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  • 1
    ISSN: 1573-5028
    Keywords: cDNA ; light-harvesting complex ; peridinin-chlorophyll a-binding protein ; dinoflagellate ; Symbiodinium sp. ; transit peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract mRNA from the dinoflagellate Symbiodinium sp. isolated from the staghorn coral Acropora formosa was used for the construction of cDNA libraries. A cDNA clone was identified which encoded the precursor of peridinin-chlorophyll a-binding protein (PCP), including a 52 amino acid transit peptide and the 313 amino acid mature protein. The deduced amino acid sequence clearly contains an internal duplication, implying that amongst dinoflagellates the M r 35 000 form of PCP has arisen by duplication and fusion of genes encoding the M r 15 000 form. This is the first reported sequence of a dinoflagellate light-harvesting protein. The anatomy of the mature protein and the transit peptide are discussed.
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  • 2
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tension responses of rat ventricular trabeculae subjected to successive ‘treatment’ with EGTA and Triton X-100 are described in order to investigate the effects of chemical ‘skinning’ techniques. In some preparations the alkaloid saponin was also used before Triton. Ultrastructural evidence is cited that the ‘EGTA-treatment’ fails to render cells ‘hyperpermeable’, i.e. freely permeable to small ions, whereas both saponin and Triton do so. In this paper we show that contractile responses like those described previously for the ‘EGTA-treated’ tissue can be obtained. However, more detailed examination shows that such behaviour is quantitatively distinct from that of conventionally skinned fibres in a way that is incompatible with the notion of ‘hyperpermeability’. The Ca-sensitivity after treatment with either EGTA, saponin or Triton is identical in our hands. However, this is not explained by free access of Ca (and EGTA) to the intracellular space in the EGTA-treated preparation: contractures develop with very different time courses, being fastest after Triton and only marginally slower when first exposed to saponin but a factor of five times slower after ‘EGTA-treatment’ alone. This applies to contractures evoked direct from Ca2+ concentration ⋍ 10−9 m to the test Ca2+ concentration at constant total buffer concentration. ‘EGTA-treated’ fibres develop tension when ATP or creatine phosphate (CrP) are removed from the bath. However, responses to ADP and to CrP changes persist with millimolar levels of ATP present, quite unlike the Triton-skinned muscle. Exposure to each of a variety of solutions for 24h produce preparations showing similar behaviour: whatever the explanation for the EGTA-‘skinning’ phenomenon it is not dependent upon low bathing Ca2+ concentration. On the basis of the functional characteristics described here, and the structural results cited, we conclude that the cell membrane continues to function as a selective permeability barrier after ‘EGTA-treatment’: this treatment does not produce a model of a selectively ‘skinned’ cardiac cell.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 184-198 
    ISSN: 1040-452X
    Keywords: Sperm ; Eggs ; Glycosaminoglycans ; Glycoconjugates ; Glycoproteins ; Zona pellucida ; Capacitation ; Acrosome reaction ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A frequently used mechanism for sperm-egg recognition in many species involves complementary protein-carbohydrate interaction. The usual paradigm includes complex glycoconjugates in reproductive tract fluids or on the eggs which are recognized by carbohydrate-binding proteins on the sperm surface. Various glycocojugates are utilized in the steps of sperm capacitation, sperm binding to the egg extracellular matrix and vitelline membrane and induction of the acrosome reaction. Several types of complex glycoconjugates are involved in these processes, including proteoglycans, lactosaminoglycans, sulfated fucose-containing glycoconjugates, and glycoproteins. There appear to be some structural similarities between active glycoconjugates; they are large in molecular weight and complex, and they are often sulfated, fucosylated, and attached to a protein through serine or threonine residues. In some species, the protein core of the glycoconjugates also participates in the interaction by limiting the binding of carbohydrates to sperm only of the relevant species, likely by providing the proper steric arrangement for the interaction. In other cases the protein core seems to serve more as a crosslinker of the carbohydrate moieties. This review discusses the types of glycoconjugates implicated in fertilization and the complementary lectin-like proteins found on sperm.
    Additional Material: 3 Ill.
