Signaling Overview of Plant Somatic Embryogenesis Méndez-Hernández, Hugo A; Ledezma-Rodríguez, Maharshi; Avilez-Montalvo, Randy N ...
Frontiers in plant science,
02/2019, Volume:
10
Journal Article
Peer reviewed
Open access
Somatic embryogenesis (SE) is a means by which plants can regenerate bipolar structures from a somatic cell. During the process of cell differentiation, the explant responds to endogenous stimuli, ...which trigger the induction of a signaling response and, consequently, modify the gene program of the cell. SE is probably the most studied plant regeneration model, but to date it is the least understood due to the unclear mechanisms that occur at a cellular level. In this review, the authors seek to emphasize the importance of signaling on plant SE, highlighting the interactions between the different plant growth regulators (PGR), mainly auxins, cytokinins (CKs), ethylene and abscisic acid (ABA), during the induction of SE. The role of signaling is examined from the start of cell differentiation through the early steps on the embryogenic pathway, as well as its relation to a plant's tolerance of different types of stress. Furthermore, the role of genes encoded to transcription factors (TFs) during the embryogenic process such as the
,
,
and
) genes, Arabinogalactan-proteins (AGPs),
and epigenetic factors is discussed.
Discrepancies regarding the coordination environment, donor atoms, nuclearity, and oxidation state of the active site of particulate methane monooxygenase (pMMO), a copper‐dependent enzyme capable of ...activating the strong C−H bond of methane, persist despite numerous structural and spectroscopic studies. To address the proposed mono‐ (CuII) or bimetallic (2CuI) nature of the so‐called CuB site, we report the bis(benzimidazole)‐based NMe−N,N’‐(1‐Me‐2‐CH2C7H4N2)2C6H4 ligand (N4) and its copper complexes. In the solid state Cu(N4)(ClO4)ClO4 features tetragonal geometry defined by the chelating ligand and an axial perchlorate; geometric and EPR parameters are very close to those reported for the CuB site. Attempts to obtain a dicopper(I) analog resulted in Cu(N4)CuCl2, based on spectroscopic, electrochemical, and ESI‐MS data. Although these results support the assignment of CuB as a monometallic site, air exposure of Cu(N4)CuCl2 leads to ligand oxidation in the structurally characterized Cu(N4=O)Cl, raising the possibility of distorted tetragonal Cu(I) centers activating O2 and oxidizing substrates, in C−H activation chemistry that may take place at CuB.
A tetradentate N‐ligand binds CuII in a geometric and electronic environment that resembles the properties of the CuB site of particulate Methane Monooxygenase (pMMO). Its CuI counterpart undergoes ligand oxidation during exposure to air, establishing the flexibility of the tetradentate scaffold that allows O2 activation and subsequent formation of a cupric amidato complex. This reactivity may be relevant for a reevaluation of the active site of pMMO, in which CuB has been relegated due to its “saturated” coordination environment.
Luminescent copper(I)‐based compounds have recently attracted much attention since they can reach very high emission quantum yields. Interestingly, Cu(I) clusters can also be emissive, and the ...extension from small molecules to larger architecture could represent the first step towards novel materials that could be obtained by programming the units to undergo self‐assembly. However, for Cu(I) compounds the formation of supramolecular systems is challenging due to the coordinative diversity of copper centers. This works shows that this diversity can be exploited in the construction of responsive systems. In detail, the changes in the emissive profile of different aggregates formed in water by phosphine‐thioether copper(I) derivatives were followed. Our results demonstrate that the self‐assembly and disassembly of Cu(I)‐based coordination polymeric nanoparticles (CPNs) is sensitive to solvent composition. The solvent‐induced changes are related to modifications in the coordination sphere of copper at the molecular level, which alters not only the emission profile but also the morphology of the aggregates. Our findings are expected to inspire the construction of smart supramolecular systems based on dynamic coordinative metal centers.
Stable copper(I) coordination polymer nanoparticles (CPNs) are self‐assembled in water and they display solvent composition‐responsive behavior that can be followed by emission of the aggregates. The dramatic differences in the emission energy and the morphology of the aggregates have been attributed to changes in the coordination sphere around the copper centers.
