Signal integration on plant promoters A case study in maize

Gene promoters perceive numerous signals and integrate this information into a single response, the transcriptional activity of a gene. It was speculated that covalent modification of histones on the promoters might have an important function in storage and integration of signals. Using the genes for the core proteins of C4 metabolism in maize as a model, we associated the perception of specific signals with the establishment of individual histone modifications. Core elements of the histone code defined in these studies are conserved on all C4 genes and on other maize genes that respond to similar stimuli. Moreover, the code is used in independent C4 lineages. However, our data also advise caution because interpretation of histone modifications might differ dependent on the promoter position of the modification. The model provided here constitutes a starting point for genome-wide decoding of stimulus-modification pairs in epigenetic gene regulation.DFG/PE819/1-

Core promoter acetylation is not required for high transcription from the phosphoenolpyruvate carboxylase promoter in maize

<p>Abstract</p> <p>Background</p> <p>Acetylation of promoter nucleosomes is tightly correlated and mechanistically linked to gene activity. However, transcription is not necessary for promoter acetylation. It seems, therefore, that external and endogenous stimuli control histone acetylation and by this contribute to gene regulation. Photosynthetic genes in plants are excellent models with which to study the connection between stimuli and chromatin modifications because these genes are strongly expressed and regulated by multiple stimuli that are easily manipulated. We have previously shown that acetylation of specific histone lysine residues on the photosynthetic phosphoenolpyruvate carboxylase (<it>Pepc</it>) promoter in maize is controlled by light and is independent of other stimuli or gene activity. Acetylation of upstream promoter regions responds to a set of other stimuli which include the nutrient availability of the plant. Here, we have extended these studies by analysing histone acetylation during the diurnal and circadian rhythm of the plant.</p> <p>Results</p> <p>We show that histone acetylation of individual lysine residues is removed from the core promoter before the end of the illumination period which is an indication that light is not the only factor influencing core promoter acetylation. Deacetylation is accompanied by a decrease in gene activity. Pharmacological inhibition of histone deacetylation is not sufficient to prevent transcriptional repression, indicating that deacetylation is not controlling diurnal gene regulation. Variation of the <it>Pepc </it>promoter activity during the day is controlled by the circadian oscillator as it is maintained under constant illumination for at least 3 days. During this period, light-induced changes in histone acetylation are completely removed from the core promoter, although the light stimulus is continuously applied. However, acetylation of most sites on upstream promoter elements follows the circadian rhythm.</p> <p>Conclusion</p> <p>Our results suggest a central role of upstream promoter acetylation in the quantitative regulation of gene expression in this model gene. Induced core promoter acetylation is dispensable for the highest gene expression in the diurnal and circadian rhythm.</p

