ISSN:0886-1544    

DOI:10.1002/cm.970060102

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

年代:1986

数据来源: WILEY

摘要:

AbstractCytoskeletal inhibitors were used as probes to test the involvement of microtubules and actin microfilaments in the development, motility, and shape maintenance of the pseudopodial networks (i e, reticulopodia) of the foraminifers Allogromia sp strain NF and Allogromia laticcllaris. Agents that disassemble cytoplasmic microtubules (cold, colchicine, and nocodazole) arrest all movement but have variable effects on reticulopodial shape. Electron microscopy reveals a granulofibrillar matrix but few, if any, microtubules in these motility‐arrested reticulopods. Allogromiids treated with cytochalasin B or D lose substrate adhesion and undergo dramatic changes in shape and motile behavior, highlighted by the coalescence of reticulopodial cytoplasm into irregularly shaped bodies with chaotic motility. Serial semithick sections of such preparations, viewed by high‐voltage electron microscopy, document a striking rearrangement of microtubules within these cytochalasin‐induced bodies. All aspects of cytochalasin‐altered motility are completely inhibited by colchicine. Actin is present in reticulopodia, as determined by staining with rhodamine‐phalloidin; this staining is not observed in cytochalasin‐treated organisms. These data provide compelling evidence that microtubules are required for reticulopodial motility. An actin‐based cytoskeleton is thought to play a role in maintaining shape, mediating pseudopod/substrate adhesion, and coordinating the various microtubule‐depe

ISSN:0886-1544    

DOI:10.1002/cm.970060103

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe distribution and motility of cytoplasmic particles was examined in PtK1 cells in which intermediate filament networks had been disrupted by acrylamide. In these cells, particles (mitochondria and vesicles) accumulated near the cell center although saltatory movements continued. This left a broad sheet of agranular cytoplasm at the periphery of the cell. Particles were capable of movement into this sheet. Intermediate filaments were absent in the peripheral cytoplasm although microtubules remained in a normal configuration. Particles apparently move along the microtubules. These results indicate that particle movement along microtubules is not dependent upon the normal configuration of intermediate filaments. It is suggested that intermediate filaments are necessary for normal organelle distribution and serve as a matrix with which particles can associate to maintain position.

ISSN:0886-1544    

DOI:10.1002/cm.970060104

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

年代:1986

数据来源: WILEY

摘要:

AbstractMilligram amounts of mammalian ciliary axonemes were isolated from porcine tracheas. These were reactivated upon addition of ATP, indicating intact functional capability with a mean beat frequency at 37°C of 8.2 Hz. Electron microscopy showed typical ultrastructure of the isolated demembranated axonemes. Electrophoresis into polyacrylamide gradient gels containing sodium dodecyl sulfate revealed reproducible protein profiles from ten different tracheal preparations. Four major protein bands were observed in the 300–330 K molecular weight region, as well as tubulin at 51–54K. Extraction of the isolated tracheal axonemes with 0.6M KCl removed the outer dynein arms seen in electron microscopic cross‐section of axonemes, preferentially solubilized two of the high molecular weight proteins at 320 and 330 K, and resulted in a three‐ to four‐fold increase in ATPase specific activity. Sedimentation of the dialyzed salt extract on a 5–30% sucrose density gradient and subsequent fractionation yielded two peaks of ATPase activity. The faster migrating, 19S major ATPase peak correlated with the 320 and 330 K proteins, and two other proteins at 81 and 67 K. The slower sedimenting, 12S minor ATPase peak corresponded to a 308 K protein and two smaller proteins at 33 and 48 K. Thus, the outer dynein arm of tracheal cilia appeared to be associated with at least two high molecular weight proteins. These results demonstrate that adequate quantities of functionally intact axonemes can be reproducibly isolated from porcine tracheas, allowing further fractionation and analysis of mam

ISSN:0886-1544    

DOI:10.1002/cm.970060105

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

年代:1986

数据来源: WILEY

摘要:

