Nitric Oxide Signals in Somitogenesis in Chicken Embryos
Authors: Cindy Chu, Tanya Velasco
Faculty Supervisor: Wilfred Denetclaw
Department: Biology
Cells make nitric oxide (NO) by NO synthases and NO is a pleiotropic messenger molecule signaling in embryonic development. Somite segmentation is a repeating process occurring in the cranial end of the segmental plate mesoderm area known as the “determination front.” A physiological regulator in somite segmentation, however, has not been found, although NO may signal in that role. To investigate NO formation, we use the DAF2-DA fluorescent NO indicator with confocal microscopy to monitor NO levels in segmental plate mesoderm and in nascent somites. Our results show for the first time that NO levels are three times more elevated over non-somite areas in the determination front and in the cranial and caudal borders of segmenting somites. Furthermore, the ventral sides of nascent somites show high levels of NO formation in 3–4 newly formed somites but not in maturing somites. We conclude NO regulates in the segmentation of somites into spherical balls that later undergo dorsal-ventral patterning to produce the ventral sclerotome, forming bones and cartilage, and dorsal dermomyotome tissues, giving rise to skeletal muscle and dermis. This research is supported by NSF CCC DBI-1548297 and CIRM COMPASS SFSU-EDUC5-13679.