A further step toward a thermochronological 3-D model of the SE Black Forest

Fission-track (FT) data always depend on the thermal history of a 3-D geological complex. Therefore it is expedient to display FT data sets in 3-D models. Such a model in which tectonic, sedimentological and hydrological features are combined can greatly improve the interpretation of the palaeo-thermal pattern derived from FT analyses. Since 1988 several FT studies have been conducted in the Black Forest (BF) (Michalski 1988, Wyss 2000, Timar- Geng et al. 2004, 2005). Timar-Geng et al. (2006) analyse the crystalline basement and the Permian Rotliegend beneath the Mesozoic units in the Tabular Jura (TJ) east of Basel, Switzerland, using samples taken from the three Nagra boreholes at Kaisten, Riniken and Leuggern. In particular Timar-Geng et al. (2005, 2006) characterise the thermal history of this pre-Mesozoic basement. For the BF they estimate at least one heating phase during the lower and middle Mesozoic while similar heating could not be observed in northern Switzerland. However, the FT-data in both regions show moderate to rapid cooling during the Cretaceous and Lower Eocene, which was followed by an Upper Eocene heating event. The software package GOCAD (Geological Objects Computer-Aided Design) was used to build a digital elevation model (DEM), which provide a new detailed view of these FT data sets. The model is located about 20 km east of Basel, Switzerland, and extends over an area of about 21km by 24 km and spans a vertical height difference of about 2 km. The data sets described above along with two additional FT analyses from the Buntsandstein which lies directly on the BF crystalline, were compiled and plotted at their topographic heights in the DEM. The FT central-ages (Galbraith & Laslett 1993) of this region range between 25 ± 2Ma and 98 ± 6.5 Ma. The topographic positions extend between −1412m at the Borehole Riniken and 960m in the BF with mean sea level as a reference. FT central-age isochron surfaces were drawn in order to visualize the thermal evolution within the model range. Because the FT central-ages also correspond to a closure temperature, these surfaces can also be considered an isotherm. The FT closure temperature of apatite is about 90±30°C (Laslett et al. 1987). Therefore each surface shows the position and shape of the ca. 90°C isotherm of a specific age. This 3-D model points out an important difference in the thermal evolution of the BF und the TJ. The vertical distance between the isothermal surfaces increases from north to south. Between 90Ma and 60Ma the ca. 90°C isotherm drops at the Kaisten borehole by 1000m while in the same time span in the BF a lowering of the same isotherm by 300m can be observed. In the eastern part of the model this feature is not as marked as in the west but nevertheless it is observable. To explain this entirely different thermal evolution it is necessary to turn to the tectonic and other geological features of the region. South of the exposed BF crystalline and beneath the TJ there lies an old Variscan structure: the Permo-Carboniferous trough (PCT). This trough strikes in WSWENE direction and extends from Lake Constance to the Bresse Graben and contains up to 6000m of Palaeozoic sediments. Additionally, some Variscan fault structures strike in WNW–ESE direction and cut both the BF an the PCT, for example the Eggberg Fault and the Vorwald Fault. Beside the tectonic structures the hydrological characteristics played an important role during the palaeo-thermal evolution. Circulating hot fluids controlled the thermal pattern. Variscan faults were often reactivated during the Mesozoic (e.g. Wetzel et al. 2003) and also during the formation of the Upper Rhine Graben. (e.g. Illies 1967) These faults are the major water-conducting features in the crystalline basement of the BF, joints and fracture networks are tributaries. Below the aquifers within the Mesozoic of the TJ, the PCT trough sediments predominantly act as an aquitard. Only the border faults of the trough were important pathways for fluids (Thury 1994). Considering the Mesozoic sedimentological history of the region it is unlikely that fault movements are responsible for the different palaeo-thermal pattern of the BF and the TJ. Only different magnitudes of heat flow caused by hydrothermal circulating fluids can explain the ‘warm’ BF crystalline in comparison to the ‘cold’ basement of the TJ at the transition between the Mesozoic and Tertiary.conferenc

First experimental evidence suggests use of glucobrassicin as source of auxin in drought-stressed Arabidopsis thaliana

The synthesis of indole-3-acetonitrile (IAN) from the indolic glucosinolate (iGSL) glucobrassicin (GB) is a unique trait of members of the Brassicales. To assess the contribution of this pathway to indole-3-acetic acid (IAA) synthesis under stress conditions, drought stress (DS) experiments with Arabidopsis thaliana were performed in vitro. Analysis of GSLs in DS plants revealed higher contents of GB in shoots and roots compared to control plants. Deuterium incorporation experiments showed the highest turnover of GB compared to all other GSLs during drought conditions. Evidence suggests the involvement of the thioglucosidase BGLU18 in the degradation of GB. The nitrile specifier proteins NSP1 and NSP5 are known to direct the GSL hydrolysis towards formation of IAN. Nitrilases like NIT2 are able to subsequently synthesize IAA from IAN. Expression of BGLU18, NSP1, NSP5 and NIT2 and contents of GB, IAN and IAA were significantly elevated in DS plants compared to control plants suggesting the increased use of GB as IAA source. Significantly higher contents of reactive oxygen species in DS bglu18 and epithionitrile specifier protein (esp) mutants compared to Col-0 indicate higher stress levels in these mutants highlighting the need for both proteins in DS plants. Furthermore, GB accumulation in leaves was higher in both mutants during DS when compared to Col-0 indicating enhanced synthesis of GB due to a lack of breakdown products. This work provides the first evidence for the breakdown of iGSLs to IAN which seems to be used for synthesis of IAA in DS A. thaliana plants

A common histone modification code on C4 genes in maize and its conservation in sorghum and setaria Italica

