A single E-box in the Cel-lin-3 CRM is not sufficient for lin-3 expression in the anchor cell of C. elegans.
(A) New cis-regulatory lin-3 alleles with deleted E-boxL and NHR or NHR and E-boxR. (B) Quantification of vulval induction in these new mutants. Note the complete absence of any induction in the recovered lin-3 alleles (n>30). Scorings of lin-3(1417) animals are the same as those reported in Fig 5 and are used here to indicate that this mutation leads to vulval hypo-induction rather than no induction at all. (C-D) smFISH in lin-3(mf72) (C) and N2 (D) animals. Green spots correspond to lin-3 transcripts and red spots to lag-2 that is used as an anchor cell marker. Blue is DAPI staining of nuclei. Note the absence of lin-3 expression in the anchor cell in the lin-3(mf72) mutant animal. Absence of lin-3 signal in the anchor cell was also confirmed for the other lin-3 alleles.