摘要:

AbstractObservations on living mitoic cells have suggested that material in the spindle moves poleward during mitosis. In order to investigate this movement, sea urchin eggs have been microinjected with 0.25‐μm diameter carboxylated fluorescent beads. When fluorescent beads were injected into unfertilizedLytechinus variegatuseggs, no motility was detected. When injected into mitotic cells, beads moved to the spindle poles. Individual beads moved rapidly, in a saltory fashion, and followed generally linear paths. Beads appeared to move along astral fibers, were generally excluded from thespindle proper, and accumulated at the spindle poles. Some dispersion of the beads away from the pole was observed as cells completed mitosis, but the majority of beads retained a polar location. After depolymerization of spindle microtubules with nocodazole, some dispersion of beads into the cytoplasm was also observed. Beads moved along taxol‐induced astral microtubules and accumulated at astral centers. These observations reveal that negatively chargedbeads accumulate rapidly at mitotic centers, moving toward the minus end of the microtubules. Neither the bidirectional motility of similar beads in interphase cells nor the plus‐end‐directed bead motility seen in axons was observed in these mitot

ISSN:0886-1544    

DOI:10.1002/cm.970080402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractWhen demembranted axonemes ofChlamydomonaswere reactivated with Mg ATP, the proportion of motile axonemes was significantly increased by the preence of either phosphodiesterase (PDE) or protein inhibitor of cAMP‐dependent kinase (PKI). The effect of PDE was cancelled by the addition of cAMP. These findings strongly suggest that the axoneme samples have endogenous cAMP, which can reduce the proportion of motile axonemes via phosphorylation. This inhibitory effect of cAMP onChlamydomonasaxonemes is opposite to its stimulatory effect on the axonemal motility in other organisms so far reported. PKI or PDE activated the motility motility either in the absence of Ca2+, when the axonemes beat with an asymmetric waveform, or in 10−5M Ca2+, when the axonemes beat with a symmetric waveform. This cAMP‐dependent regulation of motility was observed with the axonemes from which detergent‐soluble material had been removed, indicating that the proteins responsible for the regulation still remained in the axonemes. Preliminary in vitro phosphorylation stdies have implicated two polypetides as candidates for the target protein of cAMP‐dependent protein kinase: one with a molecular weight of 270 kD and the other with a much larger molecul

ISSN:0886-1544    

DOI:10.1002/cm.970080403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFour monoclonal antibodies were raised against polypetides present in a highsalt detergent‐insoluble fraction from cells ofChlamydomonas reinhardtii. Indirect immunofluorescence microscopy of fibroblasts and epithelial cells grown in culture using these plant antibodies revealed staining arrays identical to those obtained with well characterised antibodies to animal intermediate filaments. Immunoflurescence microscopy ofChlamydomonaswith these monoclonal antibodies and a monoclonal antibody that recognises all animal intermediate filaments (anti‐IFA) gave a diffuse, patchy cytoplasmic staining pattern. Both the plant antibodies and anti‐IFA stained interphase onion root tip cells in a diffuse perinuclear pattern. In metaphase through to telophase, the labelling patterns colocalised with those of microtubules. Labelling of the phragmoplast was also detected but not staining of the preprophase band. On Western blots of various animal cell lines and tissues, all the antibodies labelled known intermediate filament proteins. On Western blots of wholeChlamydomonasproteins, all the antiboides labelled a broad band in the 57,000 Mrrange, and three antibodies labelled bands around 66,000 and 140,000 Mrbut with varibale intensites. On Western blots of whole onion root tip proteins, all the antibodies labelled 50,0000 Mr(two to three bands) polypetides and a diffuse and around 60,000 Mrand three of the antibodies also labelled several polypeptides in the 90,000–200,000 Mrrange. The consistent labelling of these different bands by several different monoclonal antibodies recognising animal intermediate filaments makes these polypetides putative plant intermediate filament p

ISSN:0886-1544    

DOI:10.1002/cm.970080404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractRat sperm from the cauda epididymis exhibit increased motility, longevity, and a distinct circular pattern of flagellar curvature in response to 5 mM procaine‐HCI or 0.1 mM 8‐(N, N‐diethylamino)‐octyl‐3,4,5‐trimethoxybenzoate (TMB‐8), reagents that are thought to play a role in the immobilization of free cellular calcium. Triton X‐100‐extracted sperm models will exhibit the same pattern of motility and curvature as procaine‐ or TMB‐8‐activated cells, but only when calcium is removed by a strong chelating agent, and in the pesence of cAMP (3 μM). Demembranated sperm models produced from epididymal rat sperm are quiescent unless cAMP is added. In these sperm models, the presence or absence of free calcium mediates a transition in flagellar curvature. The increased activity of the procaine‐treated intact cells was not accompained by a change in cellular ATP content, nor was ATP availability the limiting factor in the quiescent sperm. Therefore, the increased motility produced by procaine is probably mediated by a fall in free intracellular Ca2+accompained by a rise in cAMP. Our finding that calcium controls the curvature of sperm flagella may explain altered patterns of flagellar beating, such as the hyperactivated motility that sperm exhibit in the

ISSN:0886-1544    

DOI:10.1002/cm.970080405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractImmature oviduct implants from quails stimulated by estrogen to induce ciliogenesis were submitted to the in vitro action of benzodiazepines in organotypic culture. Diazepam and medazepam were added to the culture medium for 24 or 48 hours and tissues were examined by transmission and scanning electron microscopy for alterations in ciliary differentiation.Ciliogenesis was inhibited by both diazepam and medazepam, which affected mainly the migration of the basal bodies. Assembly of basal bodies was achieved normally in the cytoplasm, but their separation from generative complexes and migration toward the apical membrane were prevented. They remained in clusters around a deuteosome or eventually anchored to the close lateral plasma membrane.Furthermore, the drugs affected mature beating cilia, which then appeared lying tangentially to the cell surface. Relation between basal bodies and cortical cytoskeleton seemed to be altered by the drugs, which implies that the bearing of cilia and probably the ciliary beating movement were modified. Mocrovillus development was also altered by the action of these drugs.

