Hasil untuk "Microscopy"

Dane W. de Quilettes, S. Vorpahl, S. Stranks et al.

D. Larson, W. Zipfel, Rebecca M. Williams et al.

Daniele Pirone, Giusy Giugliano, Michela Schiavo et al.

Virtual staining is the current state-of-the-art computational technique to cleverly enhance intracellular specificity in unstained biological samples by using convolutional neural networks (CNNs) trained on co-registered pairs of unstained/stained images. While effective, this approach suffers from unpredictable biases inherent to fluorescence microscopy and encounters challenges when applied to flow cytometry data as it would require accurate co-registration on a huge number of images. Here, we present a novel method that exploits for the first time a Holotomography-driven learning to completely eliminate the need for co-registration. We demonstrate that training a CNN on a stain-free dataset of 3D refractive index tomograms of flowing cells unlocks stain-free intracellular specificity for the first time in quantitative phase imaging flow cytometry. This self-supervised solution, by circumventing the critical obstacle of fluorescence co-registration, opens unprecedented perspectives for label-free, high-throughput imaging flow cytometry, offering a powerful new paradigm for advanced 2D and 3D single-cell analysis.

Daniil Shirokiy, Andrey Bukaemskiy, Maximilian Henkes et al.

Abstract Cr-doped UO₂ fuels are increasingly adopted for their superior in-reactor performance compared to undoped UO₂, but their spent fuel behaviour, particularly potential Cr speciation and fission product reactivity, remains poorly understood. This investigation has used high energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy to examine speciation of Cr and Pr/Gd within 200 ppm Cr-doped (U4.4+ 0.7Pr3+ 0.3)O2-x and 200 ppm Cr-doped (U4.4+ 0.7Gd3+ 0.3)O2-x compounds. Despite both being UO2 soluble and undersaturated, analysis indicates that Cr3+ and Pr3+/Gd3+ form perovskite type (Pr3+/Gd3+)Cr3+O3 phases, consistent with classical “grey phases” of spent fuel. The radiation tolerance of these phases was examined via swift heavy ion irradiations of PrCrO3 and GdCrO3 compounds where electron microscopy and grazing incidence synchrotron diffraction indicate significant amorphization but retention of the crystal structure. The investigation highlights the pertinence of considering the chemistry of dopants used for nuclear fuel enhancements regarding their speciation during irradiation and subsequent occurrence within spent fuel.

H. Mollenhauer

Angelika Till, Silvia Ulrich, David J. Cantrill et al.

Until now investigations on the ultrastructural characteristics of <i>Pseudanthus</i> pollen using transmission electron microscopy (TEM) were limited. The aims of this study were as follows: (1) to present the first comprehensive TEM-based analysis of <i>Pseudanthus</i> pollen; (2) to provide a holistic morphological and ultrastructural description of <i>Pseudanthus</i> pollen; (3) to compare <i>Pseudanthus</i> pollen to that from other Picrodendraceae and closely related families; (4) to clarify intraspecific, interspecific, intrafamilial, and interfamilial character traits of <i>Pseudanthus</i> pollen in relation to that from related genera/families; and (5) to conclude if <i>Pseudanthus</i> pollen could potentially be identified in the palynological record. <i>Pseudanthus</i> pollen samples were collected from anthetic flowers and prepared according to standard methods for investigation with TEM. Interpretations of pollen ultrastructure in other Picrodendraceae and closely related families were based on previously published TEM micrographs. The pollen ultrastructure from six out of nine <i>Pseudanthus</i> species is described here for the first time. By integrating LM, SEM, and TEM techniques, this study offers a holistic perspective on the genus’s pollen morphology and ultrastructural range. It also illuminates the intraspecific and interspecific pollen morphological and ultrastructural diversity within <i>Pseudanthus</i> and how it differentiates from other Picrodendraceae as well as the Euphorbiaceae and Phyllanthaceae. The combined morphological and ultrastructural traits of <i>Pseudanthus</i> pollen render it unique among Picrodendraceae and differentiate it from the pollen of closely related families. This opens the door for future paleopalynological investigations, but until now <i>Pseudanthus</i> pollen has not been reported from the fossil record.

Yiyue Jiang, Ying Wang, YunXue Bai et al.

