Redox modulation of plant developmental regulators from the class I TCP transcription factor family

TEOSINTE BRANCHED1-CYCLOIDEA-PROLIFERATING CELL FACTOR1 (TCP) transcription factors participate in plant developmental processes associated with cell proliferation and growth. Most members of class I, one of the two classes that compose the family, have a conserved cysteine at position 20 (Cys-20) of the TCP DNA-binding and dimerization domain. We show that Arabidopsis (Arabidopsis thaliana) class I proteins with Cys-20 are sensitive to redox conditions, since their DNAbinding activity is inhibited after incubation with the oxidants diamide, oxidized glutathione, or hydrogen peroxide or with nitric oxide-producing agents. Inhibition can be reversed by treatment with the reductants dithiothreitol or reduced glutathione or by incubation with the thioredoxin/thioredoxin reductase system. Mutation of Cys-20 in the class I protein TCP15 abolished its redox sensitivity. Under oxidizing conditions, covalently linked dimers were formed, suggesting that inactivation is associated with the formation of intermolecular disulfide bonds. Inhibition of class I TCP protein activity was also observed in vivo, in yeast (Saccharomyces cerevisiae) cells expressing TCP proteins and in plants after treatment with redox agents. This inhibition was correlated with modifications in the expression of the downstream CUC1 gene in plants. Modeling studies indicated that Cys-20 is located at the dimer interface near the DNA-binding surface. This places this residue in the correct orientation for intermolecular disulfide bond formation and explains the sensitivity of DNA binding to the oxidation of Cys-20. The redox properties of Cys-20 and the observed effects of cellular redox agents both in vitro and in vivo suggest that class I TCP protein action is under redox control in plants.Fil: Viola, Ivana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Güttlein, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

A proof of Perko's conjectures for the Bogdanov-Takens system

The Bogdanov-Takens system has at most one limit cycle and, in the parameter space, it exists between a Hopf and a saddle-loop bifurcation curves. The aim of this paper is to prove the Perko's conjectures about some analytic properties of the saddle-loop bifurcation curve. Moreover, we provide sharp piecewise algebraic upper and lower bounds for this curve

How cultural diversity and awareness can create a more ethical AI

The European Union plans to apply specific regulations with hefty fines to enforce the ethical application of artificial intelligence. AI has inherited biases from people. However, in a global marketplace, AI should be as bias-free as possible, as it may be applied beyond the borders of the country in which it was initially developed. Hector Gonzalez-Jimenez writes that If we want to create an ethical AI it is crucial to understand the link between culture and ethics. He suggests two proactive steps to start dealing with the challenge

Single-molecule Dynamics in Protein Interactions: Characterization of RarA and RecD2 of Bacillus subtilis

Maintenance of genome integrity is one of the crucial functions in life, to preserve the appropriate genetic information, being homologous recombination a key process in the DNA repair. I have used a novel technique, using slim-field microscopy to obtain single-molecule dynamics of two poorly described proteins, RarA and RecD2, in different recombination deficient mutants and conditions to characterize them. Single-molecule microscopy has been shown as a powerful method for in vivo characterization of proteins and its interactions. Together with genetics, I have added a new level of complexity in the regulation of homologous recombination as a multiway process in which many factors are involved in different avenues with partially overlapping functions depending on the kind of DNA damage generated. I have characterized RarA and RecD2 as factors involved in recombination, but also in replication of the DNA, being part of both RecA-independent and RecA-dependent replication progression, and antagonistic regulators of RecA filamentation. RarA plays its role in replication through interactions with DnaB, and in recombination as a RecA positive regulator through its interactions with RecA, RecO, RecR, RecD2 and RecU. RarA is regulated by the RecQ-like helicases RecQ and RecS. RecD2 plays a role in chromosomal segregation that becomes essential in the absence of RecG or RuvAB, and is a negative regulator in homologous recombination that interacts with RecA, RarA, RecX, RecF and PcrA

Considerações sobre o De genesi de Nicolau de Cusa. Pensar para além da coincidentia oppositorum à luz do nome enigmático “idem”

