175 research outputs found

    Evoluci贸n de la v铆a fotoperi贸dica en algas y plantas

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    Las plantas han desarrollado mecanismos muy efectivos para detectar cambios en el medio y modificar su crecimiento de manera acorde. Esta plasticidad en su desarrollo les confiere una 贸ptima adaptaci贸n al medio y un enorme 茅xito reproductivo. Una de las se帽ales que m谩s influencia tiene sobre el desarrollo vegetal es la longitud del d铆a o fotoperiodo. La capacidad para detectar la longitud del d铆a depende de se帽ales procedentes del reloj, de los fotorreceptores y de v铆as de se帽alizaci贸n complejas que afectan procesos cruciales del desarrollo como la floraci贸n, la dormici贸n de las yemas, la germinaci贸n o la senescencia. Nuestro trabajo se centra en entender c贸mo se regula este proceso a nivel molecular y para ello empleamos t茅cnicas de 煤ltima generaci贸n como prote贸mica de complejos proteicos o la construcci贸n de redes de co-expresi贸n g茅nica. Para entender estos procesos complejos en plantas empleamos como modelo Arabidopsis thaliana y el alga unicelular Chlamydomonas reinhardtii donde describimos por primera vez la existencia de esta ruta fotoperi贸dica y caracterizamos algunos de sus componentes principales. Conocer los mecanismos moleculares sencillos que rigen la respuesta fotoperi贸dica en algas nos ayuda a entender procesos complejos en plantas superiores. Adem谩s, como valor a帽adido, empleamos herramientas derivadas del conocimiento sobre la ruta fotoperi贸dica en algas y plantas para modificar la variaci贸n del tiempo de reproducci贸n de especies con inter茅s agrario y el rendimiento de cosechas, lo que tiene importantes implicaciones biotecnol贸gicas.Universidad de M谩laga. Campus de excelencia Internacional Andalucia Tec

    CONSTANS and the evolutionary origin of photoperiodic timing of flowering

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    A network of promoting and inhibiting pathways that respond to environmental and internal signals controls the flowering transition. The outcome of this regulatory network establishes, for any particular plant, the correct time of the year to flower. The photoperiod pathway channels inputs from light, day length, and the circadian clock to promote the floral transition. CONSTANS (CO) is a central regulator of this pathway, triggering the production of the mobile florigen hormone FT (FLOWERING LOCUS T) that induces flower differentiation. Because plant reproductive fitness is directly related to its capacity to flower at a precise time, the photoperiod pathway is present in all known plant species. Recent findings have stretched the evolutionary span of this photophase signal to unicellular algae, which show unexpected conserved characteristics with modern plant photoperiodic responses. In this review, a comparative description of the photoperiodic systems in algae and plants will be presented and a general role for the CO family of transcriptional activators proposed.Gobierno de Andaluc铆a P08鈥怉GR鈥03582Ministerio de Ciencia e Innovaci贸n CSIC鈥200920I181, BIO2007鈥6183

    Field evaluation of winterkill in annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis stolonifera L.)

