9616138 Burggren Our understanding of the forming cardiovascular system of early embryos remains extraordinarily limited for any vertebrate, including mammals. Simply put, the vertebrate embryo remains a "black box" from an "organismal physiology" perspective. Consequently, the major objectives of this proposal are to: 1) investigate the onset of cardiovascular function by determining experimentally the physiological mechanisms leading to flow and pressure generation in early stages of heart development; 2) clearly define and delineate the "critical windows" for cardiovascular development; 3) determine whether "development trajectories" - established early in embryonic development and dictated by genotype - can be diverted through challenge by environmental factors to produce altered embryonic/larval phenotype. Measurements will be made zebrafish, the African clawed frog, and the domestic fowl. The first phase of experiments will include measurements during the early embryonic period of in vivo physiological variables. The second experimental phase will consist of rearing populations of developing embryos under low oxygen and assessing their physiological performance and anatomical development. These studies on early embryonic cardiovascular development and how relevant environmental factors (e.g. hypoxia) impact it will have very broad applicability to both vertebrate physiology and developmental biology, particularly in the almost complete absence of similar published data for vertebrate embryos.
