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  • Cell & Developmental Biology  (1,145)
  • General Chemistry  (1,028)
  • Organic Chemistry  (891)
  • 1990-1994  (3,064)
  • 1970-1974
  • 1910-1914
  • 1990  (3,064)
Collection
Keywords
Publisher
Years
  • 1990-1994  (3,064)
  • 1970-1974
  • 1910-1914
Year
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and evaluation of two novel “mixed” chiral stationary phases deriving from tyrosine: Csps designed for the resolution of either π-acid or π-basic racemates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 106-119 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separations ; chiral stationary phases ; tyrosine chiral selector ; γ-mercaptopropyl silica gel ; HPLC, chiral recognition mechanisms ; mobile phase optimization ; UV-vis charge transfer band ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and chromatographic evaluation of two novel chiral stationary phases (CSPs) deriving from (S)-tyrosine are reported. The chiral graft has been designed in order to bear both π-acid and π-basic sites, each one being connected to a distinct asymmetric centre. An intramolecular π-π interaction may take place within these CSPs, leading to an energetically favoured conformation of the chiral selector (CS). The enantiorecognition ability of these CSPs was investigated for various classes of either π-acid or π-basic racemates. It is shown that these CSPs are able to separate simultaneously π-acid and π-basic racemates. Finally, chiral recognition mechanisms and mobile phase optimization are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020208
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical synthesis, absolute configuration, and stereochemistry of formation of 10-hydroxywarfarin: A major oxidative metabolite of (+)-(r)-warfarin from hepatic microsomal preparations (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 96-105 
    Details
    ISSN: 0899-0042
    Keywords: human liver ; P-450IIIA family ; 10-hydroxywarfarin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a diastereomerically pure 10-hydroxywarfarin [4-hydroxy-3-(2-hydroxy-3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one] was accomplished in three steps from racemic warfarin. The relative configuration of the synthetic product was established by conversion to a cyclic derivative followed by NMR and X-ray diffraction analysis. Absolute stereochemistry was determined by enzymatic conversion of either of the pure enantiomers of warfarin to a 10-hydroxy metabolite of known relative configuration. Metabolic formation of 10-hydroxywarfarin was studied using hepatic microsomal preparations from female rats and man. The formation of 10-hydroxywarfarin catalyzed by hepatic microsomes from both dexamethasone-treated rats and man was highly stereoselective [(R)/(S): 3.4-9.0] for (R)-warfarin. In contrast, little stereoselectivity was observed in reactions catalyzed by untreated rat liver microsomes. The resultant stereochemistry at the site of oxidation was also found to be highly dependent on substrate stereochemistry. (R)-Warfarin gave (9R;10S)-10-hydroxywarfarin with only a trace of the (9R;10R) isomer irrespective of which enzyme preparation was used for catalysis, while (S)-warfarin gave (9S;10R)-10-hydroxywarfarin with only a trace of the (9S;10S) isomer, again irrespective of which enzyme preparation was used for catalysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020207
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  • 3
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 128-128 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020211
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  • 4
    Electronic Resource
    Electronic Resource
    Racemates versus enantiomers in drug development: Dogmatism or pragmatism? (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 129-133 
    Details
    ISSN: 0899-0042
    Keywords: chiral drugs ; racemates ; eutomers ; distomers ; pharmacodynamic enantioselectivity ; pharmacokinetic enantioselectivity ; enantioselective interactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020302
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  • 5
    Electronic Resource
    Electronic Resource
    Stereoselective disposition of ibuprofen and flurbiprofen in rats (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 134-140 
    Details
    ISSN: 0899-0042
    Keywords: pharmacokinetics ; enantiomers ; 2-arylpropionates ; chiral inversion ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R)-2-Arylpropionates are often inverted to the pharmacologically active S-enantiomers in vivo, although there is significant interspecies variability in inversion. In order to provide a basis for determining the biochemical consequences of this unique process using rats as a model, it was important to establish the pharmacokinetic disposition of the enantiomers of ibuprofen, a drug well inverted in man and flurbiprofen, a drug apparently poorly inverted in man. Rats were dosed i.v. with a single dose of (R)-or (S)-ibuprofen (20 mg/kg), (R,S)-ibuprofen (40 mg/kg), (R)- or (S)-flurbiprofen (10 mg/kg), or (R,S)-flurbiprofen (20 mg/kg). Each treatment group consisted of six animals. Serial blood samples were withdrawn over a period of 6 h for ibuprofen and 10 h for flurbiprofen. These drugs were assayed in plasma by a stereospecific HPLC assay. The pharmacokinetics of the ibuprofen and flurbiprofen enantiomers were evaluated using a two-compartment open model with conversion of the R- to S-enantiomers in the central compartment. There was 50 ± 4% inversion of (R)-ibuprofen, a figure similar to that observed in man and (R)-ibuprofen had a higher clearance (12.6 ± 1.3 ml/min/kg) than (S)-ibuprofen (7.7 ± 0.7 ml/min/kg; P 〈 0.01). The clearance of (R)- flurbiprofen after racemate (2.3 ± 0.1 ml/min/kg) was higher than its clearance when administered alone (1.7 ± 0.2 ml/min/kg; P 〈 0.01), indicating a pharmacokinetic interaction between the enantiomers (most probably at plasma protein binding sites). A corresponding difference was not observed for ibuprofen. There was a small amount of inversion of (R)-flurbiprofen as determined by area analysis (4.5 ± 1.6%). However, this calculation may be in some error because of the interaction between the enantiomers. These data demonstrate quantitative similarities in the inversion of ibuprofen and flurbiprofen in rats and man, a useful basis for comparing the effects of these two drugs on fatty acid metabolism.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020303
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  • 6
    Electronic Resource
    Electronic Resource
    Stereochemical features of 1,4-benzodiazepin-2-ones bound to human serum albumin: Difference CD and UV studies (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 167-174 
    Details
    ISSN: 0899-0042
    Keywords: benzodiazepines ; circular dichroism ; difference spectroscopy ; human serum albumin ; stereospecific interaction ; chiral discrimination ; electronic absorption spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemistry of an achiral (Diazepam) and two chiral (3-methyl and 3-succinyloxy substituted) 1,4-benzodiazepin-2-ones interacting with human serum albumin (HSA) has been investigated by making use of difference absorption (UV) and circular dichroism (CD) spectroscopies. Evidence is obtained for a higher affinity with HSA for one of the two possible conformations of the seven-membered benzodiazepine ring. The red shift revealed by the absorption difference spectrum between the free and the bound drug accounts for the CD difference spectra observed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020308
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  • 7
    Electronic Resource
    Electronic Resource
    Interindividual variability in the enantiomeric disposition of ibuprofen following the oral administration of the racemic drug to healthy volunteers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 249-256 
    Details
    ISSN: 0899-0042
    Keywords: ibuprofen enantiomers ; R,S-ibuprofen ; enantiomer disposition ; pharmacokinetics ; human study ; interindividual variability ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The plasma disposition of the enantiomers of ibuprofen has been investigated following the oral administration of the racemic drug (400 mg) to 24 healthy male volunteers. The plasma elimination of (R)-ibuprofen was found to be more rapid than that of the S-enantiomer [plasma half-life: (R) 2.03 h; (S) 3.05 h; 2P 〈 0.001], resulting in a progressive enrichment in the plasma content of this isomer, some 64% of the total area under the plasma concentration time curves (AUC) being due to the pharmacologically active enantiomer. The influence of dose on the pharmacokinetic characteristics of the enantiomers of ibuprofen, over the range 200-800 mg, was investigated in three subjects. Examination of dosenormalized AUC values and oral clearance indicate the dose dependence of (R)-ibuprofen disposition.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020410
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  • 8
    Electronic Resource
    Electronic Resource
    Enantioselective binding of mephobarbital to plasma proteins (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 257-262 
    Details
    ISSN: 0899-0042
    Keywords: barbiturates ; stereoisomers ; protein binding ; albumin ; age dependence ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective protein binding of mephobarbital (MPB) was investigated in human plasma and human serum albumin solutions by equilibrium dialysis. A small but statistically significant difference was observed in the in vitro plasma protein binding of the enantiomers; (S)-MPB was ∼59% bound and (R)-MPB ∼67% bound. The binding to albumin [(S)-MPB: ∼29% bound, and (R)-MPB: ∼41% bound] was less than to plasma proteins but showed somewhat greater enantioselectivity, suggesting that albumin binding is a major source of the enantioselectivity in plasma. The effects of MPB concentration, of varying enantiomeric concentration ratio, and of phenobarbital on the enantioselective binding of MPB were studied. The effect of age was also investigated by measuring the binding in plasma from 8 young (18-25 yr) and 8 elderly (〉60 yr) male subjects who took single doses of MPB. The results were in close agreement with the in vitro binding data, and the binding of both enantiomers was marginally but significantly lower in the young compared with the elderly subjects. These differences in binding were consistent with previously observed pharmacokinetic differences between the two subject groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020411
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  • 9
    Electronic Resource
    Electronic Resource
    Immobilized serum albumin: Rapid HPLC probe of stereoselective protein-binding interactions (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 263-268 
    Details
    ISSN: 0899-0042
    Keywords: protein binding ; stereoselectivity ; immobilized human serum albumin ; HPLC chiral stationary phase ; chiral drugs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A human serum albumin-based HPLC chiral stationary phase (HSA-CSP) has been examined as a tool to investigate binding of chiral drugs to HSA and drug-drug protein-binding interactions. Rac-oxazepam hemisuccinate (OXH) was used as a model compound and the chromatographic retention (k′) of its enantiomers was determined after addition of displacers to the mobile phase. Compounds known to bind at the same site as OXH and at different sites were tested for their displacing capacities. Competitive binding interactions between the OXH enantiomers and displacers in the mobile phase were reflected by decreases in the k′s of (R)- and (S)-OXH. The results indicate that retention on the HSA-CSP accurately reflects binding to native HSA and the technique can determine enantioselective and competitive binding interactions at specific sites on HSA. The HSA-CSP was also able to recognize separate binding areas for (S)- and (R)-OXH.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020412
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  • 10
    Electronic Resource
    Electronic Resource
    An HPLC procedure for the enantiomeric purity of an optically active cytosine analogue using ligand exchange (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 275-279 
    Details
    ISSN: 0899-0042
    Keywords: nucleotide analogue ; antiviral ; chiral separation ; complexation ; ion-pairing ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An acylonucleotide analogue, 1-[3-hydroxy-2-(phosphonyl-methoxy)propyl]cytosine (HPMPC), has shown activity against herpes simplex Type I and Type II viruses. An HPLC separation of the R- and S-enantiomers of HPMPC by ligand exchange using a mobile phase containing phenylalanine as the chiral modifier and copper(II) as the metal ion is reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020414
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  • 11
    Electronic Resource
    Electronic Resource
    High-Performance liquid chromatographic resolution of oxamniquine enantiomers: Application to in vitro metabolism studies (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 269-274 
    Details
    ISSN: 0899-0042
    Keywords: α1-acid glycoprotein ; chiral-AGP ; in vitro studies ; chiral optimisation ; cytosolic enzymes ; oxamniquine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the HPLC analysis of oxamniquine enantiomers in liver fraction incubates, using a second-generation α1-acid glycoprotein-based column (Chiral-AGP). Oxamniquine is extracted from the incubation media by liquid-liquid extraction, using diethyl ether. The dried residue is redissolved in eluent, filtered, then injected directly onto the analytical column. The extraction method affords recoveries of oxamniquine of approximately 93%, at concentrations up to 525 μg/ml, with an average relative standard deviation of 5.9%. The limit of detection of the method (to give an SNR = 2 at 246 nm) is 0.3 ng on-column for the first eluting, laevorotatory enantiomer and 2.3 ng for the dextrorotatory isomer. The method allowed study of the depletion of oxamniquine enantiomers in liver postimicrosomal incubates. In the rat, a turnover of 21.9% was observed, with no apparent enantioselectivity. Similar observations were made for a mouse liver subcellular fraction incubation. The absence of enantioselectivity in this biotransformation may be attributable to the low substrate specificity of the oxidase or dehydrogenase enzymes involved.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020413
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  • 12
    Electronic Resource
    Electronic Resource
    Optical resolution and absolute configuration of a nonsteroidal antiinflammatory drug, 2-(10,11-Dihydro-10-oxodibenzo-[b,f]thiepin-2-yl)propionic acid (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 280-283 
    Details
    ISSN: 0899-0042
    Keywords: antiinflammatory drug ; 2-arylpropionic acid derivative ; CN-100 ; enantiomer ; resolution ; racemization ; absolute configuration ; chiral column ; direct separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound (±)-1 (CN-100) was efficiently resolved into a pair of enantiomers by fractional crystallization of the diastereomeric salts of (-)-and (+)-1-phenylethylamine. The purity of the enantiomers was determined using the chiral cellulose column (CHIRALCEL OJ®) which allowed direct separation of the enantiomers. A separation factor (α) of 1.73 was obtained. X-Ray crystallographic analysis of the (+)-isomer [salt of (-)-1-(4-bromophenyl)ethylamine] showed that this enantiomer has S-configuration. Biological studies have shown that only the (+)-isomer has antiinflammatory activity. Racemization of (-)-isomer was carried out by heating its propionic acid solution in the presence of mineral acid, such as HBr.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020415
