880 research outputs found
Complexity and robustness of the flavonoid transcriptional regulatory network revealed by comprehensive analyses of MYB-bHLH-WDR complexes and their targets in Arabidopsis seed.
In Arabidopsis thaliana, proanthocyanidins (PAs) accumulate in the innermost cell layer of the seed coat (i.e. endothelium, chalaza and micropyle). The expression of the biosynthetic genes involved relies on the transcriptional activity of R2R3-MYB and basic helix-loop-helix (bHLH) proteins which form ternary complexes (\u27MBW\u27) with TRANSPARENT TESTA GLABRA1 (TTG1) (WD repeat protein). The identification of the direct targets and the determination of the nature and spatio-temporal activity of these MBW complexes are essential steps towards a comprehensive understanding of the transcriptional mechanisms that control flavonoid biosynthesis. In this study, various molecular, genetic and biochemical approaches were used. Here, we have demonstrated that, of the 12 studied genes of the pathway, only dihydroflavonol-4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX), BANYULS (BAN), TRANSPARENT TESTA 19 (TT19), TT12 and H(+) -ATPase isoform 10 (AHA10) are direct targets of the MBW complexes. Interestingly, although the TT2-TT8-TTG1 complex plays the major role in developing seeds, three additional MBW complexes (i.e. MYB5-TT8-TTG1, TT2-EGL3-TTG1 and TT2-GL3-TTG1) were also shown to be involved, in a tissue-specific manner. Finally, a minimal promoter was identified for each of the target genes of the MBW complexes. Altogether, by answering fundamental questions and by demonstrating or invalidating previously made hypotheses, this study provides a new and comprehensive view of the transcriptional regulatory mechanisms controlling PA and anthocyanin biosynthesis in Arabidopsis
A new system for fast and quantitative analysis of heterologous gene expression in plants
Large-scale analysis of transcription factor–cis-acting element interactions in plants, or the dissection of complex transcriptional regulatory mechanisms, requires rapid, robust and reliable systems for the quantification of gene expression.Here, we describe a new system for transient expression analysis of transcription factors, which takes advantage of the fast and easy production and transfection of Physcomitrella patens protoplasts, coupled to flow cytometry quantification of a fluorescent protein (green fluorescent protein). Two small-sized and high-copy Gateway® vectors were specifically designed, although standard binary vectors can also be employed. As a proof of concept, the regulation of BANYULS (BAN), a key structural gene involved in proanthocyanidin biosynthesis in Arabidopsis thaliana seeds, was used. In P. patens, BAN expression is activated by a complex composed of three proteins (TT2/AtMYB123, TT8/bHLH042 and TTG1), and is inhibited by MYBL2, a transcriptional repressor, as in Arabidopsis. Using this approach, two new regulatory sequences that are necessary and sufficient for specific BAN expression in proanthocyanidin-accumulating cells were identified. This one hybrid-like plant system was successfully employed to quantitatively assess the transcriptional activity of four regulatory proteins, and to identify their target recognition sites on the BAN promoter
Feature integration in natural language concepts
Two experiments measured the joint influence of three key sets of semantic features on the frequency with which artifacts (Experiment 1) or plants and creatures (Experiment 2) were categorized in familiar categories. For artifacts, current function outweighed both originally intended function and current appearance. For biological kinds, appearance and behavior, an inner biological function, and appearance and behavior of offspring all had similarly strong effects on categorization. The data were analyzed to determine whether an independent cue model or an interactive model best accounted for how the effects of the three feature sets combined. Feature integration was found to be additive for artifacts but interactive for biological kinds. In keeping with this, membership in contrasting artifact categories tended to be superadditive, indicating overlapping categories, whereas for biological kinds, it was subadditive, indicating conceptual gaps between categories. It is argued that the results underline a key domain difference between artifact and biological concepts
Extensive Spectroscopy and Photometry of the Type IIP Supernova 2013ej
We present extensive optical (, , and open CCD) and
near-infrared () photometry for the very nearby Type IIP SN ~2013ej
extending from +1 to +461 days after shock breakout, estimated to be MJD
. Substantial time series ultraviolet and optical spectroscopy
obtained from +8 to +135 days are also presented. Considering well-observed SNe
IIP from the literature, we derive bolometric calibrations from
and unfiltered measurements that potentially reach 2\% precision with a
color-dependent correction. We observe moderately strong Si II
as early as +8 days. The photospheric velocity () is
determined by modeling the spectra in the vicinity of Fe II
whenever observed, and interpolating at photometric epochs based on a
semianalytic method. This gives km s at +50
days. We also observe spectral homogeneity of ultraviolet spectra at +10--12
days for SNe IIP, while variations are evident a week after explosion. Using
the expanding photosphere method, from combined analysis of SN 2013ej and SN
2002ap, we estimate the distance to the host galaxy to be
Mpc, consistent with distance estimates from other methods. Photometric and
spectroscopic analysis during the plateau phase, which we estimated to be
