生物谷報(bào)道：無(wú)論是海洋,，湖泊，還是沼澤地,，只要有水的地方,，就有硅藻。硅藻是一種單細(xì)胞的藻類(lèi),，由幾個(gè)或很多個(gè)細(xì)胞可以聯(lián)結(jié)形成復(fù)雜有序的,、草樣的外殼。令人奇怪的是,，這些極其微小的浮游植物,，卻可能是下一代計(jì)算機(jī)芯片重大突破的關(guān)鍵。
硅藻堅(jiān)硬的細(xì)胞壁由排成線(xiàn)狀的硅質(zhì)組成,，硅質(zhì)與半導(dǎo)體工業(yè)最關(guān)鍵的材料硅有關(guān),。威斯康星大學(xué)麥迪遜分校（University of Wisconsin-Madison）的生化教授、UW-Madison生物技術(shù)中心的主任Michael Sussman說(shuō),，如果我們能夠在遺傳上控制硅藻細(xì)胞壁生成的過(guò)程,，我們就發(fā)明了一種新的納米制造方法，使我們能用硅藻制造芯片,。
為了實(shí)現(xiàn)這個(gè)目的,，Sussman和華盛頓大學(xué)的硅藻專(zhuān)家Virginia Armbrust領(lǐng)導(dǎo)的一個(gè)小組對(duì)硅藻進(jìn)行研究，結(jié)果在海鏈藻（Thalassiosira pseudonan）中發(fā)現(xiàn)涉及硅質(zhì)生物合成的75個(gè)基因,。研究結(jié)果發(fā)表在1月21日在線(xiàn)版的PNAS上,。硅藻的基因組序列在2004年就由Armbrust教授主導(dǎo)完成。Armbrust是海洋學(xué)教授,，主要研究硅藻的生態(tài)學(xué),。
硅藻的基因組序列使得Sussan教授可以開(kāi)始操縱與硅質(zhì)生成有關(guān)的基因,，有可能利用它們來(lái)生產(chǎn)計(jì)算機(jī)芯片的超精細(xì)線(xiàn)。Sussman表示,，這將極大提高芯片的速度,，因?yàn)楣柙迳a(chǎn)出的超精細(xì)線(xiàn)，遠(yuǎn)遠(yuǎn)小于現(xiàn)今技術(shù)所能達(dá)到的極限,。
Sussman表示,，每隔幾年，半導(dǎo)體工業(yè)就能夠?qū)⒂?jì)算機(jī)晶體管的密度增加一半,。在過(guò)去的30年通過(guò)光刻法實(shí)現(xiàn)這種飛速發(fā)展,，但現(xiàn)在卻遇到了瓶頸，因?yàn)槿藗円堰_(dá)到可見(jiàn)光的分辨極限,。
Armbrust’實(shí)驗(yàn)室的博士后,、該論文的第一作者Thomas Mock表示，在硅藻超凡的工程技術(shù)被發(fā)現(xiàn)之前,，生態(tài)學(xué)家感興趣的,，主要是硅藻在地球碳循環(huán)中的作用。這些光合作用細(xì)胞吸收二氧化碳并沉入海底,。每年從環(huán)境中移除的二氧化碳,，有超過(guò)20%是被硅藻吸收的，這個(gè)數(shù)字與地球上所有的熱帶雨林吸收的二氧化碳相當(dāng),。
但研究這些水藻發(fā)現(xiàn)了其它迷人的前景,。大約100,000種硅藻，每一種都有結(jié)構(gòu)獨(dú)特的細(xì)胞壁,。在研究硅藻的過(guò)程中,，這一點(diǎn)讓Sussman著迷不已,。
為了確定與這些獨(dú)特的細(xì)胞壁有關(guān)的基因,，研究人員使用了由Sussman、UW-Madison電氣工程師Franco Cerrina和遺傳學(xué)家Fred Blattner設(shè)計(jì)制造的DNA芯片,。上述三人聯(lián)合創(chuàng)建了一家生物技術(shù)公司NimbleGen,。簡(jiǎn)單地說(shuō)，DNA芯片能夠讓科學(xué)家找出一個(gè)特定的細(xì)胞反應(yīng)過(guò)程,，涉及到哪些基因,。在這個(gè)例子中，硅藻在低濃度的硅酸（合成硅質(zhì)的原料）環(huán)境生長(zhǎng),，DNA芯片用來(lái)鑒定那些基因起了作用,。
在硅酸缺乏時(shí)，表達(dá)量增高最多的30個(gè)基因中,，有25個(gè)完全是新的,，與已知的基因沒(méi)有任何相似性。
Sussman說(shuō)，現(xiàn)在我們知道了這個(gè)單細(xì)胞浮游植物的13,000個(gè)基因中,，哪一些與硅質(zhì)的生物合成過(guò)程有關(guān),。我們可以從零開(kāi)始研究這30個(gè)基因，并以基因工程的方法操縱這些基因的表達(dá),，看看結(jié)果如何,。
Sussman非常有信心，他表示,，長(zhǎng)遠(yuǎn)來(lái)看,，這些發(fā)現(xiàn)能夠幫助他進(jìn)一步改進(jìn)這個(gè)研究中所用的DNA芯片。這就像獅子王在唱主題曲“生生不息”,。
生物谷推薦原始出處：
Published online before print January 22, 2008
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0707946105
ENVIRONMENTAL SCIENCES
Whole-genome expression profiling of the marine diatom Thalassiosira pseudonana identifies genes involved in silicon bioprocesses
