How do animals decide when to stop growing and become adults? Body size profoundly affects many aspects of animal biology, yet the mechanisms by which animals determine their adult size remain among the fundamental unsolved problems of developmental biology. Holometabolous insects - the primary model for the study of size regulation in animals - do not grow as adults, so the size at which larvae initiate metamorphosis determines their adult size. A recent prominent hypothesis is that "the proximate mechanism setting limits to size during [larval] development is probably the onset of cellular hypoxia", presumably due to oxygen demand outstripping supply capacity. This research will test the role of oxygen in determination of adult body size in the fruit fly, Drosophila melanogaster, by examining the effect of manipulation of atmospheric oxygen levels on growth, timing of metamorphosis, and neuroendocrine function. In addition, epigenetic analyses will be conducted to test the role of candidate signaling pathways by which oxygen sensing might control developmental timing and body size.
Understanding how body size is determined is a fundamental question of biology because body size affects so many aspects of physiology, ecology and evolution. Body size strongly affects food requirements, competitive and reproductive capacities, value as a resource, drug clearance rates, and stress-tolerance of an animal. Yet, the mechanisms involved in determining when animals switch from the growing juvenile form to the reproductive adult form are not well-understood for any animal. In addition to providing new information on this topic that may be general for animals, this research with Drosophila may have specific applications relevant to insect control for agriculture and disease-prevention. This research will contribute to science training by funding research experiences for undergraduate, graduate and postdoctoral trainees. Finally, this project will support secondary education by development of an on-line biology laboratory and outreach to a local bioscience-focused high school. Results from this project will also be disseminated through peer reviewed publications and presentations at regional or national scientific meetings. Data associated with each publication will be posted on Dryad (www.datadryad.org).
