PT  - JOURNAL ARTICLE
AU  - Judith Reichmann
AU  - Bianca Nijmeijer
AU  - M. Julius Hossain
AU  - Manuel Eguren
AU  - Isabell Schneider
AU  - Antonio Z. Politi
AU  - M. Julia Roberti
AU  - Lars Hufnagel
AU  - Takashi Hiiragi
AU  - Jan Ellenberg
TI  - Dual spindle formation in zygotes keeps parental genomes apart in early mammalian embryos
AID  - 10.1101/198275
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 198275
4099  - http://biorxiv.org/content/early/2017/12/15/198275.short
4100  - http://biorxiv.org/content/early/2017/12/15/198275.full
AB  - At the beginning of mammalian life the genetic material from each parent is replicated in a separate pronucleus and meets for the first time when the fertilized egg divides. So far, it was thought that a single microtubule spindle is responsible to spatially combine the two genomes and then segregate them to create the two-cell embryo. Utilising the high spatio-temporal resolution of light-sheet microscopy, we show that two separate bipolar spindles form in the zygote, that independently congress and segregate the maternal and paternal genomes. These two spindles normally align their poles prior to anaphase but keep the parental genomes apart during the first embryonic division. This spindle assembly mechanism provides a rationale for the high frequency of erroneous divisions into more than two blastomeric nuclei observed in mammalian zygotes and reveals the mechanism behind the long-standing observation that parental genomes occupy separate nuclear compartments in the two-cell embryo.One Sentence Summary After fertilization, two spindles form around pro-nuclei in mammalian zyogotes and keep the parental genomes apart during the first division.