Ultrastructural Morphology of Cationic Liposome/Dna Complexes for Gene Therapy: Correlation to Transfection Activity

1999 ◽  
Vol 5 (S2) ◽  
pp. 1108-1109
Author(s):  
Brigitte Sternberg ◽  
Keelung Hong ◽  
Weiwen Zheng ◽  
Demetrios Papahadjopoulos
Keyword(s):  
Lipid Bilayers ◽  
Freeze Fracture ◽  
Cationic Liposome ◽  
Mouse Serum ◽  
Active Structure ◽  
Dna Monolayers ◽  
Metastable Structures ◽  
Fracture Electron

Complexes formed during interaction of cationic liposomes with poly-nucleotides such as DNA (CLDC) display a variety of polymorphic and metastable structures. These include multilamellar structures of alternating lipid bilayers and DNA monolayers; fibrillar structures, among them spaghetti-liketubules (Figure 1), and map-pin-structures(Figure 2), and, finally, non-bilayer lipid arrangements, such as hexagonal (HII) (Figure 3) and cubic phases.In order to find out the “active” structure(s) in terms of transfection, we investigated the transfection activity both in vivoand in vitroof CLDC composed of the lipid DDAB (dimethyl-dioctadecylammonium bromide) and Choi (cholesterol) or DOPE (l,2-dioleoyl-sn-glycerol-3- phosphoethanolamine) as helper lipids. In parallel we studied their morphology by freeze-fracture electron microscopy.The in vivostudies were carried out in mice following i.v. injection and therefore the morphology of the CLDC was investigated in mouse serum.

Cationic Liposome-DNA Complexes: Polymorphism versus Transfection Activity

2000 ◽  
Vol 6 (S2) ◽  
pp. 854-855
Author(s):  
B. Sternberg-Papahadjopoulos ◽  
K. Hong ◽  
W. Zheng ◽  
D. Papahadjopoulos
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Freeze Fracture ◽  
Cationic Liposome ◽  
Specific Structure ◽  
Spherical Particles ◽  
Cubic Phase ◽  
Active Structure

Complexes formed during interaction of cationic liposomes with polynucleotides such as DNA (CLDC) self-assemble into a variety of polymorphic structures. They display bilayer (FIG. 1-5) and non-bilayer structures (FIG. 6). We have recorded bilayer structures such as spaghetti/meatball-type structures (FIG. I), map-pins (FIG. 2) spherical particles and invaginated liposomes (FIG. 3, 4) and oligolamellar structures (FIG. 5). The non-bilayer lipid arrangements include honeycombtype structure (Hn, FIG. 6) and cubic phase lipids.We have chosen mainly freeze-fracture electron microscopy (FIG. 1-3, 5,6) but also cryo-electron microscopy (FIG.4) for recording polymorphic structures, and for studying factors and conditions triggering the formation and stabilization of specific structure types. Furthermore, we took microscopically snapshots of the interaction of specific structure types with cultured cells. In order to find out the “active” structure in terms of transfection, we investigated the transfection activity both in vivo and in vitro of CLDC, and studied in parallel their morphology in serum as well as in cell medium.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

scholarly journals Coassembly of SecYEG and SecA Fully Restores the Properties of the Native Translocon

2018 ◽  
Vol 201 (1) ◽  
Author(s):  
Priya Bariya ◽  
Linda L. Randall
Keyword(s):  
Lipid Bilayers ◽  
Rate Constant ◽  
Apparent Rate Constant ◽  
Membrane Vesicles ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Secretory System ◽  
Rate Limiting

ABSTRACTIn all cells, a highly conserved channel transports proteins across membranes. InEscherichia coli, that channel is SecYEG. Many investigations of this protein complex have used purified SecYEG reconstituted into proteoliposomes. How faithfully do activities of reconstituted systems reflect the properties of SecYEG in the native membrane environment? We investigated by comparing threein vitrosystems: the native membrane environment of inner membrane vesicles and two methods of reconstitution. One method was the widely used reconstitution of SecYEG alone into lipid bilayers. The other was our method of coassembly of SecYEG with SecA, the ATPase of the translocase. For nine different precursor species we assessed parameters that characterize translocation: maximal amplitude of competent precursor translocated, coupling of energy to transfer, and apparent rate constant. In addition, we investigated translocation in the presence and absence of chaperone SecB. For all nine precursors, SecYEG coassembled with SecA was as active as SecYEG in native membrane for each of the parameters studied. Effects of SecB on transport of precursors faithfully mimicked observations madein vivo. From investigation of the nine different precursors, we conclude that the apparent rate constant, which reflects the step that limits the rate of translocation, is dependent on interactions with the translocon of portions of the precursors other than the leader. In addition, in some cases the rate-limiting step is altered by the presence of SecB. Candidates for the rate-limiting step that are consistent with our data are discussed.IMPORTANCEThis work presents a comprehensive quantification of the parameters of transport by the Sec general secretory system in the threein vitrosystems. The standard reconstitution used by most investigators can be enhanced to yield six times as many active translocons simply by adding SecA to SecYEG during reconstitution. This robust system faithfully reflects the properties of translocation in native membrane vesicles. We have expanded the number of precursors studied to nine. This has allowed us to conclude that the rate constant for translocation varies with precursor species.

