-
Physiologia Plantarum 2024Maximal sunlight intensity varies diurnally due to the earth's rotation. Whether this slow diurnal pattern influences the photoprotective capacity of plants throughout...
Maximal sunlight intensity varies diurnally due to the earth's rotation. Whether this slow diurnal pattern influences the photoprotective capacity of plants throughout the day is unknown. We investigated diurnal variation in NPQ, along with NPQ capacity, induction, and relaxation kinetics after transitions to high light, in tomato plants grown under diurnal parabolic (DP) or constant (DC) light intensity regimes. DP light intensity peaked at midday (470 μmol m s while DC stayed constant at 300 μmol m s at a similar 12-hour photoperiod and daily light integral. NPQs were higher in the morning and afternoon at lower light intensities in DP compared to DC, except shortly after dawn. NPQ capacity increased from midday to the end of the day, with higher values in DP than in DC. At high light Φ did not vary throughout the day, while Φ varied consistently with NPQ capacity. Reduced Φ suggested less susceptibility to photodamage at the end of the day. NPQ induction was faster at midday than at the start of the day and in DC than in DP, with overshoot occurring in the morning and midday but not at the end of the day. NPQ relaxation was faster in DP than in DC. The xanthophyll de-epoxidation state and reduced demand for photochemistry could not explain the observed diurnal variations in photoprotective capacity. In conclusion, this study showed diurnal variation in regulated photoprotective capacity at moderate growth light intensity, which was not explained by instantaneous light intensity or increasing photoinhibition over the day and was influenced by acclimation to constant light intensity.
Topics: Solanum lycopersicum; Circadian Rhythm; Light; Photosynthesis; Photoperiod; Xanthophylls; Sunlight; Chlorophyll; Photosystem II Protein Complex; Kinetics; Plant Leaves
PubMed: 38945685
DOI: 10.1111/ppl.14410 -
Physiologia Plantarum 2024Chlorophyll (Chl) plays a crucial role in photosynthesis, functioning as a photosensitizer. As an integral component of this process, energy absorbed by this pigment is...
Chlorophyll (Chl) plays a crucial role in photosynthesis, functioning as a photosensitizer. As an integral component of this process, energy absorbed by this pigment is partly emitted as red fluorescence. This signal can be readily imaged by fluorescence microscopy and provides a visualization of photosynthetic activity. However, due to limited resolution, signals cannot be assigned to specific subcellular/organellar membrane structures. By correlating fluorescence micrographs with transmission electron microscopy, researchers can identify sub-cellular compartments and membranes, enabling the monitoring of Chl distribution within thylakoid membrane substructures in cyanobacteria, algae, and higher plant single cells. Here, we describe a simple and effective protocol for correlative light-electron microscopy (CLEM) based on the autofluorescence of Chl and demonstrate its application to selected photosynthetic model organisms. Our findings illustrate the potential of this technique to identify areas of high Chl concentration and photochemical activity, such as grana regions in vascular plants, by mapping stacked thylakoids.
Topics: Thylakoids; Chlorophyll; Photosynthesis; Microscopy, Fluorescence; Microscopy, Electron, Transmission
PubMed: 38945684
DOI: 10.1111/ppl.14417 -
Journal of Hazardous Materials Jun 2024Extracellular electron transfer was essential for degrading recalcitrant pollutants by anaerobic digestion (AD). Therefore, existing studies improved AD efficiency by...
Extracellular electron transfer was essential for degrading recalcitrant pollutants by anaerobic digestion (AD). Therefore, existing studies improved AD efficiency by enhancing the electron transfer from microbes-to-pollutants or inter-microbes. This study synthesized a novel Fe, N co-doped biochar (Fe, N-BC), which could enhance both the microbes-to-pollutants and inter-microbes electron transfer in AD. Detailed characterization data indicated that Fe, N-BC has an ordered mesoporous structure, high specific surface area (463.46 m/g), and abundant redox functional groups (Fe/Fe, pyrrolic-N), which translate into excellent biocompatibility and electrochemical properties of Fe, N-BC. By adding Fe, N-BC, the stability and efficiency of the medium-temperature AD system in the treatment of methyl orange (MO) wastewater were improved: obtained a high degradation efficiency of MO (96.8 %) and enhanced the methane (CH) production by 65 % compared to the control group. Meanwhile, Fe, N-BC reduced the accumulation of volatile fatty acids in the AD system, and the activity of anaerobic granular sludge electron transport system and coenzyme F was enhanced. In addition, Fe, N-BC showed positive enrichment of azo dyes decolorization bacteria (Georgenia) and direct interspecies electron transfer (DIET) synergistic partners (Syntrophobacter, Methanosarcina). Overall, the rapid degradation of MO and enhanced CH production in AD systems by Fe, N-BC is associated with enhancing two electronic pathways, i.e., microbes to MO and DIET between syntrophic bacteria and methanogenic archaea. This study introduced an enhanced "two-pathways of electron transfer" theory, realized by Fe, N-BC. These findings provided new insights into the interactions within AD systems and offer strategies for enhancing their performance with recalcitrant pollutants.
