Small Globular Structures Research Articles

MpR2R3-MYB2 is a key regulator of oil body formation in Marchantia polymorpha.

MpMYB02, a regulator of marchantin accumulation, also acts as a key regulator of oil body formation. MpMYB02 induces the expression of MpSYP12B and promotes oil body formation, subsequently leading to marchantin accumulation. The oil body observed in Marchantia polymorpha is a cellular organelle surrounded by a unit membrane, accumulating various secondary metabolites such as marchantins and terpenes. We observed that oil body formation is regulated by MpMYB02, a key regulator of marchantin accumulation. In the Mpmyb02 mutant, no oil bodies were observed, although idioblast-like cells were present in the gemma. We introduced MpMYB02-glucocorticoid receptor (GR), a steroid-inducible transcriptional activator, into Mpmyb02 and assessed the effect of dexamethasone (DEX) on oil body formation. Following DEX treatment, transformed liverworts began forming oil bodies within 12h. During the initial stages of oil body development, we observed the aggregation of small globular structures. DEX treatment upregulated several genes implicated in oil body formation, including MpSYP12B. Our findings underscore that MpMYB02 plays a crucial role not only in marchantin accumulation but also in oil body formation.

Fabrication of chitosan/silica hybrid coating on AZ31 Mg alloy for orthopaedic applications

Biocompatible conversion of chitosan and chitosan/silica hybrid coating were prepared to enhance the biocompatibility and corrosion resistance of biodegradable AZ31 Mg alloy. The coatings were optimized and analysed with potentiodynamic polarization, SEM, ATR-IR and XPS studies. Potentiodynamic polarization studies, revealed that the coatings exhibited high corrosion resistance. The surface morphology of the Ch-3/Si coating showed small globular rough structure. The presence of functional groups was confirmed by ATR-IR. For a better understanding of chitosan/silica hybrid coating, the chemical states were examined by XPS studies. The in-vitro bioactivity of the coated samples was evaluated in Earle's solution, which formed a dense layer of coral-like structure and calcium-deficient apatite with less stoichiometric ratio than the hydroxyapatite. In-vitro cell culture studies exhibited a good cell proliferation rate and the fabricated Ch-3/Si coating was found to be non-hemolytic. The bacterial studies proved that Ch-3/Si coating possessed inherent antibacterial activity.

Evaluating the properties of organic and mineral sludge as a raw material for the production of sorption material

The comparative investigations of the physical and chemical properties of two large-tonnage organic and mineral wastes of agricultural raw materials processing - carbonate sediment (CS) formed during the processing of sugar beets and diatomaceous sludge (DS), which is a waste product of sunflower oil production were carried out in work. It was found that in both materials during burning, carbonization of organic substances occurs on the surface of the mineral core; heat treatment gives them hydrophobic properties, the pH of the aqueous extract has an alkaline reaction (for DS pH = 10.8, for CS pH = 11.5). The central part of the mineral component of CS is calcium carbonate, and DS is silicon oxide, CS has a more developed specific surface area, which is ensured by the presence of small globular structures. The oil capacity of the materials after heat treatment is 3.5 g/g for DS and 1.13 g/g for CS; dye capacity “methylene blue” for heat-treated CS is 77.9 mg/g, it is 9.5 mg/g for DS. Further research is needed to develop a method for sharing these materials for the effective treatment of multicomponent sewage.

A Robust Fungal Allomelanin Mimic: An Antioxidant and Potent π-Electron Donor with Free-Radical Properties that can be Tuned by Ionic Liquids.

Developing effective strategies to increase the chemical stability and to fine-tune the physico-chemical properties of melanin biopolymers by rational control of π-electron conjugation is an important goal in materials science for biomedical and technological applications. Herein we report that poly-1,8-dihydroxynaphthalene (pDHN), a non-nitrogenous, catechol-free fungal melanin mimic, displays a high degree of structural integrity (from MALDI-MS and CP/MAS 13 C NMR analysis), a strong radical scavenging capacity (DPPH and FRAP assays), and an unusually intense EPR signal (g=2.0030). Morphological and spectral characterization of pDHN, along with deassembly experiments in ionic liquids, indicated amorphous aggregates of small globular structures with an estimated stacking distance of 3.9 Å and broadband absorption throughout the visible range. These results indicate that DHN-based melanins exhibit a high structural integrity and enhanced antioxidant and free-radical properties of potentially greater biomedical and technological relevance than for typical indole-based eumelanins.

