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Showing papers on "Ultrastructure published in 2022"



Journal ArticleDOI
TL;DR: In this article , the effects of n-ZnO on alfalfa under heat stress by various morpho-physiological and cellular approaches were investigated, and the results revealed that 90 mg L-1 N-ZO better prevented the heat stress-mediated membrane damage, lipid peroxidation and oxidative stress by stimulating antioxidant systems and enhancing osmolyte contents.

21 citations


Journal ArticleDOI
TL;DR: There was toxic effect in excess Mn on chickens, and HSPs and mitochondria were involved in the mechanism of dose-dependent injury caused by Mn in chicken testes, and new insights for Mn toxicity identification in animal husbandry production practice are provided.

21 citations


Journal ArticleDOI
01 Jan 2022
TL;DR: In this article , a super-resolution cryo-correlative light and electron microscopy (cryo-CLEM) method was used to characterize the bacterium Deinococcus radiodurans.
Abstract: Studying bacterial cell envelope architecture with electron microscopy is challenging due to the poor preservation of microbial ultrastructure with traditional methods. Here, we established and validated a super-resolution cryo-correlative light and electron microscopy (cryo-CLEM) method, and combined it with cryo-focused ion beam (cryo-FIB) milling and scanning electron microscopy (SEM) volume imaging to structurally characterize the bacterium Deinococcus radiodurans. Subsequent cryo-electron tomography (cryo-ET) revealed an unusual diderm cell envelope architecture with a thick layer of peptidoglycan (PG) between the inner and outer membranes, an additional periplasmic layer, and a proteinaceous surface S-layer. Cells grew in tetrads, and division septa were formed by invagination of the inner membrane (IM), followed by a thick layer of PG. Cytoskeletal filaments, FtsA and FtsZ, were observed at the leading edges of constricting septa. Numerous macromolecular complexes were found associated with the cytoplasmic side of the IM. Altogether, our study revealed several unique ultrastructural features of D. radiodurans cells, opening new lines of investigation into the physiology and evolution of the bacterium.

16 citations


Journal ArticleDOI
TL;DR: In this article , the authors investigated the light adaptation mechanisms of Heptacodium miconioides under different light intensity conditions: high light (HL), moderate light (ML), and low light (LL).

15 citations


Journal ArticleDOI
TL;DR: In this paper , a model for the construction of the abaxial epidermal primary cell wall is proposed, where the cell deposits successive layers of cellulose fibers at -45° and +45° relative to the cell's long axis and secretes the surrounding HG-rich meshing proximal to the plasma membrane, which then migrates to more distal regions of the cell wall.

14 citations


Posted ContentDOI
17 Apr 2022-bioRxiv
TL;DR: pan-Expansion Microscopy of tissue (pan-ExM-t), an all-optical mouse brain imaging method that combines ∼24-fold linear expansion of biological samples with fluorescent pan-staining of protein densities (providing EM-like ultrastructural context), and immunolabeling of protein targets (for molecular imaging).
Abstract: Understanding the molecular anatomy and neural connectivity of the brain requires imaging technologies that can map the 3D nanoscale distribution of specific proteins in the context of brain ultrastructure. Light and electron microscopy (EM) enable visualization of either specific labels or anatomical ultrastructure, but combining molecular specificity with anatomical context is challenging. Here, we present pan-Expansion Microscopy of tissue (pan-ExM-t), an all-optical mouse brain imaging method that combines ∼24-fold linear expansion of biological samples with fluorescent pan-staining of protein densities (providing EM-like ultrastructural context), and immunolabeling of protein targets (for molecular imaging). We demonstrate the versatility of this approach by imaging the established synaptic markers Homer1, Bassoon, PSD-95, Synaptophysin, the astrocytic protein GFAP, myelin basic protein (MBP), and anti-GFP antibodies in dissociated neuron cultures and mouse brain tissue sections. pan-ExM-t reveals these markers in the context of ultrastructural features such as pre and postsynaptic densities, 3D nanoarchitecture of neuropil, and the fine structures of cellular organelles. pan-ExM-t is adoptable in any neurobiological laboratory with access to a confocal microscope and has therefore broad applicability in the research community. Highlights pan-ExM-t visualizes proteins in the context of synaptic ultrastructure Lipid labeling in pan-ExM-t reveals organellar and cellular membranes All-optical, easily accessible alternative to correlative light/electron microscopy High potential for high throughput connectomics studies

13 citations


Journal ArticleDOI
TL;DR: In this article , the effects of silver nanoparticles on the midgut tissues of beetles (Blaps polychresta) collected from Egypt as a biological model were investigated.

