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1.
Int J Mol Sci ; 22(6)2021 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-33802796

RESUMEN

RNA-binding proteins (RBPs) are key elements involved in post-transcriptional regulation. Ataxin-2 (ATXN2) is an evolutionarily conserved RBP protein, whose function has been studied in several model organisms, from Saccharomyces cerevisiae to the Homo sapiens. ATXN2 interacts with poly(A) binding proteins (PABP) and binds to specific sequences at the 3'UTR of target mRNAs to stabilize them. CTC-Interacting Domain3 (CID3) and CID4 are two ATXN2 orthologs present in plant genomes whose function is unknown. In the present study, phenotypical and transcriptome profiling were used to examine the role of CID3 and CID4 in Arabidopsis thaliana. We found that they act redundantly to influence pathways throughout the life cycle. cid3cid4 double mutant showed a delay in flowering time and a reduced rosette size. Transcriptome profiling revealed that key factors that promote floral transition and floral meristem identity were downregulated in cid3cid4 whereas the flowering repressor FLOWERING LOCUS C (FLC) was upregulated. Expression of key factors in the photoperiodic regulation of flowering and circadian clock pathways, were also altered in cid3cid4, as well as the expression of several transcription factors and miRNAs encoding genes involved in leaf growth dynamics. These findings reveal that ATXN2 orthologs may have a role in developmental pathways throughout the life cycle of plants.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Arabidopsis/efectos de la radiación , Ataxina-2/química , Luz , Homología de Secuencia de Aminoácido , Proteínas de Arabidopsis/genética , Regulación hacia Abajo/genética , Flores/genética , Flores/fisiología , Flores/efectos de la radiación , Regulación de la Expresión Génica de las Plantas , Redes Reguladoras de Genes , Mutación/genética , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Transcriptoma/genética
2.
Bioresour Technol ; 331: 124931, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33812139

RESUMEN

A microalgal biofilm-attached-system is an alternative cultivation method, that offers potential advantages of improved biomass productivity, efficient harvesting, and water saving. These biofilm systems have been widely tested and utilized for microalgal biomass production and wastewater treatment. This research a microalgal growth model for the biofilm attached culture system has been developed and experimentally validated, both, in single and arrayed biofilm systems. It has been shown that the model has the capability to accurately describe microalgae growth. Moreover, via the model simulation, it was observed that system structural parameters, light dilution rate, and light intensity significantly affected the culture performance. The limitations, and improvement aspects of the model, are also discussed in this study. To our knowledge, this is the first time that a mathematical model for an arrayed-biofilm-attached-system has been developed and validated. This model will certainly be helpful in the design, improvement, optimization, and evaluation of the biofilm-attached-systems.


Asunto(s)
Microalgas , Biopelículas , Biomasa , Luz
3.
Nat Commun ; 12(1): 2077, 2021 04 06.
Artículo en Inglés | MEDLINE | ID: mdl-33824321

RESUMEN

Aggregation-induced emission (AIE) has, since its discovery, become a valuable tool in the field of nanoscience. AIEgenic molecules, which display highly stable fluorescence in an assembled state, have applications in various biomedical fields-including photodynamic therapy. Engineering structure-inherent, AIEgenic nanomaterials with motile properties is, however, still an unexplored frontier in the evolution of this potent technology. Here, we present phototactic/phototherapeutic nanomotors where biodegradable block copolymers decorated with AIE motifs can transduce radiant energy into motion and enhance thermophoretic motility driven by an asymmetric Au nanoshell. The hybrid nanomotors can harness two photon near-infrared radiation, triggering autonomous propulsion and simultaneous phototherapeutic generation of reactive oxygen species. The potential of these nanomotors to be applied in photodynamic therapy is demonstrated in vitro, where near-infrared light directed motion and reactive oxygen species induction synergistically enhance efficacy with a high level of spatial control.


