我们感谢 Silke 克拉森的生态系统分析和评估研究所 (创), RWTH 亚琛为她的帮助建立了该协议中使用的特定于组的入门集。我们还要感谢基尔大学的彼得马丁和劳拉 Schynawa 的合作, 在水螨的实验。我们还感谢技术实验室助理保持实验室运行顺畅, 并准备注册的公司和目录编号。这项工作得到了德国研究基金会 (DFG; 项目 GE 2219/3-1) 的支持。

<ol>
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L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+screening+of+invertebrate+predators+for+multiple+prey+DNA+targets.">Rapid screening of invertebrate predators for multiple prey DNA targets.</a> Mol Ecol. 14 (3), 819-827 (2005).</li></ol>

作者没有什么可透露的。

在这里, 我们提出了一个简单和经济高效的方法, pcr 确定的捕食-猎物的相互作用, 从田间样品通过组特定引物的 rDNA 地区, 可以结合其他 non-molecular 分析相同的标本。但是, 该协议中有几个关键步骤。首先, 保证所用底漆的特殊性是必不可少的。其次, 在胃肠道的制备和随后的 DNA 提取过程中, 避免肠道内容物质的污染和丢失是至关重要的。虽然 cross-sample 污染可能导致对猎物 DNA 的假阳性检测, 但肠?...

捕食-食饵的相互作用, 构成了大多数的营养相互作用和食物网络动力学, 是关键的方面, 以表征物质和能量的通量在整个食物链内和之间的生态系统, 这是生态学的主要目标之一1. 碳和养分的来源和流动的确定是进一步了解生态系统之间的连通性2。然而, 生态系统, 如河流及其汇水区, 不仅与有机物和养分的通量有关, 而且还由生物体的运动3。因此, 生境的改变中断了与这些系统挂钩的资源流动, 这不仅直接而且间接地改变了捕食者-猎物群落的组成, 从而极大地改变了这两个生态系的食物网。例如, 食物网的变化已经被证明与单一捕食物种 (例如, 虹鳟鱼)4的移动有关。这种变化可能威胁生物多样性和水生生态系统的运作。因此, 分析这一领域中的捕食者与猎物的相互作用, 对于确定人类引起的环境变化 (如水管理做法) 对水生生态系统当地生物多样性的影响至关重要。
由于在复杂的系统中跟踪营养关联是困难的, 因此已经建立了几种方法来评估在5字段中的喂养交互。传统上, 在田间觅食相互作用的研究是基于对猎物遗骸的视觉识别在解剖内脏和需要广泛的知识关于形态学猎物多样性。视觉肠内容分析提供了一些消费者群体的资源使用的洞察力 (例如,龙虾的饮食的季节性变化6和鱼7,8或喂养偏好的桡足类)。然而, 消化的物理过程使视觉肠内容分析变得困难, 通常会漏掉软体的猎物-有机体9。对于以液体摄取为食的物种或某些无脊椎动物的消费者, 在进食前密集粉碎他们的食物, 如片, 在肠道内容中对猎物种类的视觉识别是不可能的10。由于这些限制, 分子分析提供了一个有希望的选择。
分子分析现在已经成为一种常见的工具, 允许快速和精确的猎物检测肠道内容。这种技术的范围多种多样: 基于单克隆抗体或聚合酶链反应 (PCR) 的策略经常被使用, 因为它们具有高特异性和敏感性11。开发新的单克隆抗体是时间和成本密集型, 因此, 当抗体不存在11时, 其他分子技术的应用就更有用了。另一种常见的方法是放大脱氧核糖核酸 (脱氧核糖核酸) 的区域, 象核糖体核糖核酸 (RNA) 基因存在于多数种类, 使用普遍引物设置12,13。在使用这种技术时, 通常不可能在混合来源的 DNA14中确定整个捕食生物体的范围。有效的方法, 以避免这种缺点是使用组特定的入门集的遗传肠道内容分析。设计为只放大特定目标群的 DNA 区域并排除所有其他物种15,16, 组特定的引物可在指定组的分类级别上识别捕食生物体, 而无需时间和成本密集型的二次分析。然而, 像所有的肠道内容分析, 这种分析只提供了一个喂养行为的快照。因此, 结合分子肠含量分析与时间自然示踪剂 (例如,稳定同位素) 的分析被认为是有益的1,2。
在这里, 我们描述了一个详细的方法, pcr 调查的捕食-猎物的相互作用使用组特定的引物的核核糖体 DNA (rDNA) 地区与稳定同位素分析的同一标本。我们描述了通过琼脂糖凝胶电泳检测单个猎物群的 DNA。此外, 我们还提供了一个机会, 进一步下游分析 PCR 产品的这种特定的群体特异性底漆适用于任何时候更高的分类分辨率比底漆的特异性是必需的。由于单股 DNA (ssDNA) 片段形成了由其主序17确定的三级构象, 因此由这种基团特异的引物放大的片段的微小变化会导致构象变化。这种变化可以检测到单链构象多态性 (SSCP) 分析与聚丙烯酰胺凝胶17,18, 使更精确的识别猎物生物体 (下至物种水平)。
虽然琼脂糖凝胶电泳是一个常见的和廉价的工具, 可视化 dna 片段和确定其近似长度19, 分辨率取决于 dna 的数量和染色染料使用20。通常, 在使用纯 DNA 样本时, 可视化是直接的, 但是在消费者的肠道中潜在的少量的猎物 dna 可能会使琼脂糖凝胶电泳结果的评分复杂化。尽管如此, 这种检测方法是可行的, 以筛选少量的消费样本从外地的一个或几个猎物群, 但复杂的评分, 使筛选的大量样本的多个猎物群非常时间密集, 从而不切实际.更灵敏的检测方法是通过毛细管电泳自动分析碎片, 另外还允许确定片段的确切长度21。一些微卫星研究表明, 通过使用不同的荧光染料作为标签, 可以通过自动片段分析22,23来检测和确定可比较长度的不同片段. 24。因此, 我们还提出了一个详细的协议, 并行检测 DNA 从多个猎物群使用 PCR 与标记组特定的底漆集和检测通过自动片段分析与自动排序器。此外, 我们提出的案例研究的结果表明, 通过自动片段分析检测猎物的 DNA 是一种方法, 也使相对量化的摄入猎物。