C4 photosynthesis evolvedmore than 60 times independently in different plant lineages. Each time,multiple genes were recruited into C4 metabolism. The corresponding promoters acquired new regulatory features such as high expression, light induction, or cell typespecific expression in mesophyll or bundle sheath cells. We have previously shown that histone modifications contribute to the regulation of the model C4 phosphoenolpyruvate carboxylase (C4-Pepc) promoter in maize (Zea mays). We here tested the light- and cell type-specific responses of three selected histone acetylations and two histone methylations on five additional C4 genes (C4-Ca, C4- Ppdk, C4-Me, C4-Pepck, and C4-RbcS2) in maize. Histone acetylation and nucleosome occupancy assays indicated extended promoter regions with regulatory upstream regions more than 1,000 bp from the transcription initiation site for most of these genes. Despite any detectable homology of the promoters on the primary sequence level, histone modification patterns were highly coregulated. Specifically, H3K9ac was regulated by illumination, whereas H3K4me3 was regulated in a cell type-specific manner. We further compared histone modifications on the C4-Pepc and C4-Me genes from maize and the homologous genes from sorghum (Sorghum bicolor) and Setaria italica.Whereas sorghum and maize share a common C4 origin, C4 metabolism evolved independently in S. italica. The distribution of histone modifications over the promoters differed between the species, but differential regulation of light-induced histone acetylation and cell type-specific histone methylation were evident in all three species. We propose that a preexisting histone code was recruited into C4 promoter control during the evolution of C4 metabolism. © 2013 American Society of Plant Biologists. All Rights Reserved

The Diurnal Rhythm of Brassica napus L. Influences Contents of Sulfur-Containing Defense Compounds and Occurrence of Vascular Occlusions during an Infection with Verticillium longisporum

Reduction in atmospheric sulfur and intensified agriculture have led to sulfur deficiency, often correlated with a higher susceptibility to pathogens. The spread of fungal pathogens, such as the soil-born Verticillium longisporum, was observed. Defense responses of infected plants are linked to sulfur-containing compounds including glucosinolates (GSLs). Some pathogens infect their hosts at specific time periods during the day. To investigate the relation of sulfur-containing metabolites with diurnal effects of infection time points, Brassica napus plants cultivated at two different sulfur supplies, were infected with V. longisporum at four different time points during the day. It was demonstrated that 3, 7 and 14 days after inoculation the infected plants differed in their infection rate depending on the time point of infection. Additionally, infected plants had higher contents of sulfur-containing metabolites, such as specific GSLs, in comparison to non-infected plants. Sufficient sulfur fertilization was always reflected in higher contents of sulfur-containing compounds as well as a lower rate of infection compared to sulfur-deprived plants. On the microscopic level vascular occlusions in the hypocotyl were visible and the amount was dependent on the time point of infection. The results might be used to optimize sulfur fertilization to reduce susceptibility to V. longisporum

Немецкий язык как компонент языковой ситуации в Чаинском районе Томской области

Настоящая статья актуализирует промежуточные результаты социолингвистического анкетирования на территории Чаинского района Томской области, являющейся одним из мест дисперсного проживания потомков этнических немцев, подвергнутых принудительной депортации из различных населенных пунктов Саратовской области в Сибирь в 40-ые годы 20 века

Cardiac Glucose and Fatty Acid Transport After Experimental Mono- and Polytrauma

OBJECTIVE The aim of this study was to define the influence of trauma on cardiac glucose and fatty acid transport. The effects were investigated in vivo in a porcine mono- and polytrauma model and in vitro in human cardiomyocytes, which were treated simultaneously with different inflammatory substances, mimicking post-traumatic inflammatory conditions. METHODS AND RESULTS In the porcine fracture- and polytrauma model, blood glucose concentrations were measured by blood gas analysis during an observation period of 72 h. The expression of cardiac glucose and fatty acid transporters in the left ventricle was determined by RT-qPCR and immunofluorescence. Cardiac and hepatic glycogen storage was examined. Furthermore, human cardiomyocytes were exposed to a defined trauma-cocktail and the expression levels of glucose- and fatty acid transporters were determined. Early after polytrauma, hyperglycaemia was observed. After 48 h and 72 h, pigs with fracture- and polytrauma developed hypoglycaemia. The propofol demand significantly increased post trauma. The hepatic glycogen concentration was reduced 72 h after trauma. Cardiac glucose and fatty acid transporters changed in both trauma models in vivo as well as in vitro in human cardiomyocytes in presence of proinflammatory mediators. CONCLUSIONS Monotrauma as well as polytrauma changed the cardiac energy transport by altering the expression of glucose and fatty acid transporters. In vitro data suggest that human cardiomyocytes shift to a state alike myocardial hibernation preferring glucose as primary energy source in order to maintain cardiac function