Asunto(s)
Luz , Nanopartículas/química , Fototerapia , Línea Celular Tumoral , Oro/química , Células HeLa , Humanos , Movimiento (Física) , Nanopartículas/ultraestructura , Polímeros/química
4.
Nat Commun ; 12(1): 2042, 2021 04 06.
Artículo en Inglés | MEDLINE | ID: mdl-33824329

RESUMEN

Daytime warm temperature elicits thermomorphogenesis in Arabidopsis by stabilizing the central thermoregulator PHYTOCHROME INTERACTING transcription FACTOR 4 (PIF4), whose degradation is otherwise promoted by the photoreceptor and thermosensor phytochrome B. PIF4 stabilization in the light requires a transcriptional activator, HEMERA (HMR), and is abrogated when HMR's transactivation activity is impaired in hmr-22. Here, we report the identification of a hmr-22 suppressor mutant, rcb-101, which surprisingly carries an A275V mutation in REGULATOR OF CHLOROPLAST BIOGENESIS (RCB). rcb-101/hmr-22 restores thermoresponsive PIF4 accumulation and reverts the defects of hmr-22 in chloroplast biogenesis and photomorphogenesis. Strikingly, similar to hmr, the null rcb-10 mutant impedes PIF4 accumulation and thereby loses the warm-temperature response. rcb-101 rescues hmr-22 in an allele-specific manner. Consistently, RCB interacts directly with HMR. Together, these results unveil RCB as a novel temperature signaling component that functions collaboratively with HMR to initiate thermomorphogenesis by selectively stabilizing PIF4 in the daytime.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Morfogénesis , Temperatura , Tiorredoxinas/metabolismo , Secuencia de Aminoácidos , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Clorofila/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efectos de la radiación , Genes Supresores , Luz , Modelos Biológicos , Morfogénesis/efectos de la radiación , Fotoperiodo , Estabilidad Proteica/efectos de la radiación , Plantones/metabolismo , Plantones/efectos de la radiación , Tiorredoxinas/química , Tiorredoxinas/genética , Factores de Transcripción/metabolismo
5.
Science ; 372(6538)2021 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-33833098

RESUMEN

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.


Asunto(s)
Carboxiliasas/química , Carboxiliasas/metabolismo , Chlorella/enzimología , Ácidos Grasos/metabolismo , Proteínas Algáceas/química , Proteínas Algáceas/metabolismo , Alcanos/metabolismo , Sustitución de Aminoácidos , Aminoácidos/metabolismo , Bicarbonatos/metabolismo , Biocatálisis , Dióxido de Carbono/metabolismo , Dominio Catalítico , Cristalografía por Rayos X , Descarboxilación , Transporte de Electrón , Flavina-Adenina Dinucleótido/química , Enlace de Hidrógeno , Luz , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Oxidación-Reducción , Fotones , Conformación Proteica , Temperatura
6.
Zoolog Sci ; 38(2): 170-178, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33812356

RESUMEN

The exumbrellar surfaces of six pelagic cnidarians from three classes were ultra-structurally compared to reveal their structural diversity in relation to their gelatinous, transparent bodies. We examined two hydrozoans (Diphyes chamissonis and Colobonema sericeum), a cubozoan (Chironex yamaguchii), and three scyphozoans (Atolla vanhöffeni, Aurelia coerulea, and Mastigias papua). The exumbrellar surfaces of the mesoglea in D. chamissonis, Ch. yamaguchii, Au. coerulea, and M. papua were covered with a simple epidermis; the shapes of the epidermal cells were remarkably different among the species. The epidermal cells of Ch. yamaguchii and M. papua possessed an array of microvilli on the apical side. The array possibly reduced light reflectance and provided some other surface properties, as seen for the cuticular nipple array in tunicates, considering the length, width, and pitch of the microvilli. The reduction of light reflectance on the array of microvilli was supported by the simulation with rigorous coupled wave analysis (RCWA). Microvilli were sparse and did not form an array in metephyrae of Au. coerulea. The mesoglea matrix beneath the basal side of the epidermis was loose in all of the species. The exumbrellar side of the mesoglea was exposed only in the mesopelagic species, At. vanhöffeni and Co. sericeum, and electron-dense layer(s) covered the surface of the mesoglea. It is uncertain whether the exumbrellar epidermis is absent in these species or the epidermal cells are completely exfoliated during the sampling and handling processes. In the latter case, the electron-dense layer(s) on the mesoglea surface might originally underlie the epidermis.