<table>
	<tbody>
		<tr>
			<td>liquid nitrogen</td>
			<td>Any</td>
			<td>NA</td>
			<td>For transport of field samples of macroinvertebrates to the laboratory.</td>
		</tr>
		<tr>
			<td>1.5 ml reaction tubes - Safelock</td>
			<td>Any</td>
			<td>NA</td>
			<td>For collection of consumer specimens in the field and subsequent conservation in liquid nitrogen reaction tubes do not necessarily need to be PCR clean. To avoid exploding of the tubes, the lid of the tubes should be punctured with a needle.</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Any</td>
			<td>NA</td>
			<td>Make sure magnification is suitable to prepare the gastro-intestinaltract of the size of consumer of interest.</td>
		</tr>
		<tr>
			<td>Petri dishes</td>
			<td>Any</td>
			<td>NA</td>
			<td>To dissect the gastro-intestinal tract of consumer specimens under the stereomikroscope.</td>
		</tr>
		<tr>
			<td>Stainless steel foceps: Dumont forceps No. 7</td>
			<td>Bioform</td>
			<td>B40d</td>
			<td>This curved stainless steel forceps can sometimes be very helful to hold specimen fixed inbetween the curved part without puncturing the gastro-intestinal tract.</td>
		</tr>
		<tr>
			<td>Stainless steel foceps: Dumont forceps Electronic No. 5</td>
			<td>Bioform</td>
			<td>B40b</td>
			<td>This fine stainless steel forceps is ideally suited for the preparation of the gastro-intestinal tract of consumer specimens.</td>
		</tr>
		<tr>
			<td>DNA-ExitusPlus</td>
			<td>AppliChem</td>
			<td>A7409,1000RF</td>
			<td>Decontamination solution for the removal of DNA and RNA contaminations</td>
		</tr>
		<tr>
			<td>fuzz-free paper towel</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Lab scale</td>
			<td>Any</td>
			<td>NA</td>
			<td>Precision needs to be at least 0.01 g.</td>
		</tr>
		<tr>
			<td>Microlitre pipettes (0.5-10/10-100/50-200/100-1000 &#956;L)</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Safe-Lock Tubes 2.0 ml</td>
			<td>VWR</td>
			<td>211-2165</td>
			<td>It is crucial that these raction tubes are free of DNA, DNase, RNase and PCR inhibitors (PCR clean)!</td>
		</tr>
		<tr>
			<td>Safe-Lock Tubes 1.5 ml</td>
			<td>VWR</td>
			<td>211-2164</td>
			<td>It is crucial that these raction tubes are free of DNA, DNase, RNase and PCR inhibitors (PCR clean)!</td>
		</tr>
		<tr>
			<td>Sodium chloride &#8805;99.5%, p.a., ACS, ISO</td>
			<td>carlroth</td>
			<td>3957.3</td>
			<td>For salt extraction buffer (SEB) and 5M NaCl-solution required for extraction of DNA.</td>
		</tr>
		<tr>
			<td>Tris(hydroxymethyl)-aminomethane Tris</td>
			<td>carlroth</td>
			<td>4855.2</td>
			<td>For salt extraction buffer (SEB) and TBE buffer</td>
		</tr>
		<tr>
			<td>Microlitre pipettes (0.5-10/10-100/50-200/100-1000 &#956;L)</td>
			<td>carlroth</td>
			<td>8043.1</td>
			<td>For salt extraction buffer (SEB) and TBE buffer</td>
		</tr>
		<tr>
			<td>Boric acid &#8805;99.8 %, p.a., ACS, ISO</td>
			<td>carlroth</td>
			<td>6943.2</td>
			<td>For TBE buffer. Not needed if commercialy available TBE buffer is obtained.</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate (SDS)</td>
			<td>carlroth</td>
			<td>4360.1</td>
			<td>For extraction of DNA</td>
		</tr>
		<tr>
			<td>Proteinase K lyophil.</td>
			<td>carlroth</td>
			<td>7528.1</td>
			<td>Prepare a working solution containing 10 mg/ml.</td>
		</tr>
		<tr>
			<td>TissueLyser II</td>
			<td>Quiagen</td>
			<td>85300</td>
			<td>Bead mill for homogenization of the samples.</td>
		</tr>
