一項(xiàng)研究說,，科學(xué)家發(fā)現(xiàn)了一種感染鞭毛蟲 Cafeteria roenbergensis 的巨大海洋病毒。Cafeteria roenbergensis 是一種廣泛分布的浮游生物捕食者，在海洋食物網(wǎng)中占據(jù)著一個(gè)關(guān)鍵的位置。
自從發(fā)現(xiàn)多噬棘阿米巴模仿病毒（Acanthamoeba polyphaga mimivirus）以來，所謂的巨病毒一直讓進(jìn)化生物學(xué)家感到迷惑,。多噬棘阿米巴模仿病毒感染淡水阿米巴，擁有120萬個(gè)堿基對的基因組,，比一些細(xì)胞生物的基因組還大,。
Curtis A. Suttle及其同事分析了一種感染 Cafeteria roenbergensis 的未知病毒，它在90年代早期它在德克薩斯的沿海水中曾被分離出來,。這組作者說,，這種病原體的基因組含有大約73萬個(gè)堿基對，這可能讓它成為已知最大的海洋病毒,。這種被命名為 CroV 的病毒擁有大量基因,，這些基因通常被活細(xì)胞用于修復(fù)它們的DNA損傷以及合成蛋白質(zhì)和糖。CroV 還擁有編碼病毒復(fù)制需要但是必須從宿主生物那里獲取的一些蛋白質(zhì)的基因。由于病毒無法獨(dú)立復(fù)制,，它們被歸類為“非生命”,。但是像 CroV 這樣的擁有復(fù)制機(jī)能的功能組件的巨病毒挑戰(zhàn)了這一分類。這組作者報(bào)告說,，CroV 可能還代表了一大組大多未知但是具有生態(tài)重要性的海洋巨病毒,。（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.
