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Fig. 2. Constitutively active Drac1 transgene expression causes
contraction of the amnioserosa. Embryos were stained with phalloidin to detect
F-actin (A) or with the anti-phosphotyrosine antibody (B-D). (A) An early
stage 14 GAL4332.3;UAS-Drac1V12 embryo showing dramatic
contraction of amnioserosa into the rear half of dorsal hole. (B) A stage 15
GAL4332.3;UAS-Drac1V12 embryo late in dorsal closure
showing bunched closure of the epidermis around contracted amnioserosa.
Phosphotyrosine staining in the amnioserosa is very intense. (C) An early
stage 14 Hs-GAL4M-4/UAS-Drac1V12 embryo showing an
amnioserosa phenotype similar to that in A. Attachments of the amnioserosa to
the epidermis can be seen (arrowhead). (D) Late stage 14
Hs-GAL4M-4/UAS-Drac1V12 embryo showing bunched closure of
the epidermis around contracted amnioserosa.