Rescue of segmentation by artificial pulses of deltaC expression in dlctw212b/tw212b embryos. Transgenic tg+;dlc embryos (lacking endogenous functional DeltaC) at the 11-12 somite stage were heat-shocked one, two, three or four times, or not at all, left to develop at 28.5°C until 48hpf, and stained as in Fig. 2. Recovery periods between heat-shocks were 25min at 23°C. (A) Scheme of the repetitive heat-shock treatments. (B-G) Typical results for each number of heat-shocks. Orange asterisks mark rescued somite boundaries. Yellow arrowhead in C marks the 17th somite boundary. Note that multiple heat-shocks increase the number of rescued somites: a single heat-shock produced 4.1±0.3 (mean±s.e.m.), two heat-shocks produced 4.7±0.4, three heat-shocks produced 5.0±0.3 and four heat-shocks produced 7.0±0.25. A wild-type (tgdlc+) embryo subjected to a series of four heat-shocks is included as a control; it shows normal segmentation (C). Each photo is representative of n embryos examined, where n=8 for the heat-shocked wild type, and n=20, 21, 22, 22 and 29 for the tg+;dlc embryos subjected to zero, one, two, three and four heat-shocks, respectively.
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