Impact of plasma treatment under atmospheric pressure on surface chemistry and surface morphology of extruded and injection-molded wood-polymer composites (WPC)

The influence of plasma treatment performed at atmospheric pressure and ambient air as process gas by a dielectric barrier discharge (DBD) on the morphological and chemical surface characteristics of wood-polymer composites (WPC) was investigated by applying several surface-sensitive analytical methods. The surface free energy showed a distinct increase after plasma treatment for all tested materials. The analyzing methods for surface topography—laser scanning microscopy (LSM) and atomic force microscopy (AFM)—revealed a roughening induced by the treatment which is likely due to a degradation of the polymeric surface. This was accompanied by the formation of low-molecular-weight oxidized materials (LMWOMs), appearing as small globular structures. With increasing discharge time, the nodules increase in size and the material degradation proceeds. The surface degradation seems to be more serious for injection-molded samples, whereas the formation of nodules became more apparent and were evenly distributed on extruded surfaces. These phenomena could also be confirmed by scanning electron microscopy (SEM). In addition, differences between extruded and injection-molded surfaces could be observed. Besides the morphological changes, the chemical composition of the substrates’ surfaces was affected by the plasma discharge. Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the formation of new oxygen containing polar groups on the modified surfaces.

Genomic and phenotypic characterization of an atypical Aeromonas salmonicida strain isolated from a lumpfish and producing unusual granular structures.

Aeromonas salmonicida strains are roughly classified into two categories, typical and atypical strains. The latter mainly regroup isolates that present unusual phenotypes or hosts, comparatively to the typical strains that belong to the salmonicida subspecies. This study focuses on an uncharacterized atypical strain, M18076-11, isolated from lumpfish (Cyclopterus lumpus) and not part of the four recognized Aeromonas salmonicida subspecies. This isolate presents an unreported phenotype in the A.salmonicida species: the formation of large granular aggregates. Granules are formed of a heterogeneous mix of live and dead cells, with live cells composing the majority of the population. Even if no mechanism was determined to cause cellular aggregation, small globular structures at the cell surface were observed, which might affect granular formation. Pan-genome phylogenetic analysis indicated that this strain groups alongside the masoucida subspecies. However, phenotypic tests showed that these strains have diverging phenotypes, suggesting that M18076-11 might belong to a new subspecies. Also, a pAsal1-like plasmid, which was only reported in strains of the subspecies salmonicida, was discovered in M18076-11. This study sheds light on unsuspected diversity in A.salmonicida subspecies and stresses the need of thorough identification when a new strain is encountered, as unique traits might be discovered.

Melatonin attenuates the mitochondrial translocation of mitochondrial fission proteins and Bax, cytosolic calcium overload and cell death in methamphetamine-induced toxicity in neuroblastoma SH-SY5Y cells

Methamphetamine (METH) is an addictive drug that can cause toxicity and degeneration in the brain. Several pieces of evidence have demonstrated that METH toxicity results in increases in oxidative stress that regulate an intracellular signaling cascade that leads to cell death. Recently, several studies have emphasized that the overload of cytosolic calcium levels and mitochondrial fission into a small mitochondrial structure is involved in cell death processes. In the present study, we aimed to investigate the effects of METH toxicity on cytosolic calcium overload and mitochondrial fission in neuroblastoma SH-SY5Y cells. Additionally, the protective effect of melatonin against METH-induced toxicity was also investigated. The results of the present study demonstrated that METH significantly decreases cell viability and increases the levels of mitochondrial fission (Fis1 and Drp1) proteins and pro-apoptotic protein, Bax in isolated mitochondria. The levels of Drp1 in the cytosol of METH-treated cells had no significant differences compared to the control untreated cells. METH also significantly increased the cytosolic calcium levels. Melatonin reversed the toxic effects of METH by restoring cell viability and inhibiting the increase in mitochondrial Fis1 levels and the mitochondrial translocation of Drp1 and Bax. Additionally, melatonin was able to reduce the METH-induced increase in cytosolic calcium levels and fragmented mitochondria into small globular structures in SH-SY5Y cells. The results of the present study demonstrate the potential abilities of melatonin to maintain the homeostasis of mitochondrial dynamics and cytosolic calcium levels in METH-induced toxicity in neuronal cells.

