Induce Vesicle Formation Research Articles

Effects of interfacial molarity on salts inducing vesicle-to-micelle transitions in acyl taurines

Specific ion effects (SIEs) are crucial in engineering, chemistry and biology. N-acyl taurine (NAT) exists naturally in organisms and may have various physiological functions. However, compared with other acyl amino acid-based surfactants bearing carboxylate headgroups, the SIEs on NATs have received little research. Here, sodium lauroyl taurate (SLT) and sodium methyl lauroyl taurate (SMLT) bearing secondary and tertiary amides, respectively, were synthesized by a green method. The interfacial molarities of water, amides and sulfonate groups in SLT and SMLT aggregates were estimated simultaneously in the presence of tetraalkylammonium cations (TAA+) of different chain lengths. With increasing salt concentration, the interfacial water molarity increased, whereas the interfacial amide molarity decreased in all cases. However, at a fixed salt concentration, the interfacial water molarity increased with the hydrophobicity of cations, while the interfacial amide bond molarity followed the reverse order. The combined TEM and DLS results show that the majority of SLT and SMLT molecules formed vesicles spontaneously in the absence of salts, and some of these vesicles turned into micelles with TAA+ addition. Tertiary amides of SMLT may also absorb protons at the interface and interact with each other by hydrogen bonding. Such hydrogen bonds facilitate the tight packing of surfactant molecules and induce vesicle formation, just like the intermolecular amide-amide hydrogen bonds between SLT. Added TAA+ cleaves the hydrogen bonds between NAT and induces vesicle-to-micelle transitions. This hypothesis is supported by CT results showing that vesicle-to-micelle transitions were accompanied by decreases in interfacial amide molarity.

Vesicle formation between single-chained cationic surfactants and ribo-oligonucleotides

Abstract Recently, we reported that deoxyribo-oligonucleotides could induce single chained cationic surfactant aggregation to form vesicles. In this paper, we will present that ribo-oligonucleotides can also induce vesicle formation, and compared with deoxyribo-oligonucleotides, ribo-oligonucleotides exhibit a higher inductive efficiency.

Cu2+-Induced Vesicle Formation

A Cu2+-induced vesicle phase was prepared from a mixture of 3-aminopropylmethyltrisiloxane and CuCl2 or Cu(NO3)2 in aqueous solutions. Cu2+ coordinated with 3-aminopropylmethyltrisiloxane resulting in the formation of molecular bilayers, because Cu2+ can firmly bind to the amine groups of 3-aminopropylmethyltrisiloxane which reduced the area of the head-group. In this system, no counterions in aqueous solution exist because of the Cu2+-ligand coordination, and the bilayer membranes are not shielded by salts. The vesicle formation of 3-aminopropylmethyltrisiloxane induced by Cu2+ ions was determined by transmission electron microscopy (TEM) images, dynamic light scattering (DLS) measurements, and x-ray diffraction (XRD).

Dynamics of a laterally evolving community of ribozyme-like agents as studied with a rule-based computing system.

The very early forms of life probably comprised ribozyme-like agents that were able to catalyze reactions and serve as templates for their own replication. The early evolution has also been suggested to occur mainly horizontally between proto-cells or inorganic compartments rather than vertically from parent cell to their dividing siblings. In order to study the evolutionary dynamics of such a community a rule-based computing system entitled as PrimordialEvo was developed. The system simulates a three dimensional matrix of compartments in which replicators, resource collectors and various other actors thrive. Horizontal movement between compartments may be due to genetically induced vesicle formation or random drift. Analysis of the simulation experiments suggests that active sharing of innovations between compartments is important for the overall reproductive success of life. The capability of natural selection to favor genes in the system was also tested, and, for example, the frequency of anti-parasites was observed to increase when parasites were allowed to emerge.

The Open Reading Frame 3a Protein of Severe Acute Respiratory Syndrome-Associated Coronavirus Promotes Membrane Rearrangement and Cell Death

The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.

