我们要感谢岳（保罗）胡锦涛，雷切尔SINIT为他们提供技术援助。这项研究是由美国国立卫生研究院资助（PN2 EY016525），并从唐氏综合症的研究与治疗基金会和拉里·L.希尔布鲁姆基金会的资助支持。

手术和动物的程序进行了严格按照美国国立卫生研究院指南的护理和使用实验动物。所有涉及使用动物实验是由加州大学圣地亚哥分校机构动物照顾及使用委员会批准。 1质粒的克隆，单生物素BDNF的表达和纯化（mBtBDNF） 注:建设前期proBDNFavi和BirA的cDNA插入在HEK293FT细胞10 pcDNA3.1载体和共表达。使用Ni-NTA珠根据生产成熟的和生物活性monobiotinylated神经生长因子（mBtNGF）10的先前公布的方法mBtBDNF纯化。 2，制备微流控商会微流体神经元培养装置，能够使流体流动的隔离神经元胞体的轴突。每个解剖前集会权与新涂盖玻片室。用于微流控室在这个协议是商业购买（见材料和​​设备的表）。手洗和重复购买商业腔高达5-6x。 <ol><li>手洗的1％Alconox清洁剂的微流控室。漂洗三次，用Milli-Q水用于各30分钟。再次手洗室70％的乙醇。 </li><li>铺陈室晾干的封口膜的层流罩。辐射灭菌的腔两侧紫外光下20分钟。存放在无菌15cm培养皿在室温下用石蜡膜密封消毒室。 </li><li>将24×40mm的1号盖玻片在玻璃容器中。浸泡过夜旋转器上在35％盐酸盖玻片。在第二天，冲洗盖玻片三次，每次加水30分钟。 </li><li>浸渍每个盖玻片到100％的乙醇和燃烧过本生灯消毒盖玻片一个接一个。储存干盖玻片在无菌培养皿中，并保持在室温下直至涂层。 </li><li>莱OU吨，15厘米的培养皿中的盖玻片。外套每个盖玻片用0.7ml的0.01％的聚-L-赖氨酸（PLL），并培育在通风橱中在室温下进行。 </li><li> 1小时后，冲洗盖玻片三次，用无菌水。干盖玻片真空和地方每个盖玻片成一块2.4英寸的培养皿。 </li><li>组装微流体室中，放置与微沟槽侧的腔室的底部上的PLL涂覆的盖玻片小心不要接触到微槽。轻轻按下室用枪头，以确保室内进行密封。 </li></ol> 3，神经解剖文化和板块上庭<ol><li>放置两个E17-E18大鼠海马（一个脑）解剖在15ml锥形管中含2ml夹层缓冲液（HBSS，无钙无镁，用1％青霉素/链霉素和10mM HEPES。冲洗组织3倍用5ml每次清扫缓冲拆下清扫缓冲尽可能并添加900微升新鲜二ssection缓冲区。 </li><li>消化组织，加入100μl的10X胰蛋白酶（2.5％）进夹层缓冲，使1个工作浓度。放置锥形管在37℃水浴。消化后的10分钟，加入100μl的10毫克/毫升的DNase I至约1毫克/毫升的最终浓度。 </li><li>用火抛光的巴斯德玻璃吸管，轻轻地上下吹打5到10倍磨碎的组织。研磨后右，淬火用2ml平板培养基（神经基础有10％FBS，2mM的Glutamax的，2％B27）的胰蛋白酶。 </li><li>留在引擎盖样品5分钟，使组织中的任何碎片落户到了谷底。小心地取出2毫升上清液倒入干净无菌的15毫升锥形管中，离心分离机，在200×g离心5分钟以沉淀细胞。悬浮颗粒在50微升电镀媒体</li><li>计数细胞与血球。负载15-20微升细胞悬浮液（〜40,000个细胞）到微流体室中的一个隔室。放置室在培养箱中培养10分钟，以使细胞附着在盖玻片上。 10分钟后，加入更多的镀介质来填充该腔室的两个室。 </li><li>对解剖的第二天，完全（有2mM Glutamax的，2％B27的Neurobasal）在两个细胞体和轴突隔室更换电镀媒体与维护媒体。从海马神经元的轴突开始穿越微槽3天，达到5-7天之间的轴突舱。在这段时间内，用新鲜维持培养基，每24〜48小时，更换一半的培养介质。 </li></ol> QD-BDNF的4轴突运输<ol><li>之前住QD-BDNF的轴突运输的成像，从微流体室中的两个细胞体和轴突隔室耗尽BDNF通过彻底冲洗两个室用BDNF无，无血清的Neurobasal介质，每30分钟2小时。 </li><li>在BDNF的枯竭，准备QD-BDNF的结合物。搭配50纳米的单生物素化的BDNF二聚体用50nM的Neurobasal介质QD655-链霉抗生物共轭物和在冰上孵育60分钟。 </li><li>在轴突舱取出介质，加入300μlQD-BDNF 0.25纳米的终浓度为4小时，在37℃。为了尽量减少QD-BDNF的漫射到细胞体隔室，这是很重要的，以始终保持介质中的细胞体隔室更高的水平比在轴突隔室。前实时成像孵育后洗去未结合的QD-BDNF。 </li><li>使用倒置显微镜配有100X油物镜进行QD-BDNF运输的实时成像。预热的范围和附加到它的恒定温度（37℃）和CO 2（5％）的环境室中。使用一组德克萨斯红的激发/发射的多维数据集可视化的QD655信号。 </li><li>获取和捕捉中间的轴突内的延时图像1帧/秒的速度，总共2分钟使用CCD摄像头。使用细微沟槽，无轴突塔吨有没有量子点，因此没有信号的渗透控制。 </li><li>分析使用任何图像分析软件或NIH ImageJ的BDNF的运输。 </li></ol>

