RT Journal Article SR Electronic T1 Astral microtubule crosslinking by Feo safeguards uniform nuclear distribution in the Drosophila syncytium JF bioRxiv FD Cold Spring Harbor Laboratory SP 859975 DO 10.1101/859975 A1 Ojas Deshpande A1 Jorge de-Carvalho A1 Diana V. Vieira A1 Ivo A. Telley YR 2020 UL http://biorxiv.org/content/early/2020/07/17/859975.abstract AB The early insect embryo develops as a multinucleated cell distributing genome uniformly to the cell cortex. Mechanistic insight for nuclear positioning beyond cytoskeletal requirements is missing to date. Contemporary hypotheses propose actomyosin driven cytoplasmic movement transporting nuclei, or repulsion of neighbor nuclei driven by microtubule motors. Here, we show that microtubule crosslinking by Feo and Klp3A is essential for nuclear distribution and internuclear distance maintenance. Germline knockdown causes irregular, less dense nuclear delivery to the cell cortex and smaller distribution in ex vivo embryo explants. A minimal internuclear distance is maintained in explants from control embryos but not from Feo-depleted embryos, following micromanipulation assisted repositioning. A dimerization deficient Feo abolishes nuclear separation in embryo explants while the full-length protein rescues the genetic knockdown. We conclude that Feo and Klp3A crosslinking of antiparallel microtubule overlap generates a length-regulated mechanical link between neighboring microtubule asters. Enabled by a novel experimental approach, our study illuminates an essential process of embryonic multicellularity.Competing Interest StatementThe authors have declared no competing interest.