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Eurasia
hemoglobin
Nature Genetics
E. coli bacteria
Celsius
A couple million years ago, mammoths migrated north from Africa to colonize Eurasia. Sometime around then a massive ice age kicked in - and it was stay warm or die. So their tails and heat-shedding ears shrunk, and they grew thick coats of oily fur. But if you're out in the cold all day you also need some biochemical adjustments. Hemoglobin is the protein in red blood cells that delivers oxygen to your tissues. And it doesn't off-load oxygen well at low temperatures; it just clings to it more tightly. So mammoths solved that problem by evolving hemoglobin that releases oxygen more easily in the cold. That's according to a study published in the journal Nature Genetics. Researchers got the DNA that codes for hemoglobin from a 43,000-year-old mammoth. Then they used E. coli bacteria to produce actual mammoth hemoglobin. Then compared it to that of their living cousins, Asian elephants, at 37, 25 and 10 degrees Celsius. Due to just a few key structural changes, mammoth hemoglobin can release oxygen more readily at cold temperatures. Which was just the thing to help mammoths keep their cool.
数百万年前，猛犸象从非洲北部迁徙至亚欧殖民区。同样也是那个时代，大规模的冰河时代也降临了这片大陆。猛犸象所面临的的局面就只剩温暖的活着活冰冷的死去。为了适应生态环境，猛犸象的尾巴和用于散热的耳朵逐渐收缩，而它们的皮毛外套则逐渐增厚。 但是如果它们一整天都要呆在野外的话，那它们就必须做出一些生物化学调整。血红蛋白是一种存在于红血细胞内的蛋白质，它们所起到的作用是将氧气输送到身体组织。在低温环境下，血红蛋白与氧气更为紧密的结合在一起，所以并不能十分有效的将氧气输送到各身体组织。而猛犸象通过溶解血红细胞来使氧气在低温环境下更易释放。这一结论源自于一篇发布在自然遗传学的研究报告。 研究人员从一头43，000岁的猛犸象上提取了与血红蛋白相关的DNA，然后他们利用大肠杆菌来制造出真正的猛犸象血红蛋白，并将此与其近亲亚洲象的血红蛋白来进行比较，比较的设定温度分别为摄氏37,25和10度。研究表明，由于2者之间一些较为关键的结构性变化，所以造成猛犸象的血红蛋白可以在低温下更稳定地释放更多的氧气。而这才是猛犸象抵御寒冬的关键秘诀所在。 ——译文来自: sleep878