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  • 13
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 288-288 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020416
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  • 14
    Electronic Resource
    Electronic Resource
    Stereoselective inhibition of thromboxane-induced coronary vasoconstriction by 1,4-dihydropyridine calcium channel antagonists (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 233-240 
    Details
    ISSN: 0899-0042
    Keywords: 1,4-dihydropypyridine enantiomers ; stereoselectivity ; thromboxane A2 (TxA2) ; coronary vasoconstriction ; calcium channel binding ; blood pressure ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biological activity of the (+)-S- and (-)-R-enantiomers of niguldipine, of the (-)-S- and (+)-R-enantiomers of felodipine and nitrendipine, and of rac-nisoldipine and rac-nimodipine was investigated in vitro and in vivo. Inhibition of coronary vasoconstriction due to the thromboxane A2 (TxA2)-mimetic U-46619 in guinea pig Langendorff hearts, displacement of (+)-[3H]isradipine from calcium channel binding sites of guinea pig skeletal muscle T-tubule membranes, and blood pressure reduction in spontaneously hypertensive rats were determined. The enantiomers were obtained by stereoselective synthesis. Cross-contamination was 〈0.5% for both S- and R-enantiomers of niguldipine and nitrendipine and 〈1% for those of felodipine. From the doses necessary for a 50% inhibition of coronary vasoconstriction, stereoselectivity ratios for (+)-(S)-/(-)-(R)-niguldipine, (-)-(S)-/(+)-(R)-felodipine, and (-)-(S)-/(+)-(R)-nitrendipine of 28, 13, and 7, respectively, were calculated. The potency ratio racnisoldipine/rac-nimodipine was 3.5. Ratios obtained from binding experiments and antihypertensive activity were (+)-(S)-/(-)-(R)-niguldipine = 45 and 35, (-)-(S)-/(+)-(R)-felodipine = 12 and 13, (-)-(S)-/(+)-(R)-nitrendipine = 8 and 8, and rac-nisoldipine/rac-nimodipine = 8 and 7, respectively. Highly significant correlations were found between the in vitro potency of the substances to prevent U-46619-induced coronary vasoconstriction and their affinity for calcium channel binding sites as well as their antihypertensive activity. The mechanism of TxA2-induced coronary vasoconstriction in guinea pig Langendorff hearts can be readily explained by a transmembrane influx of extracellular Ca2+ susceptible to stereoselective blockade by 1,4-dihydropyridine calcium channel antagonists.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020408
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  • 15
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150101
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  • 16
    Electronic Resource
    Electronic Resource
    Vinculin (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 1-6 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160102
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  • 17
    Electronic Resource
    Electronic Resource
    Formation of miniasters in the cytoplasm of hexyleneglycol-treated sea urchin eggs (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 23-33 
    Details
    ISSN: 0886-1544
    Keywords: centrosome ; cytaster ; MTOG ; pericentriolar material ; 51 kD protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Miniasters formed in mitotic sea urchin egg after treatment with 5% hexylene-glycol were investigated with the combined techniques of indirect immunofluo-rescence using anti-tubulin and anti-51 kD protein antibodies and electron microscopy.The formation of miniasters was dependent on the mitotic cycle. In the cytoplasm of eggs treated with hexyleneglycol at early prometaphase, a small number of microtubule fragments was observed, whereas in those treated at pro-metaphase, many miniasters and microtubule fragments were seen. When treated at metaphase, we found a great number of miniasters: 250-350 in one egg. In contrast, no miniasters were seen in eggs treated at anaphase, although many long microtubules that spread throughout the cytoplasm were observed. In the eggs treated at telophase, we scarcely noticed microtubule structures in the cytoplasm. In the center of miniasters, granules were found, showing the same size and electron density as those of the microtubule-organizing granules (MTOGs). Furthermore, the 51 kD protein, a component of the centrosome and mitotic spindle, was observed to be localized in the region of miniasters.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970150105
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  • 18
    Electronic Resource
    Electronic Resource
    Purification and characterization of an 85 kDa talin-binding fragment of vinculin (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 41-50 
    Details
    ISSN: 0886-1544
    Keywords: adhesion plaques ; cytoskeletal interactions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vinculin and talin are adhesion plaque proteins which have been shown to interact with each other in vitro. In order to begin to investigate where the talin-binding domain is in vinculin, vinculin was digested with Staphylococcus aureus V8 protease to generate two major fragments of 85 and 30 kDa, and these fragments were purified. Nitrocellulose overlays with 125I-talin and the 125I-85 kDa vinculin fragment and sucrose density gradient centrifugation demonstrated that the talin-binding domain was localized to the 85 kDa vinculin fragment. Quantification of 125I-talin binding in the overlays showed that four times more talin bound to the 85 kDa fragment as compared to intact vinculin. Competitive immunoprecipitation experiments demonstrated that unlabeled 85 kDa fragment, was about three fold more effective at competing for 125I-85 kDa binding to talin than was unlabeled vinculin. These results suggest that the 30 kDa fragment inhibits the vinculin-talin interaction even though the talin-binding domain is localized in the 85 kDa fragment.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970150107
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  • 19
    Electronic Resource
    Electronic Resource
    Epidermal growth factor induces the accumulation of calpactin II on the cell surface during membrane ruffling (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 34-40 
    Details
    ISSN: 0886-1544
    Keywords: rat liver cells ; immunoprecipitation ; immunocytochemistry ; membrane-bound proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Confluent and proliferatively quiescent T51B rat liver epithelial cells provide a cellular model for the study of epidermal growth factor (EGF) effects in non-neoplastic cells. Immunoreactive calpactin II, a well-known substrate for EGF-receptor kinase, was found predominantly in the cytosol, although a second im-munoreactive pool was found in a Triton X-100-extractable membrane fraction. Stimulation with EGF resulted in a rapid and transient (2-;5 min) formation of ruffles at the cell surface and at the cell-cell contacts. Both calpactin II and filamentous actin were found co-localized at the membrane ruffles. Immunopre-cipitations of membrane-bound calpactin II from 32P-labeled cells indicate a transient EGF-dependent phosphorylation of calpactin II correlating with membrane ruffling. These results suggest a temporal (2-5 min) function for calpactin II at the plasma membrane during the EGF-induced mitogenesis of T51B cells.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970150106
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  • 20
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150201
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  • 21
    Electronic Resource
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    Role of microtubules in the organisation of the Golgi apparatus (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 67-70 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Identification and immunolocalization of cytoplasmic dynein in dictyostelium (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 51-62 
    Details
    ISSN: 0886-1544
    Keywords: microtubule-associated proteins ; intracellular motility ; CTPase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A high molecular weight microtubule binding protein has been isolated from homogenates of Dictyostelium. Because of its sedimentation velocity (20s), ATP-sensitive binding to microtubules. UV-vanadate-ATP mediated fragmentation, prominent CTPase activity, and its ability to produce limited microtubule movement in vitro, we consider this protein to be a form of cytoplasmic dynein. A polyclonal antibody monospecific to this protein was produced, and dynein's intracellular distribution in ameboid cells was examined by immunofluorescence. The antibody labels a punctate cytoplasmic pattern, localizes to a spherical region adjacent to the nucleus, and also appears to label the nuclei. The punctate staining pattern is consistent with cytoplasmic dynein's proposed function in organelle transport. The spherical juxtanuclear object stained is coincident with this cell's microtubule organizing center, an obvious termination point for minus-end directed microtubule motors. By immunofluorescence, there does not appear to be a substantial amount of dynein in the intranuclear mitotic spindles of Dictyostelium, These data provide evidence for localization of cytoplasmic dynein in cells, and suggest that Dictyostelium will be a useful system in which to study the molecular biology of microtubule-associated motor enzymes.
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    Recent progress on structural interactions of the endoplasmic reticulum (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 71-75 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970150203
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    Effects of brain microtubule-associated proteins on microtubule dynamics and the nucleating activity of centrosomes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 88-98 
    Details
    ISSN: 0886-1544
    Keywords: tau ; MAP2 ; dynamic instability ; microtubule nucleation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this paper, we report on the effect of brain microtubule-associated proteins (MAPs) on the dynamic instability of microtubules as well as on the nucleation activity of purified centrosomes. Under our experimental conditions, tau and MAP2 have similar effects on microtubule nucleation and dynamic instability. Tau increases the apparent elongation rate of microtubules in proportion to its molar ratio to tubulin, and we present evidence indicating that this is due to a reduction of microtubule instability rather than to an increase of the on rate of tubulin subunits at the end of growing microtubules. Increasing the molar ratio of tau over tubulin leads also to an increase in the average number of microtubules nucleated percentrosome. This number remains constant with time. This suggests that the number of centrosome-nucleated microtubules at steady state can be determined by factors that are not necessarily irreversibly bound to centrosomes but, rather, affect the dynamic properties of microtubules.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160401
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    Recruitment: The ins and outs of spindle pole formation (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 225-228 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    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
    Keywords: Aspergillus ; benomyl ; chimeric gene ; tubulin mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 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.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160201
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    Kinetic analysis of chemotactic peptide-induced actin polymerization in neutrophils (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 80-87 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; chemotaxis ; polymerization ; motility ; nucleation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Definition of the kinetics of ligand-activated actin polymerization in the neutrophil is important for ultimately understanding the mechanisms utilized for regulation of actin polymerization in this non-muscle cell. To better define the kinetics of formyl peptide (fMLP) -induced actin polymerization in neutrophils we determined F-actin content at 5 second intervals after activation of human neutrophils with a range (10-11-10-9M) of fMLP concentrations. The state of actin polymerization was monitored by quantifying F-actin content with NBD phallacidin binding in both flow cytometric and extraction assays. Results demonstrate three successive kinetic periods of fMLP-induced actin polymerization in neutrophils, a lag period, a 5 second period when rate of polymerization is maximal, and a period of declining rate of actin polymerization as F-actin content approaches a maximum. The duration of the lag period, the maximum rate of polymerization, and the maximum extent of polymerization all depend upon the fMLP concentration. The lag period varies from 0 to 12 seconds and is followed in 5-10 seconds by a 5 second burst of actin polymerization when the rate is as great as 9% increase in F-actin content per second. After the 5 second burst of polymerization, the rate of polymerization rapidly declines. The study defines three distinct kinetic periods of fMLP-induced actin polymerization during which important rate-limiting biochemical events occur. The mechanistic and motile implications of kinetic periods are discussed.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: No Abstarct.
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    URL: http://dx.doi.org/10.1002/cm.970170401
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    Myosin II antibodies inhibit the resorption activity of isolated rat osteoclasts (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 250-263 
    Details
    ISSN: 0886-1544
    Keywords: myosin ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present microinjection data in support of an indirect approach by which cytoplasmic protein interactions important in the processes of bone resorption can be elucidated. Three polyclonal antibodies (M1, M3, M5) raised against myosin II from perfused rat liver differently affected the actin-activated Mg ATPase of myosin II. These antibodies microinjected into isolated rat osteoclasts affected osteoclast morphology and activity in bone resorption. M1, which completely inhibited myosin ATPase activity at a antibody:myosin ratio of 10:1, initially promoted the extension/retraction motility of lamellipodia but eventually reduced the spread area of osteoclasts along the substrate after 20 hr. M3, which inhibited ATPase activity by 70%, had similar effects; however, M5, which weakly inhibited ATPase activity, neither promoted extension/retraction nor reduced spread area of osteoclasts. Immunofluorescence showed that these antibodies removed myosin II from the majority of actin filaments in injected osteoclasts. Because antibodies that did not bind to a myosin II column had little effect on the extension/retraction of lamellipodia or the osteoclast spread area, these data suggest that myosin II participates in the stabilization of osteoclast lamellipodia along the substrate. M1 injection strongly inhibited injected osteoclasts from excavating resorption lacunae in bone slices, compared to control antibody. M3 and M5 were less effective but also inhibited bone resorption. These data show that myosin II is functionally important in bone resorption and that the osteoclast-differentiated activity of bone resorption is a more sensitive assay for myosin activity than lamellipodia motility or cell morphology.
