Showing papers on "Ultrastructure published in 2021"
TL;DR: Using micrographs from infected cell cultures and autopsy tissues, it is shown how coronavirus replication affects ultrastructure and put the morphological findings in the context of viral replication, which induces extensive remodelling of the intracellular membrane systems.
Abstract: Transmission electron microscopy has become a valuable tool to investigate tissues of COVID-19 patients because it allows visualisation of SARS-CoV-2, but the "virus-like particles" described in several organs have been highly contested. Because most electron microscopists in pathology are not accustomed to analysing viral particles and subcellular structures, our review aims to discuss the ultrastructural changes associated with SARS-CoV-2 infection and COVID-19 with respect to pathology, virology, and electron microscopy. Using micrographs from infected cell cultures and autopsy tissues, we show how coronavirus replication affects ultrastructure and put the morphological findings in the context of viral replication, which induces extensive remodelling of the intracellular membrane systems. Virions assemble by budding into the endoplasmic reticulum-Golgi intermediate complex and are characterized by electron dense dots of cross-sections of the nucleocapsid inside the viral particles. Physiological mimickers such as multivesicular bodies or coated vesicles serve as perfect decoys. Compared to other in-situ techniques, transmission electron microscopy is the only method to visualize assembled virions in tissues and will be required to prove SARS-CoV-2 replication outside the respiratory tract. In practice, documenting in tissues the characteristic features seen in infected cell cultures, seems to be much more difficult than anticipated. In our view, the hunt for coronavirus by transmission electron microscopy is still on.
72 citations
TL;DR: The step-by-step U-ExM protocol is described, which steps may be modified in order to optimize the expansion and preservation of the structure of interest and it is demonstrated that the cell ultrastructure can be preserved after expansion and thus reveals details that were previously only accessible by transmission electron microscopy.
Abstract: Expansion microscopy (ExM) physically magnifies specimens, allowing to obtain super-resolution images using a conventional diffraction-limited microscope such as confocal microscopy. By optimizing several steps of this method, we demonstrated that the cell ultrastructure can be preserved after expansion and thus reveals details that were previously only accessible by transmission electron microscopy. As a result, we called this method ultrastructure expansion microscopy (U-ExM). Here we describe the step-by-step U-ExM protocol, as well as pitfalls and how to avoid them. We explain which steps may be modified in order to optimize the expansion and preservation of the structure of interest. Finally, we are demonstrating that U-ExM can be successfully applied to isolated macromolecular structures, unicellular organisms and human cells in culture.
53 citations
TL;DR: In this paper, the authors used TEM to perform kinetic analysis of the ultrastructure of SARS-CoV-2 infected cells and found that early infection events were characterized by the presence of clusters of single-membrane vesicles and stacks of membrane containing nuclear pores called annulate lamellae.
Abstract: Many studies on SARS-CoV-2 have been performed over short-time scale, but few have focused on the ultrastructural characteristics of infected cells. We used TEM to perform kinetic analysis of the ultrastructure of SARS-CoV-2-infected cells. Early infection events were characterized by the presence of clusters of single-membrane vesicles and stacks of membrane containing nuclear pores called annulate lamellae (AL). A large network of host cell-derived organelles transformed into virus factories was subsequently observed in the cells. As previously described for other RNA viruses, these replication factories consisted of double-membrane vesicles (DMVs) located close to the nucleus. Viruses released at the cell surface by exocytosis harbored the typical crown of spike proteins, but viral particles without spikes were also observed in intracellular compartments, possibly reflecting incorrect assembly or a cell degradation process.
47 citations
TL;DR: The recently developed ultrastructure expansion microscopy (U-ExM) technique allows increasing the spatial resolution within a cell or tissue for microscopic imaging through the physical expanses.
Abstract: The recently developed ultrastructure expansion microscopy (U-ExM) technique allows us to increase the spatial resolution within a cell or tissue for microscopic imaging through the physical expans...
12 citations
TL;DR: In this paper, the authors validate the use of U-ExM in trypanosoma brucei by visualizing the nucleus and kDNA as well as proteins of the cytoskeleton, the basal body, the mitochondrion and the ER.