Melatonin attenuates methamphetamine‐induced disturbances in mitochondrial dynamics and degeneration in neuroblastoma SH‐SY5Y cells

Methamphetamine (METH) is a psychostimulant drug that can cause toxicity and degeneration in the brain. The toxicity due to METH involves multiple pathways, including the mitochondrial-dependent death pathway. Several pieces of evidence have emphasized that the fragmentation of mitochondria into smaller structures plays some role in the cell-death process. In this study, we investigated the role of mitochondrial dynamics in METH-induced toxicity in human dopaminergic neuroblastoma SH-SY5Y cultured cell lines. In addition, the protective effect of melatonin against METH-induced toxicity was investigated. Our results show that METH significantly decreased cell viability and increased the levels of the mitochondrial fission protein, Fis1 and the Drp1 oligomer. However, the levels of the mitochondrial fusion proteins OPA1 and Mfn1 did not change in METH-treated cells. Melatonin can reverse the toxic effects of the METH-induced reduction in cell viability and the production of the Fis1 protein and the Drp1 oligomer. Moreover, the morphological alteration of mitochondria was investigated in METH-treated cells in the presence of melatonin using transmission electron microscopy (TEM). At 24hr after METH exposure, typical cell shrinkage was observed in SH-SY5Y cells. Mitochondria were fragmented into small globular structures in a large proportion of METH-treated cells, but tubular networks of mitochondria were present in large proportions of control-untreated cells and METH-treated cells in the presence of melatonin. The results of the present study demonstrate the potential of melatonin to reduce cell death and restore mitochondrial function in neurons affected by METH-induced toxicity.

Microstructural Evolution of Solid-solution-treated Zn–22Al in the Semisolid State

The effect of solid-solution-treatment on the semisolid microstructure of Zn–22Al with developed dendrites was investigated. Forming Zn–22Al products by semisolid metal processing offers significant advantages, such as reductions in macro-segregation, porosity and forming costs. Thermal and microstructural analyses of the formed Zn–22Al alloy were performed by differential scanning calorimetry, scanning electron microscopy and optical microscopy. The changes in the microstructures and phase transformation in response to various solid-solution-treatments were analysed. In this study, as-cast samples were held isothermally at 330 °C for 0.5–5 h and then partially remelted at a semisolid temperature of 438 °C for 1 h to produce a solid-globular grain structure in a liquid matrix. A non-dendritic semisolid microstructure could not be obtained when the traditionally cast Zn–22Al alloy with developed dendrites was subjected directly to partial remelting. After solid-solution-treatment at 330 °C, the black interdendritic eutectics were dissolved, and the dendritic structures gradually transformed into uniform β structures when the treatment time was increased. The coarsened and merged dendrites were separated as a result of penetration by the liquid phase and melting of the residual eutectic at sites along the former grain boundaries. The microstructure of the solid-solution-treated sample transformed into a small globular structure; the best shape factor of 0.9, corresponding to a particle size of 40 ± 16 μm, is achieved when the sample was treated for 3 h followed by direct partial remelting into its semisolid zone.

A study of the distribution and density of the VEGFR-2 receptor on glioma microvascular endothelial cell membranes.