Turnip Mosaic Virus RNA Replication Complex Vesicles Are Mobile, Align with Microfilaments, and Are Each Derived from a Single Viral Genome

Nicotiana benthamiana plants were agroinoculated with an infectious cDNA clone of Turnip mosaic virus (TuMV) that was engineered to express a fluorescent protein (green fluorescent protein [GFP] or mCherry) fused to the viral 6K2 protein known to induce vesicle formation. Cytoplasmic fluorescent discrete protein structures were observed in infected cells, corresponding to the vesicles containing the viral RNA replication complex. The vesicles were motile and aligned with microfilaments. Intracellular movement of the vesicles was inhibited when cells were infiltrated with latrunculin B, an inhibitor of microfilament polymerization. It was also observed that viral accumulation in the presence of this drug was reduced. These data indicate that microfilaments are used for vesicle movement and are necessary for virus production. Biogenesis of the vesicles was further investigated by infecting cells with two recombinant TuMV strains: one expressed 6K2GFP and the other expressed 6K2mCherry. Green- and red-only vesicles were observed within the same cell, suggesting that each vesicle originated from a single viral genome. There were also vesicles that exhibited sectors of green, red, or yellow fluorescence, an indication that fusion among individual vesicles is possible. Protoplasts derived from TuMV-infected N. benthamiana leaves were isolated. Using immunofluorescence staining and confocal microscopy, viral RNA synthesis sites were visualized as punctate structures distributed throughout the cytoplasm. The viral proteins VPg-Pro, RNA-dependent RNA polymerase, and cytoplasmic inclusion protein (helicase) and host translation factors were found to be associated with these structures. A single-genome origin and presence of protein synthetic machinery components suggest that translation of viral RNA is taking place within the vesicle.

Vesicle Formation and Endocytosis: Function, Machinery, Mechanisms, and Modeling

Vesicle formation provides a means of cellular entry for extracellular substances and for recycling of membrane constituents. Mechanisms governing the two primary endocytic pathways (i.e., caveolae- and clathrin-mediated endocytosis, as well as newly emerging vesicular pathways) have become the focus of intense investigation to improve our understanding of nutrient, hormone, and drug delivery, as well as opportunistic invasion of pathogens. In this review of endocytosis, we broadly discuss the structural and signaling proteins that compose the molecular machinery governing endocytic vesicle formation (budding, invagination, and fission from the membrane), with some regard for the specificity observed in certain cell types and species. Important biochemical functions of endocytosis and diseases caused by their disruption also are discussed, along with the structures of key components of endocytic pathways and their known mechanistic contributions. The mechanisms by which principal components of the endocytic machinery are recruited to the plasma membrane, where they interact to induce vesicle formation, are discussed, together with computational approaches used to simulate simplified versions of endocytosis with the hope of clarifying aspects of vesicle formation that may be difficult to determine experimentally. Finally, we pose several unanswered questions intended to stimulate further research interest in the cell biology and modeling of endocytosis.

Facilitation effect of oligonucleotide on vesicle formation from single‐chained cationic surfactant—Dependences of oligonucleotide sequence and size and surfactant structure

AbstractThe interaction between DNA and surfactant has both biological and technological significances. Recently, we reported for the first time that oligo d(C)25 can induce single‐chained cationic surfactant molecules to aggregate into vesicles. In this article, we studied systematically the formation of vesicles from traditional single‐chained cationic surfactant molecules in the presence of a series of oligonucleotides and found that the facilitation efficiency of oligonucleotide on vesicle formation depends on its size and base composition. Oligo d(T)n cannot induce vesicle formation, whereas the other oligonucleotides can. Moreover, the oligonucleotide with a bigger size or with a hairpin structure favors vesicle formation more, and the increases in the size of the head group and/or the length of the alkyl group of surfactant decrease the facilitation efficiency of oligonucleotide. Since so far, there is very limited report about the vesicle formation in DNA/single‐chained cationic surfactant solution, this study could be expected to increase the efficiency and applicability for DNA/amphiphile system. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 434–449, 2009

Inhibition of apoptosis by Heliothis virescens ascovirus (HvAV-3e): characterization of orf28 with structural similarity to inhibitor of apoptosis proteins

Ascoviruses (AVs) induce a unique pathology in their insect host cells causing cleavage of the cells into virion-containing vesicles. The mechanism by which AVs induce vesicle formation is poorly understood. It is postulated that the virus initially induces apoptosis leading to cell fragmentation. The apoptotic bodies are however, rescued by the virus to form the vesicles. Here we show that Heliothis virescens AV (HvAV-3e) is able to inhibit chemically induced apoptosis from around 16 h after infection. Analysis of the genome of the virus indicated the presence of a putative inhibitor of apoptosis (orf28) gene that encodes a protein with an imperfect baculovirus inhibitor of apoptosis repeat (BIR) and a RING domain. Transiently expressed orf28 did not inhibit chemically induced apoptosis suggesting that the protein may not serve as an inhibitor of apoptosis. Nevertheless, RNA interference studies revealed that the gene is probably essential for virus pathology and replication.

