Lifetime and castespecific changes in flight met

Authors: MariePierre Schippers Reuven Dukas Grant B McClelland

Publish Date: 2009/07/04

Volume: 180, Issue: 1, Pages: 45-

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Abstract

Honeybees Apis mellifera who show temporal polyethism begin their adult life performing tasks inside the hive hive bees and then switch to foraging when they are about 2–3 weeks old foragers Usually hive tasks require little or no flying whereas foraging involves flying for several hours a day and carrying heavy loads of nectar and pollen Flight muscles are particularly plastic organs that can respond to use and disuse and accordingly it would be expected that adjustments in flight muscle metabolism occur throughout a bee’s life We thus investigated changes in lifetime flight metabolic rate and flight muscle biochemistry of differently aged hive bees and of foragers with varying foraging experience Rapid increases in flight metabolic rates early in life coincided with a switch in troponin T isoforms and increases in flight muscle maximal activities V max of the enzymes citrate synthase cytochrome c oxidase hexokinase phosphofructokinase and pyruvate kinase However further increases in flight metabolic rate in experienced foragers occurred without additional changes in the in vitro V max of these flight muscle metabolic enzymes Estimates of in vivo flux v compared to maximum flux of each enzyme in vitro fractional velocity v/V max suggest that most enzymes operate at a higher fraction of V max in mature foragers compared to young hive bees Our results indicate that honeybees develop most of their flight muscle metabolic machinery early in life Any further increases in flight metabolism with age or foraging experience are most likely achieved by operating metabolic enzymes closer to their maximal flux capacityThe authors would like to thank Paul Kelly and Heather Mattila University of Guelph as well as Les Simonffy for generous assistance with bees Richard Smith McMaster University Todd Gillis and Jordan Klaiman University of Guelph for technical advice on troponin T as well as the McMaster Regional Centre for Mass Spectrometry for protein identification This study was supported by the Natural Sciences and Engineering Research Council of Canada Canada Foundation for Innovation and Ontario Innovation Trust to GB McClelland and R Dukas GB McClelland was supported by an Early Researcher Award from the Ontario Ministry of Research and Innovation MP Schippers was the recipient of an NSERC postgraduate scholarship

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