title: Automated mitotic spindle tracking suggests a link between spindle dynamics, spindle orientation, and anaphase onset in epithelial cells.
abstract: Proper spindle positioning at anaphase onset is essential for normal tissue organization and function. Here we develop automated spindle-tracking software and apply it to characterize mitotic spindle dynamics in theXenopus laevisembryonic epithelium. We find that metaphase spindles first undergo a sustained rotation that brings them on-axis with their final orientation. This sustained rotation is followed by a set of striking stereotyped rotational oscillations that bring the spindle into near contact with the cortex and then move it rapidly away from the cortex. These oscillations begin to subside soon before anaphase onset. Metrics extracted from the automatically tracked spindles indicate that final spindle position is determined largely by cell morphology and that spindles consistently center themselves in theXY-plane before anaphase onset. Finally, analysis of the relationship between spindle oscillations and spindle position relative to the cortex reveals an association between cortical contact and anaphase onset. We conclude that metaphase spindles in epithelia engage in a stereotyped "dance," that this dance culminates in proper spindle positioning and orientation, and that completion of the dance is linked to anaphase onset.
authors.affiliation: Medical Scientist Training Program, University of Wisconsin-Madison, Madison, WI 53706 melarson3@wisc.edu wmbement@wisc.edu.|Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, Madison, WI 53706.|Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Larson
authors.affiliation: Medical Scientist Training Program, University of Wisconsin-Madison, Madison, WI 53706 melarson3@wisc.edu wmbement@wisc.edu.|Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, Madison, WI 53706.|Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706.|Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: William M
authors.initials: WM
authors.lastname: Bement
mesh_terms: D000705:Anaphase / Q000502:physiology; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D004848:Epithelium / Q000378:metabolism; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008870:Microtubules; D008938:Mitosis / Q000502:physiology; D012984:Software; D062211:Spatio-Temporal Analysis; D008941:Spindle Apparatus / Q000378:metabolism* / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism