•Quick response time less than one minute.•High sensitivity and anti-interference towards Fe3+.•Low detection limit as low as 0.28 μM.•Successful imaging application in HeLa cells.Fe3+ plays a crucial role in many vital cell functions and its detection has attracted considerable attention. In this work, a water-soluble rhodamine-based chemosensor RL has been designed and synthesized as an “off-on” chemosensor for Fe3+ detection. Upon the addition of Fe3+, RL displayed obvious color change, quick fluorescence enhancement, high sensitivity and anti-interference capacity over other metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Al3+, Sn2+, Pb2+, Bi3+, Cr3+, Mn2+, Co2+, Ni2+, Pd2+, Cu2+, Ag+, Zn2+, Cd2+, Hg2+). The detection limit for Fe3+ was calculated to be 0.28 μM with the binding constant Ka to be 4.67 × 108 M−2. Furthermore, an application of RL in the imaging of HeLa cells exposed to Fe3+ was also successfully demonstrated.A water-soluble rhodamine-based chemosensor RL with high sensitivity, selectivity and anti-interference capacity and low detection limit for Fe3+ was fabricated and successfully used for living cell imaging.Download high-res image (158KB)Download full-size image

•A novel capillary zone electrophoresis method was established to analyze adenine nucleotides from Saccharomyces cerevisiae extract.•Validation analyses suggest that the method is reliable and accurate with high recovery and precision in the range of linearity.•It is the first time that ATP, ADP, AMP, and cAMP were detected simultaneously in yeast.•The current method may contribute to further metabolomics and system biology investigations of yeast.Adenosine triphosphate and its metabolites are involved in the cellular metabolism process in Saccharomyces cerevisiae. It is very important to simultaneously determine the relative contents of ATP and its metabolites in yeast. In this study, an effective capillary zone electrophoresis method with high selectivity was established. The calibration curves were linear in the concentration range from 1 to 20 mg/L (ATP and cAMP) and 2 to 40 mg/L (ADP and AMP) with excellent correlation coefficients (r2) > 0.999. The recovery of ATP, ADP, AMP, and cAMP were 99.4%, 94.7%, 100.3% and 99.6%, respectively. Simple sample preparation and easy detection of ATP and its metabolites make this method suitable for the study of changes in the four adenine nucleotides levels caused by caloric restriction in yeast. It is expected that the current method may contribute to further energy metabolism and related investigations of yeast.

Trivalent chromium [Cr(III)] has been shown as an essential trace element for human health. Previous studies depict that Cr(III) plays important roles in maintaining normal glucose and lipid metabolism, whereas its effect on the hepatic lipid metabolism is still unknown. In the present study, we investigated the effects and underlying mechanisms of Cr on hepatic steatosis induced by oleic acid (OA) in human hepatoma SMMC-7721 cells. Hepatic steatosis model was co-administered with Cr. Indexes of lipid accumulation were determined and associated genes expression were analyzed. The data showed that OA could induce lipid accumulation and triglyceride (TG) content in SMMC-7721 cells, and significantly increase the expression of cluster of differentiation 36 (CD36) and diacylglycerol acyltransferase 2 (DGAT2). This steatosis effect of OA was ameliorated by Cr. The TG accumulation and up-regulation of CD36 and DGAT2 genes followed steatosis induction were inhibited by Cr. After the treatment of Cr, excessive intracellular OA content was also attenuated. Furthermore, Cr still performed inhibitory effect of DGAT2 expression at the presence of DGAT2 agonist or inhibitor, which indicated that the inhibitory effect of Cr on lipogenesis is associated with the downregulation of DGAT2 expression. These findings demonstrate that Cr alleviates hepatic steatosis via suppressing CD36 expression to prevent fatty acid uptake, as well as suppressing DGAT2 expression to inhibit TG synthesis. It suggests that CD36 and DGAT2 might become the novel drug targets for their properties in hepatic steatosis. Most importantly, Cr may be a potential anti-steatosis candidate to offer protective effects against liver damage.

