生物谷：細菌等微生物之間的橫向基因轉(zhuǎn)移（lateral gene transfer）現(xiàn)象頻繁發(fā)生,，這對于它們的進化發(fā)展至關(guān)重要。美國科學(xué)家最新研究發(fā)現(xiàn),，細菌也能將基因轉(zhuǎn)移到復(fù)雜有機體中去,。這將促使科學(xué)家重新思考種間基因轉(zhuǎn)移在進化中的作用，也使得遺傳學(xué)家今后在為新基因組排序時,，不得不采用新的方法以過濾掉細菌基因的污染,。相關(guān)論文8月30日在線發(fā)表于《科學(xué)》上。
一直以來,，科學(xué)家認為細菌和多細胞有機體之間的基因轉(zhuǎn)移是很少見的,。已知僅有的幾個例子包括某種寄生細菌（Wolbachia）的基因能夠轉(zhuǎn)移到昆蟲及其它無脊椎動物體內(nèi)。
在最新實驗中，美國奎格文特研究所（J. Craig Venter Institute）的Julie Dunning Hotopp和同事對從昆蟲基因組中發(fā)現(xiàn)的Wolbachia基因序列展開了研究,。他們根據(jù)動物遺傳數(shù)據(jù)庫篩選Wolbachia的基因序列,，結(jié)果在三種黃蜂和四種蠕蟲基因組中發(fā)現(xiàn)了Wolbachia的基因序列。在黃蜂中,，這些基因序列有96%與黃蜂生存地的Wolbachia DNA相匹配,。
在另外的實驗中，研究人員用抗生素處理一種熱帶果蠅（Drosophila ananassae）的卵巢,，在確保Wolbachia基因序列來自該種果蠅基因組后,，將這種果蠅基因重新排序，結(jié)果驚訝地發(fā)現(xiàn)這種果蠅的一個染色體上含有幾乎整個Wolbachia基因組,，超過一百萬個DNA堿基對,。這些DNA中絕大多數(shù)已經(jīng)喪失功能，不過研究人員從30個Wolbachia基因中發(fā)現(xiàn)了RNA副本,，這表明這些基因曾被轉(zhuǎn)錄過,，已經(jīng)邁出了蛋白質(zhì)制造的第一步。
日本東京大學(xué)的進化生物學(xué)家Takema Fukatsu認為,，橫向轉(zhuǎn)移可能比我們先前預(yù)想的要廣泛得多,。他表示，此次研究結(jié)果激動人心,，但是問題是Wolbachia基因是否具有活性,，因為它們并沒有表現(xiàn)出任何的生物學(xué)功能。如果將來有實驗確認了這些基因能夠進行表達,，那么這將是對進化過程的一個空前的認識?。茖W(xué)網(wǎng) 梅進/編譯）
原始出處:
Published Online August 30, 2007
Science DOI: 10.1126/science.1142490
Submitted on March 13, 2007
Accepted on July 2, 2007
Widespread Lateral Gene Transfer from Intracellular Bacteria to Multicellular Eukaryotes
Julie C. Dunning Hotopp 1*, Michael E. Clark 2, Deodoro C. S. G. Oliveira 2, Jeremy M. Foster 3, Peter Fischer 4, Mónica C. Muñoz Torres 5, Jonathan D. Giebel 2, Nikhil Kumar 1, Nadeeza Ishmael 1, Shiliang Wang 1, Jessica Ingram 3, Rahul V. Nene 1, Jessica Shepard 1, Jeffrey Tomkins 5, Stephen Richards 6, David J. Spiro 1, Elodie Ghedin 7, Barton E. Slatko 3, Hervé Tettelin 1, John H. Werren 2
1 The Institute for Genomic Research, J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, MD 20850, USA.
2 Department of Biology, University of Rochester, Rochester, NY 14627, USA.
3 Molecular Parasitology Division, New England Biolabs Inc., 240 County Road, Ipswich, MA 01938, USA.
4 Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO 63110, USA.
5 Clemson University Genomics Institute, 304 BRC, 51 New Cherry St, Clemson, SC 29634, USA.
6 Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.
7 The Institute for Genomic Research, J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, MD 20850, USA.; Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
* To whom correspondence should be addressed.
Julie C. Dunning Hotopp , E-mail: [email protected]
These authors contributed equally to this work.
Present address: Brown University, Providence, RI 02912, USA.
Present address: Pace University, New York, NY 10038, USA.
These authors contributed equally to this work.
Although common among bacteria, lateral gene transfer—the movement of genes between distantly related organisms—is thought to occur only rarely between bacteria and multicellular eukaryotes. However, the presence of endosymbionts, such as Wolbachia pipientis, within some eukaryotic germlines may facilitate bacterial gene transfers to eukaryotic host genomes. We therefore examined host genomes for evidence of gene transfer events from Wolbachia bacteria to their hosts. We found and confirmed transfers into the genomes of 4 insect and 4 nematode species that range from nearly the entire Wolbachia genome (>1 megabase) to short (<500 base pairs) insertions. Potential Wolbachia to host transfers were also detected computationally in three additional sequenced insect genomes. We also show that some of these inserted Wolbachia genes are transcribed within eukaryotic cells lacking endosymbionts. Therefore, heritable lateral gene transfer occurs into eukaryotic hosts from their prokaryote symbionts, potentially providing a mechanism for acquisition of new genes and functions.
