Meeting Abstract
10.3 Monday, Jan. 4 Mechanisms of hypoxia effects on body size of Drosophila melanogaster HEINRICH, E.C.*; KLOK, C.J.; HARRISON, J.F.; FARZIN, M.; MCKINLEY, B.; Arizona State University; Arizona State University; Arizona State University; Arizona State University erica.heinrich@asu.edu
Low atmospheric oxygen concentrations decrease the size of many animals including the vinegar fly, Drosophila melanogaster, but the mechanisms of this effect remain unclear. We tested for a critical period when hypoxia effects body size by rearing flies in 10% oxygen only during the egg, larval, or pupal stage, and by rearing flies continuously in either 10 or 21% oxygen except for 24 h periods when the oxygen level was switched. These studies revealed that hypoxia exposure during any developmental stage causes smaller adults, and in most cases, hypoxia at different stages or durations led to similar size reductions. We compared wing size, wing cell size and wing cell number in flies exposed to hypoxia during different developmental stages. Exposure to hypoxia during the egg phase reduced the number of cells, while exposure to hypoxia during the pupal phase reduced the size of cells. We tested for potentially critical role-specific sensing pathways in epithelial cells during the hypoxic response using RNAi to reduce epithelial gene expression of eight genes in putative hypoxia-sensing pathways. Reduction of expression of these eight genes had no effect on the hypoxic-reduction of body size, suggesting that the targeted pathways may be redundant or not in the epithelial cells. The only significant effect of RNAi treatments on size was that knockdown of tango (homolog to mammalian HIF-beta) caused flies reared in 21% to be significantly larger, suggesting that the HIF pathway expression in epithelial cells may reduce body size of normoxic flies. In summary, our data suggest that developmental plasticity causes flies to develop into a target size associated with that oxygen level via multiple redundant mechanisms. Supported by NSF IBN 0419704 and NSF EAR 0746352 to JFH.
