scholarly journals Phototropin-mediated perception of light direction in leaves regulates blade flattening

2021 ◽  
Author(s):  
Martina Legris ◽  
Bogna Maria Szarzynska-Erden ◽  
Martine Trevisan ◽  
Laure Allenbach Petrolati ◽  
Christian Fankhauser
Keyword(s):  
Leaf Development ◽  
Light Response ◽  
Auxin Signaling ◽  
Kinase Substrate ◽  
Key Aspects ◽  
Light Capture ◽  
Signaling Components ◽  
Curled Leaves

Abstract One conserved feature among angiosperms is the development of flat thin leaves. This developmental pattern optimizes light capture and gas exchange. The blue light (BL) receptors phototropins are required for leaf flattening, with the null phot1phot2 mutant showing curled leaves in Arabidopsis (Arabidopsis thaliana). However, key aspects of their function in leaf development remain unknown. Here, we performed a detailed spatiotemporal characterization of phototropin function in Arabidopsis leaves. We found that phototropins perceive light direction in the blade, and, similar to their role in hypocotyls, they control the spatial pattern of auxin signaling, possibly modulating auxin transport, to ultimately regulate cell expansion. Phototropin signaling components in the leaf partially differ from hypocotyls. Moreover, the light response on the upper and lower sides of the leaf blade suggests a partially distinct requirement of phototropin signaling components on each side. In particular, NON PHOTOTROPIC HYPOCOTYL 3 showed an adaxial-specific function. In addition, we show a prominent role of PHYTOCHROME KINASE SUBSTRATE 3 in leaf flattening. Among auxin transporters, PIN-FORMED 3,4,7 and AUXIN RESISTANT 1 (AUX1)/LIKE AUXIN RESISTANT 1 (LAX1) are required for the response while ABCB19 has a regulatory role. Overall, our results show that directional BL perception by phototropins is a key aspect of leaf development, integrating endogenous and exogenous signals.

scholarly journals Phototropin-mediated perception of light direction in Arabidopsis leaves regulates blade flattening

2021 ◽  
Author(s):  
Christian Fankhauser ◽  
Martina Legris ◽  
Bogna Maria Szarzynska-Erden ◽  
Martine Trevisan ◽  
Laure Allenbach Petrolati
Keyword(s):  
Blue Light ◽  
Leaf Development ◽  
Leaf Blade ◽  
Light Response ◽  
Auxin Signaling ◽  
Kinase Substrate ◽  
Key Aspects ◽  
Light Capture ◽  
Signaling Components

One conserved feature among angiosperms is the development of flat thin leaves. This developmental pattern optimizes light capture and gas exchange for photosynthesis. The blue light receptors phototropins are required for leaf flattening, with the null phot1phot2 mutant showing downwards curled leaves in Arabidopsis. However, key aspects of their function in leaf development remain unknown. Here, we performed a detailed spatiotemporal characterization of phototropin function in Arabidopsis leaves. We found that phototropins perceive light direction in the leaf blade, and similar to their role in hypocotyls they control the spatial pattern of auxin signaling possibly modulating auxin transport, to ultimately regulate cell expansion. Phototropin signaling components in the leaf partially differ from hypocotyls. Moreover, the light response on the upper (adaxial) and lower (abaxial) sides of the leaf blade suggest a partially distinct requirement of phototropin signaling components on each side. In particular, NON PHOTOTROPIC HYPOCOTYL 3 (NPH3) showed an adaxial-specific function. In addition, we show a prominent role of PHYTOCHROME KINASE SUBSTRATE 3 (PKS3) in leaf flattening. Among the auxin transporters tested, PINs and AUX/LAX influence the response most prominently. Overall, our results show that directional blue light perception by the phototropins is a key aspect of leaf development, integrating endogenous and exogenous signals.

scholarly journals A synthetic approach reveals a highly sensitive maize auxin response circuit

2019 ◽  
Author(s):  
Román Ramos Báez ◽  
Yuli Buckley ◽  
Han Yu ◽  
Zongliang Chen ◽  
Andrea Gallavotti ◽  
...  
Keyword(s):  
Auxin Signaling ◽  
Synthetic Approach ◽  
Auxin Response ◽  
Auxin Receptor ◽  
Repressor Proteins ◽  
Highly Sensitive ◽  
Signaling Function ◽  
Wide Range ◽  
Signaling Components

Auxin plays a key role across all land plants in growth and developmental processes. Although auxin signaling function has diverged and expanded, differences in the molecular functions of signaling components have largely been characterized in Arabidopsis thaliana. Here, we used the Auxin Response Circuit recapitulated in Saccharomyces cerevisiae (ARCSc) system to functionally annotate maize auxin signaling components, focusing on genes expressed during development of ear and tassel inflorescences. All 16 maize Auxin (Aux)/Indole-3-Acetic Acid (IAA) repressor proteins are degraded in response to auxin, with rates that depended on both receptor and repressor identity. When fused to the maize TOPLESS (TPL) homolog RAMOSA1 ENHANCER LOCUS2 (REL2), maize Aux/IAAs were able to repress AUXIN RESPONSE FACTOR (ARF) transcriptional activity. A complete auxin response circuit comprised of all maize components, including ZmAFB2/3 b1 maize AUXIN SIGNALING F-BOX (AFB) receptor, was found to be fully functional. The ZmAFB2/3 b1 auxin receptor was found to be more sensitive to hormone than AtAFB2 and allowed for rapid circuit activation upon auxin addition. These results validate the conserved role of predicted auxin response genes in maize, as well as provide evidence that a synthetic approach can facilitate broader comparative studies across the wide range of species with sequenced genomes.

