Fig. 7. Expression of vab-7 in embryos overexpressing tbx-8 or tbx-9. Expression of vab-7::GFP was monitored in worms that also carried integrated hsp16-2::tbx-8 + hsp16-41::tbx-8 or hsp16-2::tbx-9 + hsp16-41::tbx-9 constructs in which high level expression of tbx-8 or tbx-9 could be ubiquitously induced by heat treatment. (A-B) Following heat-shock induction of tbx-8 at 33°C for 45 minutes and a subsequent incubation at 20°C for 2 hours, ectopic vab-7::GFP expression can be seen up to the 400-cell stage. (A) Early embryos; (B) later embryos around the 400-cell stage. (C-D) Similar results were obtained following heat shock induction of tbx-9, using the same heat treatment conditions. (E-F) vab-7::GFP embryos that do not contain the hsp16::tbx-8 or hsp16::tbx-9 constructs, subject to the same heat treatment regime. VAB-7 is seen in very few posterior cells around the 200-cell stage (E), and in muscle cells around the 400-cell stage, as has been previously reported (Ahringer, 1996) (this report). Posterior is to the right in all panels. Scale bar, 10 µm.