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

Do Physical Activity, Diet and Sex Modify the Association Between Neurotrophin Single Nucleotide Polymorphisms and Insomnia?

Sleep disturbance is common in older adults at prevalence rates ranging between 30 - 50% in the United States. Neurotrophins such as brain-derived neurotrophic factor (BDNF), play a role in sleep (Bachmann et al., 2012) as do lifestyle factors such as physical activity (Dolezal et al., 2017) and diet. This study examined the associations of selected single nucleotide polymorphisms or SNPs related to BDNF or its receptors and lifestyle factors of physical activity and diet, as well as their interactions on the risk for sleep disturbance in older adult males and females. This thesis examined existing data from the Cache County Study on Memory and Aging (CCSMA), a longitudinal, population study of 5,092 individuals aged 65 years and older residing in Cache County, Utah. The results suggest that SNPs related to BDNF or its receptors were not related to sleep problems in either males or females. In males, increased physical activity reduced the likelihood of experiencing sleep disturbances, while unexpectedly, greater adherence to the Mediterranean diet slightly increased the likelihood of reporting sleep problems. In females, the SNPs and lifestyle choices did not appear to have any relationship with sleep disturbance. However, an interaction between the BDNF gene Val66Met and physical activity showed a trend. Specifically, females with the minor and less common allele who reported sedentary-to-light physical activity exhibited a 45% increase in risk of sleep disturbance compared to those who reported moderate-to-vigorous physical activity. Overall, this study suggests that SNPs related to BDNF or its receptors had no significant association with sleep disturbance, but that some effects may be specific to males or females. Increasing physical activity may be beneficial for males with sleep disturbance as well as for females, but for the latter, only for a certain BDNF genetic profile. Future studies may wish to further explore sex-dependent associations between genes and lifestyle factors in improving sleep disturbance in older adults

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