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640 results on '"Novak, Ondrej"'

1. High power single crystal KTA optical parametric amplifier for efficient 1.4-3.5 $\mu$m mid-IR radiation generation

Author

Csanaková, Bianka, Novák, Ondřej, Roškot, Lukáš, Mužík, Jiří, Smrž, Martin, Jelínková, Helena, and Mocek, Tomáš

Subjects
Physics - Optics
Abstract

In this paper, we present a single crystal, KTA (potassium titanyl-arsenate, KTiOAsO$_4$) based picosecond optical parametric amplifier pumped by an in-house built 1030 nm Yb:YAG thin-disk laser, capable of tunability from 1.46 to 3.5 $\mu$m, operating at 90 kHz, with high average power in the signal and idler beams. The highest output power of 8.9 W was reached for the 1750 nm signal beam with 19% conversion efficiency and the respective 2500 nm idler beam power was 6.2 W with 13% efficiency. The highest combined signal and idler mid-IR power was obtained at 17 W at the 2060 nm wavelength degeneracy point., Comment: 8 pages, 14 figures

Published
2024
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3. Cytokinins regulate spatially specific ethylene production to control root growth in Arabidopsis

Author

Yamoune, Amel, Zdarska, Marketa, Depaepe, Thomas, Rudolfova, Anna, Skalak, Jan, Berendzen, Kenneth Wayne, Mira-Rodado, Virtudes, Fitz, Michael, Pekarova, Blanka, Nicolas Mala, Katrina Leslie, Tarr, Paul, Spackova, Eliska, Tomovicova, Lucia, Parizkova, Barbora, Franczyk, Abigail, Kovacova, Ingrid, Dolgikh, Vladislav, Zemlyanskaya, Elena, Pernisova, Marketa, Novak, Ondrej, Meyerowitz, Elliot, Harter, Klaus, Van Der Straeten, Dominique, and Hejatko, Jan

Published
2024
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11. Circular displacement current induced anomalous magneto-optical effects in high index Mie resonators

Author

Xia, Shuang, Ignatyeva, Daria, Liu, Qing, Wang, Hanbin, Yang, Weihao, Qin, Jun, Chen, Yiqin, Duan, Huigao, Luo, Yi, Novak, Ondrej, Veis, Martin, Deng, Longjiang, Belotelov, Vladimir I., and Bi, Lei

Subjects
Physics - Optics
Abstract

Dielectric Mie nanoresonators showing strong light-matter interaction at the nanoscale may enable new functionality in photonic devices. Recently, strong magneto-optical effects have been observed in magneto-optical nanophotonic devices due to the electromagnetic field localization. However, most reports so far have been focused on the enhancement of conventional magneto-optical effects. Here, we report the observation of circular displacement current induced anomalous magneto-optical effects in high-index-contrast Si/Ce:YIG/YIG/SiO2 Mie resonators. In particular, giant modulation of light intensity in transverse magnetic configuration up to 6.4 % under s-polarized incidence appears, which is non-existent in planar magneto-optical thin films. Apart from that, we observe a large rotation of transmitted light polarization in the longitudinal magnetic configuration under near normal incidence conditions, which is two orders of magnitude higher than for a planar magneto-optical thin film. These phenomena are essentially originated from the unique circular displacement current when exciting the magnetic resonance modes in the Mie resonators, which changes the incident electric field direction locally. Our work indicates an uncharted territory of light polarization control based on the complex modal profiles in all-dielectric magneto-optical Mie resonators and metasurfaces, which opens the door for versatile control of light propagation by magnetization for a variety of applications in vectoral magnetic field and biosensing, free space non-reciprocal photonic devices, magneto-optical imaging and optomagnetic memories.

Published
2021

13. Hormonal responses of rice to organ-targeted cold stress

Author

Jarošová, Jana, Prerostova, Sylva, Černý, Martin, Dobrev, Petre, Gaudinova, Alena, Knirsch, Vojtech, Kobzová, Eva, Müller, Karel, Fiala, Roman, Benczúr, Kinga, Szalai, Gabriella, Novák, Jan, Brzobohatý, Břetislav, Novak, Ondrej, and Vankova, Radomira

Published
2024
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25. AAV ablates neurogenesis in the adult murine hippocampus

Author

Johnston, Stephen, Parylak, Sarah, Kim, Stacy, Mac, Nolan, Lim, Christina, Gallina, Iryna, Bloyd, Cooper, Newberry, Alexander, Saavedra, Christian D, Novak, Ondrej, Goncalves, J Tiago, Gage, Fred H, and Shtrahman, Matthew