Asunto(s)
Cubomedusas/ultraestructura , Hidrozoos/ultraestructura , Escifozoos/ultraestructura , Animales , Simulación por Computador , Luz , Modelos Biológicos
7.
Nat Commun ; 12(1): 2113, 2021 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-33837202

RESUMEN

The accumulation of adenosine is strongly correlated with the need for sleep and the detection of sleep pressure is antagonised by caffeine. Caffeine also affects the circadian timing system directly and independently of sleep physiology, but how caffeine mediates these effects upon the circadian clock is unclear. Here we identify an adenosine-based regulatory mechanism that allows sleep and circadian processes to interact for the optimisation of sleep/wake timing in mice. Adenosine encodes sleep history and this signal modulates circadian entrainment by light. Pharmacological and genetic approaches demonstrate that adenosine acts upon the circadian clockwork via adenosine A1/A2A receptor signalling through the activation of the Ca2+ -ERK-AP-1 and CREB/CRTC1-CRE pathways to regulate the clock genes Per1 and Per2. We show that these signalling pathways converge upon and inhibit the same pathways activated by light. Thus, circadian entrainment by light is systematically modulated on a daily basis by sleep history. These findings contribute to our understanding of how adenosine integrates signalling from both light and sleep to regulate circadian timing in mice.


Asunto(s)
Adenosina/metabolismo , Trastornos Cronobiológicos/fisiopatología , Relojes Circadianos/efectos de los fármacos , Sueño/fisiología , Animales , Encéfalo/patología , Cafeína/farmacología , Línea Celular Tumoral , Trastornos Cronobiológicos/tratamiento farmacológico , Trastornos Cronobiológicos/etiología , Trastornos Cronobiológicos/patología , Relojes Circadianos/fisiología , Ritmo Circadiano/efectos de los fármacos , Ritmo Circadiano/fisiología , Modelos Animales de Enfermedad , Humanos , Luz , Masculino , Ratones , Ratones Transgénicos , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Fotoperiodo , Quinazolinas/administración & dosificación , Receptor de Adenosina A1/metabolismo , Receptor de Adenosina A2A/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Transducción de Señal/efectos de la radiación , Sueño/efectos de los fármacos , Privación de Sueño/complicaciones , Triazoles/administración & dosificación
8.
Nat Commun ; 12(1): 2291, 2021 04 16.
Artículo en Inglés | MEDLINE | ID: mdl-33863895

RESUMEN

Plants need to protect themselves from excess light, which causes photo-oxidative damage and lowers the efficiency of photosynthesis. Photosystem II subunit S (PsbS) is a pH sensor protein that plays a crucial role in plant photoprotection by detecting thylakoid lumen acidification in excess light conditions via two lumen-faced glutamates. However, how PsbS is activated under low-pH conditions is unknown. To reveal the molecular response of PsbS to low pH, here we perform an NMR, FTIR and 2DIR spectroscopic analysis of Physcomitrella patens PsbS and of the E176Q mutant in which an active glutamate has been replaced. The PsbS response mechanism at low pH involves the concerted action of repositioning of a short amphipathic helix containing E176 facing the lumen and folding of the luminal loop fragment adjacent to E71 to a 310-helix, providing clear evidence of a conformational pH switch. We propose that this concerted mechanism is a shared motif of proteins of the light-harvesting family that may control thylakoid inter-protein interactions driving photoregulatory responses.


Asunto(s)
Adaptación Fisiológica , Bryopsida/fisiología , Luz/efectos adversos , Complejo de Proteína del Fotosistema II/metabolismo , Estrés Fisiológico , Bryopsida/efectos de la radiación , Ácido Glutámico/genética , Concentración de Iones de Hidrógeno/efectos de la radiación , Mutagénesis Sitio-Dirigida , Resonancia Magnética Nuclear Biomolecular , Fotosíntesis/fisiología , Complejo de Proteína del Fotosistema II/genética , Complejo de Proteína del Fotosistema II/aislamiento & purificación , Complejo de Proteína del Fotosistema II/ultraestructura , Conformación Proteica en Hélice alfa , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestructura , Tilacoides/efectos de la radiación
9.
Nat Commun ; 12(1): 2333, 2021 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-33879791

RESUMEN

Acaryochloris marina is one of the cyanobacterial species that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of A. marina photosystem I (PSI) reaction center, determined by cryo-electron microscopy at 2.58 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments distinct from other type I reaction centers. The paired chlorophyll, or special pair (also referred to as P740 in this case), is a dimer of chlorophyll d and its epimer chlorophyll d'. The primary electron acceptor is pheophytin a, a metal-less chlorin. We show the architecture of this PSI reaction center is composed of 11 subunits and we identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.