ISSN:0886-1544    

DOI:10.1002/cm.970080406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis study report the first development of a fluorescently labeled filamin. Smooth muscle was labeled with fluorscent dyes in order to study its interaction with stress fibers and myofibrils, both in living cells and in permeabilized cells. The labeled filamin bounds to the Z bands of isolated cross‐striated myofibrils and to the Z bands and intercalated discs in both permeabilized embryonic cardiac myocytes and in frozen sections of adult rat venticle. In permeabilized embryonic chick myotubes, filamin bound to early myotubes but was absent at later stages. In living embryonic chick myotubes, the fluorescently labeled filamin was incorporated into the Z bands of myofibirls during early and late stages of develoment but was absent during an intermediate stages. In living cardiac myocytes, filamin‐IAR was incorporated into nascent as well as fully formed sarcomeres throughout develoment. In permeabilized nonmuslce cells, labeled filamin bound to attachment plaques and foci of polygonal networks and to the dense bodies in stress fibers. The periodic bands of filamin in stress fibers had a longer spacing in fibroblasts than in epithelial cells. When injected into living cells, filamin was readily incorporated into stress fibers in a striated pattern. The fluorescent filamin bands were broader in injected cells, however, than they were in permeabilized cells. We have interpreted these results from living and permeabilized cells to mean that native filamin is distributed along the full lengh of the actin filaments in the stress fibers, with a higher concentration present in the dense bodies. A sarcomeric model is presented indicating the position of filamin with respect to other proteins in the stress fib

ISSN:0886-1544    

DOI:10.1002/cm.970080407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAn autoantibody that binds an antigen localized to the stembody of dividing cells has been identified in a patient with systemic sclerosis. Initially, this antigen is associated with the surface of the metaphase chromosomes. At the onset of anaphase the antigen becomes preferentially associated with the forming stembodies. This association is maintained as furrowing progresses during telophase and continues after the intercellular bridge is released from the daughter cells during G‐1. Immunoblots indicate that the epitope detected by immunoflurorescence is present on a protein with an apparent molecular weight of 38 k

ISSN:0886-1544    

DOI:10.1002/cm.970080408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe Brookhaven scanning transmission electron microscpe (STEM) was used to elucidate the structures and masses of 12S and 19S dynein extracted from bull sperm flagella. The 12S particle was a single globular particle with an average mass of 311 ± 10 kdaltons. The 19S dynein particles consisted of two globular heads joined to a common base. The average mass of the 19S particle was 1.6 ± 0.04 × 106daltons. Thus, with the exception of the larger mass, the bull sperm 19S dynein molecule resembles the two‐headed 21S dynein obtained from sea urchin sperm flagella and the 18S dynein obtained fromChlamydomonaswith the possibility of a third head giving rise to the 12S particle. The structure, mass and polypeptide composition of bull sperm flagella dynein is compared with outer arm dyneins previously obtained fromChlamydomonas,Tetrahymena, and sea urchin sperm flag

ISSN:0886-1544    

DOI:10.1002/cm.970080409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe flagellar movement of intact ejaculated ram sperm, and of demembranated models reactivated with ATP, has been studied using high‐speed, high‐resolution video microscopy.Intact sperm attached to the coverslip by their heads had an average beat frequency of 20.9 Hz and an average wave amplitude of 20.2 μm. There was little difference in the beat frequency or waveform of these sperm and sperm swimming freely near the coverslip or captured by their heads with a micropipette and held far from the coverslip, inducationg that the flagellar waveform of ram sperm is relatively resistant to distorition as a result of immobilization of the head or proximity to a surface. The beat envelope was nearly planar as determined by observations of free‐swimming sperm and sperm captured by their head and oriented so they were beating either parallel or perpendicular to the plane of focus.The effect of various conditions for demembranation and reactivation of the sperm were examined. Treatment of sperm with 0.2 % Triton X‐100 removed most of their plasma membrane. Under optimal conditions, nearly 100 % of the demembranted sperm reactivated at MgATP2−concentrations ranging from ∼4 μM to ∼20 mM. From ∼ 1 mM to ∼ 10 mM MgATP2−, their beat pattern closely resembled that of intact sperm; beat frequency depended on MgATP2−concentration. Percent motility was maximal between pH 7.5 and 8.0 and decreased sharply below pH 7.0 and avove pH 8.5. The addition of 50 μM cAMP to the reactivation medium had no effect on percent motility or the beat pattern and did not accelerate th

ISSN:0886-1544    

DOI:10.1002/cm.970080410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0886-1544    

DOI:10.1002/cm.970080401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY