Ovarian cancer cell fate regulation by the dynamics between saturated and unsaturated fatty acids.

Fatty acids are an important source of energy and a key component of phospholipids in membranes and organelles. Saturated fatty acids (SFAs) are converted into unsaturated fatty acids (UFAs) by stearoyl Co-A desaturase (SCD), an enzyme active in cancer. Here, we studied how the dynamics between SFAs and UFAs regulated by SCD impacts ovarian cancer cell survival and tumor progression. SCD depletion or inhibition caused lower levels of UFAs vs. SFAs and altered fatty acyl chain plasticity, as demonstrated by lipidomics and stimulated Raman scattering (SRS) microscopy. Further, increased levels of SFAs resulting from SCD knockdown triggered endoplasmic reticulum (ER) stress response with brisk activation of IRE1α/XBP1 and PERK/eIF2α/ATF4 axes. Disorganized ER membrane was visualized by electron microscopy and SRS imaging in ovarian cancer cells in which SCD was knocked down. The induction of long-term mild ER stress or short-time severe ER stress by the increased levels of SFAs and loss of UFAs led to cell death. However, ER stress and apoptosis could be readily rescued by supplementation with UFAs and reequilibration of SFA/UFA levels. The effects of SCD knockdown or inhibition observed in vitro translated into suppression of intraperitoneal tumor growth in ovarian cancer xenograft models. Furthermore, a combined intervention using an SCD inhibitor and an SFA-enriched diet initiated ER stress in tumors growing in vivo and potently blocked their dissemination. In all, our data support SCD as a key regulator of the cancer cell fate under metabolic stress and point to treatment strategies targeting the lipid balance.

Effects of Lactobacillus plantarum and Saccharomyces cerevisiae co-fermentation on the structure and flavor of wheat noodles.

BACKGROUND: Although traditional fermented noodles possess high eating quality, it is difficult to realize large-scale industrialization as a result of the complexity of spontaneous fermentation. In present study, commercial Lactobacillus plantarum and Saccharomyces cerevisiae were applied in the preparation of fermented noodles. RESULTS: The changes in the structural characteristics and aroma components of noodles after fermentation were investigated via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), low-field magenetic resonance imaging, electronic nose, and simultaneous distillation and extraction/gas chromatography-mass spectrometry (GC-MS) analysis. SEM images revealed that co-fermentation of the L. plantarum and S. cerevisiae for 10-40 min enhanced the continuity of the gluten network and promoted the formation of pores. FTIR spectra analysis showed that the co-fermentation increased significantly (P < 0.05) the proportion of α-helices of noodles gluten protein, enhancing the orderliness of the molecular structure of protein. After fermentation for 10-40 min, the signal density of hydrogen protons increased from the surface to the core, indicating that the water in the noodles migrated inward during a short fermentation process. The results of multivariate statistical analysis demonstrated that the main aroma differences between unfermented and fermented noodles were mainly in hydrocarbons, aromatic compounds and inorganic sulfides. GC-MS analysis indicated that the main volatile compounds detected were 2, 4-di-tert-butylphenol, bis (2-ethylhexyl) adipate, butyl acetate, dibutyl phthalate, dioctyl terephthalate, bis (2-ethylhexyl) phthalate, pentanol and 2-pentylfuran, etc. CONCLUSION: Co-fermentation with L. plantarum and S. cerevisiae improved the structure of gluten network and imparted more desirable volatile components to wheat noodles. © 2022 Society of Chemical Industry.

A Double Mutation in the Conserved Motifs of the Helper Component Protease of Papaya Leaf Distortion Mosaic Virus for the Generation of a Cross-Protective Attenuated Strain.

Potyviral helper component protease (HC-Pro), as a major determinant of symptom expression in susceptible plants, is a likely target candidate in the production of attenuated strains for cross-protection. In this study, single or double mutations of Lys (K) to Glu (E) in the Lys-Ile-Thr-Cys motif and Arg (R) to Ile (I) in the Phe-Arg-Asn-Lys motif of the HC-Pro from the severe papaya leaf distortion mosaic virus strain DF (PLDMV-DF) reduced symptom expression and virus accumulation in infected papaya (Carica papaya) plants. The papaya plants infected with the attenuated double mutant of PLDMV-EI presented as symptomless. PLDMV-EI provided effective protection against PLDMV-DF infection in three papaya cultivars and had no effect on plant growth and development. Our result showed that PLDMV-EI is a promising mild strain for the practical use of cross-protection in the field.

