Figure 4. Generation and fate of the PVT neuron are unaffected in
lim-6 ceh-14 double mutants. (A)
srq-1::gfp (otIs85) and
unc-47delta::gfp (otIs39) are markers for PVT cell fate. In addition to PVT,
srq-1 is expressed in one more tail neuron and several head neurons. The
unc-47delta::gfp constructs labels not only the RMEL/R, RIS, AVL and DVB, as described previously (Eastman et al., 1999), but also the PVT neuron. Expression of the two other PVT cell fate markers used here (B),
gpa-2 and
pin-2, has been previously documented (Hobert et al., 1999a; Zwaal et al., 1997) and is not shown. (B) Expression of PVT cell fate markers in mutant backgrounds. All alleles shown are molecular nulls. Scoring was carried out in L1 and L2 stage animals. Sample size was 28-187, depending on genotype. Expression of
unc47delta::gfp (otIs39) in PVT is seen only in 15% of post-L3 stage
lim-6 ceh-14 animals (n=14), while wild type shows expression in more than 95% at pre-L3 stages. This stage-dependent downregulation is difficult to interpret, however, because three out of four integrants of the
unc47delta::gfp reporter line juEx60 show no expression in PVT beyond the L3 stage, while only one integrant, otIs39 (tested here), shows expression after the L3 stage. We also noted that in
lim-6 ceh-14; otIs39 animals, DVB axon morphology often appears defective.