Al3+-induced vesicle formation

Aluminium laurate [Al(OOCC11H23)3] was synthesized as a surfactant, which can dissolve in micellar solution of a zwitterionic surfactant, tetradecycldimethylamine oxide (C14DMAO). The phase behavior of the mixtures of Al(OOCC11H23)3 and C14DMAO in water was studied and birefringent Lα-phase was observed. The birefringent Lα-phase consists of vesicles that were demonstrated by Polarizer and Transmission Electron Microscope (TEM) micrographs. Al3+-coordinated vesicles could be used as templating-precursor, providing a vesicle-route for preparation of inorganic nanoscale particles.

Atg19 Mediates a Dual Interaction Cargo Sorting Mechanism in Selective Autophagy

Autophagy is a catabolic membrane-trafficking mechanism conserved in all eukaryotic cells. In addition to the nonselective transport of bulk cytosol, autophagy is responsible for efficient delivery of the vacuolar enzyme Ape1 precursor (prApe1) in the budding yeast Saccharomyces cerevisiae, suggesting the presence of a prApe1 sorting machinery. Sequential interactions between Atg19-Atg11 and Atg19-Atg8 pairs are thought responsible for targeting prApe1 to the vesicle formation site, the preautophagosomal structure (PAS), and loading it into transport vesicles, respectively. However, the different patterns of prApe1 transport defect seen in the atg11Delta and atg19Delta strains seem to be incompatible with this model. Here we report that prApe1 could not be targeted to the PAS and failed to be delivered into the vacuole in atg8Delta atg11Delta double knockout cells regardless of the nutrient conditions. We postulate that Atg19 mediates a dual interaction prApe1-sorting mechanism through independent, instead of sequential, interactions with Atg11 and Atg8. In addition, to efficiently deliver prApe1 to the vacuole, a proper interaction between Atg11 and Atg9 is indispensable. We speculate that Atg11 may elicit a cargo-loading signal and induce Atg9 shuttling to a specific PAS site, where Atg9 relays the signal and recruits other Atg proteins to induce vesicle formation.

A role for BARS at the fission step of COPI vesicle formation from Golgi membrane

The core complex of Coat Protein I (COPI), known as coatomer, is sufficient to induce coated vesicular-like structures from liposomal membrane. In the context of biological Golgi membrane, both palmitoyl-coenzyme A (p-coA) and ARFGAP1, a GTPase-activating protein (GAP) for ADP-Ribosylation Factor 1, also participate in vesicle formation, but how their roles may be linked remains unknown. Moreover, whether COPI vesicle formation from Golgi membrane requires additional factors also remains unclear. We now show that Brefeldin-A ADP-Ribosylated Substrate (BARS) plays a critical role in the fission step of COPI vesicle formation from Golgi membrane. This role of BARS requires its interaction with ARFGAP1, which is in turn regulated oppositely by p-coA and nicotinamide adenine dinucleotide, which act as cofactors of BARS. Our findings not only identify a new factor needed for COPI vesicle formation from Golgi membrane but also reveal a surprising mechanism by which the roles of p-coA and GAP are linked in this process.

Metal ions induced vesicle formation of single-chained hydrocarbon surfactants with coordinated headgroups

The surfactant of N-dodecyliminodipropionate disodium salt has been synthesized, and structure has been well characterized. The properties in aqueous solution have been studied by potentiometric titration, surface tension, transmission electron microscopy (TEM) and ultra-violet (UV) spectra. It was found that N-dodecyliminodipropionate disodium could exist in four species (e. g. cation, zwitterion, monoanion, dianion) in aqueous solution depending on pH, and relative distribution of these ionic species as a function of pH was obtained. The critical micelle concentration (CMC), determined from the breakpoint of surface tension at different concentrations, is 4. 16×104 mol/L, and the surface tension at CMC is 30 mN/m. It was found that the self-aggregate structures in aqueous solution, transformed from micelles to vesicles after the Cu(II) added. The experimental results showed that coordination between the iminodipropionate group and Cu(II) resulted to vesicles formation.

