Metaphase I (MI) (Assembly of meiotic apparatus)
During Metaphase I, Chromosomes move together along the metaphase plate. DNA replication, repair spindle function, and chromosome segregation are controlled by regulatory mechanisms of spindle assembly checkpoints (Elledge, 1996). The cellular spindle apparatus includes the spindle microtubules, associated proteins, and any centrosomes or asters present at the spindle poles. The dynamic lengthening and shortening of spindle microtubules (Mitchison and Kirschner 1984) determines to a large extent the shape of the mitotic spindle and promotes the proper alignment of chromosomes at the spindle midzone. Microtubule-associated proteins (MAPs) associate with microtubules at the midzone and the spindle …show more content…
With its partner, cytoplasmic dynein, NuMA uses its cross-linking properties to tether microtubules to spindle poles. After GVBD, NuMA is aggregated near the chromosomes, and γ-tubulin is also localized to the area surrounding the chromosomes. At MI stage, NuMA is observed in both poles of MI spindle, while γ-tubulin is localized along the spindle microtubules. Then these proteins become re-localized at the spindle midzone during anaphase I and telophase I. These data showed that NuMA and γ-tubulin are involved in microtubule assembly and meiotic spindle poles (Lee et al., 2000; Sun et al., …show more content…
PLK1 also found in MII spindle poles and the spindle fibers of spindle at anaphase-telophase. Its activity is necessary for the function maturation of centrosomes in early prophase and establishment of a bipolar spindle (Stojkovie et al., 1999). PLK1 can also promote kinetochore attachment to microtubules and the spindle checkpoint assembly (Archambault et al., 2009).
In summary of Metaphase I, in this stage, Chromosomes move together along the metaphase plate and spindle apparatus formation. γ-tubulin, NuMA and PLK1 are necessary for meiotic spindle formation. γ-TuRC help to nucleate polymerization of α/β tubulin heterodimers into microtubules, stabilizes microtubule minus-ends and anchors them near the microtubule-organizing center. NuMA is involved in correct spindle assembly during this phase and PLK1 promote kinetochore attachment to microtubules and function of the spindle checkpoint
During Metaphase I, Chromosomes move together along the metaphase plate. DNA replication, repair spindle function, and chromosome segregation are controlled by regulatory mechanisms of spindle assembly checkpoints (Elledge, 1996). The cellular spindle apparatus includes the spindle microtubules, associated proteins, and any centrosomes or asters present at the spindle poles. The dynamic lengthening and shortening of spindle microtubules (Mitchison and Kirschner 1984) determines to a large extent the shape of the mitotic spindle and promotes the proper alignment of chromosomes at the spindle midzone. Microtubule-associated proteins (MAPs) associate with microtubules at the midzone and the spindle …show more content…
With its partner, cytoplasmic dynein, NuMA uses its cross-linking properties to tether microtubules to spindle poles. After GVBD, NuMA is aggregated near the chromosomes, and γ-tubulin is also localized to the area surrounding the chromosomes. At MI stage, NuMA is observed in both poles of MI spindle, while γ-tubulin is localized along the spindle microtubules. Then these proteins become re-localized at the spindle midzone during anaphase I and telophase I. These data showed that NuMA and γ-tubulin are involved in microtubule assembly and meiotic spindle poles (Lee et al., 2000; Sun et al., …show more content…
PLK1 also found in MII spindle poles and the spindle fibers of spindle at anaphase-telophase. Its activity is necessary for the function maturation of centrosomes in early prophase and establishment of a bipolar spindle (Stojkovie et al., 1999). PLK1 can also promote kinetochore attachment to microtubules and the spindle checkpoint assembly (Archambault et al., 2009).
In summary of Metaphase I, in this stage, Chromosomes move together along the metaphase plate and spindle apparatus formation. γ-tubulin, NuMA and PLK1 are necessary for meiotic spindle formation. γ-TuRC help to nucleate polymerization of α/β tubulin heterodimers into microtubules, stabilizes microtubule minus-ends and anchors them near the microtubule-organizing center. NuMA is involved in correct spindle assembly during this phase and PLK1 promote kinetochore attachment to microtubules and function of the spindle checkpoint