13 citations


Journal ArticleDOI
TL;DR: In this article , the authors examined human airway epithelium infected with three different isolates of SARS-CoV-2 including the B.1.7 variant by transmission electron microscopy and tomography.
Abstract: Ultrastructural studies of SARS-CoV-2 infected cells are crucial to better understand the mechanisms of viral entry and budding within host cells. Here, we examined human airway epithelium infected with three different isolates of SARS-CoV-2 including the B.1.1.7 variant by transmission electron microscopy and tomography. For all isolates, the virus infected ciliated but not goblet epithelial cells. Key SARS-CoV-2 entry molecules, ACE2 and TMPRSS2, were found to be localised to the plasma membrane including microvilli but excluded from cilia. Consistently, extracellular virions were seen associated with microvilli and the apical plasma membrane but rarely with ciliary membranes. Profiles indicative of viral fusion where tomography showed that the viral membrane was continuous with the apical plasma membrane and the nucleocapsids diluted, compared with unfused virus, demonstrate that the plasma membrane is one site of entry where direct fusion releasing the nucleoprotein-encapsidated genome occurs. Intact intracellular virions were found within ciliated cells in compartments with a single membrane bearing S glycoprotein. Tomography showed concentration of nucleocapsids round the periphery of profiles strongly suggestive of viral budding into these compartments and this may explain how virions gain their S glycoprotein containing envelope.

13 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured changes in all distinguishable organelle numbers, sizes, and morphologies in over 2100 electron micrographs and revealed a major restructuring of the cell's internal architecture during the progressive heat shock.
Abstract: When the temperature is increased, the heat shock response is activated to protect the cellular environment. The transcriptomics and proteomics of this process are intensively studied, while information about how the cell responds structurally to heat stress is mostly lacking. Here, Saccharomyces cerevisiae were subjected to a mild continuous heat shock (38°C) and intermittently cryo-immobilized for electron microscopy. Through measuring changes in all distinguishable organelle numbers, sizes, and morphologies in over 2100 electron micrographs a major restructuring of the cell's internal architecture during the progressive heat shock was revealed. The cell grew larger but most organelles within it expanded even more, shrinking the volume of the cytoplasm. Organelles responded to heat shock at different times, both in terms of size and number, and adaptations of certain organelles' morphology (such as the vacuole), were observed. Multivesicular bodies grew to almost 170% in size, indicating a previously unknown involvement in the heat shock response. A previously undescribed electron translucent structure accumulated close to the plasma membrane. This all-encompassing approach provides a detailed chronological progression of organelle adaptation throughout the cellular heat-stress response.

12 citations


Journal ArticleDOI
TL;DR: In this paper , the adverse impacts of Ag-NPs on the ovaries of female beetles were investigated by estimating the enzyme activities, DNA damage using a comet assay, and apoptosis by means of flow cytometry.
Abstract: With the evolution of nanostructure materials, silver nanoparticles (Ag-NPs) emerged as the predominantly exploited nanomaterial in multifarious sectors due to their versatile properties. Along with the heightening applications of Ag-NPs, however, there is increasing concern over their indubitable toxicity towards the ecosystem, which indeed affects surrounding organisms and human health. In this study, we evaluated the detrimental effects of Ag-NPs in relation to Egyptian wild female beetles, Blaps polychresta, after injection with a single dose of Ag-NPs at different doses and monitoring for 30 days to determine the sublethal dose. Accordingly, the sublethal dose revealed the lowest negative influence was found at 0.03 mg/g body weight. The adverse impacts of Ag-NPs on the ovaries of female beetles were investigated by estimating the enzyme activities, DNA damage using a comet assay, and apoptosis by means of flow cytometry. Besides, the ultrastructural abnormalities were surveyed adopting transmission electron microscopy (TEM). The results manifested comet cells of 7.67 ± 0.88% and 22.33 ± 0.51 for Ag-NPs treated and control groups, respectively. Similarly, the data from flow cytometry demonstrated a substantial reduction in viable cells associated with a significant rise in apoptotic cells for the Ag-NPs treated group in comparison with the control group. Moreover, significant disturbances in enzyme activities for the treated group were perceived correlated with evident diminutions in antioxidant enzymes. Remarkably, the ultrastructural investigation emphasized these findings, exposing considerable deformities of the ovaries in the Ag-NPs treated group compared with the control group. To the best of our knowledge, this is the first report discussing the influence of Ag-NPs at the lowest dose on ovaries of B. polychresta. Collectively, our findings would significantly contribute to considering the critical effects of Ag-NPs at low levels, in addition to the potential use of B. polychresta as a good bio-indicator in ecotoxicological analyses.

