Vesicle Walls Research Articles

Aquaporin channels in desalination: Mechanical properties and operational load analysis

The scarcity of freshwater sources and the global demand for drinking water have spurred researchers worldwide to develop new and efficient desalination and water purification technologies. One promising method is desalination using aquaporin (AQP) channels, which are highly regarded for their biocompatibility and exceptional desalination efficiency. However, there is limited information on the mechanical behavior of these proteins under operational loads and how they maintain their function and resilience over time. This research employs all-atom molecular dynamics simulation to calculate the mechanical properties of the channels at the nanoscale. It also uses the finite element method to analyze the behavior of channels in vesicles embedded in composite plates at the macroscale under operational loads and conditions. Our research shows that the force on vesicle walls changes considerably with applied pressure, peaking at 14 pN at 55 bar. This variability highlights the need to carefully assess the weakest parts of the nanochannels, especially the helices HB and H1, which are susceptible to high strain and possible unfolding under extended stress. The results indicate the force tolerance threshold of the subsystems, guiding the application of appropriate force conditions for optimal performance and long-term system maintenance. Beyond desalination systems, the findings offer useful information for researchers working with aquaporin nanochannels in applications such as targeted drug release systems based on protein nanovalves, solid-state sequencing systems, and more.

Diabetes Mellitus and Respiratory Function in Smokers Eligible for Coronary Artery Bypass Grafting

Diabetics' respiratory systems are characterized by fibroblast and vascular endothelial proliferation, increased density of pulmonary microspheres, and thickening of pulmonary vesicle walls due to increased collagen and elastin. These sorts of damage to the alveolar-capillary barrier, as well as reductions in pulmonary capacity and flow, hurt the body's functionality. Investigate the possible links between diabetes and respiratory parameters in smokers who are candidates for coronary artery bypass grafting. Assess early changes in lung volumes in smoking individuals before and after CABG using pulmonary function tests and determine how diabetes may influence these changes by comparing diabetic and non-diabetic patients. This was a prospective controlled study of 200 consecutive individuals who underwent elective coronary artery bypass surgery. Two hundred fifty-six patients were accepted to our study, but 56 were excluded (41 did not match our inclusion criteria, and 15 declined to participate), leaving us with 200 cases. There was a statistically significant difference between diabetes and non-diabetic subjects on lung function testing. Patients with diabetes who qualified for CABG showed poorer spirometry parameters than those without diabetes. This suggests that these individuals require respiratory examinations and treatment to improve their respiratory performance before and following cardiac surgery.

Decorated Vesicles as Prebiont Systems (a Hypothesis).

Decorated vesicles in deep, seafloor basalts form abiotically, but show at least four life-analogous features, which makes them a candidate for origin of life research. These features are a physical enclosure, carbon-assimilatory catalysts, semi-permeable boundaries, and a source of usable energy. The nanometer-to-micron-sized spherules on the inner walls of decorated vesicles are proposed to function as mineral proto-enzymes. Chemically, these structures resemble synthetic FeS clusters shown to convert CO2, CO and H2 into methane, formate, and acetate. Secondary phyllosilicate minerals line the vesicles' inner walls and can span openings in the vesicles and thus can act as molecular sieves between the vesicles' interior and the surrounding aquifer. Lastly, basalt glass in the vesicle walls takes up protons, which replace cations in the silicate framework. This results in an inward proton flux, reciprocal outward flux of metal cations, more alkaline pH inside the vesicle than outside, and production of more phyllosilicates. Such life-like features could have been exploited to move decorated vesicles toward protolife systems. Decorated vesicles are proposed as study models of prebiotic systems that are expected to have existed on the early Earth and Earth-like exoplanets. Their analysis can lead to better understanding of changes in planetary geocycles during the origin of life.