Abstract: -Introduction The recently developed ultrastructure expansion microscopy (U-ExM) technique allows to increase the spatial resolution within a cell or tissue for microscopic imaging through the physical expansion of the sample. In this study we validate the use of U-ExM in Trypanosoma brucei by visualizing the nucleus and kDNA as well as proteins of the cytoskeleton, the basal body, the mitochondrion and the ER. T. brucei is a unicellular flagellated protozoan parasite and the causative agent of human African sleeping sickness and Nagana in cattle.The highly polarized parasite cell body is about 25 μm in length and is shaped by the subpellicular microtubule corset. Its single flagellum emanates from the posterior part of the cell and is attached along the entire cell body. T. brucei The cell contains all typical organelles of eukaryotic cells including ER, Golgi and mitochondrion. Interestingly, Golgi and mitochondrion are single unit organelles in this protozoan parasite. The signature feature of trypanosomes is the single unit mitochondrial genome, the kinetoplast DNA (kDNA) that is organized in a complex structure of interlocked mini- and maxicircles. The kDNA is segregated during cell division by the tripartite attachment complex (TAC) that connects it via the mitochondrial membranes to the base of the flagellum.
11 citations
TL;DR: In this article, a correlative light electron microscopy (CLEM) approach was developed to study the graft interface with high ultrastructural resolution, and the formation of secondary plasmodesmata (PD) between the grafted partners was investigated.
Abstract: Despite recent progress in our understanding of graft union formation, we still know little about the cellular events underlying the grafting process. This is partially due to the difficulty of reliably targeting the graft interface in electron microscopy to study its ultrastructure and three-dimensional architecture. To overcome this technological bottleneck, we developed a correlative light electron microscopy (CLEM) approach to study the graft interface with high ultrastructural resolution. Grafting hypocotyls of Arabidopsis thaliana lines expressing YFP or mRFP in the endoplasmic reticulum allowed efficient targeting of the grafting interface for examination under light and electron microscopy. To explore the potential of our method to study sub-cellular events at the graft interface, we focused on the formation of secondary plasmodesmata (PD) between the grafted partners. We showed that 4 classes of PD were formed at the interface and that PD introgression into the cell wall was initiated equally by both partners. Moreover, the success of PD formation appeared not systematic with a third of PD not spanning the cell wall entirely. Characterizing the ultrastructural characteristics of these incomplete PD gives us insights into the process of secondary PD biogenesis. We found that the establishment of successful symplastic connections between the scion and rootstock occurred predominantly in the presence of thin cell walls and endoplasmic reticulum-plasma membrane tethering. The resolution reached in this work shows that our CLEM method advances the study of biological processes requiring the combination of light and electron microscopy.
10 citations
TL;DR: In this article, the authors used high-pressure frozen integuments to assess whether pigment organelles of crabs belong to the lysosome-related organelle (LRO) family and how their catabolism is intracellularly processed.
Abstract: Pigment organelles of vertebrates belong to the lysosome-related organelle (LRO) family, of which melanin-producing melanosomes are the prototypes. While their anabolism has been extensively unraveled through the study of melanosomes in skin melanocytes, their catabolism remains poorly known. Here, we tap into the unique ability of crab spiders to reversibly change body coloration to examine the catabolism of their pigment organelles. By combining ultrastructural and metal analyses on high-pressure frozen integuments, we first assess whether pigment organelles of crab spiders belong to the LRO family and, second, how their catabolism is intracellularly processed. Using scanning-transmission electron microscopy, electron tomography and nanoscale Synchrotron-based scanning X-ray fluorescence, we show that pigment organelles possess ultrastructural and chemical hallmarks of LROs, including intraluminal vesicles and metal deposits, similar to melanosomes. Monitoring ultrastructural changes during bleaching suggests that the catabolism of pigment organelles involves the degradation and removal of their intraluminal content, possibly through lysosomal mechanisms. In contrast to skin melanosomes, anabolism and catabolism of pigments proceed within the same cell without requiring either cell death or secretion/phagocytosis. Our work hence provides support for the hypothesis that the endolysosomal system is fully functionalized for within-cell turnover of pigments, leading to functional maintenance under adverse conditions and phenotypic plasticity. First formulated for eye melanosomes in the context of human vision, the hypothesis of intracellular turnover of pigments gets unprecedented strong support from pigment organelles of spiders.
9 citations
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).
9 citations
TL;DR: In this paper, the authors used high-pressure frozen integuments to assess whether pigment organelles of crab spiders belong to the lysosome-related organelle (LRO) family and how their catabolism is intracellularly processed.
