1,721,023 research outputs found
Time for a change
Full text linkThe circadian clock of Arabidopsis, a popular model organism for plants, is more complex than expected, with negative feedback loops based on the repression of gene expression having a less exclusive role than previously thought.Fil: Sanchez, Sabrina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
Circadian regulation of gene expression: at the crossroads of transcriptional and post-transcriptional regulatory networks
Full text linkGene expression programs activated in response to, or in anticipation of, environmental changes involve sequential steps, from transcription and RNA processing to nuclear export and translation. Here we review recent advances in our understanding of the multiple regulatory layers that control the oscillations in gene expression associated with daily rhythms in metabolism and physiology across eukaryotic organisms. Whereas many genes show coordinated oscillations in transcription, RNA processing and translation, others show significant temporal disconnections between these processes. Thus, circadian oscillations constitute an ideal system for examining how multiple transcriptional and post-transcriptional regulatory steps are integrated to maximize organismal adjustments to environmental conditions.Fil: Beckwith, Esteban Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
Regulation of gene expression by light
Full text linkLight signals perceived mainly by phytochromes and cryptochromes regulate plant growth and development by driving dramatic shifts of the transcriptome. Early light-responsive genes include a large proportion of transcripton factors of different DNA binding motifs. Mutations at loci encoding several transcriptional regulators, including some of those showing rapid changes in transcript levels, impair responses to light in Arabidopsis thaliana. Proteasome-mediated degradation involving the E3 ligase COP1 provides an additional layer of control of the levels of transcription factors. Some transcriptional regulators are shared by light, circadian and/or hormonal signalling circuits creating complex networks that interactively integrate environmental and endogenous cues.Fil: Casal, Jorge José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
Time for circadian rhythms: plants get synchronized
Full text linkMost organisms adjust their physiology and metabolism in synchronization with the diurnal and seasonal time by using an endogenous mechanism known as circadian clock. In plants, light and temperature signals interact with the circadian system to regulate the circadian rhythmicity of physiological and developmental processes including flowering time. Recent studies in Arabidopsis thaliana now reveal that the circadian clock orchestrates not only the expression of protein coding genes but also the rhythmic oscillation of introns, intergenic regions, and noncoding RNAs. Furthermore, recent evidence showing the existence of different oscillators at separate parts of the plant has placed the spotlight on the diverse mechanisms and communicating channels that regulate circadian synchronization in plants.Fil: Más, Paloma. Consejo Superior de Investigaciones Cientificas; EspañaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin
Time to grow: circadian regulation of growth and metabolism in photosynthetic organisms
Full text linkCircadian clocks are molecular devices that help adjust organisms to periodic environmental changes. Although formally described as self-sustaining oscillators that are synchronized by external cues and produce defined outputs, it is increasingly clear that physiological processes not only are regulated by, but also regulate the function of the clock. We discuss three recent examples of the intimate relationships between the function of the clock, growth and metabolism in photosynthetic organisms: the daily tracking of sun by sunflowers, the fine computations plants and cyanobacteria perform to manage carbon reserves and prevent starvation, and the changes in clock parameters that went along with domestication of tomato.Fil: Mora Garcia, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: de Leone, María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
Transcriptional and post-transcriptional control of the plant circadian gene regulatory network
Full text linkThe circadian clock drives rhythms in multiple physiological processes allowing plants to anticipate and adjust to periodic changes in environmental conditions. These physiological rhythms are associated with robust oscillations in the expression of thousands of genes linked to the control of photosynthesis, cell elongation, biotic and abiotic stress responses, developmental processes such as flowering, and the clock itself. Given its pervasive effects on plant physiology, it is not surprising that circadian clock genes have played an important role in the domestication of crop plants and in the improvement of crop productivity. Therefore, identifying the principles governing the dynamics of the circadian gene regulatory network in plants could strongly contribute to further speed up crop improvement. Here we provide an historical as well as a current description of our knowledge of the molecular mechanisms underlying circadian rhythms in plants. This work focuses on the transcriptional and post-transcriptional regulatory layers that control the very core of the circadian clock, and some of its complex interactions with signaling pathways that help synchronize plant growth and development to daily and seasonal changes in the environment.Fil: Hernando, Carlos Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Romanowski, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
