Meeting Abstract
143.4 Monday, Jan. 7 Ontogeny of Cardiovascular Physiology In Embryonic Reptiles: Capacity for and susceptible periods of Environmentally-induced Phenotypic Plasticity. EME, J.; Univ. of North Texas dane.crossley@unt.edu
In response to chronic developmental stress, embryonic reptiles exhibit phenotypic plasticity resulting in multiple morphological and physiological modifications. Utilizing the developmental stressor, chronic hypoxic, we have investigated the plasticity of cardiovascular regulatory maturation in two species, the American alligator and the common snapping turtle. These species exhibit both common and unique responses to developmental challenges. Both species exhibit phenotypic plasticity in relative heart mass and intrinsic heart rate, with a common increase in heart mass and depression in heart rate in response to hypoxic stress. However, they differ in their capacity to modify the timing of cardio-regulatory ability and the strength of each regulatory mechanism during development. These include the activation of vagal tone on the heart and a cardiovascular chemoreflex. To investigate the developmental periods during which the cardiovascular system is amenable to environmentally induced phenotypic change, we focused on the American alligator. Relocation of hypoxic (10% O2) incubated embryos to normoxia (H to N) at 70% of incubation returned heart mass to control values measured at 90% of development. The opposite manipulation (N to H) did not result in an increase in relative heart mass compared with hypoxic-incubated (control) animals measured at 90%. Physiological phenotype was also altered by this manipulation resulting in an intrinsic heart rate that was reduced by the N to H shift compared to the H to N change. Collectively these data indicate that the degree cardiovascular developmental phenotypic plasticity is species dependent and may require exposure during finite windows of development to produce a given response. NSF CAREER IBN IOS-0845741 to DAC
