摘要:

AbstractWe describe a simple method for direct visualization of the velocity distribution of particles moving against an immobile background. The technique involves pseudostereoscopic viewing of image pairs separated by an appropriate time interval in a sequential recording of the subject. Under these conditions, the positive or negative parallax arising from particle motion results in the binocular image of a particle being perceived as raised or lowered relative to an immobile background plane depending on its direction of movement, and with the degree of perceived elevation being proportional to its speed. In effect, the binocular optic axis becomes a velocity (speed) axis under these conditions. The technique is illustrated with examples of image pair sequences showing fast axonal transport in lobster and squid axons using video‐enhanced differential interference contrast microscopy. However, the pseudostereoscopic method is quite generally applicable to both microscopic and macroscopic time‐dependent phenomena. Particle speeds can be quantitated using standard procedures for measuring frame‐to‐frame particle displacements, or alternatively, by determination of parallax using stereogrammatic methods. It should be also readily adaptable for on‐line monitoring of particle velocity distribution, particularly in video systems where frame buffers can be utilized to extract and present serial image pairs having any desired time separation from video‐tape

ISSN:0271-6585    

DOI:10.1002/cm.970040402

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

年代:1984

数据来源: WILEY

摘要:

AbstractWe present observations on the relative location of the centriole and keratin filament cap in motile PtK1 cells. Subconfluent cells were double labeled with anticentriole and antikeratin sera. These preparations revealed that the centriole is separate from, but neighboring, the keratin filament cap. Serial ultrathin sections confirm this observation. These observations are consistent with the idea that the microtubule organizing center and intermediate filament distribution center are not identical or concentric in PtK1 cells.

ISSN:0271-6585    

DOI:10.1002/cm.970040403

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

年代:1984

数据来源: WILEY

摘要:

AbstractTrifluoperazine (TFP), a drug that binds to Ca2+‐calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton‐extracted “models” of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body‐shape parameters. When living paramecia were incubated in a standard buffer containing 10 μM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the “barium dance”), but cells preincubated in TFP did not “dance.” Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces adecreasein the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin‐activated calcium pump in the cell membrane. Paramecia extracted with Triton X‐100 and reactivated to swim forward (7 ≥ pCa ≥ 6) were not affected by addition of up to 40 μM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa<6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca+‐sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postul

ISSN:0271-6585    

DOI:10.1002/cm.970040404

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

年代:1984

数据来源: WILEY

摘要:

AbstractSea urchin coelomocytes were used as a model system to investigate the distribution and role of microtubules and microfilaments in cell spreading and filopodial formation. By using immunoblot characterized antisera to tubulin and actin coupled with immunofluorescence techniques, cellular protrusions were seen to contain actin filaments but no microtubules. Cells depleted of MT's by cold and colcemid treatments could attach, spread, and transform to the filopodial morphology normally.

ISSN:0271-6585    

DOI:10.1002/cm.970040405

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

年代:1984

数据来源: WILEY

摘要:

AbstractSix mutants of Paramecium tetraurelia, which display altered axonemal responses to Ca++, are described. The mutants, designatedatalantas, are impaired in their ability to swim backward when stimulated by ions or heat; instead they spin very rapidly in one place. Three mutants,ataA1–3, are completely unable to swim backward. The three lines, however, can be distinguished from one another by their forward swimming velocities. The remaining three mutants are leaky.ataBswims backward briefly when stimulated, then stops and spins in place.ataCandataDare extremely leaky and only display the spinning phenotype at elevated temperatures. An electrophysiological analysis reveals that all six mutants have normal membrane properties, including the Ca++inward current under voltage clamp. When the membrane is disrupted so as to allow the axoneme free access to Ca++, wild‐type cells swim backward, but the mutants do not. These data indicate the site(s) of lesion in the mutants is in the axoneme or in some step linking Ca++influx and the axoneme, not within the ciliary membrane. These mutants may be useful in investigating the role of Ca++in the regulation of axonemal mot

ISSN:0271-6585    

DOI:10.1002/cm.970040406

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

年代:1984

数据来源: WILEY

摘要:

AbstractCultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+or carbamyl choline plus Ca2+. With video‐enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be see

ISSN:0271-6585    

DOI:10.1002/cm.970040407

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.970040408

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.970040401

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

年代:1984

数据来源: WILEY