The Adhesive Glycoprotein of the Orb Web of Argiope Aurantia (Araneae, Araneidae)

1992 ◽  
Vol 292 ◽  
Author(s):  
Edward K. Tillinghast ◽  
Mark A. Townley ◽  
Thomas N. Wight ◽  
Gerhard Uhlenbruck ◽  
Eveline Janssen
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Liquid Chromatography ◽  
Amino Acid Content ◽  
Apparent Molecular Weight ◽  
Gas Liquid Chromatography ◽  
The Core ◽  
Argiope Aurantia ◽  
Orb Web ◽  
Gland Type

AbstractA phosphorylated, glycoprotein preparation has been obtained from orb webs of the araneid spider Argiope aurantia. This preparation probably contains proteins from more than one gland type, but resolution of these proteins has not yet been achieved. Nevertheless, a major component appears to be the adhesive glycoprotein(s) from the adhesive spiral. A product of the aggregate glands, this glycoprotein(s) occurs as discrete nodules along the core fibers of the adhesive spiral, within the viscid, aqueous droplets.The glycoprotein preparation has a high apparent molecular weight (> 200 kDa) and is polydisperse. The only monosaccharide constituent identified by gas-liquid chromatography or in lectin studies is N-acetylgalactosamine and this is at least primarily O-linked to threonine. By electron microscopy, linear, unbranched and apparently flexible filaments are observed. Phosphorylated serine and threonine residues are present in the preparation and glycine, proline and threonine together account for about 57 mole % of the preparation's amino acid content. Thus, in some, but not all, respects, this glycoprotein preparation is reminiscent of a secretory mucin.

scholarly journals The cercarial glycocalyx of Schistosoma mansoni.

1985 ◽  
Vol 100 (5) ◽  
pp. 1423-1434 ◽  
Author(s):  
J C Samuelson ◽  
J P Caulfield
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Schistosoma Mansoni ◽  
High Molecular Weight ◽  
Membrane Surface ◽  
Periodate Oxidation ◽  
Apparent Molecular Weight ◽  
Ruthenium Red ◽  
Unit Membrane

Cercariae, the freshwater stage of Schistosoma mansoni infectious to man, are covered by a single unit membrane and an immunogenic glycocalyx. When cercariae penetrate the host skin, they transform to schistosomula by shedding tails, secreting mucous and enzymes, and forming microvilli over their surface. Here the loss of the glycocalyx from cercariae transforming in vitro was studied morphologically and biochemically. By scanning electron microscopy, the glycocalyx was a dense mesh composed of 15-30 nm fibrils that obscured spines on the cercarial surface. The glycocalyx was absent on organisms fixed without osmium and was partially lost when parasites aggregated in their own secretions before fixation. By transmission electron microscopy, a 1-2 microns thick mesh of 8-15-nm fibrils was seen on parasites incubated with anti-schistosomal antibodies or fixed in aldehydes containing tannic acid or ruthenium red. Cercariae transformed to schistosomula when tails were removed mechanically and parasites were incubated in saline. Within 5 min of transformation, organisms synchronously formed microvilli which elongated to 3-5 microns by 20 min and then were shed. However, considerable fibrillar material remained adherent to the double unit membrane surface of schistosomula. For biochemical labeling, parasites were treated with eserine sulfate, which blocked cercarial swimming, secretion, infectivity, and transformation to schistosomula. Material labeled by periodate oxidation and NaB3H4 was on the surface as shown by autoradiography and had an apparent molecular weight of greater than 10(6) by chromatography. Periodate-NaB3H4 glycocalyx had an isoelectric point of 5.0 +/- 0.4 and was precipitable with anti-schistosomal antibodies. More than 60% of the radiolabeled glycocalyx was released into the medium by transforming parasites in 3 h and was recovered as high molecular weight material. Parasites labeled with periodate and fluorescein-thiosemicarbazide and then transformed had a corona of fluorescence containing microvilli, much of which was shed onto the slide. Material on cercariae labeled by lodogen-catalyzed iodination was also of high molecular weight and was antigenic. In conclusion, the cercarial glycocalyx appears to be composed of acidic high molecular weight fibrils which are antigenic and incompletely cleared during transformation.

Paper 11: Degradation of Lubricating Fluids in a Vacuum

1968 ◽  
Vol 183 (9) ◽  
pp. 81-89
Author(s):  
L. Laurenson ◽  
L. Holland ◽  
M. A. Baker
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Liquid Chromatography ◽  
Working Conditions ◽  
Low Molecular Weight ◽  
Gas Liquid Chromatography ◽  
Rotary Pump ◽  
Average Value ◽  
Rapid Scan ◽  
Cracking Products

Examination of oil vapours emitted from an oil-sealed rotary pump using gas–liquid chromatography and mass spectrometry showed their molecular weight was significantly less than the average value of the parent oil. It was suspected that the predominantly low molecular weight of the vapour was due to the evolution of inherent light fractions in the oil and to cracking products resulting from friction processes in the pump. To separate these effects small amounts of lubricants were subjected to controlled frictional working conditions under vacuum. The emitted vapour was analysed by a rapid scan mass spectrometer and the residual fluid examined for changes in composition by gas–liquid chromatography.