days long, yields an explosion energy of
ergs, a final pre-explosion progenitor mass of ~M and a
radius of ~R. We observe a broken exponential profile beyond
+120 days, with a break point at + days. Measurements beyond this
break time yield a Ni mass of ~M.Comment: 29 pages, 23 figures, 15 tables, Published in The Astrophisical
Journa
The effects of stand characteristics on the understory vegetation in Quercus petraea and Q. cerris dominated forests
The shelterwood system used in Hungary has many effects on the composition and structure of the herb layer. The aim of our study was to identify the main variables that affect the occurence of herbs and seedlings in Turkey oak-sessile oak (Quercus cerris and Q. petraea) stands. The study was carried out in the Bükk mountains, Hungary. 122 sampling plots were established in 50-150 year old oak forests, where we studied the species composition and structure of the understorey and overstorey. The occurence of herbs was affected by canopy closure, the heterogenity and patchiness of the stand, the slope and the east-west component of the aspect. The composition of saplings was significantly explained by the ratio of the two major oak species in the stand and the proximity of the adult plants. An important result for forest management was that sessile oaks were able to regenerate almost only where they were dominant in the overstorey
The role of collective narcissism in populist attitudes and the collapse of democracy in Hungary
What are the psychological processes responsible for the recent spread of populist political systems and movements? All political systems essentially reflect the mental representations of their populations, and collective narcissism has recently emerged as a contributing factor in the rise of populism. This article presents two studies examining the role of collective narcissism in predicting populist attitudes and voting intentions in Hungary. Hungary offers a particularly important case study of state-sponsored populism and illiberalism in Europe, as this country has gone furthest in undermining democratic principles and practices within the EU. To establish the pervasive role of collective narcissism we first review the historical evidence, survey research, and narrative analyses of Hungarian political representations. We then present two empirical studies where we predicted and found that collective narcissism was a significant predictor of negative attitudes toward the EU (Study 1), conservatism, and support for the ruling populist party (Studies 1 and 2). Collective narcissism predicted these variables independently from other factors, such as in-group positivity or perceived relative deprivation. However, once conservatism was controlled for the effects of collective narcissism faded out in some cases. The results nevertheless indicate that collective narcissism plays important role in promoting populist politics. The implications of these findings for understanding the psychological appeal of populism and illiberalism are discussed
Dynamic Grouping of Hippocampal Neural Activity During Cognitive Control of Two Spatial Frames
Hippocampal neurons represent two concurrent streams of spatial information by transiently organizing into subpopulations of coactive neurons and can reflect the most behaviorally relevant information at any given time
Pollination and dispersal trait spectra recover faster than the growth form spectrum during spontaneous succession in sandy old‐fields
Question: Spontaneous succession is the most natural and cost‐effective solution for grassland restoration. However, little is known about the time required for the recovery of grassland functionality, i.e., for the recovery of reproductive and vegetative processes typical of pristine grasslands. Since these processes operate at different scales, we addressed the question: do reproductive and vegetative processes require different recovery times during spontaneous succession?
Location: Kiskunság sand region (Central Hungary).
Methods: As combinations of plant traits can be used to highlight general patterns in ecological processes, we compared reproductive (pollination‐ and dispersal‐related) and vegetative (growth form) traits between recovered grasslands of different age (<10 years old; 10–20 years old; 20–40 years old) and pristine grasslands.
Results: During spontaneous succession, the reproductive trait spectra became similar to those of pristine grasslands earlier than the vegetative ones. In arable land abandoned for 10 years, pollination‐ and dispersal‐related trait spectra did not show significant difference to those of pristine grasslands; anemophily and anemochory were the prevailing strategies. Contrarily, significant differences in the growth form spectrum could be observed even after 40 years of abandonment; in recovered grasslands erect leafy species prevailed, while the fraction of dwarf shrubs and tussock‐forming species was significantly lower than in pristine grasslands.
Conclusions: The recovery of the ecological processes of pristine grasslands might require different amounts of time, depending on the spatial scale at which they operate. The reproductive trait spectra recovered earlier than the vegetative one, since reproductive attributes first determine plant species sorting at the regional level towards their respective habitats. The recovery of the vegetative trait spectrum needs more time as vegetative‐based interactions operate on a smaller spatial scale. Thus, vegetative traits might be more effective in the long‐term assessment of restoration success than the reproductive ones
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