Abstract:

__Fruitflies, Drosophila melanogaster, and other insects reared in moderate hypoxia are smaller and have increased tracheal diameters and branching. The mechanisms by which hypoxia decreases body size are unclear. It has been demonstrated that very low concentrations of oxygen suppress cell cycle and mitosis in Drosophila embryos and larvae, providing a potential mechanism. In this research we examined the relative contribution of decreases in cell size and cell number to the decrease in body size. One prior study has shown that hypoxia reduces both cell size and number in wing epidermal cells, but it is unclear whether these results can be extrapolated to the entire body. Male fruit flies were reared in 10% and 21% oxygen atmospheres and were collected and sectioned at four days of age. Flies reared in hypoxia had smaller epidermal cells, suggesting that the size at which a cell divides is influenced by cytoplasmic oxygen level, and that this is a major mechanism driving reduced body size. We are also currently analyzing hypoxia effects on cell size in muscle and brain. Supported by NSF IOB-0419704 to JFH.