RESUMEN
Zebrafish maintain a remarkable ability to regenerate their neural retina following rapid and extensive loss of retinal neurons. This is mediated by Müller glial cells (MG), which re-enter the cell cycle to produce amplifying progenitor cells that eventually differentiate into the lost retinal neurons. For example, exposing adult albino zebrafish to intense light destroys large numbers of rod and cone photoreceptors, which are then restored by MG-mediated regeneration. Here, we describe an updated method for performing these acute phototoxic lesions to adult zebrafish retinas. Next, we contrast this method to a chronic, low light lesion model that results in a more muted and sustained damage to photoreceptors and does not trigger a MG-mediated regeneration response. Thus, these two methods can be used to compare and contrast the genetic and morphological changes associated with acute and chronic methods of photoreceptor degeneration.
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Modelos Animales de Enfermedad , Degeneración Retiniana , Pez Cebra , Animales , Degeneración Retiniana/patología , Degeneración Retiniana/genética , Células Ependimogliales/patología , Células Ependimogliales/metabolismo , Luz , Células Fotorreceptoras de Vertebrados/patología , Retina/patología , Retina/metabolismoRESUMEN
Inflammation within the central nervous system (CNS), which may be triggered by surgical trauma, has been implicated as a significant factor contributing to postoperative cognitive dysfunction (POCD). The relationship between mitigating inflammation at peripheral surgical sites and its potential to attenuate the CNS inflammatory response, thereby easing POCD symptoms, remains uncertain. Notably, carbon monoxide (CO), a gasotransmitter, exhibits pronounced anti-inflammatory effects. Herein, we have developed carbon monoxide-releasing micelles (CORMs), a nanoparticle that safely and locally liberates CO upon exposure to 650 nm light irradiation. In a POCD mouse model, treatment with CORMs activated by light (CORMs + hv) markedly reduced the concentrations of interleukin (IL)-6, IL-1ß, and tumor necrosis factor-alpha (TNF-α) in both the peripheral blood and the hippocampus, alongside a decrease in ionized calcium-binding adapter molecule 1 in the hippocampal CA1 region. Furthermore, CORMs + hv treatment diminished Evans blue extravasation, augmented the expression of tight junction proteins zonula occludens-1 and occludin, enhanced neurocognitive functions, and fostered fracture healing. Bioinformatics analysis and experimental validation has identified Htr1b and Trhr as potential key regulators in the neuroactive ligand-receptor interaction signaling pathway implicated in POCD. This work offers new perspectives on the mechanisms driving POCD and avenues for therapeutic intervention.
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Monóxido de Carbono , Luz , Complicaciones Cognitivas Postoperatorias , Animales , Complicaciones Cognitivas Postoperatorias/etiología , Complicaciones Cognitivas Postoperatorias/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Nanopartículas/química , Micelas , Luz RojaRESUMEN
Photodynamic therapy (PDT) is an appealing modality for cancer treatments. However, the limited tissue penetration depth of external-excitation light makes PDT impossible in treating deep-seated tumors. Meanwhile, tumor hypoxia and intracellular reductive microenvironment restrain the generation of reactive oxygen species (ROS). To overcome these limitations, a tumor-targeted self-illuminating supramolecular nanoparticle T-NPCe6-L-N is proposed by integrating photosensitizer Ce6 with luminol and nitric oxide (NO) for chemiluminescence resonance energy transfer (CRET)-activated PDT. The high H2O2 level in tumor can trigger chemiluminescence of luminol to realize CRET-activated PDT without exposure of external light. Meanwhile, the released NO significantly relieves tumor hypoxia via vascular normalization and reduces intracellular reductive GSH level, further enhancing ROS abundance. Importantly, due to the different ROS levels between cancer cells and normal cells, T-NPCe6-L-N can selectively trigger PDT in cancer cells while sparing normal cells, which ensured low side effect. The combination of CRET-based photosensitizer-activation and tumor microenvironment modulation overcomes the innate challenges of conventional PDT, demonstrating efficient inhibition of orthotopic and metastatic tumors on mice. It also provoked potent immunogenic cell death to ensure long-term suppression effects. The proof-of-concept research proved as a new strategy to solve the dilemma of PDT in treatment of deep-seated tumors.
