Genome wide comparative analysis of the effects of PRMT5 and PRMT4/CARM1 arginine methyltransferases on the Arabidopsis thaliana transcriptome

BACKGROUND: Methylation at arginine residues (R) is an important post-translational modification that regulates a myriad of essential cellular processes in eukaryotes, such as transcriptional regulation, RNA processing, signal transduction and DNA repair. Arginine methylation is catalyzed by a family of enzymes known as protein arginine methyltransferases (PRMTs). PRMTs are classified as Type I or Type II, depending on the position of the methyl group on the guanidine of the methylated arginine. Previous reports have linked symmetric R methylation to transcriptional repression, while asymmetric R methylation is generally associated with transcriptional activation. However, global studies supporting this conclusion are not available. RESULTS: Here we compared side by side the physiological and molecular roles of the best characterized plant PRMTs, the Type II PRMT5 and the Type I PRMT4, also known as CARM1 in mammals. We found that prmt5 and prmt4a;4b mutants showed similar alterations in flowering time, photomorphogenic responses and salt stress tolerance, while only prmt5 mutants exhibited alterations in circadian rhythms. An RNA-seq analysis revealed that expression and splicing of many differentially regulated genes was similarly enhanced or repressed by PRMT5 and PRMT4s. Furthermore, PRMT5 and PRMT4s co-regulated the expression and splicing of key regulatory genes associated with transcription, RNA processing, responses to light, flowering, and abiotic stress tolerance, being candidates to mediate the physiological alterations observed in the mutants. CONCLUSIONS: Our global analysis indicates that two of the most important Type I and Type II arginine methyltransferases, PRTM4 and PRMT5, have mostly overlapping as well as specific, but not opposite, roles in the global regulation of gene expression in plants.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: Sanchez, Sabrina Elena. University of Southern California; Estados Unidos. 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: Mancini, Estefania. 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

The Eco-Physiological Role of Microcystis aeruginosa in a Changing World

Among the bloom-forming cyanobacteria, Microcystis aeruginosa is one of the mostharmful species. The prevalence of toxic species and their toxicity profiles vary each yeardepending on environmental variables, despite their dynamics being not well understood.Imbalances in nutrient concentrations, the greater frequency and intensity of higher averagetemperatures and less severe winters, and the alternation between periods of positive andnegative precipitation anomalies were identified as conditions favoring the prevalence of M.aeruginosa. Similarly, dry periods (corresponding to a prevailing La Niña condition) wereeven more conducive to the formation of harmful algal blooms of pronounced intensity.Moreover, toxin production is temperature-dependent and some strains are capable ofproducing multiple microsystins (MCs). Thus, the role of environmental variables incontrolling the genetic expression of toxin synthetase of individual toxin-producing genesis still unknown.Fil: Giannuzzi, Leda. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Hernando, Marcelo Pablo. Red de Investigación de Estresores Marinos-costeros En América Latina y El Caribe; Argentina. Comisión Nacional de Energía Atómica; Argentin

Experimental investigation of fluid flow and heat transfer in a single-phase liquid flow micro-heat exchanger

This work presents an experimental analysis of the hydrodynamic and thermal performance of micro heat exchangers. Two micro heat exchangers, characterized by microchannels of 100x100 and 200x200 µm square cross sections, were designed for that purpose. The fluid used was deionized water and there was no phase change along the fluid circuit. The fluid pressure drop along the heat exchanger and the heat transfer were measured and corrections were made to isolate the contribution of the micro channels. The results were compared with the predictions of the classical viscous flow and heat transfer theory. The main conclusions show that the experimental results fit well with these theories. No effects of heat transfer enhancement or pressure drop increase were observed as a consequence of the small scale of the microchannelsPublicad

Datos preliminares sobre los efectos crónicos de la radiación ultravioleta en la dinámica poblacional de especies fitoplanctónicas del Canal del Beagle, Argentina