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没有利益冲突的声明。

在这项研究中，我们报道了一种新技术的发展，以产生具有生物活性，monobiotinylated BDNF（mBtBDNF），可以用来跟踪BDNF的轴突运输。通过缀合的蛋白质，以量子点的链霉亲和使用的微流体腔室，该方法允许一个检测BDNF在与单个分子的灵敏度，在实时的和具有空间分辨率和时间分辨率原代神经元的轴突运输。这里所使用的工具提供了由研究介导的BDNF / TrkB的信号内吞体的健康和疾病的神经元轴突运输?...

神经元是高度分化的细胞，其长，通常高度阐述的过程是基本建立和保持神经回路的结构和功能。轴突起着运载的货物和从突触至关重要的作用。蛋白质和细胞器的细胞胞体合成需要通过轴突运输到达突触前末梢，支持神经元功能。相应地，接收的信号在远端轴突需要被转并输送到体细胞。这些方法可用于神经元的存活，分化和维持所必需的。在某些神经元的轴突运输必须通过的距离超过1000倍的细胞体的直径进行，有可能容易地预想到，即使是很小的缺陷可显着影响神经元和电路功能。 脑源性神经营养因子（BDNF），生长因子的神经营养因子家族中的一员，是目前在马纽约州的大脑区域，包括海马，大脑皮层和基底前脑。 BDNF起着认知和记忆的形成所配套的存活，分化，并参与认知神经回路的功能至关重要的作用。 BDNF结合到其受体的酪氨酸激酶受体TrkB，在轴突终端那里它激活的TrkB介导的信号传导途径，包括有丝分裂原激活的蛋白激酶/细胞外信号调节蛋白激酶（MAPK / ERK），磷脂酰肌醇3激酶（PI3K）和磷脂酶C-γ（PLCγ）。在参与这些信号传导途径的蛋白被包装到内吞囊泡结构，以形成BDNF / TrkB的信令内体1-6被再逆行转运到神经元胞体。 微流体培养室是研究在正常条件下，以及在损伤和疾病7,8的设定轴突生物学一个非常有用的平台。通过隔离轴突从细胞体，该装置允许一个具体研究运输中的轴突8-10。在与在该研究中使用450微米的微沟槽屏障基于PDMS的微流体平台进行商业购买（参见材料表）。为了研究BDNF的运输，我们开发了一种新的技术，生产monobiotinylated BDNF（mBtBDNF）。我们把生物素受体肽，美联社（又称重组蛋白质）的优势。它是一个包含一个赖氨酸残基，可以由大肠杆菌酶的生物素连接酶，BirA的具体连接到生物素15的氨基酸序列。我们融合的重组蛋白质的小鼠预先proBDNF基因的C末端，通过PCR（ 图1A）。该构建体被克隆到哺乳动物表达载体pcDNA3.1 myc基因-His载体。我们还克隆的细菌BirA的DNA导入的pcDNA3.1 myc基因-His载体。两个质粒瞬时共转染到HEK293FT细胞表达两种蛋白。 BirA的催化毕结扎在具体的赖氨酸驻留在重组蛋白质中的BDNF的在1的C末端:1的比例以产生monobiotinylated BDNF单体。生物素化的，成熟的BDNF与〜18kDa的分子质量，回收和使用的Ni-树脂（ 图1C）的介质纯化。 BDNF的生物素化是完全的，作为判断无法通过免疫印迹法（ 图1D），以检测未修饰BDNF。链霉亲和共轭量子点，量子点655，分别用来标明mBtBDNF使QD-BDNF。的重组蛋白质的存在下不与BDNF的活性干扰作为mBtBDNF能够激活磷酸化的TrkB（ 图1E）和刺激神经 ​​突向外生长（ 图1F），以重组人BDNF（rhBDNF）的程度。免疫组化显示，QD-BDNF共定位与TrkB的海马神经轴突，表明QD-BDNF的生物活性（ 图1G）。研究了BDNF的运输，QD-BDNF加入到远端轴突隔室含E18大鼠海马神经元（ 图2A）微流控文化。在轴突QD-BDNF逆行运输被抓获的红色荧光标记（ 支持视频S1，S2）的实时现场图像。通过分析所产生的kymograph，QD-BDNF的观察可以在约1.06微米/秒（ 图3A）的移动速度逆向转移。 GFP或mCherry-标记的BDNF已被用于跟踪BDNF的神经轴突的运动。主要的缺点是，他们不是为单个分子的研究不够明亮。另外，无论是顺行性与逆行BDNF运动的存在使得难以评估的逆向转移BDNF是否是一种神经营养蛋白/受体复合体。 在这段视频中，我们展示了用于检查QD-BDNF在利用原代神经元的微流控室现场贩卖的技术。该ultrabrightness和量子点麦出色的耐光性ES能够进行BDNF传输的长期跟踪。这些技术可被利用来提高AD中，HD和其他神经变性疾病的轴突功能的研究。

<table border="0" cellpadding="0" cellspacing="0" width="641">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:261px;">Name</td>
			<td style="width:205px;">Company</td>
			<td style="width:175px;">Catalog Number</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Platinum pfx DNA polymerase&#160;</td>
			<td>Invitrogen</td>
			<td>11708021</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EcoRI&#160;</td>
			<td>Fermentas</td>
			<td>FD0274</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">BamHI&#160;</td>
			<td>Fermentas</td>
			<td>FD0054</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HEK293FT cells</td>
			<td>Invitrogen</td>
			<td>R70007</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DMEM-high glucose media</td>
			<td>Mediatech</td>
			<td>10-013-CV</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">d-biotin&#160;</td>
			<td>Sigma</td>