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Nanopartículas , Fotoquimioterapia , Fármacos Fotosensibilizantes , Microambiente Tumoral , Fotoquimioterapia/métodos , Microambiente Tumoral/efectos de los fármacos , Animales , Nanopartículas/química , Fármacos Fotosensibilizantes/uso terapéutico , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacología , Humanos , Ratones , Línea Celular Tumoral , Especies Reactivas de Oxígeno/metabolismo , Transferencia de Energía , Neoplasias/tratamiento farmacológico , Neoplasias/terapia , Ratones Endogámicos BALB C , Luz , Ratones Desnudos , Óxido Nítrico/metabolismoRESUMEN
Perfluoroalkyl substances (PFASs) are typical persistent organic pollutants, and their removal is urgently required but challenging. Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of photoinduced charge carriers in photocatalysts. Herein, hexagonal ZnIn2S4 (ZIS) nanosheets were synthesized by a one-pot oil bath method and were well characterized by a series of techniques. In the degradation of sodium p-perfluorous nonenoxybenzenesulfonate (OBS), one kind of representative PFASs, the as-synthesized ZIS showed activity superior to P25 TiO2 under both simulated sunlight and visible-light irradiation. The good photocatalytic performance was attributed to the enhanced light absorption and facilitated charge separation. The pH conditions were found crucial in the photocatalytic process by influencing the OBS adsorption on the ZIS surface. Photogenerated e- and h+ were the main active species involved in OBS degradation in the ZIS system. This work confirmed the feasibility and could provide mechanistic insights into the degradation and defluorination of PFASs by visible-light photocatalysis.
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Fluorocarburos , Luz , Fotólisis , Fluorocarburos/química , Nanoestructuras/química , Catálisis , Contaminantes Químicos del Agua/química , Zinc/química , Indio/química , Modelos QuímicosRESUMEN
Photodynamic inactivation is an emerging antimicrobial treatment that can be enhanced by employing exogenous photosensitizers to eradicate foodborne pathogens. This study investigated a novel combinatory strategy to eradicate Listeria monocytogenes using blackthorn fruit peel (BFP) and blue light (BL). Extracts of BFP were characterized in terms of polyphenolic content, individual constituents, and antioxidant and antimicrobial activity. The concentration of phenolic compounds and antioxidant activity were both found to be determinants of antimicrobial activity. It was further speculated that flavonols, predominantly quercetin and rutin, were responsible for the activity of BFP against L. monocytogenes. A combination of BFP and BL resulted in a rapid inactivation of the pathogen by up to 4 log CFU/mL at 58.5 J/cm2, corresponding to 15 min BL illumination. Flow cytometry analysis revealed that the bacterial cells lost activity and suffered extensive membrane damage, exceeding 90% of the population. After photosensitizing L. monocytogenes with the BFP constituents quercetin and rutin, a 1.3-log reduction was observed. When applied together, these compounds could inflict the same damaging effect on cells as they did individually when effects were added. Therefore, the results indicate that BFP represents a natural source of (pro-)photosensitizers, which act additively to create inactivation effects. This study may help identify more effective plant-based photosensitizers to control L. monocytogenes in food-related applications.
