These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Interconversion of metaphase and interphase microtubule arrays, as studied by the injection of centrosomes and nuclei into Xenopus eggs.
    Author: Karsenti E, Newport J, Hubble R, Kirschner M.
    Journal: J Cell Biol; 1984 May; 98(5):1730-45. PubMed ID: 6725396.
    Abstract:
    We have designed experiments that distinguish centrosomal , nuclear, and cytoplasmic contributions to the assembly of the mitotic spindle. Mammalian centrosomes acting as microtubule-organizing centers were assayed by injection into Xenopus eggs either in a metaphase or an interphase state. Injection of partially purified centrosomes into interphase eggs induced the formation of extensive asters. Although centrosomes injected into unactivated eggs (metaphase) did not form asters, inhibition of centrosomes is not irreversible in metaphase cytoplasm: subsequent activation caused aster formation. When cytoskeletons containing nuclei and centrosomes were injected into the metaphase cytoplasm, they produced spindle-like structures with clearly defined poles. Electron microscopy revealed centrioles with nucleated microtubules. However, injection of nuclei prepared from karyoplasts that were devoid of centrosomes produced anastral microtubule arrays around condensing chromatin. Co-injection of karyoplast nuclei with centrosomes reconstituted the formation of spindle-like structures with well-defined poles. We conclude from these experiments that in mitosis, the centrosome acts as a microtubule-organizing center only in the proximity of the nucleus or chromatin, whereas in interphase it functions independently. The general implications of these results for the interconversion of metaphase and interphase microtubule arrays in all cells are discussed.
    [Abstract] [Full Text] [Related] [New Search]