Photon Reabsorption and Nonradiative Energy-Transfer-Induced Quenching of Blue Photoluminescence from Aggregated Graphene Quantum Dots

A deep understanding of the photoluminescence (PL) from aggregated graphene quantum dots (GQDs) is very important for their practical applications. Here the PL spectra from GQDs solutions at different concentrations are studied. We find that the intensity of the green emission (ca. 530–560 nm) linearly relies on the concentration of GQDs, whereas the blue PL (ca. 425 nm) intensity is below the linear relationship, indicating a concentration-induced partial quenching of blue PL. Confocal fluorescence images explicitly demonstrate the aggregation of GQDs at high concentration. The concentration-induced PL quenching is successfully interpreted by a model of photon reabsorption and nonradiative energy transfer, indicating that, at the aggregated states, the excited electrons of GQDs may nonradiatively relax to ground states through couplings with neighboring ones. Simulated fluorescence decay results show that the energy transfer between neighboring GQDs results in a prolonged dwell time of electron on high-energy state and thus increases the decay time of 425 nm emission, while 550 nm emission remains unaffected, which is consistent with the experimental results. This work will contribute to a deep understanding on PL of GQDs and is also of huge importance to extend GQDs’ applications

Cytotoxic and Antibacterial Quinone Sesquiterpenes from a <i>Myrothecium</i> Fungus

Six new quinone sesquiterpenes, myrothecols A–F (<b>1</b>–<b>6</b>), and hymenopsin B (<b>7</b>) were isolated from cultures of <i>Myrothecium</i> sp. SC0265 by bioassay-guided fractionation. Their structures were elucidated on the basis of 1D and 2D NMR and MS data. The absolute configurations of the new compounds were assigned by CD/TDDFT calculations, and that of and hymenopsin B was confirmed by X-ray diffraction analysis. Compounds <b>1</b>–<b>5</b> and hymenopsin demonstrated cytotoxic activity against human carcinoma A549, HeLa, and HepG2 cells. Compounds <b>1</b>–<b>5</b> also exhibited antibacterial activity against <i>Staphylococcus aureus</i> and <i>Bacillus cereus</i>

AC Measurements Using Organic Electrochemical Transistors for Accurate Sensing

Organic electrochemical transistors (OECTs) have been successfully employed for a variety of applications , especially chemical and biological sensing. Although the device response to analytes can be directly monitored by measuring steady-state channel currents of the devices, it is challenging to obtain stable signals with high signal-to-noise ratios. In this work, we developed a novel method for electrochemical sensing by measuring both the transconductance and the phase of the AC channel current for the first time. Then we successfully realized highly sensitive ion strength sensors and dopamine sensors based on the AC method. Our results indicate that the AC method is more sensitive than typical DC methods and can provide more stable data in sensing applications. Considering that the sensors can be conveniently integrated with AC circuits, this technology is expected to find broad applications in the future

Transcriptomic Analysis of Responses to Imbalanced Carbon: Nitrogen Availabilities in Rice Seedlings

<div><p>The internal C:N balance must be tightly controlled for the normal growth and development of plants. However, the underlying mechanisms, by which plants sense and balance the intracellular C:N status correspondingly to exogenous C:N availabilities remain elusive. In this study, we use comparative gene expression analysis to identify genes that are responsive to imbalanced C:N treatments in the aerial parts of rice seedlings. Transcripts of rice seedlings treated with four C:N availabilities (1:1, 1:60, 60:1 and 60:60) were compared and two groups of genes were classified: high C:low N responsive genes and low C:high N responsive genes. Our analysis identified several functional correlated genes including <i>chalcone synthase</i> (<i>CHS</i>), <i>chlorophyll a-b binding protein</i> (<i>CAB</i>) and other genes that are implicated in C:N balancing mechanism, such as <i>alternative oxidase 1B</i> (<i>OsAOX1B</i>), <i>malate dehydrogenase</i> (<i>OsMDH</i>) and <i>lysine and histidine specific transporter 1</i> (<i>OsLHT1</i>). Additionally, six jasmonate synthetic genes and key regulatory genes involved in abiotic and biotic stresses, such as <i>OsMYB4</i>, <i>autoinhibited calcium ATPase 3</i> (<i>OsACA3</i>) and <i>pleiotropic drug resistance 9</i> (<i>OsPDR9</i>), were differentially expressed under high C:low N treatment. Gene ontology analysis showed that high C:low N up-regulated genes were primarily enriched in fatty acid biosynthesis and defense responses. Coexpression network analysis of these genes identified eight <i>jasmonate ZIM domain protein</i> (<i>OsJAZ</i>) genes and several defense response related regulators, suggesting that high C:low N status may act as a stress condition, which induces defense responses mediated by jasmonate signaling pathway. Our transcriptome analysis shed new light on the C:N balancing mechanisms and revealed several important regulators of C:N status in rice seedlings.</p></div

Data_Sheet_2_QTL Mapping of Seed Glucosinolate Content Responsible for Environment in Brassica napus.XLSX