			<td>B4639</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TurboFect&#160;</td>
			<td>Fermentas</td>
			<td>R0531</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PMSF&#160;&#160;</td>
			<td>Sigma</td>
			<td>P7626</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">aprotinin</td>
			<td>Sigma</td>
			<td>A6279</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ni-NTA resins</td>
			<td>Qiagen</td>
			<td>30250</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">protease inhibitors cocktail</td>
			<td>Sigma</td>
			<td>&#160;S8820</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">silver staining kit&#160;</td>
			<td>G-Biosciences</td>
			<td>786-30</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">human recombinant BDNF</td>
			<td>Genentech</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microfluidic chambers</td>
			<td>Xona</td>
			<td>SND450</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">24x40 mm No. 1 glass coverslips&#160;</td>
			<td>VWR</td>
			<td>48393-060</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">poly-L-Lysine&#160;</td>
			<td>Cultrex</td>
			<td>3438-100-01</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HBSS</td>
			<td>Gibco</td>
			<td>14185-052</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DNase I</td>
			<td>Roche</td>
			<td>10104159001</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trypsin</td>
			<td>Gibco</td>
			<td>15090-046</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Neurobasal&#160;</td>
			<td>Gibco</td>
			<td>21103-049</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">FBS&#160;</td>
			<td>Invitrogen</td>
			<td>16000-044</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">GlutaMax&#160;</td>
			<td>Invitrogen</td>
			<td>35050-061</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">B27&#160;&#160;</td>
			<td>Gibco</td>
			<td>17504-044</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">QD655-streptavidin conjugates</td>
			<td>Invitrogen</td>
			<td>&#160;Q10121MP</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">anti-Avi tag antibody</td>
			<td>GenScript</td>
			<td>A00674</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">streptavidin-agarose beads&#160;</td>
			<td>Life Technology</td>
			<td>&#160;SA100-04</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">trichloroacetic acid</td>
			<td>Sigma</td>
			<td>T6399</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HRP-streptavidin&#160;</td>
			<td>Thermo Scientific</td>
			<td>N100</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">anti-pTrkB antibody</td>
			<td colspan="2">a generous gift from Dr M. Chao of NYU</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">anti-TrkB antibody</td>
			<td>BD Science</td>
			<td>610101</td>
		</tr>
	</tbody>
</table>

