Hypoxia modifies the feeding preferences of Drosophila. Consequences for diet dependent hypoxic survival

The intakes rates of sucrose and yeast by normoxic or chronically hypoxic flies (5% O2) were analyzed under self selecting and "no choice" conditions. Chronically hypoxic flies fed on pure yeast diets or mixed diets under self selection conditions stopped feeding on yeast. Flies fed on mixed diets under "no choice" conditions reduced their food intakes. Hypoxia did not modify the adaptation of flies to diluted diets or to imbalanced diets. Mortality was assessed in parallel experiments. Dietary yeast had two distinct effects on hypoxic flies (i) a repellent action which eventually led to starvation and which was best observed in the absence of dietary sucrose and (ii) a toxic action which led to premature death. Finally we determined that hypoxic survivals were correlated to the intakes of sucrose, which suggested that dietary yeast killed flies by reducing their intake of sucrose. The feeding preferences of adult Drosophila were insensitive to NO scavengers, NO donor molecules and inhibitors of phosphodiesterases which are active on Drosophila larvae.Chronically hypoxic flies modify their feeding behavior. They avoid dietary yeast which appears to be toxic. Hypoxic survival is dependent on a source of exogenous sucrose. Ultimately, dietary yeast reduces hypoxic survival by reducing the intake of sucrose. The results highlight the importance of behavioral mechanisms in the responses of Drosophila to chronic hypoxic conditions.Increasing interest has been devoted to the relationships between diet, longevity, aging and resistance to various forms of stress. For instance different protocols of dietary restriction increase longevity in model organisms such as Drosophila melanogaster and Caenorhabditis elegans and in mammals. There is still much controversy about the molecular and physiological mechanisms involved [1-3]. Recent studies have highlighted the importance of feeding behavior in dietary effects [4,5]. Flies do not simply ingest calories. They sense different c