Ethanol exposure reduced Bmp activity during heart tube morphogenesis, and later during valvulogenesis, those embryos lost regionalization of Bmp activity at the AVC.

<p>(A-B”) <i>Tg(bre</i>:<i>EGFP)</i> embryos showed reduced GFP label in the cardiac primordia in ethanol exposed embryos (A’-B”) relative to control (A, B) at 16 somite (16s; 17 hpf; A-A”) and heart cone stage (20 hpf; B-B”). Arrowheads: cardiomyocytes; dotted line demarcates the heart cone. (C-D”) Reduced GFP signaling was observed in the linear heart tube (LHT) of ethanol exposed embryos at 24 (C’, C”) and 30 hpf (D’, D”) compared to control (C, D). (E-I”) Examination of Bmp activity from 38–74 hpf showed progressively restricted Bmp activity in the chamber cardiomyocytes and strong activity at the AVC in control embryos (E-I); ethanol treated embryos showed lack of restriction of Bmp activity at the AVC (E’-I”) and occasional weak BMP activity in the heart (H”). Dotted line demarcates the heart. A: Atrium, V: Ventricle.