Electrochemical Monitoring of Real-Time Vesicle Dynamics Induced by Tau in a Confined Nanopipette.

The microtubule-associated protein tau participates in neurotransmission regulation via its interaction with synaptic vesicles (SVs). The precise nature and mechanics of tau's engagement with SVs, especially regarding alterations in vesicle dynamics, remain a matter of discussion. We report an electrochemical method using a synapse-mimicking nanopipette to monitor vesicle dynamics induced by tau. A model vesicle of ~30 nm is confined within a lipid-modified nanopipette orifice with a comparable diameter to mimic the synaptic lipid environment. Both tau and phosphorylated tau (p-tau) present two-state dynamic behavior in this biomimetic system, showing typical ionic current oscillation, induced by lipid-tau interaction. The results indicate that p-tau has a stronger affinity to the lipid vesicles in the confined environment, blocking the vesicle movement to a higher degree. Taken together, this method bridges a gap for sensing synaptic vesicle dynamics in a confined lipid environment, mimicking vesicle movement near the synaptic membrane. These findings contribute to understanding how different types of tau protein regulate synaptic vesicle motility and to underlying its functional and pathological behaviours in disease.

HFM-Tracker: a cell tracking algorithm based on hybrid feature matching.

Cell migration is known to be a fundamental biological process, playing an essential role in development, homeostasis, and diseases. This paper introduces a cell tracking algorithm named HFM-Tracker (Hybrid Feature Matching Tracker) that automatically identifies cell migration behaviours in consecutive images. It combines Contour Attention (CA) and Adaptive Confusion Matrix (ACM) modules to accurately capture cell contours in each image and track the dynamic behaviors of migrating cells in the field of view. Cells are firstly located and identified via the CA module-based cell detection network, and then associated and tracked via a cell tracking algorithm employing a hybrid feature-matching strategy. This proposed HFM-Tracker exhibits superiorities in cell detection and tracking, achieving 75% in MOTA (Multiple Object Tracking Accuracy) and 65% in IDF1 (ID F1 score). It provides quantitative analysis of the cell morphology and migration features, which could further help in understanding the complicated and diverse cell migration processes.

Highly Efficient Photosensitizers with Molecular Vibrational Torsion for Cancer Photodynamic Therapy.

The development of highly effective photosensitizers (PSs) for photodynamic therapy remains a great challenge at present. Most PSs rely on the heavy-atom effect or the spin-orbit charge-transfer intersystem crossing (SOCT-ISC) effect to promote ISC, which brings about additional cytotoxicity, and the latter is susceptible to the interference of solvent environment. Herein, an immanent universal property named photoinduced molecular vibrational torsion (PVT)-enhanced spin-orbit coupling (PVT-SOC) in PSs has been first revealed. PVT is verified to be a widespread intrinsic property of quinoid cyanine (QCy) dyes that occurs on an extremely short time scale (10-10 s) and can be captured by transient spectra. The PVT property can provide reinforced SOC as the occurrence of ISC predicted by the El Sayed rules (1ππ*-3nπ*), which ensures efficient photosensitization ability for QCy dyes. Hence, QTCy7-Ac exhibited the highest singlet oxygen yield (13-fold higher than that of TCy7) and lossless fluorescence quantum yield (ΦF) under near-infrared (NIR) irradiation. The preeminent photochemical properties accompanied by high biosecurity enable it to effectively perform photoablation in solid tumors. The revelation of this property supplies a new route for constructing high-performance PSs for achieving enhanced cancer phototherapy.

Confined Nanopipet as a Versatile Tool for Precise Single Cell Manipulation.

The precise manipulation of single cells plays a fundamental role for single cell measurement, which is crucial for understanding the diverse cellular mechanisms. Unusual single cell behavior could thus be identified by integrating with advanced analytical methods such as single cell omics, unraveling the intrinsic cellular heterogeneity hidden in ensemble measurements. Herein, this technical note reports a nanopipet-based versatile method for manipulation of an ultrasmall volume of liquid, which further enables the precise manipulation of single cells. Femtoliter volumes of cytoplasm were extracted from single living cells and analyzed by time-of-flight secondary ion mass spectrometry. Moreover, several kinds of exogenous components were injected simultaneously into a cell, offering a delicate tool for multi-imaging in single living cells.

The effects of short-term treatment of microcystin-LR on the insulin pathway in both the HL7702 cell line and livers of mice.

Our previous work indicated exposure of Human liver cell 7702 (HL7702) cells to Microcystin-leucine-arginine (MC-LR) for 24 hours can disrupt insulin (INS) signaling by the hyperphosphorylation of specific proteins. For further exploring the time-dependent effect posed by MC-LR on this pathway, in the current study, HL7702 cells together with mice were exposed to the MC-LR with different concentrations under short-term treatment, and then, protein phosphatase 2A (PP2A) activity and expression of proteins related to INS signaling, as well as the characteristics of their action in the liver, were investigated. The results indicated, in HL7702 cells with 0.5, 1, and 6 hours of treatment by MC-LR, PP2A activity showed an obvious decrease in a time and concentration-dependent manner. While the total protein level of Akt, glycogen synthase kinase 3 (GSK-3), and glycogen synthase remained unchanged, GSK-3 and Akt phosphorylation increased significantly. In livers of mice with 1 hour of intraperitoneal injection with MC-LR, a similar change in these proteins was observed. In addition, the levels of total IRS1 and p-IRS1 at serine sites showed decreasing and increasing trends,respectively, and the hematoxylin and eosin staining showed that liver tissues of mice in the maximum-dose group exhibited obvious hepatocyte degeneration and hemorrhage. Our results further proved that short-term treatment with MC-LR can inhibit PP2A activity and disrupt INS signaling proteins' phosphorylation level, thereby interfering with the INS pathway. Our findings provide a helpful understanding of the toxic effects posed by MC-LR on the glucose metabolism of liver via interference with the INS signaling pathway.

