Quantitative Analysis of Cytokinesis In Situ during C. elegans Postembryonic Development

Abstract

The physical separation of a cell into two daughter cells during cytokinesis requires cell-intrinsic shape changes driven by a contractile ring. However, in vivo, cells interact with their environment, which includes other cells. How cytokinesis occurs in tissues is not well understood. Here, we studied cytokinesis in an intact animal during tissue biogenesis. We used high-resolution microscopy and quantitative analysis to study the three rounds of division of the C. elegans vulval precursor cells (VPCs). The VPCs are cut in half longitudinally with each division. Contractile ring breadth, but not the speed of ring closure, scales with cell length. Furrowing speed instead scales with division plane dimensions, and scaling is consistent between the VPCs and C. elegans blastomeres. We compared our VPC cytokinesis kinetics data with measurements from the C. elegans zygote and HeLa and Drosophila S2 cells. Both the speed dynamics and asymmetry of ring closure are qualitatively conserved among cell types. Unlike in the C. elegans zygote but similar to other epithelial cells, Anillin is required for proper ring closure speed but not asymmetry in the VPCs. We present evidence that tissue organization impacts the dynamics of cytokinesis by comparing our results on the VPCs with the cells of the somatic gonad. In sum, this work establishes somatic lineages in post-embryonic C. elegans development as cell biological models for the study of cytokinesis in situ.

Anillin Regulates Neuronal Migration and Neurite Growth by Linking RhoG to the Actin Cytoskeleton

“…Heat-shock treatment did not cause defects in embryonic viability or inhibit larval development in wild-type (WT) animals; however, the conditional ani-1 mutant embryos exhibited embryonic lethality with penetrances of 55% (ani-1-sg1) and 35% (ani-1-sg2) and larval arrest phenotypes in 18% of ani-1-sg1 and 35% of ani-1-sg2 animals ( Figure 1G), which are consistent with the phenotypes of ani-1 RNAi animals. C. elegans ANI-1 was previously reported to be dispensable for cytokinesis in early embryos, whereas recent studies showed that ANI-1 is essential for cytokinesis in embryonic neuroblasts and vulval precursor cells [16,17,21,27]. We first determined whether ANI-1 regulates Q neuroblast division.…”

Crosslinkers both drive and brake cytoskeletal remodeling and furrowing in cytokinesis

“…To compare simulation results with in vivo data, we acquired optical sections throughout the thickness of C. elegans zygotes, rotated image data sets 90 degrees to observe the 7 entire division plane, visualized with a fluorescently-tagged ring component, and used custom Matlab-based software to annotate the position of the cytokinetic ring over time ( Figure 1D, E; (Dorn et al, 2010)). As in silico, the ring closed in an average of 5 minutes, accelerating until approximately half closed, and then decelerating ( Figure 1F, F'; (Bourdages et al, 2014)). Thus, simulated control rings and rings visualized in vivo exhibited similar closure dynamics, suggesting that our in silico approach using bipolar motor ensembles faithfully recapitulates some aspects of in vivo ring dynamics.…”

“…Anaphase onset was determined by observing a separation between chromatin masses visible against the background of myosin fluorescence in the spindle. Ring closure was determined using semi-automated custom software cyanRing (for CYtokinesis ANalysis of the RING) as described previously (Dorn et al, 2010;Bourdages et al, 2014). In cyanRing, the equatorial region of the embryo is cropped from the 3D image stack, rotated, and maximum-intensity projected to produce a view of the cytokinetic ring along the spindle axis as viewed from the posterior direction.…”

Mitotic Cell Division in Caenorhabditis elegans

“…During each of the first three divisions of the C. elegans embryo, there is a substantial period following the onset of ring constriction when the overall rate of ring closure remains approximately constant despite the fact that the ring is progressively decreasing in size (Zumdieck et al 2007;Carvalho et al 2009;Bourdages et al 2014). Thus the per-unit-length rate of closure increases as the circumference decreases.…”