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    Polypeptides from the myxomycete Physarum polycephalum interacting in vitro with microtubules (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 267-275 
    Details
    ISSN: 0886-1544
    Keywords: microtubule-associated proteins ; cell cycle ; phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubule-interacting proteins have been studied in the lower eukaryote Physarum polycephalum. We show for the first time 1) the presence in Physarum amoebal crude extracts of at least six polypeptides that bind specifically to amoebal microtubules, 2) the binding between these proteins and mammalian microtubules, 3) the heat stability of two of these polypeptides (125 and 235 kDa), 4) the functional properties of a fraction containing a heat-soluble 125 kDa polypeptide, and 5) the phosphorylation of the 125 kDa polypeptide during two distinct periods of the cell cycle in Physarum synchronous plasmodia, first at late S/early G2 phase and second at late G2/prophase.
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    Plants contain highly divergent actin isovariants (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 276-290 
    Details
    ISSN: 0886-1544
    Keywords: isoforms ; cytoskeleton ; angiosperms ; synthetic peptides ; IEF-SDS PAGE ; Western blot ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin protein isovariants have been identified in animals with distinct cytoplasmic or muscle specific patterns of expression. Analysis of vascular plant actin gene sequences suggests that an even greater diversity should exist within the plant actin protein families, but previous studies on plant proteins have not demonstrated the presence of multiple actin isovariants. Antibodies recognizing a conserved amino-terminal plant actin peptide, a family of plant actin peptides from a variable region, and two monoclonal antibodies to conserved epitopes within animal actins were used to identify isovariants of soybean actin resolved by two-dimensional isoelectric focusing (IEF) sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Approximately six to eight actin isovariants with pi values ranging from 5.1 to 5.8 have been identified from soybean hypocotyls. Stems, leaves, and roots with varying amounts of most isovariants present in all four organs. Acidic isovariants were present in much higher levels in leaves and stems. Antisera with λ-class actin specificity detected a subset of three isovariants in all organs examined. One monoclonal and one antipeptide antisera are shown to react well with a wide variety of plant actin isovariants. Similar patterns of actin isovariants were detected in the distant angiosperms, Arabidopsis petunia, and maize. It is likely that many of these diverse classes of isovariants have been preserved throughout vascular plant evolution and reflect the ancient diversity within plant actin gene families. The extreme difference among isovariants implies the presence of a complex actin-based cytoskeletal system in plants.
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    Modulation of keratin intermediate filament distribution in vivo by induced changes in cyclic AMP-dependent phosphorylation (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 291-300 
    Details
    ISSN: 0886-1544
    Keywords: PtK1 keratin filaments ; electrophoresis ; autoradiography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of PtK1 cells with 5 mM acrylamide for 4 hr induces reversible de-phosphorylation of keratin in concert with reversible aggregation of intermediate filaments (Eckert and Yeagle, Cell Motil. Cytoskeleton 11:24-30, 1988). We have examined this phenomenon by 1) in vitro phosphorylation of isolated PtK1 keratin filaments and 2) combined treatments of PtK1 cells with both acrylamide and agents which elevate intracellular cAMP levels. PtK1 keratins were incubated in gamma-32P-ATP in the presence or absence of cAMP-dependent kinase (A-kinase) and cAMP. Levels of phosphorylation were analyzed by electrophoresis and autoradiography. Phosphorylation of keratin polypeptides (56 kD, 53 kD, 45 kD, 40 kD) occurred without added kinase, suggesting the presence of an endogenous kinase which remains with intermediate filaments in residues of Triton X-100 extracted cells. Phosphorylation levels were increased by A-kinase but not by cAMP alone, indicating the presence of cAMP-dependent phosphorylation sites in addition to sites phosphorylated by the endogenous kinase. To study the possible role of cAMP-dependent phosphorylation in acrylamide-induced aggregation of keratin filaments, we treated cells with acrylamide in the presence of 8-bromo-cAMP (brcAMP), pertussis toxin (PT), isobutylmethylxanthine (IBMX), or forskolin, which increase intracellular cAMP levels. The distribution and phosphorylation levels of keratin filaments, as well as intracellular cAMP levels, were determined for each of these treatments. In addition to aggregation and dephosphorylation of keratin filaments reported previously, treatment of cells with acrylamide alone also results in reduced levels of intracellular cAMP. 8-bromo-cAMP, IBMX, and forskolin prevent acrylamide-induced aggregation of keratin filaments and result in both normal levels of keratin phosphorylation and normal intracellular cAMP levels. PT was apparently ineffective. These observations suggest that 1) PtK1 keratins are phosphorylated by cAMP-dependent kinase and an endogenous, cAMP-independent kinase and 2) alteration of levels of cAMP-dependent phosphorylation may be involved in aggregation of keratin filaments in response to acrylamide.
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    Computerized analysis of flagellar motility by digitization and fitting of film images with straight segments of equal length (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 309-316 
    Details
    ISSN: 0886-1544
    Keywords: digitization ; flagellum ; image analysis ; microcomputer ; simplex ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Methods are described for computerized analysis of digitized images obtained by scanning photomicrographs of swimming sperm flagella. After storing a series of image frames in computer memory, the entire series is analyzed automatically. For each sperm image, the sperm head is located to obtain a starting point for analysis of the flagellum. This location is obtained by minimizing image intensity along a model of the sperm head outline. The flagellum is modelled by a series of straight segments of equal length: 0.5 or 1 μm. The angles between these segments are adjusted to give minimum image intensity along the line of the model as well as minimizing smoothing functions. Extensions to analyze a series of images in each frame, and to measure the positions of beads attached to the flagellar microtubules, are also described.
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    Effects of trypsin and low Ca2+ on zonulae adhaerentes between chick retinal pigment epithelial cells in organ culture (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 46-58 
    Details
    ISSN: 0886-1544
    Keywords: circumferential microfilament bundles ; intercellular adhesion ; cytoskeleton ; junctional complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The junctional complexes in chick retinal pigment epithelial (RPE) cells in situ contain unusually large zonulae adhaerentes (ZAs) composed of subunits termed zonula adhaerens complexes (ZACs). To determine whether the properties of the ZAs differ between RPE cells which contain ZACs, and MDCK cells which lack ZACs, we investi-gated the effects of treatment with trypsin and/or low Ca2+ by transmission electron microscopy and staining for F-actin. Treatment of RPE cells for 1 h with trypsin alone has no apparent effect on the morphology of the ZA in either MDCK or RPE cells. In contrast to the ZAs in MDCK cells, which split after 3 min in low Ca2+, the ZAs in chick RPE cells stay intact even after 2 h, although the intermembrane discs, i.e., the extracellular components of the ZACs, are no longer visible. After 30 min of treatment with trypsin and low Ca2+, the ZAs split in both cell types. The CMBs start to contract, translocate toward the cell interior, and eventually disappear. This process continues even when the RPE cells are returned to normal medium. New ZAs, composed of ZACs, form between RPE cells 3 h after return to normal medium. These findings suggest that the ZACs in the ZAs of RPE cells are not directly responsible for the increase in resistance to low Ca2+. They also show that the ZA-junctions in RPE cells are not only structurally different from those previously examined, but also behave differently in response to experimental manipulation.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170201
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    Structure and function of profilin (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 71-74 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170202
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    Behavior of C-shaped microtubule endings in the cell (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 59-67 
    Details
    ISSN: 0886-1544
    Keywords: Polytoma papillatum ; Megaselia scalaris ; protofilament ; mitosis ; meiosis ; spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The association of incomplete microtubule assemblies with either another incom-plete structure or complete microtubules was studied in two organisms, the phytoflag-ellate Polytoma papillatum and the phorid fly Megaselia scalaris, using transmission electron microscopy. In the alga, hook-shaped appendages on cytoplasmic and spindle microtubules were detected. These resulted from the lateral association of a curved ribbon of protofilaments with the surface of a complete microtubular wall. In the fly, an S-shaped protofilament sheet was found embedded in the kinetochore plate of a prometaphase I spematocyte. Tracing of the S-shaped element towards the spindle pole revealed that it was formed by the lateral junction of two curved protofilament sheets. In all cases, the C-shaped protofilament sheets represented the endings of complete micro-tubules. Incomplete microtubules are generally considered as representing intermediates of microtubule assembly and disassembly. Since high molecular weight proteins are believed to be responsible for maintaining microtubule-microtubule spacing, it is hypo-thesized that the endings of growing and shrinking microtubules are sparsely studded with these proteins; their depletion allows lateral microtubule contacts. In addition, the microtubule-microtubule contacts may be rendered possible by the flexibility of the slender elongated microtubule-associated molecules. Relatively long C-shaped proto-filament appendages (0.6-1.4 μm) were detected in this study. Therefore, it is plausible to assume that the protofilament sheets are stabilized by contact with one another or with an intact tubule wall.
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    Identification and localization of proteins immunologically related to intermediate filament proteins in sea urchin eggs and embryos (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 75-86 
    Details
    ISSN: 0886-1544
    Keywords: intermediate filaments ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin spermatozoa, eggs, and embryos were labeled with the universal antibody against the intermediate filament proteins (anti-IFA) described by Pruss et al. [Cell 27:419-428, 1981] and with anti-beta-tubulin. Localization of these antibodies was by indirect immunofluorescence microscopy. Cytoskeleton of unfertilized eggs, prepared according to a procedure adapted from Kane [Exp. Cell Res. 162:495-506, 1986] or as described by Dufresne et al. [Biochem. Cell Biol. 66:780-791, 1988], and reacted with the anti-IFA demonstrate a uniformly stained background except for the nuclear areas, which appear as dark rings. During the first cell cycle, the anti-IFA staining pattern coincides with that of spindle-associated tubulin but not with the cortical pattern of microtubules. Swimming embryos reacted with the anti-IFA show a labeling located on the cilia and within the cytoplasm of each individual cell of the larva. In spermatozoa, the labeling occurs all along the flagellae. Immunoblots of proteins from eggs and embryos reveal one major protein of 117 kDa and sometimes a component of 66 kDa, both of which cosediment with tubulin during the isolation procedure of microtubules described by Vallee and Bloom [Proc. Natl. Acad. Sci. USA 80:6259-6263, 1983]. These data show that proteins homologous to the intermediate filament proteins reported in vertebrate cells are present in both gametes of sea urchins. The specific localization ofthese proteins in the spindle, the flagella, and the cilia suggest that they may play a significant role in the organization and function of the microtubular lattice of the spermatozoa and of the embryo.
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    Ca/Ba/Sr-induced conformational changes of ciliary axonemes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 187-196 
    Details
    ISSN: 0886-1544
    Keywords: axonemal shape changes ; Ca/Ba/Sr ; macrocilia ; Beroë ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Macrocilia of the ctenophore Beroë undergo Ca/Ba/Sr-dependent activation of ciliary beating and microtubule sliding disintegration [Tamm, J. Comp. Physiol. A163:23-31. 1988a: Tamm, Cell Motil. Cytoskeleton 11:126-138, 1988b; Tamm, Cell Motil. Cytoskeleton 12:104-112, 1989: Tamm and Tamm, Proc. Natl. Acad. Sci. U.S.A. 86:6987-6991, 1989]. Here we report that detergent-extracted macrocilia show an ATP-independent conformational change in response to high concentrations of Ca. Ba. or Sr ions. When applied locally by iontophoresis, these ions induce a rapid planar curvature of the distal end of the macrociliary shaft, followed by a slower relaxation to the rest position. Tip curling occurs in a direction opposite to the physiological Ca/Ba/Sr response. When applied uniformly in the bath, a threshold concentration of 10-1 M Sr is required to induce curling of the tip, and the distal ends remain curved. Calmodulin antagonists do not inhibit the tip curling response.Previous workers found that Ca induces changes in the helical shape of isolated doublet microtubules [Miki-Noumura and Kamiya, Exp. Cell Res. 97:451-453, 1976: Miki-Noumura and Kamiya. J. Cell Biol. 81:355-360, 1979; Takasaki and Miki-Noumura. J. Mol. Biol. 158:317-324, 1982] and sperm axonemes [Okuno and Brokaw, Cell Motil. 1:349-362. 1981] and suggested that conformational changes in microtubules may play a role in Ca regulation of ciliary motility. We propose that the Ca/Ba/Sr-induced curling of the macrociliary tip is due to similar helical changes of doublet microtubules, some of which in macrocilia are prevented from sliding by permanent connections (compartmenting lamellae) between adjacent axonemes within the shaft. Although the tip curling response does not appear to be directly relevant to the physiological Ca response of macrocilia, it provides a novel system for investigating Ca-induced conformational changes of microtubules independent of dynein-powered active sliding.
