Extremophile: Difference between revisions
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== Positively charged myoglobin allows whales to hold their breath during long dives == | == Positively charged myoglobin allows whales to hold their breath during long dives == | ||
Elephants can hold their breath for 2 minutes, but whales can hold their breath for 60 minutes - and they do, migrating underwater around the world. To get a clue as to why whales can hold their breath for so long, several researchers gathered tissue samples from hundreds of aquatic and terrestrial mammalian species (mainly from museum collections)<ref name="whaleMyo"> DOI:10.1126/science.1234192</ref>. They measured the concentration of [[myoglobin]], the protein that stores oxygen in muscle tissue for | Elephants can hold their breath for 2 minutes, but whales can hold their breath for 60 minutes - and they do, migrating underwater around the world. To get a clue as to why whales can hold their breath for so long, several researchers gathered tissue samples from hundreds of aquatic and terrestrial mammalian species (mainly from museum collections)<ref name="whaleMyo"> DOI:10.1126/science.1234192</ref>. They measured the concentration of [[myoglobin]], the protein that stores oxygen in muscle tissue, which is used for muscle activity, and also sequenced each specie's myoglobin gene, and used this sequence - as well as the protein's mobility on a native gel (which depends soley on structure and charge - with myoglobin from different species all having the same structure), when possible - to calculate the net charge of each myoglobin protein. | ||
Amazingly, they found that independently, aquatic mammals across the mammalian phylogeny had acquired their ability to hold their breath, by increasing the concentration of myoglobin, through increasing the net charge of myoglobin. In real values, typically, terrestrial mammal's myoglobin has a solubility of 20 mg/g tissue ([[http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/2/m0630pis.pdf Sigma Aldrich]]) and that is the level of myoglobin found in most terrestrial mammal's tissue. But whales and other aquatic mammals far exceed this solubility limit - whales have 70 mg/g - and this overcoming the solubility constraint may be traced back to an increase in the net charge of myoglobin - from around +2 in terrestrial animals to around +4 in aquatic animals. | Amazingly, they found that independently, aquatic mammals across the mammalian phylogeny had acquired their ability to hold their breath, by increasing the concentration of myoglobin, through increasing the net charge of myoglobin. In real values, typically, terrestrial mammal's myoglobin has a solubility of 20 mg/g tissue ([[http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/2/m0630pis.pdf Sigma Aldrich]]) and that is the level of myoglobin found in most terrestrial mammal's tissue. But whales and other aquatic mammals far exceed this solubility limit - whales have 70 mg/g - and this overcoming the solubility constraint may be traced back to an increase in the net charge of myoglobin - from around +2 in terrestrial animals to around +4 in aquatic animals. | ||