Journal ArticleDOI
TL;DR: In this article , the authors summarize the ultrastructural and biochemical features of pathogenic proteins extracted from the brains of patients with neurodegenerative diseases that accumulate abnormal forms of tau, α-synuclein, and TDP-43, and discuss how these disease-specific properties are maintained in the brain.
Abstract: Abstract Intracellular accumulation of abnormal proteins with conformational changes is the defining neuropathological feature of neurodegenerative diseases. The pathogenic proteins that accumulate in patients' brains adopt an amyloid-like fibrous structure and exhibit various ultrastructural features. The biochemical analysis of pathogenic proteins in sarkosyl-insoluble fractions extracted from patients’ brains also shows disease-specific features. Intriguingly, these ultrastructural and biochemical features are common within the same disease group. These differences among the pathogenic proteins extracted from patients’ brains have important implications for definitive diagnosis of the disease, and also suggest the existence of pathogenic protein strains that contribute to the heterogeneity of pathogenesis in neurodegenerative diseases. Recent experimental evidence has shown that prion-like propagation of these pathogenic proteins from host cells to recipient cells underlies the onset and progression of neurodegenerative diseases. The reproduction of the pathological features that characterize each disease in cellular and animal models of prion-like propagation also implies that the structural differences in the pathogenic proteins are inherited in a prion-like manner. In this review, we summarize the ultrastructural and biochemical features of pathogenic proteins extracted from the brains of patients with neurodegenerative diseases that accumulate abnormal forms of tau, α-synuclein, and TDP-43, and we discuss how these disease-specific properties are maintained in the brain, based on recent experimental insights.

Journal ArticleDOI
10 Mar 2022-Forests
TL;DR: In this paper , the authors describe the current level of knowledge about chemical characteristics of the wood cell walls, including the distribution of main components in the cell walls of normal wood, reaction wood and water-logged archaeological wood, the cellulose microfibrils orientation, and the interactions between main components.
Abstract: Wood is complex in its chemical composition that has an important influence on its chemical behavior and mechanical strength. The complexity is reflected in the ultrastructure of the wood cell wall. In particular, the concentration of main components (cellulose, hemicelluloses and lignin) changes depending on many factors such as the different type or parts of wood, and varies in different cell wall layers. From an ultrastructural standpoint, we describe the current level of knowledge about chemical characteristics of the wood cell walls. The information of distribution of main components in the cell walls of normal wood, reaction wood and water-logged archaeological wood, the cellulose microfibrils orientation, and the interactions between main components were presented based on the use of advanced techniques including transmission electron microscopy, scanning electron microscopy, spectral imaging and nuclear magnetic resonance. In addition, the chemical changes of the wood cell wall during pretreatment are discussed. This mini-review not only provides a better understanding of wood chemistry, but also brings new insights into cell wall recalcitrance.