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    The iris diaphragm model of centriole and basal body formation (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 197-213 
    Details
    ISSN: 0886-1544
    Keywords: cell organelles ; MTOC ; development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper suggests that the formation and structure of the microtubular skeleton of centrioles and basal bodies can be derived from the following simple geometric principle. A closed ring of nine microtubular initiation sites defines (1) a template for the packing of 18 additional microtubular initiation sites, and (2) the shape of nine rigid arms. Upon swivelling of each arm around a point located four initiation sites away on the initial ring, the array unfolds in a manner similar to the opening of an iris diaphragm.As a consequence, the curved shape of the microtubular triplet blades arises together with the clockwise rotational sense of the slanted blades of the centriole or basal body. The final diameter of the centriole (basal body) self-adjusts. Furthermore, the pitch of the triplet blades, the taper of centrioles and basal bodies, and the change of slant of the blades towards the distal end can be derived. In addition, the model points to a method of replication of pro-centrioles (pro-basal bodies). The hypothesis was tested by the fitting of electron microscopical cross sections of centrioles of 3T3 cells to the geometric shapes predicted by the model.
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    Direct observation of microtubule dynamics in Reticulomyxa: Unusually rapid length changes and microtubule sliding (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 214-226 
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    ISSN: 0886-1544
    Keywords: actin ; cytoskeleton ; dynamic instability ; protozoa ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubule dynamics has been studied extensively in vitro, but comparatively little information is available on the in vivo behavior of microtubules. Here we report on the assembly, disassembly, and sliding of microtubules in the giant freshwater amoeba, Reticulomyxa. We have found that treating the cell with 0.25% trypsin induces the rapid formation of exceedingly flat areas within the reticulopodial network, allowing for the direct observation of microtubule behavior by DIC optics and computer-enhanced video microscopy. In flattened areas, microtubule sliding occurs at rates of between 1 and 6.5 μm/sec. The average rate of microtubule assembly is 1.6 μm/sec, while microtubule disassembly takes place at about 4 μm/sec and can reach up to 19.5 μm/sec. We also observed many cases where a microtubule forms a hairpin loop and eventually breaks, resulting in bidirectional disassembly from the point of breakage. Our observations demonstrate sliding of cytoplasmic microtubules in vivo. The high rates of microtubule assembly/disassembly in this cell type are difficult to reconcile with conventional views of association and dissociation processes at microtubule ends and suggest unconventional mechanisms for the growth and shrinkage of microtubules.
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    p34cdc2 Kinase is localized to distinct domains within the mitotic apparatus (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 227-235 
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    ISSN: 0886-1544
    Keywords: mitosis ; kinetochores ; cell division cycle ; protein phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Antibodies to both the C-terminal and the N-terminal regions of the 34 kd serinethreonine specific protein kinase, p34cdc2, were used to study the distribution of this protein in dividing cells and isolated chromosomes of the Indian muntjac. p34cdc2 was found to be present throughout the cytoplasm of dividing cells. In addition, a portion of cellular p34cdc2 was localized to the centrosome, kinetochore, and intercellular bridge and along kinetochore-to-pole microtubules during cell division. Tubulin-denuded metaphase kinetochores retained their association with p34cdc2. The detection of p34cdc2 within a variety of domains of the mitotic apparatus, in addition to the previous reported association with the centrosome [Bailly et al., EMBO J. 8:3985-3995, 1989; Raibowol et al., Cell 57:393-401, 1989] suggests that p34cdc2 may play a role in events associated with anaphases A and B as well as with the transition between interphase and mitosis.
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    Tubulin flux in the mitotic spindle: Where does it come from, where is it going? (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 93-98 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Antiparallel microtubule interactions: Spindle formation and anaphase B (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 99-103 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Toward a structural and molecular definition of the kinetochore (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 104-109 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Cytoskeletal dynamics in rabbit synovial fibroblasts: I. Effects of acrylamide on intermediate filaments and microfilaments (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 110-120 
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    ISSN: 0886-1544
    Keywords: vimentin ; collagenase ; cell shape ; gene expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rabbit synovial fibroblasts respond to changes in cell shape and cytoskeletal architecture by altering specific gene expression. We have tested the ability of acrylamide, a neurotoxin that alters the distribution of intermediate filaments in cultured PtKl cells, to induce metalloprotease expression in synovial fibroblasts. Cells treated with 2-20 mM acrylamide for 5 to 24 h underwent shape changes similar to cells treated with the tumor promoter phorbol myristate acetate. Intermediate filaments visualized with anti-vimentin antibodies did not collapse into a perinuclear cap in these rounded cells, but were still present in the extended cell processes. Unexpectedly, when actin was visualized in acrylamide-treated cells, extensive dissociation and clumping of microfilaments was observed. Concentrations of acrylamide 〉 10 mM were cytotoxic, but cells recovered completely after 24 h incubation with 5 mM acrylamide. Like other agents that alter cell shape and actin distribution in synovial fibroblasts, acrylamide also induced expression of the secreted metalloprotease collagenase. Although some recent evidence suggests that acrylamide may be able to exert its collagenase-inducing effects extra-cellularly, perhaps through transmembrane matrix receptors, our observation that this neurotoxin dramatically alters protein synthesis in synovial fibroblasts suggests that direct effects on cell metabolism may also play a role in acute acryl-amide intoxication.
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    Adaptation of Chlamydomonas phototaxis: I. A light-scattering apparatus for measuring the phototactic rate of microorganisms with high time resolution (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 230-244 
    Details
    ISSN: 0886-1544
    Keywords: photomovement ; population method ; stop response ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Phototaxis of the unicellular alga Chlamydomonas was studied with subsecond time resolution by using a newly developed taxigraph. The taxigraph determines the cell density in a particular volume element of a cuvette by measuring the amount of scattered light originating from the cells in this region. When the cell density is kept below 106/ml, a linear relationship exists between the scattered photon irradiance and the number of scattering particles. Time-dependent scattering changes can be used to determine direction and extent of phototactic activity as well as the time course of various adaptation processes. This communication describes design and performance of the taxigraph in detail and compares results obtained from Chlamydomonas cell populations with those obtained from single-cell analysis by using a computer-aided motion analysis system.The high time resolution of the taxigraph permits the study of rapid adaptational processes. Chlamydomonas strain 806 cells, which have been reported to show exclusively negative phototaxis, were found to turn transiently towards the light upon a rapid change in irradiance, before eventually moving away from it. The duration of the initial positive phototactic response was critically dependent on the magnitude of the irradiance increment. Adaptation to a step-up stimulus was consistently faster than to a step-down stimulation. The statistical nature of the switch from positive to negative phototaxis is demonstrated by single-cell observation.Different adaptation levels were characterised by stimulus-response curves, either in the presence of a constant background or following a defined delay after long previous irradiation. To describe the observed behaviour the existence of two adaptation processes, occurring on a vastly different time scale, must be anticipated: a rapid (seconds) background adaptation and a slow desensitisation in steady light which is completed in 30-40 min.
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    The yeast microtubule cytoskeleton: Genetic approaches to structure and function (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 1-6 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990) 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Macrophages form circular zones of very close apposition to lgG-Coated surfaces (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 260-270 
    Details
    ISSN: 0886-1544
    Keywords: Fc-receptors ; antibodies ; “frustrated” phagocytosis ; leucocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When phagocytes spread on surfaces coated with ligands such as IgG, they form a tight seal with the substrate. This seal excludes soluble macromolecules in the medium from the interface between the cell and substrate. In contrast, when cells spread on control surfaces that are not coated with ligands, the underside of the cell remains freely accessible to soluble proteins (Wright and Silverstein: Nature 309:359, 1984). We employed reflection-interference microscopy (RIM) to determine where the seal forms during interaction with ligand (IgG) -coated surfaces. Human monocyte-derived macrophages (MO) were plated at 37°C on dinitrophenylated (DNP)-glass coverslips (control substrate), IgM anti-DNP-DNP-coated glass (control substrate), or on IgG anti-DNP-DNP-coated glass (phagocytosis-promoting substrate). Live or fixed cells were examined by RIM. Spreading on control surfaces at 37°C was complete in 25 minutes, whereas spreading on IgG-coated surfaces was maximal within 15 minutes and resulted in cell-substrate contact area 1.6 × that of control cells. Within 1 h at 37°C, 90% of MO that spread on IgG-coated substrates, but not on control substrates, excluded macromolecules from their underside. A minor population of cells (19%) exhibited a uniform iron gray RIM appearance indicating an even, close approach to the substrate. These cells may represent early stages of frustrated phagocytosis. In contrast to cells on control substrates, 70% of cells on IgG-coated substrates developed continuous peripheral dark rings in RIM indicative of close association with the substrate. Essentially all cells with peripheral dark rings in RIM excluded macromolecules from their underside. Enclosed within this ring was an area of greater separation between the cell membrane and the substrate, as indicated by the lighter grey of this region in RIM and by the accessibility of substrate to anti-substrate antibody when breaks in the dark ring occur. Thus, MO can create a closed compartment between plasma membrane and substrate that excludes proteins in the surrounding medium, thereby protecting substances secreted into this space from potentially inhibitory substances in the medium.
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    Announcement (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 155-155 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970160209
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    Formation, transport, contraction, and disassembly of stress fibers in fibroblasts (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 14-21 
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    ISSN: 0886-1544
    Keywords: mitogenesis ; cytoskeletal dynamics ; actin ; myosin II ; fluorescent analog cytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Swiss mouse 3T3 fibroblasts grown on a solid substrate in the presence of 10% serum exhibit cell movement, organelle transport, and cytokinesis. When the serum concentration in the culture medium is decreased to 0.2% for 48 h the serum-deprived cells virtually stop locomoting, spread, decreased organelle transport, and exhibit extensive arrays of stress fibers that are visible with video-enhanced differential interference contrast microscopy and that also incorporate fluorescent analogs of actin and conventional myosin (myosin II). The stress fibers form in a constitutive mannet at the cytoplasm-membrane interface, transport toward the nucleus, and then disappear. The rate of transport of these fibers is quite heterogeneous with average rates in the range of 10-20 μm/h. When serum-deprived cells are stimulated with mitogens such as 10% serum or 10 nM thrombin, many of the stress fibers immediately begin to shorten, suggesting a contraction. The rate of shortening is approximately two orders of magnitude slower than that of unloaded smooth muscle cells. The fiber shortening is often accompanied by retraction of the edges of the cell and continues for at least the 1st hour post-stimulation.
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    Motion of individual human spermatozoa, both normal and lacking the outer dynein arms, during a continuous temperature rise (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 22-32 
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    ISSN: 0886-1544
    Keywords: image analysis ; sperm cell ; tracking ; motility ; velocity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of increasing temperature from 22-25°C to 37°C on various motion characteristics of individual normal human spermatozoa and spermatozoa lacking the outer dynein arms (LODA) was studied by using a new automatic microscopic tracking method. It was found that: (1) The curvilinear velocity (Vc, measured between 1-3 sec) of both normal and LODA spermatozoia, fluctuated more or less intensely between spermatozoa; this fluctuation was not thermodependent. (2) The average Vc in the two groups of spermatozoa increased with the rise in temperature at a similar rate (1μm/sec/°C), but LODA spermatozoa had an initial Vc lower than that of normal spermatozoa (12.5 ± 5.3 μm/sec and 34.2 ± 8.2 μm/sec, respectively). (3) The profile of the Vc increase associated with the temperature rise was different for the two groups of spermatozoa: for LODA spermatozoa it was linear between 25-37°C, whereas for normal spermatozoa a plateau was reached at about 31°C. (4) Various patterns of trajectory were found for both normal and LODA spermatozoa; these patterns were unrelated to temperature. However, LODA spermatozoa had more linear trajectories than normal spermatozoa. (5) Plots derived from reaction rate theory showed that the activation enthalpy, δH
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    Molecular cloning and expression of sea urchin embryonic ciliary dynein β heavy chain (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 33-46 
    Details
    ISSN: 0886-1544
    Keywords: dynein structure ; cilia ; development ; microtubule-based motility ; antibodies to dynein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The determination of the structure and the expression of dynein during embryonic development are central to the understanding of dynein function. As an important first step toward these objectives, cDNAs encoding portions of sea urchin ciliary dynein were identified by antibody screening of a sea urchin cDNA expression library. Bacause of the complete lack of protein sequence data, it was first necessary to prove the identity of the dynein cDNAs. Of the five cDNA inserts initially cloned, one, designated P72A1, was characterized extensively. Four independent criteria demonstrated that P72A1 encoded a portion of a dynein heavy chain. (1) The β-galactosidase-P72A1 fusion protein affinity-purified dynein-specific antibodies from crude antiserum. (2) Two other antisera to dynein, raised independently of the antiserum used to screen the cDNA library, reacted with the fusion protein. (3) A new antiserum raised against the fusion protein reacted with authentic dynein heavy chain on Western blots and stained embryonic cilia by indirect immunofluorescence microscopy. (4) Two new antisera, elicited against opposite ends of the P72A1 open reading frame, each reacted with authentic dynein heavy chain protein. Western blot analyses of dissociated dynein heavy chains revealed that P72A1 encoded a portion of the β heavy chain. Epitope mapping experiments confirmed the identity of P72A1 as part of the βheavy chain and also demonstrated that P72A1 encoded epitopes of the carboxyl-terminal fragment B domain of the dynein β heavy chain. Northern blot analyses of poly(A)+ RNA revealed that P72A1 hybridized with a large RNA species ca. 12.5 kb in length. The dynein mRNA concentration increased during embryonic development. Dot blot analyses of RNA isolated at various times after embryo deciliation demonstrated that the dynein β heavy chain mRNA accumulated rapidly in response to deciliation. The accumulation was similar to but not identical with the induction of tubulin mRNA in response to the same stimulus.