Two novel Iron (II) complexes featuring tetrapodal bis(benzimidazole)amino thio- and selenoether ligands (LS and LSe) were synthesized, characterized, and tested as electrocatalysts for the hydrogen ...evolution reaction. The bromide complexes Fe(LS,LSe)Br2 (1–2) are highly insoluble, but their DMSO solvates were characterized by single crystal X-ray diffraction, revealing an octahedral coordination environment that does not feature coordination of the chalcogen atoms. The corresponding triflate derivatives Fe(LS,LSe)(MeCN)3OTf2 (1c-2c) were employed for electrocatalytic proton reduction, with 1c exhibiting higher activity, thus suggesting that the thioether may participate as a more competent pendant ligand for proton transfer.
Bis(benzimidazole)-based Iron(II) complexes are competent Hydrogenase-inspired hydrogen evolution electrocatalysts that feature potentially proton-accepting intramolecular thio- and selenoethers groups. Display omitted
•Synthesis and characterization of benzimidazole-based Fe(II) complexes•Solid-state structures of Fe(II) complexes show non-coordinated selenoether groups.•Proton reduction evidenced by cyclic voltammetry.•Fe(I) proposed as active species in electrocatalytic hydrogen evolution.
We present the physical extent of C ii 158 m line-emitting gas from 46 star-forming galaxies at z = 4-6 from the ALMA Large Program to INvestigate C ii at Early Times (ALPINE). Using exponential ...profile fits, we measure the effective radius of the C ii line ( ) for individual galaxies and compare them with the rest-frame ultraviolet (UV) continuum ( ) from Hubble Space Telescope images. The effective radius exceeds by factors of ∼2-3, and the ratio of increases as a function of Mstar. We do not find strong evidence that the C ii line, rest-frame UV, and far-infrared (FIR) continuum are always displaced over 1 kpc scale from each other. We identify 30% of isolated ALPINE sources as having an extended C ii component over 10 kpc scales detected at 4.1 -10.9 beyond the size of rest-frame UV and FIR continuum. One object has tentative rotating features up to ∼10 kpc, where the 3D model fit shows the rotating C ii-gas disk spread over 4 times larger than the rest-frame UV-emitting region. Galaxies with the extended C ii line structure have high star formation rate, high stellar mass (Mstar), low Ly equivalent width, and more blueshifted (redshifted) rest-frame UV metal absorption (Ly line), as compared to galaxies without such extended C ii structures. Although we cannot rule out the possibility that a selection bias toward luminous objects may be responsible for such trends, the star-formation-driven outflow also explains all these trends. Deeper observations are essential to test whether the extended C ii line structures are ubiquitous to high-z star-forming galaxies.
Background and Aim
Abnormal cholesterol metabolism may contribute to the pathogenesis of non‐alcoholic steatohepatitis (NASH) and fibrosis. miR‐33 and miR‐144 regulate adenosine triphosphate binding ...cassette transporter (ABCA1) and other target genes involved in cholesterol efflux, fatty acid oxidation and inflammation. We explored relationships between non‐alcoholic fatty liver disease (NAFLD) and the hepatic expression of ABCA1/ABCG1, as well as other target genes regulated by miR‐33 (carnitine O‐octanoyltransferase, CROT and hydroxyacyl‐CoA‐dehydrogenase β‐subunit, HADHB) and miR‐144 (toll‐like receptor‐2, TLR2). Moreover, we evaluated whether the expression of these genes is correlated with miR‐33a/b and miR‐144 expression in Mexican individuals with morbid obesity.
Methods
Eighty‐four morbidly obese subjects undergoing bariatric surgery were included in this study. Liver biopsies were obtained to measure hepatic triglyceride and free cholesterol contents, as well as ABCA1, ABCG1, CROT, HADHB, TLR2, miR‐33a/b and miR‐144 expression.
Results
Hepatic free cholesterol content was significantly increased in NASH as compared to non‐NASH subjects, while ABCA1 and ABCG1 protein levels significantly decreased with NASH and fibrosis progression. The relative expression of miR‐33a and miR‐144 correlated inversely with ABCA1 but not with ABCG1 protein levels. Moreover, both miRNAs increased significantly in NASH individuals. miR‐33 target genes CROT and HADHB correlated inversely with miR‐33a. However, the expression of these genes was not associated with NASH.