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Frutas , Luz , Listeria monocytogenes , Fármacos Fotosensibilizantes , Extractos Vegetales , Polifenoles , Listeria monocytogenes/efectos de los fármacos , Listeria monocytogenes/efectos de la radiación , Listeria monocytogenes/crecimiento & desarrollo , Polifenoles/farmacología , Extractos Vegetales/farmacología , Extractos Vegetales/química , Frutas/química , Frutas/microbiología , Fármacos Fotosensibilizantes/farmacología , Crataegus/química , Antibacterianos/farmacología , Antioxidantes/farmacología , Quercetina/farmacología , Viabilidad Microbiana/efectos de los fármacos , Viabilidad Microbiana/efectos de la radiación , Luz AzulRESUMEN
Optogenetics, the method of light-controlled regulation of cellular processes is based on the use of the channelrhodopsins that directly generate photoinduced currents. Most of the channelrhodopsin genes have been identified in the green microalgae Chlorophyta, and the demand for increasing the number of functionally characterized channelrhodopsins and the diversity of their photochemical parameters keeps growing. We performed the expression analysis of cation channelrhodopsin (CCR) genes in natural isolates of microalgae of the genera Haematococcus and Bracteacoccus from the unique Arctic Circle region. The identified full-length CCR transcript of H. lacustris is the product of alternative splicing and encodes the Hl98CCR2 protein with no photochemical activity. The 5'-partial fragment of the B. aggregatus CCR transcript encodes the Ba34CCR protein containing a conserved TM1-TM7 membrane domain and a short cytosolic fragment. Upon heterologous expression of the TM1-TM7 fragment in CHO-K1 cell culture, light-dependent current generation was observed with the parameters corresponding to those of the CCR. The first discovered functional channelrhodopsin of Bracteacoccus has no close CCR homologues and may be of interest as a candidate for optogenetics.
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Channelrhodopsins , Chlorophyta , Chlorophyta/genética , Chlorophyta/metabolismo , Animales , Channelrhodopsins/genética , Channelrhodopsins/metabolismo , Células CHO , Cricetulus , Optogenética/métodos , LuzRESUMEN
BACKGROUND: The natural light environment is far more complex than that experienced by animals under laboratory conditions. As a burrowing species, wild mice are able to self-modulate their light exposure, a concept known as light environment sampling behaviour. By contrast, under laboratory conditions mice have little opportunity to exhibit this behaviour. To address this issue, here we introduce a simple nestbox paradigm to allow mice to self-modulate their light environment. Dark nestboxes fitted with passive infrared sensors were used to monitor locomotor activity, circadian entrainment, decision making and light environment sampling behaviour. RESULTS: Under these conditions, mice significantly reduce their light exposure to an average of just 0.8 h across a 24 h period. In addition, mice show a distinct pattern of light environment sampling behaviour, with peaks at dawn and dusk under a ramped light dark cycle. Furthermore, we show that the timing of light environment sampling behaviour depends upon endogenous circadian rhythms and is abolished in mice lacking a circadian clock, indicating a feedback loop between light, the circadian clock and behaviour. CONCLUSIONS: Our results highlight the important role of behaviour in modifying the light signals available for circadian entrainment under natural conditions.
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Ritmo Circadiano , Luz , Animales , Ritmo Circadiano/fisiología , Ratones/fisiología , Conducta Animal/fisiología , Ratones Endogámicos C57BL , Masculino , Actividad Motora/fisiología , Fotoperiodo , Relojes Circadianos/fisiologíaRESUMEN
Artificial light at night (ALAN) is an increasingly pervasive pollutant that alters animal behaviour and physiology, with cascading impacts on development and survival. Recent evidence links exposure to ALAN with neural damage, potentially due to its action on melatonin synthesis, a powerful antioxidant. However, these data are scarce and taxonomically limited. Here, we used micro-CT to test the effects of short-term ALAN exposure on brain volumes in the Australian garden orb-weaving spider (Hortophora biapicata), a species commonly found in urban areas and, specifically, around street lights. We found that short-term ALAN exposure was linked to reductions in the volumes of brain structures in the primary eye visual pathway, potentially as a consequence of oxidative stress or plastic shifts in neural investment. Although the effects of ALAN were subtle, they provided new insights into potential mechanisms underpinning the behavioural and physiological impacts of ALAN in this important urban predator.
