近日,，美國斯坦福大學(xué)霍華德休斯醫(yī)學(xué)研究所，著名華人神經(jīng)生物學(xué)家駱利群博士課題小組的李凌博士及同事開發(fā)了一項(xiàng)能夠在成體水平小鼠腦區(qū)的復(fù)雜神經(jīng)網(wǎng)絡(luò)系統(tǒng)中特異性標(biāo)記單個神經(jīng)元細(xì)胞及其神經(jīng)突觸分布形式的技術(shù),。
該項(xiàng)技術(shù)利用轉(zhuǎn)基因方法在小鼠不同腦區(qū)的神經(jīng)元細(xì)胞可控地表達(dá)不同的熒光蛋白和Synaptophysin (突觸囊泡蛋白)，應(yīng)用不同分子標(biāo)記對神經(jīng)元細(xì)胞及其突觸進(jìn)行特異性標(biāo)記,，能夠在單個神經(jīng)元細(xì)胞水平上提供詳盡的三維神經(jīng)突觸分布信息,，從而了解單個神經(jīng)元細(xì)胞在復(fù)雜腦區(qū)回路的連接機(jī)制，對于破譯大腦復(fù)雜神經(jīng)回路提供了方法學(xué)上的可能,。該項(xiàng)成果已經(jīng)發(fā)表在近日的PLoS ONE雜志上,。
三維神經(jīng)細(xì)胞體內(nèi)照片(此照片由斯坦福大學(xué)駱利群教授提供）3D圖像下載地址
現(xiàn)代神經(jīng)生物學(xué)的一個重要課題就是怎樣破解哺乳動物甚至人類的高度復(fù)雜化的神經(jīng)網(wǎng)絡(luò) ---大腦。神經(jīng)系統(tǒng)中神經(jīng)元細(xì)胞功能和結(jié)構(gòu)上的多樣性,，神經(jīng)回路的高度復(fù)雜性對這個當(dāng)代神經(jīng)生物學(xué)的關(guān)鍵性問題提出了極大的挑戰(zhàn),。此項(xiàng)全新的神經(jīng)元標(biāo)記方法無疑提供了有力工具。此項(xiàng)技術(shù)可以顯示轉(zhuǎn)基因小鼠大腦的不同區(qū)域在不同發(fā)育階段的各種特異性神經(jīng)元及其突觸分布形式,，這將使神經(jīng)生物學(xué)家能夠了解大腦神經(jīng)網(wǎng)絡(luò)發(fā)育的詳盡信息,，有助于對大腦工作方式進(jìn)行深入研究。能夠直接地、實(shí)時地觀測到活體實(shí)驗(yàn)小鼠大腦中未分化的細(xì)胞一步步發(fā)育為單個的復(fù)雜神經(jīng)細(xì)胞,，然后形成復(fù)雜的神經(jīng)網(wǎng)絡(luò),，這對于未來的神經(jīng)回路研究領(lǐng)域意義重大。該技術(shù)不僅能推動在正?；虿B(tài)腦中的測繪工作,，而且還可以推廣用到其他復(fù)雜細(xì)胞群中，例如免疫系統(tǒng)或者造血干細(xì)胞系統(tǒng)等等,。
李凌博士曾經(jīng)就職于麻省理工學(xué)院（MIT）著名的懷特海（Whitehead）研究所,，在美國著名科學(xué)院院士Harvey Lodish的實(shí)驗(yàn)室工作期間發(fā)表于《科學(xué)》（Science）雜志的學(xué)術(shù)論文，揭示了microRNA功能,，被評選為2004年十大科學(xué)研究突破之一。 2005年李凌博士加入斯坦福大學(xué)駱利群實(shí)驗(yàn)室,，開始了對哺乳動物神經(jīng)回路發(fā)育的研究,。在此期間，李凌及其同事發(fā)現(xiàn),目前的神經(jīng)網(wǎng)絡(luò)研究極大地受限于神經(jīng)細(xì)胞標(biāo)識技術(shù),，因此致力于開發(fā)單個神經(jīng)元細(xì)胞的標(biāo)記方法,。李凌博士及其同事已經(jīng)利用該技術(shù)對小鼠小腦進(jìn)行了初步研究，結(jié)果顯示小鼠小腦中的顆粒細(xì)胞（granule cell）的神經(jīng)突觸密度比人們以前的估計(jì)高出一倍,，這意味著小鼠小腦中的神經(jīng)網(wǎng)絡(luò)比以前的估計(jì)還要復(fù)雜,。目前，世界最著名的生物制藥公司之一基因泰克（Genentech）已經(jīng)向斯坦福大學(xué)購買了此項(xiàng)專利,，并已開始將其用于對人類神經(jīng)系統(tǒng)疾病及相關(guān)藥物的研究和開發(fā),。(生物谷Bioon.net)
生物谷推薦原文出處：
PLoS ONE 5(7): e11503. doi:10.1371/journal.pone.0011503
Visualizing the Distribution of Synapses from Individual Neurons in the Mouse Brain
Ling Li1, Bosiljka Tasic1, Kristina D. Micheva2, Vsevolod M. Ivanov 1,3, Maria L. Spletter1, Stephen J. Smith2, Liqun Luo1*
1 Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, California, United States of America, 2 Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America, 3 Lynbrook High School, San Jose, California, United States of America
Background
Proper function of the mammalian brain relies on the establishment of highly specific synaptic connections among billions of neurons. To understand how complex neural circuits function, it is crucial to precisely describe neuronal connectivity and the distributions of synapses to and from individual neurons.
Methods and Findings
In this study, we present a new genetic synaptic labeling method that relies on expression of a presynaptic marker, synaptophysin-GFP (Syp-GFP) in individual neurons in vivo. We assess the reliability of this method and use it to analyze the spatial patterning of synapses in developing and mature cerebellar granule cells (GCs). In immature GCs, Syp-GFP is distributed in both axonal and dendritic regions. Upon maturation, it becomes strongly enriched in axons. In mature GCs, we analyzed synapses along their ascending segments and parallel fibers. We observe no differences in presynaptic distribution between GCs born at different developmental time points and thus having varied depths of projections in the molecular layer. We found that the mean densities of synapses along the parallel fiber and the ascending segment above the Purkinje cell (PC) layer are statistically indistinguishable, and higher than previous estimates. Interestingly, presynaptic terminals were also found in the ascending segments of GCs below and within the PC layer, with the mean densities two-fold lower than that above the PC layer. The difference in the density of synapses in these parts of the ascending segment likely reflects the regional differences in postsynaptic target cells of GCs.
Conclusions
The ability to visualize synapses of single neurons in vivo is valuable for studying synaptogenesis and synaptic plasticity within individual neurons as well as information flow in neural circuits.