The purpose of the study was to examine the nanoscale distribution and density of the VEGFR-2 membrane receptor on the endothelial cell surface of glioma microvasculature. Immunofluorescence and atomic force microscopy combined with immunogold labeling techniques were used to characterize and determine the position of the glioma microvasculature endothelial cell surface receptor VEGFR-2. We aimed to indirectly detect the distribution of VEGFR-2 on the cell membrane at the nanoscale level and to analyze VEGFR-2 quantitatively. Immunofluorescence imaging showed a large amount of VEGFR-2 scattered across the endothelial cell surface; atomic force microscopy imaging also showed two globular structures of different sizes scattered across the endothelial cell surface. The difference between the average diameter of the small globular structure outside the cell surface (43.67 ± 5.02 nm) and that of IgG (44.61 ± 3.19 nm) was not statistically significant (P > 0.05). The three-dimensional morphologies of the small globular structure outside the cell surface and IgG were similar. The difference between the average diameter of the large globular structure outside the cell surface (74.19 ± 9.10 nm) and that of IgG-SpA-CG (74.54 ± 15.93 nm) was also not statistically significant (P > 0.05). The three-dimensional morphologies of this large globular structure outside the cell surface and IgG-SpA-CG were similar. The total density of these two globular structures within the unit area was 92 ± 19 particles μm(2). No globular structures were seen on the cell surface in the control group. The large globular structure on the surface of glioma microvascular endothelial cells was categorized as a VEGFR-2-IgG-SpA-CG immune complex, whereas the small globular structure was categorized as a VEGFR-2-IgG immune complex. The positions of the globular structures were the same as the positions of the VEGFR-2 molecules. A large amount of VEGFR-2 was scattered across glioma microvascular endothelial cell surfaces; the receptor density was about 92 per square micron.

Superresolution Imaging of Intact Microbial Communities Reveals Molecular Architecture of Biofilm Development and Bacterial Organization

Most bacteria live as a biofilm community in their natural habitat. This surface-attached social life form is commonly found in antibiotic-resistant infections and chronic diseases. For example, bacterial biofilms are a leading cause of lung infection and death among cystic fibrosis patients. Biofilms are also crucial for bioenergy research since cellulose degrading bacteria in the gut of termites are organized as heterogenic biofilms and believed to communicate throughout these tissue-like structures. To gain structural and molecular insight on biofilm formation, we imaged intact bacterial biofilms at different developmental stages without using any fixing agents by STORM microscope. These three-dimensional superresolution images revealed ten to twenty biofilm-promoting exopolysaccharide-rich regions that are sparsely distributed on the cell surface. A few hours after surface attachment of bacteria, these small globular structures expanded to ∼100 nm in size and protruded from the cell surface. During the initial stage of biofilm formation, we observed extensive interactions among neighboring cells through these globular exopolysaccharides. Moreover, we identified straight cable-like cell-to-cell and cell-to-substrate connections, up to 5 microns in length, originating from globular structures. These physical interactions may explain how bacteria form initial microcluster on the surface, first stage of commitment to biofilm formation. Microcluster formation depends on bacterial twitching motility on the surface and exopolysaccharide synthesis.These results are shifting the paradigm in the biofilm field which states that bacteria are randomly embedded in an extracellular matrix in biofilms. Our data suggests that bacteria actively build their house similar to a spider web by synthesizing sticky globular polysachharides on the cell surface, which are then extended to cable-like structures by twitching motility on the surface.

Improved localization of cellular membrane receptors using combined fluorescencemicroscopy and simultaneous topography and recognition imaging