Reconstructing the timing and conditions of fragmentation from water speciation in ash during a deep submarine eruption: 2012 eruption of Havre, Kermadec Arc

The lack of visual observations and difficulty recreating ambient conditions in the laboratory mean deep subaqueous volcanic eruptions (>500 m water depth) remain enigmatic. However, the pressure and temperature dependency of water speciation and solubility in volcanic melts and glasses, and water's high diffusion rate, offers a potential window into the processes and conditions during deep subaqueous volcanism.The 2012 submarine eruption of Havre Volcano is the ideal laboratory in which to use water species distributions to understand submarine eruption processes. Post-eruption AUV mapping, and ROV observation and sampling generated an unprecedented amount of contextual information for a deep submarine eruption including on the magma ascent conditions, eruption sequence, and magma fragmentation. Here we present high spatial resolution synchrotron-FTIR measurements of water speciation in glassy ash (125–500 μm) from several subunits (1, 2 and 3) of a widespread ash with lapilli deposit produced in the 2012 eruption.Measurements record OH depletion profiles around vesicles, along with H2Omol enrichment profiles. In several thick vesicle walls far-field regions unaffected by processes at the bubble margins have also been identified. By focusing on OH concentrations, which is effectively non-diffusing below the glass transition, we can remove the effects of secondary rehydration and calculate the pressure and water depth at which ash grain quenched.Far-field regions record quench depths within the 650–900 m water depth range for pre- and post- eruption vent depth, suggesting ash grains equilibrated at vent depth. OH depletion profiles produce quench pressures on vesicle margins typically corresponding to 200–400 m water depth shallower, suggesting a 2–4 MPa decompression before ash quench. Diffusion modelling suggests that at eruption temperature the observed OH depletion profiles formed through exsolution in <2 s. The difference in quench pressure within the ash is not reflective of a difference in the depth of quenching. Rather it is reflective of the rapidity of the quench process relative to the diffusion rate.The results imply transient low-pressure conditions formed during ash generation in the 2012 Havre eruption. We discuss several physical processes in the context of submarine volcanism that may explain the formation of transient low-pressure regions. The results have implications for how we understand submarine eruption processes and highlight the potential of high resolution FTIR for studying submarine volcanism.

The origins of transparent and non-transparent white pumice: A case study of the 52 ka Maninjau caldera-forming eruption, Indonesia

The VEI 7 (220–250 km3), a 52 ka eruption of the Maninjau caldera in Indonesia produced two distinct types of white pumices: transparent (TWP) and non-transparent (NTWP). These pumices were identified on outcrops, based on their qualitative traits, without the use of laboratory analyses (geochemical and textural). TWPs are typically fragile, irregular in shape, and have a transparent glass of vesicle walls around visible large vesicles, whereas NTWPs are relatively strong, blocky in shape, and have a non-transparent glass due to invisible small vesicles. Based on chemical and petrographical analyses, both pumice types were crystal-poor (avg. of 3.3%), with similar mineralogy, glass compositions (avg. 78.5 wt% SiO2), and plagioclase core compositions (avg. of An28). From component analysis, we found that the abundance of TWP decreased towards the upper stratigraphic ignimbrite deposits, along with an increase in NTWP, grey pumice, banded pumice, and lithic (non-juvenile) contents. We defined two vesicle populations with a threshold diameter of 0.1 mm based on bimodal vesicle size distributions by textural analysis for TWP and NTWP. Large vesicles correspond to preexisting bubbles that form in the magma chamber (pheno-vesicle, > 0.1 mm), whereas small vesicles in the groundmass (matrix-vesicle, < 0.1 mm) are attributed to second nucleation in the conduit during the eruption. We performed a comparison using vesicle data (pheno- and matrix-vesicles) for these two white pumice types. Pheno- and matrix-vesicularity showed a negative correlation. Thus, the boundary between TWP and NTWP was also quantitatively confirmed by the volume fraction ratio of the pheno- and matrix-vesicles. This evidence suggests that TWP originated from pheno-bubble-dominated magma (at least 0.1% volume fraction of pheno-bubbles in the magma chambers), whereas NTWP originated from pheno-bubble-poor magma. The variation in the abundance of TWP and NTWP in the stratigraphic positions implies the rough stratification of pre-existing bubbles (pheno-bubbles) in the pre-eruptive magma chamber, where the overpressure developed to trigger and drive the eruption. The two regimes control the formation of matrix-vesicles: (1) a pheno-bubble-controlled regime, and (2) a decompression-controlled regime. Based on a correlation between pheno-vesicle number density (PVND) and matrix-vesicle number density (MVND) together with numerical calculations based on a previous study, we suggest that the TWPs with the highest pheno-vesicularity formed under conditions corresponding to the first regimes, while the NTWPs formed in the second regime, where MVND is mostly determined by decompression rate. We also argue that NTWP is the only representative juvenile for estimating magma decompression rate, as the MVND value in TWP do not represent the actual second nucleation processes. Therefore, the occurrence of NTWP in the entire deposits with a relatively similar MVNDs value might suggest that the early and final eruption stages experienced a relatively similar magma decompression rate.