Posted ContentDOI
24 Jan 2022-bioRxiv
TL;DR: In this paper , a suite of ultrastructural quantifications, integrated into a single pipeline called the surface morphometrics toolkit, is presented, allowing detailed mapping of spacing, curvature, and orientation onto reconstructed membrane meshes, highlighting subtle organellar features that are challenging to detect in 3D.
Abstract: Cellular cryo-electron tomography (cryo-ET) enables 3-dimensional reconstructions of organelles in their native cellular environment at subnanometer resolution. However, quantifying ultrastructural features of pleomorphic organelles in three dimensions is challenging, as is defining the significance of observed changes induced by specific cellular perturbations. To address this challenge, we established a semi-automated workflow to segment organellar membranes and reconstruct their underlying surface geometry in cryo-ET. To complement this workflow, we developed an open source suite of ultrastructural quantifications, integrated into a single pipeline called the surface morphometrics toolkit. This toolkit allows detailed mapping of spacing, curvature, and orientation onto reconstructed membrane meshes, highlighting subtle organellar features that are challenging to detect in three dimensions and allowing for statistical comparison across many organelles. To demonstrate the advantages of this approach, we combine cryo-ET with cryo-fluorescence microscopy to correlate bulk mitochondrial network morphology (i.e., elongated versus fragmented) with membrane ultrastructure of individual mitochondria in the presence and absence of endoplasmic reticulum (ER) stress. Using our toolkit, we demonstrate ER stress promotes adaptive remodeling of ultrastructural features of mitochondria including spacing between the inner and outer membranes, local curvature of the inner membrane, and spacing between mitochondrial cristae. We show that differences in membrane ultrastructure correlate to mitochondrial network morphologies, suggesting that these two remodeling events are coupled. Our toolkit offers opportunities for quantifying changes in organellar architecture on a single-cell level using cryo-ET, opening new opportunities to define changes in ultrastructural features induced by diverse types of cellular perturbations.

Journal ArticleDOI
08 Jul 2022-Science
TL;DR: Examining additional specimens in previously unexplored techniques found evidence that yunnanozoan branchial arches consist of cellular cartilage with an extracellular matrix dominated by microfibrils, a feature hitherto considered specific to vertebrates.
Abstract: Pharyngeal arches are a key innovation that likely contributed to the evolution of the jaws and braincase of vertebrates. It has long been hypothesized that the pharyngeal (branchial) arch evolved from an unjointed cartilaginous rod in vertebrate ancestors such as that in the nonvertebrate chordate amphioxus, but whether such ancestral anatomy existed remains unknown. The pharyngeal skeleton of controversial Cambrian animals called yunnanozoans may contain the oldest fossil evidence constraining the early evolution of the arches, yet its correlation with that of vertebrates is still disputed. By examining additional specimens in previously unexplored techniques (for example, x-ray microtomography, scanning and transmission electron microscopy, and energy dispersive spectrometry element mapping), we found evidence that yunnanozoan branchial arches consist of cellular cartilage with an extracellular matrix dominated by microfibrils, a feature hitherto considered specific to vertebrates. Our phylogenetic analysis provides further support that yunnanozoans are stem vertebrates. Description Vertebrate ancestor? Yunnanozoans are Cambrian animals with a taxonomic position that has long been debated with regard to whether they are ancestral chordates. Tian et al. use new imaging approaches on new yunnanozoan specimens and found evidence that their branchial arches are composed of cartilage within an extracellular matrix of micofibrils (see the Perspective by Miyashita). This combination of tissue types has been considered vertebrate specific, suggesting that this group of animals are indeed basal vertebrates. This relationship allows insight into the evolution of the pharyngeal skeleton (including the jaw and cranium) to be obtained from examination of this ancient progenitor. —SNV The Cambrian fossil yunnanozoans are stem vertebrates with diagnostic traits of vertebrate pharyngeal arches.

Journal ArticleDOI
TL;DR: In this paper , the ultrastructural and nanomechanical properties of arterial tissues are reported, and maps of aorta tissue stiffness in its three constitutive layers, namely tunica intima, media, and adventitia, are reported.
Abstract: Soft biological tissues are natural biomaterials with structures that have evolved to perform physiological functions, for example, conferring elasticity while preserving the mechanical integrity of arteries. Furthermore, the mechanical properties of the tissue extracellular matrix (ECM) significantly affect cell behavior and organ function. ECM mechanical properties are strongly affected by collagen ultrastructure, and perturbations in collagen networks can cause tissue mechanical failure. It is thus crucial to understand the ultrastructural mechanical properties of soft tissues. Herein, the ultrastructural and nanomechanical properties of arterial tissues are reported. Specifically, maps of aorta tissue stiffness in its three constitutive layers, namely tunica intima, media, and adventitia, are reported. Atomic force microscopy (AFM) with large and ultrasharp tips is used to explore tissue stiffness at two scales. Quasistatic tensile tests are further conducted to understand a potential correspondence between small-scale mechanical properties obtained via AFM indentation and macroscopic behavior of the tissue at low and large strains. Furthermore, gradients in stiffness across the various layers as well as deformation rate effects are investigated. It is envisioned that the established methodology serves as a tool to investigate the effect of ECM remodeling associated with vascular diseases such as aneurysms and arterial stiffening linked to hypertension.

