoció del creixement de l'arrel en condicions d'estrés hÃdric, regulada per ABA és clau per la supervivència de les plantes sota condicions limitants d'aigua. Amb aquest treball, hem investigat el paper dels receptors PYR/PYL/RCAR (PYRABACTIN RESISTANCE1 (PYR1)/PYR1 LIKE (PYL)/ REGULATORY COMPONENTS OF ABA RECEPTORS) d'Arabidopsis (Arabidopsis thaliana) en el camà de senyalització d'ABA en arrel. AixÃ, hem descobert que el receptor d'ABA PYL8 exerceix un paper no redundant en la regulació de la percepció d'ABA en arrel. Inesperadament, donada la naturalesa multigènica i la redundà ncia funcional parcial que s'observa en la famÃlia PYR/PYL/RCAR, el mutant pyl8 va ser l'únic mutant senzill de pèrdua de funció dels receptors PYR/PYL/RCAR que mostrava una sensibilitat reduïda a la inhibició del creixement mitjançada per l'ABA en l'arrel. Doncs aquest efecte es deu a la falta d'inhibició regulada per PYL8 de diverses fosfatases del grup A tipus 2C (PP2Cs), ja que PYL8 té la capacitat d'interactuar in vivo almenys amb cinc PP2Cs, anomenades HYPERSENSITIVE TO ABA1 (HAB1), HAB2, ABAINSENSITIVE1 (ABI1), ABI2, and PP2CA/ABAHYPERSENSITIVE GERMINATION3 segons ho han revelat per una banda la purificació per afinitat en tà ndem (TAP són les seues sigles en anglés) i per altra banda, estudis proteòmics d'espectrometria de masses.
Pel que fa a la transducció del senyal del l'ABA, la qual es localitza en la membrana plasmà tica cel¿lular, juga un paper molt important en els primers instants de la senyalització de la fitohormona, no obstant això els mecanismes moleculars que uneixen els components bà sics d'aquesta senyalització amb la membrana plasmà tica, no es troben del tot clars. Per tant, s'han estudiat les interaccions que tenen els receptors del ABA PYR/PYL/RCAR amb la membrana plasmà tica, i hem trobat que aquests tenen la capacitat d'interaccionar transitòriament amb la membrana de forma dependent al calci, grà cies a una famÃlia de proteïnes amb domini C2, les quals es troben relacionades amb la ruta de senyalització d'ABA(anomenades C2domain ABArelated (CAR) proteins).EspecÃficament, es va trobar que PYL4 interacciona d'una manera independent al ABA amb CAR1, tant en la membrana plasmà tica, com en el nucli de les cèl¿lules vegetals. La proteïna CAR1 pertany a la famÃlia multigènica constituïda per 10 components en Arabidopsis thaliana, des de CAR1 fins CAR10, que tan sols es troba en plantes. Els assajos de complementació bimolecular de fluorescència i de co-immunoprecipitació, van confirmar la interacció en cèl¿lules vegetals, tant de PYL4CAR1 com d'altres parelles de PYR/PYL-CAR. La cristal¿lització de la proteïna CAR4 va revelar que, a més d'un domini C2 clà ssic de unió a lÃpids dependent del calci, les proteïnes de la famÃlia CAR presenten un domini PYR/PYL/RCAR, i del seu posterior reclutament a les vesÃcules fosfolipÃdiques. Doncs, aquesta interacció és rellevant en la funció dels receptors PYR/PYL/RCAR, ja que participa en la senyalització del l'ABA. Aquesta interacció es clau per a la funció dels receptors, ja que diferents mutants triples car de pèrdua de funció, els quals posseïxen afectats els gens CAR1, CAR4, CAR5 i CAR9, van mostrar una reducció de la sensibilitat a l'ABA en assajos d'establiment de plà ntula i creixement de l'arrel. En conclusió, hem identificat una nova famÃlia de proteïnes amb la capacitat d'organitzar les interaccions transitòries dependents del calci amb vesÃcules de fosfolÃpids, fet que al seu torn afecta la localització de PYR/PYL/RCAR i regula positivament la senyalització d'ABA.RodrÃguez Solovey, LN. (2015). IDENTIFICATION OF TARGETS AND AUXILIARY PROTEINS OF PYR/PYL/RCAR ABA RECEPTORS: PROTEIN PHOSPHATASES TYPE 2C (PP2Cs) AND C2-DOMAIN ABA-RELATED PROTEINS (CARs) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58862TESI
Advances in Remote Sensing and GIS applications in Forest Fire Management: from local to global assessments