Asunto(s)
Proteínas Bacterianas/química , Cianobacterias/química , Complejo de Proteína del Fotosistema I/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Clorofila/química , Clorofila/metabolismo , Microscopía por Crioelectrón , Cianobacterias/genética , Cianobacterias/metabolismo , Transporte de Electrón , Luz , Modelos Moleculares , Oxígeno/metabolismo , Fotosíntesis , Complejo de Proteína del Fotosistema I/genética , Complejo de Proteína del Fotosistema I/metabolismo , Estructura Cuaternaria de Proteína , Subunidades de Proteína , Electricidad Estática
10.
Sensors (Basel) ; 21(9)2021 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-33922365

RESUMEN

Intelligent systems for interior lighting strive to balance economical, ecological, and health-related needs. For this purpose, they rely on sensors to assess and respond to the current room conditions. With an augmented demand for more dedicated control, the number of sensors used in parallel increases considerably. In this context, the present work focuses on optical sensors with three spectral channels used to capture color-related information of the illumination conditions such as their chromaticities and correlated color temperatures. One major drawback of these devices, in particular with regard to intelligent lighting control, is that even same-type color sensors show production related differences in their color registration. Standard methods for color correction are either impractical for large-scale production or they result in large colorimetric errors. Therefore, this article shows the feasibility of a novel sensor binning approach using the sensor responses to a single white light source for cluster assignment. A cluster specific color correction is shown to significantly reduce the registered color differences for a selection of test stimuli to values in the range of 0.003-0.008 Δu'v', which enables the wide use of such sensors in practice and, at the same time, requires minimal additional effort in sensor commissioning.


Asunto(s)
Colorimetría , Iluminación , Color , Luz , Estimulación Luminosa
11.
Bioresour Technol ; 332: 125117, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33845315

RESUMEN

Here, Metal-Organic Frameworks (MOFs) coupling simultaneous saccharification and fermentation for butyric acid production using rice straw was constructed. Clostridium tyrobutyricum Δack::cat1, with deleted ack gene and overexpressed cat1 gene, was used as the butyric-acid-fermentation strain. MOFs was employed as a photocatalyst to improve butyric acid production, as well as a cytoprotective exoskeleton with immobilized cellulase for the hydrolysis of rice straw. Thus, the survival of MOFs-coated strain, the thermostability and pH stability of cellulase both remarkably increased. As a result, 55% of rice straw was hydrolyzed in 24 h, and the final concentration of butyric acid in visible light was increased by 14.23% and 29.16% compared to uncoated and coated strain without visible light, respectively. Finally, 26.25 g/L of butyric acid with a productivity of 0.41 g/L·h in fed-batch fermentation was obtained. This novel process inspires green approach of abundant low-cost feedstocks utilization for chemical production.


Asunto(s)
Clostridium tyrobutyricum , Estructuras Metalorgánicas , Oryza , Ácido Butírico , Fermentación , Luz
12.
Int J Mol Sci ; 22(6)2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33804002

RESUMEN

Antenna protein aggregation is one of the principal mechanisms considered effective in protecting phototrophs against high light damage. Commonly, it is induced, in vitro, by decreasing detergent concentration and pH of a solution of purified antennas; the resulting reduction in fluorescence emission is considered to be representative of non-photochemical quenching in vivo. However, little is known about the actual size and organization of antenna particles formed by this means, and hence the physiological relevance of this experimental approach is questionable. Here, a quasi-single molecule method, fluorescence correlation spectroscopy (FCS), was applied during in vitro quenching of LHCII trimers from higher plants for a parallel estimation of particle size, fluorescence, and antenna cluster homogeneity in a single measurement. FCS revealed that, below detergent critical micelle concentration, low pH promoted the formation of large protein oligomers of sizes up to micrometers, and therefore is apparently incompatible with thylakoid membranes. In contrast, LHCII clusters formed at high pH were smaller and homogenous, and yet still capable of efficient quenching. The results altogether set the physiological validity limits of in vitro quenching experiments. Our data also support the idea that the small, moderately quenching LHCII oligomers found at high pH could be relevant with respect to non-photochemical quenching in vivo.