Subjects
Biotechnology, Stem Cell Research, Neurosciences, Stem Cell Research - Nonembryonic - Non-Human, Gene Therapy, Regenerative Medicine, Genetics, Development of treatments and therapeutic interventions, 5.2 Cellular and gene therapies, Adult, Animals, Cell Death, Cell Proliferation, Central Nervous System, Dependovirus, Genetic Therapy, Genetic Vectors, Hippocampus, Humans, Inflammation, Male, Mice, Mice, Inbred C57BL, Neural Stem Cells, Neurogenesis, Neurons, adeno-associated virus, adult neurogenesis, dentate gyrus, gene therapy, hippocampus, mouse, neural progenitor cell, neuroscience, regenerative medicine, stem cells, Biochemistry and Cell Biology
Abstract

Recombinant adeno-associated virus (rAAV) has been widely used as a viral vector across mammalian biology and has been shown to be safe and effective in human gene therapy. We demonstrate that neural progenitor cells (NPCs) and immature dentate granule cells (DGCs) within the adult murine hippocampus are particularly sensitive to rAAV-induced cell death. Cell loss is dose dependent and nearly complete at experimentally relevant viral titers. rAAV-induced cell death is rapid and persistent, with loss of BrdU-labeled cells within 18 hr post-injection and no evidence of recovery of adult neurogenesis at 3 months post-injection. The remaining mature DGCs appear hyperactive 4 weeks post-injection based on immediate early gene expression, consistent with previous studies investigating the effects of attenuating adult neurogenesis. In vitro application of AAV or electroporation of AAV2 inverted terminal repeats (ITRs) is sufficient to induce cell death. Efficient transduction of the dentategyrus (DG)- without ablating adult neurogenesis- can be achieved by injection of rAAV2-retro serotyped virus into CA3. rAAV2-retro results in efficient retrograde labeling of mature DGCs and permits in vivo two-photon calcium imaging of dentate activity while leaving adult neurogenesis intact. These findings expand on recent reports implicating rAAV-linked toxicity in stem cells and other cell types and suggest that future work using rAAV as an experimental tool in the DG and as a gene therapy for diseases of the central nervous system should be carefully evaluated.

Published
2021

29. A genetically encoded fluorescent sensor for in vivo imaging of GABA

Author

Marvin, Jonathan S, Shimoda, Yoshiteru, Magloire, Vincent, Leite, Marco, Kawashima, Takashi, Jensen, Thomas P, Kolb, Ilya, Knott, Erika L, Novak, Ondrej, Podgorski, Kaspar, Leidenheimer, Nancy J, Rusakov, Dmitri A, Ahrens, Misha B, Kullmann, Dimitri M, and Looger, Loren L

Subjects
Biological Sciences, Neurosciences, Bioengineering, 1.1 Normal biological development and functioning, Underpinning research, Neurological, Anesthesia, Animals, Animals, Genetically Modified, Biosensing Techniques, Brain, Female, Green Fluorescent Proteins, Hippocampus, Male, Mice, Mice, Inbred C57BL, Molecular Imaging, Neurons, Rats, Rats, Sprague-Dawley, Seizures, Zebrafish, gamma-Aminobutyric Acid, Technology, Medical and Health Sciences, Developmental Biology, Biological sciences
Abstract

Current techniques for monitoring GABA (γ-aminobutyric acid), the primary inhibitory neurotransmitter in vertebrates, cannot follow transients in intact neural circuits. To develop a GABA sensor, we applied the design principles used to create the fluorescent glutamate receptor iGluSnFR. We used a protein derived from a previously unsequenced Pseudomonas fluorescens strain and performed structure-guided mutagenesis and library screening to obtain intensity-based GABA sensing fluorescence reporter (iGABASnFR) variants. iGABASnFR is genetically encoded, detects GABA release evoked by electric stimulation of afferent fibers in acute brain slices and produces readily detectable fluorescence increases in vivo in mice and zebrafish. We applied iGABASnFR to track mitochondrial GABA content and its modulation by an anticonvulsant, swimming-evoked, GABA-mediated transmission in zebrafish cerebellum, GABA release events during interictal spikes and seizures in awake mice, and found that GABA-mediated tone decreases during isoflurane anesthesia.

