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  • 1
    Digitale Medien
    Digitale Medien
    Increasing tubC β-tubulin synthesis by placing it under the control of a benA β-Tubulin upstream sequence causes a reduction in benA β-tubulin level but has no effect on microtubule function (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 214-220 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Aspergillus ; benomyl ; chimeric gene ; tubulin mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have constructed a chimeric β-tubulin gene that places the structural gene for the tubC β-tubulin of Axpergillus nidulans under the control of the benA β-tubulin promoter. Introduction of cither this chimeric gene or a second wild-type ben.A gene into a benomyl-resistant benA22 strain causes it to become benomyl sensitive, indicating that the introduced genes are functional. Analysis of the tubulin proteins synthesized in benA22 strains into which a second wild-type benA β-tubulin gene was transformed showed that the total amount of β-tubulin protein was the same as in the parental strain with a single benA gene. Thus the level of β-tubulin must be regulated. This was also true of transformants carrying an extra copy of the chimeric β-tubulin gene. The total amount of β-tubulin was the same as in the parental strain. Two-dimensional gel analysis showed that the endoge-nous benA22 and the introduced chimeric tubC gene contributed equally to the total β-tubulin pool. Th; fact that one-half of the benA β-tubulin could be replaced by tubC β-tubulin with no effect on the growth of the cells suggests that the benA and tubC β-tubulins are functionally interchangeable.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970160308
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Molecular routes to materials in New York (1992)
    Weinheim : Wiley-Blackwell
    Advanced Materials 4 (1992), S. 443-445 
    Details
    ISSN: 0935-9648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/adma.19920040617
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  • 3
    Digitale Medien
    Digitale Medien
    A guanine nucleotide-binding regulatory protein in human sperm mediates acrosomal exocytosis induced by the human zona pellucida (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 78-86 
    Details
    ISSN: 1040-452X
    Schlagwort(e): G protein ; Pertussis toxin ; ADP-ribosylation ; Human sperm ; Acrosome reaction ; Zona pellucida ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Guanine nucleotide-binding regulatory proteins play key intermediary roles in regulating zona pellucida-mediated acrosomal exocytosis in mouse and bull sperm. Since human sperm possess a Gi-like protein and undergo the acrosome reaction in response to the human zona pellucida, we investigated whether this G protein plays a regulatory role in this exocytotic process. Zonae pellucidae isolated from eggs that had been inseminated but had shown no signs of fertilization after retrieval for in vitro fertilization and embryo transfer were pooled into groups of ≥50 in order to reduce variability in biological responses due to the possible presence of ZP that had undergone modifications associated with the polyspermy block. Acid-solubilized zonae pellucidae were incubated with capacitated sperm, and the sperm then assessed for the acrosome reaction using both the P. sativum agglutinin and chlortetracycline fluorescence assays; both assays gave similar results. Sperm incubated with solubilized zonae pellucidae at a final concentration of 2, 4, or 6 ZP/μl underwent acrosomal exocytosis to a similar extent as compared with A-23187. Sperm were incubated with 1 μg/ml pertussis toxin during capacitation to functionally inactivate the Gi-like protein. Pertussis toxin treatment of sperm did not affect sperm motility and the ability of the cells to bind to structurally intact zonae pellucidae. Pertussis toxin, however, completely inhibited the percentage acrosome reactions induced by solubilized zonae pellucidae. By contrast, the A-23187-induced acrosome reaction was insensitive to PT treatment. Pertussis toxin inhibition of the zona pellucida-induced acrosome reaction occurred in a concentration-dependent manner with maximal effects observed at 100 ng/ml PT. These data suggest that the pertussis toxin-sensitive Gi-like protein in human sperm plays an important regulatory role in the acrosome reaction induced by the human zona pellucida.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080310114
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Activation of a G protein in mouse sperm by the zona pellucida, an egg-associated extracellular matrix (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 297-306 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Acrosome reaction ; Signal transduction ; Pertussis toxin ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Mammalian sperm possess a guanine nucleotide-binding regulatory protein (G protein), with properties similar to Gi, that appears to be involved in the signal transduction pathway required for zona pellucida (ZP)-mediated acrosomal exocytosis. Mouse sperm treated with pertussis toxin (PT), a toxin that functionally inactivates Gi proteins, bind to the ZP of mouse eggs but are inhibited from undergoing acrosomal exocytosis. We have measured high-affinity GTPase activity and GTPγ[35S] binding in mouse sperm homogenates incubated in the absence and presence of ZP glycoproteins isolated from either ovulated eggs or from ovarian homogenates to determine whether this extracellular matrix can activate the sperm-associated Gi protein. An increase in GTP hydrolysis (∼50% over basal activity) and GTPγ[35S] binding (∼25-60% over basal activity) is observed when sperm homogenates are incubated in the presence of solubilized ZP glycoproteins, and the increase in GTPase activity is dependent on the concentration of ZP added to the homogenates. Accompanying this increase is a reduction in the ability of PT to catalyze in vitro [32P]ADP-ribosylation of a Mr = 41,000 sperm Gi protein, suggesting that the increase in GTPase activity and GTPγ[35S] binding is associated with the activation of a PT-sensitive sperm G protein(s). The ability of the ZP to stimulate high-affinity GTPase activity in these homogenates appears to be dependent on the capacitation state of the sperm from which the homogenates are prepared. These data suggest that a component(s) of the ZP may function in a manner similar to that of other ligands by binding to a sperm surface-associated receptor and subsequently activating a G protein coupled to an intracellular signal transduction cascade(s) required for induction of acrosomal exocytosis.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080310411
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  • 5
    Digitale Medien
    Digitale Medien