Asunto(s)
Proteína con Homeodominio Antennapedia/genética , Complejos de Proteína Captadores de Luz/genética , Procesos Fototróficos/genética , Agregado de Proteínas/genética , Proteína con Homeodominio Antennapedia/química , Clorofila/química , Clorofila/genética , Clorofila/efectos de la radiación , Análisis por Conglomerados , Fluorescencia , Concentración de Iones de Hidrógeno , Luz/efectos adversos , Complejos de Proteína Captadores de Luz/química , Fotosíntesis/genética , Complejo de Proteína del Fotosistema II/genética , Complejo de Proteína del Fotosistema II/efectos de la radiación , Espectrometría de Fluorescencia , Tilacoides/química , Tilacoides/genética , Tilacoides/efectos de la radiación , Zeaxantinas/genética
13.
Nat Commun ; 12(1): 2155, 2021 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-33846325

RESUMEN

Cryptochromes (CRYs) are photoreceptors or components of the molecular clock in various evolutionary lineages, and they are commonly regulated by polyubiquitination and proteolysis. Multiple E3 ubiquitin ligases regulate CRYs in animal models, and previous genetics study also suggest existence of multiple E3 ubiquitin ligases for plant CRYs. However, only one E3 ligase, Cul4COP1/SPAs, has been reported for plant CRYs so far. Here we show that Cul3LRBs is the second E3 ligase of CRY2 in Arabidopsis. We demonstrate the blue light-specific and CRY-dependent activity of LRBs (Light-Response Bric-a-Brack/Tramtrack/Broad 1, 2 & 3) in blue-light regulation of hypocotyl elongation. LRBs physically interact with photoexcited and phosphorylated CRY2, at the CCE domain of CRY2, to facilitate polyubiquitination and degradation of CRY2 in response to blue light. We propose that Cul4COP1/SPAs and Cul3LRBs E3 ligases interact with CRY2 via different structure elements to regulate the abundance of CRY2 photoreceptor under different light conditions, facilitating optimal photoresponses of plants grown in nature.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Criptocromos/metabolismo , Fotorreceptores de Plantas/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Criptocromos/química , Criptocromos/genética , Células HEK293 , Humanos , Luz , Modelos Biológicos , Mutación/genética , Fosforilación/efectos de la radiación , Poliubiquitina/metabolismo , Unión Proteica/efectos de la radiación , Proteolisis/efectos de la radiación , Plantones/efectos de la radiación , Ubiquitinación/efectos de la radiación
14.
Int J Mol Sci ; 22(5)2021 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-33807532

RESUMEN

Organic contaminants significantly limit the bioactivity of titanium implants, resulting in the degradation known as the ageing of titanium. To reactivate the surfaces, they can be photofunctionalized, i.e., irradiated with C-range ultraviolet (UVC) light. This descriptive in vitro study compares the effectiveness of novel light-emitting diode (LED) technology to remove contaminant hydrocarbons from three different commercially available titanium dental implants: THD, TiUnite, and SLA. The surface topography and morphology were characterized by scanning electron microscopy (SEM). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS), before and after the lighting treatment, by a pair of closely placed UVC (λ = 278 nm) and LED devices for 24 h. SEM analysis showed morphological differences at the macro- and micro-scopic level. XPS analysis showed a remarkable reduction in the carbon contents after the UVC treatment: from 25.6 to 19.5 C at. % (carbon atomic concentration) in the THD; from 30.2 to 20.2 C at. % in the TiUnite; from 26.1 to 19.2 C at. % in the SLA surface. Simultaneously, the concentration of oxygen and titanium increased. Therefore, LED-based UVC irradiation decontaminated titanium surfaces and improved the chemical features of them, regardless of the kind of surface.


Asunto(s)
Tecnología Odontológica/métodos , Titanio/química , Implantes Dentales , Luz , Microscopía Electrónica de Rastreo/métodos , Espectroscopía de Fotoelectrones/métodos , Propiedades de Superficie , Rayos Ultravioleta
15.
Bioanalysis ; 13(8): 621-629, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33829873

RESUMEN

Volumetric absorptive microsampling (VAMS) is increasingly utilized for both nonclinical and clinical pharmacokinetic studies. Currently, VAMS is employed as the sampling method for the detection of antibodies for coronavirus disease 2019. Biotherapeutics whole blood stability on VAMS presents as a critical concern for the health and pharmaceutical industries. In this follow-up to our previous publication, we evaluated daclizumab and trastuzumab whole blood sample stability on VAMS. The drug recovery data we observed at room temperature for short term and -80°C for long term was very encouraging. The knowledge could help us better understand and plan important investigation timelines, especially pandemic situations where human whole blood samples from a large population are collected and in urgent need of data analysis.


