The “Direct Connection” section of MolBio Research Highlights includes blog posts discussing primary research articles in the field, but the interesting thing about it is that these posts are written by the authors themselves. This allows them to discuss the background, results and implications of their work with a wider audience and in a more relaxed format. Further, as it provides a direct link between the authors and the scientific community (hence its name), it promotes discussion. In today's "Direct Connection", Christopher Dieni, PhD, a postdoctoral scholar in the Department of Chemistry at Pennsylvania State University, discusses his recent publication entitled "Regulation of Glucose-6-Phosphate Dehydrogenase by Reversible Phosphorylation in Liver of a Freeze Tolerant Frog".
Sweet and Sour: Glucose-6-Phosphate, Anoxia, and Enzyme Regulation
A crazy model organism!
Grad school taught me a great many lessons, but I think many of them can be summarized in a brief and blunt statement: human beings aren’t that great!
Shocked?
Well, when you think about it, we’re not that cool of an organism at all. We’re extremely inefficient (biochemically speaking), and we’re really not that adaptable to… well… anything that perturbs our internal or external environment, however slight. By stark contrast, my graduate lab, or more accurately the lab of Dr. Ken Storey at Carleton University in Ottawa, Ontario, Canada, studies a wide array of awesome animals -model organisms- that can withstand harsh environmental conditions. These include frogs and snails that survive the desert heat and dehydration, mammals that hibernate over the long winter, reptiles and amphibians that can get by for months on an oxygen-deprived environment and my personal favorite and the central model organism of my graduate work, the freeze-tolerant wood frog, Rana sylvatica, that can survive the freezing of ~70% of its extracellular and extra-organ water during the winter, and then thaw in the spring and continue about its normal life.
A notable thing about the wood frog’s survival mechanisms is that one molecule plays a key role in keeping the frog alive during its frozen, unfathomable state: glucose. Most people find it hard to believe that this simple and ubiquitous six-carbon sugar can have such a prominent role in this extraordinary organism and yet, evolutionarily speaking, it makes perfect sense. Take a molecule with such universality and harness it maximally, not only for its biochemical and metabolic properties, but for its physical properties as well. High intracellular glucose can act as a cryoprotectant, as it prevents both intracellular freezing and the loss of intracellular water to the extracellular environment caused by the osmotic imbalance of extracellular freezing.
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