Baylor  醫(yī)學(xué)院分子和人類遺傳學(xué)教授Dr.  Hugo  Bellen發(fā)明了P(acman)  方法,  該方法能將DNA插入果蠅基因組,，克服了現(xiàn)在通用方法的關(guān)鍵障礙，能夠在活體條件下研究大片段DNA,，真正意義上實現(xiàn)研究果蠅全基因組結(jié)構(gòu)和功能的方法,。此外，該方法也可用于其它模式生物,，如小鼠的研究中,。研究成果刊登于11月30日Science雜志。

P/phiC31人工染色體（artificial  chromosome）,，或稱P(acman),，結(jié)合了三種最新技術(shù)：細(xì)菌人工染色體（bacterial  artificial  chromosome  ，BAC,，能夠使大片段DNA維持在細(xì)菌中）,、重組技術(shù)（recombineering）、能將大片段DNA插入果蠅基因組特定位點(diǎn)的phiC31-介導(dǎo)的轉(zhuǎn)基因技術(shù)（phiC31-mediated  transgenesis）,。

Bellen評價這是一項意義深遠(yuǎn)的新技術(shù),。P(acman)越過了阻礙研究的絆腳石，能夠?qū)⒖寺〉玫降拇笃蜠NA用于基因組轉(zhuǎn)化,，并且保證DNA片段插入基因組特異位點(diǎn),。目前研究基因機(jī)構(gòu)和功能的技術(shù)都存在這樣那樣的問題，比如研究人員培育缺少特定基因的果蠅時,，如果想將這種特定基因重新放入基因組中,，那么插入位點(diǎn)經(jīng)常是沒有規(guī)律的。

有時會產(chǎn)生過多的蛋白,，有時又產(chǎn)生的非常少,，還有些情況下，這些重新插回的基因會影響其它基因的表達(dá),。

“在做這些的時候如同拿蘋果和桔子相比,，”  Bellen。其它技術(shù)限于小的DNA片段,。“Koen（發(fā)育生物學(xué)BCM計劃一名研究生）利用這三種技術(shù)開發(fā)新的轉(zhuǎn)基因系統(tǒng),。”

細(xì)菌人工染色體（BAC），使科學(xué)家能夠?qū)⒋笃蜠NA維持在細(xì)菌中,，但是只有一個或少數(shù)幾個拷貝,。然而，細(xì)菌在必要時會產(chǎn)生許多DNA拷貝,。

因此,，Koen添加了重組（recombineering）技術(shù)。利用重組技術(shù)能夠很方便地克隆出大片段DNA,，并且可以在基因中的任意位點(diǎn)造成特異突變,。

第三種技術(shù)能夠幫助研究人員在果蠅基因組中尋找有潛力的突變基因,，消除蘋果－桔子的問題。這第三種技術(shù)－phiC31－在小鼠和人類細(xì)胞中也可以發(fā)揮功能,，提示這種新技術(shù)具有通用性,。

英文原文：

P(acman) Takes A Bite Out Of Deciphering Drosophila DNA

P(acman) - a new method of introducing DNA into the genome of fruit flies or Drosophila - promises to transform the ability of scientists to study the structure and function of virtually all the fly's genes, and the method may be applicable to other frequently studied organisms such as mice, said its Baylor College of Medicine developers in an article in the current issue of the journal Science.

"P(acman) overcomes a key limitation of currently available methods because it allows you to study large chunks of DNA in vivo," said Dr. Hugo Bellen, professor of molecular and human genetics at Baylor College of Medicine and director of the program in developmental biology. He is also a Howard Hughes Medical Institute investigator. The new technique allows researchers to study large genes and even gene complexes in the fruit fly, which was not possible before.

P/phiC31 artificial chromosome for manipulation, or P(acman), combines three recently developed technologies: a specially designed bacterial artificial chromosome (BAC) that allows maintenance of large pieces of DNA in bacteria, recombineering that allows the manipulation of large pieces of DNA that can then be inserted into the genome of the fly at a specific site using phiC31-mediated transgenesis.

It is a new technique with far-reaching promise, said Bellen.

P(acman) overcomes certain obstacles that have hampered research. It allows the cloning of large pieces of DNA to be used to transform the genome, and it permits that DNA to be inserted into specific places in the genome. Bellen credits the report's first author, Koen J.T. Venken, a graduate student in the BCM Program in Developmental Biology, with putting the technologies together to come up with a new methodology in the field.

Current technology has certain problems for researchers seeking to understand the structure and function of genes, said Bellen. Often, when scientists breed flies that lack a particular gene and then try to put that gene back into the fly, it inserts itself randomly into the genetic blueprint.

In some cases, it makes too much protein, and in others, too little. In other instances, it may disrupt the message from another gene.

"You are really comparing apples and oranges when you do this," said Bellen. The technique is also limited to small DNA chunks.

"Koen set out to develop a new transgenesis system using the three techniques," said Bellen.

The bacterial artificial chromosome, or BAC, he used allows the scientist to maintain large chunks of DNA in the bacteria, but it is present in only one or few copies. However, the bacteria can be induced to produce many copies of the DNA when needed.

Koen then integrated a technique called 'recombineering' into the strategy, which facilitates the scientist to clone large chunks of DNA and subsequently allows them to make specific mutations anywhere he or she wants in the gene.

The third technique allows the researcher to pinpoint where he or she wants to the mutant gene to go in the genetic blueprint of the fly, eliminating the apples-and-oranges problem. This third technique - phiC31 - works also in mouse and human cells, implying that this new technique could be used in those cells as well.