Zn2+-Induced Vesicle Formation

Zn2+-induced vesicle formation has been studied for the first time in aqueous mixtures of tetradecyldimethylamine oxide (C14DMAO) and zinc 2,2-dihydroperfluorooctanoate [Zn(C6F13CH2COO)2]. The charged vesicle phase without any cosurfactants was prepared in the aqueous mixtures. The charged vesicle phase has interesting rheological properties. This ionically charged vesicle phase is not shielded by excess salts because of salt-free aqueous solutions. Such a vesicle phase is important for many applications where cosurfactant is not used. A cationic/anionic surfactant C14DMAOH+ -OOCCH2C6F13 system could be produced from C14DMAO/Zn(C6F13CH2COO)2 mixtures because the zwiterionic surfactant C14DMAO can be charged by the H+ released from H2S to a cationic surfactant and Zn2+ is precipitated. After ZnS particles are removed from the cationic/anionic surfactant solutions, the finally mixed sample does not contain excess salts as do other studied cationic/anionic surfactant systems. The sample is a birefringent Lα-...

Freeze-fracture transmission electron microscopy studies on the self-assemblies of amphiphilic solutions

Self-assemblies of amphiphiles in solutions were investigated by using freeze-fracture transmission electron microscopy (FF-TEM). Especially, vesicles were characterized by FF-TEM and the transition of self-assemblies was determined. The stacked lamellar Lα-phase was prepared without shear forces by a chemical reaction. The stacked lamellar Lα-phase can be transformed into multilamellar vesicles by the shearing forces that occur when the stacked lamellar Lα-phase sample is turned upside down a few times. The multilamellar vesicles can also be transformed into unilamellar vesicles by high shearing forces. These transitions were demonstrated by FF-TEM measurements. Zn2+-induced vesicle formation in the single-chain surfactant solutions was first achieved.

Influence of Shear on Lyotropic Lamellar Phases with Different Membrane Defects

The influence of shear on lyotropic lamellar phases in the system sodium dodecyl sulfate (SDS)/decanol/water has been studied using small angle neutron and light scattering (SANS, SALS), birefringence and rheology. Eight different samples with a constant water content of 67.4%, but different surfactant-cosurfactant ratio were studied. Static SANS measurements showed that replacing of SDS with decanol leads to a transition from a defective lamellar phase, characterized first by a ribbon like structure and then by a pore like structure, to a classical lamellar phase. An orientation diagram was obtained from SANS, SALS and birefringence measurements under shear. For samples with low decanol content, shear flow leads to an alignment of lamellae but in addition to previous studies, we found two reorientations, from a parallel (at low shear rates) to a perpendicular alignment of the lamellae (with respect to the walls of the shear cell) and to a parallel alignment again at the highest shear rates available. At intermediate decanol content, a shear induced formation of multilamellar vesicles was observed in a certain shear rate region. Samples with classical lamellar structure at high decanol content exhibited no shear induced vesicle formation.

Expression of the MAL Gene in the Thyroid: the MAL Proteolipid, a Component of Glycolipid-Enriched Membranes, Is Apically Distributed in Thyroid Follicles

The MAL proteolipid, an integral membrane protein expressed in T lymphocytes, polarized epithelial MDCK cells, and myelin-forming cells, has been identified as a component of internal glycolipid-enriched membrane (GEM) microdomains. On the basis of its ability to induce vesicle formation by ectopic expression, MAL has been recently proposed as a component of the machinery for GEM vesiculation. Taking into account the proposed role of GEMs in polarized transport, we have investigated the expression of the MAL gene in thyroid cells. Interestingly, MAL messenger RNA species were detected in the human thyroid, whereas they were undetectable in other endocrine glands tested. Moreover, epithelial FRT cells, a polarized rat cell line of thyroid origin, also expressed MAL transcripts. Immunohistochemical analysis of thyroid follicles, with a newly developed anti-MAL monoclonal antibody, indicates that MAL distribution is restricted to the apical zone of thyroid epithelial cells. Biochemical analyses, using FRT cells, indicate exclusive residence of MAL in GEM microdomains, and these analyses allowed the identification of MAL as a major protein component of the GEM fraction in this cell line. Our results are consistent with a role for MAL as a component of GEM microdomains in thyroid epithelial cells.

