Congenital heart defects are often accompanied by improper blood flow throughout the heart, leading to greater complications in patients born with such defects and often resulting in higher mortality rates. Given the severity of these conditions, it is important to understand more about the development of heart defects and how they specifically impact the cardiovascular system. To accomplish this it is relevant to examine the effects of Retinoic Acid (RA), a known contributor to cardiovascular development signalling. In vertebrates, the heart develops in two major steps. Zebrafish heart development takes place in two temporally distinct steps with the second occuring after 24 hours post-fertilization (hpf). The role of RA during this second phase of development is not fully understood. To examine its effects during the second phase of heart development, we used the RA inhibitor N,N-Diethylaminobenzaldehyde (DEAB) to treat zebrafish embryos. To establish a control group, we treated embryos with Dimethyl Sulfoxide (DMSO). Incubation of embryos began at 24 hpf and ended at 72 hpf. We used confocal imaging to count cells in both the atrium and ventricle. Cell-counting revealed that, at 72 hpf, there were no significant differences found in cells of the atrium. However, there were fewer cells in the ventricle when treated with DEAB compared to the control. In either chamber of the heart we examined varied morphology. These results reveal that endogenous RA plays an important role in the second phase of heart development as well as morphology of the OFT.
Author(s): Kiki Kollar, Biology and Premedical Studies Major
Advisor(s): Jennifer Schumacher, Department of Biology
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