H2S produced in small amounts by mammalian cells has been identified in mediating biological signaling functions. However, the in situ trapping of endogenous H2S generation is still handicapped by a lack of straightforward methods with high selectivity and fast response. Here, we encapsulate a semi-cyanine-BODIPY hybrid dye (BODInD-Cl) and its complementary energy donor (BODIPY1) into the hydrophobic interior of an amphiphilic copolymer (mPEG-DSPE), especially for building up a ratiometric fluorescent H2S nanoprobe with extraordinarily fast response. A remarkable red-shift in the absorption band with a gap of 200 nm in the H2S response can efficiently switch off the Förster resonance energy transfer (FRET) from BODIPY1 to BODInD-Cl, subsequently recovering the donor fluorescence. Impressively, both the interior hydrophobicity of supramolecular micelles and electron-withdrawing nature of indolium unit in BODInD-Cl can sharply increase aromatic nucleophilic substitution with H2S. The ratiometric strategy based on the unique self-assembled micellar aggregate NanoBODIPY achieves an extremely fast response, enabling in situ imaging of endogenous H2S production and mapping its physiological and pathological consequences. Moreover, the amphiphilic copolymer renders the micellar assembly biocompatible and soluble in aqueous solution. The established FRET-switchable macromolecular envelope around BODInD-Cl and BODIPY1 enables cellular uptake, and makes a breakthrough in the trapping of endogenous H2S generation within raw264.7 macrophages upon stimulation with fluvastatin. This study manifests that cystathione γ-lyase (CSE) upregulation contributes to endogenous H2S generation in fluvastatin-stimulated macrophages, along with a correlation between CSE/H2S and activating Akt signaling pathway.

Paclitaxel (PTX) is an extensively used potent chemotherapy drug; however, low water solubility, poor bioavailability, and emergence of drug resistance in patients limited its biological application. In this report, we proposed a new drug delivery system for cancer therapy based on graphene oxide (GO), a novel 2D nanomaterial obtained from the oxidation of natural graphite, to improve the utilization rate of PTX. PTX was first connected to biocompatible 6-armed poly(ethylene glycol), followed by covalent introduction into the surface of GO sheets via a facile amidation process under mild conditions, affording the drug delivery system, GO-PEG-PTX (size 50–200 nm). GO-PEG nanosized carrier could quickly enter into human lung cancer A549 and human breast cancer MCF-7 cells verified by inverted fluorescence microscope using fluorescein isothiocyanate as probe. This nanocarrier was nontoxic to A549 and MCF-7 cells without linking with PTX. Nevertheless, GO-PEG-PTX showed remarkably high cytotoxicity to A549 and MCF-7 cells in a broad range of concentration of PTX and time compared to free PTX. This kind of nanoscale drug delivery system based on PEGylated GO may find widespread application in biomedicine.Keywords: drug delivery; graphene oxide; paclitaxel; PEG

Classic fluorescent dyes, such as coumarin, naphthalimide, fluorescein, BODIPY, rhodamine, and cyanines, are cornerstones of various spectroscopic and microscopic methods, which hold a prominent position in biological studies. We recently found that 9-amino-benzo[c]cinnoliniums make up a novel group of fluorophores that can be used in biological studies. They are featured with a succinct conjugative push–pull backbone, a broad absorption band, and a large Stokes shift. They are potentially useful as a small-molecule alternative to R-phycoerythrin to pair with fluorescein in multiplexing applications.

Graphene oxide (GO), a novel 2D nanomaterial prepared by the oxidation of natural graphite, has been paid much attention in the area of drug delivery due to good biocompatibility and low toxicity. In the present work, 6-armed poly(ethylene glycol) was covalently introduced into the surface of GO sheets via a facile amidation process under mild conditions, making the modified GO, GO-PEG (PEG: 65 wt %, size: 50–200 nm), stable and biocompatible in physiological solution. This nanosized GO-PEG was found to be nontoxic to human lung cancer A549 and human breast cancer MCF-7 cells via cell viability assay. Furthermore, paclitaxel (PTX), a widely used cancer chemotherapy drug, was conjugated onto GO-PEG via π–π stacking and hydrophobic interactions to afford a nanocomplex of GO-PEG/PTX with a relatively high loading capacity for PTX (11.2 wt %). This complex could quickly enter into A549 and MCF-7 cells evidenced by inverted fluorescence microscopy using Fluorescein isothiocyanate as a probe, and it also showed remarkably high cytotoxicity to A549 and MCF-7 cells in a broad range of concentration of PTX and time compared to free PTX. This kind of nanoscale drug delivery system on the basis of PEGylated GO may find potential application in biomedicine.Keywords: A549; graphene oxide; MCF-7; paclitaxel; PEG