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Encéfalo , Luz , Arañas , Animales , Arañas/fisiología , Arañas/efectos de la radiación , Encéfalo/efectos de la radiación , Encéfalo/fisiología , Iluminación/efectos adversos , Femenino , Microtomografía por Rayos XRESUMEN
Rapid and accurate bacterial identification is essential for timely treatment of infections like sepsis. While traditional methods are reliable, they lack speed, and advanced molecular techniques often suffer from cost and complexity. The bacterial detection technology based on optical scattering system offers a rapid, label-free alternative but traditionally relies on complex lasers and analysis. Our enhanced approach utilizes RGB light emitting diodes (LEDs) as the light source. Three diffraction images of bacterial colonies from different LED colors are separately captured by a USB camera and combined using an image registration algorithm to enhance image sharpness. Our approach utilizes an object detection model, i.e., YOLOv8, for analysis achieving high-accuracy differentiation between bacterial strains. We demonstrate the effectiveness of this approach, achieving an average accuracy of 97% (mAP50 of 0.97), including accurate discrimination of closely related strains and the significant pathogen Staphylococcus aureus MRSA 1320. Our enhancement offers advantages in affordability, usability, and seamless integration into existing workflows, providing an alternative for rapid bacterial identification.
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Algoritmos , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Luz , Bacterias/clasificación , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
Photosynthesis is one of the most important biological processes on Earth, providing the main source of bioavailable energy, carbon, and oxygen via the use of sunlight. Despite this importance, the minimum light level sustaining photosynthesis and net growth of primary producers in the global ocean is still unknown. Here, we present measurements from the MOSAiC field campaign in the central Arctic Ocean that reveal the resumption of photosynthetic growth and algal biomass buildup under the ice pack at a daily average irradiance of not more than 0.04 ± 0.02 µmol photons m-2 s-1 in late March. This is at least one order of magnitude lower than previous estimates (0.3-5 µmol photons m-2 s-1) and near the theoretical minimum light requirement of photosynthesis (0.01 µmol photons m-2 s-1). Our findings are based on measurements of the temporal development of the under-ice light field and concurrent measurements of both chlorophyll a concentrations and potential net primary production underneath the sea ice at 86 °N. Such low light requirements suggest that euphotic zones where photosynthesis can occur in the world's oceans may extend further in depth and time, with major implications for global productivity estimates.
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Biomasa , Microalgas , Fotosíntesis , Luz Solar , Fotosíntesis/fisiología , Fotosíntesis/efectos de la radiación , Regiones Árticas , Microalgas/metabolismo , Microalgas/crecimiento & desarrollo , Cubierta de Hielo , Clorofila A/metabolismo , Clorofila/metabolismo , Luz , Océanos y MaresRESUMEN
Biofilms are considered a basal resource with high nutritional quality in stream food webs, as periphytic algae are abundant of polyunsaturated fatty acids (PUFAs). PUFAs are essential for growth and reproduction of consumers who cannot or have very limited capacity to biosynthesize. Yet, how the nutritional quality based on PUFA of basal food sources changes with light intensity remains unclear. We conducted a manipulative experiment in mesocosms to explore the response and mechanisms of nutritional quality to shading, simulating riparian restoration. We found a significant increase in PUFA% (including arachidonic acid, ARA) under shading conditions. The increased PUFA is caused by the algal community succession from Cyanobacteria and Chlorophyta to Bacillariophyta which is abundant of PUFA (especially eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA). On the other hand, shading increased PUFA via upregulating enzymes such as Δ12 desaturase (FAD2, EC:1.14.19.6) and 3-ketoacyl-CoA synthase (KCS, EC:2.3.1.199) in the biosynthesis of unsaturated fatty acid elongation pathways. Our findings imply that riparian reforestation by decreasing light intensity increases the nutritional quality of basal resources in streams, which may enhance transfer of good quality carbon to consumers in higher trophic levels through bottom-up effects.
