Judith A. Snyder

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Metaphase and anaphase spindles in cultured newt and PtK1 cells were irradiated with a UV microbeam (285 nM), creating areas of reduced birefringence (ARBs) in 3 s that selectively either severed a few fibers or cut across the half spindle. In either case, the birefringence at the polewards edge of the ARB rapidly faded polewards, while it remained fairly(More)
Taxol, a microtubule stabilizing agent, has been used to study changes in spindle microtubule organization during mitosis. PtK1 cells have been treated with 5 micrograms/ml taxol for brief periods to determine its effect on spindle architecture. During prophase taxol induces microtubules to aggregate, particularly evident in the region between the nucleus(More)
The concentration dependent effects of griseofulvin (GF) on mitosis in PtK1 cells were studied using a combination of time lapse cinematography and polarization and electron microscopy. Low concentrations of GF (4×10−5 M) allowed a substantial number of cells to enter and complete an apparently normal mitosis. At higher concentrations of GF (1×10−4 M and(More)
The relationship between progression through anaphase and furrow establishment was investigated in PtK1 cells using the anti-mitotic agent Nocodazole to arrest cells at different points in anaphase. The capacity of cells to furrow was compared to the kinetochore-kinetochore separation attained at the time of arrest. For the stages of anaphase examined,(More)
The microtubule initiation capacity of the mitotic centrosome was studied in PtK1 cells by using the highly reversible microtubule inhibitor nocodazole. Cells blocked with nocodazole at any stage prior to onset of anaphase completed mitosis by reforming the spindle following release from the drug. Cells treated with nocodazole immediately upon onset of(More)
The enzymes of importance in moving chromosomes are called motor proteins and include dynein, kinesin, and possibly myosin II. These three molecules are all included in the category of ATPases, in that they have the ability to convert chemical energy into mechanical energy. Both dynein and kinesin have been documented as molecules that “walk” along(More)
Motor proteins play a fundamental role in the congression and segregation of chromosomes in mitosis as well as the formation of the mitotic spindle. In particular, the dynein/dynactin complex is involved in the maintenance of the spindle, formation of astral microtubules, chromosome motion, and chromosome segregation. Dynactin is a multisubunit, high(More)
Treatment of PtK1 cells during metaphase with solutions containing hyperosmotic concentrations of sucrose resulted in an alteration of kinetochore structure and function in a concentration-dependent manner. This alteration in kinetochore morphology was shown to be rapidly reversible upon removal of the sucrose-containing tissue culture medium. A 10-min(More)
In this study we extend our analysis of the effect of Cytochalasin J (CJ) on mitotic and interphase cells by the use of immunocytochemical techniques to localize antigens to anti-beta-tubulin, anti-dynein heavy chain (HC), anti-dynein intermediate chain (IC), and anti-kinesin antibodies following CJ treatment. Anti-dynein IC and HC staining of CJ treated(More)
Metaphase and anaphase PtK1 cells show spindle elongation without concomitant chromosome motion when treated with culture medium containing 0.5 M sucrose. Electron microscopy has shown sucrose-induced changes in microtubule (MT) organization, changes in trilaminar kinetochore structure, and specific kinetochore-MT associations which may account for these(More)