PgmNr W4057: Development of Quantitative Imaging Toolkit to Monitor the Process of Symmetry Breaking.

Authors:
P. ZHAO 1,2 ; Z. ZHANG 2,3 ; H. T. ONG 2,3 ; T. KANCHANAWONG 2,3 ; F. MOTEGI 1,2,3


Institutes
1) Temasek Life Sciences Laboratory, Singapore; 2) National University of Singapore, Singapore; 3) Mechanobiology Institute, Singapore.


Keyword: Cell polarization

Abstract:

Caenorhabditis elegans early zygote undergoes de novo polarization upon fertilization. Previous studies have shown that maturing centrosomes could break symmetry by destabilizing contractile network of actomyosin, leading to segregate PAR-type polarity regulators along the anterior-posterior axis. Centrosome maturation-defective mutants, however, can break symmetry during the later stage of first mitosis, and occasionally formed two posterior domains. To assess how singularity can be established and/or violated under the compromised centrosomes, we developed quantitative image-analysis tools to monitor subtle changes of cortical actomyosin and PAR proteins in response to centrosome movement with high temporal and spatial resolution. We observed in different mutant embryos that early zygote retains the competency to break symmetry throughout the first cycle, during meiotic to mitotic transition, upon mitotic entry, and even during cytokinesis. The quantitative imaging also observed roles of several mitotic kinases in global control of cortical actomyosin dynamics. We will discuss a progress of our quantitative screening to identify genes essential for cortical symmetry breaking in early zygotes.