PMID- 16155230
OWN - NLM
STAT- MEDLINE
DCOM- 20060316
LR  - 20101118
IS  - 0022-0949 (Print)
IS  - 0022-0949 (Linking)
VI  - 208
IP  - Pt 18
DP  - 2005 Sep
TI  - Allometric scaling of flight energetics in orchid bees: evolution of flux 
      capacities and flux rates.
PG  - 3593-602
AB  - The evolution of metabolic pathways involved in energy production was studied in 
      the flight muscles of 28 species of orchid bees. Previous work revealed that 
      wingbeat frequencies and mass-specific metabolic rates decline in parallel by 
      threefold as body mass increases interspecifically over a 20-fold range. We 
      investigated the correlated evolution of metabolic rates during hovering flight 
      and the flux capacities, i.e. V(max) values, of flight muscle enzymes involved in 
      substrate catabolism, the Krebs cycle and the electron transport chain. V(max) at 
      the hexokinase (HK) step scales allometrically with an exponent almost identical 
      to those obtained for wingbeat frequency and mass-specific metabolic rate. 
      Analysis of this relationship using phylogenetically independent contrasts 
      supports the hypothesis of correlated evolution between HK activity and 
      mass-specific metabolic rate. Although other enzymes scale allometrically with 
      respect to body mass, e.g. trehalase, glycogen phosphorylase and citrate 
      synthase, no other enzyme activities were correlated with metabolic rate after 
      controlling for phylogenetic relatedness. Pathway flux rates were used with 
      enzyme V(max) values to estimate fractional velocities (fraction of V(max) at 
      which enzymes operate) for various reactions to gain insights into enzyme 
      function and how this varies with body mass. Fractional velocity is highly 
      conserved across species at the HK step, but varied at all other steps examined. 
      These results are discussed in the context of the regulation and evolution of 
      pathways of energy metabolism.
FAU - Darveau, Charles-A
AU  - Darveau CA
AD  - Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, 
      Canada. darveau@zoology.ubc.ca
FAU - Hochachka, Peter W
AU  - Hochachka PW
FAU - Roubik, David W
AU  - Roubik DW
FAU - Suarez, Raul K
AU  - Suarez RK
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - J Exp Biol
JT  - The Journal of experimental biology
JID - 0243705
RN  - 0 (Enzymes)
SB  - IM
MH  - Animals
MH  - Bees/metabolism/*physiology
MH  - *Biological Evolution
MH  - Cell Respiration/physiology
MH  - Energy Metabolism/*physiology
MH  - Enzymes/*metabolism
MH  - Flight, Animal/*physiology
MH  - Mitochondria/metabolism
MH  - Muscles/enzymology/*physiology
MH  - Panama
MH  - Spectrophotometry, Ultraviolet
EDAT- 2005/09/13 09:00
MHDA- 2006/03/17 09:00
CRDT- 2005/09/13 09:00
PHST- 2005/09/13 09:00 [pubmed]
PHST- 2006/03/17 09:00 [medline]
PHST- 2005/09/13 09:00 [entrez]
AID - 208/18/3593 [pii]
AID - 10.1242/jeb.01777 [doi]
PST - ppublish
SO  - J Exp Biol. 2005 Sep;208(Pt 18):3593-602. doi: 10.1242/jeb.01777.