Journal ArticleDOI
TL;DR: In this article , the impact of desiccation-induced genotoxic stress on nucleolar ultrastructure and ribogenesis was explored along the rehydration−dehydration cycle applied in standard seed vigorization protocols.
Abstract: Abstract Re‐establishment of desiccation tolerance is essential for the survival of germinated seeds facing water deficit in the soil. The molecular and ultrastructural features of desiccation tolerance maintenance and loss within the nuclear compartment are not fully resolved. In the present study, the impact of desiccation‐induced genotoxic stress on nucleolar ultrastructure and ribogenesis was explored along the rehydration−dehydration cycle applied in standard seed vigorization protocols. Primed and overprimed Medicago truncatula seeds, obtained through hydropriming followed by desiccation (dry‐back), were analysed. In contrast to desiccation‐tolerant primed seeds, overprimed seeds enter irreversible germination and do not survive dry‐back. Reactive oxygen species, DNA damage and expression profiles of antioxidant/DNA Damage Response genes were measured, as main hallmarks of the seed response to desiccation stress. Nuclear ultrastructural features were also investigated. Overprimed seeds subjected to dry‐back revealed altered rRNA accumulation profiles and up‐regulation of genes involved in ribogenesis control. The signal molecule PAP (3′‐phosphoadenosine 5′‐phosphate) accumulated during dry‐back only in primed seeds, as a distinctive feature of desiccation tolerance. The presented results show the molecular and ultrastructural landscapes of the seed desiccation response, including substantial changes in nuclear organization.

Journal ArticleDOI
TL;DR: In this paper , the authors used transmission electron microscopy (TEM) coupled with confocal laser scanning microscopy to analyze the pyrenoid and the chloroplast of 20 Trebouxia species-level lineages.
Abstract: Trebouxiophyceae is a wide class of green algae comprising coccoid and elliptic unicells, filaments, blades and colony-forming species that occur in diverse terrestrial and aquatic environments. Within this class, the genus Trebouxia Puymaly is among the most widespread lichen phycobionts worldwide. However, the 29 formally described species based on the combination of morphological traits and genetic diversity woefully underrepresented the overall species-level diversity recognized in the genus. In Trebouxia, reliable differentiation and characterization of the species-level lineages can be achieved by studying the diversity of key diagnostic features of pyrenoid ultrastructure and chloroplast morphology of axenically grown algal cultures. Here, we used transmission electron microscopy (TEM) coupled with confocal laser scanning microscopy (CLSM) to analyze the pyrenoid and the chloroplast of 20 Trebouxia species-level lineages grown directly on solid agar medium and on cellulose-acetate discs laid over the agar medium. With the new, detailed morphoanatomical characterization of these species-level lineages, we reappraise Trebouxia taxonomy in light of the most recent phylogenetic delimitation provided by Muggia et al. (2020).

Journal ArticleDOI
TL;DR: In this article , a quantitative density and ultrastructural analysis of dark microglia was performed using high-throughput scanning electron microscopy in the ventral hippocampus CA1 stratum lacunosum-moleculare of 20-month-old APP-PS1 vs C57BL/6J male mice.
Abstract: A diverse heterogeneity of microglial cells was previously described in Alzheimer's disease (AD) pathology, including dark microglia, a state characterized by ultrastructural markers of cellular stress. To provide novel insights into the roles of dark microglia during aging in the context of AD pathology, we performed a quantitative density and ultrastructural analysis of these cells using high-throughput scanning electron microscopy in the ventral hippocampus CA1 stratum lacunosum-moleculare of 20-month-old APP-PS1 vs C57BL/6J male mice. The density of dark microglia was significantly higher in APP-PS1 vs C57BL/6J mice, with these cells accounting for nearly half of all microglia observed near amyloid-beta (Aβ) plaques. This dark microglial state interacted more with dystrophic neurites compared to other APP-PS1 microglia and possessed glycogen granules, associated with a metabolic shift toward glycolysis, which provides the first ultrastructural evidence of their presence in microglia. Dark microglia were further observed in aging human post-mortem brain samples showing similar ultrastructural features as in mouse. Overall, our results provide a quantitative ultrastructural characterization of a microglial state associated with cellular stress (i.e., dark microglia) that is primarily restricted near Aβ plaques and dystrophic neurites. The presence of this microglial state in the aging human post-mortem brain is further revealed.