Published
2019

30. Surveillance of cell wall diffusion barrier integrity modulates water and solute transport in plants.

Author

Wang, Peng, Calvo-Polanco, Monica, Reyt, Guilhem, Barberon, Marie, Champeyroux, Chloe, Santoni, Véronique, Maurel, Christophe, Franke, Rochus B, Ljung, Karin, Novak, Ondrej, Geldner, Niko, Boursiac, Yann, and Salt, David E

Abstract

The endodermis is a key cell layer in plant roots that contributes to the controlled uptake of water and mineral nutrients into plants. In order to provide such functionality the endodermal cell wall has specific chemical modifications consisting of lignin bands (Casparian strips) that encircle each cell, and deposition of a waxy-like substance (suberin) between the wall and the plasma membrane. These two extracellular deposits provide control of diffusion enabling the endodermis to direct the movement of water and solutes into and out of the vascular system in roots. Loss of integrity of the Casparian strip-based apoplastic barrier is sensed by the leakage of a small peptide from the stele into the cortex. Here, we report that such sensing of barrier integrity leads to the rebalancing of water and mineral nutrient uptake, compensating for breakage of Casparian strips. This rebalancing involves both a reduction in root hydraulic conductivity driven by deactivation of aquaporins, and downstream limitation of ion leakage through deposition of suberin. These responses in the root are also coupled to a reduction in water demand in the shoot mediated by ABA-dependent stomatal closure.

Published
2019

33. Cytokinin‐deficient Chlamydomonas reinhardtii CRISPR‐Cas9 mutants show reduced ability to prime resistance of tobacco against bacterial infection

Author

Sandor, Roman, primary, Wagh, Sopan Ganpatrao, additional, Kelterborn, Simon, additional, Großkinsky, Dominik K., additional, Novak, Ondrej, additional, Olsen, Niels, additional, Paul, Bichitra, additional, Petřík, Ivan, additional, Wu, Shujie, additional, Hegemann, Peter, additional, Strnad, Miroslav, additional, Červený, Jan, additional, and Roitsch, Thomas, additional

Published
2024
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38. In situ seasonal patterns of root auxin concentrations and meristem length in an arctic sedge

Author

Blume-Werry, Gesche, Semenchuk, Philipp, Ljung, Karin, Milbau, Ann, Novak, Ondrej, Olofsson, Johan, Brunoni, Federica, Blume-Werry, Gesche, Semenchuk, Philipp, Ljung, Karin, Milbau, Ann, Novak, Ondrej, Olofsson, Johan, and Brunoni, Federica

Abstract

Seasonal dynamics of root growth play an important role in large-scale ecosystem processes; they are largely governed by growth regulatory compounds and influenced by environmental conditions. Yet, our knowledge about physiological drivers of root growth is mostly limited to laboratory-based studies on model plant species. We sampled root tips of Eriophorum vaginatum and analyzed their auxin concentrations and meristem lengths biweekly over a growing season in situ in a subarctic peatland, both in surface soil and at the permafrost thawfront. Auxin concentrations were almost five times higher in surface than in thawfront soils and increased over the season, especially at the thawfront. Surprisingly, meristem length showed an opposite pattern and was almost double in thawfront compared with surface soils. Meristem length increased from peak to late season in the surface soils but decreased at the thawfront. Our study of in situ seasonal dynamics in root physiological parameters illustrates the potential for physiological methods to be applied in ecological studies and emphasizes the importance of in situ measurements. The strong effect of root location and the unexpected opposite patterns of meristem length and auxin concentrations likely show that auxin actively governs root growth to ensure a high potential for nutrient uptake at the thawfront.

Published
2024
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39. Cytokinin-deficient Chlamydomonas reinhardtii CRISPR-Cas9 mutants show reduced ability to prime resistance of tobacco against bacterial infection

Author

Sandor, Roman, Wagh, Sopan Ganpatrao, Kelterborn, Simon, Großkinsky, Dominik K., Novak, Ondrej, Olsen, Niels, Paul, Bichitra, Petřík, Ivan, Wu, Shujie, Hegemann, Peter, Strnad, Miroslav, Červený, Jan, Roitsch, Thomas, Sandor, Roman, Wagh, Sopan Ganpatrao, Kelterborn, Simon, Großkinsky, Dominik K., Novak, Ondrej, Olsen, Niels, Paul, Bichitra, Petřík, Ivan, Wu, Shujie, Hegemann, Peter, Strnad, Miroslav, Červený, Jan, and Roitsch, Thomas