Magmatic and phreatomagmatic contributions on the ash-dominated basaltic eruptions: Insights from the April and November–December 2005 paroxysmal events at Karthala volcano, Comoros

Basaltic eruptions are commonly associated with lava emissions and relatively weak explosive activities, but they can sometimes produce strong explosive eruptive phases. In April and November 2005, two paroxysmal eruptive events occurred within the summit crater of Karthala basaltic shield volcano (Grande Comore Island, Comoros), which hosted a water lake before each of these events. Both 2005 ash plumes spread across the Comoros Archipelago and heavily impacted the whole Grande Comore Island. Associated deposits on the volcano summit are extremely fine-grained (up to 50 wt% of fine ash <63 μm for some analyzed layers) and rich in millimeter-sized rounded accretionary lapilli aggregates. Field observations, as well as textural and chemical analyses performed on both coarse- and fine-grained pyroclasts permit to identify juvenile and non-juvenile components and quantify their peculiar characteristics. Coarse ash (710–1000 μm) mainly consists of juvenile pumice particles (vesicle number density NV = 4.5 104 mm−3 and gas to melt ratio VG/VL = 1.5, on average), characterized by glassy groundmasses and representative of magma portions ascending quickly within the eruptive conduits (up to 10 m s−1). A relatively low amount of juvenile scoria particles are also observed in the coarse ash fractions, which are characterized by magma degassing (NV = 4.7 104 mm−3 and VG/VL = 0.5 on average) and associated crystallization (occurrence of dendritic microlites). Non-juvenile fragments (from blocks to coarse ash) are dense lava or intrusive fragments. Their amount decreases exponentially towards the fine ash fractions, which are mainly composed of juvenile, blocky, dense and glassy particles that are characterized by unambiguous textural signs of brittle fragmentation (hackle lines, stepped features and cracks). We support that Molten Fuel-Coolant Interactions between highly porous fast ascending basaltic magmas and external waters occurred during the paroxysmal phases of the studied eruptions, leading to a brittle-dominant and efficient regime of magma fragmentation. Variable but large amount of fine ash grains through the stratigraphic depth of the deposits can be ascribed to the brittle failure of the vesicle walls of the initial porous magma. Concurrently, thermohydraulic explosions caused the host rock fragmentation at shallow level, generating the relatively coarse non-juvenile particles. A short-lived episode of intense lava fountaining associated with steam explosions eventually occurred at the end of the November 2005 paroxysm, forming the last and relatively coarse tephra layer at the top of the studied eruptive sequence. Each paroxysmal phase lasted about a day as each associated water lake and shallow water table progressively vaporized and dried away. Both eruptions ended with lava pond and weak lava fountaining activities confined within the summit crater. We conclude that the contributions of both magmatic processes and phreatomagmatic interaction mechanisms ultimately generated the grain size, grain component and grain texture variabilities observed within the paroxysmal deposits. This work contributes to a better understanding of the generation of unusual fine ash from basaltic explosions as well as their eruptive dynamics and associated mechanisms, from magma ascent in the conduit to the fragmentation level and the interaction with intra-crateric lake waters.

Seminal Vesicles and Bulbourethral Glands of Mammals: Morphology, Physiology, Ecology, Action of Extreme Destabilizing Factors