Abstract: Pigment organelles of vertebrates belong to the lysosome-related organelle (LRO) family, of which melanin-producing melanosomes are the prototypes. While their anabolism has been extensively unraveled through the study of melanosomes in skin melanocytes, their catabolism remains poorly known. Here, we tap into the unique ability of crab spiders to reversibly change body coloration to examine the catabolism of their pigment organelles. By combining ultrastructural and metal analyses on high-pressure frozen integuments, we first assess whether pigment organelles of crab spiders belong to the LRO family and second, how their catabolism is intracellularly processed. Using scanning transmission electron microscopy, electron tomography, and nanoscale Synchrotron-based scanning X-ray fluorescence, we show that pigment organelles possess ultrastructural and chemical hallmarks of LROs, including intraluminal vesicles and metal deposits, similar to melanosomes. Monitoring ultrastructural changes during bleaching suggests that the catabolism of pigment organelles involves the degradation and removal of their intraluminal content, possibly through lysosomal mechanisms. In contrast to skin melanosomes, anabolism and catabolism of pigments proceed within the same cell without requiring either cell death or secretion/phagocytosis. Our work hence provides support for the hypothesis that the endolysosomal system is fully functionalized for within-cell turnover of pigments, leading to functional maintenance under adverse conditions and phenotypic plasticity. First formulated for eye melanosomes in the context of human vision, the hypothesis of intracellular turnover of pigments gets unprecedented strong support from pigment organelles of spiders.
8 citations
TL;DR: In this article, the authors offered animal proteins in the form of fluorescent albumin (FITC-BSA) and observed the reactions of the glands by live cell imaging and fluorescence microscopy, and the ultrastructure of these highly dynamic processes was also assessed in high pressure frozen and freeze substituted (HPF-FS) cells.
Abstract: Glands of Drosera absorb and transport nutrients from captured prey, but the mechanism and dynamics remain unclear. In this study, we offered animal proteins in the form of fluorescent albumin (FITC-BSA) and observed the reactions of the glands by live cell imaging and fluorescence microscopy. The ultrastructure of these highly dynamic processes was also assessed in high-pressure frozen and freeze substituted (HPF-FS) cells. HPF-FS yielded excellent preservation of the cytoplasm of all cell types, although the cytosol looked different in gland cells as compared to endodermoid and stalk cells. Especially prominent were the ER and its contacts with the plasma membrane, plasmodesmata, and other organelles as well as continuities between organelles. Also distinct were actin microfilaments in association with ER and organelles. Application of FITC-BSA to glands caused the formation of fluorescent endosomes that pinched off the plasma membrane. Endosomes fused to larger aggregates, and accumulated in the bulk cytoplasm around the nucleus. They did not fuse with the cell sap vacuole but remained for at least three days; in addition, fluorescent vesicles also proceeded through endodermoid and transfer cells to the epidermal and parenchymal cells of the tentacle stalk.
8 citations
TL;DR: Two strains of Sphaerodinium were established from two mountain areas in Portugal and examined by light microscopy, scanning and transmission electron microscopy and sequence analyses of nuclear-encoded SSU, ITS1-58S-S-ITS2 and LSU rDNA as discussed by the authors.
TL;DR: In this article, a specific point mutation, c.974-1G>A in WD Repeat Domain 45 (WDR45), was reported, showing iron accumulation in the brain, and autophagy defects in the fibroblasts.
Abstract: Iron overload in the brain, defined as excess stores of iron, is known to be associated with neurological disorders. In neurodegeneration accompanied by brain iron accumulation, we reported a specific point mutation, c.974-1G>A in WD Repeat Domain 45 (WDR45), showing iron accumulation in the brain, and autophagy defects in the fibroblasts. In this study, we investigated whether fibroblasts with mutated WDR45 accumulated iron, and other effects on cellular organelles. We first identified the main location of iron accumulation in the mutant fibroblasts and then investigated the effects of this accumulation on cellular organelles, including lipid droplets, mitochondria and lysosomes. Ultrastructure analysis using transmission electron microscopy (TEM) and confocal microscopy showed structural changes in the organelles. Increased numbers of lipid droplets, fragmented mitochondria and increased numbers of lysosomal vesicles with functional disorder due to WDR45 deficiency were observed. Based on correlative light and electron microscopy (CLEM) findings, most of the iron accumulation was noted in the lysosomal vesicles. These changes were associated with defects in autophagy and defective protein and organelle turnover. Gene expression profiling analysis also showed remarkable changes in lipid metabolism, mitochondrial function, and autophagy-related genes. These data suggested that functional and structural changes resulted in impaired lipid metabolism, mitochondrial disorder, and unbalanced autophagy fluxes, caused by iron overload.
