Multicopy suppression analysis of an anaphase defect in Saccharomyces cerevisiae.
Item
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Title
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Multicopy suppression analysis of an anaphase defect in Saccharomyces cerevisiae.
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Identifier
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AAI3024838
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identifier
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3024838
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Creator
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Steinberg-Neifach, Olga.
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Contributor
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Adviser: Dan Eshel
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Cell
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Abstract
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The kinesin-related Cin8p and cytoplasmic dynein are microtubule-associated motor proteins required for anaphase spindle elongation in the yeast Saccharomyces cerevisiae. Cells deleted for DYN1 (the gene encoding the dynein heavy chain) and carrying the temperature-sensitive allele cin8-3 can not grow at the temperatures above 35°C. Here, we report that the temperature sensitivity of haploid cin8-3 dyn1-Delta cells is suppressed by simultaneous presence of the MATa and MATalpha loci, which contain the regulatory genes that determine mating type. The presence of the two MAT loci also renders mutant and wild type haploid cells more resistant to the antimicrotubule drug benomyl. Since an introduction of the benomyl-resistant tub2-402 allele was also able to partially suppress the temperature sensitivity of cin8-3 dyn1-Delta, we concluded that suppression of the cin8-3 dyn1-Delta anaphase defect by simultaneous expression of MATa and MATalpha in the haploid cell occurs through a pathway that leads to an increase in microtubule stability. To further investigate effect of heterozygocity in the MAT locus on stability and functions of microtubules, we compared stability and functioning of microtubules in MAT a/MATalpha and MATa/ MATa wild type diploid cells. We found that homozygocity in MAT locus decreases stability of both cytoplasmic and nuclear microtubules. Decrease in microtubule stability leads to wider range of nuclear migration, cytokinesis delay and decrease in fidelity of chromosomal segregation in MATa/MAT a as compared to MATa/MATalpha diploid cells. Our results suggest that expression of both MAT loci in a single cell initiate a pathway that ultimately results in an increase of microtubule stability, which in diploid cells facilitates fidelity of chromosome segregation.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
