生物谷綜合：美國科學家最近測定了地球上最古老的物種之一——海葵的基因組。他們發(fā)現(xiàn)，該基因組的復雜程度超乎想象,，且與包括人類在內(nèi)的脊椎動物有很大的相似性，這一成果有望革新人們對物種進化的認識,。相關(guān)論文發(fā)表在7月6日的《科學》雜志上,。
領(lǐng)導該研究的美國能源部聯(lián)合基因組研究所（Department of Energy Joint Genome Institute）Nicholas H. Putnam和其他科學家一道，測定了一種名為Nematostella vectensis的星狀?？幕蚪M,。研究人員發(fā)現(xiàn)，?？幕蚪M包括4.5億個堿基對和18000個編碼蛋白基因,。
通過對比海葵與其他已知物種的基因組序列,，研究人員推測并重建了新元古代后生動物（eumetazoan）的基因組特征,，而新元古代后生動物被認為是除海綿外的其他多細胞生物的祖先。他們發(fā)現(xiàn),，新元古代后生動物全基因組中的80%明顯是真菌,、植物和其他真核生物的同源基因,，其余的20%是新元古代后生動物所特有的，它們負責信號轉(zhuǎn)換,、細胞通訊,、胚胎發(fā)生以及神經(jīng)和肌肉的功能。論文高級作者,、加州大學伯克利分校的Daniel S. Rokhsar表示,，“現(xiàn)在，我們擁有了整個動物王國的基礎(chǔ)‘工具箱’,，它賦予所有的動物一種統(tǒng)一性,。”
進一步的研究表明,，人類與?？痊F(xiàn)代動物有三分之二的基因家族源自于它們的新元古代后生動物祖先。相比之下,，果蠅與線蟲的繼承性只有大約二分之一,。同時，研究人員發(fā)現(xiàn),，人類和?？幕騼?nèi)含子與外顯子（exon-intron）結(jié)構(gòu)也十分相似，基因組中內(nèi)含子較多,。而果蠅與線蟲丟失了新元古代后生祖先大約50%到90%的內(nèi)含子,。這些發(fā)現(xiàn)意味著果蠅和蠕蟲基因組在進化過程中喪失了一定的復雜性。因此,，新的研究挑戰(zhàn)了一個人們廣泛接受的觀點：生物會越進化越復雜,。
除此之外，科學家還在?？腿祟惢蚪M中發(fā)現(xiàn)了大量的關(guān)聯(lián)基因塊（blocks of linked genes）,，它們也都源于新元古代后生動物。
美國國家生物技術(shù)信息中心（National Center for Biotechnology Information）的Eugene V. Koonin表示,，“?？@樣的原始的動物的基因組如此復雜，實在讓人驚訝,。這一發(fā)現(xiàn)說明,，盡管現(xiàn)代動物的祖先在形態(tài)學上或許比較簡單，但在基因組結(jié)構(gòu)和調(diào)控機制上已經(jīng)十分復雜,。”（科學網(wǎng)）
原始出處:
Science 6 July 2007:
Vol. 317. no. 5834, pp. 86 - 94
DOI: 10.1126/science.1139158
Research Articles
Sea Anemone Genome Reveals Ancestral Eumetazoan Gene Repertoire and Genomic Organization
Nicholas H. Putnam,1 Mansi Srivastava,2 Uffe Hellsten,1 Bill Dirks,2 Jarrod Chapman,1 Asaf Salamov,1 Astrid Terry,1 Harris Shapiro,1 Erika Lindquist,1 Vladimir V. Kapitonov,3 Jerzy Jurka,3 Grigory Genikhovich,4 Igor V. Grigoriev,1 Susan M. Lucas,1 Robert E. Steele,5 John R. Finnerty,6 Ulrich Technau,4 Mark Q. Martindale,7 Daniel S. Rokhsar1,2*
Sea anemones are seemingly primitive animals that, along with corals, jellyfish, and hydras, constitute the oldest eumetazoan phylum, the Cnidaria. Here, we report a comparative analysis of the draft genome of an emerging cnidarian model, the starlet sea anemone Nematostella vectensis. The sea anemone genome is complex, with a gene repertoire, exon-intron structure, and large-scale gene linkage more similar to vertebrates than to flies or nematodes, implying that the genome of the eumetazoan ancestor was similarly complex. Nearly one-fifth of the inferred genes of the ancestor are eumetazoan novelties, which are enriched for animal functions like cell signaling, adhesion, and synaptic transmission. Analysis of diverse pathways suggests that these gene "inventions" along the lineage leading to animals were likely already well integrated with preexisting eukaryotic genes in the eumetazoan progenitor.
1 Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA.
2 Center for Integrative Genomics and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
3 Genetic Information Research Institute, 1925 Landings Drive, Mountain View, CA 94043, USA.
4 Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008, Bergen, Norway.
5 Department of Biological Chemistry and the Developmental Biology Center, University of California, Irvine, CA 92697, USA.
6 Department of Biology, Boston University, Boston, MA 02215, USA.
7 Kewalo Marine Laboratory, University of Hawaii, Honolulu, HI 96813, USA.
* To whom correspondence should be addressed. E-mail: [email protected]
