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  • Cell & Developmental Biology  (8)
  • Wiley-Blackwell  (8)
  • American Ceramics Society
  • 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
    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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  • 3
    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
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    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
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Identification and localization of integrin subunits in oocytes and eggs of the mouse (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 211-220 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Integrin ; Oocyte ; Egg ; Mouse ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Results of a recent study have implicated egg integrins in sperm binding to the egg plasma membrane (Blobel et al., 1991: Nature 356:248-252). In this report, immunoprecipitation was used to identify, and confocal immunofluorescence microscopy was used to localize, several different integrin subunits in mouse eggs. Antibodies to α2, α5, αv, and β1 subunits, as well as antibodies to the fibronectin receptor (FNR; α5β1 and/or α3β1) and vitronectin receptor (VNR; αvβ3 and/or αvβ5), detect polypeptides of the appropriate molecular weights following immunoprecipitation. β1 is localized preferentially to either the microvillar or amicrovillar membrane/cortical regions of eggs, and these asymmetric localizations depend on the antibody used. Proteins recognized by anti-FNR antibodies are localized preferentially to the amicrovillar membrane/cortical region. Germinal vesicle-intact oocytes display a symmetric plasma membrane distribution using β and FNR antibodies, and the asymmetric distribution develops as a consequence of oocyte maturation and is clearly observed by metaphase I. In contrast to the membrane localization of these integrin subunits, α2, α5, and VNR are predominantly localized in the cytoplasm of both oocytes and eggs. In the oocyte, each of these integrin subunits is uniformly distributed throughout the cytoplasm. Oocyte maturation is associated with a redistribution of α5 and VNR, leading to an asymmetric cytoplasmic distribution with an increased localization towards the spindle. αv, which is localized in the plasma membrane/cortex of both oocytes and eggs, does not show such a change during oocyte maturation. Results of these experiments are discussed in the context of a role for integrins in mediating sperm plasma membrane-egg plasma membrane interactions leading to egg activation. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080400210
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Activation of a Gi protein in digitonin/cholate-solubilized membrane preparations of mouse sperm by the Zona pellucida, an egg-specific extracellular matrix (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 355-363 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Sperm ; Signal transduction ; G protein ; Zona pellucida ; Receptor ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Mammalian sperm possess guanine nucleotide-binding regulatory proteins (G proteins) that are involved in signal transduction pathways leading to zona pellucida (ZP)-mediated acrosomal exocytosis. We have previously examined ZP-G protein dynamics in mouse sperm homogenates, as well as cell-free membrane preparations, and our data support the existence of ZP receptor-G protein complexes in sperm membranes. However, the composition of this complex has not been identified due to experimental limitations of the membrane preparations. In the present study, a detergent-solubilized preparation from mouse sperm membranes that retained the signaling properties of cell homogenates and cell-free membrane preparations was developed using buffers containing digitonin and cholate. GTPγS, a poorly hydrolyzable analogue of GTP, bound to these solubilized preparations in a specific and concentration-dependent fashion that reached saturation at 100 nM. Incubation of this solubilized membrane preparation with heat-solubilized ZP resulted in an increase in specific GTPγS binding in a concentration-dependent manner, with a maximal response at 4-6 ZP/μl. Mastoparan (50 μM) increased GTPγS binding to levels similar to that seen with solubilized ZP. Mastoparan plus ZP stimulated GTPγS binding to the same extent as mastoparan or ZP alone. Pertussis toxin completely inhibited ZP-stimulated GTPγS binding and decreased mastoparan-stimulated GTPγS binding by 50-60%. Purified ZP3, the ZP component that possesses quantitatively all of the sperm binding and acrosomal exocytosis-inducing activities of the intact ZP, stimulated GTPγS binding to an extent similar to that of solubilized ZP. The properties of this solubilized membrane preparation are similar to those found in the cell homogenates and cell-free membrane preparations, suggesting that the components involved in ZP3-mediated signal transduction are effectively solubilized and are responsive to the ZP3 ligand. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080400312
