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. Author manuscript; available in PMC: 2014 Nov 15.
Published in final edited form as: Dev Biol. 2013 Sep 25;383(2):214–226. doi: 10.1016/j.ydbio.2013.09.019

Figure 5. Endocardial intercellular junctions are disorganized following heart tube extension in tal1-deficient embryos.

Figure 5

(A–D) Immunofluorescence detects localization of ZO-1 (red) in wild-type (A, C) and tal1-deficient (B, D) hearts at 25 hpf; lateral views, ventricular end of the heart tube at the top. An anti-GFP antibody allows visualization of Tg(kdrl:GRCFP) expression (green) in the endocardium.

(A, B) Three-dimensional reconstructions of confocal stacks demonstrate that ZO-1 is located around the perimeter of the myocardial cells in both wild-type and tal1-deficient hearts. (C) Optical slice of a wild-type heart reveals that ZO-1 is localized in discrete puncta at points of endocardial cell-cell contact; in addition, wild-type endocardial cells exhibit a flattened and elongated morphology. (D) Optical slice of a tal1-deficient heart reveals that ZO-1 is mislocalized in large clusters around the perimeter of the endocardial cells; in addition, the tal1-deficient endocardial cells exhibit a rounded shape, rather than the normal elongated shape.

(E, F) Immunofluorescence detects ZO-1 (purple) in wild-type (E) and tal1-deficient (F) hearts at 25 hpf; lateral views, ventricular end of the heart tube at the top. Expression of the Tg(fli1a:negfp) (green) and Tg(myl7:H2A-mCherry) (red) transgenes reveals one endocardial cell with ectopic myocardial gene expression (arrow). Subcellular localization of ZO-1 is aberrant in the majority of tal1-deficient endocardial cells, nearly all of which do not display ectopic myocardial gene expression.