Catabolism of the human erythrocyte C3b/C4b receptor (CR1, CD35) : vesiculation and/or proteolysis?

Human erythrocytes (E) react by exocytosis of membrane vesicles to various stresses including the fixation of the membrane attack complex of Complement. E from normal individuals loose a notable proportion of their initial number of surface CR1 molecules during the ageing process. An acquired decrease of CR1 on E also occurs in pathological conditions such as Systemic Lupus Erythematosus or AIDS. The present study investigated whether calcium ionophore A23187 (Ca-ion) induced vesicle formation of human E in vitro is responsible for a preferential loss of CR1 as well as whether CR1 molecules at the surface of Ca-ion treated E or vesicles are: (i) functional, (ii) native or protease degraded, or (iii) more clustered than CR1 on native E. A study of E from 137 normal individuals showed that a one-hour Ca-ion induced vesicle formation preferentially removed one third of E surface CR1. Kinetic experiments suggested that all surface CR1 could be removed from E upon longer incubation times. CR1 molecules on vesicles were still able to inhibit Complement activation, and were found in larger clusters than on native E. These data suggest that a significant part of surface CR1 molecules may be removed from E by vesicle formation during the life of E in normal individuals. This phenomenon could be exacerbated in pathological conditions.

Vesicle formation in electrolyte solutions of a new cationic siloxane surfactant

The addition of the salts NaX [X=F, Cl, Br, I, salicylate (Sal), dodecylsulfate (DS)] to 0.13 M (5 wt%) micellar, aqueous solutions of the novel, cationic siloxane surfactant (Me 3 SiO) 2 Si(Me)-(CH 2 ) 3 + NMe 2 (CH 2 ) 2 OHCl - (BisCl) results in spontaneous formation of uni- and multilamellar vesicles. This is the first report of vesicle formation by a siloxane surfactant. The sizes of the vesicles range from 10 nm to 10 μm, and they are stable for at least several weeks at room temperature. For the sodium halides, the relative concentrations of salts required to induce vesicle formation follow the anion trend I<Br<Cl

In vivo and in vitro characteristics of contagious ecthyma virus isolates: Host response mechanism

Three Vero cell culture-adapted contagious ecthyma virus (CEV) isolates were compared by plaque morphology, ability to induce vesicles in skin and in vivo growth curve characteristics by sampling sequentially experimental skin lesions produced in four sheep and one goat. Two of the isolates (CEV-29A and CEV-378) were from outbreaks of ecthyma in sheep and one (CEV-102) from a human case of orf. When replicating in Vero cells, the viruses exhibited similar growth parameters, but were distinguishable from each other on the basis of plaque morphology. In vivo latent periods for these isolates were 48 h (CEV-29A), 96 h (CEV-102), and 120 h (CEV-378). When isolates CEV-102 and CEV-29A were passaged into another sheep, they produced similar patterns of growth. Isolate CEV-102 produced the highest infectivity titer [1.4 × 10 9 plaque forming units (PFU) g −1], followed by CEV-29A (6.8 × 10 7 PFU g −1) and CEV-378 (2.5 × 10 7 PFU g −1). In addition, these viruses varied in their ability to induce vesicle formation. Virus was no longer detectable at the inoculation sites at 288 h post-infection (PI). We conclude that plaque morphology, ability to induce vesicle formation in the skin and growth curves in the skin can be considered as important criteria to differentiate CEV isolates. A comparison of the growth curves of CEV-378 in the skin of sheep and goats suggested differences in virus-host interaction between the two animal species. Since intravenous injection of 1 × 10 9 PFU of CEV failed to produce lesions in the sham-scarified skin of sheep, virus spread via the hematogenous route from one site to another appears unlikely. No virus-neutralizing antibody or interferons were found in serum samples or in skin homogenates collected between 0 and 24 days PI. Virus-neutralizing antibody was present in the circulation as late as 24 days PI. Lymphocytes collected from CEV-exposed sheep as early as 12 days PI responded specifically to stimulation with CEV antigen. As this was about the time when infectious virus disappeared from the sites, we assume that cell-associated immune mechanisms may play a larger role in virus clearance from skin lesions than virus-neutralizing antibody.