Serious concerns exist that the thinning of stratospheric ozone and the resulting enhancement in the solar UVB radiation, may impair marine primary productivity. Also, UVB may alter food web dynamics and food availability for higher trophic levels in marine ecosystems inducing changes in phytoplankton species composition. The main goal of this study was to examine the responses of different species of marine phytoplankton to solar UVR. Specifically, we compared the UV sensitivity of a phytoplankton natural community isolated from the Beagle Channel (54°52´S, 68°18´W, Ushuaia, Argentina), as well as the response of two taxa which were isolated from that community (i.e., a pennate diatom, Navicula sp., and a phytoflagellate pertaining to the Class Cryptophyceae) to UV radiation. Exposure to UVB or UVA radiation treatments had no significant effects (p > 0.05) on exponential growth rate in Navicula sp. However, when the phytoflagellate [Class Cryptophyceae] was exposed to UVB, the growth rate in the exponential phase was inhibited significantly (p 0.05) en la tasa de crecimiento exponencial cuando Navicula sp. fue expuesta a UVB ó UVA (320-400 nm). Sin embargo, cuando los fitoflagelados [Clase Cryptophyceae] fueron expuestos a UVB, su tasa de crecimiento fue inhibida significativamente (p < 0.01). Al exponer a la comunidad fitoplanctónica se observaron cambios en la abundancia relativa de las especies. El porcentaje de fitoflagelados fue significativamente menor (p < 0.05) al ser expuestos a UVB comparado con PAR (400-700 nm). El porcentaje de diatomeas céntricas, en cambio, aumentó significativamente (p < 0.05). No se observaron diferencias significativas entre los diferentes días de exposición ni entre tratamientos en la respuesta de las diatomeas pennadas. El crecimiento exponencial de la comunidad fue inhibido significativamente (p < 0.01) cuando las algas fueron expuestas a UVB y UVA

The Eco-Physiological Role of Microcystis aeruginosa in a Changing World

Among the bloom-forming cyanobacteria, Microcystis aeruginosa is one of the most harmful species. The prevalence of toxic species and their toxicity profiles vary each year depending on environmental variables, despite their dynamics being not well understood. Imbalances in nutrient concentrations, the greater frequency and intensity of higher average temperatures and less severe winters, and the alternation between periods of positive and negative precipitation anomalies were identified as conditions favoring the prevalence of M. aeruginosa. Similarly, dry periods (corresponding to a prevailing La Niña condition) were even more conducive to the formation of harmful algal blooms of pronounced intensity. Moreover, toxin production is temperature-dependent and some strains are capable of producing multiple microsystins (MCs). Thus, the role of environmental variables in controlling the genetic expression of toxin synthetase of individual toxin-producing genes is still unknown.Facultad de Ciencias Exacta

Air conditioning in the region of Madrid, Spain: an approach to electricity consumption, economics and CO₂emissions

An understanding of electricity consumption due to residential air conditioning (AC) may improve production and environmental impact strategy design. This article reports on a study of peak and seasonal electricity consumption for residential air conditioning in the region of Madrid, Spain. Consumption was assessed by simulating the operation of AC units at the outdoor summer temperature characteristics of central Spain. AC unit performance when operating under part load conditions in keeping with weather conditions was also studied to find cooling demand and energy efficiency. Like wise final electricity consumption was computed and used to calculate energy costs and greenhouse gas emissions (GHGs). Cooling demand, when family holidays outside the region were factored into the calculations, came to 1.46x10⁹ kWh. Associated seasonal electricity demand was 617x10⁶ kWh and seasonal performance of AC units around 2.4. Electricity consumption in the whole region was observed to peak on 30 June 2008 at 5.44x10⁶ kW, being the load attributable to residential AC 1.79x10⁶ kW, resulting about 33% of the total peak consumption. The seasonal cost per household was about €156 and the total equivalent warming impact was 572x10³t CO₂. The method proposed can be adapted for use in other regionsThis study was funded by the Spanish Ministry of Science and Innovation under Projects INVISO, sub-project SP3 “Sustainable power generation in housing” and ENE2010-20650-C02-01. Author A. Gonzalez-Gil is grateful to the Spanish National Research Council (CSIC) for its support while he worked toward his PhD. The authors also wish to thank J. Cabetas from Iberdrola de Distribución Eléctrica S.A.U. for the information furnishedPublicad

A Role for Pre-mRNA-PROCESSING PROTEIN 40C in the Control of Growth, Development, and Stress Tolerance in Arabidopsis thaliana