real-time imaging of axonal transport of quantum dot-labeled bdnf in primary neurons

BDNF在神经元存活，分化和功能的若干方面具有重要作用。结构和功能的缺陷在轴突日益被看作神经变性疾病，包括阿尔茨海默氏病（AD）和亨廷顿病（HD）的早期特征。尚不清楚是由轴索损伤诱导机制（S）。我们报道了一种新技术的发展，以产生具有生物活性，monobiotinylated BDNF（mBtBDNF），可以用来跟踪BDNF的轴突运输。量子点标记的BDNF（QD-BDNF）是由共轭量子点655到mBtBDNF制备。一种微流体装置被用于分离从神经元胞体的轴突。除了QD-BDNF的到轴突舱允许的BDNF运输轴突的实时成像。我们证明了QD-BDNF的移动基本上是完全逆行，除了极少数停顿，约为1.06微米/秒的移动速度。此系统可用于研究我的破坏轴突功能在AD或HD，以及其他退行性疾病chanisms。

生产具有生物活性的单 - 生物素化的BDNF的纯化 BDNF的稠合有一个重组蛋白质序列（GGGLNDIFEAQKIEWHE）的表达载体，根据以前发表的协议10创建。全长融合蛋白的分子质量预测为〜32kDa的（ <a href="http://ca.expasy.org/tools/pi_tool.html" target="_blank">http://ca.expasy.org/tools/pi_tool.html</a> ）Monobiotinylated成熟的BDNF为18 kDa的（ 图1A）的预测分子量制作在HEK293FT细胞和纯化的条件培?...

Watch this Scientific Journal Video about Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons at JoVE.com

Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons

BDNF，神经营养因子，对轴突运输是几个神经元群体的生存和功能是至关重要的。一些退行性疾病的标志是轴索结构和功能的破坏。我们展示了用于检查QD-BDNF在使用初级神经元微流控室现场贩卖的技术。

初级量子神经元轴突运输的实时成像点标记的BDNF

BDNF plays an important role in several facets of neuronal survival, differentiation, and function. Structural and functional deficits in axons are ...

real-time-imaging-axonal-transport-quantum-dot-labeled-bdnf-primary

Research

JoVE Journal

Neuroscience

15.0K 次观看.  University of California, San Diego.  BDNF，神经营养因子，对轴突运输是几个神经元群体的生存和功能是至关重要的。一些退行性疾病的标志是轴索结构和功能的破坏。我们展示了用于检查QD-BDNF在使用初级神经元微流控室现场贩卖的技术。 

视频: Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons

Organotypic Slice Culture of GFP-expressing Mouse Embryos for Real-time Imaging of Peripheral Nerve Outgrowth

