Schulte 2013 Abstract MiP2013

Chung DJ, Schulte PM, Richards JG (2013) The effect of low-temperature acclimation on mitochondrial function in the common killifish (Fundulus heteroclitus), a top-down elasticity analysis. Mitochondr Physiol Network 18.08.

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MiP2013, Book of Abstracts Open Access

Chung DJ, Schulte PM, Richards JG (2013)

Event: MiPNet18.08_MiP2013

Based on its presumed role in altering whole-animal metabolic rate, the mitochondrion has become the focus of hypotheses that address the process of thermal adaptation. It has been proposed that temperature-induced limitations on mitochondrial function (due to passive thermal effects on biochemical activity or an imbalance between O2 supply and demand at low temperatures) affect whole organism performance and, as a result, cold-adapted or –acclimated species compensate with increased mitochondrial density and/or activity [1]. To address this hypothesis we use Fundulus heteroclitus, a teleost species with genetically distinct, locally adapted subpopulations (Northern, Southern, and Hybrid) which reside over a large thermal gradient. During acute high temperature shifts (37 °C), liver mitochondria isolated from 5 °C acclimated Northern Fundulus heteroclitus lose the capacity to perform oxidative phosphorylation. This phenomenon is not observed with fish acclimated to 15 and 25 °C, which is indicative of a cost of acclimation to low temperatures [2].

To investigate the functional differences in mitochondrial properties as a result of low temperature acclimation we have acclimated Northern and Southern Fundulus heteroclitus to 5, 15 and 33 °C. We compare the kinetics of liver mitochondrial ADP-phosphorylation, proton conductance, and substrate oxidation during acute shifts to 5, 15, and 33 °C. In addition, we compare the rates of basal and maximum reactive oxygen species (ROS) production to assess its contribution as a result of proton conductance.

Our current results indicate that during acute shifts to high temperature, cold-acclimated Northern killifish exhibit equivalent levels of LEAK respiration (i.e., proton leak) as room- and warm-temperature acclimated killifish while maintaining a lower membrane potential. This equivalent level of proton leak is reflected in no difference in ROS production when compared to the 15 °C acclimation. In addition, warm-acclimation appears to result in increased basal ROS production, while lowering maximal ROS. These results indicate that there are changes in mitochondrial function associated with low-temperature acclimation.

• O2k-Network Lab: CA Vancouver Richards JG

Labels: MiParea: Respiration, Comparative MiP;environmental MiP 

Stress:Oxidative stress;RONS  Organism: Fishes  Tissue;cell: Liver  Preparation: Isolated mitochondria 

Regulation: mt-Membrane potential, Temperature  Coupling state: LEAK, OXPHOS 

HRR: Oxygraph-2k 

MiP2013, S04 

Affiliations and author contributions

Department of Zoology, University of British Columbia; Vancouver, Canada. - Email: [email protected]

References

1. Pörtner HO (2010) Oxygen- and capacity-limitation of thermal tolerance: a matrix for integrating climate-related stressor effects in marine ecosystems. J Exp Biol 213: 881-893.
2. Fangue NA, Richards JG, Schulte PM (2009) Do mitochondrial properties explain intraspecific variation in thermal tolerance? J Exp Biol 212: 514–522.