Fig. 4. Transgenic mRNAs with mutated NREs escape Pumilio regulation. (A) The bcd NRE (A and B boxes shaded) and NRE transgenic mutant constructs (NRE1, NRE2; dinucleotide mutations noted). (B) Northern blot of timed samples from wild-type transgenic (wt*, lanes 1-8), NRE1 (lanes 1'-8') and NRE2 (lanes 1''-8'') embryos probed for bcd and rpA1. Both NRE1 and NRE2 transgenics contain bcd at later developmental times. m, size markers. (C) Western blot of wild-type transgenic (wt*, lanes 5-10), NRE1 (5'-10') and NRE2 (5''-10'') mutant embryo extracts probed for Bicoid. The developmental period overlaps with and extends beyond Fig. 4B. The lowest band (secondary antibody crossreaction) acts as a loading control. Transgenics contain a full complement of both endogenous and transgenic bcd mRNAs and Bicoid protein. The wild-type* and NRE1 embryos are homozygotes; the NRE2 mutant line is heterozygote for the bcd transgene.