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  • 4
    ISSN: 1432-1017
    Keywords: Myelin basic protein ; Palmitoyllysophosphatidylcholine ; NMR ; EPR ; C D ; Ultracentrifugation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The stoichiometry of palmitoyllysophosphatidylcholine/myelin basic protein (PLPC/MBP) complexes, the location of the protein in the lysolipid micelles, and the conformational changes occurring in the basic protein and peptides derived from it upon interaction with lysolecithin micelles were investigated by circular dichroic spectropolarimetry, ultracentrifugation, electron paramagnetic resonance (EPR) and 31P, 13C, and 1H nuclear magnetic resonance spectroscopy (NMR), and electron microscopy. Ultracentrifugation measurements indicated that well-defined complexes were formed by the association of one protein molecule with approximately 141 lysolipid molecules. Small-angle X-ray scattering data indicated that the PLPC/MBP complexes form particles with a radius of gyration of 3.8 nm. EPR spectral parameters of the spin labels 5−, and 16-doxylstearate incorporated into lysolecithin/basic protein aggregates, and 13C- and 1H-NMR relaxation times of PLPC indicated that the addition of the protein did not affect the environment and location of the labels and the organization of the lysolipid micelles. The data suggested that MBP lies primarily near the surface of the micelles, with segments penetrating beyond the interfacial region into the hydrophobic interior, but without any part of the protein being protected against rapid exchange of its amide groups with the aqueous environment. The basic protein acquired about 20% α-helix when bound to lysolipid micelles. Circular dichroic spectra of sequential peptides derived by cleavage of the protein revealed the formation of α-helical regions in the association with lysolecithin. Specific residues in myelin basic protein that participated in binding to the micelles were identified from magnetic resonance data on changes in the chemical shifts and intensities of assigned resonances, and line broadening of peaks by fatty acid spin-labels incorporated into the micelles.
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  • 5
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Direct coupling of supercritical fluid extractions with gas chromatography (SFE-GC) allows the extraction, concentration, and gas chromatographic analysis of organic analytes from solid samples to be performed in less than 1 h. Coupling of the supercritical fluid extraction step with a capillary gas chromatographic column is achieved using a standard on-column injector and requires no modification of the gas chromatograph. Maximum sensitivity is achieved and analyte degradation or loss is minimized since the extracted species are quantitatively transferred into the fusedsilica capillary gas chromatographic column where they are cryogenically focused prior to normal gas chromatographic analysis using flame ionization (SFE-GC/FID) or mass spectral (SFE-GC/MS) detection. SFE-GC analysis yields good chromatographic peak shapes that compare favorably with those obtained using standard on-column injection techniques. Class-selective extractions can be achieved by performing multiple SFE-GC analyses with different extraction pressures. The ability of coupled SFE-GC to yield rapid extraction and analysis of organic analytes is demonstrated for a variety of samples including polycyclic aromatic hydrocarbons (PAHs) from treated wood, urban dust, and river sediment, phenolic species from wood smoke particulates, nicotine from tobacco, biological markers from coal, and flavor components from food products.
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  • 6
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method for interfacing capillary supercritical fluid chromatography with a commercial quadrupole mass spectrometer (SFC/MS) has been developed that yields good chromatographic peak shapes and good sensitivity. No modification of the mass spectrometer is required, and a single instrument can be used for both SFC/MS and GC/MS with conversion between modes requiring less than 20 min. SFC/MS separations and chemical ionization mass spectra of wax components, a triazine pesticide metabolite, abietic acid, and high molecular weight polycyclic aromatic hydrocarbons are reported.
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  • 7
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Deuterated alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), and N-, S-, O-, and Cl-containing aromatics were prepared using a single reagent containing D2O, DCl, and chromium. The method requires little specialized equipment or synthesis expertise, and results in the exchange of all aromatic protons for deuterium. The isotopic purities of the deuterated products were controlled by the amount of reagent added, and in most cases, isotopic purities of 95% were achieved. Under appropriate conditions of temperature and time, no significant chemical degradation of the aromatic compounds occurred. The method also works well with complex mixtures and large (30 g) quantities of aromatic compounds as demonstrated by the deuteration of a mixture of polychlorinated biphenyls (Aroclor 1254) and a coal-derived anthracene oil.