PubMed: 38944989
DOI: 10.1016/j.jhazmat.2024.135030 -
Organic & Biomolecular Chemistry Jun 2024A novel biomass-derived glucose-mediated one-pot multicomponent nitro-reductive cyclization method is presented for the direct synthesis of diverse pyrrole-fused...
A novel biomass-derived glucose-mediated one-pot multicomponent nitro-reductive cyclization method is presented for the direct synthesis of diverse pyrrole-fused heterocycles. The process involves two-component reactions of alkyl (NH)-pyrrole-2-carboxylates and 2-fluoronitroarenes, yielding pyrrolo[1,2-]quinoxalin-4(5)-ones, as well as three-component reactions utilizing (NH)-pyrroles, nitroarenes, and DMSO as carbon sources, resulting in various pyrrolo[1,2-]quinoxaline derivatives. High yields were achieved with broad substrate scope and gram-scale synthesis capability, including pharmaceuticals featuring pyrroloquinoxaline scaffolds. The method's key innovation lies in enabling three or four reactions in a single-pot setup, previously unexplored in pyrrole chemistry. The simplicity of nitro group reduction by biomass-derived glucose ensures practical safety during scale-up, while mechanistic insights from control experiments reveal a new paradigm in pyrrole chemistry. The tandem process demonstrates low PMI values and high step and atom economies, aligning well with green chemistry principles.
PubMed: 38940763
DOI: 10.1039/d4ob00741g -
Frontiers in Cellular and Infection... 2024and belong to the Bacteroidota phylum. Both species inhabit the oral cavity and can be associated with periodontal diseases. To survive, they must uptake heme from the...
INTRODUCTION
and belong to the Bacteroidota phylum. Both species inhabit the oral cavity and can be associated with periodontal diseases. To survive, they must uptake heme from the host as an iron and protoporphyrin IX source. Among the best-characterized heme acquisition systems identified in members of the Bacteroidota phylum is the Hmu system, with a leading role played by the hemophore-like HmuY (HmuY) protein.
METHODS
Theoretical analysis of selected HmuY proteins and spectrophotometric methods were employed to determine the heme-binding mode of the HmuY homolog (HmuY) and its ability to sequester heme. Growth phenotype and gene expression analysis of were employed to reveal the importance of the HmuY and Hmu system for this bacterium.
RESULTS
Unlike in , where HmuY uses two histidines for heme-iron coordination, other known HmuY homologs use two methionines in this process. HmuY is the first characterized representative of the HmuY family that binds heme using a histidine-methionine pair. It allows HmuY to sequester heme directly from serum albumin and HmuY, the HmuY homolog which uses two methionines for heme-iron coordination. In contrast to HmuY, which sequesters heme directly from methemoglobin, HmuY may bind heme only after the proteolytic digestion of hemoglobin.
CONCLUSIONS
We hypothesize that differences in components of the Hmu system and structure-based properties of HmuY proteins may evolved allowing different adaptations of species to the changing host environment. This may add to the superior virulence potential of over other members of the Bacteroidota phylum.
Topics: Heme; Porphyromonas gingivalis; Tannerella forsythia; Bacterial Proteins; Porphyromonas endodontalis; Humans; Gene Expression Regulation, Bacterial; Protein Binding; Iron
PubMed: 38938884
DOI: 10.3389/fcimb.2024.1421018 -
Scientific Reports Jun 2024This study investigates using magnesium foliar spray to enhance mint plants' growth and physiological performance under cadmium toxicity. It examines the effects of...
