Video Experimental Relacionado
Updated: Jun 18, 2026
08:40
Determination of S-Phase Duration Using 5-Ethynyl-2'-deoxyuridine Incorporation in Saccharomyces cerevisiae
Published on: October 21, 2022
Iniciación prematura de la mitosis en levaduras que carecen de RCC1 o de una GTPasa que interactúa
1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York 11724.
Cell
|July 26, 1991
Resumen
Un nuevo mutante de la levadura de fisión, pim1, inicia la mitosis antes de que se complete la replicación del ADN. La sobreexpresión del gen esencial spi1 rescata este defecto, revelando una nueva subclase de GTPasa involucrada en la coordinación del ciclo celular.
Área de la Ciencia:
- Biología celular Biología celular.
- Genética molecular La genética molecular.
- La bioquímica es la bioquímica.
Sus antecedentes:
- El ciclo celular asegura la progresión ordenada a través de la replicación del ADN y la mitosis.
- La regulación del ciclo celular implica complejos puntos de control moleculares y vías de señalización.
- El sistema de modelo de levadura de fisión es crucial para diseccionar los mecanismos de control del ciclo celular.
Objetivo del estudio:
- Para caracterizar un mutante de levadura de fisión con mitosis no acoplada y replicación del ADN.
- Para identificar genes involucrados en la regulación de la progresión del ciclo celular.
- Investigar la función de las nuevas GTPasas en la coordinación del ciclo celular.
Principales métodos:
- Aislamiento y caracterización del mutante de la levadura de fisión pim1.
- Análisis de la progresión del ciclo celular, la replicación del ADN y los eventos mitóticos.
- La clonación de genes, los estudios de sobreexpresión y el análisis de la interacción genética.
- Búsquedas de homología de secuencias y análisis filogenético de nuevas GTPasas.
Principales resultados:
- El mutante pim1 inicia la mitosis prematuramente, antes de la finalización de la fase S, independientemente de cdc25.
- pim1 codifica un homólogo de la proteína nuclear humana RCC1.
- La sobreexpresión de spi1, un nuevo gen esencial, rescata el fenotipo mutante pim1.
- spi1 y el TC4 humano definen una nueva subclase de GTPasas ras-como.
- La interrupción de la spi1 conduce a anomalías nucleares y a una haploidización mitótica de alta frecuencia.
Conclusiones:
- pim1 juega un papel en la coordinación de la replicación del ADN con la entrada mitótica.
- spi1 es esencial para la progresión del ciclo celular e interactúa con pim1.
- La subclase spi1/TC4 representa un grupo funcional distinto dentro de la superfamilia de las GTPasas.
- Estos hallazgos proporcionan nuevos conocimientos sobre los mecanismos moleculares que rigen el control del ciclo celular.
Videos de Conceptos Relacionados
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:15M-Cdk Drives Transition Into Mitosis
Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
02:17Separation of Sister Chromatids
At the transition from prophase to metaphase, there is a reduction in cohesion along the chromosomal arms, resulting in the resolution of sister chromatids. However, residual cohesin connections remain to hold the sister chromatids together until the transition from metaphase to anaphase. The residual connection prevents any premature separation of sister chromatids, blocking the risks of aneuploidy within the daughter cells.
At the onset of anaphase, separase, a proteolytic enzyme, is...
At the onset of anaphase, separase, a proteolytic enzyme, is...
02:19The Spindle Assembly Checkpoint
The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
02:02Meiosis II
Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
02:15M-Cdk Drives Transition Into Mitosis
Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...