TABLE 1:
Comparison of Rappaport furrow formation in metazoan systems.
| System | Mammalian tissue culture | C. elegans egg | Echinoderm egg | Xenopus egg |
|---|---|---|---|---|
| Cell diameter (μm) | ∼15 | ∼30 | ∼100 | ∼1200 |
| Rappaport furrows?a | Yes | Yes | Yes | Nob |
| Microtubule organization in asters | Single microtubules grow from centrosome to cortex | Single microtubules grow from centrosome to cortex | Not known | Most microtubules are nucleated away from centrosome |
| Equatorial microtubule morphology in cytokinesis | Midzone bundles and aster plus ends at cortex | Midzone bundles and aster plus ends at cortex | Midzone bundles and aster plus ends at cortex | Uniform disk of antiparallel bundles |
| CPC localization in normal furrows | Midzone, cortex, midbody | Midzone, midbody | Midzone, midbody | Uniform disk |
| CPC localization in Rappaport furrows | Midbodyc | Not tested | Not localized (but required)d | No Rappaport furrows |
| Centralspindlin localization in normal furrows | Midzone, cortex, midbody | Midzone, cortex, midbody | Midzone, cortex, midbody | Uniform disk |
| Centralspindlin localization in Rappaport furrows | Midbodyc | Not tested | Midzone, cortex, midbody | Not tested |
References: mammalian, Reider et al. (1997) and Savoian et al. (1999); C. elegans, Baruni et al. (2008), Lewellyn et al. (2011), and Basant et al. (2015); echinoderm, Rappaport (1961, 2005) and Argiros et al. (2012); Xenopus, Render and Elinson (1986), Ishihara et al. (2014), Nguyen, Groen et al. (2014), and this study.
aWe define a “Rappaport furrow” as a furrow induced between two asters that did not emanate from the poles of the same mitotic spindle, termed “nonsister asters” in this article.
bRappaport furrows were not observed after fertilization with two to four sperm per egg. CPC localization between nonsister asters, presumably followed by Rappaport furrows, could be observed after highly polyspermic fertilization (Figure 2).
cLocalization of CPC and Centralspindlin in Rappaport furrows in tissue culture cells was only assessed late in cytokinesis in midbodies.
dAurkB activity was required for ingression of Rappaport furrows in echinoderm zygotes even though the CPC was not localized between nonsister asters.