TL;DR: In this article, a detailed description of histological and ultrafine structure of epidermis, upper parts of the digestive glands and the cnidosac, its innervation and proliferation using standard histological techniques, confocal laser scanning microscopy (CLSM) and transmission electron microscopy.
Abstract: Nudibranch mollusks (Gastropoda: Heterobranchia) are widely known for their ability to incorporate some active biochemical compounds of their prey, or even organelles and symbionts of the prey, which assured biological success of this group. At the same time, the process of nematocysts obtaining and incorporation into specific structures called cnidosacs by cladobranch mollusks remain poorly studied. This highlights a necessity of additional ultrastructural studies of cnidosac and adjacent organs in various aeolid mollusks using modern microscopic methods as they may provide new insight into the cnidosac diversity and fine-scale dynamics of nematocysts sequestration process. The present study is focused on the general and fine structure of the cnidosac area in cladobranch Aeolidia papillosa (Aeolidiidae). Specific goals of our study were to provide a detailed description of histological and ultrafine structure of epidermis, upper parts of the digestive glands and the cnidosac, its innervation and proliferation using standard histological techniques, confocal laser scanning microscopy (CLSM) and transmission electron microscopy. Our results clearly demonstrated that A. papillosa cnidosac is a much more complex structure, than it was thought, especially compared with simple cnidosacs found in flabellinids and facelinids. Using CLSM for functional morphological analysis provides a better resolution in visualization of structural elements within a cnidosac compared with traditional histological techniques. We revealed the presence of two cell types in the cnidophage zone: cnidophages and interstitial cells, which differ in ultrastructure and function. Our results also document the presence of a specific cnidopore zone, lined with differentiated cuboid epithelium bearing long microvilli, which likely provides a unidirectional flow of nematocysts during kleptocnides extrusion. For the first time, occurrence of vacuoles containing protective chitinous spindles in the cnidosac epithelium was shown.
TL;DR: The studies revealed that the ultrastructure of all cells which form the midgut epithelium in millipedes is general for all the species studied up to now and it resembles the cell ultrast structure observed in Chilopoda and Hexapoda, including the digestive, secretory and stem cells.
Abstract:
Abstract
The middle region of the digestive system of millipedes, the midgut, is responsible for all processes connected with digestion, but also takes part in homeostasis maintenance thanks to the ability to activate many mechanisms which neutralize changes occurring at different levels of the animal’s body. Numerous millipede species are treated as bioindicators of the natural environment and they are exposed to different stressors which originate from external environment. To obtain all data on the functioning of midgut of millipedes as the barrier against stressors, it is necessary to have a precise and general description of the midgut epithelium. Members from four millipede orders were selected for the studies: Polydesmus angustus (Polydesmida), Epibolus pulchripes (Spirobolida), Unciger transsilvanicus (Julida) and Glomeris tetrasticha (Glomerida). The structure and ultrastructure of their midgut epithelial cells (the digestive, secretory and regenerative cells) were documented using transmission electron microscopy and histochemical methods. The obtained results have been compared and discussed to previous ones, to present the general and structural organization of the midgut in Diplopoda. Our studies revealed that the ultrastructure of all cells which form the midgut epithelium in millipedes is general for all the species studied up to now and it resembles the cell ultrastructure observed in Chilopoda and Hexapoda, including the digestive, secretory and stem cells.
TL;DR: Herbs are processed by drying to decrease the moisture content and therefore to inhibit the growth of microorganisms, reducing the alterations during the storage and creating shelf-stable products as mentioned in this paper,...
Abstract: Herbs are processed by drying to decrease the moisture content and therefore to inhibit the growth of microorganisms, reducing the alterations during the storage and creating shelf-stable products....
TL;DR: Step-by-step protocols cover different approaches for sample preparation of almost any specimen, tools to identify and characterize classes or subpopulations of lysosomes and related organelles, and convenient, straightforward ways for manual, thus, non-automated measurements of globular or spheroid-shaped organlles.
Abstract: Changes in size and abundance of late endocytic and autophagic organelles are increasingly appreciated as highly indicative of the physiological or pathological conditions of cells. Electron microscopy (EM) is unsurpassed in high-resolution imaging of both ultrastructural and immunocytochemical features of subcellular compartments. EM-based morphometry permits precise quantitative analyses of organelles, especially after state-of-the-art cryopreparation. Here described step-by-step protocols cover (i) different approaches for sample preparation of almost any specimen, (ii) tools to identify and characterize classes or subpopulations of lysosomes and related organelles, and (iii) convenient, straightforward ways for manual, thus, non-automated measurements of globular or spheroid-shaped organelles.
