A model for cleavage plane determination in early amphibian and fish embryos.

TitleA model for cleavage plane determination in early amphibian and fish embryos.
Publication TypeJournal Article
Year of Publication2010
AuthorsWühr, M, Tan, ES, Parker, SK, H Detrich, W, Mitchison, TJ
JournalCurr Biol
Date Published2010 Nov 23
KeywordsAnimals, Cell Division, Centrosome, Embryo, Nonmammalian, Embryonic Development, Female, Fertilization, Male, Metaphase, Microtubules, Models, Biological, Spermatozoa, Spindle Apparatus, Xenopus laevis, Zebrafish

<p>Current models for cleavage plane determination propose that metaphase spindles are positioned and oriented by interactions of their astral microtubules with the cellular cortex, followed by cleavage in the plane of the metaphase plate [1, 2]. We show that in early frog and fish embryos, where cells are unusually large, astral microtubules in metaphase are too short to position and orient the spindle. Rather, the preceding interphase aster centers and orients a pair of centrosomes prior to nuclear envelope breakdown, and the spindle assembles between these prepositioned centrosomes. Interphase asters center and orient centrosomes with dynein-mediated pulling forces. These forces act before astral microtubules contact the cortex; thus, dynein must pull from sites in the cytoplasm, not the cell cortex as is usually proposed for smaller cells. Aster shape is determined by interactions of the expanding periphery with the cell cortex or with an interaction zone that forms between sister-asters in telophase. We propose a model to explain cleavage plane geometry in which the length of astral microtubules is limited by interaction with these boundaries, causing length asymmetries. Dynein anchored in the cytoplasm then generates length-dependent pulling forces, which move and orient centrosomes.</p>

Alternate JournalCurr. Biol.
PubMed ID21055946
PubMed Central IDPMC3031131
Grant ListR01 GM039565 / GM / NIGMS NIH HHS / United States
R01 GM039565-23 / GM / NIGMS NIH HHS / United States
R37 GM039565 / GM / NIGMS NIH HHS / United States
GM39565 / GM / NIGMS NIH HHS / United States