摘要:

AbstractThe Chlamydomonas flagellar surface exhibits interesting adhesive properties that are associated with flagellar surface motility. This dynamic surface property can be exhibited as the binding and movement of small polystyrene microspheres or as the interaction of the flagellar surface with a solid substrate followed by whole cell locomotion, termed “gliding.” In order to identify flagellar surface proteins that mediate substrate interaction during flagellar surface motility, two immobilized iodination systems were employed that mimic the conditions for flagellar surface motility: small polystyrene microspheres derivatized with lactoperoxidase, and large glass beads derivatized with Iodogen. Use of these iodination conditions resulted in preferential iodination of a high‐molecular‐weight glycoprotein with apparent molecular weight of 300,000–350,000. These results suggest this glycoprotein as a major candidate for the surface‐exposed adhesive component that directly interacts with the substrate and couples the substrate to a system of force transduction presumed to be located within th

ISSN:0271-6585    

DOI:10.1002/cm.970040202

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

年代:1984

数据来源: WILEY

摘要:

AbstractIn living tissue, membrane‐bound organelles, including mitochondria, move along parallel cytoplasmic pathways. Motion is directed and tends to be confined to a single path. Deviations from this single path motion are rare. When present, however, they tend to occur at points of intersection of cytoskeletal linear elements (LE). Such intersections are relatively uncommon in intact axons and extruded axoplasm. However, we have found that such intersections can be produced in extruded preparations by shear forces directed tangential to the axoplasmic surface.We have studied the detailed behavior of mitochondria in extruded squid axoplasm. Special attention was directed to the relationship between mitochondrial shape changes and orientation of cytoskeletal LE. The most striking of these changes in shape is branching. In this process, the mitochondrion transiently assumes a triradial (three‐ended) shape. This appearance may be maintained for seconds to minutes before the normal cylindrical shape is resumed by absorption of either the newly formed end or, more commonly, one of the original ends. The frequency of branching appears to be dependent on the degree of cytoskeletal organization. It becomes more common as the number of apparent intersections between cytoskeletal LE increases. Further, the formation of new ends seems to occur along paths defined by cytoskeletal elements.These observations suggest that the mitochondrial membrane is multivalent. That is, it contains multiple sites capable of interacting with the axonal force generation apparatus. Furthermore, LE in the cytoskeleton may indicate the paths along which these interactions are permissi

ISSN:0271-6585    

DOI:10.1002/cm.970040203

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

年代:1984

数据来源: WILEY

摘要:

AbstractHuman IgM and a bovine, IgM‐enriched serum fraction isolated from normal adult serum at concentrations of 0.25–1 mg/ml protein induced a pronounced increase in the metachronal wavelength of the lateral (L) cilia of the sea mussel Mytilus edulis without altering their beat frequency. This change in activity was indistinguishable from that induced by 50% adult human or bovine serum. At protein concentrations ranging from 1–9 mg/ml, human IgG or a bovine, IgG‐enriched serum fraction had no or little effect on the activity of the L cilia. Similarly, neither monomeric (8S) human IgM (0.25 mg/ml) nor monospecific pentameric IgM (1 mg/ml) isolated from Waldenström's macroglobulinemia patients altered the metachrony of the L cilia. Indirect immunofluorescence demonstrated that both bovine and human IgM became attached almost exclusively to the L cilia, while very little bovine or human IgG was found to associate with these cilia.The results of this study suggest that serum IgM specifically binds to the L cilia of Mytilus in an antigen–antibody manner and agglutinates adjacent cilia into blocks or bundles, thereby increasing the coupling between cilia. As a result, the wavelength of the metachronal coordination is increased. The origin of these ciliary antibodies and their significance to ciliary bioassays used to monitor serum for the detection of cystic fibrosis are

ISSN:0271-6585    

DOI:10.1002/cm.970040204

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

年代:1984

数据来源: WILEY

摘要:

AbstractIn a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 μM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP–PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein‐like ATPase, rather than a myosin, is involved in fast axonal trans

ISSN:0271-6585    

DOI:10.1002/cm.970040205

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

年代:1984

数据来源: WILEY

摘要:

AbstractLiving vegetative D. discoideum amoebae were studied to determine whether their filopodia respond to folic acid, a chemoattractant for these cells. Exponentially growing amoebae (ca. 10 μm diameter) exhibit 5–30 μm long filopodia; at stationary phase, aggregation competent amoebae have numerous multibranched filopodia up to 100 μm long. Folic acid was observed to stimulate production, elongation, and branching of filopodia with its effects progressively changing as the amoebae approach aggregation. Filopodial construction was also found to be dependent upon Mg2+levels. The significance of these results is discussed with respect to progressive changes within the vegetative phase as well as to the mechanisms of amoeboid movement, pseudopodial activity, and chemot

ISSN:0271-6585    

DOI:10.1002/cm.970040206

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

年代:1984

数据来源: WILEY

摘要:

AbstractFluorescent analogs of cellular components are finding increasing use in the field of cell biology. The power of this technique can be augmented by the use of antibodies specific for the fluorophore to visualize selectively the fluorescent analog at the electron microscope level. Rabbit antibodies specific for fluorescein were elicited and purified according to published methods (Lopatin and Voss [1971]: Biochemistry 10:208). Immune sera and IgG formed precipitin lines with fluorescein‐labeled proteins in Ouchterlony immunodiffusion assays, and significantly quenched the fluorescence of fluorescein‐labeled proteins. Immune IgG and Fab fragments decorated fluorescein‐labeled actin, but not unlabeled actin, in negative‐stained preparations. Anti‐fluorescein IgG was used for immunofluorescent localization of fluorescein‐labeled actin following microinjection of the fluorescent analog into living cells. This approach was extended to the immunoelectron microscopic localization of the injected analog at the subcellular level by the use of an electron‐dense marker coupled to goat anti‐rabbit IgG. Many other fluorescent probes also can be used as haptens for production of antibodies. Therefore, a general method for localizing fluorescently labeled molecules at the electron microscopic level is now available. Several other applications of anti‐fluorescein antibody in studies involving fluorescent analogs a

ISSN:0271-6585    

DOI:10.1002/cm.970040207

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

年代:1984

数据来源: WILEY

ISSN:0271-6585    

DOI:10.1002/cm.970040208

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

年代:1984

数据来源: WILEY

ISSN:0271-6585    

DOI:10.1002/cm.970040201

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

年代:1984

数据来源: WILEY