科學(xué)家們創(chuàng)造了完全受他們控制的蠕蟲(chóng)“小機(jī)器人”,。
他們使用的是激光點(diǎn),。他們可以用它來(lái)讓蠕蟲(chóng)左轉(zhuǎn),、停止或是產(chǎn)卵,。研究人員將他們的研究成果發(fā)表在1月16日的《自然—方法學(xué)》網(wǎng)絡(luò)版上,。
研究人員用激光系統(tǒng)(左)刺激線蟲(chóng)的神經(jīng)細(xì)胞來(lái)操控其行為
不過(guò),，這個(gè)叫做CoLBeRT(實(shí)時(shí)移動(dòng)與行為控制)的系統(tǒng)并不只是創(chuàng)造一個(gè)沒(méi)有思維的僵尸蠕蟲(chóng)。它讓科學(xué)家們能夠逐個(gè)細(xì)胞地分解復(fù)雜的行為,。
未參與該研究的多倫多大學(xué)生物學(xué)家威廉·劉說(shuō)：“這個(gè)系統(tǒng)確實(shí)很不同尋常,。它在理解行為方面取得了重要的進(jìn)展。”
透明而微小的線蟲(chóng)特別容易受到用光線進(jìn)行的意識(shí)控制,。這種蟲(chóng)子還有一個(gè)好處,，那就是研究人員知道其所有302個(gè)神經(jīng)細(xì)胞的準(zhǔn)確位置。但在此之前,，沒(méi)有什么好的辦法來(lái)對(duì)每個(gè)細(xì)胞進(jìn)行研究,，尤其是對(duì)一個(gè)蠕動(dòng)的動(dòng)物體內(nèi)的細(xì)胞。
該研究的共同作者,、哈佛大學(xué)的安德魯·萊費(fèi)爾說(shuō)：“這個(gè)工具讓我們能夠進(jìn)入其內(nèi)部,，在動(dòng)物移動(dòng)的過(guò)程中撥弄和刺激其神經(jīng)細(xì)胞。”
該系統(tǒng)基于新興的光遺傳學(xué)領(lǐng)域,，在該領(lǐng)域中,，光被用來(lái)開(kāi)啟或關(guān)閉細(xì)胞。萊費(fèi)爾和他的同事將光敏分子植入蠕蟲(chóng)體內(nèi)特定的細(xì)胞群中,。
隨后,，該研究小組開(kāi)發(fā)的一個(gè)計(jì)算機(jī)程序在顯微鏡中定位目標(biāo)細(xì)胞。一旦找到該細(xì)胞,，程序就引導(dǎo)激光,，讓一小束光擊中細(xì)胞。
萊費(fèi)爾說(shuō)：“我們用光照射神經(jīng)細(xì)胞的時(shí)候,，我們只對(duì)那一個(gè)神經(jīng)細(xì)胞進(jìn)行撞擊,，不碰到其他任何東西。”
找到細(xì)胞并用光撞擊目標(biāo)的整個(gè)過(guò)程約需要20毫秒,。隨著蠕蟲(chóng)位置的改變,，其信息反饋給計(jì)算機(jī)程序，激光會(huì)進(jìn)行調(diào)整,。如果蠕蟲(chóng)爬得太遠(yuǎn),，裝有馬達(dá)的顯微鏡載臺(tái)會(huì)將它拉回來(lái)。
威廉·劉說(shuō),，這種新方法最大的一個(gè)好處就是它能用于移動(dòng)的動(dòng)物,。“這些蟲(chóng)子不是用什么東西固定起來(lái)的———它們自由移動(dòng),。能讓你看到這種真正不受約束的有機(jī)體的系統(tǒng)并不多。”
由位于亞特蘭大的佐治亞技術(shù)學(xué)院的杰弗里·斯特曼領(lǐng)導(dǎo)的另一組科學(xué)家則宣布了一項(xiàng)類(lèi)似的對(duì)蠕蟲(chóng)進(jìn)行意識(shí)控制的技術(shù),，同樣發(fā)表在1月16日的《自然—方法學(xué)》網(wǎng)絡(luò)版上,。
威廉·劉說(shuō)，兩種方法是類(lèi)似的,， CoLBeRT法似乎更快一些,，但如果蠕蟲(chóng)爬行緩慢，那么斯特曼小組使用的辦法可能在激光瞄準(zhǔn)方面更加精確,。“兩篇論文對(duì)于從整體上理解行為是否都有幫助,？的確如此。”（生物谷Bioon.com）
生物谷推薦原文出處：
Nature Methods doi:10.1038/nmeth.1554
Optogenetic manipulation of neural activity in freely moving Caenorhabditis elegans
Andrew M Leifer,Christopher Fang-Yen,Marc Gershow,Mark J Alkema& Aravinthan D T Samuel
We present an optogenetic illumination system capable of real-time light delivery with high spatial resolution to specified targets in freely moving Caenorhabditis elegans. A tracking microscope records the motion of an unrestrained worm expressing channelrhodopsin-2 or halorhodopsin in specific cell types. Image processing software analyzes the worm's position in each video frame, rapidly estimates the locations of targeted cells and instructs a digital micromirror device to illuminate targeted cells with laser light of the appropriate wavelengths to stimulate or inhibit activity. Because each cell in an unrestrained worm is a rapidly moving target, our system operates at high speed (~50 frames per second) to provide high spatial resolution (~30 μm). To test the accuracy, flexibility and utility of our system, we performed optogenetic analyses of the worm motor circuit, egg-laying circuit and mechanosensory circuits that have not been possible with previous methods.
Nature Methods doi:10.1038/nmeth.1555
Real-time multimodal optical control of neurons and muscles in freely behaving Caenorhabditis elegans
Jeffrey N Stirman,Matthew M Crane,Steven J Husson,Sebastian Wabnig,Christian Schultheis,Alexander Gottschalk& Hang Lu
The ability to optically excite or silence specific cells using optogenetics has become a powerful tool to interrogate the nervous system. Optogenetic experiments in small organisms have mostly been performed using whole-field illumination and genetic targeting, but these strategies do not always provide adequate cellular specificity. Targeted illumination can be a valuable alternative but it has only been shown in motionless animals without the ability to observe behavior output. We present a real-time, multimodal illumination technology that allows both tracking and recording the behavior of freely moving C. elegans while stimulating specific cells that express channelrhodopsin-2 or MAC. We used this system to optically manipulate nodes in the C. elegans touch circuit and study the roles of sensory and command neurons and the ultimate behavioral output. This technology enhances our ability to control, alter, observe and investigate how neurons, muscles and circuits ultimately produce behavior in animals using optogenetics.