For many purposes, the cultivation of mouse embryos ex vivo as organotypic slices is desirable. For example, we employ a transgenic mouse line (tauGFP) in which the enhanced version of the green fluorescent protein (EGFP) is exclusively expressed in all neurons of the developing central and peripheral nervous system1, allowing the possibility to both film the innervation of the forelimb and to manipulate this process with pharmacological and genetic techniques2. The most critical parameter in the successful cultivation of such slice cultures is the method by which the slices are prepared. After extensive testing of a variety of methods, we have found that a vibratome is the best possible device to slice the embryos such that they routinely result in a culture that demonstrates viability over a period of several days, and most importantly, develops in an age-specific manner. For mid-gestation embryos, this includes the normal outgrowth of spinal nerves from the spinal cord and the dorsal root ganglia to their targets in the periphery and the proper determination of skeletal and muscle tissue. 
In this work, we present a method for processing whole embryos of embryonic day (E) E10 to E12 into 300 - 400 micrometer slices for cultivation in a standard tissue culture incubator, which can be studied for up to two days after slice preparation. Critical for the success of this approach is the use of a vibratome to slice each agarose-embedded embryo. This is followed by the cultivation of the slices upon Millicell culture membrane inserts placed upon a small volume of medium, resulting in an interface culture technique. One litter with an average of 7 embryos routinely produces at least 14 slices (2-3 slices of the forelimb region per embryo), which varies slightly due to the age of the embryos as well as to the thickness of the slices. About 80% of the cultured slices show nerve outgrowth, which can be measured througout the culturing period2. Representative results using the tauGFP mouse line are demonstrated.

We present a method to prepare organotypic slices of mid-gestation mouse embryos for the cultivation and time-lapse imaging of peripheral nerve outgrowth.

器官型切片文化绿色荧光蛋白表达的实时成像周围神经生长的小鼠胚胎

For many purposes, the cultivation of mouse embryos ex vivo as organotypic slices is desirable. For example, we employ a transgenic mouse line (tauGFP) in ...

科研

神经科学

Mechanical Manipulation of Neurons to Control Axonal Development

Cell manipulations and extension of neuronal axons can be accomplished with calibrated glass micro-fibers capable of measuring and applying forces in the 10-1000 &mu;dyne range1,2. Force measurements are obtained through observation of the Hookean bending of the glass needles, which are calibrated by a direct and empirical method3. Equipment requirements and procedures for fabricating, calibrating, treating, and using the needles on cells are fully described. The force regimes previously used and different cell types to which these techniques have been applied demonstrate the flexibility of the methodology and are given as examples for future investigation4-6. The technical advantages are the continuous 'visualization' of the forces produced by the manipulations and the ability to directly intervene in a variety of cellular events. These include direct stimulation and regulation of axonal growth and retraction7; as well as detachment and mechanical measurements on any type of cultured cell8.

Application and direct measurements of forces on neurons in the 2-1000 microdyne range are achieved with high precision using calibrated glass needles. This methodology can be used to control and measure several aspects of axonal development, including axonal initiation, axonal tension, velocity of axonal elongation, and force vectors.

机械操纵控制神经元轴突的发展

Cell manipulations and extension of neuronal axons can be accomplished with calibrated glass micro-fibers capable of measuring and applying forces in the ...

Neuromodulation and Mitochondrial Transport: Live Imaging in Hippocampal Neurons over Long Durations

To understand the relationship between mitochondrial transport and neuronal function, it is critical to observe mitochondrial behavior in live cultured neurons for extended durations1-3. This is now possible through the use of vital dyes and fluorescent proteins with which cytoskeletal components, organelles, and other structures in living cells can be labeled and then visualized via dynamic fluorescence microscopy. For example, in embryonic chicken sympathetic neurons, mitochondrial movement was characterized using the vital dye rhodamine 1234. In another study, mitochondria were visualized in rat forebrain neurons by transfection of mitochondrially targeted eYFP5. However, imaging of primary neurons over minutes, hours, or even days presents a number of issues. Foremost among these are: 1) maintenance of culture conditions such as temperature, humidity, and pH during long imaging sessions; 2) a strong, stable fluorescent signal to assure both the quality of acquired images and accurate measurement of signal intensity during image analysis; and 3) limiting exposure times during image acquisition to minimize photobleaching and avoid phototoxicity.
Here, we describe a protocol that permits the observation, visualization, and analysis of mitochondrial movement in cultured hippocampal neurons with high temporal resolution and under optimal life support conditions. We have constructed an affordable stage-top incubator that provides good temperature regulation and atmospheric gas flow, and also limits the degree of media evaporation, assuring stable pH and osmolarity. This incubator is connected, via inlet and outlet hoses, to a standard tissue culture incubator, which provides constant humidity levels and an atmosphere of 5-10% CO2/air. This design offers a cost-effective alternative to significantly more expensive microscope incubators that don't necessarily assure the viability of cells over many hours or even days. To visualize mitochondria, we infect cells with a lentivirus encoding a red fluorescent protein that is targeted to the mitochondrion. This assures a strong and persistent signal, which, in conjunction with the use of a stable xenon light source, allows us to limit exposure times during image acquisition and all but precludes photobleaching and phototoxicity. Two injection ports on the top of the stage-top incubator allow the acute administration of neurotransmitters and other reagents intended to modulate mitochondrial movement. In sum, lentivirus-mediated expression of an organelle-targeted red fluorescent protein and the combination of our stage-top incubator, a conventional inverted fluorescence microscope, CCD camera, and xenon light source allow us to acquire time-lapse images of mitochondrial transport in living neurons over longer durations than those possible in studies deploying conventional vital dyes and off-the-shelf life support systems.