Thomas Mock*, Manoj Pratim Samanta, Vaughn Iverson*, Chris Berthiaume*, Matthew Robison, Karie Holtermann*, Colleen Durkin*, Sandra Splinter BonDurant, Kathryn Richmond, Matthew Rodesch, Toivo Kallas, Edward L. Huttlin¶, Francesco Cerrina,||, Michael R. Sussman,¶,**, and E. Virginia Armbrust*,**
*School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195; Systemix Institute, Los Altos, CA 94024; Biotechnology Center, University of Wisconsin, Madison, WI 53706; Department of Biology and Microbiology, University of Wisconsin, Oshkosh, WI 54901; and Departments of ¶Biochemistry and ||Electrical and Computer Engineering, University of Wisconsin, Madison, WI 53706
Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved December 3, 2007 (received for review August 22, 2007)
Abstract
Formation of complex inorganic structures is widespread in nature. Diatoms create intricately patterned cell walls of inorganic silicon that are a biomimetic model for design and generation of three-dimensional silica nanostructures. To date, only relatively simple silica structures can be generated in vitro through manipulation of known diatom phosphoproteins (silaffins) and long-chain polyamines. Here, we report the use of genome-wide transcriptome analyses of the marine diatom Thalassiosira pseudonana to identify additional candidate gene products involved in the biological manipulation of silicon. Whole-genome oligonucleotide tiling arrays and tandem mass spectrometry identified transcripts for >8,000 genes, 3,000 of which were not previously described and included noncoding and antisense RNAs. Gene-specific expression profiles detected a set of 75 genes induced only under low concentrations of silicon but not under low concentrations of nitrogen or iron, alkaline pH, or low temperatures. Most of these induced gene products were predicted to contain secretory signals and/or transmembrane domains but displayed no homology to known proteins. Over half of these genes were newly discovered, identified only through the use of tiling arrays. Unexpectedly, a common set of 84 genes were induced by both silicon and iron limitations, suggesting that biological manipulation of silicon may share pathways in common with iron or, alternatively, that iron may serve as a required cofactor for silicon processes. These results provide insights into the transcriptional and translational basis for the biological generation of elaborate silicon nanostructures by these ecologically important microbes.
silica | transcriptome | iron | nitrogen | temperature
