We thank M. van der Zee for the transgenic LifeAct-eGFP Tribolium line; Y. Hsieh for mRNA, P. Mejstrik, T. Pietzsch, M. Burkon and the MPI-CBG Electron and Light microscopy facilities for technical assistance; M. Benton, K. Panfilio, L. Jawerth and P. Gross for helpful discussions; the Tribolium research community for support; and C. Norden, E. Knust and C. Zechner for comments on the manuscript. A.J. received a DIGS-BB fellowship, and S.M. was supported by an ELBE post-doctoral fellowship. S.W.G. acknowledges support from the European Research Council (CHIMO, grant No 742712) and the Deutsche Forschungsgemeinschaft (DFG) under Germany´s Excellence Strategy – EXC-2068 – 390729961.

Reviewer information

Nature thanks Kristen Panfilio, Siegfried Roth and the other anonymous reviewer(s) for their contribution to the peer review of this work.