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global health challenge, particularly associated with serious infections such as bacteremia. Lipoglycopeptide antibiotics, including vancomycin, dalbavancin, and daptomycin, are critical in MRSA treatment. In this study, we analyzed two MRSA isolates (XF1 and XF2) from a bacteremia patient treated with vancomycin. Antimicrobial susceptibility testing revealed that XF1 was sensitive to vancomycin, dalbavancin, and daptomycin, whereas XF2 exhibited 8- to 16-fold higher minimum inhibitory concentrations for these antibiotics, alongside a 4- to 8-fold reduction in resistance to β-lactam antibiotics, demonstrating the “β-lactam seesaw effect”. Whole-genome sequencing confirmed their isogenic nature (ST59-SCCmecIV-t172), identifying seven mutations in XF2, including those in walK (G223S), vraR (D88Y), clpX (P64L), and ltaS (L62P), as well as a frameshift mutation in mgt (S39fs), likely contributing to resistance. Transmission electron microscopy and autolysis assays demonstrated that XF2 had a thicker cell wall and a slower autolysis rate compared to XF1. Phenotypic analysis showed that XF2 exhibited reduced growth rate, diminished virulence, and enhanced biofilm formation compared to XF1. Gene expression analysis supported these findings, revealing significant alterations in pathways related to cell wall metabolism, autolysis, and virulence regulation. These adaptations highlight the genomic and phenotypic plasticity of MRSA under antibiotic pressure, enabling resistance and persistence. This study underscores the urgent need for enhanced surveillance and alternative therapeutic strategies, including exploiting the β-lactam seesaw effect, to combat lipoglycopeptide-nonsusceptible MRSA.

J. Luft

During the early phases of tissue sectioning for electron microscopy, virtually all of the standard cytological fixatives were tried. Of these, osmium tetroxide appeared to give the best preservation, and this was further improved by buffering the fixative solution at a slightly alkaline pH (Palade (1)). A variant developed by Dalton (2) contains Os04 in a chromate-dichromate system. Formalin has been used for special purposes for electron microscopy, and a fixative without OsO4 has been described by Low (3), consisting of a chromic acid-formaldehyde mixture. Potassium permanganate, or more specifically the permanganate ion, has occasionally been used as a fixative or stain in light microscopy (4). I t provides remarkable preservation of many cell components at the electron microscope level, as the following plates illustrate. The tissue fine structure looks similar to that following osmium treatment, thus rendering less likely the criticism that electron microscopists are merely seeing artifacts of osmium fixation. Besides preserving fine structure, permanganate fixation enhances tissue density

K. Shreya Shetty, Marina Koland, Ashwini, M. Marina

This study aimed to develop a topical nanoparticulate form of trigonelline to enhance delivery to hair follicles and promote hair growth, addressing the limitations of conventional topicals. Trigonelline nanocrystals were synthesized using sonoprecipitation and optimized through the Box–Behnken design. The optimized nanocrystals were analyzed using scanning and transmission electron microscopy. In vitro permeation and in-vivo skin irritation tests were conducted. The effect on hair length and density was evaluated in cyclophosphamide-induced alopecia in Wistar rats. The optimized nanocrystals had a particle size of 142.7 nm, a polydispersity index of 0.137, and a zeta potential of −25.9 mV. The topical cream contained 79.0% drug. In vitro studies showed higher flux with high Trigonelline loading. In vivo tests indicated the product was innocuous. Hair length and density were significantly greater (P < 0.01) in the nanocrystal-treated group compared to controls and commercial hair oil, but not greater than the Minoxidil group after 30 days. Nanocrystal-based trigonelline formulations show promise for treating alopecia, potentially offering an alternative to minoxidil and finasteride.

Marcin K. Dziuba, Kristina M. McIntire, Kensuke Seto et al.