Journal ArticleDOI
TL;DR: This review updates the current knowledge about the embryonic origin, development modifications, spatial arrangement, ultrastructural characteristics, and protein profile of the lamellar cells of cutaneous end-organ complexes focusing on Meissner and Pacinian morphotypes.
Abstract: Sensory corpuscles, or cutaneous end-organ complexes, are complex structures localized at the periphery of Aβ-axon terminals from primary sensory neurons that primarily work as low-threshold mechanoreceptors. Structurally, they consist, in addition to the axons, of non-myelinating Schwann-like cells (terminal glial cells) and endoneurial- and perineurial-related cells. The terminal glial cells are the so-called lamellar cells in Meissner and Pacinian corpuscles. Lamellar cells are variably arranged in sensory corpuscles as a “coin stack” in the Meissner corpuscles or as an “onion bulb” in the Pacinian ones. Nevertheless, the origin and protein profile of the lamellar cells in both morphotypes of sensory corpuscles is quite similar, although it differs in the expression of mechano-gated ion channels as well as in the composition of the extracellular matrix between the cells. The lamellar cells have been regarded as supportive cells playing a passive role in the process of genesis of the action potential, i.e., the mechanotransduction process. However, they express ion channels related to the mechano–electric transduction and show a synapse-like mechanism that suggest neurotransmission at the genesis of the electrical action potential. This review updates the current knowledge about the embryonic origin, development modifications, spatial arrangement, ultrastructural characteristics, and protein profile of the lamellar cells of cutaneous end-organ complexes focusing on Meissner and Pacinian morphotypes.

Journal ArticleDOI
20 Apr 2022-Plants
TL;DR: This review gives an overview from sample preparation through to imaging and a detailed account of how Cryo-scanning electron microscopy has been applied across diverse areas of plant research.
Abstract: Many research questions require the study of plant morphology, in particular cells and tissues, as close to their native context as possible and without physical deformations from some preparatory chemical reagents or sample drying. Cryo-scanning electron microscopy (cryoSEM) involves rapid freezing and maintenance of the sample at an ultra-low temperature for detailed surface imaging by a scanning electron beam. The data are useful for exploring tissue/cell morphogenesis, plus an additional cryofracture/cryoplaning/milling step gives information on air and water spaces as well as subcellular ultrastructure. This review gives an overview from sample preparation through to imaging and a detailed account of how this has been applied across diverse areas of plant research. Future directions and improvements to the technique are discussed.

Book ChapterDOI
01 Jan 2022
TL;DR: In this paper , the authors describe methodologies to properly dissect BAT depots, evaluate their gross anatomy, and assess its activation by light microscopy using peroxidase immunostaining and by laser scanning confocal microscopy with immunofluorescence.
Abstract: The Brown Adipose Tissue (BAT) is composed by mitochondrial rich, multilocular adipocytes, in strict topographical and functional relation with vasculature and noradrenergic nerves. Brown adipocytes are able to dissipate energy to produce heat, in a process known as non-shivering thermogenesis. Due to its contribution to energy expenditure, BAT is intensely studied for its potential to counteract metabolic diseases such as obesity, type 2 diabetes, dyslipidemia and cardiovascular diseases. BAT displays specific morphological characteristics that allow to assess its functional state. In this chapter we describe methodologies to properly dissect BAT depots, evaluate their gross anatomy, and assess its activation by light microscopy using peroxidase immunostaining and by laser scanning confocal microscopy using immunofluorescence. We also describe methodologies to study BAT ultrastructure by transmission and scanning electron microscopy, to visualize peroxidase immunostaining reactions at an ultrastructural level and to perform immunofluorescence reactions on paraffin-embedded samples, more often available in the clinical setting (due to the possibility to store them long-term) as opposed to fresh samples. The described techniques can be employed to study BAT morphology and activation in response to various stimuli (e.g., cold exposure; specific dietary composition) and in different pathological conditions (e.g., obesity; type 2 diabetes).

Journal ArticleDOI
TL;DR: In this article , the impact of AgNPs solutions on cell ultrastructure was examined in pea ( Pisum sativum L) using a transmission electron microscope (TEM) and the effect of AgNs treatments on the α, β esterase (EST), and peroxidase (POX) enzymes expression as well as gain or loss of inter simple sequence repeat (ISSRs) markers has been described.