Because of their sessile nature, plants have adopted varied strategies for growing and reproducing in an ever-changing environment. Control of mRNA levels and pre-mRNA alternative splicing are key regulatory layers that contribute to adjust and synchronize plant growth and development with environmental changes. Transcription and alternative splicing are thought to be tightly linked and coordinated, at least in part, through a network of transcriptional and splicing regulatory factors that interact with the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II. One of the proteins that has been shown to play such a role in yeast and mammals is pre-mRNA-PROCESSING PROTEIN 40 (PRP40, also known as CA150, or TCERG1). In plants, members of the PRP40 family have been identified and shown to interact with the CTD of RNA Pol II, but their biological functions remain unknown. Here, we studied the role of AtPRP40C, in Arabidopsis thaliana growth, development and stress tolerance, as well as its impact on the global regulation of gene expression programs. We found that the prp40c knockout mutants display a late-flowering phenotype under long day conditions, associated with minor alterations in red light signaling. An RNA-seq based transcriptome analysis revealed differentially expressed genes related to biotic stress responses and also differentially expressed as well as differentially spliced genes associated with abiotic stress responses. Indeed, the characterization of stress responses in prp40c mutants revealed an increased sensitivity to salt stress and an enhanced tolerance to Pseudomonas syringae pv. maculicola (Psm) infections. This constitutes the most thorough analysis of the transcriptome of a prp40 mutant in any organism, as well as the first characterization of the molecular and physiological roles of a member of the PRP40 protein family in plants. Our results suggest that PRP40C is an important factor linking the regulation of gene expression programs to the modulation of plant growth, development, and stress responses.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: García Hourquet, Mariano. Fundación Instituto Leloir; 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: Careno, Daniel Alejandro. 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: Iserte, Javier Alonso. 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: 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: 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

Efectos de la mezcla vertical sobre la síntesis a corto plazo de micosporinas (MAAs) en la diatomea antártica Thalasiossira sp.

One of the adaptations whereby phytoplankton can alleviate damage induced by ultraviolet radiation (280-400 nm) is the synthesis of mycosporine-like amino acids (MAAs). The synthesis of MAAs was studied after exposure of the Antarctic diatom Thalassiosira sp. isolated from Potter Cove (South Shetland Is., Antarctica) to 2 treatments with a solar simulator: surface (Sfix) and vertical mixing (Mix) irradiance conditions. Light exposure was simulated in daily cycles with maximum irradiance at noon. Only 2 MAAs, Porphyra-334 (82-85%) and Shinorine (15-18%), were identified. The concentration of the two compounds increased during experimental light exposure (50-55%) and declined in the dark (10-15%). During the light period the synthesis rate of MAAs per unit of chlorophyll a was higher in the Sfix treatment (µ=0.17 h-1) than in the Mix treatment (µ=0.05 h-1). In spite of the higher MAA levels, low cell numbers were observed in the Sfix treatment, suggesting that the algae synthesized photoprotective compounds at the expense of growth. Our results document overlapping effects of both daily light cycles and vertical mixing affecting the synthesis of MAAs. This, and the high thermal dissipation of the ultraviolet B radiation energy (280-320 nm) absorbed by these substances, suggest a rapid photoadaptive response of Thalasiossira sp. upon exposure to elevated irradiance in a stratified water column, as well as the complementary role of vertical mixing in photo-protection.La síntesis de micosporinas (MAAs) es una de las adaptaciones por las cuales el fitoplancton puede reducir los daños inducidos por la radiación ultravioleta (UVR, 280-400 nm). La síntesis de MAAs fue estudiada después de la exposición de la diatomea antártica Thalasiossira sp., aislada en Caleta Potter (Islas Shetland, Antártica), a dos tratamientos: condiciones simuladas de irradiancia en superficie (Sfix) y mezcla vertical (Mix). La luz fue simu- lada utilizando un simulador solar con ciclos diarios con irradiancia máxima al mediodía. Sólo se identificaron dos MAAs, Porphyra-334 (82-85%) y Shinorina (15-18%). La concentración de ambos compuestos aumentó durante la exposición a la luz (50-55%) y declinó en oscuridad (10-15%). Durante el período de luz, la tasa de síntesis de MAAs (calculada para cada tiempo dividiendo cada valor por el valor correspondiente de clorofila a) fue mayor en el tratamiento Sfix (µ=0.17 h-1) comparada con el tratamiento Mix (µ=0.05 h-1). A pesar de la alta concentración de MAAs, se observó un bajo número de células en el tratamiento Sfix, sugiriendo que las algas sintetizan los compuestos fotoprotectores a expensas del crecimiento. Nuestros resultados documentan una superposición de los efectos de la luz y la mezcla vertical, afectando la composición de ambas familias de MAAs. Esto, junto con la alta energía de disipación de radiación ultravioleta B (UVBR, 280-315 nm) por estas substancias, reflejan una respuesta fotoadaptativa rápida de Thalasiossira sp. en su exposición a alta irradiancia en una columna de agua estratificada, así como también el rol complementario de la mezcla vertical como factor de fotoprotección