Abstract

Although microalgae have only recently been recognized as part of the plant and soil microbiome, their application as biofertilizers has a tradition in sustainable crop production. Under consideration of their ability to produce the plant growth-stimulating hormone cytokinin (CK), known to also induce pathogen resistance, we have assessed the biocontrol ability of CK-producing microalgae. All pro- and eukaryotic CK-producing microalgae tested were able to enhance the tolerance of tobacco against Pseudomonas syringae pv. tabaci (PsT) infection. Since Chlamydomonas reinhardtii (Cre) proved to be the most efficient, we functionally characterized its biocontrol ability. We employed the CRISPR-Cas9 system to generate the first knockouts of CK biosynthetic genes in microalgae. Specifically, we targeted Cre Lonely Guy (LOG) and isopentenyltransferase (IPT) genes, the key genes of CK biosynthesis. While Cre wild-type exhibits a strong protection, the CK-deficient mutants have a reduced ability to induce plant defence. The degree of protection correlates with the CK levels, with the IPT mutants showing less protection than the LOG mutants. Gene expression analyses showed that Cre strongly stimulates tobacco resistance through defence gene priming. This study functionally verifies that Cre primes defence responses with CK, which contributes to the robustness of the effect. This work contributes to elucidate microalgae-mediated plant defence priming and identifies the role of CKs. In addition, these results underscore the potential of CK-producing microalgae as biologicals in agriculture by combining biofertilizer and biocontrol ability for sustainable and environment-friendly crop management.

Published
2024

40. Spider mite infestation triggers coordinated hormonal trade‐offs enabling plant survival with a fitness cost.

Author

Garcia, Alejandro, Talavera‐Mateo, Lucia, Petrik, Ivan, Oklestkova, Jana, Novak, Ondrej, and Santamaria, M. Estrella

Subjects
MITE infestations, TWO-spotted spider mite, PEST control, PLANT adaptation, SEED viability
Abstract

Tetranychus urticae is an important pest that causes severe damage to a wide variety of plants and crops, leading to a substantial productivity loss. Previous research has been focused on plant defence response to T. urticae to improve plant resistance. However, plant growth, development and reproduction throughout the infestation process have not been previously studied. Through physiological, biochemical, transcriptomic and hormonomic evaluation, we uncover the molecular mechanisms directing the defence‐growth trade‐off established in Arabidopsis upon T. urticae infestation. Upon mite attack, plants suffer an adaptation process characterized by a temporal separation between the defence and growth responses. Jasmonic and salicylic acids regulate the main defence responses in combination with auxin and abscisic acid. However, while the reduction of both auxin signalling and gibberellin, cytokinin and brassinosteroid biosynthesis lead to initial growth arrest, increasing levels of growth hormones at later stages enables growth restart. These alterations lead to a plant developmental delay that impacts both seed production and longevity. We demonstrate that coordinated trade‐offs determine plant adaptation and survival, revealing mite infestation has a long‐lasting effect negatively impacting seed viability. This study provides additional tools to design pest management strategies that improve resistance without penalty in plant fitness. [ABSTRACT FROM AUTHOR]

Published
2024
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46. HISTONE DEACETYLASE 9 stimulates auxin-dependent thermomorphogenesis in Arabidopsis thaliana by mediating H2A.Z depletion

Author

van der Woude, Lennard C., Perrella, Giorgio, Snoek, Basten L., van Hoogdalem, Mark, Novák, Ondřej, van Verk, Marcel C., van Kooten, Heleen N., Zorn, Lennert E., Tonckens, Rolf, Dongus, Joram A., Praat, Myrthe, Stouten, Evelien A., Proveniers, Marcel C. G., Vellutini, Elisa, Patitaki, Eirini, Shapulatov, Umidjon, Kohlen, Wouter, Balasubramanian, Sureshkumar, Ljung, Karin, van der Krol, Alexander R., Smeekens, Sjef, Kaiserli, Eirini, and van Zanten, Martijn

Published
2019

49. Selective auxin agonists induce specific AUX/IAA protein degradation to modulate plant development

Author

Vain, Thomas, Raggi, Sara, Ferro, Noel, Barange, Deepak Kumar, Kieffer, Martin, Ma, Qian, Doyle, Siamsa M., Thelander, Mattias, Pařízková, Barbora, Novák, Ondřej, Ismail, Alexandre, Enquist, Per-Anders, Rigal, Adeline, Łangowska, Małgorzata, Harborough, Sigurd Ramans, Zhang, Yi, Ljung, Karin, Callis, Judy, Almqvist, Fredrik, Kepinski, Stefan, Estelle, Mark, Pauwels, Laurens, and Robert, Stéphanie

Published
2019

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