Forer, ArthurBerns, MichaelShah, JageshLiaw, Lih-HueiGomez, VeronicaBaker, NormanSheykhani, Rozhan2021-02-222021-02-222013-05Cytoskeleton (Hoboken). 2013 May;70(5):241-59.1949-3584https://doi.org/10.1002/cm.21104http://hdl.handle.net/10315/38108This study investigates spindle biomechanical properties to better understand how spindles function. In this report, laser microbeam cutting across mitotic spindles resulted in movement of spindle poles toward the spindle equator. The pole on the cut side moved first, the other pole moved later, resulting in a shorter but symmetric spindle. Intervening spindle microtubules bent and buckled during the equatorial movement of the poles. Because of this and because there were no detectable microtubules within the ablation zone, other cytoskeletal elements would seem to be involved in the equatorial movement of the poles. One possibility is actin and myosin since pharmacological poisoning of the actin-myosin system altered the equatorial movements of both irradiated and un-irradiated poles. Immunofluorescence microscopy confirmed that actin, myosin and mono-phosphorylated myosin are associated with spindle fibres and showed that some actin and mono-phosphorylated myosin remained in the irradiated regions. Overall, our experiments suggest that actin, myosin and microtubules interact to control spindle length. We suggest that actin and myosin, possibly in conjunction with the spindle matrix, cause the irradiated pole to move toward the equator and that cross-talk between the two half spindles causes the un-irradiated pole to move toward the equator until a balanced length is obtained.enWiley This is the peer reviewed version of the following article: [Cytoskeleton (Hoboken). 2013 May;70(5):241-59.], which has been published in final form at [https://doi.org/10.1002/cm.21104]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Attribution-NoDerivatives 4.0 Internationalspindle organizationactomyosinmono-phosphorylated myosinmicrotubule ablationspindle matrixArticlehttps://www.ncbi.nlm.nih.gov/https://onlinelibrary.wiley.com/https://pubmed.ncbi.nlm.nih.gov/23475753/