Genomic analysis reveals novel connections between alternative splicing and circadian regulatory networks
Full text linkCircadian clocks, the molecular devices present in almost all eukaryotic and some prokaryotic organisms, phase biological activities to the most appropriate time of day. These devices are synchronized by the daily cycles of light and temperature, and control hundreds of processes, ranging from gene expression to behavior as well as reproductive development. For a long time, these clocks were considered to operate primarily through regulatory feedback loops that act at the transcriptional level. Recent studies, however, conclusively show that circadian rhythms can persist in the absence of transcription, and it is evident that robust and precise circadian oscillations require multiple regulatory mechanisms operating at the co-/post-transcriptional, translational, post-translational and metabolic levels. Furthermore, these different regulatory loops exhibit strong interactions, which contribute to the synchronization of biological rhythms with environmental changes throughout the day and year. Here, we describe recent advances that highlight the role of alternative splicing (AS) in the operation of circadian networks, focusing on molecular and genomic studies conducted in Arabidopsis thaliana. These studies have also enhanced our understanding of the mechanisms that control AS and of the physiological impact of AS.Fil: Perez Santangelo, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires; ArgentinaFil: Schlaen, Rubén Gustavo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Agronomia; Argentin
Conserved and divergent signals in 5’ splice site sequences across fungi, metazoa and plants
Full text linkIn eukaryotic organisms the ensemble of 5’ splice site sequences reflects the balance between natural nucleotide variability and minimal molecular constraints necessary to ensure splicing fidelity. This compromise shapes the underlying statistical patterns in the composition of donor splice site sequences. The scope of this study was to mine conserved and divergent signals in the composition of 5’ splice site sequences. Because 5´ donor sequences are a major cue for proper recognition of splice sites, we reasoned that statistical regularities in their composition could reflect the biological functionality and evolutionary history associated with splicing mechanisms. Results: We considered a regularized maximum entropy modeling framework to mine for non-trivial two-site correlations in donor sequence datasets corresponding to 30 different eukaryotes. For each analyzed species, we identified minimal sets of two-site coupling patterns that were able to replicate, at a given regularization level, the observed one-site and two-site frequencies in donor sequences. By performing a systematic and comparative analysis of 5’splice sites we showed that lineage information could be traced from joint di-nucleotide probabilities. We were able to identify characteristic two-site coupling patterns for plants and animals, and propose that they may echo differences in splicing regulation previously reported between these groups.Fil: Beckel, Maximiliano Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Kaufman, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Chernomoretz, Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin
Molecular and genetic bases underlying the cross-talk between photomorfogenic and pathogen response pathways
Full text linkLa luz es uno de los principales factores ambientales que regulan el crecimiento y desarrollo de las plantas. A lo largo de su ciclo de vida, desde la germinación hasta la floración, las plantas monitorean la intensidad, la longitud de onda, la dirección y la duración de la luz y utilizan la información del ambiente lumínico para optimizar su desarrollo. La percepción de las señales lumínicas está mediada por fotorreceptores específicos como los fitocromos, del rojo al rojo lejano. En Arabidopsis thaliana, existen 5 fitocromos diferentes (PHYA, PHYB, PHYC, PHYD y PHYE). La percepción de los cambios en el ambiente lumínicos asociados a la presencia de plantas vecinas acelera el crecimiento de los tallos, la floración e induce la hiponastia. Conjuntamente estos cambios en el desarrollo se denominan síndrome de escape al sombreado y están mediados principalmente por el PHYB. Este trabajo aporta nuevos elementos para comprender los mecanismos implicados en la transducción de las señales lumínicas en plantas a través de la identificación de nuevos componentes involucrados en la vía de señalización del fitocromo B. En esta tesis se aisló y caracterizó al mutante csa1 (del inglés constitutive shade avoidance) por presentar el síndrome de escape al sombreado aún creciendo