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    1,2-dioctanoylglycerol accelerates or retards mitotlc progression in Tradescantia stamen hair cells as a function of the time of its addition (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 190-203 
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    ISSN: 0886-1544
    Keywords: mitosis ; calcium ; diacylglycerol ; protein kinase C ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have treated living, intact stamen hair cells from the spiderwort plant, Tra-descantia virginiana, with 0.5 μg/ml or 60 μg/ml 1,2-dioctanoylglycerol, a potent and permeant activator of protein kinase C, and have observed the rates of progression of mitosis from prophase through anaphase. We have found that in addition to the concentration used, the time of initial treatment with 1,2-di-octanoylglycerol defines the response by the cells. The cells rapidly undergo nuclear envelope breakdown when this diglyceride is added in very late prophase, 0 to ∼8 min prior to the time of normal nuclear envelope breakdown. Anaphase onset occurs 28 min after nuclear envelope breakdown, rather than after the 33 min interval observed in untreated cells. Rapid progression through metaphase is also observed if cells are treated with 0.5 μg/ml 1,2-dioctanoylglycerol during prometaphase, up to 15 min after nuclear envelope breakdown. The addition of 0.5 μg/ml 1,2-dioctan oylglycerol in late metaphase, ∼26 min after nuclear envelope breakdown, results in sister chromatid separation slightly ahead of its normal time, 33 min after nuclear envelope breakdown, and in precocious cell plate vesicle aggregation, 3-5 min earlier than that observed in untreated cells. Treatment of cells with 60 μg/ml of 1,2-dioctanoylglycerol at any point during the interval from 0 to ∼5 min prior to nuclear envelope breakdown results in precocious entry into anaphase. If cells are treated with either 0.5 μg/ml or 60 μg/ml 1,2-dioctanoylglycerol earlier than 20 min before nuclear envelope breakdown, they do not enter mitosis, but instead revert to interphase without dividing. When 1,2-dioctanoylglycerol is added atother times during mitosis, the rate of subsequent mitotic progression is dramatically slowed; the cells require 〉55 min to progress from nuclear envelope breakdown to anaphase onset, though once in anaphase, the cells progress onward to cytokinesis at normal rates. Treatments of cells with 1,3-dioctanoylglycerol at any point during prophase, prometaphase, or metaphase are without effect on the rate of subsequent mitotic progression. The shifts in response by cells treated at specific times with 1,2-dioctanoylglycerol during mid- and late metaphase may be indicative of the existence of one or more regulatory switch points (i.e., checkpoints) just prior to anaphase onset.
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    Reorganization of cortical actin microfilaments and microtubules at preprophase and mitosis in wheat root-tip cells: A double label immunofluorescence study (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 76-87 
    Details
    ISSN: 0886-1544
    Keywords: antiactin ; cytochalasin B ; plant cytoskeleton ; tubulin ; oryzalin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following our recent description [McCurdy et al.: Protoplasma. 147:204-206, 1988] of arrays of transverse cortical microfilaments (MFs) in preprophase roottip cells of wheat (Triticum aestivum L. cv. Kite), we have performed double label immunofluorescence microscopy to correlate the formation of these arrays with the known rearrangement of cortical microtubules (MTs) that occurs during preprophase. At early preprophase, indicated by a broad (i.e., young) preprophase band (PPB) of MTs, actin MFs are transverse only in the central region of the cell cortex. By late preprophase, however, cells that possess a mature (i.e., narrow) PPB of MTs have arrays of transverse MFs that occupy the entire cortical surface of the cell. Thus, apart from the PPB zone, the transverse MFs in these arrays do not colocalize with transverse cortical MTs. Depolymerization of MTs using the herbicide oryzalin does not effect the arrays of cortical MFs; however, experiments using cytochalasin B in combination with oryzalin indicate that cellular MTs are necessary for the formation of the arrays of transverse cortical MFs. The arrays of cortical MFs disintegrate during prophase into short fragments of random, filamentous actin. This situation persists until the completion of cytokinesis. The absence of MFs during mitosis in densely-cytoplasmic meristematic cells of wheat root tips indicates that filamentous actin may not have a universal function in plant cell division. The possible function of the arrays of cortical MFs in preprophase cells is discussed.
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    Heterogeneity of microtubules in dividing sea urchin eggs revealed by immunofluorescence microscopy: Spindle microtubules are composed of tubulin isotypes different from those of astral microtubules (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 239-250 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; mitotic apparatus ; monoclonal antibodies ; sand dollar egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The heterogeneity of mitotic microtubules in dividing sea urchin eggs was investigated by indirect immunofluorescence using five anti-α-tubulin (YL1/2, DM1A, E3B8, D2D6, and 6-11B-1) and two anti-β-tubulin (E6B6 and DM1B) antibodies. These antibodies were divided into four classes in regard to the different immunofluorescent staining patterns: class I, which strongly stained both the spindle and aster (YL1/2, DM1A, E3B8 and E6B6); class II, which strongly stained the spindle but weakly stained the aster (D2D6); class III, which stained only the aster (DM1B); and class IV, which did not stain the mitotic apparatus (6-11B-1). These results suggest that tubulin isotypes are distributed differently in the sea urchin mitotic microtubules and that α-tubulin isotype(s) recognized by D2D6 is (are) localized mainly in spindle microtubules, whereas β-tubulin isotype(s) recognized by DM1B is (are) found only in astral microtubules.
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    Depolarization-controlled parameters of the ciliary cycle and axonemal function (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 251-265 
    Details
    ISSN: 0886-1544
    Keywords: Ciliary motility ; inclination ; polarity of beating ; active sliding velocity ; sliding translocation rate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Depolarization-induced cycles of a frontal cirrus of Stylonychia were investigated by applying methods of axial-view analysis of the cilia, high-speed microcinématography, and step voltage-clamp. Rising depolarization (from 3 mV to 7ge; 30mV) increased the rate of beating from zero to maximally 58 Hz. During cyclic activity, the axis of the beat cone of a proximal segment of the cirrus was inclined by 60° (0° = perpendicular to cell surface), and was always oriented 90° counterclockwise to the power stroke. With the stimulus amplitude rising, the orientations of the power stroke and inclination were increasingly shifted in more counterclockwise directions by up to 80° After correction for inclination ( = normalization), and following planification of the track of the segment, we determined the following properties of the cycle during depolarization: The course of the cycle tended to be rounded, i.e., the ratio of major over minor amplitudes (= spatial polarity) approximated a value of 1.6 which is only two thirds of maximal spatial polarity observed during hyperpolarization. The angular velocity generally increased with rising steps of depolarization; up to +5 mV (and comparable to hyperpolarization-induced responses), the velocity maximum occurred during the return stroke. With depolarizations ≥7 mV the angular velocity maximum shifted to the power stroke so that the temporal polarity (rates of power stroke over rates of return stroke) increased from 0.4 to 1.6. Calculations of the angular velocity as referred to the proximal ciliary segment level suggest active sliding rates (between 5 and 30 nm/ms) of identified pairs of doublet microtubules. Ciliary frequency is a function of the rate of reorientation of the cyclic track; this parameter, which corresponds to the rate of translocation of active sliding between pairs of doublets, grew with the amplitude of depolarization. Translocation rates were high during transitions between the beat phases (power stroke, return stroke), and were reduced during these phases. Orientational polarograms of the mean rates of both active sliding and sliding translocation show properties of discreteness as well as continuity. The depolarization-induced changes in inclination, and the inferred patterns of sliding rate and sliding translocation rate, are compared with previous results from hyperpolarization-dependent activation of the same motor organelle.
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    Outer-arm dynein from trout spermatozoa: Substructural organization (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 266-278 
    Details
    ISSN: 0886-1544
    Keywords: ATPase ; flagella ; intermediate chains ; vanadate-mediated photolysis ; vertebrate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Outer-arm dynein purified from trout spermatozoa was disrupted by low-ionicstrength dialysis, and the resulting subunits were separated by sucrose density-gradient centrifugation. The intact 19 S dynein, containing the α- an β-heavy chains, intermediate chains (ICs) 1-5 and light chains (LCs) 1-6, yielded several discrete particles: a 17.5 S adenosine triphosphatase (ATPase) composed of the γ-and β-chains ICs 3-5 and LC 1; a 9.5 S complex containing ICs 1 and 2 together with LCs 2, 3, 4, and 6; and a single light chain (LC 5), which sedimented at ∼4 S. In some experiments, ICs 3-5 also separated from the heavy chain complex and were obtained as a distinct subunit. Further dissociation of the 17.5 S particle yielded a 13.1 S ATPase that contained the β-heavy chain and ICs 3-5. The polypeptide compositions of the complexes provide new information on the intermolecular associations that occur within dynein.Substructural features of the trout dynein polypeptides also were examined. The heavy chains were subjected to vanadate-mediated photolysis at the V1 sites by irradiation at 365 nm in the presence of Mg2+, ATP, and vanadate. Fragment pairs of relative molecular mass (Mr) 245,000/185,000 and 245,000/170,000 were obtained from the α- and β-heavy chains, respectively. Photolysis of these molecules at their V2 sites, by irradiation in the presence of vanadate and Mn2+, yielded fragments of Mr 160,000/270,000 and 165,000/250,000, respectively. These values confirm that the α- and β-heavy chains have masses of 430,000 and 415,000 daltons, respectively.Immunological analysis using monoclonal antibodies revealed that one intermediate chain from trout dynein (IC 2) contains epitopes present in two different intermediate chains from Chlamydomonas dynein. This indicates that specific sequences within the dynein intermediate chains have been highly conserved throughout evolution.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990) 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970170101
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    Dynamic microvillar cytoskeletons in arthropod and squid photoreceptors (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 1-5 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Tension as a regulator and integrator of axonal growth (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 6-10 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Quantitative relationships between single-cell and cell-population model parameters for chemosensory migration responses of alveolar macrophages to C5a (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 279-293 
    Details
    ISSN: 0886-1544
    Keywords: Cell motility ; chemotaxis ; mathematical model ; alveolar macrophages ; C5a ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Phenomenological parameters from a mathematical model of cell motility [1] are used to quantitatively characterize chemosensory migration responses of rat alveolar macrophages migrating to C5a in the linear under-agarose assay, simultaneously at the levels of both single cells and cell populations. This model provides theoretical relationships between single-cell and cell-population motility parameters. Our experiments offer a critical test of these theoretical linking relationships, by comparison of results obtained at the cell population level to results obtained at the single-cell level.Random motility of a cell population is characterized by the random motility coefficient, μ (analogous to a particle diffusion coefficient), whereas single-cell random motility is described by cell speed, s, and persistence time, P (related to the period of time that a cell moves in one direction before changing direction). Population chemotaxis is quantified by the chemotactic sensitivity, χo, which provides a measure of the minimum attractant gradient necessary to elicit a specified chemotactic response. Single-cell chemotaxis is characterized by the chemotactic index, CI, which ranges from 0 for purely random motility to 1 for perfectly directed motility. Measurements of cell number versus migration distance were analyzed in conjunction with the phenomenological model to determine the population parameters while paths of individual cells in the same experiment were analyzed in order to determine the single-cell parameters.The parameter μ shows a biphasic dependence on C5a concentration with a maximum of 1.9 × 10-8 cm2/sec at 10-11 M C5a and relative minima of 0.86 × 10-8 cm2/sec at 10-7 M C5a and 1.1 × 10-8 cm2/sec in the absence of C5a; s and P remain fairly constant with C5a concentration, with s ranging from 2.1 to 2.5 μm/min and P varying from 22 to 32 min. χo is equal to 1.0 × 10-6 cm/receptor for all C5a concentrations tested, corresponding to 60% correct orientation for a difference of 500 bound C5a receptors across a 20 μm cell length. The maximum CI measured was 0.2.Values for the population parameters μ and χo were calculated from single-cell parameter values using the aforementioned theoretical linking relationships. The values of μ and χo calculated from single-cell parameters agreed with values of μ and χo determined independently from population migrations, over the full range of C5a concentrations, confirming the validity of the linking equations. Experimental confirmation of such relationships between single-cell and cell-population parameters has not previously been reported.
