Low density lipoproteins bound to Schistosoma mansoni do not alter the rapid lateral diffusion or shedding of lipids in the outer surface membrane

1991 ◽  
Vol 99 (1) ◽  
pp. 167-173
Author(s):  
J.P. Caulfield ◽  
C.P. Chiang ◽  
P.W. Yacono ◽  
L.A. Smith ◽  
D.E. Golan
Keyword(s):  
Schistosoma Mansoni ◽  
Outer Membrane ◽  
De Novo ◽  
Acyl Chain ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Lateral Mobility ◽  
Ldl Binding

Schistosomula of Schistosoma mansoni bind human low density lipoproteins (LDL) in a concentration-dependent and saturable manner. The bound LDL could provide phospholipids and sterol to the worm, which cannot synthesize sterol de novo and lacks acyl chain-modifying capability. Here we have used three phospholipid analogues to explore the effect of LDL binding on the parasite's outer tegumental membrane, i.e. the outer of the two membranes that cover its surface syncytium. Fluorescein phosphatidylethanolamine (Fl-PE) and rhodamine phosphatidylethanolamine (Rh-PE) bound to the parasite in a saturable manner and, as shown by fluorescence microscopy, were confined to the surface. Fl-PE fluorescence was completely quenched by Trypan Blue and Fl-PE was lost from the surface following single exponential decay kinetics (t1/2 = 12 h), further suggesting that the probe was confined to the outer membrane. 1,1′-Dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanine perchlorate (DiI-C18(3); DiI) did not bind saturably and was seen in both the surface and the internal parasite membranes. Fluorescence photobleaching recovery was used to measure the lateral mobility of Fl-PE in the outer membrane. The lateral diffusion coefficient of Fl-PE was approximately 10(−7) cm2s-1. The fractional mobility of Fl-PE was 85% when measured using a laser beam of radius 1.8 microns and 45% using a beam of radius 4.3 microns. These measurements suggest that the outer membrane is composed of micron-scale liquid crystalline-phase lipid domains that lack significant amounts of transmembrane proteins. LDL binding to the parasite surface did not alter the lateral mobility of Fl-PE or the rate of loss of either Fl-PE or Rh-PE.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The lateral diffusion of lipid probes in the surface membrane of Schistosoma mansoni.

1986 ◽  
Vol 103 (3) ◽  
pp. 807-818 ◽  
Author(s):  
M Foley ◽  
A N MacGregor ◽  
J R Kusel ◽  
P B Garland ◽  
T Downie ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Fluorescence Recovery After Photobleaching ◽  
Surface Membrane ◽  
Biological Significance ◽  
Lateral Diffusion ◽  
Asymmetric Distribution ◽  
Normal Surface ◽  
Membrane Blebs ◽  
Fluorescent Lipids ◽  
Fluorescent Lipid Analogues

The technique of fluorescence recovery after photobleaching was used to measure the lateral diffusion of fluorescent lipid analogues in the surface membrane of Schistosoma mansoni. Our data reveal that although some lipids could diffuse freely others exhibited restricted lateral diffusion. Quenching of lipid fluorescence by a non-permeant quencher, trypan blue, showed that there was an asymmetric distribution of lipids across the double bilayer of mature parasites. Those lipids that diffused freely were found to reside mainly in the external monolayer of the outer membrane whereas lipids with restricted lateral diffusion were located mainly in one or more of the monolayers beneath the external monolayer. Formation of surface membrane blebs allowed us to measure the lateral diffusion of lipids in the membrane without the influence of underlying cytoskeletal structures. The restricted diffusion found on the normal surface membrane of mature parasites was found to be released in membrane blebs. Quenching of fluorescent lipids on blebs indicated that all probes were present almost entirely in the external monolayer. Juvenile worms exhibited lower lateral diffusion coefficients than mature parasites: in addition, the lipids partitioned into the external monolayer. The results are discussed in terms of membrane organization, cytoskeletal contacts, and biological significance.