AbstractDuring hyphal tip growth in the fungus Basidiobolus magnus, nuclei normally maintain a constant distance from the advancing cell apex by continuously migrating forward. It is not known whether the mechanism that produces nuclear movement also mediates nuclear positioning, or whether these two processes are under separate control. By irradiating small cytoplasmic regions with an ultraviolet microbeam, the coordination between movement and positioning could be disrupted. Regardless of the distance of the target from the nucleus, anterior irradiations (those ahead of the nucleus) caused the nucleus to stop or move backwards, whereas posterior (behind the nucleus) irradiations caused an acceleration in the nuclear velocity. The nucleus retained its ability to move following irradiation, so there was only loss of control over normal positioning. These results suggest that movement and positioning are mediated by different mechanisms. Quantitative microtubule analysis demonstrated that microtubules in the target region had been depolymerized, but in other regions of the cell they were apparently normal. We suggest that the depolymerization of microtubules affects nuclear movement by altering the tensile strength of the cytoplasm, and that cytoskeletal tension mediate nuclear positioning.We also found that accelerated nuclear movement could occur when most of the microtubules surrounding the nucleus were depolymerized. A comparison of the microtubule population surrounding the nucleus in unirradiated versus irradiated cells suggested that microtubules move with nuclei. Therefore, the nucleus does not appear to move via a direct interaction with microtubules.

ISSN:0886-1544    

DOI:10.1002/cm.970060106

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

年代:1986

数据来源: WILEY

摘要:

AbstractVinculin was purified from chicken gizzard by a modification of the method of Feramisco and Burridge [1980; J Biol Chem 255:1194]. Vinculin did not alter the viscosity of actin as measured in an Ostwald viscometer, nor did it affect actin polymerization as measured with the fluorescent NBD‐actin assay. Sedimentation experiments demonstrated that vinculin did not bind to actin, and electron microscopy of negatively stained specimens indicated that vinculin did not aggregate actin filaments into bundles. These results suggest that vinculin, by itself, does not interact with actin at least under commonly used conditions to assay actin‐protein interactions in vi

ISSN:0886-1544    

DOI:10.1002/cm.970060107

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

年代:1986

数据来源: WILEY

摘要:

AbstractBasal bodies from laying quail oviduct were semipurified and used as immunogen to produce monoclonal antibodies. On 38 clones obtained and among those staining the apical pole of the ciliated cell, CC‐310 was chosen because it labeled the apical region with a punctated aspect, suggesting a staining of basal bodies or of basal body‐associated structures; the basal pole was also labeled.The ultrastructural localization performed by the immunogold technique showed that the labeling was mainly associated with the striated rootlets. The basal feet, the side of the basal bodies, and the basal poles of the demembranated cells were also decorated. The identification of the antigen performed by immunoblots of deciliated cortices revealed two proteins of 175,000 and 40,000, whereas immunoblots of basal bodies showed only the 175,000‐mw protein. The possibility of these two proteins sharing the same epitope, located at both poles of the cell, is discussed.Immunofluorescence ascertained that CC‐310 decorated the striated rootlets in ciliated epithelia from other species: mussel, frog, and human tissue. Finally, when tested on cultured cell lines, CC‐310 labeled the centrosome and its associated rootlets on PtK2 during interphase. During mitosis the poles of the mitotic spindle were stained without any apparent rootlet‐lik

ISSN:0886-1544    

DOI:10.1002/cm.970060108

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe spermatozoa from four infertile patients showing a flagellar dyskinesia due to abnormal flagellar wave development have been studied by light and transmission electron microscopy (TEM) for flagellar morphology. No axonemal anomalies were found but modification of the periaxonemal structures was observed. The results of a stereological analysis revealed abnormal extension of the individual dense fibres along the axoneme in the four cases as compared with a control group. The order of termination of those structures was therefore altered. However, the overall fibre extension was the same in both groups (ie, 60% of the principal piece). The number and the location of the longitudinal columns were also modified, the predominant anomaly being the presence of a single column. The possible influence of those structural anomalies on the pattern of sperm movement is discussed. Our observations seem to agree with a previous hypothesis of the literature, that the dense fibres might play a role in flagellar flexibility. More particularly, we suggest that the abnormal extension of dense fibres No. 2, 3, and 4 and the symmetric distribution of the dense fibres on both sides of the plane of beating may alter the flagellar curvature amplitude and the cell rotation frequency.

ISSN:0886-1544    

DOI:10.1002/cm.970060109

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

年代:1986

数据来源: WILEY

ISSN:0886-1544    

DOI:10.1002/cm.970060101

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

年代:1986

数据来源: WILEY