Chromium is a significant mutagen and carcinogen in environment. We compared the effects of tri- and hexavalent chromium on cytotoxicity and oxidative stress in yeast. Cell growth was inhibited by Cr3+ or Cr6+, and Cr6+ significantly increased the lethal rate compared with Cr3+. Both Cr3+ and Cr6+ can enter into the yeast cells. The percent of propidium iodide permeable cells treated with Cr3+ is almost five times as that treated with the same concentration of Cr6+. Levels of TBARS, O2−, and carbonyl protein were significantly increased in both Cr6+- and Cr3+-treated cells in a concentration- and time-dependent manner. Moreover, the accumulation of these stress markers in Cr6+-treated cells was over the Cr3+-treated ones. The decreased GSH level and increased activity of GPx were observed after 300 μM Cr6+-exposure compared with the untreated control, whereas there was no other change of GSH content in cells treated with Cr3+ even at very high concentration. Exposure to both Cr3+ and Cr6+ resulted in the decrease of activities of SOD and catalase. Furthermore, the effect of Cr6+ is stronger than that of Cr3+. Null mutation sensitivity assay demonstrated that the gsh1 mutant was sensitive to Cr6+ other than Cr3+, the apn1 mutant is more sensitive to Cr6+ than Cr3+, and the rad1 mutant is sensitive to both Cr6+ and Cr3+. Therefore, Cr3+ can be concluded to inhibit cell growth probably due to the damage of plasma membrane integrality in yeast. Although both tri- and hexavalent chromium can induce cytotoxicity and oxidative stress, the action mode of Cr3+ is different from that of Cr6+, and serious membrane damage caused by Cr3+ is not the direct consequence of the increase of lipid peroxidation.

Azadirachtin has remarkable toxic and growth inhibitory effects on Ostrinia furnacalis (Guenée) (Lepidoptera: Pyralidae). In this study, sublethal effects of azadirachtin on fatty acid metabolism and sex pheromone biosynthesis in O. furnacalis were investigated. Quantities of fatty acids were significantly reduced when larvae were fed a diet containing azadirachtin at 0.1–10 ppm. After 10 days, fatty acids were reduced by 50% on a diet treated with 10 ppm azadirachtin; the relative composition of fatty acids was also affected. The relative proportion of C18:2 fatty acid decreased significantly in adult survivors, correlating with decreased fecundity. Furthermore, sex pheromone titers in adults were inversely proportional to dietary azadirachtin concentration, and reduced by 50% relative to controls when larvae were fed a diet containing 10 ppm azadirachtin. However, there were no effects of azadirachtin on pheromone blend ratios. Our results suggest that reductions in fecundity and pheromone titer in O. furnacalis are associated with alterations in lipid metabolism by azadirachtin, although these effects are not linked to a reduction in consumption.

•We developed a dual-luciferase UPR reporter system.•The system can be used to monitor UPR activation in live cells of the yeast Saccharomyces cerevisiae.•The vector takes advantage of the HAC1 intron and its unconventional splicing-regulation mechanism.•This HAC1-based dual-luciferase reporter vector can be used to monitor UPR in live cells with high sensitivity.Unfolded protein response (UPR) is an important cellular phenomenon induced by over-accumulation of unfolded proteins in the endoplasmic reticulum (ER) lumen. ER stress and UPR are implicated in human diseases such as diabetes, atherosclerosis and neurodegenerative diseases. Current methods for measuring ER stress levels and UPR activation usually include cells lysis and other complicated procedures such as reverse transcription-PCR (RT-PCR). These methods typically have low sensitivity and are not suitable for live detection. In this study, we developed a dual-luciferase gene reporter system to monitor UPR activation in live cells of the yeast Saccharomyces cerevisiae by taking advantage of the HAC1 intron and its unconventional splicing-regulation mechanism. We showed that this reporter can be used to monitor UPR in live cells with high sensitivity.