scholarly journals Soluble Asialoglycoprotein Receptors Reflect the Apoptosis of Hepatocytes

2002 ◽  
Vol 11 (5) ◽  
pp. 407-415 ◽  
Author(s):  
Tetsuji Kakegawa ◽  
Hirohiko Ise ◽  
Nobuhiro Sugihara ◽  
Toshio Nikaido ◽  
Naoki Negishi ◽  
...  
Keyword(s):  
Cell Death ◽  
Liver Tissue ◽  
Liver Diseases ◽  
Culture Medium ◽  
Apoptotic Cell ◽  
Rabbit Serum ◽  
Mouse Serum ◽  
Apoptosis And Necrosis

Cell death is thought to take place through at least two distinct processes: apoptosis and necrosis. There is increasing evidence that dysregulation of the apoptotic program is involved in liver diseases. However, there is no method to simply evaluate apoptosis in the liver tissue at present. It has been reported that the expression of asialoglycoprotein receptors (AGPRs) increases with apoptosis, but there is no report until now that investigates the influence of soluble AGPRs on apoptosis of hepatocytes. Soluble AGPRs have been reported to be present in human serum under physiological conditions. In the present study, in order to investigate the correlation between apoptosis of hepatocytes and soluble AGPR, mouse soluble AGPRs were detected using SDS-PAGE and Western blot analysis was conducted using anti-extracellular mouse hepatic lectin-1 (Ex-MHL-1) antiserum (polyclonal rabbit serum). The mouse soluble AGPRs were present in culture medium and mouse serum when hepatocytes were damaged. The soluble AGPRs increased proportionately, as the number of dead hepatocytes increased. In addition, soluble AGPRs existed more when apoptotic cell death was observed in in vitro and in vivo than when necrotic cell death was observed. The extracellular moiety of MHL-1 exists in the culture medium and mouse serum as a soluble AGPR, but the detailed mechanism of releasing soluble AGPR from hepatocytes has not been revealed yet. We described the first evidence for the relation between quantity of soluble AGPRs with two kinds of cell death: necrosis and apoptosis. Based on the results of our study, soluble AGPRs might become a new marker of apoptosis in the liver tissue and be useful for clinical diagnosis and treatment for liver diseases.

Efficacy of cationic liposome-mediated gene transfer to mesangial cells in vitro and in vivo

2001 ◽  
Vol 79 (4) ◽  
pp. 184-189 ◽  
Author(s):  
Henning Madry ◽  
Regina Reszka ◽  
Jürgen Bohlender ◽  
Jürgen Wagner
Keyword(s):  
Gene Transfer ◽  
Mesangial Cells ◽  
Cationic Liposome

scholarly journals The C-terminus of cytochrome b5 confers endoplasmic reticulum specificity by preventing spontaneous insertion into membranes

2007 ◽  
Vol 401 (3) ◽  
pp. 701-709 ◽  
Author(s):  
Matthew P. A. Henderson ◽  
Yeen Ting Hwang ◽  
John M. Dyer ◽  
Robert T. Mullen ◽  
David W. Andrews
Keyword(s):  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Lipid Bilayers ◽  
Fusion Proteins ◽  
Molecular Mechanisms ◽  
Cytochrome B5 ◽  
Terminal Sequence ◽  
C Terminus

The molecular mechanisms that determine the correct subcellular localization of proteins targeted to membranes by tail-anchor sequences are poorly defined. Previously, we showed that two isoforms of the tung oil tree [Vernicia (Aleurites) fordii] tail-anchored Cb5 (cytochrome b5) target specifically to ER (endoplasmic reticulum) membranes both in vivo and in vitro [Hwang, Pelitire, Henderson, Andrews, Dyer and Mullen (2004) Plant Cell 16, 3002–3019]. In the present study, we examine the targeting of various tung Cb5 fusion proteins and truncation mutants to purified intracellular membranes in vitro in order to assess the importance of the charged CTS (C-terminal sequence) in targeting to specific membranes. Removal of the CTS from tung Cb5 proteins resulted in efficient binding to both ER and mitochondria. Results from organelle competition, liposome-binding and membrane proteolysis experiments demonstrated that removal of the CTS results in spontaneous insertion of tung Cb5 proteins into lipid bilayers. Our results indicate that the CTSs from plant Cb5 proteins provide ER specificity by preventing spontaneous insertion into incorrect subcellular membranes.

