Fig. 5

Ectopic lefty expression rescues Lefty loss.

(A) lft1^-/-;lft2^-/- mutant donors were injected with 0.4 pg Alexa 488-dextran (3 kD, ThermoFisher) and 10 pg lft1 or lft2 mRNA at the one-cell stage. At sphere stage, around 50 cells from donors were transplanted into the animal pole of lft1^-/-;lft2^-/- mutant host embryos. (B) In host embryos Nodal is inhibited by exogenous, ectopic Lefty. (C,D) Untransplanted wild type (C) and lft1^-/-;lft2^-/- mutant (D) embryos at 1 day post-fertilization (dpf). (E–F’) lft1^-/-;lft2^-/- mutant hosts 30–120 min after receiving cells from donors injected with Alexa 488-dextran + lft1 (E) or lft2 (F) mRNA and at 1 dpf (lft1 mRNA (E’), lft2 mRNA (F’)). Note relatively normal morphology compared to untransplanted lft1^-/-;lft2^-/- sibling (D). Similar results were obtained using donors injected with lft1-gfp (200 pg) or lft2-gfp (60 pg) mRNA (data not shown). Number of embryos with indicated phenotype at 1 dpf/total number embryos receiving lft1-expressing cells: 21/45 normal gross morphology, 11/45 partially rescued (e.g. longer tail but no eyes), 6/45 cyclopia, 2/45 necrotic, and 5/45 dead. Number of embryos with indicated phenotype at 1 dpf/total number embryos receiving lft2-expressing cells: 19/45 normal gross morphology, 16/45 partially rescued, 2/45 cyclopia, 3/45 typical lft1^-/-;lft2^-/- mutant phenotype, 1/45 necrotic, and 4/45 dead.