Time-lapse fluorescence microscopy of embryos was performed to trace the level of GFP expression during early stages, and showed progressively higher GFP signals. Dynamic up-regulation of GFP levels was more prominent in the
ncl-1(
e1942); cguIs1 embryos (62.8%) than in cguIs1 (26.9%). Random collections of embryos from both transgenic worms were further examined to quantify the GFP intensity of each embryo in the same field and subsequently revealed that the embryos in the absence of NCL-1 exhibited higher levels of FIB-1::GFP (about 2 fold). Further expression analyses consistently showed elevated levels of FIB- 1 in
ncl-1(
e1942) embryos (5.2 fold) and adult worms (1.7 fold). Unexpectedly, RT- qPCR analysis revealed comparable levels of
fib-1 mRNA in wild type and
ncl-1(
e1942) in embryo and adult stages. Taken together, these findings indicate that
ncl-1 is an upstream negative regulator of
fib-1 expression at the post-transcriptional/translational stage.