Functional organogels from lipophilic L-glutamide derivative immobilized on cyclotriphosphazene core

2006 ◽  
Vol 21 (5) ◽  
pp. 1274-1278 ◽  
Author(s):  
Tomohiro Shirosaki ◽  
Saleh Chowdhury ◽  
Makoto Takafuji ◽  
Dzhamil Alekperov ◽  
Galina Popova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Transmission Electron Microscopy ◽  
Transmission Electron Microscopy Observation ◽  
Low Molecular Weight ◽  
Microscopy Observation ◽  
The Core ◽  
Self Assembling ◽  
Transmission Electron ◽  
Gelation Test

A novel cyclotriphosphazene-based low-molecular weight organogelator was prepared by immobilization of six dialkylated L-glutamide derivatives on a cyclotriphosphazene core, and its ability as a self-assembling organogelator was investigated. The organogelator exhibited enhanced gelation ability and chirality, and thixotropic property for self-restoring to a gel state; this was compared to the corresponding L-glutamide-derived organogelator without the core. The gelation test, transmission electron microscopy observation, and circular dichroism (CD) spectral study showed that the gelation and aggregation ability were enhanced by immobilization onto the cyclotriphosphazene core. Gels in chloroform and cyclohexane-ethanol (95:5) mixture showed an unusual thixotropic property.

Verification of the Flory Theory of Random Reorganization of Molecular Weight Distribution. Kinetics of Methylsiloxane Polymerization

1967 ◽  
Vol 40 (3) ◽  
pp. 769-776 ◽  
Author(s):  
Jack B. Carmichael ◽  
James Heffel
Keyword(s):  
Molecular Weight ◽  
Liquid Chromatography ◽  
Molecular Size ◽  
Gas Liquid Chromatography ◽  
Flory Theory ◽  
Distribution Kinetics ◽  
Linear Chains ◽  
Reaction Proceeds ◽  
Catalyzed Reactions ◽  
Kinetics Of

Abstract Distributions of linear and cyclic methylsiloxanes were determined by gas liquid chromatography during acid clay catalyzed reactions of equal molar amounts of D4[D= (CH3)2SiO] and MM[M= (CH3)3SiO1/2 at 80° C. Theoretical and experimental distributions of the linear siloxanes are compared as a function of time. The relatively large amounts of MD4M and MD8M present after 0.5 h indicate that D4 initially enters the linear chains as a unit. Sufficient reorganization has occurred after 0.5 h that the distribution of MD10M through MD13M is approximately random. The distribution of shorter chains becomes increasingly random as the reaction proceeds toward equilibrium. A corollary to the above conclusions is that the rate constant for propagation of dimethylsiloxanes appears to be approximately independent of molecular size.

Application of Gas-Liquid Chromatography to the Thermodynamics of Polymer Solutions

1972 ◽  
Vol 45 (6) ◽  
pp. 1638-1645
Author(s):  
D. Patterson ◽  
Y. B. Tewari ◽  
H. P. Schreiber ◽  
J. E. Guillet
Keyword(s):  
Molecular Weight ◽  
Liquid Chromatography ◽  
Polymer Solution ◽  
Gas Phase ◽  
Infinite Dilution ◽  
Solution Thermodynamics ◽  
Gas Liquid Chromatography ◽  
High Polymer ◽  
Activity Data ◽  
Polymer Systems

Abstract It has been well established that gas—liquid chromatography (glc) can give accurate thermodynamic data on binary solutions where the components differ considerably in volatility or molecular weight. The substance of lower molecular weight (component 1) is injected into the moving gas phase and dissolves at effectively infinite dilution in the stationary liquid phase. This is formed by the higher molecular weight material, for example, squalane, biphenyl, dinonyl phthalate, glycerol, or the higher n-alkanes such as C16, C24, C36, etc. The convenience of the technique is such that activity coefficient data have already been obtained for hundreds of systems. In contrast, activity data are available for far fewer high polymer systems, in part certainly because of the need to use the laborious vapor sorption technique. While that technique gives activity data as a function of concentration, it would still be desirable to have data at infinite dilution for a variety of systems in order to test contemporary theories of polymer solution thermodynamics. Recently Guillet and coworkers have applied the glc technique to systems in which the stationary phase is a high polymer. (J. E. Guillet and coworkers refer to the gas-phase component as the molecular “probe”. This avoids the glc teminology in which that component is the solute and the stationary-phase polymer would be the solvent. This terminology is confusing to polymer chemists used to solutions where the polymer is the solute, being present at low, rather than high, concentrations.) Their primary interest has been to demonstrate the versatility of the technique in determining first- and second-order phase transitions, degrees of crystallinity, and other physical characteristics of the polymer, while the present communication considers the determination of thermodynamic quantities. It has been prompted by comments from several workers who have noted the difficulty of applying the usual thermodynamic equations of glc which yield γ1∞, the activity coefficient of component 1 at infinite dilution [Equations (5) and (6)]. The equations require an exact value of the molecular weight of component 2, making difficult their use for polymer systems. Our main objective is to resolve this problem. However, we also wish to stress the utility of the technique in providing data with which to test contemporary theories of polymer solution thermodynamics. We therefore comment on equations which directly relate experimental glc data to the interaction parameter, χ, of polymer solution thermodynamics.

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