scholarly journals Structural transition of actin filament in a cell-sized water droplet with a phospholipid membrane

2006 ◽  
Vol 124 (10) ◽  
pp. 104903 ◽  
Author(s):  
M. Hase ◽  
K. Yoshikawa
Keyword(s):  
Actin Filament ◽  
Water Droplet ◽  
Structural Transition ◽  
Phospholipid Membrane ◽  
A Cell

Radiation Effects with a Model Lipid Membrane

1971 ◽  
Vol 49 (8) ◽  
pp. 1187-1196 ◽  
Author(s):  
A. Petkau
Keyword(s):  
Radiation Effects ◽  
Lipid Membrane ◽  
Protonmotive Force ◽  
X Rays ◽  
Phospholipid Membrane ◽  
Nernst Potential ◽  
Membrane Interfaces ◽  
A Cell ◽  
Collimated Beam

A cell is described that permits a model phospholipid membrane and the two adjacent aqueous compartments to be irradiated with a collimated beam of X-rays. During a 2 h irradiation a marked increase in [H+] in the aqueous phases is observed. A protonmotive force, given by the H+ Nernst potential, is generated when one compartment only is irradiated or when both compartments separated by a membrane made structurally asymmetric by the adsorption of alamethicin, are irradiated equally.The results of irradiations in N2O, N2, and O2 indicate that the membrane scavenges the superoxide O2−. The effect is discussed in terms of a clearing field that is derived from the potential at the membrane interfaces.

Actin and the coordination of protrusion, attachment and retraction in cell crawling

1996 ◽  
Vol 16 (5) ◽  
pp. 351-368 ◽  
Author(s):  
J. Victor Small ◽  
Kurt Anderson ◽  
Klemens Rottner
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Filament ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
The Other ◽  
Coordination Mechanism ◽  
Over Expression ◽  
Cell Crawling ◽  
Cell Front ◽  
A Cell

To crawl over a substrate a cell must first protrude in front, establish new attachments to the substrate and then retract its rear. Protrusion and retraction utilise different subcompartments of the actin cytoskeleton and operate by different mechanisms, one involving actin polymerization and the other myosin-based contraction. Using as examples the rapidly locomoting keratocyte and the slowly moving fibroblast we illustrate how over expression of one or the other actin subcompartments leads to the observed differences in motility. We also propose, that despite these differences there is a common coordination mechanism underlying the genesis of the actin cytoskeleton that involves the nucleation of actin filaments at the protruding cell front, in the lamellipodium, and the relocation of these filaments, via polymerization and flow, to the more posterior actin filament compartments.

scholarly journals Phase Separation on a Phospholipid Membrane Inducing a Characteristic Localization of DNA Accompanied by Its Structural Transition

2010 ◽  
Vol 1 (23) ◽  
pp. 3391-3395 ◽  
Author(s):  
Ayako Kato ◽  
Akihiko Tsuji ◽  
Miho Yanagisawa ◽  
Daisuke Saeki ◽  
Kazuhiko Juni ◽  
...  
Keyword(s):  
Phase Separation ◽  
Structural Transition ◽  
Phospholipid Membrane ◽  
Characteristic Localization

Apatite Layer with Serum Protein as a Suitable Scaffold for Growth of Osteoblast-Like Cell

2005 ◽  
Vol 284-286 ◽  
pp. 611-614
Author(s):  
Takashi Kizuki ◽  
Masataka Ohgaki ◽  
Kimihiro Yamashita ◽  
Yoshiyuki Yokogawa
Keyword(s):  
Tissue Engineering ◽  
Cell Adhesion ◽  
Serum Protein ◽  
Actin Filament ◽  
Apatite Layer ◽  
Engineering Technique ◽  
A Cell ◽  
Ceramic Hydroxyapatite ◽  
The Many ◽  
Surface Modified

Autograft, allograft, and biomaterials had been developed for bone regeneration. In recent year, a tissue engineering technique has been paid much attention for next generation implant. A problem of bone tissue engineering to be solved is a development of the substrate that is suitable for cell adhesion, proliferation, and differentiation. A biomimic scaffold for tissue culture was proposed, and then a cell response on the scaffold was estimated. The scaffold composed by a calcium deficient apatite with an adsorbed serum protein was formed on a ceramic hydroxyapatite (HAp) and surface-modified titanium by a soaking in cell-culture medium supplemented with fetal bovine serum. Excellent results on cell proliferation and cell adhesion were obtained only on osteoblast-like cells (MC3T3-E1). An actin filament in narrow filopodium of the spindle-shaped MC3T3-E1 cells on the ceramic HAp had a regular course. On the other hand, ends of the actin filament of the widely spread cells on the apatite layer with serum protein were scattering. It was suggested that the scattering of the actin end showed an existence of fibronectin, and then tight adhesion would be obtained by the many focal adhesion. Accordingly, the effectiveness of the biomimic scaffold containing serum protein on cell growth was confirmed.

Effect of Niacin on Mitochondria of Allium Cepa Root Cells

1967 ◽  
Vol 25 ◽  
pp. 78-79
Author(s):  
M. Arif Hayat
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Hydrogen Transfer ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Root Tips ◽  
Root Cells ◽  
Transfer Processes ◽  
Standard Procedures ◽  
A Cell ◽  
Critical Interest

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.

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.

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