Asunto(s)
Anticuerpos Monoclonales/sangre , Anticuerpos Monoclonales/farmacocinética , Pruebas con Sangre Seca/métodos , Animales , Recolección de Muestras de Sangre/métodos , Daclizumab/sangre , Daclizumab/farmacocinética , Almacenaje de Medicamentos , Luz , Ratas , Espectrometría de Masas en Tándem , Temperatura , Trastuzumab/sangre , Trastuzumab/farmacocinética
16.
Int J Mol Sci ; 22(5)2021 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-33800491

RESUMEN

Plant survival in temperate zones requires efficient cold acclimation, which is strongly affected by light and temperature signal crosstalk, which converge in modulation of hormonal responses. Cold under low light conditions affected Arabidopsis responses predominantly in apices, possibly because energy supplies were too limited for requirements of these meristematic tissues, despite a relatively high steady-state quantum yield. Comparing cold responses at optimal light intensity and low light, we found activation of similar defence mechanisms-apart from CBF1-3 and CRF3-4 pathways, also transient stimulation of cytokinin type-A response regulators, accompanied by fast transient increase of trans-zeatin in roots. Upregulated expression of components of strigolactone (and karrikin) signalling pathway indicated involvement of these phytohormones in cold responses. Impaired response of phyA, phyB, cry1 and cry2 mutants reflected participation of these photoreceptors in acquiring freezing tolerance (especially cryptochrome CRY1 at optimal light intensity and phytochrome PHYA at low light). Efficient cold acclimation at optimal light was associated with upregulation of trans-zeatin in leaves and roots, while at low light, cytokinin (except cis-zeatin) content remained diminished. Cold stresses induced elevation of jasmonic acid and salicylic acid (in roots). Low light at optimal conditions resulted in strong suppression of cytokinins, jasmonic and salicylic acid.


Asunto(s)
Aclimatación , Proteínas de Arabidopsis , Arabidopsis , Congelación , Regulación de la Expresión Génica de las Plantas , Luz , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/biosíntesis , Proteínas de Arabidopsis/genética
17.
Science ; 372(6540): 398-403, 2021 04 23.
Artículo en Inglés | MEDLINE | ID: mdl-33888639

RESUMEN

The "magic methyl" effect describes the change in potency, selectivity, and/or metabolic stability of a drug candidate associated with addition of a single methyl group. We report a synthetic method that enables direct methylation of C(sp3)-H bonds in diverse drug-like molecules and pharmaceutical building blocks. Visible light-initiated triplet energy transfer promotes homolysis of the O-O bond in di-tert-butyl or dicumyl peroxide under mild conditions. The resulting alkoxyl radicals undergo divergent reactivity, either hydrogen-atom transfer from a substrate C-H bond or generation of a methyl radical via ß-methyl scission. The relative rates of these steps may be tuned by varying the reaction conditions or peroxide substituents to optimize the yield of methylated product arising from nickel-mediated cross-coupling of substrate and methyl radicals.


Asunto(s)
Compuestos de Bencilo/química , Carbono/química , Radicales Libres/química , Hidrógeno/química , Níquel/química , Peróxidos/química , Transferencia de Energía , Enlace de Hidrógeno , Luz , Metilación , Oxígeno/química
18.
Int J Mol Sci ; 22(6)2021 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-33808792

RESUMEN

Adaptation and response to environmental changes require dynamic and fast information distribution within the plant body. If one part of a plant is exposed to stress, attacked by other organisms or exposed to any other kind of threat, the information travels to neighboring organs and even neighboring plants and activates appropriate responses. The information flow is mediated by fast-traveling small metabolites, hormones, proteins/peptides, RNAs or volatiles. Electric and hydraulic waves also participate in signal propagation. The signaling molecules move from one cell to the neighboring cell, via the plasmodesmata, through the apoplast, within the vascular tissue or-as volatiles-through the air. A threat-specific response in a systemic tissue probably requires a combination of different traveling compounds. The propagating signals must travel over long distances and multiple barriers, and the signal intensity declines with increasing distance. This requires permanent amplification processes, feedback loops and cross-talks among the different traveling molecules and probably a short-term memory, to refresh the propagation process. Recent studies show that volatiles activate defense responses in systemic tissues but also play important roles in the maintenance of the propagation of traveling signals within the plant. The distal organs can respond immediately to the systemic signals or memorize the threat information and respond faster and stronger when they are exposed again to the same or even another threat. Transmission and storage of information is accompanied by loss of specificity about the threat that activated the process. I summarize our knowledge about the proposed long-distance traveling compounds and discuss their possible connections.