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Phosphate uptake and control of fibroblast growth (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 115-128 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Previous studies have shown that growth to quiescence of fibroblast-like cells is accompanied by a large decrease in the rate of phosphate uptake. Since 3T3 cells can be arrested in the G1 (or G0) phase of the cell cycle by lowering the concentration of phosphate in the medium, we examined the possibility that the decline in phosphate uptake observed during growth to quiescence might be a key event in the inhibition of DNA synthesis and cell division.The experimental approach consisted of controlling the rate of phosphate uptake by varying the phosphate concentration in the medium. Kinetic experiments showed that phosphate uptake in both growing and quiescent cells was partly accounted for by simple diffusion as well as carrier-mediated uptake. In fact, diffusion of phosphate into the growing cells was 2.5-fold greater than in the quiescent cells.When phosphate uptake was measured in 3T3 cells plated at different initial densities, we found an inverse relationship between phosphate uptake and cell density, showing that phosphate uptake was correlated with growth rate and did not decline simply as a consequence of time in culture.Measurements of phosphate demonstrated that the lowered rate of phosphate uptake by quiescent cells was not due merely to a reduction of phosphate in the medium. To check the possibility that release of a previously described transport inhibitor might account for the decline in phosphate uptake observed as cells grow to quiescence, we removed media from growing and non-growing cultures and tested its ability to support phosphate uptake. We found that the medium from growing cultures supported a higher rate of phosphate uptake than the medium from the quiescent cultures did, indicating that a transport inhibitor was being released. In addition, we found that the amount of inhibitor released was proportional to the concentration of phosphate in the medium.To directly determine if the decline in phosphate uptake was a key event in the decline in DNA synthesis as cells grew to quiescence, we switched growing cultures to a medium with low phosphate immediately after cell attachment. This lowered the rate of phosphate uptake to a level below that of quiescent cells grown in the usual concentration of phosphate. This was done for 3T3, Polyoma virus-transformed 3T3, human diploid foreskin, and secondary chick embryo cells. Measurements of DNA synthesis and cell number showed that this lowered rate of phosphate uptake had virtually no effect on cell growth, directly demonstrating that the decline in phosphate uptake observed during growth to confluency was not causing the decline in DNA synthesis. In addition, measurements of intracellular phosphate pool size showed that changes in phosphate uptake were not directly paralleled by changes in intracellular phosphate pool size, and that intracellular phosphate pool size was not regulating DNA synthesis or cell division during growth to quiescence.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1040920114
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Serum-stimulated phosphate uptake and initiation of fibroblast proliferation (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 193-210 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Previous studies have shown that initiation of proliferation of density-inhibited fibroblasts by fresh serum is accompanied by a rapid increase in phosphate uptake. This increase might be a key event in the initiation of DNA synthesis. The present studies examined this possibility.Mouse 3T3, secondary chick embryo, or human diploid foreskin cultures were grown to quiescence in medium containing varying levels of serum. When proliferation of the cultures was initiated by addition of fresh serum, the changes in phosphate uptake were inversely related to the final increases in cell number. Additional experiments showed that the change in phosphate uptake following serum addition was determined by the level of phosphate uptake prior to serum addition.Addition of dexamethasone to quiescent 3T3 cultures caused them to proliferate but did not increase phosphate uptake. Similarly, trypsin or insulin stimulated proliferation of quiescent secondary chick embryo cultures, but caused little or no change in phosphate uptake.Quiescent 3T3 cultures switched to medium containing fresh serum and reduced levels of phosphate showed a decrease in both phosphate uptake and intracellular phosphate pool size. Cell proliferation in these cultures, however, was stimulated to the same degree as cultures switched to medium containing fresh serum and the normal amount of phosphate. In addition, quiescent secondary chick embryo cultures switched to medium containing fresh serum and no phosphate showed a decrease in the intracellular phosphate pool size. Thymidine incorporation and final cell number in these cultures, however, was stimulated to the same or higher degree than in cultures switched to medium containing fresh serum and the normal amount of phosphate. These results demonstrate that the rapid increase in phosphate uptake following addition of fresh serum to quiescent fibroblasts is not a necessary event for the initiation of proliferation.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1040900206
    Standort Signatur Erwartet Verfügbarkeit
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