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  • 8
    ISSN: 1040-452X
    Keywords: Seminal vesicle ; Prostate ; Bulbourethral gland ; Seminal plasma ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Heparin binds to bovine sperm and stimulates capacitation in vitro. Seminal plasma alters the ability of epididymal sperm to bind heparin, and several heparin-binding proteins (HBPs) have been identified in bull seminal plasma. This study had three objectives: (1) to identify production sites of seminal plasma HBPs, (2) to determine which HBPs bound to cauda epididymal sperm, and (3) to determine whether presence of HBPs was testosterone dependent. Proteins from bull or rat seminal vesicles, prostates, and bulbourethral glands were separated by heparin affinity high-performance liquid chromatography. HBPs were found in all accessory glands of rats and bulls, but the major source of bovine seminal plasma HBPs appeared to be seminal vesicles. Between 25% and 50% of the protein from each gland bound to the heparin column, and NaCl concentrations required to elute proteins ranged from 0.15 to 1.4 M. One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that major HBPs were relatively small, with molecular weights between 13 and 31 kDa, but some HBPs also exhibited higher molecular weights, between 40 and 100 kDa. Radioiodinated HBPs from each bovine gland were incubated with epididymal sperm. Labeled HBPs binding to sperm exhibited molecular weights of 14, 16, 24, and 30 kDa as determined by SDS-PAGE and autoradiography. The HBP content of the accessory sex glands decreased significantly in castrated rats and was restored to levels of sham-operated controls by testosterone replacement. Heparin-binding proteins may play a role in fertilization by attaching to sperm surfaces, enabling heparin-like glycosaminoglycans in the female reproductive tract to induce capacitation.
    Additional Material: 10 Ill.
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  • 9
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction (SFE) ; Solid phase extraction (SPE) ; On-line analysis ; Gas Chromatography ; Explosives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for the quantitative extraction of nitrotoluenes (2,3-dinitrotoluene, 2,4-dinitrotoluene and trinitrotolugene) from water using a BakerbondTM phenyl sorbent. The average solid phase extraction recoveries for spiked standards ranged from 80 to 95 percent for reagent water and 52 to 95 percent from well and surface water in the low ppb and ppt levels. After the nitrotoluenes had been trapped on the solid sorbent they were quantitatively eluted using SFE. Adding toluene to the extraction cell increased the rate of extraction, but did not improve analyte recovery versus unmodified CO2. The extracts were analyzed off-line with GC-ECD using an internal standard. Extraction losses were due to analyte breakthrough, and not from poor SFE recoveries. This demonstrates that supercritical fluid extraction is a suitable elution technique for analytes trapped on solid phase extraction sorbents.Also, a method for the direct on-line coupling of SPE to GC, using SFE, has been developed and evaluated. Supercritical CO2 is ideal for directly coupling SPE to GC, since carbon dioxide is a gas under ambient conditions. One potential problem of on-line SPE-SFE-GC is the presence of residual water trapped on the active sites of the Bakerbond13 phenyl sorbent. This problem was dealt with by using a split interface previously described by Hawthorne. From the results of this study, the relative standard deviation of the on-line SPE-SFE-GC interface was determined to be between 4 and 10 percent. In addition, there was no significant difference in the precision of the method with or without the use of an internal standard. A calibration curve was also constructed (r2 = 0.995) from spiked controls, demonstrating that the method is quantitative.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 1059-910X
    Keywords: Myelin ; Oligodendrocyte ; Schwann cell ; Picornavirus ; Immunoglobulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Remyelination in the central nervous system, originally thought to occur rarely, if ever, is now an established phenomena in multiple sclerosis patients. However, the extent of myelin repair is incomplete and limited. Experimental models of central nervous system demyelination provide an opportunity to study the cellular and molecular events involved in remyelination. These models may provide some clue to why remyelination in multiple sclerosis is incomplete as well as suggest potential methods to stimulate central nervous system repair. In this review we examine the morphological aspects of central nervous system remyelination and discuss both spontaneous and induced remyelination in multiple sclerosis and experimental models of central nervous system demyelination. We give special emphasis to the Theiler's virus model of central nervous system demyelination and its usefulness to identify therapeutic agents to promote remyelination. The role of immunoglobulins in promoting remyelination in both the Theiler's model system and in multiple sclerosis is discussed. Finally, we examine the potential physiological role of demyelination and remyelination and its relationship with clinical manifestations of central nervous system disease. © 1995 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
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