The combination of fluorescence microscopy and atomic force microscopy has a greatpotential in single-molecule-detection applications, overcoming many of the limitationscoming from each individual technique. Here we present a new platform of combinedfluorescence and simultaneous topography and recognition imaging (TREC) for improvedlocalization of cellular receptors. Green fluorescent protein (GFP) labeled humansodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cellsand endothelial cells (MyEnd) from mouse myocardium stained with phalloidin-rhodaminewere used as cell systems to study AFM topography and fluorescence microscopy on thesame surface area. Topographical AFM images revealed membrane features such aslamellipodia, cytoskeleton fibers, F-actin filaments and small globular structures withheights ranging from 20 to 30 nm. Combined fluorescence and TREC imaging was appliedto detect density, distribution and localization of YFP-labeled CD1d molecules onα-galactosylceramide(αGalCer)-loaded THP1 cells. While the expression level, distribution and localization of CD1dmolecules on THP1 cells were detected with fluorescence microscopy, the nanoscaledistribution of binding sites was investigated with molecular recognition imaging by using achemically modified AFM tip. Using TREC on the inverted light microscope, the recognitionsites of cell receptors were detected in recognition images with domain sizes ranging from ∼ 25 to ∼ 160 nm, with the smaller domains corresponding to a single CD1d molecule.

Scanning Electron Microscopy of the Orbital Harderian Gland in the Male Atlantic Bottlenose Dolphin (Tursiops truncatus)

The ultrastructure of the Harderian gland of Atlantic bottlenose dolphin (Tursiops truncatus) was examined by scanning electron microscopy (SEM). We found the following surface features: the typical round appearance of the ascinar glandular unit with a finely granular surface, a thin cortex and immediately below two types of cells: type I cells (characterized by small lipid vacuoles) and type II cells (characterized by large lipid vacuoles). It has been suggested that different cells forms represent a single cell type in varying activity states. Additionally, a coalescent tubular complex, a small balloon-like structures and large globular structures were observed. These structures may be reservoirs of secretion products.

High resolution scanning tunnelling microscopy of the β-amyloid protein (Aβ1–40) of Alzheimer’s disease suggests a novel mechanism of oligomer assembly

The aggregation of the β-amyloid protein (Aβ) is an important step in the pathogenesis of Alzheimer’s disease. There is increasing evidence that lower molecular weight oligomeric forms of Aβ may be the most toxic species in vivo. However, little is known about the structure of Aβ oligomers. In this study, scanning tunnelling microscopy (STM) was used to examine the structure of Aβ monomers, dimers and oligomers. Aβ1–40 was visualised by STM on a surface of atomically flat gold. At low concentrations (0.5 μM) small globular structures were observed. High resolution STM of these structures revealed them to be monomers of Aβ. The monomers measured approximately 3–4 nm in diameter. Internal structure was seen in many of the monomers consistent with a conformation in which the polypeptide chain is folded into 3 or 4 domains. Oligomers were seen after ageing the Aβ solution for 24 h. The oligomers were also 3–4 nm in width and appeared to be formed by the end-to-end association of monomers with the polypeptide chain oriented at 90° to the axis of the oligomer. The results suggest that the oligomer formation can proceed through a mechanism involving the linear association of monomers.

A microscopic view of miniprotein folding: Enhanced folding efficiency through formation of an intermediate

The role of polypeptide collapse and formation of intermediates in protein folding is still under debate. Miniproteins, small globular peptide structures, serve as ideal model systems to study the basic principles that govern folding. Experimental investigations of folding dynamics of such small systems, however, turn out to be challenging, because requirements for high temporal and spatial resolution have to be met simultaneously. Here, we demonstrate how selective quenching of an extrinsic fluorescent label by the amino acid tryptophan (Trp) can be used to probe folding dynamics of Trp-cage (TC), the smallest protein known to date. Using fluorescence correlation spectroscopy, we monitor folding transitions as well as conformational flexibility in the denatured state of the 20-residue protein under thermodynamic equilibrium conditions with nanosecond time resolution. Besides microsecond folding kinetics, we reveal hierarchical folding of TC, hidden to previous experimental studies. We show that specific collapse of the peptide to a molten globule-like intermediate enhances folding efficiency considerably. A single point mutation destabilizes the intermediate, switching the protein to two-state folding behavior and slowing down the folding process. Our results underscore the importance of preformed structure in the denatured state for folding of even the smallest globular structures. A unique method emerges for monitoring conformational dynamics and ultrafast folding events of polypeptides at the nanometer scale.

