Michael Parra - Academia.edu (original) (raw)
Papers by Michael Parra
Genes & Development, 1999
The mechanisms that couple cell cycle progression with the organization of the peripheral cytoske... more The mechanisms that couple cell cycle progression with the organization of the peripheral cytoskeleton are poorly understood. In Saccharomyces cerevisiae, the Swe1 protein has been shown previously to phosphorylate and inactivate the cyclin-dependent kinase, Cdc28, thereby delaying the onset of mitosis. The nim1-related protein kinase, Hsl1, induces entry into mitosis by negatively regulating Swe1. We have found that Hsl1 physically associates with the septin cytoskeleton in vivo and that Hsl1 kinase activity depends on proper septin function. Genetic analysis indicates that two additional Hsl1-related kinases, Kcc4 and Gin4, act redundantly with Hsl1 to regulate Swe1. Kcc4, like Hsl1 and Gin4, was found to localize to the bud neck in a septin-dependent fashion. Interestingly, hsl1 kcc4 gin4 triple mutants develop a cellular morphology extremely similar to that of septin mutants. Consistent with the idea that Hsl1, Kcc4, and Gin4 link entry into mitosis to proper septin organization, we find that septin mutants incubated at the restrictive temperature trigger a Swe1-dependent mitotic delay that is necessary to maintain cell viability. These results reveal for the first time how cells monitor the organization of their cytoskeleton and demonstrate the existence of a cell cycle checkpoint that responds to defects in the peripheral cytoskeleton. Moreover, Hsl1, Kcc4, and Gin4 have homologs in higher eukaryotes, suggesting that the regulation of Swe1/Wee1 by this class of kinases is highly conserved. ; FAX 432-6161. 176 GENES & DEVELOPMENT 13:176-187 © 1999 by Cold Spring Harbor Laboratory Press ISSN 0890-9369/99 $5.00; www.genesdev.org Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 177 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 183 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from
Se define como campo escalar a una función ϕ(, ,) x y z de la posición que le hace corresponder e... more Se define como campo escalar a una función ϕ(, ,) x y z de la posición que le hace corresponder en forma unívoca un escalar a cada punto de ese espacio. Campos escalares son la temperatura en un instante dado para una región espacial. También lo son la presión, la densidad, etc. para cada punto de una región en un instante definido. También se define al campo vectorial como la función A(, ,) xyz vectorial de la posición, que asigna en forma unívoca a cada punto del espacio una magnitud vectorial. Son conocidos como campos vectoriales el campo gravitatorio, el campo eléctrico y el magnético, el campo de velocidades de un fluido, etc.
Genes & Development, 1999
The mechanisms that couple cell cycle progression with the organization of the peripheral cytoske... more The mechanisms that couple cell cycle progression with the organization of the peripheral cytoskeleton are poorly understood. In Saccharomyces cerevisiae, the Swe1 protein has been shown previously to phosphorylate and inactivate the cyclin-dependent kinase, Cdc28, thereby delaying the onset of mitosis. The nim1-related protein kinase, Hsl1, induces entry into mitosis by negatively regulating Swe1. We have found that Hsl1 physically associates with the septin cytoskeleton in vivo and that Hsl1 kinase activity depends on proper septin function. Genetic analysis indicates that two additional Hsl1-related kinases, Kcc4 and Gin4, act redundantly with Hsl1 to regulate Swe1. Kcc4, like Hsl1 and Gin4, was found to localize to the bud neck in a septin-dependent fashion. Interestingly, hsl1 kcc4 gin4 triple mutants develop a cellular morphology extremely similar to that of septin mutants. Consistent with the idea that Hsl1, Kcc4, and Gin4 link entry into mitosis to proper septin organization, we find that septin mutants incubated at the restrictive temperature trigger a Swe1-dependent mitotic delay that is necessary to maintain cell viability. These results reveal for the first time how cells monitor the organization of their cytoskeleton and demonstrate the existence of a cell cycle checkpoint that responds to defects in the peripheral cytoskeleton. Moreover, Hsl1, Kcc4, and Gin4 have homologs in higher eukaryotes, suggesting that the regulation of Swe1/Wee1 by this class of kinases is highly conserved. ; FAX 432-6161. 176 GENES & DEVELOPMENT 13:176-187 © 1999 by Cold Spring Harbor Laboratory Press ISSN 0890-9369/99 $5.00; www.genesdev.org Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 177 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 183 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from
Se define como campo escalar a una función ϕ(, ,) x y z de la posición que le hace corresponder e... more Se define como campo escalar a una función ϕ(, ,) x y z de la posición que le hace corresponder en forma unívoca un escalar a cada punto de ese espacio. Campos escalares son la temperatura en un instante dado para una región espacial. También lo son la presión, la densidad, etc. para cada punto de una región en un instante definido. También se define al campo vectorial como la función A(, ,) xyz vectorial de la posición, que asigna en forma unívoca a cada punto del espacio una magnitud vectorial. Son conocidos como campos vectoriales el campo gravitatorio, el campo eléctrico y el magnético, el campo de velocidades de un fluido, etc.