Distinct functions of diaphanous-related formins regulate HIV-1 uncoating and transport.

Diaphanous (Dia)-related formins (DRFs) coordinate cytoskeletal remodeling by controlling actin nucleation and microtubule (MT) stabilization to facilitate processes such as cell polarization and migration; yet the full extent of their activities remains unknown. Here, we uncover two discrete roles and functions of DRFs during early human immunodeficiency virus type 1 (HIV-1) infection. Independent of their actin regulatory activities, Dia1 and Dia2 facilitated HIV-1-induced MT stabilization and the intracellular motility of virus particles. However, DRFs also bound in vitro assembled capsid-nucleocapsid complexes and promoted the disassembly of HIV-1 capsid (CA) shell. This process, also known as "uncoating," is among the most poorly understood stages in the viral lifecycle. Domain analysis and structure modeling revealed that regions of Dia2 that bound viral CA and mediated uncoating as well as early infection contained coiled-coil domains, and that these activities were genetically separable from effects on MT stabilization. Our findings reveal that HIV-1 exploits discrete functions of DRFs to coordinate critical steps in early infection and identifies Dia family members as regulators of the poorly understood process of HIV-1 uncoating.

Removal of Alternaria mycotoxins from aqueous solution by inactivated yeast powder.

BACKGROUND: Alternariol (AOH) and alternariol monomethyl ether (AME), produced by Alternaria spp., are the two mycotoxins with the highest outbreak rates in food systems. The purpose of this study was to investigate the removal of AOH and AME from aqueous solutions by inactivated yeast cells. The effects of strains, yeast powder amount, temperature, and pH were evaluated. The kinetics of AOH and AME adsorption on inactivated yeast cells was fitted with four models and a release assay was carried out. RESULTS: All three tested yeasts could remove AOH and AME. GIM 2.119 was the most effective strain. The reduction rate of both AOH and AME could be as much as 100% with 40 g‧L-1 of yeast powder. For both mycotoxins, pH = 9 was the best environment for toxin removal. The pseudo-second-order kinetic model was the best model, with R2 ranging from 0.989 to 0.999. However, the R2 of the pseudo-first-order and Elovich models was also relatively high. Alternariol and AME could be partially eluted by methanol and acetonitrile. CONCLUSION: The inactivated yeast cells could effectively remove AOH and AME. This was best fitted by the pseudo-second-order model. The release assay suggested that the adsorption of Alternaria mycotoxins was partially reversible. The results of this study provide a theoretical basis for the removal of Alternaria mycotoxins from food systems and are useful for the investigation of the mechanisms involved in mycotoxin adsorption by inactivated yeast cells. © 2020 Society of Chemical Industry.

Three-dimensional super-resolved live cell imaging through polarized multi-angle TIRF.

Measuring three-dimensional nanoscale cellular structures is challenging, especially when the structure is dynamic. Owing to the informative total internal reflection fluorescence (TIRF) imaging under varied illumination angles, multi-angle (MA) TIRF has been examined to offer a nanoscale axial and a subsecond temporal resolution. However, conventional MA-TIRF still performs badly in lateral resolution and fails to characterize the depth image in densely distributed regions. Here, we emphasize the lateral super-resolution in the MA-TIRF, exampled by simply introducing polarization modulation into the illumination procedure. Equipped with a sparsity and accelerated proximal algorithm, we examine a more precise 3D sample structure compared with previous methods, enabling live cell imaging with a temporal resolution of 2 s and recovering high-resolution mitochondria fission and fusion processes. We also shared the recovery program, which is the first open-source recovery code for MA-TIRF, to the best of our knowledge.

Nonlinear Focal Modulation Microscopy.

We demonstrate nonlinear focal modulation microscopy (NFOMM) to achieve superresolution imaging. Traditional approaches to superresolution that utilize point scanning often rely on spatially reducing the size of the emission pattern by directly narrowing (e.g., through minimizing the detection pinhole in Airyscan, Zeiss) or indirectly peeling its outer profiles [e.g., through depleting the outer emission region in stimulated emission depletion (STED) microscopy]. We show that an alternative conceptualization that focuses on maximizing the optical system's frequency shifting ability offers advantages in further improving resolution while reducing system complexity. In NFOMM, a spatial light modulator and a suitably intense laser illumination are used to implement nonlinear focal-field modulation to achieve a transverse spatial resolution of ∼60 nm (∼λ/10). We show that NFOMM is comparable with STED microscopy and suitable for fundamental biology studies, as evidenced in imaging nuclear pore complexes, tubulin and vimentin in Vero cells. Since NFOMM is readily implemented as an add-on module to a laser-scanning microscope, we anticipate wide utility of this new imaging technique.