Asunto(s)
Ambiente , Fenómenos Fisiológicos de las Plantas , Plantas/genética , Plantas/metabolismo , Transporte Biológico , Biomarcadores , Calcio/metabolismo , Resistencia a la Enfermedad , Fenómenos Electrofisiológicos , Interacciones Huésped-Patógeno , Luz , Especificidad de Órganos , Fotosíntesis , Fitocromo/metabolismo , Enfermedades de las Plantas , Plantas/microbiología , Plantas/efectos de la radiación , ARN de Planta , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Compuestos Orgánicos Volátiles/metabolismo
19.
BMC Plant Biol ; 21(1): 164, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33794787

RESUMEN

BACKGROUND: Diatoms contribute 20% of the global primary production and are adaptable in dynamic environments. Diatoms always bloom earlier in the annual phytoplankton succession instead of dinoflagellates. However, how diatoms acclimate to a dynamic environment, especially under changing light conditions, remains unclear. RESULTS: We compared the growth and photosynthesis under fluctuating light conditions of red tide diatom Skeletonema costatum, red tide dinoflagellate Amphidinium carterae, Prorocentrum donghaiense, Karenia mikimotoi, model diatom Phaeodactylum tricornutum, Thalassiosira pseudonana and model dinoflagellate Dinophycae Symbiodinium. Diatoms grew faster and maintained a consistently higher level of photosynthesis. Diatoms were sensitive to the specific inhibitor of Proton Gradient Regulation 5 (PGR5) depending photosynthetic electron flow, which is a crucial mechanism to protect their photosynthetic apparatus under fluctuating light. In contrast, the dinoflagellates were not sensitive to this inhibitor. Therefore, we investigate how PGR5 functions under light fluctuations in the model diatom P. tricornutum by knocking down and overexpressing PGR5. Overexpression of PGR5 reduced the photosystem I acceptor side limitation (Y (NA)) and increased growth rate under severely fluctuating light in contrast to the knockdown of PGR5. CONCLUSION: Diatoms acclimatize to fluctuating light conditions better than dinoflagellates. PGR5 in diatoms can regulate their photosynthetic electron flow and accelerate their growth under severe light fluctuation, supporting fast biomass accumulation under dynamic environments in pioneer blooms.


Asunto(s)
Diatomeas/fisiología , Dinoflagelados/fisiología , Regulación de la Expresión Génica/fisiología , Luz , Fotosíntesis , Aclimatación/genética , Diatomeas/genética , Diatomeas/crecimiento & desarrollo , Dinoflagelados/genética , Dinoflagelados/crecimiento & desarrollo
20.
Plant Physiol Biochem ; 162: 69-73, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33667968

RESUMEN

It is well known that the photosynthetic performance of a leaf is highly dependent on the systemic regulation from distal parts within a plant under light heterogeneity. However, there are few studies focusing on C4-specific processes. In the present study, two cultivars of maize (Zea mays L.), 'Rongyu 1210' (RY) and 'Zhongdan 808' (ZD), were treated with heterogeneous light (HL). The net photosynthetic rate (Pn) of newly developed leaves was found to increase in HL-treated RY, while it decreased in HL-treated ZD. Result also showed a negative correlation between the Pn and the content of malate, a key metabolite in C4 photosynthesis, in these two cultivars. In HL-treated ZD, malate content increased with a decline in the abundance of NADP-malic enzyme (EC 1.1.1.40), suggesting that less malate was decarboxylated. Moreover, a restriction of malate diffusion is proposed in HL-treated ZD, since the interface length between mesophyll cells (MC) and bundle sheath cells (BSC) decreased. In contrast, malate diffusion and subsequent decarboxylation in HL-treated RY should be stimulated, due to an increase in the abundance of NADP-malate dehydrogenase (EC 1.1.1.82) and a decline in the content of malate. In this case, malate diffusion from MC to BSC should be systemically stimulated, thereby facilitating C4 photosynthesis of a maize leaf in heterogeneous light. While if it is systemically restricted, C4 photosynthesis would be suppressed.


Asunto(s)
Malatos , Zea mays , Luz , Malato Deshidrogenasa/metabolismo , Células del Mesófilo/metabolismo , Fotosíntesis , Hojas de la Planta/metabolismo , Zea mays/metabolismo
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