en condiciones no inductivas. csa1 posee una inserción de T-DNA en el segundo exón de un gen TIR-NBS-LRR (del inglés Toll/Interleukin1 receptor-nucleotide binding site-leucinerich repeat), generando así una proteína truncada que interfiere en la señalización de otras proteínas con dominios TIR. Hasta el momento las proteínas TIR-NBS-LRR habían sido implicadas únicamente en las respuestas de defensa en plantas; nuestros resultados indican que además estarían involucradas en la modulación de la vía de señalización del fitocromo B a través de la regulación de la expresión de PIF3. Además, detectamos que los niveles de expresión de los genes PIF3 y PIF4 (dos genes involucrados en las respuestas ftomorfogénicas) varían luego de la infección con Pseudomonas syringae. Finalmente, los resultados de estas tesis muestran que el mutante eds4 aislado originalmente por ser hipersensible a la infección con bacterias, está afectado en las vías de transducción de las señales lumínicas. En conjunto, los resultados de este trabajo constituyen el primer paso para comprender los mecanismos moleculares implicados en la interacción o cross-talk entre las vías de señalización que conducen a las respuestas foromorfogénicas y las que regulan las respuestas de resistencia frente al ataque de los patógenos.Light is a critical factor for plant development. Plants monitor the intensity, quality, direction and duration of light and use the information to adapt and optimize their growth and development. Perception of light signal is mediated by specific photoreceptors such as phytochromes. Phytochromes are encoded by a family of five genes in Arabidopsis thaliana (PHYA, PHYB, PHYC, PHYD y PHYE). In plants, light signals generated by the presence of neighbors accelerate stem growth, flowering, and induce a more erect position of the leaves, a developmental strategy known as shade-avoidance syndrome. PHYB is the major contributor to shade avoidance responses. In this work we shed light on the mechanisms of light transduction, identifying new PHYB signaling components. We describe the constitutive shade-avoidance 1 mutant (csa1), which shows a shade- avoidance phenotype in the absence of shade. This mutant has a T-DNA inserted within the second exon of a Toll/Interleukin1 receptornucleotide binding site-leucine-rich repeat (TIR-NBS-LRR) gene, which leads to the production of a truncated protein that, in turn, interferes with TIR-proteins signaling. So far, TIR-NBS-LRR proteins had been only implicated in pathogen defense responses in plants. Our results show that they are also involved in PHYB signaling modulation, regulating PIF3 gene expression. In addition, we detected that PIF3 and PIF4 (two genes implicated in photomorphogenic responses) mRNA level changes after Pseudomonas syringae infection. Finally, we show that the eds4 mutant, which was originally isolated for displaying enhanced disease susceptibility to P. syringae, it is also defective in light signaling. Taken together, our findings constitutes a first step towards understanding the molecular mechanisms underlying the cross talk observed between photomorphogenic and defense responses.Fil:Faigón Soverna, Ana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Time-dependent sequestration of RVE8 by LNK proteins shapes the diurnal oscillation of anthocyanin biosynthesis
Full text linkCircadian clocks sustain 24-h rhythms in physiology and metabolism that are synchronized with the day/night cycle. In plants, the regulatory network responsible for the generation of rhythms has been broadly investigated over the past years. However, little is known about the intersecting pathways that link the environmental signals with rhythms in cellular metabolism. Here, we examine the role of the circadian components REVEILLE8/LHY-CCA1-LIKE5 (RVE8/LCL5) and NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED genes (LNK) shaping the diurnal oscillation of the anthocyanin metabolic pathway. Around dawn, RVE8 up-regulates anthocyanin gene expression by directly associating to the promoters of a subset of anthocyanin biosynthetic genes. The up-regulation is overcome at midday by the repressing activity of LNK proteins, as inferred by the increased anthocyanin gene expression in lnk1/lnk2 double mutant plants. Chromatin immunoprecipitation assays using LNK and RVE8 misexpressing plants show that RVE8 binding to target promoters is precluded in LNK overexpressing plants and conversely, binding is enhanced in the absence of functional LNKs, which provides a mechanism by which LNKs antagonize RVE8 function in the regulation of anthocyanin accumulation. Based on their previously described transcriptional coactivating function, our study defines a switch in the regulatory activity of RVE8-LNK interaction, from a synergic coactivating role of evening-expressed clock genes to a repressive antagonistic function modulating anthocyanin biosynthesis around midday.Fil: Pérez García, Pablo. Consejo Superior de Investigaciones Cientificas; EspañaFil: Ma, Yuan. Consejo Superior de Investigaciones Cientificas; EspañaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Mas, Paloma. Consejo Superior de Investigaciones Cientificas; Españ
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