Microcystin-LR exposure disrupts the insulin signaling pathway in C2C12 mice muscle cell line.

Microcystin-LR (MC-LR) is a widely produced monocyclic heptapeptides in eutrophication waterbodies. MC-LR can induce various toxic effects in different cells. Our previous studies have found that MC-LR exposure can disrupt insulin signaling pathway in human liver cells (HL 7702). Skeletal muscle is one of the major organs for glucose disposal and responsive to insulin. However, the effects of MC-LR on insulin signaling pathway in muscle cells have not been fully explored. By using C2C12 mice muscle cells, this study aims to investigate the toxic effects of MC-LR in muscle cells with a focus on its effects on insulin signaling pathways. It was found that MC-LR entered into cells and inhibited protein phosphatase 2A (PP2A) significantly. Furthermore, MC-LR increased phosphorylation of Ser302, Ser307, Ser612 of insulin receptor substrate 1, AKT-Ser473, GSK3α-Ser21, and S6K1-Thr389 by inhibiting the activity of PP2A. The results in this study demonstrate that exposure of MCLR can disrupt the insulin pathway in muscle cells.

Microcystin-LR disrupts insulin signaling by hyperphosphorylating insulin receptor substrate 1 and glycogen synthase.

Microcystin-LR (MC-LR) is a cyanobacteria-derived heptapeptide that has been commonly characterized as a hepatotoxin. Although the liver is a primary organ in glucose homeostasis, the effect of MC-LR on glucose metabolism remains unclear. In this study, the human liver cell line HL7702 and ICR mice were exposed to various concentrations of MC-LR for 24 h, and the proteins involved in insulin signaling were investigated. The results showed that MC-LR treatment induced the hyperphosphorylation of insulin receptor substrate 1 (IRS1) at several serine sites, S307, S323, S636/639, and S1101 in HL7702 cells, and S302, S318, S632/635, and S1097 in mice livers. In addition, the activation of S6K1 was demonstrated to play an important role in MC-LR-induced IRS1 hyperphosphorylation at several serine sites. Decreased levels of total IRS1 were observed in the mice livers, but there was no significant change in HL7702 cells. MC-LR also induced glycogen synthase (GS) hyperphosphorylation at S641 (inactivating GS) both in vitro and in vivo, even glycogen synthase kinase 3, a well-known GS kinase, was inactivated after MC-LR treatment. Moreover, MC-LR could block insulin-induced GS activation. In addition, glucose transport in liver cells was not impacted by MC-LR either with or without insulin stimulation. Our study implies that MC-LR can interfere with the actions of IRS1 and GS in insulin signaling and may have a toxic effect on glucose metabolism in the liver.

[Adsorption of Pb2+ and Cd2+ from Aqueous Solution Using Vermicompost Derived from Cow Manure and Its Biochar].

Using vermicompost (CV) as raw material, its biochar (CVC350) was prepared at 350℃ and then their physio-biochemical properties were characterized. Furthermore, adsorption studies were performed in a batch system for removing Pb2+ and Cd2+ ions from solution. The characterization results revealed much higher surface area, smaller pore size, greater aromaticity and nonpolarity of CVC350 as compared to CV. Batch adsorption experiments revealed that both the adsorption of Pb2+ and Cd2+ onto CV or CVC350 fitted Langmuir isotherm model very well, and the maximum adsorption capacity of Pb2+ was in the order of CVC350>CV, but no difference was observed for the adsorption capacity of Cd2+ between CV and CVC350. The desorption studies showed that both CV and CVC350 had much higher adsorption rate for Pb2+ than that for Cd2+, and the Cd2+ adsorbed could be more easily desorbed from CV and CVC350 compared with that for the Pb2+ adsorbed. Both the dynamic adsorption process of Pb2+ onto CV and CVC350 was a rapid process, however, the adsorption process of Cd2+ onto CV and CVC350 could be separated into the first rapid step and the second slower step. The adsorption capacity of Pb2+ or Cd2+ onto CV and CVC350 was only affected by the much lower initial pH of the solution, besides, the adsorption capacity of Cd2+ onto CV and CVC350 was relatively more influenced by the initial pH compared with that of Pb2+. Moreover, FTIR analysis showed that the adsorption of Pb2+ and Cd2+on CV depended on the active sites such as aliphatic alcohol, aliphatic acid,carbonates as well as phosphate while that on CVC350 mainly relied on aromatic alcohol, aromatic acid and carbonates.