Journal ArticleDOI
TL;DR: A poor surface characteristic and elemental composition of the enamel surface of primary teeth is observed in diabetic children and appropriate caries preventive measures are mandatory to maintain the structural integrity of the tooth in these patients.
Abstract: Diabetes affects the developing enamel by altering the mineralization process, which can have a detrimental effect on oral health. The objectives of this study were to examine the ultrastructure and composition of surface enamel in primary teeth of diabetic children and its clinical implications. Hundred extracted primary teeth from diabetic children (Test group: n = 50) and healthy children (Control group: n = 50), between 6 and 12 years of age, were subjected to scanning electron microscopy to qualitatively examine the enamel surface. Energy dispersive X-ray (EDX) analysis was performed to investigate the mass percentage of calcium (Ca) and phosphorous (P) in the surface enamel. Ultrastructural aberrations of surface enamel were observed in the test group teeth. Additionally, prism perforations were seen at the junction of rod and inter-rod enamel and the prisms were loosely packed. An even aprismatic layer of surface enamel was evident in the control group teeth. There was a statistically significant difference (p < 0.05) of Ca and P mass percentage between the test and control group teeth. The mean mass percentage rates of Ca and P were 33.75% and 16.76%, respectively. A poor surface characteristic and elemental composition of the enamel surface of primary teeth is observed in diabetic children. Therefore, appropriate caries preventive measures are mandatory to maintain the structural integrity of the tooth in these patients.

Journal ArticleDOI
TL;DR: TissUExM as discussed by the authors is a method to expand millimeter-scale and mechanically heterogeneous whole embryonic tissues, including Drosophila wing discs, whole zebrafish, and mouse embryos.
Abstract: Super-resolution microscopy reveals the molecular organization of biological structures down to the nanoscale. While it allows the study of protein complexes in single cells, small organisms, or thin tissue sections, there is currently no versatile approach for ultrastructural analysis compatible with whole vertebrate embryos. Here, we present tissue ultrastructure expansion microscopy (TissUExM), a method to expand millimeter-scale and mechanically heterogeneous whole embryonic tissues, including Drosophila wing discs, whole zebrafish, and mouse embryos. TissUExM is designed for the observation of endogenous proteins. It permits quantitative characterization of protein complexes in various organelles at super-resolution in a range of ∼3 mm-sized tissues using conventional microscopes. We demonstrate its strength by investigating tissue-specific ciliary architecture heterogeneity and ultrastructural defects observed upon ciliary protein overexpression. Overall, TissUExM is ideal for performing ultrastructural studies and molecular mapping in situ in whole embryos.

Journal ArticleDOI
TL;DR: In this paper , the arrangement of collagen fibrils and proteoglycans (PGs) within the mechanically loaded aortic wall was investigated using convolutional neural networks.

Journal ArticleDOI
01 Feb 2022-Cells
TL;DR: The cell wall plays a crucial role in plant growth and development, including in response to environmental factors, mainly through significant biochemical and biomechanical plasticity as discussed by the authors , and the involvement of the cell wall in C4 plants' response to cold is, however, still poorly understood.
Abstract: The cell wall plays a crucial role in plant growth and development, including in response to environmental factors, mainly through significant biochemical and biomechanical plasticity. The involvement of the cell wall in C4 plants’ response to cold is, however, still poorly understood. Miscanthus × giganteus, a perennial grass, is generally considered cold tolerant and, in contrast to other thermophilic species such as maize or sorgo, can maintain a relatively high level of photosynthesis efficiency at low ambient temperatures. This unusual response to chilling among C4 plants makes Miscanthus an interesting study object in cold acclimation mechanism research. Using the results obtained from employing a diverse range of techniques, including analysis of plasmodesmata ultrastructure by means of transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and biomechanical tests coupled with photosynthetic parameters measurements, we present evidence for the implication of the cell wall in genotype-specific responses to cold in this species. The observed reduction in the assimilation rate and disturbance of chlorophyll fluorescence parameters in the susceptible M3 genotype under cold conditions were associated with changes in the ultrastructure of the plasmodesmata, i.e., a constriction of the cytoplasmic sleeve in the central region of the microchannel at the mesophyll–bundle sheath interface. Moreover, this cold susceptible genotype was characterized by enhanced tensile stiffness, strength of leaf wall material, and a less altered biochemical profile of the cell wall, revealed by FTIR spectroscopy, compared to cold tolerant genotypes. These changes indicate that a decline in photosynthetic activity may result from a decrease in leaf CO2 conductance due to the formation of more compact and thicker cell walls and that an enhanced tolerance to cold requires biochemical wall remodelling. Thus, the well-established trade-off between photosynthetic capacity and leaf biomechanics found across multiple species in ecological research may also be a relevant factor in Miscanthus’ tolerance to cold. In this paper, we demonstrate that M. giganteus genotypes showing a high degree of genetic similarity may respond differently to cold stress if exposed at earlier growing seasons to various temperature regimes, which has implications for the cell wall modifications patterns.