In mammals, the adnexal sex glands are represented by seminal vesicles, the prostate gland, urethral and bulbourethral glands, as well as glands that coagulate sperm and ampullary glands. The secret of the accessory genital glands increases the volume of the ejaculate (the share of secretions of these glands accounts for about 95% of the volume of ejaculate) promotes sperm, causes increased contraction of smooth muscle cells in the walls of the female genital tract.The purpose of this review is to analyze the morphofunctional organization of seminal vesicles and bulbourethral glands of mammalian animals and humans.The presence or absence of seminal vesicles is a species-specific feature. Among mammals, seminal vesicles are well developed in some rodents, insectivores, a number of domestic animals (cattle, pigs), and primates. These glands are absent in cloacae, marsupials, some carnivores, a number of insectivores, artiodactyls. Bulbourethral glands are well developed in rodents, bats, primates, and some ungulates.In the wall of the seminal vesicles, the mucous, muscular and outer membranes are isolated. The epithelium of the secretory parts is pseudomultitial, the interstitium is represented by loose fibrous connective tissue and a significant number of smooth muscle cells. In the wall of the bulbourethral glands, the mucosa and adventitial membrane are isolated. The secretory end sections of the bulbourethral glands are lined with a single-layer single-row epithelium, glandular cells produce a mucosal or mixed secret. The seminal vesicles and bulbourethral glands are androgen-dependent glands. In species with a seasonal pattern of reproduction, their morphofunctional characteristics undergo significant changes during the circannual rhythm of reproduction.The epithelium of seminal vesicles and bulbourethral glands is very sensitive to the action of various adverse factors (heavy metal compounds, organic xenobiotics, electromagnetic radiation, ultrasound, etc.). When exposed to various negative factors in the adnexal glands, a complex of changes occurs (edema of connective tissue and epithelium, decreased secretory activity of epithelial cells, desynchronization of the secretory cycle, desquamation of glandular epithelial cells, proliferation of interstitial connective tissue).There is a lack of information on many aspects of the characteristics of the adnexal glands of the male reproductive system, primarily on the morphology and physiology of the adnexal glands of animals in natural ecosystems, on the ultrastructural and immunohistochemical characteristics of these glands, as well as on the mechanisms of regulation of morphofunctional rearrangements of the adnexal glands during seasonal reproduction rhythms, in the conditions of adaptation to various negative influences.

Effect of hydration on morphology of thin phosphonate block copolymer electrolyte membranes studied by electron tomography

AbstractThe morphological changes of phosphonate polypeptoid electrolyte membranes, poly‐N‐(2‐ethyl)hexylglycine‐block‐poly‐N‐phosphonomethylglycine (pNehm‐b‐pNpmn), in hydrated and dry states were characterized by cryogenic transmission electron microscopy (cryo‐TEM) and cryogenic electron tomography (cryo‐ET). The analysis of 3D tomograms revealed that the pNeh9‐b‐pNpm9 thin films absorbed a large amount of water, resulting in the formation of membranes that were nearly flat and giant multicompartment vesicles dispersed in the water phase. A simple lamellar phase appeared when the films were dried. In contrast, pNeh18‐b‐pNpm18 thin films absorbed little water and formed small highly curved unilamellar and multilamellar vesicles. Water was located mainly outside the closely‐packed vesicles. When water was removed by drying, the walls of adjacent vesicles collapsed to form honeycomb‐like capsules. The changes in domain size reflected changes in chain conformations. The pNpm9 blocks were saturated by water and fully extended, while pNpm18 blocks were neither saturated by water nor fully extended. In addition, the thicknesses of hydrophobic blocks in the hydrated films of both pNeh9‐b‐pNpm9 and pNeh18‐b‐pNpm18 were smaller than those in the dry films, reflecting an increase of the average distance between the neighboring junctions of polypeptoid molecules.

Encapsulation of inorganic nanoparticles in a block copolymer vesicle wall driven by the interfacial instability of emulsion droplets

We proposed an effective route, i.e., three-dimensional confined co-assembly of block copolymers and inorganic nanoparticles, to efficiently encapsulate high-density and large-size nanoparticles into the wall of polymeric vesicles.

Self-Assembly of Linear Amphiphilic Pentablock Terpolymer PAAx-PS48-PEO46-PS48-PAAxin Dilute Aqueous Solution.

A series of linear amphiphilic pentablock terpolymer PAAx-b-PS48-b-PEO46-b-PS48-b-PAAx (AxS48O46S48Ax) with various lengths x of the PAA block (x = 15, 40, 60, and 90) were synthesized via a two-step atom transfer radical polymerization (ATRP) using Br-poly(ethylene oxide)-Br (Br-PEO46-Br) as the macroinitiator, styrene (St) as the first monomer, and tert-butyl acrylate (tBA) as the second monomer, followed with the hydrolysis of PtBA blocks. The AxS48O46S48Ax pentablock terpolymers formed micelles in dilute aqueous solution, of which the morphologies were dependent on the length x of the PAA block. Cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and zeta potential measurement were employed to investigate the morphologies, chain structures, size, and size distribution of the obtained micelles. The morphology of AxS48O46S48Ax micelles changed from spherical vesicles with ordered porous membranes to long double nanotubes, then to long nanotubes with inner modulated nanotubes or short nanotubes, and finally, to spherical micelles or large compound vesicles with spherical micelles inside when x increased from 15 to 90. The hydrophobic PS blocks formed the walls of vesicles and nanotubes as well as the core of spherical micelles. The hydrophilic PEO and PAA block chains were located on the surfaces of vesicle membranes, nanotubes, and spherical micelles. The PAA block chains were partially ionized, leading to the negative zeta potential of AxS48O46S48Ax micelles in dilute aqueous solutions.