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    Immunocytochemical identification of cytoskeletal linkages to smooth muscle cell nuclei and mitochondria (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 11-18 
    Details
    ISSN: 0886-1544
    Keywords: intermediate filaments ; desmin ; cytoskeleton ; protein A-gold ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In avian smooth muscle cells, desmin-containing intermediate filaments (IFs) are a prominent component of the cytoskeleton and are readily seen in several domains, inclu-ding the axial intermediate filament bundle (IFB). Both the nucleus and some of the mitochondria are partly surrounded by elements of the IFB. By using anti-desmin and protein-A-colloidal gold labeling, we have identified intermediate filaments that form linkages with the nuclear envelope and with mitochondria. These linkage regions seem to occupy a proportionately greater part of the mitochondrial surface than of the nuclear envelope. The existence of these linkages in smooth muscle cells is consistent with results that support similar linkages to mitochondria and other cellular structures in various cells that contain either vimentin or keratin IFs. These linkages could functionally restrain or assist in homeostatically restoring organelles to their normal position after the rearrangement that accompanies the substantial shortening of smooth muscle cells.
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    Distribution of microtubules containing post-translationally modified α-tubulin during drosophila embryogenesis (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 34-45 
    Details
    ISSN: 0886-1544
    Keywords: detyrosinated α-tubulin ; Drosophila embryo ; confocal microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of microtubules (MTs) enriched in detyrosinated α-tubulin (Glu-tubulin) was studied in Drosophila embryos by immunofluorescence micro-scopy by using a monoclonal antibody (ID5) which was raised against a 14-residue synthetic peptide spanning the carboxyterminal sequence of Glu-tubulin (Wehland and Weber: J. Cell Sci. 88:185-203, 1987). While all MT arrays contained tyrosinated α-tubulin (Tyr-tubulin), MTs rich in Glu-tubulin were not found during early stages of development even by using an image intensification camera. Elevated levels of microtubular Glu-tubulin were first detected after CNS condensation in neurone processes. In addition, sperm tails, which remained remarkably stable inside the embryo until late stages of development, were decorated by ID5. This was in marked contrast to the distribution of microtubule arrays containing acetylated α-tubulin, which could already be detected during the cellular blastoderm stage. Additional experiments with taxol suggested that the absence of MTs rich in Glu-tubulin during early stages of development was not due to the rapid turnover rate of MTs, which would be too fast for α-tubulin to be detyrosinated. The possible significance of the differential detyrosination and acetylation of microtubules during development is discussed.
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    Yeast myosin heavy chain mutant: Maintenance of the cell type specific budding pattern and the normal deposition of chitin and cell wall components requires an intact myosin heavy chain gene (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 301-308 
    Details
    ISSN: 0886-1544
    Keywords: yeast ; myosin ; budding ; cell wall ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Recent studies with myosin heavy chain mutants in the slime mold Dictyostelium discoideum and the yeast Saccharoymyces cerevisiae indicate that the myosin heavy chain gene is not essential for cell survival under laboratory growth conditions. However, cells lacking a normal myosin heavy chain gene demonstrate substantial alterations in growth and cell division. In this study, we report that a disruption mutant in the rod portion of the yeast myosin heavy chain gene, MYOl, produces abnormal chitin distribution and cell wall organization at the mother-bud neck in a high proportion of dividing cells. It is suggested that this phenotype is the cause of the cell division defect and the osmotic sensitivity of yeast MYOl mutants. In the absence of a normal MYOl polypeptide, yeast cells alter their cell type specific budding pattern. It is concluded that an intact myosin heavy chain gene is required to maintain the cell type specific budding pattern and the correct localization and deposition of chitin and cell wall components during cell growth and division.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970150401
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    Tau protein: An update on structure and function (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 199-203 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Molecular characterization of high molecular weight microtubule-associated proteins: Some answers, many questions (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 204-209 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Nucleotide specificity for the bidirectional transport of membrane-bounded organelles in isolated axoplasm (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 210-219 
    Details
    ISSN: 0886-1544
    Keywords: organelle motors ; nucleoside triphosphates ; fast axonal transport ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Video microscopy of isolated axoplasm from the squid giant axon permits correlated quantitative analyses of membrane-bounded organelle transport both in the intact axoplasm and along individual microtubules. As a result, the effects of experimental manipulations on both anterograde and retrograde movements of membrane-bounded organelles can be evaluated under nearly physiological conditions. Since anterograde and retrograde fast axonal transport are similar but distinct cellular processes, a systematic biochemical analysis is important for a further understanding of the molecular mechanisms for each. In this series of experiments, we employed isolated axoplasm of the squid to define the nucleoside triphosphate specificity for bidirectional organelle motility in the axon. Perfusion of axoplasm with 2-20 mM ATP preserved optimal vesicle velocities in both the anterograde and retrograde directions. Organelle velocities decreased to 〈50% of optimal values when the axoplasm was perfused with 10-20 mM UTP, GTP, ITP, or CTP with simultaneous depletion of endogenous ATP with hexokinase. Under the same conditions, TTP and ATP-γ-S were unable to support significant levels of transport. None of the NTPs tested had a differential effect on anterograde vs. retrograde movement of vesicles. Surprisingly, several inconsistencies were revealed when a comparison was made between these results and nucleoside triphosphate specificities that have been reported for putative organelle motors by using in vitro assays. These data may be used in conjunction with data from well-defined in vitro assays to develop models for the molecular mechanisms of axonal transport.
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    Identification of an amino acid substitution in the benA, β-tubulin gene of Aspergillus nidulans that confers thiabendazole resistance and benomyl supersensitivity (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 87-94 
    Details
    ISSN: 0886-1544
    Keywords: benzimidazole ; anti-microtubule agents ; carbendazim ; nocodazole ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We are using molecular genetic techniques to identify sites of interaction β-tubulin with benzimidizole anti-microtubule agents. We have developed a marker-rescue technique for cloning mutant alleles of the benA, β-tubulin gene of Aspergillus nidulans and have used the technique to clone two mutant benA alleles, benA16 and benA19. These are the only A. nidulans alleles known to confer resistance to the benzimidazole antimicrotubule agent thiabendazole and supersensitivity to other benzimidazole antimicrotubule agents including benomyl and its active breakdown product, carbendazim. benA16 has been shown, moreover, to reduce thiabendazole binding to β-tubulin. We have sequenced the two mutant alleles and have found that they carry different nucleotide changes that cause the same single amino acid substitution, valine for alanine at amino acid 165. Since thiabendazole and carbendazim differ at only one side chain, the R2 group, we conclude that the region around amino acid 165 is involved in the binding of the R2 group of benzimidazole antimicrotubule agents to β-tubulin.
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    Neurite elongation is blocked if microtubule polymerization is inhibited in PC12 cells (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 95-105 
    Details
    ISSN: 0886-1544
    Keywords: colchicine-tubulin ; neurite growth ; process extension ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have injected process-bearing PC12 cells with colchicine-tubulin mixed with either fluorescein-dextran or a rhodamine-labelled tubulin analogue to determine the role of microtubule polymerization in neurite elongation. Colchicine-tubulin is a specific, substoichiometric poison of microtubule assembly. We have shown that colchicine-tubulin does not cause existing PC12 microtubules to disassemble, and yet can inhibit the assembly of rhodamine-tubulin injected along with it. In population s'udies of neurite outgrowth in injected and uninjected cells, we find that colchicine-tubulin substantially inhibits neurite extension from injected cells over a wide variety of concentrations. In acute time-course studies of injected cells, we find that colchicine-tubulin does not block neurite outgrowth until the injectate reaches the neurite tip. Thereafter, however, it blocks process elongation completely. Thus we can conclude that microtubule polymerization in the region of the growth cone is an important element in neurite elongation. While polymerization at the cell body may be important in supplying subunits to the distal neurite, it does not play a direct role in process extension.
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    Transmembrane cytoskeletal modulation in preterminal growing axons: I. Arrest of bulk and organelle transport in goldfish retinal ganglion cell axons regenerating in vitro by lectins binding to sialoglycoconjugates (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 106-117 
    Details
    ISSN: 0886-1544
    Keywords: Wheat germ agglutinin ; Limax flavus agglutinin ; axonal cytoskeleton ; actin ; cytochalasin D ; axoplasmic transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Goldfish retinal ganglion cell (RGC) axons regenerating in vitro exhibit a novel mode of axoplasmic transport that entails a rapid bidirectional bulk redistribution of axoplasm, “packaged” as protruding varicosities and non-protruding phase-dense inclusions (Koenig et al.: J. Neurosci. 5:715-729, 1985; Edmonds and Koenig Brain Res. 406:288-293, 1987). We have used phase-contrast video microscopy to study transmembrane effects of surface-binding lectins on bulk transport and transport of single visible organelles in RGC axons. Our findings show that certain lectins which crosslink sialoglycoconjugates, such as wheat germ agglutinin (WGA) and the more specific sialic acid-binding lectin Limax flavus agglutinin (LFA), induce a rapid inhibition of transport activity. The LFA-induced inhibition of transport can be reversed by appropriate simple sugar haptens, and can also be antagonized by pretreatment with cytochalasin D. One of the consequences of LFA binding is an increase in RITC-conjugated phalloidin fluorescence staining of preterminal axons. The latter observation in conjunction with the antagonistic action of cytochalasin D suggests that one possible explanation for the transmembrane arrest of transport induced by crosslinking of surface sialoglycoconjugates may involve a polymerization and/or reorganization of the actin filament network which hinders translocation of mobile axoplasmic components.
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    Announcement (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 142-142 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970170209
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    Functional diversity of dyneins (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 147-149 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970170302
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    Stoichiometry of estramustine phosphate binding to MAP2 measured by the disassembly of chick brain MAP2: Tubulin microtubules (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 167-173 
    Details
    ISSN: 0886-1544
    Keywords: microtubule disassembly ; tubulin-binding sites ; protein concentration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The concentration of estramustine phosphate required to inhibit the assembly or to induce the disassembly of chick brain MAP2:tubulin microtubules is markedly dependent upon the microtubule protein concentration. Analysis of this relationship shows that estramustine phosphate and tubulin compete for common MAP2 sites, that MAP2 can bind 5-6 moles-mole-1 estramustine phosphate, and that the Kd of these sites is ≏ 20 μM estramustine phosphate. It is proposed that two molecules of estramustine phosphate interact with each of the three tubulin-binding sites of MAP2 and inhibit the MAP2:tubulin interaction by neutralising two highly conserved basic residues.
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    Dynamic properties of intermediate filaments: Disassembly and reassembly during mitosis in baby hamster kidney cells (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 150-166 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeletal dynamics ; IF depolymerization ; type III IF regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphological analysis of the organizational changes in the type III intermediate filament (IF) system in dividing baby hamster kidney (BHK-21) cells was carried out by immunofluorescence and immunoelectron microscopy. The most dramatic change occurred during prometaphase, when the typical network of long 10-nm-diameter IF characteristic of interphase cells disassembled into aggregates containing short 4-6 nm filaments. During anaphase-telophase, arrays of short IF reappeared throughout the cytoplasm, and, in cytokinesis, the majority of IF were longer and concentrated in a juxtanuclear cap. These results demonstrate that the relatively stable IF cytoskeletal system of interphase cells is partitioned into daughter cells during mitosis by a process of disassembly and reassembly. This latter process occurs in a series of morphologically distinct steps at different stages of the mitotic process.
