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G Albrecht-Buehler

Publications and source records attributed to G Albrecht-Buehler.

At least 37 records · Page 2Linked to original sources
PubMed1986

Distribution of microfilament bundles during rotation of the nucleus in 3T3 cells treated with monensin.

Cytoskeletal aspects of monensin-treated 3T3 cells with rotating nuclei were studied by immunofluorescence. The pattern of intermediate filaments and microtubules appeared unchanged when compared with control cells having a stationary nucleus. In contrast, the actin microfilament bundles appeared to have a consistent distribution in cells with rotating nuclei. Typically, we did not find long microfilament bundles that traverse the length of the cytoplasm of cells that were fixed at the time of nuclear rotation. Instead, there was a local distribution of short microfilament bundles situated ventrally to the nucleus and oriented at various angles to one another and to the predominant distribution of microfilament bundles in the cell. The observations suggest that the actin cytoskeleton is reorganized locally before or during rotation of the nucleus.

Actin Cytoskeleton↗
PubMed1986

The degree of coupling of nuclear rotation in binucleate 3T3 cells.

In order to test the existence of mechanical coupling between the rotational movements of two adjacent nuclei, we prepared binucleate 3T3 cells and observed their nuclear movements by near infrared microscopy and recorded them with time-lapse video techniques. We found that 49 out of 110 (44%) of the selected binucleate cells expressed nuclear rotation. Rotation could occur in just one of the nuclei while the second nucleus remained stationary (31/110) or in both nuclei simultaneously (18/110). In almost all cases where both nuclei rotated simultaneously (15/110) they did so at different speeds and in opposite directions. The nuclei were observed to rotate in the same direction in only three of the examples. The results are consistent with a weak mechanical interaction between a rotating nucleus and its neighbor. Consistent with our previous observations in mononucleate cells, we did not find a characteristic position of the centrosphere or a special distribution of the microtubules or the intermediate filaments in binucleate cells with rotating nuclei. There was an absence of long, well-formed microfilament bundles beneath the nuclei during rotation, even in the local region beneath the rotating nucleus in those cells with one rotating and one stationary nucleus. Also consistent with observations of mononucleate cells, nuclear rotation was inhibited by treatment with colcemid, although the ability of the nuclei to rotate was eventually restored when the colcemid-containing medium was replaced with normal medium.

Actin Cytoskeleton↗
PubMed1986

Light conductance in the ocular lens.

The collimated beam of a He-Ne laser aimed tangentially at the equator of submerged bovine or rabbit ocular lenses enters the lens and travels in the surface of the lens. We suggest that the effect is the result of light conductance along the interface between the bulk of the lens (including the lens epithelium on the anterior surface) as the medium of higher refractive index and the capsule as a medium of lower refractive index. Light conductance can be demonstrated in isolated lenses as well as in intact eyes. It is very sensitive to alterations of the state of the lens and therefore it may offer a new method to study very early stages of lens damage and cataract formation.

Animals↗
PubMed1986

The motile behavior of virus-transformed 3T3 cells.

Using metallic gold in various assays for the motility of cultured tissue cells, the paper compares the movements of surface projections and the locomotion of polyoma (Py3T3) and SV40 (SV3T3) virus-transformed 3T3 cells with the behavior of the parental 3T3 cells. The movement of surface projections was assayed by the ability of filopodia, lamellipodia and blebs of freshly plated cells to remove colloidal gold particles from a particle-coated glass substrate. The ability of filopodia to probe the environment for points of anchorage was tested by observing cells plated on glass whose filopodia touched the surface of a neighboring area of evaporated gold. The locomotion of cells was assayed by particle-free tracks (phagokinetic tracks) which were left by migrating cells on a glass substrate which was previously coated with colloidal gold particles. The paper suggests that the ability of the transformed cells to sense environmental factors, and their behavioral controls are altered.

Animals↗
PubMed1982

Control of tissue cell movement.

The cytoplasm of migrating animal cells appears to be composed of smaller, autonomously moving units (microplasts). Consequently, the mere act of displacement of a cell calls for the existence of communicating the strategy-issuing cell centers to guarantee cooperation between the autonomous parts. These centers appear to control cell migration in that they "steer" two sister cells along symmetrical or identical pathways. They lead a cell out of the collision with another at the same angle at which they collided and seem to communicate with control centers of other cells because cells can migrate directionally as groups. They even seem to collect spatial data as demonstrated by cells which followed a guiding line and arrived at the intersection between two such lines. There the cells appeared to probe all optional directions before choosing one. Thus the concept emerges that tissue cells are active data collecting and processing organisms. As a further consequence, the question has to be asked seriously whether aging the cancer, both of which appear to involve behavioral defects of cells, are related to reprogrammed control centers of cell movement.