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    Winterkill, in putting greens and fairways of annual bluegrass ( Poa annua L.) and creeping bentgrass (Agrostis stolonifera L.), is a common phenomenon in North-Central Region of United States and in other temperate areas. Extensive research in controlled environments has evaluated injury mechanisms in creeping bentgrass and annual bluegrass. A large number of studies have evaluated winter injury in other turfgrass species and in cereal grasses. Most agree that damages can be explained by factors such as intracellular and extracellular ice formation, cellular dehydration and hydration, plant desiccation, macro scale tissue and organ rupture, diseases, anoxia, cellular acidosis, oxidative stress and retarded growth. Despite the vast amount of information generated during several decades of research, winterkill in creeping bentgrass and annual bluegrass is a problem that still leaves golf course superintendent with many unanswered questions.;It is proposed that, to minimize winterkill, it is necessary to understand the high complexity of the system at field level and not only in controlled environments.;The purpose of this research was to quantify the relative injury on putting greens as it relates to snow cover, ice formation, desiccation, crown hydration, and freeze/thaw cycles. Our approach was to evaluate the relative amount of injury that is associated with various scenarios of winter, instead of focusing solely on the mechanisms that cause the injury. Also, it is of interest to determine not only what condition causes the most winter injury, but when during the season does damage occur and if it is worth the expense or effort to try and minimize the injury by taking action.;This study was conducted at the Iowa State University (ISU) Horticulture Research Center and at ISU Veenker Memorial golf course, both in Ames Iowa. The species evaluated were creeping bentgrass (Agrostis stolonifera L) and annual bluegrass (Poa annua L). Ten possible winter scenarios; dry/open, wet, ice continuous, snow continuous, impermeable artificial cover and ice continuous, ice removal, ice/melt freeze, snow removal/melt freeze, an artificial permeable turf cover, and artificial permeable turf cover with snow, were created on two Iowa putting greens in January, February and March of 2003, 2004, and 2005. Dry weight yield produced by samples collected in the field and grown on controlled chambers was used to indicate the amount of winter injury. Hourly temperatures were registered through the length of the study. Growing degree days (GDD) and stress degree days (SDD) were calculated with temperature data.;Creeping bentgrass was not killed under any treatment. Continuous ice cover of 66 days caused creeping bentgrass bleaching but never resulted in any turf kill or decline in creeping bentgrass cover. Annual bluegrass was susceptible to winter injury when exposed to ice encasement. Damages by ice formation occurred during the first 15 days after encasement. The formation and type of ice is more important than the duration of ice cover in predicting annual bluegrass winter injury when ice is present. In both species, the treatments that offered a better visual quality at the end of the winter period were those that had a better protection such as impermeable-ice, permeable-snow, and snow treatments. However, the visual results did not necessarily mirror on those results of biomass production.;In regard to temperatures and insulation characteristics of winter practices, greens without any protective layer suffer almost twice the amount of stress degrees that snow covered plots. As accumulative units, SDD 0掳C had larger mean separation than any of the temperature variables; as such it was a better descriptor of intensity or risk of damage than temperatures alone. In the north central region of the United States, the use of artificial covers combined with snow blankets provided the best insulation and therefore the best condition for turf survival and early spring turf quality.;Keywords. winterkill, annual bluegrass, creeping bentgrass, ice, temperature, stress degree day

    Determination of Soluble Sugars in Arabidopsis thaliana Leaves by Anion Exchange Chromatography

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    Determination of soluble sugars is basic for the study of carbon metabolism in plants. Soluble sugar quantitation can be achieved by enzymatic methods implying different coupled reactions. Here we describe a simple method that allows rapid determination of the most abundant soluble sugars (glucose, fructose and sucrose) in Arabidopsis leaves by anion exchange chromatography. We have applied this method to study the levels of soluble sugars during the photoperiodic transition to flowering (Ortiz-Marchena et al., 2014).Espa帽a, MINECO projects CSD2007-00057, BIO2008-02292, and BIO2011-28847-C02-00Espa帽a, Junta de Andaluc铆a P06-CVI-01450 and P08-AGR-0358

    Architectural design and construction costs, tools towards territorial sustainability

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    This paper is presented in CIB: Management and Innovation Sustainable Built Environment 2011, as the study and analysis of the residential model of a rural area from the Iberian Peninsula, specifically applied to the case of the province of C谩ceres, in the autonomous region of Extremadura, in Spain. To this end, from a database made up of building projects whose real costs are known, it is intended to establish the links of the different parameters studied through the corresponding functions of statistical analysis. One of the main objectives of this process is constituted by the possibility of establishing those design variables of higher economic importance, so as to keep an economic control of these parameters, generally geometrical and typological, from the very start of the project. And, in general, a higher optimization of resources in the construction of dwellings in the rural environment from their design is intended