We describe a protocol that allows imaging of mitochondria in living neurons via fluorescence microscopy over long durations. Imaging over extended periods is accomplished through lentivirus-mediated expression of a mitochondrially targeted fluorescent protein and use of an inexpensive stage-top incubator that was designed and built in our laboratory.

神经调节和线粒体运输:在较长的时间里，海马神经元的实时成像

To understand the relationship between mitochondrial transport and neuronal function, it is critical to observe mitochondrial behavior in live cultured ...

Imaging Dendritic Spines of Rat Primary Hippocampal Neurons using Structured Illumination Microscopy

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. Technological advances have identified these structures as key elements in neuron connectivity and synaptic plasticity. The quantitative analysis of spine morphology using light microscopy remains an essential problem due to technical limitations associated with light's intrinsic refraction limit. Dendritic spines can be readily identified by confocal laser-scanning fluorescence microscopy. However, measuring subtle changes in the shape and size of spines is difficult because spine dimensions other than length are usually smaller than conventional optical resolution fixed by light microscopy's theoretical resolution limit of 200 nm.
Several recently developed super resolution techniques have been used to image cellular structures smaller than the 200 nm, including dendritic spines. These techniques are based on classical far-field operations and therefore allow the use of existing sample preparation methods and to image beyond the surface of a specimen. Described here is a working protocol to apply super resolution structured illumination microscopy (SIM) to the imaging of dendritic spines in primary hippocampal neuron cultures. Possible applications of SIM overlap with those of confocal microscopy. However, the two techniques present different applicability. SIM offers higher effective lateral resolution, while confocal microscopy, due to the usage of a physical pinhole, achieves resolution improvement at the expense of removal of out of focus light. In this protocol, primary neurons are cultured on glass coverslips using a standard protocol, transfected with DNA plasmids encoding fluorescent proteins and imaged using SIM. The whole protocol described herein takes approximately 2 weeks, because dendritic spines are imaged after 16-17 days in vitro, when dendritic development is optimal. After completion of the protocol, dendritic spines can be reconstructed in 3D from series of SIM image stacks using specialized software.

This article describes a working protocol to image dendritic spines from hippocampal neurons in vitro using Structured Illumination Microscopy (SIM). Super-resolution microscopy using SIM provides image resolution significantly beyond the light diffraction limit in all three spatial dimensions, allowing the imaging of individual dendritic spines with improved detail.

成像大鼠原代海马神经元树突棘使用结构照明显微镜

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

We present a protocol utilizing two-photon excitation time-lapse microscopy to simultaneously visualize the dynamics of axon and myelin injuries in real time. This proposed protocol permits studies of both intrinsic and extrinsic factors which can influence central myelinated axon fate after injury and contribute to permanent clinical disability.