Distribution and biophysical properties of fluorescent lipids on the surface of adult Schistosoma mansoni

Parasitology ◽  
1996 ◽  
Vol 113 (2) ◽  
pp. 137-143 ◽  
Author(s):  
C. A. Redman ◽  
J. R. Kusel
Keyword(s):  
Schistosoma Mansoni ◽  
Outer Membrane ◽  
Adult Male ◽  
Surface Membrane ◽  
Fluorescent Microscopy ◽  
Biophysical Properties ◽  
Fluorescent Lipids ◽  
Pass Through ◽  
Lipid Compounds ◽  
Outer Monolayer

SUMMARYThe properties of 4 fluorescent lipid compounds in the surface membrane of adult male Schistosoma mansoni worms were examined by fluorescent microscopy and fluorescent recovery after photobleaching (FRAP). The data suggest that the probes N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl) sphingosine (BODIPY FL ceramide) and PKH2 pass through the outer membrane and enter structures in or below the membrane. In contrast 5-(N-octadecanoyl)aminofluorescein (AF18) and N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl) sphingosylphosphocholine (BODIPY FL sphingomyelin) insert into the outer monolayer. The DL values of these latter 2 compounds, 8·83 ± 2·35 × 10−9 cm2 s−1 and 2·76 ± 0·53 × 10−9cm2 s−1, respectively, suggest that they enter different domains. Furthermore, it was observed that both BODIPY FL ceramide and BODIPY FL sphingomyelin entered particular structures in or under the surface membrane. The possible nature of these particles is discussed.

Dynamic structure of the lower density lipoproteins. II. Deuterium NMR studies of the monolayer of very low and low density lipoproteins

1990 ◽  
Vol 68 (1) ◽  
pp. 189-198 ◽  
Author(s):  
Ravinder S. Chana ◽  
W. Dale Treleaven ◽  
Yashpal I. Parmar ◽  
Robert J. Cushley
Keyword(s):  
Acyl Chain ◽  
Dynamic Structure ◽  
Low Density Lipoproteins ◽  
Deuterium Nmr ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Nmr Studies ◽  
Surface Domains ◽  
Egg Pc ◽  
Low Order

The order of phosphatidylcholine (PC) acyl chains in the surface monolayer of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) has been determined from 2H nuclear magnetic resonance order parameters, SCD, using selectively deuterated PC or palmitic acids. From the computer simulated line shapes, we find two distinct phospholipid domains within the amphiphilic monolayer of both VLDL and LDL. In the more ordered domain of LDL, SCD was ≈ 0.3 for the "plateau" chain region. The SCD values of VLDL particles are similar to those of LDL for the 5,6- and 11,12-positions, hence we suggest the organization of the more ordered region of VLDL and LDL are similar. The domain of low order in LDL comprises < 10% of the phospholipid molecules (we do not distinguish between PC and sphingomyelin), having approximately the same order (SCD < 0.1) as egg PC - sphingomyelin unilamellar vesicles. In VLDL, the domain of low order comprises between ≈ 10 and ≈ 20% of the phospholipid molecules and the entire acyl chain is in an essentially isotropic environment (SCD < 0.02). We prepared VLDL-sized microemulsions composed of egg PC, deuterated PC, and triolein to test whether the apoproteins were responsible for creating the two differently organized domains in VLDL and LDL. Surprisingly, these protein-free particles also showed two domains of different order at two temperatures. The high order region, however, is less ordered than in VLDL and LDL. We explain two surface domains of PC in terms of lipid organization and the unique interactions of lipids in the various lipoprotein particles.Key words: lipoproteins, deuterium NMR, phospholipid organization, microemulsions, surface diffusion.

scholarly journals Low Density Lipoprotein Binding and Uptake by Human and Rat Isletβ Cells*

Endocrinology ◽  
1997 ◽  
Vol 138 (10) ◽  
pp. 4064-4068 ◽  
Author(s):  
A. Y. Grupping ◽  
M. Cnop ◽  
C. F. H. Van Schravendijk ◽  
J. C. Hannaert ◽  
Th. J. C. Van Berkel ◽  
...  
Keyword(s):  
Binding Sites ◽  
Islet Cells ◽  
Density Lipoprotein ◽  
Low Density Lipoproteins ◽  
Human Islet ◽  
Low Density ◽  
Β Cells ◽  
Very Low Density Lipoproteins ◽  
Cell Functions ◽  
Ldl Binding