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Ácidos Grasos Insaturados , Cadena Alimentaria , Luz , Ríos , Ríos/microbiología , Ríos/química , Ácidos Grasos Insaturados/análisis , Ácidos Grasos Insaturados/metabolismo , Cianobacterias/metabolismo , Cianobacterias/crecimiento & desarrollo , Chlorophyta/metabolismo , Chlorophyta/crecimiento & desarrollo , Diatomeas/metabolismo , Diatomeas/crecimiento & desarrollo , Valor NutritivoRESUMEN
The construction of heterojunction is an effective and conventional method to improve the photocatalytic activity of photocatalysts. On this basis, how to further regulate the separation and migration of photogenerated carrier is worthy of further investigation. As a mature and efficient modification method, oxygen defect engineering was used to regulate the S-scheme heterojunction composed of AgIO3 and Bi4Ti3O12 to further enhance the photocatalytic activity of the constructed heterojunction in this study. In addition to improving the visible light absorption of the photocatalyst and providing active sites, the introduction of oxygen vacancies can also strengthen the internal electric field between the two semiconductors by expanding the Fermi level gap, which can be verified by Mott-Schottky experiment and DFT calculations, resulting in more efficient photogenerated carrier separation efficiency. As a result, compared with AgIO3/Bi4Ti3O12, the AgIO3/Bi4Ti3O12 heterojunction modulated by oxygen defect engineering exhibited excellent photocatalytic activity, which proves the feasibility of the regulation of the interfacial electric field. This work provides a new idea for the modulation strategy of the interface electric field.
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Oxígeno , Catálisis , Oxígeno/química , Titanio/química , Bismuto/química , LuzRESUMEN
Achieving negative surgical margins, defined as no tumor found on the edges of the resected tissue, during lumpectomy for breast cancer is critical for mitigating the risk of local recurrence. To identify nonpalpable tumors that cannot be felt, pre-operative placements of wire and wire-free localization devices are typically employed. Wire-free localization approaches have significant practical advantages over wired techniques. In this study, we introduce an innovative localization system comprising a light-emitting diode (LED)-based implantable device and handheld system. The device, which is needle injectable and wire free, utilizes multiple wirelessly powered LEDs to provide direct visual guidance for lumpectomy. Two distinct colors, red and blue, provide a clear indication of tissue depth: blue light is absorbed strongly in tissue, visible within a close range of <1 cm, while red light remains visible through several centimeters of tissue. The LEDs, integrated with an impedance-matching circuit and receiver coil, are encapsulated in biocompatible epoxy for injection with a 12 G needle. Our findings demonstrate that the implant exhibits clearly perceivable depth-dependent color changes and remains visible through >2 cm of ex vivo chicken breast and bovine muscle tissue using less than 4 W of transmitted power from a handheld antenna. These miniaturized needle-injectable localization devices show promise for improving surgical guidance of nonpalpable breast tumors.
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Neoplasias de la Mama , Luz , Mastectomía Segmentaria , Tecnología Inalámbrica , Femenino , Mastectomía Segmentaria/instrumentación , Animales , Neoplasias de la Mama/cirugía , Tecnología Inalámbrica/instrumentación , Humanos , Prótesis e Implantes , Bovinos , PollosRESUMEN
BACKGROUND: Volvocales in green algae have evolved by multicellularity of Chlamydomonas-like unicellular ancestor. Those with various cell numbers exist, such as unicellular Chlamydomonas, four-celled Tetrabaena, and Volvox species with different cell numbers (~1,000, ~5,000, and ~10,000). Each cell of these organisms shares two cilia and an eyespot, which are used for swimming and photosensing. They are all freshwater microalgae but inhabit different fluid environments: unicellular species live in low Reynolds-number (Re) environments where viscous forces dominate, whereas multicellular species live in relatively higher Re where inertial forces become non-negligible. Despite significant changes in the physical environment, during the evolution of multicellularity, they maintained photobehaviors (i.e., photoshock and phototactic responses), which allows them to survive under changing light conditions. RESULTS: In this study, we utilized high-speed imaging to observe flash-induced changes in the ciliary beating manner of 27 Volvocales strains. We classified flash-induced ciliary responses in Volvocales into four patterns: "1: temporal waveform conversion", "2: no obvious response", "3: pause in ciliary beating", and "4: temporal changes in ciliary beating directions". We found that which species exhibit which pattern depends on Re, which is associated with the individual size of each species rather than phylogenetic relationships. CONCLUSIONS: These results suggest that only organisms that acquired different patterns of ciliary responses survived the evolutionary transition to multicellularity with a greater number of cells while maintaining photobehaviors. This study highlights the significance of the Re as a selection pressure in evolution and offers insights for designing propulsion systems in biomimetic micromachines.