TL;DR: In this article, a method combining light and electron microscopy with immunolabeling based on Tokuyasu's method was developed to overcome technical barriers, such as the loss of ultrastructural integrity, the decrease in antigenicity, or artifacts in the handling process, hinder the widespread use of the technique by biomedical researchers.
Abstract: Immuno-electron microscopy (Immuno-EM) is a powerful tool for identifying molecular targets with ultrastructural details in biological specimens. However, technical barriers, such as the loss of ultrastructural integrity, the decrease in antigenicity, or artifacts in the handling process, hinder the widespread use of the technique by biomedical researchers. We developed a method to overcome such challenges by combining light and electron microscopy with immunolabeling based on Tokuyasu's method. Using cryo-sectioned biological specimens, target proteins with excellent antigenicity were first immunolabeled for confocal analysis, and then the same tissue sections were further processed for electron microscopy, which provided a well-preserved ultrastructure comparable to that obtained using conventional electron microscopy. Moreover, this method does not require specifically designed correlative light and electron microscopy (CLEM) devices but rather employs conventional confocal and electron microscopes; therefore, it can be easily applied in many biomedical studies.
TL;DR: In this article, the authors analyzed the structure of the skin of the upper lip region of silver carp fishes using light, scanning, and transmission electron microscopy, and found that the skin was composed of epidermis, dermis, and hypodermis.
Abstract: This study was carried out to analyze the architecture of the skin of the upper lip region in silver carp fishes using light, scanning, and transmission electron microscopies. The skin was composed of epidermis, dermis, and hypodermis. The epidermis of the upper lip was characterized by the presence of large number of metachromatic mucous goblet cells, which showed positive reaction with Periodic Acid-Schiff (PAS), Alcian blue (AB), and toluidine blue. The electroreceptive lateral line system was organized into ampullary and tuberous organs. The scanning electron microscopy showed that the surface of the skin of upper lip was covered by microridges and characterized by the presence of taste buds and openings of lateral line system. As observed by transmission electron microscopy, the cytoplasm of the epidermal layers appeared electron-dense except for the superficial layer, where the cytoplasm was electron-lucent and contained many vacuoles and few profiles of rER. Moreover, the epidermis contained rodlet cells and stem cells. Few organelles were found within the cytoplasm of club cells. Neutrophils and eosinophilic granular cells were also demonstrated as important immune cells in the epidermis of the upper lip. Furthermore, lymphocytes and basophils could be identified with macrophage in the epidermal layer of the upper lip. Numerous telocytes were demonstrated between the collagen fibers of the dermis and bundles of myelinated nerve fibers. In conclusion, the skin of the upper lip region of silver carp displayed many sensory and immunological characteristic features.
TL;DR: In this article, the ultrastructural features of the lacrimal glands of patients with severe dry eye due to Stevens-Johnson syndrome (SJS) were examined using transmission electron microscopy (TEM).
Abstract: Purpose This study aimed to examine the ultrastructural features of the lacrimal glands of patients with severe dry eye due to Stevens-Johnson syndrome (SJS). Methods Biopsies form orbital lobes of six lacrimal glands obtained from fresh body donors (n=3) and patients with SJS (n=3; absolute tear deficiency; 2-6 months of disease duration) were examined using transmission electron microscopy (TEM). Results On TEM, normal lacrimal glandular tissue shows columnar acinar epithelial cells containing basally located rounded or oval euchromatic nuclei with cytoplasmic electron dense and moderately electron-dense secretory granules. Histologically, the lacrimal gland biopsies showed varied degree of acinar atrophy with lymphocytic infiltration in SJS patients. While on TEM, the lacrimal glands in SJS patients showed homogenous appearance of the nuclear chromatin of acinar cells with no differentiation into hetero-or euchromatin and loss of nucleoli. The cytoplasm lacked any electron dense material and showed significant loss of endoplasmic reticulum, mitochondria and Golgi bodies. The myoepithelial cells shared similar characteristics as in acinar epithelial cells along with loss of spindle shaped processes. Conclusion Transmission electron microscopy revealed ultrastructural changes in terms of nuclear composition, secretory vesicles, lysosomal vacuolation and myoepithelial cell distribution in the lacrimal glands of SJS patients.
TL;DR: It is concluded that different processes were triggered in the intestine and hepatopancreas to regenerate cells after damage, and mitochondria were the first organelles to respond to the appearance of a stressor in the living environment.