<p>Glucosinolates (GSLs) are a major class of secondary metabolites. The content of seed GSL is largely regulated by environments in rapeseed (Brassica napus). However, the genetic control of seed GSL content responsible for environment in B. napus has been poorly understood. In the current study, a doubled haploid (DH) population from a cross between winter and semi-winter lines of rapeseed was grown in two distinct eco-environments, Germany and China, to evaluate the eco-environment effect and dissect the quantitative trait loci (QTL) responsible for environment for seed GSL in rapeseed. The deviation value of GSL content between eco-environments (GSLE) was calculated for each line in the DH population and the QTLs for GSLE were detected. GSLE ranged from −46.90 to 36.13 μmol g⁻¹ meal in the DH population, suggesting the prominent eco-environmental effects for seed GSL in rapeseed. Four QTLs for GSLE were identified on chromosomes A04, A06, and A09 explaining 4.70∼9.93% of the phenotypic variation. Comparison of QTLs of seed GSL content between different eco-environments found three QTLs for GSL on A02 from 37.6 to 45.4 cM, A04 from 0 to 17.2 cM, and A09 from 67.0 to 98.6 cM exhibited significant difference of QTL effect between the German and Chinese eco-environments (P < 0.01), indicating the environment sensibility of these loci on seed GSL content. Moreover, flowering time (FT), an important environment adaptation trait in plant, was also investigated in this study. Comparative QTL analysis among GSLE, GSL, and FT revealed that three regions on chromosomes A02, A04, and A09 not only exhibited significant differences in QTL effect between Germany and China, but also co-located with the QTL intervals of GSLE and FT. Our results revealed that most of the GSL loci can influence GSL accumulation under different eco-environments, whereas the three QTL intervals on A02, A04, and A09 might be sensitive to the eco-environments for seed GSL content.</p

qRT-PCR analysis of CN metabolic genes at different time points after C:N treatments.

<p>Expression patterns of <i>NR</i>, <i>GOGAT</i>, <i>GS</i>, <i>PEPCase</i> and <i>PK</i> were analyzed in rice seedlings treated with four different C:N conditions (A 1:1; B 1:60; C 60:1; D 60:60) for 1, 2, 3 and 4 h. The beginning of the treatment (0 h) was used as the control and <i>Actin6</i> served as the internal reference. Values are shown as means ± SDs from three technical replicates. A representative experiment of two biological replicates is shown.</p

Validation of microarray results by qRT-PCR.

<p>(A) <i>OsLOX</i>; (B) <i>OsAOS2</i>; (C) <i>OsOPR5</i>; (D) <i>OsCHS</i>; (E) <i>OsCAB2</i>; (F) <i>OsPERO</i>. <i>Actin6</i> was used as the internal reference. The gray bars indicated the fold change of the genes between treatments (1:60, 60:1 and 60:60) and the control (1:1). Values are shown as means ± SDs from three technical replicates. A representative experiment of two biological replicates is shown.</p

Image1_Persistent Activation of Autophagy After Cisplatin Nephrotoxicity Promotes Renal Fibrosis and Chronic Kidney Disease.JPEG

Autophagy, a highly conserved catabolic pathway in eukaryotic cells, contributes to the maintenance of the homeostasis and function of the kidney. Upon acute kidney injury (AKI), autophagy is activated in renal tubular cells to act as an intrinsic protective mechanism. However, the role of autophagy in the development of chronic kidney pathologies including renal fibrosis after AKI remains unclear. In this study, we detected a persistent autophagy activation in mouse kidneys after nephrotoxicity of repeated low dose cisplatin (RLDC) treatment. 3-methyladenine (3-MA) and chloroquine (CQ), respective inhibitors of autophagy at the initiation and degradation stages, blocked autophagic flux and improved kidney repair in post-RLDC mice, as indicated by kidney weight, renal function, and less interstitial fibrosis. In vitro, RLDC induced a pro-fibrotic phenotype in renal tubular cells, including the production and secretion of pro-fibrotic cytokines. Notably, autophagy inhibitors blocked RLDC-induced secretion of pro-fibrotic cytokines in these cells. Together, the results indicate that persistent autophagy after AKI induces pro-fibrotic cytokines in renal tubular cells, promoting renal fibrosis and chronic kidney disease.</p

Coexpression network analysis of high C:low N up-regulated genes.

<p>(A) Module 1 extracted from coexpression analysis using 14 microarray identified genes. (B) Module 2 extracted from coexpression analysis using 9 microarray identified genes. Red and blue nodes indicate high C:low N up-regulated genes and the red ones are transcription factors. Other genes with known names or encode for transcription factors are marked on the nodes. Genes involved into KEGG pathways are marked with color dots beneath the nodes and the detailed information are listed on the tables.</p

Experimental design to identify genes responsive to imbalanced C:N.

<p>(A) N starved rice seedlings were treated with four different C:N conditions: balanced C:N (1:1 and 60:60) or imbalanced C:N (1:60 and 60:1). (B) Hypothetical models of genes responsive to exogenous imbalanced C:N conditions. Genes responsive to imbalanced high C:low N (60:1) or low C:high N (1:60) are proposed to show higher or lower expression levels compared with 1:1 and 60:60 treatments.</p