Figure 1.
(A) Representative images of embryos analyzed in B and D. In situ hybridization with a sox17 probe at 75% epiboly; dorsal to the right. Endoderm in toddler;lefty2 double mutants resembles toddler single mutants. (B) The number of lateral endodermal cells is increased in toddler;lefty2 double mutants compared to wild-type and toddler single mutant embryos. Each point represents a single embryo. Red bars are averages. p-Values for pairwise comparison with wild type unless otherwise noted. **p<0.001; unpaired two-tailed t-test. N = number of independent experiments; n = number of embryos. (C) Schematic representation of experimental measurements shown in B and D. The locations of lateral endodermal cells in individual embryos are measured relative to the AP-VP axis and then consolidated across embryos. (D) Measurement of frequency with which cells were found at a given location in an embryo of a certain genotype. A cell at the animal pole corresponds to 100% embryo height, while a cell at the vegetal pole corresponds to 0%. AP = Animal pole; VP = vegetal pole. The same embryos were measured in B and D.
Figure 1—figure supplement 1.
(A–C) n = number of embryos (A) Number of lateral endodermal cells in wild-type and toddler mutant embryos during gastrulation. (B) Rate of endodermal cell division in wild-type and toddler mutant embryos. 40–60 cells were tracked per embryo and the percentage of those cells that divided is shown. Red bars are averages. (C) Percentage of embryos with a given number of TUNEL +cells on one side of the embryo. (D) Representative images of TUNEL staining at two time points in toddler mutants. (E) Live tracking of endoderm using sox17:GFP transgenic fish captures two endodermal cells undergoing cell death during gastrulation in toddler mutants (arrows). A cell that is about to divide is also present (asterisk).
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