澳大利亞科學(xué)家從鳥(niǎo)類蛋殼化石中成功提取出DNA樣本，為復(fù)原象鳥(niǎo),、恐鳥(niǎo)等已經(jīng)滅絕的巨鳥(niǎo)奠定了基礎(chǔ)，距離科幻大片《侏羅紀(jì)公園》所描述的場(chǎng)景又近了一步,。
研究人員表示,，成功從蛋殼中提取DNA樣本，“在考古學(xué)和古生物學(xué)研究領(lǐng)域均具有重大意義”,。澳大利亞莫道克大學(xué)生物學(xué)家夏洛特·奧斯卡姆(Charlotte Oskam)和同事表示,，蛋殼是一種具有良好遺傳物質(zhì)恢復(fù)性的薄膜，在世界各地的化石沉積物中經(jīng)常被發(fā)現(xiàn),，而他們從蛋殼中提取DNA樣本的研究在全球范圍內(nèi)尚屬首例,。研究結(jié)果刊登在英國(guó)《皇家學(xué)會(huì)學(xué)報(bào)B輯—生物科學(xué)》（Proceedings of the Royal Society B: Biological Sciences）上。
奧斯卡姆的研究小組通過(guò)先進(jìn)的激光技術(shù),，利用綠色熒光染料在顯微鏡下鎖定DNA“熱區(qū)”,。他們說(shuō)：“我們的研究顯示，遺傳物質(zhì)保存于蛋殼母體中，利用顯微鏡技術(shù)成功拍下DNA照片,。通過(guò)最新技術(shù),，我們可以從各種各樣的蛋殼化石中提取DNA樣本，包括已經(jīng)滅絕的恐鳥(niǎo),、象鳥(niǎo)以及具有1.9萬(wàn)年歷史的鴯鹋(亦稱澳洲鴕鳥(niǎo)),。”
象鳥(niǎo)站高10英尺(約合3.05米)，重1000磅(約合454公斤),，是鴕鳥(niǎo)和鴯鹋的近親,，也是迄今曾在地球上出現(xiàn)的最大鳥(niǎo)類。腿部粗壯,，頸部長(zhǎng)而有力,，身體覆蓋豎立的、像頭發(fā)一樣的羽毛,，就像鴯鹋一樣,，喙部類似寬頭長(zhǎng)矛。象鳥(niǎo)進(jìn)化時(shí)恰逢鳥(niǎo)類統(tǒng)治地球的輝煌時(shí)期,，可能在馬達(dá)加斯加島生活了6000萬(wàn)年之久,，直至17世紀(jì)滅絕。雖然模樣嚇人,，象鳥(niǎo)其實(shí)是食草動(dòng)物,，只吃植物。
恐鳥(niǎo)是另一種不會(huì)飛的巨鳥(niǎo),，曾經(jīng)生活在新西蘭,，由于遭到當(dāng)?shù)赝林说拇笏敛稓ⅲ鼈兘K在18世紀(jì)從地球上消失,。鴯鹋是世界現(xiàn)存的第二大鳥(niǎo)類,，已在澳大利亞生活了8000萬(wàn)年之久，主要分布于沙漠,、森林和平原地區(qū),。奧斯卡姆和同事表示：“我們成功從在新西蘭、馬達(dá)加斯加島和澳大利亞發(fā)現(xiàn)的遠(yuǎn)古鳥(niǎo)類蛋殼中提取出DNA樣本,。我們的數(shù)據(jù)表明這些樣本保存極為完好,。”
鳥(niǎo)類蛋殼具有良好的遺傳物質(zhì)恢復(fù)性，可以有效承受氧氣和水的侵蝕,，而氧氣和水是造成DNA破壞的主要原因,。研究人員補(bǔ)充說(shuō)：“這項(xiàng)研究首次證明古代DNA分子能夠完好保存于鳥(niǎo)類蛋殼化石中。顯然,，蛋殼母體中保存的生物分子可以是以前未得到確認(rèn)和利用的DNA來(lái)源,，對(duì)這些DNA來(lái)源的特征描述對(duì)考古學(xué)和古生物學(xué)以及古物保存和法醫(yī)應(yīng)用都具有重大意義,。”(生物谷Bioon.com)
生物谷推薦原文出處：
Proceedings of the Royal Society B: Biological Sciences doi: 10.1098/rspb.2009.2019
Fossil avian eggshell preserves ancient DNA
Charlotte L. Oskam1, James Haile2,3, Emma McLay1, Paul Rigby4, Morten E. Allentoft1,5, Maia E. Olsen3, Camilla Bengtsson3, Gifford H. Miller6,7, Jean-Luc Schwenninger8, Chris Jacomb9, Richard Walter9, Alexander Baynes10, Joe Dortch11, Michael Parker-Pearson12, M. Thomas P. Gilbert3, Richard N. Holdaway5, Eske Willerslev3 and Michael Bunce1,*
Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes.