一个<em&gt;离体</em&gt;激光诱导脊髓损伤模型，以评估轴索变性的机制在实时

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

A Protocol for the Administration of Real-Time fMRI Neurofeedback Training

Neurologic disorders are characterized by abnormal cellular-, molecular-, and circuit-level functions in the brain. New methods to induce and control neuroplastic processes and correct abnormal function, or even shift functions from damaged tissue to physiologically healthy brain regions, hold the potential to dramatically improve overall health. Of the current neuroplastic interventions in development, neurofeedback training (NFT) from functional Magnetic Resonance Imaging (fMRI) has the advantages of being completely non-invasive, non-pharmacologic, and spatially localized to target brain regions, as well as having no known side effects. Furthermore, NFT techniques, initially developed using fMRI, can often be translated to exercises that can be performed outside of the scanner without the aid of medical professionals or sophisticated medical equipment. In fMRI NFT, the fMRI signal is measured from specific regions of the brain, processed, and presented to the participant in real-time. Through training, self-directed mental processing techniques, that regulate this signal and its underlying neurophysiologic correlates, are developed. FMRI NFT has been used to train volitional control over a wide range of brain regions with implications for several different cognitive, behavioral, and motor systems. Additionally, fMRI NFT has shown promise in a broad range of applications such as the treatment of neurologic disorders and the augmentation of baseline human performance. In this article, we present an fMRI NFT protocol developed at our institution for modulation of both healthy and abnormal brain function, as well as examples of using the method to target both cognitive and auditory regions of the brain.

The ability to induce and/or control neural plasticity may be critical in future treatments for neurologic disorders and the recovery from brain injury. In this paper, we present a protocol on the use of neurofeedback training with functional magnetic resonance imaging to modulate human brain function.

实时 fMRI 神经训练管理协议

Neurologic disorders are characterized by abnormal cellular-, molecular-, and circuit-level functions in the brain. New methods to induce and control ...

Assay to Measure Nucleocytoplasmic Transport in Real Time within Motor Neuron-like NSC-34 Cells

Nucleocytoplasmic transport refers to the import and export of large molecules from the cell nucleus. Recently, a number of studies have shown a connection between amyotrophic lateral sclerosis (ALS) and impairments in the nucleocytoplasmic pathway. ALS is a neurodegenerative disease affecting the motor neurons and resulting in paralysis and ultimately in death, within 2-5 years on average. Most cases of ALS are sporadic, lacking any apparent genetic linkage, but 10% are inherited in a dominant manner. Recently, hexanucleotide repeat expansions (HREs) in the chromosome 9 open reading frame 72 (C9orf72) gene were identified as a genetic cause of ALS and frontotemporal dementia (FTD). Importantly, different groups have recently proposed that these mutants affect nucleocytoplasmic transport. These studies have mostly shown the final outcome and manifestations caused by HREs on nucleocytoplasmic transport, but they do not demonstrate nuclear transport dysfunction in real time. As a result, only severe nucleocytoplasmic transport deficiency can be determined, mostly due to high overexpression or exogenous protein insertion. 
This protocol describes a new and very sensitive assay to evaluate and quantify nucleocytoplasmic transport dysfunction in real time. The rate of import of a NLS-NES-GFP protein (shuttle-GFP) can be quantified in real time using fluorescent microscopy. This is performed by using an exportin inhibitor, thus allowing the shuttle GFP only to enter the nucleus. To validate the assay, the C9orf72 HRE translated dipeptide repeats, poly(GR) and poly(PR), which have been previously shown to disrupt nucleocytoplasmic transport, were used. Using the described assay, a 50% decrease in the nuclear import rate was observed compared to the control. Using this system, minute changes in nucleocytoplasmic transport can be examined and the ability of different factors to rescue (even partially) a nucleocytoplasmic transport defect can be determined.

This protocol describes a method to sensitively measure the nucleocytoplasmic transport rate within motor neuron-like NSC-34 cells by quantifying the real-time change in the nuclear import of a NLS-NES-GFP protein.

测定在运动神经元样NSC-34细胞中实时测量核细胞质运输

Nucleocytoplasmic transport refers to the import and export of large molecules from the cell nucleus. Recently, a number of studies have shown a ...

Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila

The establishment of functional neuromuscular circuits relies on precise connections between developing motor axons and target muscles. Motor neurons extend growth cones to navigate along specific pathways by responding to a large number of axon guidance cues that emanate from the surrounding extracellular environment. Growth cone target recognition also plays a critical role in neuromuscular specificity. This work presents a standard immunohistochemistry protocol to visualize motor neuron projections of late stage-16 Drosophila melanogaster embryos. This protocol includes a few key steps, including a genotyping procedure, to sort the desired mutant embryos; an immunostaining procedure, to tag embryos with fasciclin II (FasII) antibody; and a dissection procedure, to generate filleted preparations from fixed embryos. Motor axon projections and muscle patterns in the periphery are much better visualized in flat preparations of filleted embryos than in whole-mount embryos. Therefore, the filleted preparation of fixed embryos stained with FasII antibody provides a powerful tool to characterize the genes required for motor axon pathfinding and target recognition, and it can also be applied to both loss-of-function and gain-of-function genetic screens.

Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila

This work details a standard immunohistochemistry method to visualize motor neuron projections of late stage-16 Drosophila melanogaster embryos. The filleted preparation of fixed embryos stained with FasII antibody provides a powerful tool to characterize the genes required for motor axon pathfinding and target recognition during neural development.

胚胎运动神经元轴突投影模式的可视化<em&gt;果蝇</em

The establishment of functional neuromuscular circuits relies on precise connections between developing motor axons and target muscles. Motor neurons ...

Ballistic Labeling of Pyramidal Neurons in Brain Slices and in Primary Cell Culture

It has been reported that the size and shape of dendritic spines is related to their structural plasticity. To identify the morphological structure of pyramidal neurons and dendritic spines, a ballistic labeling technique can be utilized. In the present protocol, pyramidal neurons are labeled with DilC18(3) dye and analyzed using neuronal reconstruction software to assess neuronal morphology and dendritic spines. To investigate neuronal structure, dendritic branching analysis and Sholl analysis are performed, allowing researchers to draw inferences about dendritic branching complexity and neuronal arbor complexity, respectively. The evaluation of dendritic spines is conducted using an automatic assisted classification algorithm integral to the reconstruction software, which classifies spines into four categories (i.e., thin, mushroom, stubby, filopodia). Furthermore, an additional three parameters (i.e., length, head diameter, and volume) are also chosen to assess alterations in dendritic spine morphology. To validate the potential of wide application of the ballistic labeling technique, pyramidal neurons from in vitro cell culture were successfully labeled. Overall, the ballistic labeling method is unique and useful for visualizing neurons in different brain regions in rats, which in combination with sophisticated reconstruction software, allows researchers to elucidate the possible mechanisms underlying neurocognitive dysfunction.

We present a protocol to label and analyze pyramidal neurons, which is critical for evaluating potential morphological alterations in neurons and dendritic spines that may underlie neurochemical and behavioral abnormalities.

脑切片和原细胞培养中金字塔神经元的弹道标记

It has been reported that the size and shape of dendritic spines is related to their structural plasticity. To identify the morphological structure of ...

Axonal Transport of Organelles in Motor Neuron Cultures using Microfluidic Chambers System

Motor neurons (MNs) are highly polarized cells with very long axons. Axonal transport is a crucial mechanism for MN health, contributing to neuronal growth, development, and survival. We describe a detailed method for the use of microfluidic chambers (MFCs) for tracking axonal transport of fluorescently labeled organelles in MN axons. This method is rapid, relatively inexpensive, and allows for the monitoring of intracellular cues in space and time. We describe a step by step protocol for: 1) Fabrication of polydimethylsiloxane (PDMS) MFCs; 2) Plating of ventral spinal cord explants and MN dissociated culture in MFCs; 3) Labeling of mitochondria and acidic compartments followed by live confocal imagining; 4) Manual and semiautomated axonal transport analysis. Lastly, we demonstrate a difference in the transport of mitochondria and acidic compartments of HB9::GFP ventral spinal cord explant axons as a proof of the system validity. Altogether, this protocol provides an efficient tool for studying the axonal transport of various axonal components, as well as a simplified manual for MFC usage to help discover spatial experimental possibilities.

Axonal transport is a crucial mechanism for motor neuron health. In this protocol we provide a detailed method for tracking the axonal transport of acidic compartments and mitochondria in motor neuron axons using microfluidic chambers.

使用微流体腔系统在运动神经元培养物中有机细胞的斧头迁移

Motor neurons (MNs) are highly polarized cells with very long axons. Axonal transport is a crucial mechanism for MN health, contributing to neuronal ...