En De docta ignorantia (1440) Nicolás de Cusa presenta la primera gran formulación de su sistema de pensamento. En De coniecturis, cuya redacción inicia en ese tiempo, no sólo completa la antropología y la teoría del conocimiento sugerida en De docta ignorantia sino también presenta la propuesta de pensar lo divino más allá de la coincidentia oppositorum. En los años siguientes, compone un conjunto de opúsculos en los que regressa sobre los temas abordados en las obras precedentes. Entre ellos ocupa un lugar notório el diálogo De genesi (1447). Allí el Cusano especula sobre uno de los temas caros a su investigación, i.e. la relación entre lo uno y lo múltiple, a través de un nuevo nombre enigmático: "idem". Nuestro trabajo busca mostrar que Nicolás de Cusa conjetura sobre aquel problema -en términos de identidad y diferencia- recogiendo su propuesta de pensar lo absoluto más allá de la coincidentia oppositorum.In De docta ignorantia (1440), Nicholas of Cusa presents the first comprehensive formulation of his system of thought. In De coniecturis, which he began writing at the time, he not only completes the anthropology and theory of knowledge, which he suggested in De docta ignorantia, but also presents the proposal of thinking the divine beyond thecoincidentia oppositorum. In the following years, he writes a group of opuscula in which he revists the topics treated in his previous works. Notorious amongst them is the dialog De genesi (1447). In it, Cusanus speculates on one of the most cherished subjects of his investigation, i.e. the relationship between the one and the multiple, by means of a new aenigmatic name: “idem”. Our work seeks to show that Nicholas of Cusa conjectures about that problem –in terms of identity and difference– in taking up his proposal of thinking the absolute beyond the coincidentia oppositorum.Fil: Gonzalez Rios, Hector Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentin

Stand structure development effects on wood quality of Melina (Gmelina arborea roxb.)

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. David LarsenVita.Ph.D. University of Missouri--Columbia 2009A stem analysis was perform to examines the effects of thinning treatments on Melina (Gmelina arborea) wood quality and tree architecture in the North Coast of Colombia. 27 plots under forest management regimes and age classes were evaluated. Split-plot experimental design, stepwise regression and ANOVA were developed to analyze the data. The results reveal that high precipitation regions have the higher values in most of the physics and mechanicals properties of the wood and dry regions have the lower values. No management regime improves wood properties rather that other regimes; but the log grade analysis was the lowest. Intermediate thinning regime was the best treatment applied to increase wood properties, wood quality and log grade in Melina trees. Estimation of log grade through the harvest cycle shows the highest increments at Cordoba region. Dendrometric variables such as heartwood, sapwood, and diameter and crown height are good estimators of tree volume, taper and branch modeling.Includes bibliographical reference

La fuerza expresiva de la metáfora "tierra de nadie": Consideraciones sobre espacios libres de dominación

Como síntomas del proceso moderno de globalización o mundialización de la cultura pueden apreciarse grandes transformaciones que han resquebrajado no sólo la certeza sino también la confianza en la existencia y posibilidad de una clara clasificación y demarcación de límites, representaciones, fronteras y órdenes. Como una de las consecuencias de estos procesos puede apuntarse el surgimiento de espacios a los que puede denominarse libres de dominación o tierras de nadie. La metáfora tierra de nadie, que bien se dibuja en el territorio que separa a dos bandos o facciones que se enfrentan en un campo de batalla. La intención de este texto breve no es denunciar irreflexivamente el carácter negativo o bien peyorativo de estos ?desórdenes? o nuevos espacios, sino más bien considerar crítica y reflexivamente la fuerza activa y creativa de tierras de nadie o espacios libres de dominación, que -por carecer de fronteras, ordenes, controles o dueños- han quedado liberados. Y esto lo mostraremos, desde una perspectiva estética, a partir de una breve memoria de la 26ª Bienal de San Pablo (2004), que tuvo por tema convocante esta metáfora.Fil: Gonzalez Rios, Hector Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentin

Technological Capabilities Asymmetries in Latin American and the Caribbean

This paper analyzes the convergence process in Latin America and the Caribbean during the 1960-2005 period. The evidence is not favorable to clear convergence or divergence trends, but to a slight process of convergence until the 1970s, and then global divergence. In turn, the results suggest the existence of transitory clubs of convergence during the 1960-1974 and 1990-1994 periods. After that, the lower income economies showed convergence to the relative richer countries, but in a context of increasing dispersion of the per capita income. The development accounting and the decomposition of the total factor productivity (TFP) indicate that those results are mainly explained by relative differences in the technological capabilities, and that the existence of structural differences is a key factor to explain the nonconvergence in technological capabilities. The efforts to integrate the economies were not enough to reduce the gap but the divergence in technological capabilities would have been worst without the integration process.Convergence; Total Factor Productivity Decomposition; Technological Capabilities; Economic Integration; Latin American and the Caribbean