TL;DR: This study describes in detail the internal ultrastructure of hollow hooks, evidencing the presence of cytoplasm, mitochondria and fibrils, and considers that gland location and shape, composition of tentacular wall layers, and hook internal structure may serve as useful characters for the taxonomy and phylogeny of Trypanorhyncha.
Abstract: The scolex ultrastructure was studied in Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha) using histochemistry and transmission electron microscopy. We show for the first time the presence of scolex glands arranged in two longitudinal acini at the pars vaginalis parenchyma. These glands, along with those scattered in bothrial parenchyma, produce potentially adhesive glycoprotein secretions that are discharged via ducts to the bothrial grooves and apex. A particular type of sensory receptor was found around frontal gland pores, with a possible function in regulating their secretion activity. The internal structure of microtriches varies according to their morphotype and distribution on the scolex, this study providing the first description of the ultrastructure of serrate lanceolate spinitriches. The projections that form serrate margins are an extension of the medulla, differing from similar projections of other spinitriches. The large caps observed in serrate lanceolate spinitriches may reflect their specialization in attachment to and abrasion of intestinal mucosa, while the short caps and large bases of acicular filitriches may reflect their involvement in nutrient absorption. We also describe the rhyncheal apparatus ultrastructure, showing a similar basic structure of tentacular walls than that of other trypanorhynchs. Some differences among species in the number of fibrous layers, composition of the apical cytoplasm and presence of microvilli-like projections were discussed. Finally, our study describes in detail the internal ultrastructure of hollow hooks, evidencing the presence of cytoplasm, mitochondria and fibrils. The location of these fibrils may increase the area of contact surface of hooks on tentacles, possibly allowing for a higher tensile strength than that of solid hooks. We consider that gland location and shape, composition of tentacular wall layers, and hook internal structure may serve as useful characters for the taxonomy and phylogeny of Trypanorhyncha. RESEARCH HIGHLIGHTS: This is the first description of scolex internal ultrastructure in Grillotia carvajalregorum, showing the presence of glands arranged in two longitudinal acini at the pars vaginalis parenchyma, with potentially adhesive functions. The internal ultrastructure of serrate lanceolate spinitriches and acicular filitriches may reflect their specialization in attachment to the host intestinal mucosa and their involvement in nutrient absorption, respectively. Internally, hollow hooks have cytoplasm with mitochondria and fibrils, which are more widely distributed than in solid hooks, possibly increasing their tensile strength.
TL;DR: The present study clearly proves the connection of plate bodies with the rough endoplasmic reticulum and the presence of a vesicular network as part of the organelle involved in SP-A trafficking.
Abstract: Plate bodies are facultative organelles occasionally described in the adult lungs of various species, including sheep and goat. They consist of multiple layers of plate-like cisterns with an electron dense middle bar. The present study was performed to elucidate the three-dimensional (3D) characteristics of this organelle and its presumed function in surfactant protein A (SP-A) biology. Archived material of four adult goat lungs and PFA-fixed lung samples of two adult sheep lungs were used for the morphological and immunocytochemical parts of this study, respectively. 3D imaging was performed by electron tomography and focused ion beam scanning electron microscopy (FIB-SEM). Immuno gold labeling was used to analyze whether plate bodies are positive for SP-A. Transmission electron microscopy revealed the presence of plate bodies in three of four goat lungs and in both sheep lungs. Electron tomography and FIB-SEM characterized the plate bodies as layers of two up to over ten layers of membranous cisterns with the characteristic electron dense middle bar. The membranes of the plates were in connection with the rough endoplasmic reticulum and showed vesicular inclusions in the middle of the plates and a vesicular network at the sides of the organelle. Immuno gold labeling revealed the presence of SP-A in the vesicular network of plate bodies but not in the characteristic plates themselves. In conclusion, the present study clearly proves the connection of plate bodies with the rough endoplasmic reticulum and the presence of a vesicular network as part of the organelle involved in SP-A trafficking.
TL;DR: In this paper, the authors constructed several mutants by genetic manipulation to increase or decrease coiled-coil regions of HMW2, a major component protein of 200 kDa aligned in parallel along the cell axis.
Abstract: Length control is a fundamental requirement for molecular architecture. Even small wall-less bacteria have specially developed macro-molecular structures to support their survival. Mycoplasma pneumoniae, a human pathogen, forms a polar extension called an attachment organelle, which mediates cell division, cytadherence, and cell movement at host cell surface. This characteristic ultrastructure has a constant size of 250-300 nm, but its design principle remains unclear. In this study, we constructed several mutants by genetic manipulation to increase or decrease coiled-coil regions of HMW2, a major component protein of 200 kDa aligned in parallel along the cell axis. HMW2-engineered mutants produced both long and short attachment organelles, which we quantified by transmission electron microscopy and fluorescent microscopy with nano-meter precision. This simple design of HMW2 acting as a molecular ruler for the attachment organelle should provide an insight into bacterial cellular organization and its function for their parasitic lifestyles.