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Evolución Biológica , Cilios , Cilios/fisiología , Chlorophyta/fisiología , Chlorophyta/genética , Volvox/genética , Volvox/fisiología , LuzRESUMEN
The lightness of a surface depends not only on the amount of light reflected off, it but also on the context in which it is embedded. Despite a long history of research, neural correlates of context-dependent lightness perception remain a topic of ongoing debate. Here, we seek to expand on the existing literature by measuring functional magnetic resonance imaging (fMRI) responses to lightness variations induced by the context. During the fMRI experiment, we presented 10 participants with a dynamic stimulus in which either the luminance of a disk or its surround is modulated at four different frequencies ranging from 1 to 8 Hz. Behaviorally, when the surround luminance is modulated at low frequencies, participants perceive an illusory change in the lightness of the disk (lightness induction). In contrast, they perceive little or no induction at higher frequencies. Using this frequency dependence and controlling for long-range responses to border contrast and luminance changes, we found that activity in the primary visual cortex (V1) correlates with lightness induction, providing further evidence for the involvement of V1 in the processing of context-dependent lightness.
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Sensibilidad de Contraste , Imagen por Resonancia Magnética , Estimulación Luminosa , Humanos , Imagen por Resonancia Magnética/métodos , Adulto , Masculino , Estimulación Luminosa/métodos , Femenino , Sensibilidad de Contraste/fisiología , Adulto Joven , Corteza Visual Primaria/fisiología , Corteza Visual/fisiología , LuzRESUMEN
Objective: To investigate the anatomical structure changes of the anterior segment and dynamic pupil changes in eyes with suspected primary angle-closure (PACS) under light and dark conditions, and their correlation with the occurrence of acute primary angle-closure (APAC). Methods: This cross-sectional study collected data from 37 PACS patients (66 eyes) who visited the ophthalmology clinic of the Second Affiliated Hospital of Harbin Medical University between September 2019 and March 2021. The patients included 12 males and 25 females, with an average age of (61.27±7.35) years. Of the 66 eyes, 58 had no history of APAC in the contralateral eye, while 8 had a history of APAC in the contralateral eye. Patients without a history of APAC in both eyes underwent the dark room prone provocative test (DRPPT), and the eyes were divided into three groups: DRPPT- (44 eyes), DRPPT+ (14 eyes), and APAC (8 eyes). The DRPPT+ and APAC groups were combined into the APAC+ group. All patients underwent ultrasound biomicroscopy (UBM) to measure the changes in various parameters under light and dark conditions, including anterior chamber angle 500 (ACA500Δ) and 1000 (ACA1000Δ), angle opening distance 500 (AOD500Δ) and 1000 (AOD1000Δ), and iris thickness 500 (IT500Δ) and 1000 (IT1000Δ). Anterior segment analysis was performed to capture the pupil changes under light and dark conditions, recording pupil diameter, maximum dilation speed (Vmax), maximum constriction speed (Vmin), and average speed (Vm). Results: There was no significant difference in the parameters between DRPPT+ group and APAC group (P>0.05). In the difference analysis, it was found that the Vm value of DRPPT- group [(0.17±0.07) mm/s] was higher than that of APAC+ group [(0.13±0.06)mm/s], and the difference was statistically significant (P<0.05). There was no significant difference in other parameters (P>0.05). Vmax was positively correlated with temporal ACA1000Δ and temporal AOD1000Δ in all patients with PACS (r=0.302, 0.260; P<0.05), Vmin was negatively correlated with temporal ACA1000Δ and temporal AOD1000Δ (r=-0.338, -0.330; P<0.05). Conclusions: The dynamic changes in the anterior segment and pupil under different lighting conditions provide insights into the risk factors and potential predictive indicators for the occurrence of APAC in PACS patients.