Profile of siRNAs derived from green fluorescent protein (GFP)-tagged Papaya leaf distortion mosaic virus in infected papaya plants.

We used green fluorescent protein (GFP)-tagged Papaya leaf distortion mosaic virus (PLDMV-GFP) to track PLDMV infection by fluorescence. The virus-derived small interfering RNAs (vsiRNAs) of PLDMV-GFP were characterized from papaya plants by next-generation sequencing. The foreign GFP gene inserted into the PLDMV genome was also processed as a viral gene into siRNAs by components involved in RNA silencing. The siRNAs derived from PLDMV-GFP accumulated preferentially as 21- and 22-nucleotide (nt) lengths, and most of the 5'-terminal ends were biased towards uridine (U) and adenosine (A). The single-nucleotide resolution map revealed that vsiRNAs were heterogeneously distributed throughout the PLDMV-GFP genome, and vsiRNAs derived from the sense strand were more abundant than those from the antisense strand. The hotspots were mainly distributed in the P1 and GFP coding region of the antisense strand. In addition, 979 papaya genes targeted by the most abundant 1000 PLDMV-GFP vsiRNAs were predicted and annotated using GO and KEGG classification. Results suggest that vsiRNAs play key roles in PLDMV-papaya interactions. These data on the characterization of PLDMV-GFP vsiRNAs will help to provide insight into the function of vsiRNAs and their host target regulation patterns.

3D point scanning super-resolution microscopy via polarization modulation.

We report a new approach to achieving super-resolution in point-scanning microscopy through polarization modulation for the first time, to the best of our knowledge. By modulating linearly polarized incident light, the emission extent of fluorescent dyes changes periodically, adding sparsity in each recording, which contributes to the super-resolution reconstruction. To recover the super-resolution result, a sparse penalty-based deconvolution method is implemented onto the polarization-modulated dataset subsequently. By simply inserting a vortex half-wave retarder into a typical confocal microscope, we obtain the super-resolution experimental results of both nuclear pore complex proteins and tubulins in vero cells, which evidence a sub-diffraction resolution of λ/5. In addition, three-dimensional (3D) super-resolution on spatial distributed single molecules is simulated, where the significant resolution improvement in both lateral and axial directions further confirms its capacity in 3D imaging applications. Considering no constraint on fluorescence dyes and easy implementation in a point-scanning microscope, we envision that the polarization-modulated confocal microscope would be a helpful alternative in biological imaging.

Resolution-enhanced SOFI via structured illumination.

By analyzing the statistics of the temporal fluctuations from the blinking emitters, super-resolution fluctuation imaging (SOFI) achieves super-resolution while imposing fewer constraints on the blinking behavior of the probes and is more suitable for low signal-to-noise ratio acquisition than localization methods. However, determined by the square root of cumulation orders, the resolution improvement of SOFI highly restricts its promotion into high-resolution observations. In this Letter, abandoning the default flat illumination in stochastic imaging methods, we introduce structured illumination (SI) (e.g., Gaussian or sinusoidal pattern) into SOFI (SI-SOFI) to render greatly enhanced resolution. Through simulation with parameters of both real acquisition procedures and microscope properties, we examine the feasibility of SI-SOFI and obtain a resolution improvement of four-six folds at just second-order cumulation compared to wide-field imaging. In addition, a practical pathway for the SI-SOFI reconstruction is offered.

Digital micromirror device-based common-path quantitative phase imaging.

We propose a novel common-path quantitative phase imaging (QPI) method based on a digital micromirror device (DMD). The DMD is placed in a plane conjugate to the objective back-aperture plane for the purpose of generating two plane waves that illuminate the sample. A pinhole is used in the detection arm to filter one of the beams after sample to create a reference beam. Additionally, a transmission-type liquid crystal device, placed at the objective back-aperture plane, eliminates the specular reflection noise arising from all the "off" state DMD micromirrors, which is common in all DMD-based illuminations. We have demonstrated high sensitivity QPI, which has a measured spatial and temporal noise of 4.92 nm and 2.16 nm, respectively. Experiments with calibrated polystyrene beads illustrate the desired phase measurement accuracy. In addition, we have measured the dynamic height maps of red blood cell membrane fluctuations, showing the efficacy of the proposed system for live cell imaging. Most importantly, the DMD grants the system convenience in varying the interference fringe period on the camera to easily satisfy the pixel sampling conditions. This feature also alleviates the pinhole alignment complexity. We envision that the proposed DMD-based common-path QPI system will allow for system miniaturization and automation for a broader adaption.