    Rapid, nonradioactive, and quantitative method to analyze zona pellucida modifications in single mouse eggs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 91-93 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Zona pellucida ; Egg activation ; Mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: A rapid, nonradioactive method to monitor the ZP2 to ZP2f conversion in the zona pellucida of single mouse eggs has been developed. This assay is based on the chemiluminescent detection of biotinylated ZP2 and ZP2f following electrophoresis under reducing conditions and electrophoretic transfer to Immobilon P. This method is about 10 times faster and detects similar extents of ZP2 to ZP2f conversion following A23187-induced egg activation, when compared to the commonly used radioiodination procedures. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080380115
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  • 6
    Digitale Medien
    Digitale Medien
    Kinetic and thermodynamic considerations of the bracketing method: Entropy-driven proton-transfer reactions in a Fourier transform mass spectrometer (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1602-1607 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several reports of experimentally derived proton affinity values and gas-phase basicity values for amino acids and peptides have recently appeared in the literature. Here, we show that the thermodynamic quantity that is measured by the Fourier transform mass spectrometry proton transfer bracketing of amino acids and peptides is gas-phase basicity and not proton affinity. Both experimental and theoretical evidence supports this conclusion. The difference between the values determined by proton transfer bracketing measurements for lysine versus leucine is consistent with a difference in gas-phase basicity rather than proton affinity. The rate of proton transfer from protonated lysine to a series of reference compounds have been measured. Entropy-driven, endothermic proton transfer is found to occur at the collision rate. Recent ab initio and semi-empirical calculations of the proton affinity of lysine are found to agree with the value that is derived from bracketing studies when one assumes that gas-phase basicity is measured. While entropy-driven reactions have been observed previously in high-pressure mass spectrometers, this is the first evidence for such reactions at low pressure in a Fourier transform mass spectrometer.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210281236
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  • 7
    Digitale Medien
    Digitale Medien
    Differential detergent fractionation of isolated hepatocytes: Biochemical, immunochemical and two-dimensional gel electrophoresis characterization of cytoskeletal and noncytoskeletal compartments (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 265-277 
    Details
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Two-dimensional (2-D) gel electrophoresis is often used in toxicologic and metabolic studies to assess treatment- or stage-specific changes in protein synthesis, degradation or posttranslational modification. When combined with cell fractionation studies the detectability of low abundance proteins is enhanced, and changes in subcellular distribution of proteins can also be monitored. Detergent fractionation is a simpler alternative to differential pelleting, which partitions cellular constituents into functionally distinct populations while preserving cytoskeletal integrity. We defined and characterized a differential detergent fractionation (DDF) protocol to enable protein dynamics in cytoskeletal and noncytoskeletal compartments of isolated hepatocytes to be monitored simultaneously. Rat hepatocytes were maintained in suspension culture and fractionated by sequential extraction with detergentcontaining buffers (digitonin/EDTA, Triton/EDTA, Tween/deoxycholate). DDF reproducibly yielded four electrophoretically distinct fractions enriched in cytosolic, membrane-organelle, nuclear membrane and cytoskeletal-matrix markers, respectively. Immunoblotting with over 20 different antibodies corroborated the selectivity of fractionation and was used to characterize the distribution profiles of cytoskeletal (actin, tubulins, cytokeratins, vinculin, myosin, desmoplakins, fodrin, nuclear lamins) and noncytoskeletal proteins (heat-shock 70 proteins, glutathione-S-transferase, calpains, carbamoyl phosphate synthetase, etc.), as well as to identify spots in 2-D gels. Detergent buffers were compatible with equilibrium or nonequilibrium 2-D gel electrophoretic analysis. Extensive 2-D maps of acidic and basic proteins in each fraction were generated along with a tabular listing of Mr and pI. Thus, DDF reproducibly partitions hepatocytic proteins into functionally distinct cytoskeletal and noncytoskeletal compartments that are readily analyzed by 2-D gel electrophoresis. DDF is simple, applicable to use with other cell types or culture systems and is especially useful when biomaterial is limited (i.e., clinical studies).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elps.1150150146
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  • 8
    Digitale Medien
    Digitale Medien
    Comparisons of protein changes in human and rodent hepatocytes induced by the rat-specific carcinogen, methapyrilene (1993)
    Weinheim : Wiley-Blackwell
    Electrophoresis 14 (1993), S. 157-161 
    Details
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: There is a growing concern that the rodent biossay may not always serve as an appropriate model to assess the carcinogenic risk for humans exposed to certain compounds. Mechanistic research that examines the effects of a compound in rodent and man could help in the interpretation of bioassay results. This paper reports a novel use of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) technology to assess similarities and differences in the response of rodents and humans to the rat-specific hepatocarcinogen, methapyrilene (MP). A sequential examination of rodent and human hepatic proteins was conducted following in vivo exposure of rats and mice and in vitro exposure of rat, mouse, and human hepatocytes to MP. Results showed that covalent modifications observed in rats and mice in vivo were duplicated both qualitatively and quantitatively in the corresponding in vitro systems and that these modifications correlated with carcinogenic susceptibility. Covalent modifications in human hepatocytes were minimal despite exposure to concentrations of MP that were 6-fold higher than those used in rodent hepatocytes. These studies suggest that in the case of MP the rat is not the most appropriate model for assessing the human situation. Furthermore, these data show that in vitro-in vivo comparisons based on 2-D PAGE may provide adjunctive information for extrapolating rodent toxicity/bioassay results to human risk assessment.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elps.1150140124
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