What is it about?
In the face of fluctuating environmental temperatures, animals must rapidly alter physiology to maintain function. Globally, metabolic enzymes vary genetically, seemingly in correspondence with environmental temperatures (for example, the degree of stressful cold experienced). However, the extent to which this genetic variation influences energy flow during stressful temperature exposures was previously unknown. Using the fly Drosophila melanogaster, we demonstrated that nutrient flow through metabolic pathways was enhanced in cold adapted flies, enabling them to rapidly prepare for and recover from cold exposure. This increased metabolic turnover raised their metabolic costs, suggesting that stress hardiness may trade-off against other energy-demanding activities.
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Why is it important?
Many studies have inferred that changes in temperature across the globe have reshaped metabolism based on alterations to enzymes, or steady state levels of metabolites. However, this is the first study to show that nutrient flow through metabolic pathways is impacted by exposure to extreme low temperatures.
Perspectives
Metabolic cold adaptation is a long-standing but contentious hypothesis, that posits that organisms from cold environments will have raised metabolic rates compared to warm-adapted counterparts. It has been contentious largely because the selection pressures that would lead to high metabolic rates in cold environments have not been clearly demonstrated - what benefit arises to an organism of having a high metabolic rate, when metabolic rates represent an energy cost? Here we demonstrate a clear benefit to high metabolic flux - more metabolic flexibility to facilitate rapid recovery from cold. I think this demonstrates that extreme temperatures can be equally important as average temperatures in driving physiological evolution.
Dr Caroline M Williams
University of California Berkeley
Read the Original
This page is a summary of: Cold adaptation increases rates of nutrient flow and metabolic plasticity during cold exposure inDrosophila melanogaster, Proceedings of the Royal Society B Biological Sciences, September 2016, Royal Society Publishing,
DOI: 10.1098/rspb.2016.1317.
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