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    Effect of filamin and controlled linear shear on the microheterogeneity of F-Actin/Gelsolin gels (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 236-249 
    Details
    ISSN: 0886-1544
    Keywords: bundles ; cytomechanics ; photobleaching ; rheology ; viscoelasticity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously established [Cortese and Frieden, J. Cell Biol. 107:1477-1487, 1988] that actin gels formed under shear are microheterogeneous. In this study, the effect of cross-linking (by chicken gizzard filamin), severing (by plasma gelsolin), and shear on actin microheterogeneity are investigated using fluorescence photobleaching recovery and video microscopy. We find that filamin and shear form microheterogeneous F-actin:gelsolin gels by different mechanisms. Bundling of actin:gelsolin filaments by filamin can be explained by an increase in the apparent length of the filaments due to interfilament binding, resulting in a decrease of the polymer number concentration at which filaments organize into anisotropic phases. Some intrafilament binding of filamin to actin filaments may also be present, and those filaments coated with filamin immobilize more slowly than actin under the same polymerization conditions. The length of F-actin/gelsolin filaments seems to be a major factor in controlling the extent of bundling relative to network formation. In contrast, the effect of shear on the microheterogeneity of actin:gelsolin filaments is consistent with our previous proposal that shear aligns actin filaments, allowing filament-filament interactions and phase formation to occur. Short filaments are unable to organize into branched actin networks, but they can create large aggregates under low shear. Longer actin filaments will exist as networks with variable levels of branching and are less sensitive to shear. The effect of the intensity of a shear field on the spatial distribution of actin may involve a progressively more random orientation of actin molecules and bundles. A regular pattern develops across the sample at low shear rates (0.04-1.39 s-1), and becomes very irregular at higher shear rates (〉 10 s-1). We suggest here that actin-binding proteins and shear can control the transition between isotropic networks and anisotropic phases by their effect on apparent length and local filament concentration, and also that this transition can have substantial effects on the resistance of cells to mechanical stress.
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    Ultrastructural cytoskeleton alterations and modification of actin expression in the NIH/3T3 cell line after transformation with Ha-ras-Activated oncogene (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 220-229 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoskeleton alterations of NIH/3T3 fibroblast monolayers transfected with Haras-activated oncogene were studied by immunofluorescence, immunoelectron microscopy, and immunoelectrophoretic analysis of actin isoforms. Transformation foci were found to consist of cells with a round shape and rare stress fibers that spread sparsely, forming rare focal contacts and fibronexuses. The loss of stress fibers in transformed cells was confirmed by staining with rhodamine-phalloidin and with a fluorescinated anti-non-muscle cell actin antibody. The transformed cells were anchored to the substrate prominently by filaments that contained fibronectin, as showed by immunoelectron microscopy. A down-regulation of α-actin isoform was observed by immunofluorescence and immunoblotting analysis using a specific monoclonal antibody. The diffuse distribution of α-actin, lacking a specific association with stress fibers, challenges the hypothesis of a connection between α-actin down-regulation and stress fiber loss.
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    Cytoskeletal dynamics in rabbit synovial fibroblasts: II. Reformation of stress fibers in cells rounded by treatment with collagenase-lnducing agents (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 121-132 
    Details
    ISSN: 0886-1544
    Keywords: microfilaments ; cytochalasin ; cell shape ; integrins ; intermediate filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Modulation of the synthesis and secretion of extracellular matrix proteins and matrix-degrading metalloproteases by rabbit synovial fibroblasts in an important model system for studying the control of tissue-specific gene expression. Induction of collagenase expression is correlated with changes in cell shape and actin filament distribution, but the role of the cellular cytoskeleton in the sustained synthesis and secretion of metalloproteases has not been closely examined. When cells were allowed to respread after rounding by trypsin or cytochalasin, two known metalloprotease inducers, reformation of stress fibers was observed within 2 h in the presence of serum. In the absence of serum, trypsin-treated cells did not respread substantially, even after 24 h in culture. In contrast, cytochalasin-treated cells recovered almost as rapidly in the absence as in the presence of serum, showing reformation of well-formed microfilament bundles within 30 min of drug removal, especially at the spreading cell edges. High resolution electron-microscopic views of detergent-extracted cytoskeletons confirmed the rapid rebundling of peripheral microfilaments. Acrylamide-treated cells fell between these two extremes, spreading slowly in the absence of serum, but almost as rapidly as cytochalasin-treated cells in its presence. Reestablishment of normal intermediate filament distribution generally lagged slightly behind actin for all treatments, and intermediate filaments always appeared to spread back into the cellular cytoplasm within the confines of the reforming peripheral microfilament bundles. No obvious interaction between these two cytoskeletal elements was observed after any treatment, and no specific role for intermediate filaments in modulating gene expression in these cells is suggested by these results. The serum dependence displayed after trypsin or acrylamide treatment may be due to the disturbances in fibronectin synthesis observed in these cells and is consistent with evidence that both induction and sustained expression of matrix-degrading metalloprotease may involve signals transduced through plasma membrane matrix receptors (integrins).
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    The cytoskeletal system of mammalian primitive erythrocytes: Studies in developing marsupials (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 133-145 
    Details
    ISSN: 0886-1544
    Keywords: marsupials ; mammals ; primitive erythrocytes ; nucleated erythrocytes ; marginal bands ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Seeking to resolve conflicting literature on cytoskeletal structure in mammalian “primitive” generation erythrocytes, we have utilized the circulating blood of developing marsupials. In young of the Tammar Wallaby (Macropus eugenii) and the Gray Short-tailed Opossum (Monodelphis domestica), relatively large, nucleated primitive erythrocytes constituted nearly 100% of the circulating population of birth (= day 0) and in fetuses (Tammar) several days before birth. These cells were discoidal or elliptical, and flattened except for a nuclear bulge. Their cytoskeletal system, consisting of a marginal band of microtubules enclosed within a cell surface-associated network (membrane skeleton), closely resembled that of non-mammalian vertebrate erythocytes. By day 2 or 3, much smaller anucleate erythrocytes of “definitive” morphology, lacking marginal bands, appeared in abundance. These accounted for 〉90% of the circulating population of both species by day 6-8. Non-nucleated erythrocytes of a different type, constituting 1-6% of the cells in most blood samples up to day 7, were identified as anucleate primitives on the basis of size, shape, and presence of a marginal band. Thus, loss of erythrocyte nuclei in mammals appears to begin earlier than generally recognized, i.e., in the primitive generation. Counts of these anucleate primitives in young of various ages implicated nucleated primitives as their probable source. Pointed erythrocytes, occasionally found in younger neonates of both species, occurred in greatest number in fetuses (Tammar) prior to birth. This is in accord with previous work on non-mammalian vertebrates suggesting that such cells are morphogenetic intermediates. The results confirm the long-suspected similarity between mammalian primitive erythrocytes and the nucleated erythrocytes of all non-mammalian vertebrates.
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    T-1, a mitotic arrester, alters centrosome configurations in fertilized sea urchin eggs (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 146-154 
    Details
    ISSN: 0886-1544
    Keywords: sea urchin ; centrosome ; immunofluorescence microscopy ; barrel-shaped spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: T-1 induces modifications in the shape of the centrosome at division in fertilized eggs of the North American sea urchin, Lytechinus pictus. Phase contrast microscopy observations of mitotic apparatus isolated from T-1treated (1.7-8.5μM) eggs at first division shows that the centrosomes already begin to spread or to separate by prophase and that the mitotic spindle is barrel-shaped. When eggs are fertilized with sperm that have been pretreated with T-1, the centrosomes become flattened; the spindles are of normal length. Immunofluorescence microscopy using an anti-centrosomal monoclonal antibody reveals that T-l modifies the structure of the centrosome so that barrel-shaped spindles with broad centrosomes are observed at metaphase, rather than the expected focused poles and fusiform spindle. Higher concentrations of T-l induce fragmentation of centrosomes, causing abnormal accumulation of microtubules in polar regions. These results indicate that T-l directly alters centrosomal configuration from a compact structure to a flattened or a spread structure. T-l can be classified as a new category of mitotic drugs that may prove valuable in dissecting the molecular nature of centrosomes.
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    Talin: Role at sites of cell-substratum adhesion (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 7-13 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970160103
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    Light chains of sea urchin kinesin identified by immunoadsorption (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 204-213 
    Details
    ISSN: 0886-1544
    Keywords: kinesin ; molecular structure ; immunoaffinity purification ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies with monoclonal antibodies indicate that sea urchin kinesin contains two heavy chains arranged in parallel such that their N-terminal ends fold into globular mechanochemical heads attached to a thin stalk ending in a bipartitetail [Scholey et al. 1989]. In the present, complementary study, we have used the monoclonal antikinesin. SUK4, to probe the quaternary structure of sea urchin (Strongylocentrotus purpuratus) kinesin. Kinesin prepared from sea urchin cyto-sol sedimented at 9.6 S on sucrose density gradients and consisted of 130-kd heavy chains plus an 84-kd/78 kd doublet (1 mol heavy chain: 1 mol doublet determined by gel densitomctry). Low levels of 110-kd and 90-kd polypeptides were sometimes present as well. The 84-kd/78 kd polypeptides are thought to be light chains because they were precipitated from the kinesin preparation at a stoichiometry of one mol doublet per 1 mol heavy chain using SUK4-Sepharose immunoaffinity resins. The 110-kd and 90-kd peptides, by contrast, were removed using this immunoadsorption method. SUK4-Sepharose immunoaffinity chromatography was also used to purify the 130-kd heavy chain and 84-kd/78-kd doublet (1 mol heavy chain: 1 mol doublet) directly from sea urchin egg cytosolic extracts, and from a MAP (microtubule-associated protein) fraction eluted by ATP from microtubules prepared in the presence of AMPPNP but not from microtubules prepared in ATP. The finding that sea urchin kinesin contains equi-molar quantities of heavy und light chains, together with the aforementioned data on kinesin morphology, suggests that native sea urchin kinesin is a tetramer assembled from two light chains and two heavy chains.
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    Differential effects of gelsolins on tissue culture cells (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 229-238 
    Details
    ISSN: 0886-1544
    Keywords: microinjection ; actin cytoskeleton ; degradation of stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gelsolins, prepared from a number of different sources, showed similar severing activity on F-actin in vitro or on stress fibers of detergent-extracted cells but differed in their effects on actin in stress fibers of microinjected cells. When human gelsolin isolated from plasma was injected into cells in a Ca++-containing buffer, stress fibers were degraded, the cellular morphology was changed, and numerous actin patches appeared. These effects were particularly striking when the Ca++-insensitive N-terminal proteolytic fragment of this gelsolin was injected. By contrast, Ca++-sensitive gelsolins isolated from human platelets, pig stomach smooth muscle and pig plasma showed no comparable activity. Furthermore, the Ca++-independent N-terminal proteolytic fragments prepared from these gelsolins also had no effect despite their in vitro actin severing activity. Most striking was the finding that human plasma gelsolin expressed in E. coli did not degrade stress fibers, in contrast to the same protein isolated from plasma; nor was there any stress fiber disruption observed with the N-terminal half of human gelsolin expressed in Escherichia coli.The different behavior of these gelsolins in cells cannot be explained by sequence diversity between plasma and cytoplasmic forms, nor by variability in the Ca++ sensitivity of the preparations. It suggests the presence of factors, as yet unidentified, that may regulate gelsolin activity in the cytoplasm of living cells and discriminate between gelsolins of different origin. Such discrimination could be achieved as a result of post-translational modification of the gelsolin; only in this way can differences between apparently identical proteins isolated from human plasma and expressed in E. coli be reconciled.
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    In vitro induction of crawling in the amoeboid sperm of the nematode parasite, Ascaris suum (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 99-110 
    Details
    ISSN: 0886-1544
    Keywords: ascaris ; nematode ; nematoda ; sperm ; amoeboid motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a highly synchronous process, the immotile spermatids of Ascaris suum extend pseudopods and become rapidly crawling sperm when treated with an extract from the glandular vas deferens of the male under strict anaerobic conditions. Within 9-12. min, a pseudopod develops, elongates rapidly, and exhibits a continuous flow of membrane specializations, the villipodia, from tip toward base. When attached to acid-washed glass, the pseudopod pulls the cell body along at speeds exceeding 70 μm/min. The pseudopod length remains constant while retrograde flow of villipodia proceeds at the same rate as the sperm's forward movement. Cohorts of about 15 villipodia form at the leading edge, move reaward together, and disappear at the junction of pseudopod and cell body. These are the termination of branched, refringent fibers, which extend the length of the pseudopod. The latter are the fiber complexes that form its cytoskeleton (Sepsenwol et al.: Journal of Cell Biology 108:55-66, 1989). Locomoting cells sometimes change direction when another crawls by and follow each other. When cells are exposed to air, forward movement ceases in a predictable pattern: the forward extension of the leading edge ceases, the pseudopod shortens from the base, and the cell body continues to be pulled forward. These data contribute to a model for Ascaris sperm amoeboid motility in which independent processes of continuous extension at the leading edge and continuous shortening at the base of the pseudopod act to propel the cell forward.