Conclusions
miR‐33a/144 and their target gene ABCA1 may contribute to the pathogenesis of NASH in morbidly obese subjects.
We introduce a novel technique for designing color filter metasurfaces using a data-driven approach based on deep learning. Our innovative approach employs inverse design principles to identify ...highly efficient designs that outperform all the configurations in the dataset, which consists of 585 distinct geometries solely. By combining Multi-Valued Artificial Neural Networks and back-propagation optimization, we overcome the limitations of previous approaches, such as poor performance due to extrapolation and undesired local minima. Consequently, we successfully create reliable and highly efficient configurations for metasurface color filters capable of producing exceptionally vivid colors that go beyond the sRGB gamut. Furthermore, our deep learning technique can be extended to design various pixellated metasurface configurations with different functionalities.
The atypical arrival of pelagic
to the Mexican Caribbean beaches has caused considerable economic and ecological damage. Furthermore, it has raised new challenges for monitoring the coastlines. ...Historically, satellite remote-sensing has been used for
monitoring in the ocean; nonetheless, limitations in the temporal and spatial resolution of available satellite platforms do not allow for near real-time monitoring of this macro-algae on beaches. This study proposes an innovative approach for monitoring
on beaches using Crowdsourcing for imagery collection, deep learning for automatic classification, and geographic information systems for visualizing the results. We have coined this collaborative process "Collective View". It offers a geotagged dataset of images illustrating the presence or absence of
on beaches located along the northern and eastern regions in the Yucatan Peninsula, in Mexico. This new dataset is the largest of its kind in surrounding areas. As part of the design process for Collective View, three convolutional neural networks (LeNet-5, AlexNet and VGG16) were modified and retrained to classify images, according to the presence or absence of
. Findings from this study revealed that AlexNet demonstrated the best performance, achieving a maximum recall of 94%. These results are good considering that the training was carried out using a relatively small set of unbalanced images. Finally, this study provides a first approach to mapping the
distribution along the beaches using the classified geotagged images and offers novel insight into how we can accurately map the arrival of algal blooms along the coastline.
Optical nanoantennas, especially of the dipole type, have been theoretically and experimentally demonstrated by many research groups. Likewise, the plasmonic waveguides and optical circuits have ...experienced significant advances. In radio frequencies and microwaves a category of antenna known as dielectric resonator antenna (DRA), whose radiant element is a dielectric resonator (DR), has been designed for several applications, including satellite and radar systems. In this letter, we explore the possibilities and advantages to design nano DRAs (NDRAs), i. e., DRAs for nanophotonics applications. Numerical demonstrations showing the fundamental antenna parameters for a circular cylindrical NDRA type have been carried out for the short (S), conventional (C), and long (L) bands of the optical communication spectrum.
A novel hybrid multimode interferometer for sensing applications operating with both TE and TM polarizations simultaneously is proposed and numerically demonstrated. The simulations were performed ...assuming an operating wavelength of 633 nm with the goal of future use as a biosensor, but its applications extend beyond that area and could be adapted for any wavelength or application of interest. By designing the mutimode waveguide core with a low aspect ratio, the confinement characteristics of TE modes and TM modes become very distinct and their interaction with the sample in the sensing area becomes very different as well, resulting in high device sensitivity. In addition, an excitation structure is presented, that allows good control over power distribution between the desired modes while also restricting the power coupled to other undesired modes. This new hybrid TE/TM approach produced a bulk sensitivity per sensor length of 1.798 rad
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and a bulk sensitivity per sensor area of 2.140 rad
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, which represents a much smaller footprint when compared to other MMI sensors, contributing to a higher level of integration, while also opening possibilities for a new range of MMI devices.
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![The ALPINE-ALMA [C ii] Surv...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X_1538-4357/small "The ALPINE-ALMA [C ii] Survey: Size of Individual Star-forming Galaxies at z = 4-6 and Their Extended Halo Structure")
