Fig. 6

MZezh2 mutant embryos display impaired myocardial and gastrointestinal tissue maintenance.

(a) In situ hybridization for myl7 at different time points in MZezh2^hu5670/+ and MZezh2^{hu5670/hu5670}. At 1 dpf the heart of MZezh2^{hu5670/hu5670} is straight. In MZezh2^{hu5670/hu5670} embryos myl7 expressing cells are found outside the heart at 1.5 dpf (arrow heads). At 2 dpf the number of myl7 expressing cells is decreased in MZezh2^{hu5670/hu5670} compared to MZezh2^hu5670/+. (b) Stills of time lapse (Supplementary Movie S1, 2) imaging of Tg(myl7::GFP) MZezh2^hu5670/+ and MZezh2^{hu5670/hu5670} embryos from 1 to 2 dpf. In MZezh2^{hu5670/hu5670} embryos, GFP-positive cells are moving away from the heart (arrows). Arrow heads point at ventricle and atrium. (c) Immunostaining for GFP to visualize Tg(myl7::GFP) (brown precipitation, arrow heads) combined with in situ hybridization for nkx2.5 (purple staining, arrows) at 2 dpf. In MZezh2^hu5670/+ no nkx2.5 expressing cells are present. In MZezh2^{hu5670/hu5670} cells that are detached from the heart express nkx2.5. The right panel shows a zoom-in of the left panel (white square). Scale bar is 50 µm. (d) Immunostaining for GFP Tg(myl7::GFP) combined with in situ hybridization for nppa at 2 dpf in MZezh2^hu5670/+ and MZezh2^{hu5670/hu5670} embryos. Two embryos per genotype are shown. In MZezh2^{hu5670/hu5670} embryos nppa expression is absent in one and not ubiquitous in the other embryo (arrow heads). In MZezh2^hu5670/+ nppa is expressed in atrium and ventricle (arrow heads). Scale bar is 50 µm. (e) In situ hybridization for different gastrointestinal tract markers at 1 and 2 dpf in MZezh2^{hu5670/hu5670} and MZezh2^hu5670/+. Expression of gata6 is present in both MZezh2^{hu5670/hu5670} and MZezh2^hu5670/+ at 1 and 2 dpf. At 2 dpf the intestinal tube appears straight in the MZezh2^{hu5670/hu5670}, whereas structures like the liver and pancreas can be seen in MZezh2^hu5670/+ (arrow heads). MZezh2^{hu5670/hu5670} are able to form a gastrointestinal tract, observed by in situ hybridization for foxa3 at 2 dpf, although the organs are bilaterally formed (arrow heads). In MZezh2^{hu5670/hu5670} no expression of terminal differentiation markers for liver, fabp10, and exocrine pancreas, try, was observed. Scale bar is 100 µm. Numbers indicate the number of embryos with the displayed phenotype compared to the total number of embryos analyzed.