ABSTRACT The impacts of microsporidia on host individuals are frequently subtle and can be context dependent. A key example of the latter comes from a recently discovered microsporidian symbiont of Daphnia, the net impact of which was found to shift from negative to positive based on environmental context. Given this, we hypothesized low baseline virulence of the microsporidian; here, we investigated the impact of infection on hosts in controlled conditions and the absence of other stressors. We also investigated its phylogenetic position, ecology, and host range. The genetic data indicate that the symbiont is Ordospora pajunii, a newly described microsporidian parasite of Daphnia. We show that O. pajunii infection damages the gut, causing infected epithelial cells to lose microvilli and then rupture. The prevalence of this microsporidian could be high (up to 100% in the lab and 77% of adults in the field). Its overall virulence was low in most cases, but some genotypes suffered reduced survival and/or reproduction. Susceptibility and virulence were strongly host-genotype dependent. We found that North American O. pajunii were able to infect multiple Daphnia species, including the European species Daphnia longispina, as well as Ceriodaphnia spp. Given the low, often undetectable virulence of this microsporidian and potentially far-reaching consequences of infections for the host when interacting with other pathogens or food, this Daphnia–O. pajunii symbiosis emerges as a valuable system for studying the mechanisms of context-dependent shifts between mutualism and parasitism, as well as for understanding how symbionts might alter host interactions with resources.IMPORTANCEThe net outcome of symbiosis depends on the costs and benefits to each partner. Those can be context dependent, driving the potential for an interaction to change between parasitism and mutualism. Understanding the baseline fitness impact in an interaction can help us understand those shifts; for an organism that is generally parasitic, it should be easier for it to become a mutualist if its baseline virulence is relatively low. Recently, a microsporidian was found to become beneficial to its Daphnia hosts in certain ecological contexts, but little was known about the symbiont (including its species identity). Here, we identify it as the microsporidium Ordospora pajunii. Despite the parasitic nature of microsporidia, we found O. pajunii to be, at most, mildly virulent; this helps explain why it can shift toward mutualism in certain ecological contexts and helps establish O. pajunii is a valuable model for investigating shifts along the mutualism-parasitism continuum.

Ecco Staller, Loïc Carrique, Olivia C. Swann et al.

Abstract Avian influenza A viruses (IAVs) pose a public health threat, as they are capable of triggering pandemics by crossing species barriers. Replication of avian IAVs in mammalian cells is hindered by species-specific variation in acidic nuclear phosphoprotein 32 (ANP32) proteins, which are essential for viral RNA genome replication. Adaptive mutations enable the IAV RNA polymerase (FluPolA) to surmount this barrier. Here, we present cryo-electron microscopy structures of monomeric and dimeric avian H5N1 FluPolA with human ANP32B. ANP32B interacts with the PA subunit of FluPolA in the monomeric form, at the site used for its docking onto the C-terminal domain of host RNA polymerase II during viral transcription. ANP32B acts as a chaperone, guiding FluPolA towards a ribonucleoprotein-associated FluPolA to form an asymmetric dimer—the replication platform for the viral genome. These findings offer insights into the molecular mechanisms governing IAV genome replication, while enhancing our understanding of the molecular processes underpinning mammalian adaptations in avian-origin FluPolA.

B. Boycott, J. Dowling, H. Kolb

mehdi taghdiri, Shahrban Dadari Doolabi

Recently, considerable attention has been focused on heteropoly acids including their anions (polyoxometalates or POMs) due to many advantages such as simple preparation, high reactivity, non-corrosive, non-pollutant and excellent stability. POMs have been used as photocatalysts for the destruction of dyes. Discharge of wastewater of synthetic dyes to environment affects both living organisms of aquatic ecosystems and human health due to toxicity and carcinogenicity. Consequently, treatment of dye-contaminated wastewaters with decontamination processes is necessary before their discharge. In this study, magnetic activated carbon nanoparticles (MAC) were coated with an organic hybrid of phosphotungstic acid that makes MAC suitable for adsorption and photocatalytic degradation of dyes. The prepared composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermal analyses, scanning electron microscopy and vibrating sample magnetometer. Dye adsorption and photocatalytic properties of composite was examined by studying the decolorization of model dyes methylene blue (MB), methyl orange (MO) and their mixture solutions. The results show that the composite can selectively adsorb MB molecules from binary mixtures of MB/MO. While the visible light is not able to degrade alone MO solution in the presence of composite, it degrades the MO mixed with MB solution. The composite is, unlike MAC, a good photocatalyst in the degradation of dyes under sunlight and visible irradiation and can be separated by magnet, recovered and reused. Removal is via combination of adsorption and then photocatalytic degradation through direct oxidation by composite.

Katterine Salazar, Katterine Salazar, Nery Jara et al.