Raman spectroscopy and structural heterogeneity of carbonaceous material in Proterozoic organic-walled microfossils in the North China Craton

Raman spectroscopy is a minimally intrusive and minimally destructive technique that has played an important role in analyzing Precambrian carbonaceous microfossils and microstructures. Previous studies have shown that heterogeneities in structural order of carbonaceous material (CM) as revealed by Raman spectroscopy can be preserved in Proterozoic silicified cyanobacterial fossils. However, such heterogeneities have not been documented in Proterozoic eukaryotic microfossils preserved as carbonaceous compressions. In this study, we used Raman spectroscopy to investigate the structural characteristics of organic-walled microfossils, including eukaryotes preserved as carbonaceous compressions, from the late Paleoproterozoic Ruyang Group and the early Neoproterozoic (Tonian) Liulaobei Formation in the North China Craton. Raman geothermometers indicate that CM experienced low-grade metamorphism with apparent peak metamorphic temperatures of ~200 °C for both the Ruyang and Liulaobei microfossils. Heterogeneities in structural characteristics of CM in eukaryotic microfossils were found among different subcellular structures of Shuiyousphaeridium macroreticulatum and among different taxa from the same stratigraphic horizon. We suggest that these heterogeneities can be attributed to differences in precursor organic compounds; thus, the importance of organic precursors should be considered in CM Raman geothermometry studies, especially in environments where heating events occurred quickly. The Raman data presented here are also consistent with hypotheses that the Ruyang microfossils Dictyosphaera delicata and S. macroreticulatum are biologically conspecific taxa with their vesicle walls having similar CM Raman features, and that the Liulaobei microfossils Leiosphaeridia jacutica and L. tenuissima are distinct taxa despite their similarities in morphologies other than vesicle wall thickness. Although more data are needed to verify the consistency of interspecies, intraspecies, and intraspecimen variability, this study indicates that Raman spectroscopy may have the potential to provide an independent test of early eukaryote taxonomy, which has been traditionally based only on morphological features, and to reveal heterogeneities of CM of early eukaryotic organisms.

Vapor Transport and Deposition of Cu-Sn-Co-Ag Alloys in Vesicles in Mafic Volcanic Rocks

AbstractMetallic sublimates coated by sulfides and chlorides line the vesicle walls of mafic volcanic lava and bombs from Kīlauea, Vesuvius, Etna, and Stromboli. The metallic sublimates were morphologically and compositionally similar among the volcanoes. The highest concentrations of S and Cl occurred on the surface of the sublimates, while internally they had less than 1 wt % S and Cl in most cases, leading us to classify them as alloys. The major components of the alloys were Cu, Sn, Co, and Ag based on electron microprobe analyses and environmental scanning electron microscope element maps. Alloy element maps showed a covariance of Cu-Sn, while Co and Ag concentrations varied independently. Laser ablation-inductively coupled plasma-mass spectrometry analysis of matrix glass and melt inclusions in bombs from Stromboli showed appreciable amounts of Cu, Co, and Sn. We propose a model for the origin of the metallic grains, which involves syneruptive and posteruptive magma degassing and subsequent cooling of the basalt vesicles. During syneruptive vapor phase exsolution, volatile metals (Cu, Co, and Sn) partition into the vapor along with their ligands, S and Cl. The apparent oxygen fugacity (fO2) in these vapor bubbles is low because of the relative enrichment of the exsolved gas phase in H2 relative to H2O in silicate melts, due to the much higher diffusivity of the former in silicate melts. The high fH2 and low fO2 induces the precipitation of metal alloys from the vapor phase. Subsequently, the reducing environment in the vesicle dissipates as the cooling vapor oxidizes and as H2 diffuses away. Then, metal-rich sulfides (and chlorides) condense onto the outer surfaces of the metal alloy grains either due to a decrease in temperature or an increase in fO2. These alloys provide important insights into the partitioning of metals into a magmatic volatile phase at low pressure and high temperature.