Regulation of the AMPK-related protein kinases by ubiquitination

2008 ◽  
Vol 411 (2) ◽  
pp. e9-e10 ◽  
Author(s):  
David M. Thomson ◽  
Marc D. H. Hansen ◽  
William W. Winder
Keyword(s):  
Deubiquitinating Enzyme ◽  
Polyubiquitin Chains ◽  
Kinase Substrate ◽  
Biochemical Journal ◽  
Substrate Level ◽  
Amp Activated Protein Kinase ◽  
And Control

How can a constitutively active ‘master’ kinase with numerous downstream targets preferentially phosphorylate one or more of these without influencing all simultaneously? How might such a system be switched off? The characterization of the role of deubiquitination in regulating the phosphorylation and activation of AMPK (AMP-activated protein kinase)-related kinases by LKB1 suggests a novel and interesting mechanism for conferring signal transduction specificity and control at the kinase substrate level. In this issue of the Biochemical Journal, Al-Hakim et al. show that the AMPK-related kinases NUAK1 (AMPK-related kinase 5) and MARK4 (microtubule-affinity-regulating kinase 4) are polyubiquitinated in vivo and that they serve as substrates of the deubiquitinating enzyme USP9X; furthermore, the first evidence is provided for regulation of AMPK-related kinase family members mediated via unusual Lys29/Lys33 polyubiquitin chains, rather than the more common Lys48/Lys63 linkages.

scholarly journals The Hoja loca1 Mutant and AUX/IAA Function in Maize

2020 ◽  
Author(s):  
A. E. Richardson ◽  
A. Sluis ◽  
S. Hake
Keyword(s):  
Functional Redundancy ◽  
Vital Role ◽  
Land Plants ◽  
Auxin Signaling ◽  
Organ Development ◽  
Loss Of Function ◽  
Plant Organ ◽  
Species Specific ◽  
Signaling Components

AbstractAuxin plays a vital role in plant organ development, influencing organ initiation and patterning across all axes. The diversity in auxin patterning results from changes in the activities and expression of auxin signaling components, including the AUX/IAA repressors. Higher land plants have multigene AUX/IAA families, which leads to functional redundancy and a lack of phenotype in loss of function mutants. Instead, dominant mutations, which prevent AUX/IAA degradation in response to auxin, have highlighted the importance of these proteins in organ development. Here we report a new dominant AUX/IAA mutant in maize, Hoja loca1 (Oja). Oja has a mutation in the degron motif of ZmIAA28 and affects aerial organ initiation and medio-lateral patterning in the leaf. These phenotypes contrast with other maize AUX/IAA mutants that affect the root or inflorescence only. Oja illustrates the role of auxin signaling in the tight coordination of phytomer unit development and provides evidence of species-specific sub-functionalization of the AUX/IAAs.One Line SummaryThe maize AUX/IAA ZmIAA38 is involved in phytomer coordination, aerial organ initiation and mediolateral patterning, and illustrates species specific sub-functionalization of the AUX/IAAs.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Consideraciones en torno a la reducción solipsista

1970 ◽  
Vol 11 ◽  
Author(s):  
Natalia Carolina Petrillo

ResumenEn el presente trabajo se intentará mostrar que la fenomenología no conduce a una postura solipsista. Para ello, se caracterizará en qué consiste el solipsismo. Luego, se intentará refutar a lo que se ha de llamar “solipsismo metafísico” y “solipsismo gnoseológico”, con el objetivo principal de poner de manifiesto el fundamento de motivación para la salida de la ficción solipsista.Palabras claves:Phenomenology – solipsim – empatía - HusserlAbstractWith the aim of showing that phenomenology does not lead in solipsism, I will first attempt a characterization of it. Then, I will attempt a refutation of the so-called “metaphysical” and “epistemological” solipsisms. Finally, the nature and role of Husserl´s solipsistic fiction is examined, and the grounds that motivate the overcoming of this standpoint are disclosed.key wordsFenomenología – solipsismo - empathy – Husserl

ART STUDIOS – A WAY TO DEVELOPE CHILDREN’S IMAGINATION

2020 ◽  
Vol 11 (1) ◽  
pp. 144-148
Author(s):  
Liuba Zlatkova ◽  
Keyword(s):  
Fairy Tale ◽  
Psychological Effects ◽  
Complete Product ◽  
The Arts ◽  
The Creation ◽  
Role Of Parents

The report describes the steps for creating a musical tale by children in the art studios of „Art Workshop“, Shumen. These studios are led by students volunteers related to the arts from pedagogical department of Shumen University, and are realized in time for optional activities in the school where the child studies. The stages of creating a complete product with the help of different arts are traced – from the birth of the idea; the creation of a fairy tale plot by the children; the characterization of the fairy-tale characters; dressing them in movement, song and speech; creating sets and costumes and creating a finished product to present on stage. The role of parents as a link and a necessary helper for children and leaders is also considered, as well as the positive psychological effects that this cooperation creates.

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