Different studies have established the fundamental role of vitamin C in proliferation, differentiation, and neurogenesis in embryonic and adult brains, as well as in in vitro cell models. To fulfill these functions, the cells of the nervous system regulate the expression and sorting of sodium-dependent vitamin C transporter 2 (SVCT2), as well as the recycling of vitamin C between ascorbic acid (AA) and dehydroascorbic acid (DHA) via a bystander effect. SVCT2 is a transporter preferentially expressed in neurons and in neural precursor cells. In developmental stages, it is concentrated in the apical region of the radial glia, and in adult life, it is expressed preferentially in motor neurons of the cerebral cortex, starting on postnatal day 1. In neurogenic niches, SVCT2 is preferentially expressed in precursors with intermediate proliferation, where a scorbutic condition reduces neuronal differentiation. Vitamin C is a potent epigenetic regulator in stem cells; thus, it can induce the demethylation of DNA and histone H3K27m3 in the promoter region of genes involved in neurogenesis and differentiation, an effect mediated by Tet1 and Jmjd3 demethylases, respectively. In parallel, it has been shown that vitamin C induces the expression of stem cell-specific microRNA, including the Dlk1–Dio3 imprinting region and miR-143, which promotes stem cell self-renewal and suppresses de novo expression of the methyltransferase gene Dnmt3a. The epigenetic action of vitamin C has also been evaluated during gene reprogramming of human fibroblasts to induced pluripotent cells, where it has been shown that vitamin C substantially improves the efficiency and quality of reprogrammed cells. Thus, for a proper effect of vitamin C on neurogenesis and differentiation, its function as an enzymatic cofactor, modulator of gene expression and antioxidant is essential, as is proper recycling from DHA to AA by various supporting cells in the CNS.

Fang Hao, Xueyu Liu, Ming Li et al.

Membranous nephropathy is one of the most prevalent conditions responsible for nephrotic syndrome in adults. It is clinically nonspecific and mainly diagnosed by kidney biopsy pathology, with three prevalent techniques: light microscopy, electron microscopy, and immunofluorescence microscopy. Manual observation of glomeruli one by one under the microscope is very time-consuming, and there are certain differences in the observation results between physicians. This study makes use of whole-slide images scanned by a light microscope as well as immunofluorescence images to classify patients with membranous nephropathy. The framework mainly includes a glomerular segmentation module, a confidence coefficient extraction module, and a multi-modal fusion module. This framework first identifies and segments the glomerulus from whole-slide images and immunofluorescence images, and then a glomerular classifier is trained to extract the features of each glomerulus. The results are then combined to produce the final diagnosis. The results of the experiments show that the F1-score of image classification results obtained by combining two kinds of features, which can reach 97.32%, is higher than those obtained by using only light-microscopy-observed images or immunofluorescent images, which reach 92.76% and 93.20%, respectively. Experiments demonstrate that considering both WSIs and immunofluorescence images is effective in improving the diagnosis of membranous nephropathy.

Oscar Daniel Salvioni Recalde, Stefanía Fraenkel, María José Tintel et al.

Surra is a disease caused by the hemoflagellate pathogen Trypanosoma evansi which affects a wide variety of mammals. The only cases reported of the presence of T. evansi in Paraguay were identified in samples from horses and capybaras and they were detected by light microscopy in the 19th century. The aim of this study is to report three autochthonous cases of canine trypanosomiasis caused by T. evansi, for the first time in the country, using molecular techniques and their application for the differential diagnosis of trypanosomatids species. The technique implemented was real-time PCR-HRM, amplifying a fragment of the hsp70 gene, using a pair of primers initially used to discriminate Leishmania species. This is the first report on the usage of these primers to detect T. evansi through HRM analysis, which allows the differentiation of trypanosomatids species simultaneously, making it an efficient tool for differential diagnosis.

Biyao Cheng, Shuming Yang, Wei Li et al.

Abstract Carbon nanotubes (CNTs) can be used as atomic force microscopy (AFM) tips for high-resolution scanning due to their small diameter, high aspect ratio and outstanding wear resistance. However, previous approaches for fabricating CNT probes are complex and poorly controlled. In this paper, we introduce a simple method to selectively fabricate a single CNT on an AFM tip by controlling the trigger threshold to adjust the amount of growth solution attached to the tip. The yield rate is over 93%. The resulting CNT probes are suitable in length, without the need for a subsequent cutting process. We used the CNT probe to scan the complex nanostructure with a high aspect ratio, thereby solving the long-lasting problem of mapping complex nanostructures.

Juhyoun Kwak, A. Bard

E. Mcdowell, B. Trump

R. Horne