    Purification of Starch Granules from Arabidopsis Leaves and Determination of Granule-Bound Starch Synthase Activity

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    Starch constitutes the most important carbon reserve in plants and is composed of branched amylopectin and linear amylose. The latter is synthesized exclusively by the Granule-Bound Starch Synthase (GBSS, EC 2.4.1.21). Here we report a readily reproducible, specific and highly sensitive protocol, which includes the isolation of intact starch granules from Arabidopsis thaliana leaves and the subsequent determination of GBSS activity. We have applied this method to study GBSS activity in diurnal cycles in vegetative growth and during the photoperiodic transition to flowering in Arabidopsis (Tenorio et al., 2003; Ortiz-Marchena et al., 2014).Espa帽a,MINECO CSD2007-00057, BIO2008-02292, and BIO2011-28847-C02-00Espa帽a, Junta de Andaluc铆a P06-CVI-01450 and P08-AGR-0358

    Ubiquitin carboxyl-terminal hydrolases are required for period maintenance of the circadian clock at high temperature in Arabidopsis

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    Protein ubiquitylation participates in a number of essential cellular processes including signal transduction and transcription, often by initiating the degradation of specific substrates through the 26S proteasome. Within the ubiquitin-proteasome system, deubiquitylating enzymes (DUBs) not only help generate and maintain the supply of free ubiquitin monomers, they also directly control functions and activities of specific target proteins by modulating the pool of ubiquitylated species. Ubiquitin carboxyl-terminal hydrolases (UCHs) belong to an enzymatic subclass of DUBs, and are represented by three members in Arabidopsis, UCH1, UCH2 and UCH3. UCH1 and UCH2 influence auxin-dependent developmental pathways in Arabidopsis through their deubiquitylation activities, whereas biological and enzymatic functions of UCH3 remain unclear. Here, we demonstrate that Arabidopsis UCH3 acts to maintain the period of the circadian clock at high temperatures redundantly with UCH1 and UCH2. Whereas single uch1, uch2 and uch3 mutants have weak circadian phenotypes, the triple uch mutant displays a drastic lengthening of period at high temperatures that is more extreme than the uch1 uch2 double mutant. UCH3 also possesses a broad deubiquitylation activity against a range of substrates that link ubiquitin via peptide and isopeptide linkages. While the protein target(s) of UCH1-3 are not yet known, we propose that these DUBs act on one or more factors that control period length of the circadian clock through removal of their bound ubiquitin moieties, thus ensuring that the clock oscillates with a proper period even at elevated temperature

    Seeding Rates versus Various Levels of Simulated Football Traffic

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    The purpose of this study was to determine the optimal seeding rates for turfgrass species under various simulated traffic levels

    Widespread occurrence of non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase among gram-positive bacteria

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    The non-phosphorylating glyceraldehyde 3-phosphate dehydrogenase (GAPDHN, NADP+-specific, EC 1.2.1.9) is present in green eukaryotes and some Streptococcus strains. The present report describes the results of activity and immunoblot analyses, which were used to generate the first survey of bacterial GAPDHN distribution in a number of Bacillus, Streptococcus and Clostridium strains. Putative gapN genes were identified after PCR amplification of partial 700-bp sequences using degenerate primers constructed from highly conserved protein regions. Alignment of the amino acid sequences of these fragments with those of known sequences from other eukaryotic and prokaryotic GAPDHNs, demonstrated the presence of conserved residues involved in catalytic activity that are not conserved in aldehyde dehydrogenases, a protein family closely linked to GAPDHNs. The results confirm that the basic structural features of the members of the GAPDHN family have been conserved throughout evolution and that no identity exists with phosphorylating GAPDHs. Furthermore, phylogenetic trees generated from multiple sequence alignments suggested a close relationship between plant and bacterial GAPDHN families. [Int Microbiol 2005; 8(4):251-258
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