Meeting Abstract
Reprogramming of the core metabolism may be necessary during development of many holometabolous insects to generate sufficient energy for maintenance and meet demands of rapid growth. The underlying genetic architecture of an individual during this ontogeny may be crucial, influencing various biochemical and physiological factors that govern metabolic supply and demand. To investigate this, we characterized larval metabolic rate and aspects of glycolytic and mitochondrial physiology across development for a number of natural Drosophila melanogaster genotypes, as well as for mitochondrial-nuclear genotypes that combine naturally occurring polymorphisms from different species to generate energetic inefficiencies. The mass-scaling of metabolic rate differed significantly across instars and between genotypes. During development, early instars had significantly higher respiration per unit mass compared to late instars. Interestingly, this was in spite of significantly lower aerobic respiratory capacity of mitochondria in early instars. We also observed a metabolic switch during development away from oxidative phosphorylation to anaerobic ATP production, as measured by accumulation of lactate in the whole body of instars. It has been suggested that this reprogramming in D. melanogaster enables individuals to meet bioenergetics and biosynthetic demands of growth. However, there is genetic variation for the extent of metabolic reprogramming in all genotypes. Genotypes with compromised oxidative phosphorylation (OXPHOS) had significantly elevated lactate levels suggesting strong influence underlying genetic variation, including mitochondrial-nuclear genetic interactions (i.e., epistasis). This study demonstrates the diverse metabolic strategies used and the importance of genetic variation on the ontogeny of metabolism.