Precisely Controlled Incorporation of Drug Nanoparticles in Polymer Vesicles by Amphiphilic Copolymer Tethers

In this paper, we describe the fabrication of nanoparticle (NP)-embedded nanovesicles by coassembly of diblock copolymer-tethered NPs and free diblock copolymers via the dissipative particle dynamics simulation technique. We use an improved quantitative model to characterize the angular and radial distributions of NPs within vesicle walls simultaneously. In a specific circumstance, the NPs can be localized in the central portion of the vesicle walls, which is in excellent agreement with the experimental work. On the basis of this model, we find that the distributions of the NPs can be well manipulated just by three physical quantities, which are easily controlled in the experiments. For instance, the radial distributions of the NPs can be precisely controlled by changing the grafted hydrophobic chain length and the tethered arm number affects the dispersity of the NPs in the angular direction of the vesicle walls. The results provide the experimentalists with a way to design carrier-assistant drug deliver...

Neutral and acid-adapted fatty acid vesicles of conjugated linoleic acid.

FAVs (fatty acid vesicles), originated from natural biomass and created available biointerface, have advantages of biocompatibility, low-cost, and easy self-assembly in aqueous solution due to their dynamic feature. However, there is no example of applying FAVs in contact with human body since they are inherently alkaline-adapted and pH windows for the FAV formation and application are very narrow and far away from the physiological pH range. In this work an attempt to turn the alkaline-adapted FAVs into neutral and acid-adapted ones was made by fabricating the amphiphile-hybrid vesicles of CLA (conjugated linoleic acid) with a typical cosmetic emulsifier SDS (sodium dodecylsulfate) and/or a co-emulsifier DA (dodecyl alcohol). pH windows for the SDS- and/or DA-hybrid FAV formation of CLA were judged by using dynamic light scattering criterion, and confirmed by small-angle X-ray scattering and room temperature transmission electron microscopy. The experimental results show that with the aid of H-bonding and ion-dipole forces among molecules of CLA, SDS and DA within the hybrid vesicle walls that were identified by Fourier transform infrared analysis, much wider pH windows of 2.5-11.7 for the hybrid FAVs were obtained by expansion from 8.0-9.0 for FAV of CLA alone, which was composition-dependent and made the hybrid FAVs become neutral and acid-adapted.

Membrane Nanotubes Increase the Robustness of Giant Vesicles.

Giant unilamellar vesicles (GUVs) provide a direct connection between the nano- and the microregime. On the one hand, these vesicles represent biomimetic compartments with linear dimensions of many micrometers. On the other hand, the vesicle walls are provided by single molecular bilayers that have a thickness of a few nanometers and respond sensitively to molecular interactions with small solutes, biopolymers, and nanoparticles. These nanoscopic responses are amplified by the GUVs and can then be studied on much larger scales. Therefore, GUVs are increasingly used as a versatile research tool for basic membrane science, bioengineering, and synthetic biology. Conventional GUVs have one major drawback, however: they have only a limited capability to cope with external perturbations such as osmotic inflation, adhesion, or micropipette aspiration that tend to rupture the membranes. In contrast, cell membranes tolerate the same kinds of mechanical perturbations without rupture because the latter membranes are coupled to reservoirs of membrane area. Here, we introduce GUVs with membrane nanotubes as model systems that include such area reservoirs. To demonstrate the increased robustness of these tubulated vesicles, we use micropipette aspiration and changes in the osmotic conditions applied to phospholipid membranes doped with the glycolipid GM1. A quantitative comparison between theory and experiment reveals that the response of the GUVs is governed by the membranes' spontaneous tension, a curvature-elastic material parameter that describes the bilayer asymmetry on the nanoscale. Because of their increased robustness, GUVs with nanotubes represent improved research tools for membrane science, in general, with potential applications as storage and delivery systems and as cell-like microcompartments in bioengineering, pharmacology, and synthetic biology.

Lipopolysaccharide Associates with Amyloid Plaques, Neurons and Oligodendrocytes in Alzheimer's Disease Brain: A Review.

