AYERS, M*; MOORE, F; BAGATTO, B; University of Akron; University of Akron; University of Akron: Searching for Critical Windows in the Develoipment of the Zebrafish Cardiovascular System
Fluctuations in aquatic oxygen concentrations are often experienced by developing fish and can have significant implications on the adult phenotype. It has been suggested that there are certain times during development that may be more sensitive to environmental hypoxia. To address the possibility, zebrafish (Danio rerio) eggs were reared in both hypoxic (<2.0 mgO2/L) and normoxic (>6.0 mgO2/L) environments. Fifty eggs were randomly selected from each group and cross-transplanted (hypoxia-reared eggs moved to normoxia environment and vice versa) at 4, 6, 8, and 12 hours post-fertilization. Developmental stages were then monitored until 72 hours post-fertilization and video recordings were taken to determine heart rate, RBC count, and stroke volume. It was predicted that hypoxia-reared embryos would develop slower morphologically and the cardiovascular system would develop comparatively sooner. Eggs cross-transplanted earlier during development were predicted to recover and follow the new environment developmental trajectory, while those transplanted at 8 and 12 hours were predicted to not recover developmentally. Preliminary results show that hypoxia and normoxia-reared embryos maintained a very similar developmental rate at 25C. Eggs reared exclusively in hypoxia showed increased membrane damage along with heartbeat and vessel formation 3-6 hours prior to normoxia-reared embryos. Eggs cross-transplanted at 4, 6, 8, and 12 hours of development did not differ significantly from the controls, since the controls themselves did not show a significant variation. These results are attributed to a low developmental temperature of 25C instead of the optimal 28C. However, when all normoxia-reared were placed in a hypoxic situation, heartbeat and vessel formation were accelerated to that of the hypoxia-reared group. Further experiments are being performed at 28C.