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    Keratin filaments restrict organelle migration into the forming spindle of newt pneumocytes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 111-120 
    Details
    ISSN: 0886-1544
    Keywords: prometaphase ; mitosis ; intermediate filaments ; video microscopy ; high-voltage electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When viewed by light microscopy the mitotic spindle of newt pneumocytes appears to assemble in an optically clear area of cytoplasm, virtually devoid of mitochondria and other organelles, which is often much larger than the spindle. This clear area is also frequently larger than the region previously occupied by the nucleus. It forms even in prometaphase cells depleted of microtubules prior to nuclear envelope breakdown by colchicine treatment. Time-lapse video microscopy reveals that as prometaphase proceeds this clear area slowly and progressively collapses around the forming spindle so that it is greatly diminished or nonexistent by the onset of anaphase. The sharply defined nature of the boundary between the clear area and the remaining cytoplasm and the fact that organelles accumulate at its periphery suggest that a structural barrier is present at the boundary that limits organelle migration into the forming spindle. Immunofluo- rescence and electron microscopy, of cells previously followed in the living state, reveal that the periphery of the clear area contains prominent bundles of keratin filaments but lacks microtubules and actin. From our observations we conclude that keratin filaments form a loosely organized cage that surrounds the forming newt pneumocyte spindle. We propose that this cage functions, in part, to restrict the dispersion of chromosomes during nuclear envelope breakdown and to impede the bulk migration of organelles into the forming spindle.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970150301
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    Clathrin-coated membrane: A distinct membrane domain in acetylcholine receptor clusters of rat myotubes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 121-134 
    Details
    ISSN: 0886-1544
    Keywords: clathrin ; cell-substrate adhesion ; freeze fracture ; quick-freeze ; deep-etch ; rotary- replication ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have used antibodies to clathrin light chains in immunocytochemical studies of acetylcholine receptor (AChR) clusters of cultured rat myotubes. Immunofluorescence and ultrastructural experiments show that clathrin is present in coated pits and in large plaques of coated membrane. Coated membrane plaques are spatially and structurally distinct from AChR-rich membrane domains and the bundles of microfilaments that are also present in AChR clusters. Clusters contain a relatively constant amount of clathrin light chain protein, which is not dependent on the amount of AChR. Clathrin plaques remain after AChR domains are disrupted by azide, or after microfilament bundles are destabilized by cytochalasin D. Extraction of myotubes with saponin removes clathrin without disrupting AChR domains. Thus, clathrin plaques, microfilament bundles, and AChR-rich domains are independently stabilized.
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    Actin-dependent carotenoid droplet dispersion in permeabilized cultured goldfish xanthophores (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 139-146 
    Details
    ISSN: 0886-1544
    Keywords: organelle translocation ; cytosolic factor ; secretion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Organelle translocations are essential cellular processes. Although much progress has been made with regards to microtubule-dependent organelle translocations, little is known about actin-dependent organelle translocation(s) except cytoplasmic streaming in Nitella. On the other hand, there is indirect evidence that actindependent organelle translocation may be involved in secretion. We now present evidence that the dispersion of the pigment organelles carotenoid droplets in goldfish xanthophores is apparently actin dependent and that this process may be related to secretory processes. We show that, in digitonin-permeabilized goldfish xanthophores, the pigment organelles can be induced to disperse by a combination of cAMP, ATP, and xanthophore cytosol. This induced dispersion is inhibited by DNase I, phalloidin, or anti-actin, but not by anti-tubulin or anti-intermediate filament proteins, suggesting a dependence on F-actin. Since the dispersion of carotenoid droplets and secretion both involve outward translocation of organelles, we tested the possibility that cytosols of secretory tissues have similar activity. Such activity was indeed found in different tissues, apparently in parallel with the secretory activity of the tissues, suggesting that pigment dispersion in xanthophores and some secretory processes may share a common component.
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    Identification and characterization of a novel mammalian intermediate filament-associated protein (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 19-33 
    Details
    ISSN: 0886-1544
    Keywords: HeLa cells ; microtubule-associated proteins ; MAPIA ; vimentin filaments ; cytokeratin filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A novel monoclonal antibody, designated M1.4, recognizes the high molecular weight microtubule-associated protein MAPIA (ca. Mr 380 kD) in both bovine and rat brain. In HeLa cells, however, M1.4 binds to a 240 kD polypeptide on immunoblots and co-localizes with both vimentin and cytokeratin filaments using double-label immunofluorescence microscopy. Immunoelectron microscopy indicates that the 240 kD polypeptide localizes along bundled intermediate filaments in a periodic manner. Two-dimensional electrophoretic analysis indicates that the 240 kD polypeptide has a basic pI of 7.7. When HeLa cell intermediate filaments are isolated using standard non-ionic detergent/high-salt conditions the 240 kD polypeptide does not sediment with the intermediate filaments, unlike the established intermediate filament-associated protein plectin. Immunoblot analysis with M1.4 shows the 240 kD polypeptide is expressed in a number of mammalian cell lines. Additionally, double-label immunofluorescence shows the 240 kD polypeptide to associate with vimentin filaments in African Green Monkey kidney (CV-1) and JC neuroblastoma cells. Due to its unique biochemical and biological characteristics, the 240 kD polypeptide is clearly a novel intermediate filament-associated protein for which we have proposed the designation gyronemin (Gr.gyros: around: nemin: filament).
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970170301
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    The expression and posttranslational modification of a neuron-specific β-tubulin isotype during chick embryogenesis (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 118-132 
    Details
    ISSN: 0886-1544
    Keywords: tubulin heterogeneity ; neural differentiation ; neuronal microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five β-tubulin isotypes are expressed differentially during chicken brain development. One of these isotypes is encoded by the gene cβ4 and has been assigned to an isotypic family designated as Class III (βIII). In the nervous system of higher vertebrates, βIII is synthesized exclusively by neurons. A βIII-specific monoclonal antibody was used to determine when during chick embryogenesis cβ4 is expressed, the cellular localization of βIII, and the number of charge variants (isoforms) into which βIII can be resolved by isoelectric focusing. On Western blots, βIII is first detectable at stages 12-13. Thereafter, the relative abundance of βIII in brain increases steadily, apparently in conjunction with the rate of neural differentiation. The isotype was not detectable in non-neural tissue extracts from older embryos (days 10-14) and hatchlings. Western blots of protein separated by two-dimensional gel electrophoresis (2D-PAGE) reveal that the number of βIII isoforms increases from one to three during neural development. This evidence indicates that βIII is a substrate for developmentally regulated, multiple-site posttranslational modification. Immunocytochemical studies reveal that while cβ4 expression is restricted predominantly to the nervous system, it is transiently expressed in some embryonic structures. More importantly, in the nervous system, immunoreactive cells were located primarily in the non-proliferative marginal zone of the neural epithelia. Regions containing primarily mitotic neuroblasts were virtually unstained. This localization pattern indicates that cβ4 expression occurs either during or immediately following terminal mitosis, and suggests that βIII may have a unique role during early neuronal differentiation and neurite outgrowth.
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    Reorganization of circumferential microfilament bundles in retinal epithelial cells during mitosis (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 133-141 
    Details
    ISSN: 0886-1544
    Keywords: contractile ring ; cytoskeleton ; cell division ; cytokinesis ; zonula adhaerens ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To examine the behaviour of the apical circumferential microfilament bundles (CMBs) associated with the zonula adhaerens (ZA)-junctions during mitosis, retinal pigment epithelial cells were labelled for F-actin, and retinas were serially sectioned for TEM. The results show that the ZA-CMB-complex persists throughout all stages of mitosis. At metaphase, the cells round up, but stay joined apically to adjacent cells by ZA-junctions. At telophase, the cleavage furrow forms asymmetrically from the basal end progressively toward the apical end, where the daughter cells remain connected by an intercellular bridge (IB). As the cleavage furrow with the contractile ring (CR) approaches the CMB, the two microfilament (MF) systems are oriented perpendicularly to each other. At the level of the CMB, the MFs of the CR connect the opposite sides of the CMB and bisect it into two CMBs, one for each of the two daughter cells. Subsequently, the CR in the IB splits into two, one on either side of the midbody. The two daughter cells, having acquired a complete CMB of their own, do not become direct neighbours, since adjacent cells, which remain joined to the apical ZA-junction of the dividing cell, are observed in the cleavage furrow, where they meet and form a ZA-junction between themselves, just below the IB. Separation of the daughter cells without losing contact with neighbouring cells at the level of the apical ZA-junction thus maintains the integrity of the epithelial sheet during mitosis.
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    Microtubule-associated proteins from antarctic fishes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 174-186 
    Details
    ISSN: 0886-1544
    Keywords: MAPs ; cold-stable microtubules ; microtubule assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubules and presumptive microtubule-associated proteins (MAPs) were isolated from the brain tissues of four Antarctic fishes (Notothenia gibberifrons, N. coriiceps neglecta, Chaenocephalus aceratus, and a Chionodraco sp.) by means of a taxol-dependent, microtubule-affinity procedure (cf. Vallee: Journal of Cell Biology 92:435-442, 1982). MAPs from these fishes were similar to each other in electrophoretic pattern. Prominent in each preparation were proteins in the molecular weight ranges 410,000-430,000, 220,000-280,000, 140,000-155,000, 85,000-95,000, 40,000-45,000, and 32,000-34,000. The surfaces of MAP-rich microtubules were decorated by numerous filamentous projections. Exposure to elevated ionic strength released the MAPs from the microtubules and also removed the filamentous projections. Addition of fish MAPs to subcritical concentrations of fish tubulins at 0-5°C, induced the assembly of microtubules. Both the rate and the extent of this assembly increased with increasing concentrations of the MAPs. Sedimentation revealed that approximately six proteins, with apparent molecular weights between 60,000 and 300,000, became incorporated into the microtubule polymer. Bovine MAPs promoted microtubule formation by fish tubulin at 2-5°C, and proteins corresponding to MAPs 1 and 2 co-sedimented with the polymer. MAPs from C. aceratus also enhanced the polymerization of bovine tubulin at 33°C, but the microtubules depolymerized at 0°C, We conclude that MAPs are part of the microtubules of Antarctic fishes, that these proteins promote microtubule assembly in much the same way as mammalian MAPs, and that they do not possess special capacities to promote microtubule assembly at low temperatures or to prevent cold-induced microtubule depolymerization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170305
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  • 98
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    Announcement (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 271-272 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150409
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  • 99
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    Diffuse kinetochores and holokinetic anaphase chromatin movement during mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20 (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 245-259 
    Details
    ISSN: 0886-1544
    Keywords: polycentric chromosome ; light microscopy ; electron microscopy ; high-pressure freezing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20 was examined by light microscopy of living and fixed cells. During early prometaphase the numerous small (0.30-3.0-μm) chromosomes appear as discrete units that lack a primary constriction. However, by late prometaphase the chromosomes are tightly packed at the spindle equator and are no longer clearly resolvable as individuals. When viewed from the side the metaphase chromatin appears as a 2-3-μm wide band that spans the width of the spindle; when viewed from the pole it appears as a fenestrated disk. The metaphase chromatin splits at anaphase into two sister chromatin plates, each of which exhibits holokinetic poleward movement, i.e., all parts of each plate move as a single unit with the same velocity. In many early-to-mid anaphase cells the separating sister plates are connected by chromatin-containing bridges that break as anaphase progresses. Ultrastructural analyses of serial thick and thin sections from cells fixed by conventional, OsO4/KFeCN, or high pressure rapid freezing methods, reveal that by metaphase all of the chromosomes are interconnected to form a large, irregularly shaped fenestrated disk of chromatin. Similar analyses reveal that adjacent chromatids remain interconnected throughout anaphase. Each disk of metaphase and anaphase chromatin contains numerous kinetochores recessed within its polefacing surface. Kinetochores consist of a fine, faintly staining fibrillar material arranged along the chromatin surface as thin (0.1-0.3 μm dia.) rods varying considerably (0.15-2.3 μm) in length. From these observations we conclude that the polycentric metaphase chromatin of A. constricta, and its holokinetic behavior during anaphase, arises from the aggregation or cohesion of smaller prometaphase chromosomes, each of which contains a single, diffuse kinetochore.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150407
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  • 100
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    Actin and actin-binding proteins in yeast (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 7-11 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150103
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