Animals↗
PubMed1981

Does the geometric design of centrioles imply their function?

The paper suggests several principles of construction of a microscopically small device for locating the directions of signal sources in microscopic dimensions. It appears that the simplest and smallest device that is compatible with the scrambling influence of thermal fluctuations as are demonstrated by Brownian motion is a pair of cylinders oriented at right angles to each other. Nine equally spaced blades run in a pitched fashion along the mantle of each cylinder. The blades have a concave cross-section and bend around the circumference of the cylinder in a certain rotational pattern. Considering the striking similarity of this hypothetical device with centrioles, the paper puts forward the conjecture that centrioles locate the direction of hypothetical signals inside cells.

Animals↗
PubMed1980

Autonomous movements of cytoplasmic fragments.

Tiny fragments from the cytoplasm of human skin fibroblasts with about 2% of the original cell volume ("microplasts") were prepared by treatment with cytochalasin B, vigorous pipetting, and trypsinization of the attached fragments. They remained alive for 8 hr or longer. Some of the microplasts were able to produce and move filopodia, ruffle, or both; others blebbed continuously. Slow flattening was observed in the larger microplasts. In all cases tested, microplasts avoided contact with other cells or microplasts. The observations suggest that the cytoplasmic matrix and the membranes of animal cells are so constructed as to express locally and autonomously any one of the elementary amoeboid movements listed above. More importantly, whatever types of motile surface projections a microplast expressed, it continued to produce and move them in a stereotypical way as if there were long-lived structural or material determinants for each type. The microplasts were unable to locomote autonomously. Therefore, it is conceivable that directional movement of whole cells may require a supervising mechanism that confers a certain coordination and strategy on its component cytoplasmic bits. Otherwise they would continue to move in stereotypical and autonomous ways without ever displacing themselves, as suggested by the behavior of the microplasts.

Cell Movement↗
PubMed1979

The angular distribution of directional changes of guided 3T3 cells.

This paper reports that the angular distribution of directional change of 3T3 cells which followed guiding lines on a substrate and left the guidance at various angles shows a peculiar preference for angles between 30 degrees and 60 degrees. Regarding the phenomenon of cellular guidance itself, 3T3 cells faced with a choice between guiding lines toward different directions seem to explore various options before following one. This observation suggests that the outcome of a probing action and not substrate properties alone can explain the guidance behavior of 3T3 cells.

Cell Line↗
PubMed1977

The phagokinetic tracks of 3T3 cells.

This paper describes a technique of visualizing tracks of cultured cells moving on a glass substrate covered with gold particles. It leads to the following observations: -If the tracks of many cells are examined, cell line characteristic track patterns become apparent. -In several cases, second or third generation descendents of 3T3 cells were observed to repeat track patterns of their ancestor cell. -If a 3T3 cell collides with another 3T3 cell or a nonmigrating BSC-1 cell, it forms an outgoing track from the impact area as if the cell was elastically reflected at the target.

Animals↗
PubMed1977

Phagokinetic tracks of 3T3 cells: parallels between the orientation of track segments and of cellular structures which contain actin or tubulin.

Phagokinetic tracks were used to determine the current direction of migration in 3T3 cells. Comparing this direction with the orientation of actin or tubulin-containing cellular structures by indirect immunofluorescence, the following results were obtained. First, the main actin-containing bundles were located at the bottom and tail end of 3T3 cells and ran parallel to the current or preceding direction of migration. Second, the 3 micrometer long rod-like structure (primary cilium), which contains tubulin and which has been observed by other investigators in transmission electron microscopy (Barnes, 1961; Sorokin, 1962; Wheatley, 1969) and in indirect immunofluorescence (Osborn and Weber, 1976), was oriented predominantly parallel to the substrate and to the current movement direction. It seems possible that the primary cilium has a role in the directional control of a migrating 3T3 cell, and that the main actin containing bundles act as substrate-attached rails along which the nucleus and bulk cytoplasm slide during displacement of the cells.

Actins↗