TL;DR: To correlate fast live cell imaging of polarized monolayer cells with scanning electron microscopy, a robust method is developed by using gold mesh grids as convenient CLSEM carriers for standard microscopes to unravel the morphology of the apical structures of monolayers of polarized epithelial cells at distinct time points during Salmonella infection.
Abstract: Live cell fluorescence imaging is the method of choice to visualize dynamic cellular processes in time and space, such as adhesion to and invasion of polarized epithelial cells by Salmonella enterica sv. Typhimurium. Scanning electron microscopy provides highest resolution of surface structures of infected cells, providing ultrastructure of the apical side of host cells and infecting Salmonella. Combining both methods toward correlative light and scanning electron microscopy (CLSEM) enables new insights in adhesion and invasion mechanisms regarding dynamics over time, and high spatial resolution with precise time lines. To correlate fast live cell imaging of polarized monolayer cells with scanning electron microscopy, we developed a robust method by using gold mesh grids as convenient CLSEM carriers for standard microscopes. By this, we were able to unravel the morphology of the apical structures of monolayers of polarized epithelial cells at distinct time points during Salmonella infection.
TL;DR: The ultrastructure of the pre- and post-metamorphic stages of the neotenic axolotl Ambystoma mexicanum was examined using light microscopy and both scanning and transmission electron microscopy to reveal whether there are any morphological changes associated with a switch in lifestyle as mentioned in this paper.
TL;DR: In this paper, the authors investigated ultrastructural details and the low molecular weight soluble carbohydrate composition of Tsunamia transpacifica (Stylonematophyceae) to get further insight into the adaptation to this uncommon habitat.
Abstract: The recently described red alga Tsunamia transpacifica (Stylonematophyceae) was previously isolated from plastic drift found at the pacific coast, but the natural habitat remains unknown. Here, we investigate ultrastructural details and the low molecular weight soluble carbohydrate composition to get further insight into the adaptation to this uncommon habitat. By means of high pressure freeze fixation, followed by freeze substitution, we could detect an up to 2-µm-thick cell wall surrounded by a distinct layer of extracellular polymeric substances (EPS), likely responsible for the adhering capacities of Tsunamia. The central position of the nucleus and multilobed parietal chloroplast, already observed by light microscopy, could be confirmed. The ultrastructure revealed large electron-dense bodies (EB) in the central cytoplasm, likely resembling degradation products of the chloroplast. Interestingly, these structures contained phosphorous and cobalt, and iron was found in smaller rounded electron-dense bodies by electron energy loss spectroscopy (EELS). Accumulation of these elements suggests a high biosorption activity of Tsunamia. Liquid chromatography-mass spectrometry (LC-MS) data showed the presence of two heterosides (floridoside and digeneaside) together with the polyol sorbitol, which are known as organic osmolytes and compatible solutes. Taken together, these are the first observations on ultrastructural details, element storage and accumulation of protective compounds are contributing to our understanding of the ultrastructural and osmotic solute basis for the ability of Tsunamia to thrive on plastic surfaces.
TL;DR: In this article, confocal laser scanning microscopy and transmission electron microscopy (TEM) were used to study the ultrastructural details and prophage components of Limnospira fusiformis.
Abstract: The alkaliphilic cyanobacterium Limnospira fusiformis is an integral part in food webs of tropical soda lakes. Recently, sudden breakdowns of Limnospira sp. blooms in their natural environment have been linked to cyanophage infections. We studied ultrastructural details and prophage components in the laboratory by means of confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). For a comparison at the subcellular level, we included transmission electron microscopy (TEM) material of infected cells collected during a field survey. Compared to TEM, CLSM has the advantage to rapidly providing results for whole, intact cells. Moreover, many cells can be studied at once. We chemically induced lysogenic cyanophages by means of mitomycin C (MMC) treatments and studied the ultrastructural alterations of host cells. In parallel, the number of cyanophages was obtained by flow cytometry. After treatment of the culture with MMC, flow cytometry showed a strong increase in viral counts, i.e., prophage induction. CLSM reflected the re-organization of L. fusiformis with remarkable alterations of thylakoid arrangements after prophage induction. Our study provides a first step towards 3D visualization of ultrastructure of cyanobacteria and showed the high potential of CLSM to investigate viral-mediated modifications in these groups.
