Fig. 3. Endodermally expressed HFGa13 causes abnormal hindgut and tail development. (A) Whole-mount in situ hybridization showing RCAS expression (arrow at malformed tail) in an E6 mutant HFGa13-infected embryo. (B) 3C2 immunohistochemistry analysis of sectioned HFGa13-infected mutant embryo shows posterior endoderm (endo.) and mesoderm (meso.) infection. (C) RCAS in situ showing absence of the mutant phenotype (arrow at normal tail) when HFGa13 infection is present only in the mesoderm, demonstrated in D using anti-Gag immunohistochemistry to show no infection in the caudal endoderm (at E6). (E) E6 survivors after electroporation of HFGa13 constructs in the posterior endodermal layer. The phenotype involves maldevelopment of the cloaca (CL*), hindgut (HG*) and tail. Allantoic internalization is present (AL*) and ceca are unaffected (CE). (F) Anti-N-flag immunostaining demonstrating expression of the tagged-HFGa13 in the endoderm of the hindgut; the mesoderm is not stained. Note that the electroporated endodermal cells appear undamaged and intact. Misexpression of HFGa13 and Hoxa13 constructs by electroporation show similar expression levels in the gut endoderm layer (data not shown).
