Biologist Craig Venter and his team replicated a bacterium's genetic structure entirely from laboratory chemicals, moving one step closer to creating the world's first living artificial organism.

    The scientists assembled the synthetic genome by stringing together chemicals that are the building blocks of DNA. The synthetic genome was constructed so it included all the genes that would be found in a naturally occurring bacterium.

    The research was published in the online version of the journal Science by a team of scientists from the J. Craig Venter Institute in Rockville, Md. The authors include Hamilton Smith, who won the Nobel Prize for Medicine in 1978.

    'It's the second significant step of a three-step process to create a synthetic organism,' said Dr. Venter, in a conference call with reporters. The final step could prove far trickier, though Dr. Venter defied his critics and deciphered the human genome with startling speed about eight years ago.

    The larger quest is to make artificial life forms with a minimum set of genes necessary for life. It is hoped that such organisms could one day be engineered to perform commercial tasks, such as absorbing carbon dioxide from the air or churning out biofuels.

    The scientific challenge of creating synthetic life isn't trivial, nor are the ethical and legal concerns. There is little government oversight, and researchers involved in such experiments regulate themselves. Detractors worry that the lack of safeguards increases the risks that a potentially dangerous man-made organism might run amok. (In creating the artificial genome of Mycoplasma, Dr. Venter's team disrupted the genes that would enable it to infect other organisms.)

    Nonetheless, the science is pushing forward at a rapid pace. In June, a Venter-led team published details of an experiment in which it inserted the DNA of one species of bacteria into the cells of another bacteria species. That process almost magically 'booted up' the genome of the donor bacteria, sparking it to life.

    The team hopes to use a similar trick to boot up the artificially created genome, to create a man-made living organism. But, Dr. Venter said, 'there are multiple barriers' to achieving that goal.

    Dr. Venter now believes that the challenge of creating a synthetic organism is within his grasp. 'I'll be. . . disappointed if we can't do it in 2008,' he said.

    美國(guó)生物學(xué)家克雷格•文特(Craig Venter)以及他帶領(lǐng)的研究小組日前完全利用實(shí)驗(yàn)室化學(xué)物質(zhì)復(fù)制出了一種細(xì)菌的基因組，向創(chuàng)造首個(gè)人造生命又邁進(jìn)了一步。

    科學(xué)家們將實(shí)驗(yàn)室化學(xué)物質(zhì)作為脫氧核糖核酸(DNA)的基因塊串列在一起，從而合成出了基因組。而人造基因組的基因都可以在天然細(xì)菌體內(nèi)找到與其對(duì)應(yīng)的部分。

    這項(xiàng)研究成果由馬里蘭州克雷格•文特研究院(J. Craig Venter Institute)的一組科學(xué)家刊登在《科學(xué)》(Science)雜志網(wǎng)絡(luò)版上。署名作者包括1978年諾貝爾醫(yī)學(xué)獎(jiǎng)獲得者漢密爾頓•史密斯(Hamilton Smith).

    文特在與記者舉行的電話會(huì)議上表示，創(chuàng)造人造生命的實(shí)驗(yàn)分三個(gè)階段，而此次成功標(biāo)志著第二階段的完成，但最后這一步的難度會(huì)大得多。不過他在大約八年前曾頂住外界異議，以驚人的速度破譯了人類基因組。

    一個(gè)更大的問題在于要讓人造生命攜帶有使其存活下來最起碼的基因組。預(yù)計(jì)此類生物有朝一日能應(yīng)用在商業(yè)領(lǐng)域上，例如吸收空氣中的二氧化碳或提煉生物燃料。

    廣告向人造生命領(lǐng)域發(fā)起挑戰(zhàn)在科學(xué)上面臨著不小的難度，而且在倫理和法律方面也有很多問題。目前幾乎沒有政府對(duì)此類研究進(jìn)行管理，參與實(shí)驗(yàn)的研究人員都是依靠自律。而中傷這項(xiàng)研究的人聲稱，安全保障的缺失將增加人造生命釀成大禍的風(fēng)險(xiǎn)（文特率領(lǐng)的研究小組在合成支原菌基因組時(shí)，有意破壞了賦予染色體感染其他生物的能力的基因）。

    盡管如此，研究正在迅速向前推進(jìn)。去年6月，由文特率領(lǐng)的一個(gè)研究小組公開了一項(xiàng)實(shí)驗(yàn)的詳細(xì)情況。在這項(xiàng)實(shí)驗(yàn)中，他們將一種細(xì)菌的DNA移植到另一種細(xì)菌的細(xì)胞中，并近乎奇跡般的“激活”了被植入的基因組。

    研究小組希望采用類似的方法能激活人造的基因組，從而創(chuàng)造出一種人造生命。不過文特表示，在成功的道路上還存在許多障礙。

    但文特相信，現(xiàn)在距離大功告成只有一步之遙。他對(duì)此表示，如果無法在2008年取得成功……將是一件令人失望的事情。