Comparative pathogenicity of auxotrophic mutants of Candida albicans

1984 ◽  
Vol 30 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Marcia Manning ◽  
Christina B. Snoddy ◽  
Robert. A. Fromtling
Keyword(s):  
Candida Albicans ◽  
Parent Strain ◽  
Antifungal Drugs ◽  
Mouse Serum ◽  
Temperature Sensitive ◽  
Auxotrophic Mutants ◽  
Growth Requirements ◽  
Induced Mutant

An induced mutant of Candida albicans with greatly decreased virulence for mice is described. The mutant was one of five auxotrophic mutants obtained by ultraviolet irradiation of a clinical isolate (strain MY 1044). The five mutants included two methionine auxotrophs, one methionine–cysteine auxotroph, one temperature-sensitive serine auxotroph, and one auxotroph with unknown growth requirements. Each of the mutants produced normal mycelium and had a normal profile of susceptibility to four antifungal drugs. The virulence of each mutant was compared with the parent strain by LD50 determination in mice. Four of the five auxotrophs exhibited LD50's that were not significantly different from the parent strain (mean LD50 = 7.5 × 105 cells). However, the temperature-sensitive serine auxotroph was significantly less virulent than the parent strain (LD50 > 107 cells), even though it grew well in vivo and in mouse serum at 37 °C in vitro. Use of this mutant in conjunction with its "isogenic" parent should help to elucidate true virulence factors in C. albicans.

Characteristics of eosinophilic inclusions within Schistosoma japonicum eggs

Parasitology ◽  
1999 ◽  
Vol 118 (3) ◽  
pp. 269-274 ◽  
Author(s):  
M. HIRATA ◽  
T. NAKASHIMA ◽  
T. FUKUMA
Keyword(s):  
Schistosoma Japonicum ◽  
Granuloma Formation ◽  
Mouse Serum ◽  
Exact Nature ◽  
Factors Associated ◽  
Splenic Cells ◽  
Eosinophilic Inclusions ◽  
Egg Antigen

Although eosinophilic bar- or droplet-like inclusions are frequently detectable inside eggs deposited in the livers of Schistosoma japonicum-infected animals, little is known of their exact nature. In the livers of mice implanted with freshly laid eggs, inclusion-positive eggs were found in 28·7 and 46·2% of deposited eggs at 2 and 4 weeks, respectively, after implantation, but in 4·3% at 5 weeks when most of the eggs had already degenerated. When the extent of granuloma formation was investigated, granulomas around inclusion-positive eggs were smaller than those around negative eggs. Host factors associated with the formation of inclusion were sought using in vivo and in vitro studies. Following the administration of anti-egg antigen serum into egg-implanted mice, no increase in occurrence of inclusion-positive eggs was seen. In a co-culture of mature eggs with infected rabbit or mouse serum, inclusions were rarely found. In contrast, they were found in 17·9% of eggs in the presence of splenic cells. The present study is the first to show that there is decreased granuloma formation in the presence of eosinophilic inclusions inside eggs and our in vitro study suggests that host cell–egg interaction is responsible for the formation of inclusions.

scholarly journals Additional In Vitro and In Vivo Evidence for SecA Functioning as Dimers in the Membrane: Dissociation into Monomers Is Not Essential for Protein Translocation in Escherichia coli

2007 ◽  
Vol 190 (4) ◽  
pp. 1413-1418 ◽  
Author(s):  
Hongyun Wang ◽  
Bing Na ◽  
Hsiuchin Yang ◽  
Phang C. Tai
Keyword(s):  
Escherichia Coli ◽  
Lipid Bilayers ◽  
Cytoplasmic Membrane ◽  
Protein Translocation ◽  
Secretory Proteins ◽  
Oligomeric State ◽  
Dependent Protein ◽  
Ts Mutant

ABSTRACT SecA is an essential component in the Sec-dependent protein translocation pathway and, together with ATP, provides the driving force for the transport of secretory proteins across the cytoplasmic membrane of Escherichia coli. Previous studies established that SecA undergoes monomer-dimer equilibrium in solution. However, the oligomeric state of functional SecA during the protein translocation process is controversial. In this study, we provide additional evidence that SecA functions as a dimer in the membrane by (i) demonstration of the capability of the presumably monomeric SecA derivative to be cross-linked as dimers in vitro and in vivo, (ii) complementation of the growth of a secA(Ts) mutant with another nonfunctional SecA or (iii) in vivo complementation and in vitro function of a genetically tandem SecA dimer that does not dissociate into monomers, and (iv) formation of similar ring-like structures by the tandem SecA dimer and SecA in the presence of lipid bilayers. We conclude that SecA functions as a dimer in the membrane and dissociation into monomers is not necessary during protein translocation.

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