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E Unger

Publications and source records attributed to E Unger.

At least 127 records · Page 7Linked to original sources
PubMed1984

Effect of microtubule-associated proteins on the protofilament number of microtubules assembled in vitro.

In order to demonstrate the effect of microtubule-associated proteins on the protofilament number of microtubules, we used different systems of microtubule formation in vitro in which these proteins are either functionally eliminated (by DNA or glycerol) or absent (purified tubulin). The results obtained by electron microscopy of ultrathin-sectioned material indicate that under standard conditions in the presence of microtubule-associated proteins microtubules are formed consisting predominantly of 14 protofilaments. In cases of deficiency of microtubule-associated proteins, the mean value of the protofilament number is lower, and the protofilament number within the microtubule population varies remarkably. On the other hand, the action of microtubule-associated proteins is enhanced by histones resulting in increased protofilament numbers. A model is proposed illustrating that the quality and the quantity of microtubule-associated proteins bound to microtubules determine the curvature between the protofilaments and restrict the variety of their binding angles. In this way the microtubule-associated proteins may be regarded as an important factor in determining the structural fidelity of microtubules.

Animals↗
PubMed1984

Location of actin, myosin, and microtubular structures during directed locomotion of Dictyostelium amebae.

During their life cycle, amebae of the cellular slime mould Dictyostelium discoideum aggregate to form multicellular structures in which differentiation takes place. Aggregation depends upon the release of chemotactic signals of 3',5'-cAMP from aggregation centers. In response to the signals, aggregating amebae elongate, actively more toward the attractive source, and may be easily identified from the other cells because of their polarized appearance. To examine the role of cytoskeletal components during ameboid locomotion, immunofluorescence microscopy with antibodies to actin, myosin, and to a microtubule-associated component was used. In addition, rhodamine-labeled phallotoxin was employed. Actin and myosin display a rather uniform distribution in rounded unstretched cells. In polarized locomoting cells, actin fluorescence (due to both labeled phallotoxin and specific antibody) is prevalently concentrated in the anterior pseudopod while myosin fluorescence appears to be excluded from the pseudopod. Similarly, microtubules in locomoting cells are excluded from the leading pseudopod. The cell nucleus is attached to the microtubule network by way of a nucleus-associated organelle serving as a microtubule-organizing center and seems to be maintained in a rather fixed position by the microtubules. These findings, together with available morphological and biochemical evidences, are consistent with a mechanism in which polymerized actin is moved into the pseudopod through its interaction with myosin at the base of the pseudopod. Microtubules, apparently, do not actively participate in movement but seem to behave as anchorage structures for the nucleus and possibly other cytoplasmic organelles.

Actins↗
PubMed1984

Histological examination of the effect of various fractionated irradiations on transplanted mouse tumours. III. Observations with solid Ehrlich carcinoma.

Comparing the histological effects of differently fractionated X-ray irradiations of the same total dose it may be observed that the relatively higher fractions of radiation given in 3 to 4 days intervals caused in the early periods more severe damage in solid Ehrlich carcinoma than daily given less fractions. The daily several times given ultra-fractionation has no increased histologically detectable tumour damaging effect on this tumour.

Animals↗
PubMed1984

Histological examination of the effect of differently fractionated irradiations in rat and mouse organs. III. Autoradiographic examination of DNA synthesizing cells in locally X-irradiated rat spleens.

The spleen of rats was irradiated with 50 Gy dose local X-rays in two different fractionation rhythms, i.e. twice a week given high and daily applied lower fractions of radiation. According to the results of 3H-thymidine autoradiography made after the last irradiation 24 hours later both in the white and the red pulp the labelling index was less on the effect of twice in a week applied high radiation fractions than in case of daily given lower fractions. This indicate in correlation with the results of earlier analogous histological experiments that the damaging effect of rarely given higher fractions of radiation in the spleen is especially obvious.

Animals↗
PubMed1983

Histological examination of the effect of differently fractionated irradiations on transplanted mouse-tumours. II. Observations with Harding-Passey melanoma.

Comparing the histological effects of differently fractionated X-ray irradiations, using always the same total dose, it seems that Harding-Passey melanoma suffers in the early time points more severe damage by relatively high radiation fractions given with 3 to 4 day intervals than from daily applied smaller fractions of radiation. The daily several times given ultra-fractionation may promote the tumour destroying effect of X-ray irradiation from some points of view.

Animals↗
PubMed1982

Effect of microtubule inhibitors on the tubulin system of Dictyostelium discoideum.

Indirect immunofluorescence with antibodies to microtubular proteins has been used to investigate the microtubule system of Dictyostelium discoideum vegetative amoebae and the action of several compounds that interfere with that system. All the inhibitors tested show an antimicrotubular effect. Colchicine, vinblastine, nocodazole, thiabendazole, and isopropyl-N-phenyl-carbamate (IPC) seem to act mainly by destroying microtubules leaving the appearance of nuclei associated organelles (NAOs) undisturbed. On the other hand griseofulvin also affects NAOs which disappear in treated cells.

Benzimidazoles↗
PubMed1982

Histological effects of low-dose-rate gamma-irradiation. IV. Enzyme-histochemical studies.

Regarding the effect of a 10-Gy (1000 rd) acute whole-body gamma-irradiation, significant enzyme activity changes were demonstrated in radiosensitive and less radiosensitive organs of rat by histochemical methods. After irradiation with the same dose, using low (0.0042 Gy/min) dose-rate, the histochemical differences are generally less and their normalization is more rapid. Results similar to those of earlier histological experiments indicate that in case of low-dose-rate irradiation, the regeneration of damaged cells and cell functions, respectively, is sooner starting and more rapidly progressing than with acute irradiation.

Animals↗
PubMed1981

[Immunofluorescent studies of the microtubular system in slime moulds].

Using indirect immunofluorescence the microtubule system of slime molds has been investigated with antitubulin- and anti-MAP-antibodies. An extended cytoplasmic microtubule (MT) network with nucleus associated organells as centres can be visualized. The spindle apparatus with some astral fibres, the central spindle and the spindle pole bodies is stained in mitotic cells. In slime molds like in higher eucaryots MTs are sensitive against cold and MT-poison treatment, the MTs are composed of tubulin and MAP's, and tubulin is cross reactive with pig brain tubulin.

Dictyostelium↗
PubMed1981

Histological examination of the effect of differently fractionated irradiations in rat and mouse organs. I. Observations after 60Co-gamma whole-body irradiation.

After 60Co-gamma whole-body irradiation with a total dose of 4 Gy, fractionated in different manners, radiation injury is less after five fractions given daily than after two fractions given in 3-day intervals. This can histologically be shown on radiosensitive organs of rats and mice in some significant minority of the cases. After daily three, altogether 15 radiation fractions, only rarely can be observed further tissue sparing effect.

Animals↗