Journal ArticleDOI
TL;DR: In this article , the concentrations of Na, Cl, K, Ca, Mg, P and S in various cell types within the leaf blades of a monocotyledonous C4 halophyte, Rhodes grass (Chloris gayana).
Abstract: Abstract Halophytes accumulate and sequester high concentrations of salt in vacuoles while maintaining lower levels of salt in the cytoplasm. The current data on cellular and subcellular partitioning of salt in halophytes are, however, limited to only a few dicotyledonous C3 species. Using cryo‐scanning electron microscopy X‐ray microanalysis, we assessed the concentrations of Na, Cl, K, Ca, Mg, P and S in various cell types within the leaf‐blades of a monocotyledonous C4 halophyte, Rhodes grass (Chloris gayana). We also linked, for the first time, elemental concentrations in chloroplasts of mesophyll and bundle sheath cells to their ultrastructure and photosynthetic performance of plants grown in nonsaline and saline (200 mM NaCl) conditions. Na and Cl accumulated to the highest levels in xylem parenchyma and epidermal cells, but were maintained at lower concentrations in photosynthetically active mesophyll and bundle sheath cells. Concentrations of Na and Cl in chloroplasts of mesophyll and bundle sheath cells were lower than in their respective vacuoles. No ultrastructural changes were observed in either mesophyll or bundle sheath chloroplasts, and photosynthetic activity was maintained in saline conditions. Salinity tolerance in Rhodes grass is related to specific cellular Na and Cl distributions in leaf tissues, and the ability to regulate Na and Cl concentrations in chloroplasts.

Journal ArticleDOI
TL;DR: In this article , the nanostructure of modern and ancient nettle samples was studied using wide-angle X-ray scattering (WAXS) and compared to other bast fibres.
Abstract: Abstract Stinging nettle ( Urtica dioica ) is a potential source material for industrial applications. However, systematic research on the ultrastructural properties of nettle fibres is lacking. Determining the ultrastructure of nettle and the other bast fibres also provides new insights into the studies of archaeological fibres and their usage. In this study, the nanostructure of modern and ancient nettle samples was studied using wide-angle X-ray scattering (WAXS) and compared to other bast fibres. The culturo-historical fibre samples consisted of nettle, flax, and hemp from White Karelian textiles collected 1894 as well as of 800–900-year-old archaeological textile fragments from Ravattula Ristimäki burial site, Finland. Using WAXS, the average cellulose crystallite widths, relative crystallinities and orientational order (including microfibril angle for the modern fibres) were determined and compared. The results also revealed the suitability of the WAXS analysis for fibre identification. The crystallite widths were of the similar size for all modern fibres (3.4–4.8 nm). Subtle differences in the relative crystallinities in descending order (from flax to nettle, and finally hemp) were observed. Also, subtle differences in the mean MFAs were observed (10 ± 1° for flax, 12 ± 1° for nettle, and 14 ± 1° for hemp). For the culturo-historical fibres, the values for crystallite widths and relative crystallinities were larger compared to the corresponding modern references. In addition, features due to the presence of non-cellulosic, crystalline substances (e.g., calcium oxalates) were detected in the WAXS patterns of all the modern nettle fibres. These features could potentially be used as a tool for identification purposes. Graphical abstract

Journal ArticleDOI
01 May 2022-Heliyon
TL;DR: In this paper , the ultrastructural features of the choroidal scleral transition zone were investigated by comparing avian, non-human primate and human eyes, with the goal to confirm whether specific mechanical structures are present.