Cortical flows are indispensable for C. elegans development. Anterioposterior (A/P)1, dorsoventral (D/V)2 and left-right3 asymmetries rely on differential regulation of cortical actomyosin. Our work has shown how a previously un-described rotational cortical flow polarized orthogonal to the A/P axis repositions the cytokinesis midbody remnant (MBr) onto the future ventral side of an otherwise D/V symmetric embryo. The MBr acts as a polarizing cue by serving as a cortical landmark for F-actin accumulation. Upon subjecting the embryos to a transient heat shock we found that the cortical flows are severely diminished4. Acute heat shock abolishes cortical flows leading to loss of all other discernable signs of A/P and D/V polarity. Hallmarks of cell polarity in C. elegans include mutually exclusive polarity domains and asymmetric cell division; both these processes fail in heat stressed embryos. We observed mass internalization of cortical domains loaded with polarity markers (PAR-2/6), indicating that lack of cortical domain recycling leads to polarity loss. Taken together, our work reveals heat-labile aspects of actomyosin regulation, asymmetric cell division and polarity.
Reference list
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4) Singh D et al. Genesis. DOI:10.1002/dvg.22930 (2016).