Turnover rates of mitochondrial respiratory chain enzymes in plying honeybees (Apis mellifera)

Metabolic rates (VCO2) of 32 worker honeybees were determined during agitat ed flight in a flow-through respirometry chamber. Because honeybees oxidize carbohydrate during flight and display respiratory exchange ratios equal t o 1.0, these measured VCO2 values equal VO2. The latter were used to estima te mitochondrial electron transport rates per unit thorax mass during fligh t. Dual wavelength spectroscopy was used to estimate cytochrome content per unit thorax mass in each individual used for respirometry. Electron flux r ate divided by cytochrome content yielded cytochrome turnover rate for each individual. Honeybees possess high cytochrome contest and display higher r ates of cytochrome turnover during flight than mammalian cardiac and skelet al muscles during maximum aerobic work. The significance of this finding is discussed in relation to the control of respiration and the factors that m ay set the upper limits to aerobic capacities in muscles. J. Exp. Zool. 284 :1-6, 1999. (C) 1999 Wiley-Liss, Inc.