Resolution enhancement of saturated fluorescence emission difference microscopy.

Fluorescence emission difference microscopy (FED) obtains resolution-enhanced images by subtracting acquired solid and doughnut confocal images. Because of the mismatch of the outer contours of the two subtraction components, negative values are inevitable in the conventional FED method, giving rise to deformations. In this study, by using a saturation effect, we obtain imaging results with a profile-extended solid and center-shrunken doughnut point spread function. Owing to the nonlinear effect, two better-matched saturated images not only eliminate the deformations, but also enhance the resolving ability and signal to noise ratio compared to conventional FED. Simulations based on the saturated model of rhodamine 6G, as well as experiments on biological samples, are presented to verify the capability of the proposed concept, while experimental results show the unprecedented resolving ability of the saturated FED method.

A loop-mediated isothermal amplification assay for the visual detection of duck circovirus.

BACKGROUND: Duck circovirus (DuCV) infection in farmed ducks is associated with growth problems or retardation syndromes. Rapid identification of DuCV infected ducks is essential to control DuCV effectively. Therefore, this study aims to develop of an assay for DuCV to be highly specific, sensitive, and simple without any specialized equipment. METHODS: A set of six specific primers was designed to target the sequences of the Rep gene of DuCV, and A loop-mediated isothermal amplification (LAMP) assay were developed and the reaction conditions were optimized for rapid detection of DuCV. RESULTS: The LAMP assay reaction was conducted in a 62°C water bath condition for 50 min. Then the amplification products were visualized directly for color changes. This LAMP assay is highly sensitive and able to detect twenty copies of DuCV DNA. The specificity of this LAMP assay was supported by no cross-reaction with other duck pathogens. CONCLUSION: This LAMP method for DuCV is highly specific and sensitive and can be used as a rapid and direct diagnostic assay for testing clinical samples.

A novel anti-inflammatory strategy for myocardial ischemia-reperfusion in rats with cinnamamide derivative compound 7.

Reperfusion after myocardial ischemia would aggravate myocardial structural and functional damage, known as myocardial ischemia-reperfusion (MI/R) injury. Cinnamamide derivatives have been reported to exert cardioprotective effects, and we have previously reported that compound 7 played a role in cardioprotection against MI/R via anti-inflammatory effect. However, exact mechanism underlying such beneficial action of compound 7 is still unclear. The protective effect of compound 7 was determined in H9c2 cells under H2O2 stimulation with or without nigerin (NLRP3 activator). Electrocardiogram, echocardiography, myocardial infarction size, histopathology and serum biochemical assay were performed in MI/R rats. Metabolomics in vivo and mRNA or protein levels of NLRP3, ASC, cleaved caspase-1 and its downstream IL-18 and IL-1ß were detected both in vitro and in vivo. Compound 7 significantly ameliorate H2O2-induced cardiomyocyte damage, which was supported by in vivo data determined by improved left ventricular systolic function and histopathological changes, reduced myocardial infarction area and cellular apoptosis in heart tissue. Cardiac differential metabolites demonstrated that compound 7 indeed altered the cardiac reprogramming of inflammation-related metabolites, which was evidenced by down-regulated cardiac inflammation by compound 7. Additionally, compound 7 alleviated myocardial injury by inhibiting the NLRP3 pathway rather than other members of the inflammasome both in vitro and in vivo, which was further evidenced by CETSA assay. Whereas, nigerin blocked the inhibitory activity of compound 7 against NLRP3. Cinnamamide derivative compound 7 ameliorated MI/R injury by inhibiting inflammation via NLRP3.

E2F1 mediates competition, proliferation and response to cisplatin in cohabitating resistant and sensitive ovarian cancer cells.

