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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.
數(shù)百萬年前，猛犸象從非洲北部遷徙至亞歐殖民區(qū)。同樣也是那個(gè)時(shí)代，大規(guī)模的冰河時(shí)代也降臨了這片大陸。猛犸象所面臨的的局面就只剩溫暖的活著活冰冷的死去。為了適應(yīng)生態(tài)環(huán)境，猛犸象的尾巴和用于散熱的耳朵逐漸收縮，而它們的皮毛外套則逐漸增厚。 但是如果它們一整天都要呆在野外的話，那它們就必須做出一些生物化學(xué)調(diào)整。血紅蛋白是一種存在于紅血細(xì)胞內(nèi)的蛋白質(zhì)，它們所起到的作用是將氧氣輸送到身體組織。在低溫環(huán)境下，血紅蛋白與氧氣更為緊密的結(jié)合在一起，所以并不能十分有效的將氧氣輸送到各身體組織。而猛犸象通過溶解血紅細(xì)胞來使氧氣在低溫環(huán)境下更易釋放。這一結(jié)論源自于一篇發(fā)布在自然遺傳學(xué)的研究報(bào)告。 研究人員從一頭43，000歲的猛犸象上提取了與血紅蛋白相關(guān)的DNA，然后他們利用大腸桿菌來制造出真正的猛犸象血紅蛋白，并將此與其近親亞洲象的血紅蛋白來進(jìn)行比較，比較的設(shè)定溫度分別為攝氏37,25和10度。研究表明，由于2者之間一些較為關(guān)鍵的結(jié)構(gòu)性變化，所以造成猛犸象的血紅蛋白可以在低溫下更穩(wěn)定地釋放更多的氧氣。而這才是猛犸象抵御寒冬的關(guān)鍵秘訣所在。 ——譯文來自: sleep878