CYE-1::GFP was expressed in the Z1.a/Z4.p cells before their division. Within 2 hrs after their division, the GFP signal decreased in the Z1.aa/Z4.pp but not in the Z1.ap/Z4.pa cells. Therefore, CYE-1 is expressed asymmetrically between the daughters of the Z1.a/Z4.p cells. Similar asymmetric expression was also detected using a
cye-1 promoter::GFP fusion gene (
cye-1p::gfp), which lacks the
cye-1 coding sequence, indicating that the asymmetry is regulated at the transcriptional level.