This study investigates using magnesium foliar spray to enhance mint plants' growth and physiological performance under cadmium toxicity. It examines the effects of foliar application of magnesium oxide (40 mg L), in both nano and bulk forms, on mint plants exposed to cadmium stress (60 mg kg soil). Cadmium stress reduced root growth and activity, plant biomass (32%), leaf hydration (19%), chlorophyll levels (27%), magnesium content (51%), and essential oil yield (35%), while increasing oxidative and osmotic stress in leaf tissues. Foliar application of magnesium increased root growth (32%), plant biomass, essential oil production (17%), leaf area (24%), chlorophyll content (10%), soluble sugar synthesis (33%), and antioxidant enzyme activity, and reduced lipid peroxidation and osmotic stress. Although the nano form of magnesium enhanced magnesium absorption, its impact on growth and physiological performance was not significantly different from the bulk form. Therefore, foliar application of both forms improves plants' ability to withstand cadmium toxicity. However, the study is limited by its focus on a single plant species and specific environmental conditions, which may affect the generalizability of the results. The long-term sustainability of such treatments could provide a more comprehensive understanding of magnesium's role in mitigating heavy metal stress in plants.
Topics: Magnesium Oxide; Cadmium; Mentha; Plant Leaves; Stress, Physiological; Chlorophyll; Lipid Peroxidation; Plant Roots; Oxidative Stress; Antioxidants; Magnesium; Biomass
PubMed: 38937645
DOI: 10.1038/s41598-024-65853-0 -
Nature Communications Jun 2024Global warming has a severe impact on the flowering time and yield of crops. Histone modifications have been well-documented for their roles in enabling plant plasticity...
Global warming has a severe impact on the flowering time and yield of crops. Histone modifications have been well-documented for their roles in enabling plant plasticity in ambient temperature. However, the factor modulating histone modifications and their involvement in habitat adaptation have remained elusive. In this study, through genome-wide pattern analysis and quantitative-trait-locus (QTL) mapping, we reveal that BrJMJ18 is a candidate gene for a QTL regulating thermotolerance in thermotolerant B. rapa subsp. chinensis var. parachinensis (or Caixin, abbreviated to Par). BrJMJ18 encodes an H3K36me2/3 Jumonji demethylase that remodels H3K36 methylation across the genome. We demonstrate that the BrJMJ18 allele from Par (BrJMJ18) influences flowering time and plant growth in a temperature-dependent manner via characterizing overexpression and CRISPR/Cas9 mutant plants. We further show that overexpression of BrJMJ18 can modulate the expression of BrFLC3, one of the five BrFLC orthologs. Furthermore, ChIP-seq and transcriptome data reveal that BrJMJ18 can regulate chlorophyll biosynthesis under high temperatures. We also demonstrate that three amino acid mutations may account for function differences in BrJMJ18 between subspecies. Based on these findings, we propose a working model in which an H3K36me2/3 demethylase, while not affecting agronomic traits under normal conditions, can enhance resilience under heat stress in Brassica rapa.
Topics: Brassica rapa; Flowers; Gene Expression Regulation, Plant; Histones; Quantitative Trait Loci; Jumonji Domain-Containing Histone Demethylases; Plant Proteins; Temperature; Thermotolerance; Methylation; Plants, Genetically Modified; Chlorophyll
PubMed: 38937441
DOI: 10.1038/s41467-024-49721-z -
Spectrochimica Acta. Part A, Molecular... Jun 2024The thiophene- and pyrrole-fused heterocyclic compounds have garnered significant interest for their distinctive electron-rich characteristics and notable optoelectronic...
The thiophene- and pyrrole-fused heterocyclic compounds have garnered significant interest for their distinctive electron-rich characteristics and notable optoelectronic properties. However, the construction of high-performance systems within this class is of great challenge. Herein, we develop a series of novel dithieno[3,2-b:2',3'-d] pyrrole (DTP) and tetrathieno[3,2-b:2',3'-d] pyrrole (TTP) bridged arylamine compounds (DTP-C, DTP-C, DTP-C-Fc, TTP-C-OMe, TTP-C, and TTP-C) with varying carbon chain lengths. The pertinent experimental results reveal that this series of compounds undergo completely reversible multistep redox processes. Notably, TTP-bridged compounds TTP-C and TTP-C exhibit impressive multistep near-infrared (NIR) absorption alterations with notable color changes and electroluminescent behaviors, which are mainly attributed to the charge transfer transitions from terminal arylamine units to central bridges, as supported by theoretical calculations. Additionally, compound DTP-C demonstrates the ability to visually identify gram-positive and gram-negative bacteria. Therefore, this work suggests the promising electroresponsive nature of compounds TTP-C and TTP-C, positioning them as excellent materials for various applications. It also provides a facile approach to constructing high-performance multifunctional luminescent materials, particularly those with strong and long-wavelength NIR absorption capabilities.