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Segmento Anterior del Ojo , Glaucoma de Ángulo Cerrado , Pupila , Humanos , Masculino , Glaucoma de Ángulo Cerrado/fisiopatología , Femenino , Estudios Transversales , Persona de Mediana Edad , Segmento Anterior del Ojo/diagnóstico por imagen , Luz , Microscopía Acústica , Presión IntraocularRESUMEN
Shade avoidance helps plants maximize their access to light for growth under crowding. It is unknown, however, whether a priming shade avoidance mechanism exists that allows plants to respond more effectively to successive shade conditions. Here, we show that the shade-intolerant plant Arabidopsis can remember a first experienced shade event and respond more efficiently to the next event on hypocotyl elongation. The transcriptional regulator PHYTOCHROME-INTERACTING FACTOR 7 (PIF7) and the histone H3K27-demethylase RELATIVE OF EARLY FLOWERING 6 (REF6) are identified as being required for this shade avoidance memory. RNA-sequencing analysis reveals that shade induction of shade-memory-related genes is impaired in the pif7 and ref6 mutants. Based on the analyses of enrichments of H3K27me3, REF6 and PIF7, we find that priming shade treatment induces PIF7 accumulation, which further recruits REF6 to demethylate H3K27me3 on the chromatin of certain shade-memory-related genes, leading to a state poised for their transcription. Upon a second shade treatment, enhanced shade-mediated inductions of these genes result in stronger hypocotyl growth responses. We conclude that the transcriptional memory mediated by epigenetic modification plays a key role in the ability of primed plants to remember previously experienced shade and acquire enhanced responses to recurring shade conditions.
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Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Histonas , Hipocótilo , Arabidopsis/genética , Arabidopsis/fisiología , Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Hipocótilo/crecimiento & desarrollo , Hipocótilo/genética , Hipocótilo/metabolismo , Histonas/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Luz , Cromatina/metabolismo , Mutación , Epigénesis Genética , Proteínas de Unión al ADN , Factores de TranscripciónRESUMEN
A Fe2+-EGTA(ethylene glycol-bis (ß-aminoethyl ether)-N,N,N',N'-tetraacetic acid)-H2O2 system emits photons, and quenching this chemiluminescence can be used for determination of anti-hydroxyl radical (â¢OH) activity of various compounds. The generation of â¢OH and light emission due to oxidative damage to EGTA may depend on the buffer and pH of the reaction milieu. In this study, we evaluated the effect of pH from 6.0 to 7.4 (that may occur in human cells) stabilized with 10 mM phosphate buffer (main intracellular buffer) on a chemiluminescence signal and the ratio of this signal to noise (light emission from medium alone). The highest signal (4698 ± 583 RLU) and signal-to-noise ratio (9.7 ± 1.5) were noted for pH 6.6. Lower and higher pH caused suppression of these variables to 2696 ± 292 RLU, 4.0 ± 0.8 at pH 6.2 and to 3946 ± 558 RLU, 5.0 ± 1.5 at pH 7.4, respectively. The following processes may explain these observations: enhancement and inhibition of â¢OH production in lower and higher pH; formation of insoluble Fe(OH)3 at neutral and alkaline environments; augmentation of â¢OH production by phosphates at weakly acidic and neutral environments; and decreased regeneration of Fe2+-EGTA in an acidic environment. Fe2+-EGTA-H2O2 system in 10 mM phosphate buffer pH 6.6 seems optimal for the determination of anti-â¢OH activity.