This report contains the proceedings of the 8th International Workshop of the European Association of Remote Sensing Laboratories (EARSeL) Special Interest Group on Forest Fires, that took place in Stresa, (Italy) on 20-21 October 2011. The main subject of the workshop was the operational use of remote sensing in forest fire management and different spatial scales were addressed, from local to regional and from national to global. Topics of the workshops were also grouped according to the fire management stage considered for the application of remote sensing techniques, addressing pre fire, during fire or post fire conditions.JRC.H.7-Land management and natural hazard
ACCOUNTING DISCLOSURE, FINANCIAL TRANSPARENCY, OWNERSHIP STRUCTURE AND CORPORATE GOVERNANCE: IMPLICATIONS FOR INTERNAL AND EXTERNAL WVB JORDANIAN CREDIT RISK ASSESSMENTS
UNIVERSITY OF PLYMOUTH
UK
School of Business
Department of Accounting, Finance and Economics
ABSTRACT
Doctor of Philosophy
Accounting disclosure, financial transparency, ownership structure and corporate governance: implications for internal and external WVB Jordanian credit risk assessments
By Abdullah A.K. Al-Khawaaldah Bani Hasan (Ash-Shu’ayree As-Salafi)
Creditworthiness is a quality that is important to all stakeholders of an organisation, especially bondholders. It is posited that good corporate governance practices assist the confidence that stakeholders have in an organization’s ability to generate the strong cash flows that are needed to meet financial obligations, which in turn should enhance credit risk assessments. Much research has been conducted into rating assessments, but these have largely been directed at developed markets and they have not generally been focused on the impact of good corporate governance practices and procedures. The primary focus of this research is to address this issue through an investigation into the impact of key factors upon the credit risk assessments of listed companies on the Amman Stock Exchange (ASE) in Jordan, as assessed by World'vest Base Inc. (WVB) credit risk assessment scores for Jordanian companies between 2005 and 2007 inclusively.
Drawing upon insights from agency (including management disciplining and wealth redistribution hypotheses), stewardship, stakeholder, signalling, legitimacy and the diffusion of innovation theories, this thesis investigates the determinants of WVB credit risk assessments of Jordanian firms under five headings: accounting and financial aspects, market and regulatory perspectives, influence of ownership structure, financial transparency/disclosure and corporate governance factors. To achieve this, an array of modelling techniques is used in order to provide a more comprehensive picture. They include bivariate analysis, one-way analysis of variance, ordinary least square regressions for numerical scores, binary logistic regressions, and ordinal logistic regression.
The results demonstrate that accounting and financial factors have a significant impact on credit risk assessments but not capital intensity. Profitability is positively associated with credit risk assessments, while leverage and loss propensity have a negative association. With respect to market and regulatory factors, size and Tobin’s Q are positively associated with credit risk assessments. By contrast type of sector and audit are not related to credit risk assessments. Foreign ownership enhances ratings, whilst institutional ownership has a negative impact. Also, insider ownership and family ownership have some importance. It was surprising to find that whilst financial transparency and disclosure variables are significantly associated positively with credit risk assessments in some models, they were generally not significant across other models. Nevertheless, the study finds empirical evidence to support a degree of association between credit risk assessments and corporate governance factors. There is also a positive association between board size and credit risk assessments, but the most important aspect of corporate governance for Jordanian firms is board expertise.
