Choice between 1- and 2-furrow cytokinesis inCaenorhabditis elegansembryos with tripolar spindles

Abstract

Excess numbers of centrosomes often lead to multipolar spindles, and thus probably to multipolar mitosis and aneuploidy. In Caenorhabditis elegans, approximately 70% of the paternal emb-27 APC6 mutant embryonic cells contained more than 2 centrosomes and formed multipolar spindles. However, only 30% of the cells with tripolar spindles formed 2 cytokinetic furrows. The rest formed 1 furrow, like normal cells. To investigate the mechanism how the cells avoided to form 2 cytokinetic furrows even with a tripolar spindle, we conducted live-cell imaging in emb-27 APC6 mutant cells. We found that the chromatids were aligned only on 2 of the 3 sides of the tripolar spindle, and the angle of the tripolar spindle relative to the long axis of the cell correlated with the number of cytokinetic furrow. Our numerical modeling showed that the combination of cell shape, cortical pulling forces, and heterogeneity of centrosome size determines whether cells with tripolar spindle form 1 or 2 cytokinetic furrows. anaphase (mat) transition-defective mutants in Caenorhabditis elegans. J. Cell Biol. 151:1469-1482. Gönczy, P. 2008. Mechanisms of asymmetric cell division: flies and worms pave the way. Nat. Rev. Mol. Cell Biol. 9:355-366. . 2001. Polarity controls forces governing asymmetric spindle positioning in the Caenorhabditis elegans embryo. Nature. 409:630-633. doi:10.1038/35054572. Hamaguchi, M.S., and Y. Hiramoto. 1986. Analysis of the role of astral rays in pronuclear migration in sand dollar eggs by the colcemid-UV method. Dev Growth Differ. 28:143-156.

Cytoplasmic streaming drifts the polarity cue and enables posteriorization of theCaenorhabditis eleganszygote at the side opposite of sperm entry

“…RNAi was performed by injecting double-stranded RNAs, as described previously ( Kimura and Kimura, 2012 ). For the mating experiments, CAL0182 (carrying fem-1(hc17) ) hermaphrodites ( Kondo and Kimura, 2019 ) were grown at restrictive temperature (25°C) and were mated to CAL0841 (carrying him-5(e1490) ) males. CAL1041 hermaphrodites were mated to CAL1651 (carrying him-5(e1490) ) males at 22°C.…”

From DNA damage to epithelial integrity: new roles for cell forces

“…Mirror symmetric division with one cytokinetic furrow is the typical outcome of two centrosomes that set up a suitable force balance. Tomo Kondo and coworkers study a C. elegans mutant that mostly exhibits three or more centrosomes per cell, which potentially sets up a complex, multipole tug-of-war. They observe nonetheless that mirror symmetric–type division predominates in experiment, with calculations indicating that this results from polarized cell shapes and cortex-derived tensions.…”