Somite-Derived Muscle Precursor Cells Migrate into Early-Forming Limb Buds in Response to Molecular Signals in Chicken Embryos
By: Tanya Velasco
Department: Biology
Faculty Advisor: Dr. Wilfred Denetclaw
Nitric Oxide (NO) regulates many physiological events in the human body, such as vascular relaxation, neurotransmission, immune regulation, and cell death. NO autocrine and paracrine signals in somite myogenesis suggesting a role for it in the activation of muscle precursors in both epaxial and hypaxial myotome formation. In the hypaxial domain of somites, muscle precursors migrate into limb buds to give to these forming wings and legs all the skeletal muscles for flight and walking, respectively. We hypothesize that NO signals muscle precursor cells for migration out of the somite and into the adjacent forelimb bud regions. We suggest this is due to NO-induced secretion of hepatocyte growth factor (HGF) in limbs and muscle precursor cells chemoattraction. We are investigating NO for this activity in migration. In our approach, fluorescent vital dyes like DiI and DiO via microinjection are used to fill the somitocoel cavities of somites, so all dermomyotome cells, including muscle precursor cells, are labeled by the dye. After overnight growth, we observe by confocal microscopy muscle precursor cells in migration from somites into the nascent limb buds (wing buds) and a fate map of their migration into dorsal and ventral domains in the limb buds. From the confocal images, we observed the leading and trailing edge of cells, which confirms that they are in active migration. We have been successful in demonstrating morphological changes as cells migrate via DiI microinjection. We will now test NO and regulatory reagents for NO to determine its effects on the migration of muscle precursors into the limbs in embryos. Supported by National Science Foundation (DBI-1548297)