TL;DR: In this article, the ultrastructure of all of the main components of the cornea in two different-sized individuals of the Little Penguin Eudyptula minor is presented. But, the authors have focused on two types of microprojections, microridges and microvilli found in central (flattened) and peripheral regions, respectively.
Abstract: The cornea is a specialized component of the vertebrate eye that provides protection, refractive power, transparency for optical imaging and mechanical support. However, the corneas of birds have received little attention with no comprehensive study of their functional morphology. Using light microscopy and both scanning and transmission electron microscopy, the first description of the ultrastructure of all of the main components of the cornea in two different-sized individuals of the Little Penguin Eudyptula minor is presented. Two types of microprojections protrude from the surface of the cornea with a predominance of microridges and microvilli found in central (flattened) and peripheral regions, respectively. Epithelial cell density is higher in peripheral cornea, especially in the larger (older) individual, while there is a reduction of epithelial cell density with age. The cornea comprises a thick epithelium uniquely attached to the basement membrane with numerous incursions rather than anchoring fibres and anchoring plaques as is found in other vertebrate corneas. Posterior to Bowman's layer, the orthogonally-arranged collagen fibril lamellae in the stroma form extensive branches and anastomoses. Descemet's membrane is well-developed with an anterior or foetal portion with long banding. However, the thickness of Descemet's membrane is larger in the older individual with the inclusion of an additional irregular pale-staining posterior portion. Polygonal endothelial cells extend across the cornea as a monolayer with often tortuous cell junctions. Endothelial cell density increases towards the periphery, but decreases with age. Primary cilia are observed protruding through the central region of some endothelial cells into the anterior segment but subsurface structures resembling cilia suggest that these features may be more common. The ultrastructure of the corneal components reveals a range of functional adaptations that reflect the amphibious lifestyle of this seabird.
09 Mar 2021
TL;DR: In this article, the authors used light and electron microscopy coupled with histochemistry to investigate the micromorphology, ultrastructure and histochemical properties of C. benghalensis leaves and stems.
Abstract: Commelina benghalensis L. is used as a traditional medicine in treating numerous ailments and diseases such as infertility in women, conjunctivitis, gonorrhea, and jaundice. This study used light and electron microscopy coupled with histochemistry to investigate the micromorphology, ultrastructure and histochemical properties of C. benghalensis leaves and stems. Stereo and scanning electron microscopy revealed dense non-glandular trichomes on the leaves and stems and trichome density was greater in emergent leaves than in the young and mature. Three morphologically different non-glandular trichomes were observed including simple multicellular, simple bicellular and simple multicellular hooked. The simple bicellular trichomes were less common than the multicellular and hooked. Transmission electron micrographs showed mitochondria, vesicles and vacuoles in the trichome. The leaf section contained chloroplasts with plastoglobuli and starch grains. Histochemical analysis revealed various pharmacologically important compounds such as phenols, alkaloids, proteins and polysaccharides. The micromorphological and ultrastructural investigations suggest that Commelina benghalensis L. is an economically important medicinal plant due to bioactive compounds present in the leaves and stems.
TL;DR: In arachnids, the Malpighian tubules (MTs), coxal glands and stercoral pockets are capable of collecting and removing excreta from the body as mentioned in this paper.
Abstract: In arachnids, the Malpighian tubules (MTs), coxal glands and stercoral pockets are capable of collecting and removing excreta from the body The presence of the MTs among Opiliones was evidenced for the first time in Amilenus aurantiacus in 2015 Individuals undergo a winter diapause subterranean habitats Here, we provided the morphological and cytological description of the MTs and asked whether their structure and ultrastructure change during the winter diapause We studied the changes using light and transmission electron microscopy The MTs consisted of the ureter and a pair of long, lateral blind-ended tubules, forming a long loop in the opisthosoma, and a coiled, terminal ball in the prosoma The MTs were uniform, composed of a single-cell type, a monolayer of cuboidal epithelial cells, and the basal lamina The cell ultrastructure was quite comparable to those in other arthropods, except for very long infoldings of the basal membrane protruding close to the nucleus Except for spherite exploitation, no changes were observed in the ultrastructure of the MT epithelial cells during overwintering We suggest that the analogous MTs in A aurantiacus, and the nephron anatomies, along with a single-cell-type MT epithelium, might be of advantage in modelled studies of the nephron