據(jù)物理學(xué)家組織網(wǎng)報(bào)道，英屬哥倫比亞大學(xué)(UBC)已經(jīng)發(fā)現(xiàn)世界上最大、最復(fù)雜的海洋病毒,，Cafeteria roenbergensis病毒主要感染那些吃海洋生態(tài)系統(tǒng)中非常重要和分布廣泛的浮游生物的掠食者,。
這種病毒的基因組比一些細(xì)胞生物的基因組還大，它的遺傳復(fù)雜性使科學(xué)家感到疑惑,，不知道該把它歸為“無生命”生物,，還是“有生命”生物行列。海洋微生物學(xué)和環(huán)境病毒學(xué)專家,、這項(xiàng)研究的第一論文作者和英屬哥倫比亞大學(xué)教授柯蒂斯·蘇特勒說：“我們一般認(rèn)為病毒都很小,，是簡單生物體，只有少量基因,。然而我們在這種病毒里發(fā)現(xiàn)的大量遺傳機(jī)制,，只能在有生命的細(xì)胞生物體里找到，它們需要很多基因才能產(chǎn)生DNA,、RNA,、蛋白質(zhì)和糖。”
該研究成果發(fā)表在本周的《美國國家科學(xué)院院刊》上,。一般情況下,，病毒在活宿主細(xì)胞外無法自我復(fù)制，它們需要利用宿主提供的蛋白質(zhì)進(jìn)行復(fù)制,，自我復(fù)制形式是區(qū)分“無生命”和“有生命”生物的分界線,。然而最新發(fā)現(xiàn)的這種巨型病毒卻對上述歸類標(biāo)準(zhǔn)發(fā)起了挑戰(zhàn)，它們雖然仍需要一個(gè)細(xì)胞進(jìn)行復(fù)制,，但它們是在自己的基因組里進(jìn)行編碼的,。
20世紀(jì)90年代初，有人在德克薩斯州沿海水域發(fā)現(xiàn)這種巨型海洋病毒,。蘇特勒和他的科研組確定該病毒的基因組含有大約73萬個(gè)堿基對,。這使Cafeteria roenbergensis病毒成為目前已知的世界最大海洋病毒和第二大病毒，排名僅次于淡水病毒——多噬棘阿米巴模仿病毒,，后者擁有120萬個(gè)堿基對,。Cafeteria roenbergensis病毒還感染在海洋食物鏈中處于重要地位的浮游動(dòng)物。
蘇特勒說：“盡管這些海洋浮游生物的掠食行為在海洋和淡水系統(tǒng)的碳轉(zhuǎn)移及營養(yǎng)循環(huán)過程中起著重要作用,，但是我們對該病毒在這個(gè)系統(tǒng)里所扮演的角色幾乎一無所知,。毫無疑問，這種病毒可能還是一大組未知但是具有生態(tài)重要性的海洋巨型病毒的代表,。”（生物谷Bioon.com）
生物谷推薦英文摘要：
PNAS doi: 10.1073/pnas.1007615107
Giant virus with a remarkable complement of genes infects marine zooplankton
Matthias G. Fischera, Michael J. Allenb, William H. Wilsonc, and Curtis A. Suttlea,d,e,1
Departments of aMicrobiology and Immunology,
dBotany, and
eEarth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z4;
bPlymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom; and
cBigelow Laboratory for Ocean Sciences, West Boothbay Harbor, ME 04575-0475
As major consumers of heterotrophic bacteria and phytoplankton, microzooplankton are a critical link in aquatic foodwebs. Here, we show that a major marine microflagellate grazer is infected by a giant virus, Cafeteria roenbergensis virus (CroV), which has the largest genome of any described marine virus (≈730 kb of double-stranded DNA). The central 618-kb coding part of this AT-rich genome contains 544 predicted protein-coding genes; putative early and late promoter motifs have been detected and assigned to 191 and 72 of them, respectively, and at least 274 genes were expressed during infection. The diverse coding potential of CroV includes predicted translation factors, DNA repair enzymes such as DNA mismatch repair protein MutS and two photolyases, multiple ubiquitin pathway components, four intein elements, and 22 tRNAs. Many genes including isoleucyl-tRNA synthetase, eIF-2γ, and an Elp3-like histone acetyltransferase are usually not found in viruses. We also discovered a 38-kb genomic region of putative bacterial origin, which encodes several predicted carbohydrate metabolizing enzymes, including an entire pathway for the biosynthesis of 3-deoxy-d-manno-octulosonate, a key component of the outer membrane in Gram-negative bacteria. Phylogenetic analysis indicates that CroV is a nucleocytoplasmic large DNA virus, with Acanthamoeba polyphaga mimivirus as its closest relative, although less than one-third of the genes of CroV have homologs in Mimivirus. CroV is a highly complex marine virus and the only virus studied in genetic detail that infects one of the major groups of predators in the oceans.
