Mammoth blood protein 'resurrected' by scientists
By Paul Rincon
Science reporter, BBC News
Page last updated at 20:30 GMT, Tuesday, 4 May 2010 21:30 UK
The mutation may have helped mammoths survive in the Ice Age突變可能有助於猛獁象在冰河時代生存
Scientists have discovered genetic mutations that allowed woolly mammoths to survive freezing temperatures.
Nature Genetics reports that scientists "resurrected" a mammoth blood protein to come to their finding.
This protein, known as haemoglobin, is found in red blood cells, where it binds to and carries oxygen.
The team found that mammoths possessed a genetic adaptation allowing their haemoglobin to release oxygen into the body even at low temperatures.
The ability of haemoglobin to release oxygen to the body's tissues is generally inhibited by the cold.
The researchers sequenced haemoglobin genes from the DNA of three Siberian mammoths, tens of thousands of years old, which were preserved in the permafrost.
The mammoth DNA sequences were converted into RNA (a molecule similar to DNA which is central to the production of proteins) and inserted into E. coli bacteria.
The bacteria faithfully manufactured the mammoth protein.
"The resulting haemoglobin molecules are no different than 'going back in time' and taking a blood sample from a real mammoth," said co-author Kevin Campbell, from the University of Manitoba in Canada.
Scientists then tested the "revived" mammoth proteins and found three distinctive changes in the haemoglobin sequence allowed mammoth blood to deliver oxygen to cells even at very low temperatures.
This is something the haemoglobin in living elephants cannot do.
"It has been remarkable to bring a complex protein from an extinct species back to life and discover important changes not found in any living species," said co-author Alan Cooper, director of the Australian Centre for Ancient DNA at the University of Adelaide.
Without their genetic adaptation, mammoths would have lost more energy in winter, forcing them to replace that energy by eating more.
The ancestors of woolly mammoths and modern-day elephants originated in equatorial Africa.
But between 1.2 and 2.0 million years ago, members of the mammoth lineage migrated to higher latitudes.
Writing in Nature Genetics, the scientists say that this genetic specialisation may have been crucial in allowing the ancestors of mammoths to exploit new, colder environments during Pleistocene times.
Paul.Rincon-INTERNET@bbc.co.uk
http://news.bbc.co.uk/2/hi/science/nature/8657464.stm
科學家成功再造猛?血液 《侏羅紀公園》成真？
2010年05月04日08:34
來源：新華網
迄今發現的保存最完整的猛?象尸體
猛?象又名長毛象，因全身長滿用以御寒的長毛而著稱，已於約1萬年前滅絕。加拿大科學家成功再造猛?象的血液，或許在未來可以讓這一物種重現地球。
遷移之謎
猛?象堪稱最負盛名的史前哺乳動物，其生存的時代為冰河世紀。猛?象與現存的非洲象和亞洲象是近親，最早都在赤道附近的非洲地區活動。大約120萬年至200萬年前，氣候變化導致氣溫驟降。猛?象遂向北半球高緯度遷移，在極地附近的冰原上覓食與生活。
猛?象的遷移行為令人費解，因為低溫會抑制象體內輸送氧氣的血紅蛋白，導致它們無法在寒冷氣候中生存。科學家由此猜測猛?象的血紅蛋白可能發生了變異。
加拿大馬尼托巴大學研究人員通過對比猛?象和現存非洲象、亞洲象的基因証實了這一猜測：猛?象具有遺傳適應能力，它們的血液基因發生了突變。即使在低溫環境中，猛?象的血紅蛋白也能輸送氧氣。
再造血液
在科幻小說《侏羅紀公園》中，從幾百萬年前的琥珀中提取出的昆虫脫氧核糖核酸(DN A )可以再造恐龍。這或許給科學家帶來了靈感。
馬尼托巴大學研究人員在西伯利亞的凍土層中找到三具約四萬年前的猛?象“遺體”，從它們的骨骼中提取出血紅蛋白D N A，按順序排列好，再將其轉錄為核糖核酸(RN A )並放入大腸杆菌中培養。
最終，猛?象的血紅蛋白在大腸杆菌中獲得“重生”。
相關研究成果刊登在最新一期《自然遺傳學》雜志上。
英國《每日郵報》2日援引研究報告作者之一、馬尼托巴大學教授凱文·坎貝爾的話報道： “這種合成的血紅蛋白取材於真實的猛?象標本，與猛?象活體體內的血紅蛋白沒有區別。”
有望復活
研究人員對再生血液進行檢測，發現血紅蛋白的排列順序發生了三處明顯改變，正是這種改變使猛?象的血液變得“抗凍”。現存的大象並不具備這種能力。
這種改變也表現在其他一些生活在北極地區的物種身上，比如馴鹿和麝香牛。科學家相信，借助這種遺傳適應技術能夠重建猛?象身體的其他部分，使其復活。
這項研究已經持續7年，參與其中的英國約克大學教授米基·霍夫賴特說：“這項研究是運用古老D N A再造滅絕物種的第一次探索，具有重要的進步意義和廣泛的適用性。”
但是再造出血液蛋白質並不意味著能夠重建動物的整個身體，因為D N A無法保存在化石中。對於恐龍這類幾百萬年前就已經滅絕的物種而言，科學家也回天乏術。
（責任編輯：劉向（實習））
http://scitech.people.com.cn/BIG5/11510546.html
科學家欲讓猛瑪象復活 稱“一切已准備就緒”
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