Ruptured bronchial artery aneurysm associated with sarcoidosis

J Thorac Cardiovasc Surg 2003;125:1153-4

Development of Pyrenopeziza brassicae apothecia on agar and oilseed rape debris

The development of apothecia of Pyrenopeziza brassicae (anamorph Cylindrosporium concentricum) on oilseed rape debris and compost malt agar was observed by scanning electron and light microscopy. On oilseed rape debris, apothecia developed directly beneath the epidermis as small globular structures of dense mycelium, which protruded through the epidermis as they increased in size. The apices of erumpent immature apothecia then developed small ostiolar openings which increased in diameter to expose the hymenia of mature apothecia containing dome-shaped asci interspersed with filiform paraphyses. On compost malt agar, hyphae of one mating type grew towards hyphae of the opposite mating type 3-4 d after inoculation of conidia onto agar surfaces. The subsequent development of apothecia on compost malt agar was similar to that on oilseed rape debris.

Fossilized metazoan embryos—The historical testimony of the Cambrian explosion

IN zoology, the developmental stage of individual from zygote to hatching was called embryo. The modem embryology is a branch of study on the organism’ s embryos. The palaeoembryology is a new field in palaeontology, and it has not been considered an important field before, because the invertebrate’s eggs or embryos are minute size and without mineralized envelope. Until now, fossilized eggs of invertebrates in Cambrian have been rarely reported and most of them are small globular structures without recognizable features. Other reported fossilized embryos found from Middle Cambrian are spherical with a smooth

Induction of In Vitro Cultured Masses of Shoot Primordia of Hybrid Statice and Its Cryopreservation by Vitrification

Bulbous structures consisting of meristematic clumps (designated “shoot primordia”) were induced from a meristematic culture of a hybrid statice (Limonium altaica Mill. × L. caspium Mill., cv. Blue Symphonet). The shoot tips were cultured in 25 mL of liquid 1/2 Murashige & Skoog (MS) medium supplemented with 0.44 μm BA and 0.054 μm NAA and 3% sucrose at pH 5.8 by vertically shaking at 2 rpm on rotating stages (1 m in diameter) at 25 °C. One month after inoculation of shoot tips, numerous small globular structures were formed and propagated vegetatively at a high rate following subculture. Segments of shoot primordia had developed into plantlets 2 weeks after transfer to solidified 1/2 MS medium supplemented with 0.44 μm BA and 1% sucrose. Plantlets successfully acclimated and grew into normal plants in a greenhouse. Cold-hardened, precultured small segments of shoot primordia were successfully cryopreserved in liquid N by vitrification. Vitrified and warmed segments plated on solidified 1/2 MS medium produced shoots about 21 d after plating. Cultured masses of shoot primordia appear promising for large-scale production and cryopreservation of annual and biennial statice. Chemical names used: 6-benzyladenine (BA); 1-naphthaleneacetic acid (NAA).

Structural and cell-adhesive properties of three recombinant fragments derived from perlecan domain III.

Domain III of the basement membrane proteoglycan perlecan was produced as three overlapping fragments in stably transfected mammalian cell clones. These recombinant fragments (43-48 kDa) were obtained in purified form and showed complete immunological cross-reactivity with perlecan, indicating their native structure. Rotary shadowing electron microscopy of each fragment demonstrated a small globular structure connected to a short rod. These data were interpreted to indicate that domain III has an elongated shape of 30 nm in length and consists of alternating globular domains (L4 modules) and short connecting segments attributed to tandem arrays of LE (laminin-type of EGF-like) modules which form rod-like segments in laminins. Sequence analyses of pepsin fragments were consistent with the disulfide-bonding patterns known for these modules from studies with laminin fragments, but two additional disulfide loops were also identified. Several cell lines which attached to mouse perlecan and/or human fibronectin failed to adhere to the domain III fragments, despite the fact that one of them contained an RGD (Arg-Gly-Asp) site in the L4 module. Furthermore, no significant binding was observed in solid phase binding assays with alpha 5 beta 1 and alpha v beta 3 integrins underscoring the low activity or accessibility of the RGD site.