This review proposes that lipopolysaccharide (LPS, found in the wall of all Gram-negative bacteria) could play a role in causing sporadic Alzheimer’s disease (AD). This is based in part upon recent studies showing that: Gram-negative E. coli bacteria can form extracellular amyloid; bacterial-encoded 16S rRNA is present in all human brains with over 70% being Gram-negative bacteria; ultrastructural analyses have shown microbes in erythrocytes of AD patients; blood LPS levels in AD patients are 3-fold the levels in control; LPS combined with focal cerebral ischemia and hypoxia produced amyloid-like plaques and myelin injury in adult rat cortex. Moreover, Gram-negative bacterial LPS was found in aging control and AD brains, though LPS levels were much higher in AD brains. In addition, LPS co-localized with amyloid plaques, peri-vascular amyloid, neurons, and oligodendrocytes in AD brains. Based upon the postulate LPS caused oligodendrocyte injury, degraded Myelin Basic Protein (dMBP) levels were found to be much higher in AD compared to control brains. Immunofluorescence showed that the dMBP co-localized with β amyloid (Aβ) and LPS in amyloid plaques in AD brain, and dMBP and other myelin molecules were found in the walls of vesicles in periventricular White Matter (WM). These data led to the hypothesis that LPS acts on leukocyte and microglial TLR4-CD14/TLR2 receptors to produce NFkB mediated increases of cytokines which increase Aβ levels, damage oligodendrocytes and produce myelin injury found in AD brain. Since Aβ1–42 is also an agonist for TLR4 receptors, this could produce a vicious cycle that accounts for the relentless progression of AD. Thus, LPS, the TLR4 receptor complex, and Gram-negative bacteria might be treatment or prevention targets for sporadic AD.

Intravesicular Phosphatase PHOSPHO1 Function in Enamel Mineralization and Prism Formation.

The transport of mineral ions from the enamel organ-associated blood vessels to the developing enamel crystals involves complex cargo packaging and carriage mechanisms across several cell layers, including the ameloblast layer and the stratum intermedium. Previous studies have established PHOSPHO1 as a matrix vesicle membrane-associated phosphatase that interacts with matrix vesicles molecules phosphoethanolamine and phosphocholine to initiate apatite crystal formation inside of matrix vesicles in bone. In the present study, we sought to determine the function of Phospho1 during amelogenesis. PHOSPHO1 protein localization during amelogenesis was verified using immunohistochemistry, with positive signals in the enamel layer, ameloblast Tomes' processes, and in the walls of ameloblast secretory vesicles. These ameloblast secretory vesicle walls were also labeled for amelogenin and the exosomal protein marker HSP70 using immunohistochemistry. Furthermore, PHOSPHO1 presence in the enamel organ was confirmed by Western blot. Phospho1−/− mice lacked sharp incisal tips, featured a significant 25% increase in total enamel volume, and demonstrated a significant 2-fold reduction in silver grain density of von Kossa stained ground sections indicative of reduced mineralization in the enamel layer when compared to wild-type mice (p < 0.001). Scanning electron micrographs of Phospho1−/− mouse enamel revealed a loss of the prominent enamel prism “picket fence” structure, a loss of parallel crystal organization within prisms, and a 1.56-fold increase in enamel prism width (p < 0.0001). Finally, EDS elemental analysis demonstrated a significant decrease in phosphate incorporation in the enamel layer when compared to controls (p < 0.05). Together, these data establish that the matrix vesicle membrane-associated phosphatase PHOSPHO1 is essential for physiological enamel mineralization. Our findings also suggest that intracellular ameloblast secretory vesicles have unexpected compositional similarities with the extracellular matrix vesicles of bone, dentin, and cementum in terms of vesicle membrane composition and intravesicular ion assembly.