PubMed: 38936208
DOI: 10.1016/j.saa.2024.124704 -
Talanta Jun 2024The simultaneous synthesis of gold nanoparticles (AuNPs) and graphene by laser ablation was demonstrated. The in-situ synthesis was performed by laser ablation of a...
The simultaneous synthesis of gold nanoparticles (AuNPs) and graphene by laser ablation was demonstrated. The in-situ synthesis was performed by laser ablation of a polymer substrate covered with a gold precursor dispersion. The gold precursor was prepared in a copolymer solution of pyrrole (Py) and chitosan (Chi) to improve the nucleation of gold embedded on the laser-induced graphene electrode (LIGE). The morphology of AuNPs-pPy-Chi/LIGE was studied by scanning electron microscopy and characterized electrochemically by cyclic voltammetry. A comprehensive investigation of the electrochemical and physical features of the AuNPs-pPy-Chi/LIGE was carried out. The parameters of differential pulse voltammetry were adjusted to enhance the response to ascorbic acid (AA). The AuNPs-pPy-Chi/LIGE produced two linear ranges: from 0.25 to 5.00 and 5.00-25.00 mmol L. The limit of detection was 0.22 mmol L. Hundreds of electrodes were tested to demonstrate the excellent reproducibility of the AuNPs-pPy-Chi/LIGE fabrication. Overall, the proposed electrode allows the successful detection of AA in orange juice products with acceptable accuracy (recoveries = 97 ± 2 to 109.1 ± 0.7). The preparation strategy of the proposed AuNPs-pPy-Chi/LIGE could be adapted to detect other compounds or biomarkers.
PubMed: 38936107
DOI: 10.1016/j.talanta.2024.126446 -
JCO Precision Oncology Jun 2024The National Cancer Institute-Children's Oncology Group (NCI-COG) Pediatric MATCH trial assigns patients age 1-21 years with refractory malignancies to phase II...
Phase II Study of Ulixertinib in Children and Young Adults With Tumors Harboring Activating Mitogen-Activated Protein Kinase Pathway Alterations: APEC1621J of the National Cancer Institute-Children's Oncology Group Pediatric MATCH Trial.
PURPOSE
The National Cancer Institute-Children's Oncology Group (NCI-COG) Pediatric MATCH trial assigns patients age 1-21 years with refractory malignancies to phase II treatment arms of molecularly targeted therapies on the basis of genetic alterations detected in their tumor. Patients with activating alterations in the mitogen-activated protein kinase pathway were treated with ulixertinib, an extracellular signal-regulated kinase (ERK)1/2 inhibitor.
METHODS
As there were no previous pediatric data, ulixertinib was initially tested in a dose escalation cohort to establish the recommended phase II dose (RP2D) before proceeding to the phase II cohort. Ulixertinib was administered at 260 mg/m/dose orally twice a day (dose level 1 [DL1], n = 15) or 350 mg/m/dose orally twice a day (DL2, n = 5). The primary end point was objective response rate; secondary end points included safety/tolerability and progression-free survival (PFS).
RESULTS
Twenty patients (median 12 years; range, 5-20) were treated, all evaluable for response. CNS tumors comprised 55% (11/20) of diagnoses, with high-grade glioma and low-grade glioma most common (n = 5 each). All CNS tumors except one harbored fusions or V600E mutations. Rhabdomyosarcoma (n = 5) was the most frequent non-CNS diagnosis. DL1 was declared the RP2D in the dose escalation cohort after dose-limiting toxicities in Cycle 1 occurred in 1/6 patients at DL1 and 2/5 patients at DL2, including fatigue, anorexia, rash, nausea, vomiting, diarrhea, dehydration, hypoalbuminemia, and hypernatremia. No objective responses were observed. Six-month PFS was 37% (95% CI, 17 to 58). Three patients with -altered CNS tumors achieved stable disease >6 months.
CONCLUSION
Ulixertinib, a novel targeted agent with no previous pediatric data, was successfully evaluated in a national precision medicine basket trial. The pediatric RP2D of ulixertinib is 260 mg/m/dose orally twice a day. Limited single-agent efficacy was observed in a biomarker-selected cohort of refractory pediatric tumors.
Topics: Humans; Adolescent; Child; Female; Male; Young Adult; Child, Preschool; Neoplasms; Infant; United States; Mitogen-Activated Protein Kinases; National Cancer Institute (U.S.); MAP Kinase Signaling System; Aminopyridines; Pyrroles
PubMed: 38935895
DOI: 10.1200/PO.24.00103