The originality of this thesis also embraces the inclusion not only of externally published WVB risk assessments in the Jordanian context, but also internal numerical ratings that were made available with kind permission from the WVB agency for the purposes of this research. The question is whether there are insights that can be gained from such internal ratings that have not hitherto been made available to other researchers. The answer is in the affirmative, for role duality on the board of directors is evidently more important to WVB’s own internal numerical rating assessments than is evidenced by the WVB externally published credit risk assessments. Specifically, the significance of corporate governance (role duality) is missed by multivariate models that are based solely on externally published data. Furthermore, financial transparency and disclosure variables reveal more (albeit moderate) support for the more refined internal scores of WVB than for the external assessment ratings. Finally, family ownership is also important to WVB’s internal scores. Thus, this research has enabled deeper insights to be gained into credit risk assessment determinants within the Jordanian context.THE HASHEMIET UNIVERSITY- JORDA
Clemson Catalog, 1979-1980, Volume 54
https://tigerprints.clemson.edu/clemson_catalog/1134/thumbnail.jp
Recommended from our members
Criticism in the absence of criticism
English abstract:
Criticism is defined as the examination and judgment about someone or something. This definition includes, at first, an analytical task -with a particular methodology related to it- and, at second, a synthetic activity, translated into a value judgment on what is previously analyzed. Criticism can be done in different ways and depths: from the basic critical thinking -essentially descriptive- to the most truthful one –the poetic criticism-, that transcends pure description or analysis and refers itself to the internal coherence of the object. Any criticism that seeks to reduce the distance to the truth will address both to the intrinsic object relationships -or own laws- and to the extrinsic ones. Furthermore, an objective criticism provides a knowledge of the object regardless of the observer or frame of reference. This provides an effective method and a guaranteed way to approach to the knowledge of the object.
Does this mean that without a regular critical method no criticism is undertaken? The proposal of this paper is to
explain how a critical thought can be undertaken in the
absence of criticism, in which there is no explicit value
judgment. Taking the hypothesis that there is criticism in the absence of criticism, an architectural work –either
being a building, a writing on architecture, etc.- that implies a tacit criticism could work on two levels: as a
practical result –built, literary, etc.- and as a critical thought. The hypothesis proposes that such duality, criticism and practice, may come together in a single work. Although not in any. The existence of criticism in the absence of criticism will depend on the nature of the object and, with no doubt, on the speaker and receiver. At first glance, the guarantees provided by this criticism in the absence of criticism seem less tan through the orthodox one, in which the subject is the weakest part of the chain. However, the absence of explicit value judgment can lead to a series of stimuli –coherency, aesthetic, recreational or other- that, in certain contexts, do more viable the approach to the knowledge than through the conventional method.
Spanish abstract:
La crÃtica se define como el examen y juicio acerca de alguien o algo. Esta definición comprende, por un lado,
una tarea analÃtica -con una determinada metodologÃa
asociada- y, por otro, una actividad sintética, traducida en
un juicio de valor acerca de lo previamente analizado. La crÃtica puede hacerse de distinta forma y con distinto
grado de profundidad: desde la más básica –fundamentalmente, la crÃtica descriptiva- hasta la más veraz -la crÃtica poética-, que trasciende la descripción o el análi sis puro y se refiere a la coherencia interna del objeto de estudio. Toda crÃtica que pretenda reducir la distancia de aproximación a la verdad se ocupará tanto de las relaciones intrÃnsecas o leyes propias del objeto como de las eelaciones extrÃnsecas al mismo. Por otro lado, una crÃtica objetiva facilita el conocimiento del objeto de estudio independientemente del observador o del marco de referencia, lo que la convierte en un método eficaz y con garantÃas para la aproximación al conocimiento del objeto. Pero ¿significa esto que sin crÃtica ortodoxa no puede existir crÃtica?. La propuesta de esta comunicación es dilucidar hasta qué punto puede emprenderse una crÃtica en ausencia de crÃtica, es decir, una crÃtica en la que no sea explÃcito el juicio de valor. Tomando como hipótesis el hecho de que exista crÃtica
en ausencia de crÃtica, una obra arquitectónica –ya sea un edificio construido, un escrito sobre arquitectura, etc.- que implique una crÃtica tácita podrÃa funcionar a dos niveles: como producto práctico -edificado, literario, etc.- y como reflexión crÃtica. La hipótesis planteada propone que tal dualidad, la crÃtica y la práctica, pueda confluir en una misma obra. Aunque no en cualquiera. La existencia de crÃtica en ausencia de crÃtica dependerá de la naturaleza de la obra y, sin lugar a dudas, del emisor y el receptor del mensaje crÃtico. A primera vista, las garantÃas que ofrece la crÃtica en ausencia de crÃtica parecen menores que mediante la crÃtica ortodoxa, para la que el sujeto es la parte más débil de la cadena. Sin embargo, la ausencia de juicio de valor explÃcito puede comportar una serie de estÃmulos – de coherencia, estéticos, lúdicos, prácticos o de otra Ãndole- que, en determinados contextos, hagan más viable y clara la comprensión de la obra que a través del método convencional