Abstract Abnormalities in lipoprotein metabolism are common in diabetes. It is unknown whether variations in form or concentration of lipoproteins influence the function of pancreatic β cells. This study investigates whether low density lipoproteins (LDL) exhibit specific interactions with islet β cells. Radioactively labeled LDL (125I-LDL) and fluorescently labeled LDL (DiI-LDL) were used as tracers. Rat islet cells express high affinity LDL binding sites (Kd = 9 nm), which are also recognized by very low density lipoproteins and which are down-regulated by LDL. Binding of LDL appears restricted to the β cells, as it was not detected on islet endocrine non-β cells. At 37 C, LDL is taken up and lysosomally degraded by islet β cells but not by islet non-β cells. Human islet cells were also found to present LDL binding, uptake, and degradation. Compared with rat islet cells, human islet cells exhibit 10-fold less binding sites (2.107vs. 2.108 per 103 cells) with a 2-fold lower Kd value (5 nm) and an equal sensitivity to LDL-induced down-regulation. In conclusion, human and rat islet β cells express LDL receptors that can internalize the lipoprotein. This pathway should be examined for its potential role in (dys)regulating pancreatic β cell functions.

scholarly journals Diffusion rates of cell surface antigens of mouse-human heterokaryons. II. Effect of membrane potential on lateral diffusion.

1977 ◽  
Vol 75 (2) ◽  
pp. 483-489 ◽  
Author(s):  
M Edidin ◽  
T Y Wei
Keyword(s):  
Membrane Potential ◽  
Cell Surface ◽  
Single Cell ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Surface Antigens ◽  
Lateral Mobility ◽  
Cell Surface Antigens ◽  
Common Effect ◽  
Diffusion Rates

The rate of appearance, in a population of mouse-human heterokaryons, of cells with intermixed mouse and human surface antigens may be used to estimate the rate of lateral diffusion of the antigens in a single cell. Most heterokaryons appear to restrict diffusion of their surface antigens. These restrictions are altered by exposing either heterokaryons or their parent cells to conditions that change cell surface membrane potential. Media containing unphysiological concentrations of potassium ion, drugs, affecting the Na+,K+ ATPase, or a channel-forming antibiotic, gramicidin, all affect lateral mobility of cell surface antigens in a manner consistent with a common effect on membrane potential.

The organization of cell surface membrane domains

1989 ◽  
Vol 47 ◽  
pp. 804-805
Author(s):  
Michael Edidin
Keyword(s):  
Cell Surface ◽  
Membrane Lipids ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Cell Types ◽  
Membrane Domains ◽  
Membrane Biology ◽  
Morphological Polarity ◽  
Discrete Domains ◽  
Membrane Components

Cell surface membranes are based on a fluid lipid bilayer and models of the membranes' organization have emphasised the possibilities for lateral motion of membrane lipids and proteins within the bilayer. Two recent trends in cell and membrane biology make us consider ways in which membrane organization works against its inherent fluidity, localizing both lipids and proteins into discrete domains. There is evidence for such domains, even in cells without obvious morphological polarity and organization [Table 1]. Cells that are morphologically polarised, for example epithelial cells, raise the issue of membrane domains in an accute form.The technique of fluorescence photobleaching and recovery, FPR, was developed to measure lateral diffusion of membrane components. It has also proven to be a powerful tool for the analysis of constraints to lateral mobility. FPR resolves several sorts of membrane domains, all on the micrometer scale, in several different cell types.

Superoxide anion-induced peroxidation of human low density lipoproteins (LDL). Influence of the pH

1993 ◽  
Vol 90 ◽  
pp. 917-930
Author(s):  
D Bonnefont-Rousselot ◽  
M Gardès-Albert ◽  
S Lepage ◽  
J Delattre ◽  
C Ferradini
Keyword(s):  
Superoxide Anion ◽  
Low Density Lipoproteins ◽  
Low Density
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