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Ácido Egtácico , Peróxido de Hidrógeno , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Humanos , Ácido Egtácico/química , Ácido Egtácico/análogos & derivados , Radical Hidroxilo/química , Hierro/química , Luminiscencia , Mediciones Luminiscentes/métodos , LuzRESUMEN
The widespread environmental contamination resulting from the misuse of tetracycline antibiotics (TCs) has garnered significant attention and study by scholars. Photocatalytic technology is one of the environmentally friendly advanced oxidation processes (AOPs) that can effectively solve the problem of residue of TCs in the water environment. This study involved the synthesis of the heterogeneous magnetic photocatalytic material of CoFe2O4/NaBiO3 via the solvothermal method, and it was characterized using different characterization techniques. Then, the photocatalytic system under visible light (Vis) was coupled with peroxymonosulfate (PMS) to explore the performance and mechanism of degradation of tetracycline hydrochloride (TCH) in the wastewater. The characterization results revealed that CoFe2O4/NaBiO3 effectively alleviated the agglomeration phenomenon of CoFe2O4 particles, increased the specific surface area, effectively narrowed the band gap, expanded the visible light absorption spectrum, and inhibited recombination of photogenerated electron-hole pairs. In the Vis+CoFe2O4/NaBiO3+PMS system, CoFe2O4/NaBiO3 effectively activated PMS to produce hydroxyl radicals (·OH) and sulfate radicals (SO4-). Under the conditions of a TCH concentration of 10 mg/L-1, a catalyst concentration of 1 g/L-1 and a PMS concentration of 100 mg/L-1, the degradation efficiency of TCH reached 94% after 100 min illumination. The degradation of TCH was enhanced with the increase in the CoFe2O4/NaBiO3 and PMS dosage. The solution pH and organic matter had a significant impact on TCH degradation. Notably, the TCH degradation efficiency decreased inversely with increasing values of these parameters. The quenching experiments indicated that the free radicals contributing to the Vis+CoFe2O4/NaBiO3+PMS system were ·OH followed by SO4-, hole (h+), and the superoxide radical (O2-). The main mechanism of PMS was based on the cycle of Co3+ and Co2+, as well as Fe3+ and Fe2+. The cyclic tests and characterization by XRD and FT-IR revealed that CoFe2O4/NaBiO3 had good degradation stability. The experimental findings can serve as a reference for the complete removal of antibiotics from wastewater.
Asunto(s)
Cobalto , Compuestos Férricos , Sulfatos , Tetraciclina , Contaminantes Químicos del Agua , Tetraciclina/química , Cobalto/química , Catálisis , Sulfatos/química , Compuestos Férricos/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Aguas Residuales/química , Luz , Oxidación-Reducción , Antibacterianos/química , Fotólisis , Peróxidos , Compuestos de SodioRESUMEN
In plants, development of all above-ground tissues relies on the shoot apical meristem (SAM) which balances cell proliferation and differentiation to allow life-long growth. To maximize fitness and survival, meristem activity is adjusted to the prevailing conditions through a poorly understood integration of developmental signals with environmental and nutritional information. Here, we show that sugar signals influence SAM function by altering the protein levels of SHOOT MERISTEMLESS (STM), a key regulator of meristem maintenance. STM is less abundant in inflorescence meristems with lower sugar content, resulting from plants being grown or treated under limiting light conditions. Additionally, sucrose but not light is sufficient to sustain STM accumulation in excised inflorescences. Plants overexpressing the α1-subunit of SUCROSE-NON-FERMENTING1-RELATED KINASE 1 (SnRK1) accumulate less STM protein under optimal light conditions, despite higher sugar accumulation in the meristem. Furthermore, SnRK1α1 interacts physically with STM and inhibits its activity in reporter assays, suggesting that SnRK1 represses STM protein function. Contrasting the absence of growth defects in SnRK1α1 overexpressors, silencing SnRK1α in the SAM leads to meristem dysfunction and severe developmental phenotypes. This is accompanied by reduced STM transcript levels, suggesting indirect effects on STM. Altogether, we demonstrate that sugars promote STM accumulation and that the SnRK1 sugar sensor plays a dual role in the SAM, limiting STM function under unfavorable conditions but being required for overall meristem organization and integrity under favorable conditions. This highlights the importance of sugars and SnRK1 signaling for the proper coordination of meristem activities.