The role of homocysteine in seminal vesicles remodeling in rat

Elevated plasma homocysteine (Hcy) levels have been associated with several tissue injuries including heart and liver fibrosis. In these diseases, hyperhomocysteinemia (Hhcy) plays a major role in modulating the alteration of the balance between matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMPs), leading to the pathological accumulation of extracellular matrix (ECM) proteins. Since the effect of Hhcy on ECM of seminal vesicle was not studied, the aim of our research was to check if Hcy can induce a remodeling within seminal vesicles ECM. The study was conducted in 22 adult male Wistar rats. The rats were divided into two groups: a control group, which received standard diet and tap water; the treated group received the same diet and water supplemented with solution of L-methionine (200 mg/kg b.w./day) for 6 months. Plasma homocysteine concentration was measured. Histological changes were observed with light microscope. The presence of collagen I and III and metalloproteinases (2, 3, 7 and 9) in the seminal vesicles was examined using immunohistochemistry and Western blotting. Plasma Hcy levels increased significantly after methionine treatment and interfered significantly with body weight in treated rats. The content of fibrillar collagens (I and III) in the wall of seminal vesicles was elevated in hyperhomocysteinemic rats. Moreover, we found that hyperhomocysteinemia increased the expression of MMP-2, -3, -7 and -9 in seminal vesicles of experimental rats. Increased plasma concentration of Hcy accompanied by the accumulation of collagen and upregulation of MMPs in rat seminal vesicles might contribute to the remodeling of seminal vesicles.

Secondary self-assembly behaviors of PEO-b-PtBA-b-PS triblock terpolymers in solution

A series of PEO45-b-PtBA53-b-PS x (x = 42, 84, 165) triblock terpolymers were synthesized by the atom transfer radical polymerization and characterized by size exclusion chromatography and 1H NMR. Their self-assemblies were conducted by a two-step hierarchical self-assembly method and a one-step dialysis method and the self-assembly behaviors were investigated. The morphologies, sizes, and size distributions of micelles produced by the self-assembly were determined by transmission electron microscopy and dynamic light scattering. The secondary self-assembled structure of PEO45-b-PtBA53-b-PS x obtained by the two-step hierarchical self-assembly could be controlled by tuning the length of PS block, the core forming block. The micelles were uniform with diameters of 20–25 nm and their size distributions, except for that of PEO45-b-PtBA53-b-PS165, were narrow with particle size distribution indexes ranging from 0.014 to 0.246. The one-step dialysis of the triblock terpolymers produced vesicular micelles with distinct vesicle walls that exhibited similar thicknesses. The vesicles did not show significant aggregation. The size distribution of PEO45-b-PtBA53-b-PS42 vesicle was the narrowest with a particle size distribution index value of 0.135. The PEO45-b-PtBA53-b-PS165 vesicles tended to overlap with each other.

Ultrastructural characterization of Pleistophora macrozoarcidis Nigerelli 1946 (Microsporidia) infecting the ocean pout Macrozoarces americanus (Perciformes, Zoarcidae) from the gulf of Maine, MA, USA.

Pleistophora macrozoarcidis a microsporidian parasite infecting the muscle tissue of the ocean pout Macrozoarces americanus collected from the Gulf of Maine of the Atlantic Ocean, MA, USA, was morphologically described on the basis of ultrastructural features. Infection was detected as opaque white or rusty brown lesions scattered throughout the musculature of the fish mainly in the region anterior to anus. Transmission electron microscopy showed that in individual parasitized muscle cells, the infection progresses within parasite formed vesicles which are in direct contact with muscle cell elements. The earliest observed parasitic stages are the globular multinucleated proliferative cells or plasmodia limited by a highly tortuous plasmalemma with intervesicular finger-like digitations projecting into the parasite cytoplasm. These cells divided through the invagination of the plasmalemma and the amorphous coat producing daughter-cells. Fine electron-dense secretion is deposited on the plasmalemma that causes its thickening which is a sign of commencement of the sporogonic phase. This phase is carried out by cytokinesis of the sporonts and results in the formation of sporoblasts and finally spores. Mature spore has a thin electron-dense exospore, a thick electron-lucent endospore, and the plasma membrane which encloses the spore contents. A single nucleus is centrally located with the posterior region containing a posterior vacuole. The majority of spores have 7-13 coils in 1-2 rows, and a small group of spores had about 23 coils forming two rows. Events of polar filament extrusion for penetration of uninfected cells were studied. The polaroplast membranes were expanded and occupy most of the length of the spore. The coils are dislocated from the sides of the spore to throughout the entire sporoplasm. The polar filament everts and extrudes through the polar cap with a sufficient force to pierce adjacent sporophorous vesicle walls. After eversion, the polar filament is referred to as a polar tubule, as it forms a tube through which the sporoplasm travels. It pierces anything in its path and deposits the sporoplasm at a new location to begin another infective cycle.