Endogenous PLST-1 labeled with GFP localizes to the cortex of newly fertilized C. elegans zygotes. (A) Cortical view of the newly fertilized C. elegans zygote coexpressing PLST-1::GFP and the F-actin reporter Lifeact::RFP. Punctate and filamentous structures are highlighted by yellow and red arrowheads, respectively. Colocalization of the PLST-1::GFP and Lifeact::RFP signals is shown in the merged channel and representative band scans. (B) Pearson’s correlation between PLST-1::GFP and Lifeact::RFP at various stages in single-cell zygote (n ≥ 8). (C) Filamentous and punctate structures formed by PLST-1::GFP can be separated by arx-2 and cyk-1 RNAi. (D) Ratiometric analysis of PLST-1::GFP/Lifeact::RFP fluorescent intensities reveals that PLST-1::GFP signal is enriched in contractile structures. (E) Time lapse of PLST-1::GFP/Lifeact::RFP during the formation and the subsequent disassembly of a contractile F-actin cluster during polarity establishment. Data are represented as mean ± SEM. Bars, 5 µm.