Lecture 10.2: Paper 3 – Brand et al., 2003) Proton Conductance and Fatty Acyl Composition of Liver Mitochondria Correlates with Body Mass in Birds Flashcards
How can the physiology of mitochondria be assessed?
mitochondria are easily isolated from cells and their physiology assessed by monitoring O2 consumption rate under different conditions
Figure 1: Dependence of the Respiration Rate of Isolated Liver Mitochondria on Body Mass in Different Species of Birds
- in general, liver mitochondria from the LARGER species had LOWER respiration rates (per mg of mitochondrial protein) than those from the smaller species
What is the respiration control ratio?
shows how good the coupling in ATP production is
Figure 3: Comparison of the Kinetics of Proton Leak in Liver Mitochondria Isolated from Different Species of Birds
- mitochondria from SMALLER species had the HIGHEST proton leak rates, and those from the larger species tended to have progressively lower rates of proton leak at any particular driving force
Figure 4: Allometric Relationship Between Mitochondrial Proton Leak Rate at 170 mV and Either Body Mass or Mass-specific Standard Metabolic Rate for Different Bird Species
- mitochondria from SMALLER birds, have HIGHER proton leak than mitochondria from larger birds
Figure 5: Allometric Relationship Between Log Body Mass and Log Mole Fraction of Total Unsaturated, Monounsaturated, and Polyunsaturated Phospholipid Acyl Chains in Liver Mitochondria from Different Bird Species
- smaller birds have more polyunsaturated fatty acids (PUFA) in mitochondrial membrane
- larger birds have more monounsaturated fatty acids (MUFA) in mitochondrial membrane
How do membranes act at the metabolic pacemaker?
- mitochondria from smaller birds, which have more unsaturated membranes, have higher proton leak than mitochondria from larger birds
- related to mass-specific metabolic rates in smaller birds
- leaky membranes are associated with higher metabolic rates