Background: Tumor heterogeneity is one of the key factors leading to chemo-resistance relapse. It remains unknown how resistant cancer cells influence sensitive cells during cohabitation and growth within a heterogenous tumors. The goal of our study was to identify driving factors that mediate the interactions between resistant and sensitive cancer cells and to determine the effects of cohabitation on both phenotypes. Methods: We used isogenic ovarian cancer (OC) cell lines pairs, sensitive and resistant to platinum: OVCAR5 vs. OVCAR5 CisR and PE01 vs. PE04, respectively, to perform long term direct culture and to study the phenotypical changes of the interaction of these cells. Results: Long term direct co-culture of sensitive and resistant OC cells promoted proliferation (p < 0.001) of sensitive cells and increased the proportion of cells in the G1 and S cell cycle phase in both PE01 and OVCAR5 cells. Direct co-culture led to a decrease in the IC50 to platinum in the cisplatin-sensitive cells (5.92 µM to 2.79 µM for PE01, and from 2.05 µM to 1.51 µM for OVCAR5). RNAseq analysis of co-cultured cells showed enrichment of Cell Cycle Control, Cyclins and Cell Cycle Regulation pathways. The transcription factor E2F1 was predicted as the main effector responsible for the transcriptomic changes in sensitive cells. Western blot and qRT-PCR confirmed upregulation of E2F1 in co-cultured vs monoculture. Furthermore, an E2F1 inhibitor reverted the increase in proliferation rate induced by co-culture to baseline levels. Conclusion: Our data suggest that long term cohabitation of chemo-sensitive and -resistant cancer cells drive sensitive cells to a higher proliferative state, more responsive to platinum. Our results reveal an unexpected effect caused by direct interactions between cancer cells with different proliferative rates and levels of platinum resistance, modelling competition between cells in heterogeneous tumors.

On the use of deep learning for phase recovery.

Phase recovery (PR) refers to calculating the phase of the light field from its intensity measurements. As exemplified from quantitative phase imaging and coherent diffraction imaging to adaptive optics, PR is essential for reconstructing the refractive index distribution or topography of an object and correcting the aberration of an imaging system. In recent years, deep learning (DL), often implemented through deep neural networks, has provided unprecedented support for computational imaging, leading to more efficient solutions for various PR problems. In this review, we first briefly introduce conventional methods for PR. Then, we review how DL provides support for PR from the following three stages, namely, pre-processing, in-processing, and post-processing. We also review how DL is used in phase image processing. Finally, we summarize the work in DL for PR and provide an outlook on how to better use DL to improve the reliability and efficiency of PR. Furthermore, we present a live-updating resource ( https://github.com/kqwang/phase-recovery ) for readers to learn more about PR.

Protonation-mediated DNA tile self-assembly with nuclease resistance characteristic for signal-amplified detection of microRNAs.

DNA nanotechnology, developing rapidly in recent years, has unprecedented superiorities in biological application-oriented research including high programmability, convenient functionalization, reconfigurable structure, and intrinsic biocompatibility. However, the susceptibility to nucleases in the physiological environment has been an obstacle to applying DNA nanostructures in biological science research. In this study, a new DNA self-assembly strategy, mediated by double-protonated small molecules instead of classical metal ions, is developed to enhance the nuclease resistance of DNA nanostructures while retaining their integrality and functionality, and the relative application has been launched in the detection of microRNAs (miRNAs). Faced with low-abundance miRNAs, we integrate hybrid chain reaction (HCR) with DNA self-assembly in the presence of double-protonated small molecules to construct a chemiluminescence detection platform with nuclease resistance, which utilizes the significant difference of molecular weight between DNA arrays and false-positive products to effectively separate of reaction products and remove the detection background. This strategy attaches importance to the nucleic acid stability during the assay process via improving nuclease resistance while rendering the detection results for miRNAs more authentic and reliable, opening our eyes to more possibilities for the multiple applications of customized DNA nanostructures in biology, including bioassay, bioimaging, drug delivery, and cell modulation.

Mitochondrial dysfunction induced by honokiol.

Honokiol has shown the ability to induce the apoptosis of several different cancer cell lines. Considering that mitochondria are involved in apoptosis, the aim of the present work was to investigate the effects of honokiol on mitochondria. The effects of honokiol on the permeability of H⁺ and K⁺, membrane potential, membrane fluidity, respiration and swelling of mitochondria isolated from the rat liver were assessed. The results show that honokiol can significantly induce mitochondrial swelling, decrease membrane potential and affect the respiration of mitochondria. Meanwhile, honokiol does not have a direct effect on the mitochondrial permeability transition pore.

Complete genome sequence analysis of a duck circovirus from Guangxi pockmark ducks.

We report here the complete genomic sequence of a novel duck circovirus (DuCV) strain, GX1104, isolated from Guangxi pockmark ducks in Guangxi, China. The whole nucleotide sequence had the highest homology (97.2%) with the sequence of strain TC/2002 (GenBank accession number AY394721.1) and had a low homology (76.8% to 78.6%) with the sequences of other strains isolated from China, Germany, and the United States. This report will help to understand the epidemiology and molecular characteristics of Guangxi pockmark duck circovirus in southern China.