		<tr>
			<td>Stainless Steel Beads, 5 mm</td>
			<td>Quiagen</td>
			<td>69989</td>
			<td>For homogenization of samples.</td>
		</tr>
		<tr>
			<td>Heating Thermoshaker</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex Mixer</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Refrigerated centrifuge: himac CT 15 RE</td>
			<td>Hitachi</td>
			<td>NA</td>
			<td>Refrigerated centrifuge used for centrifugation during the extraction of DNA (Protocol 1).</td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>carlroth</td>
			<td>6752.5</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 99.8 %, p.a.</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Water Molecular biology grade (ddH2O)</td>
			<td>AppliChem</td>
			<td>A7398,1000</td>
			<td>nuclease-free (stream sterilized and DEPC treated) water used for re-suspension of DNA and whenever refered to ddH2O within the manuscript</td>
		</tr>
		<tr>
			<td>Unmodified Olegonucleotides</td>
			<td>Eurofins MWG Operon</td>
			<td>NA</td>
			<td>Primers unlabeled</td>
		</tr>
		<tr>
			<td>Modified olegonucleotides</td>
			<td>Metabion International AG</td>
			<td>NA</td>
			<td>Primers labelled</td>
		</tr>
		<tr>
			<td>peqGOLD Taq all inclusive</td>
			<td>VWR Peqlab</td>
			<td>01-1000</td>
			<td>Taq all inclusive for PCR reaction mixtures (reaction buffer Y and S, dNTPs and MgCl2)</td>
		</tr>
		<tr>
			<td>Primus 96 advanced gradient thermocycler or peqStar96x Universal Gradient</td>
			<td>Peqlab</td>
			<td>NA</td>
			<td>Primer sets were originally established on a Primus 96 advanced gradient thermocycler. As this cycler was quite old, we than checked if our primer sets are efficient and specific under the same conditions using the peqSta96x (which also could simulate the older model). However, tests showed that our primers work well and are still specific (see Koester et al. 2013) without using the simulation of the old machine.</td>
		</tr>
		<tr>
			<td>Standard 96 Well PCR Plates</td>
			<td>VWR Peqlab</td>
			<td>732-2879</td>
			<td>Used for PCR reactions.</td>
		</tr>
		<tr>
			<td>Low Profile Tube Stripes 0.15 ml with Flat Cap Stripes</td>
			<td>VWR Peqlab</td>
			<td>732-3223</td>
			<td>Cap stripes used to close the PCR plates.</td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Peqlab</td>
			<td>35-1020</td>
			<td>Used for gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Microwave</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical flask</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Measuring cylinder</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Horizontal electrophoresis unit and respective combs with teeth</td>
			<td>Any</td>
			<td>NA</td>
			<td>For agarose gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Electrophoresis Power Supply PS3002</td>
			<td>Life Technologies</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethidium bromide solution 1 %</td>
			<td>carlroth</td>
			<td>2218.1</td>
			<td>Used to prepare staining bath for agarose gels.</td>
		</tr>
		<tr>
			<td>Formamide</td>
			<td>carlroth</td>
			<td>6749.1</td>
			<td>Needded for the denaturation buffer for SSCP analyses.</td>
		</tr>
		<tr>
			<td>Bromphenol blue</td>
			<td>AppliChem</td>
			<td>A3640.0010</td>
			<td>Needed for the loading dye for agarose gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>carlroth</td>
			<td>4621.1</td>
			<td>Needed for the loading dye for agarose gel electrophoresis.</td>
		</tr>
		<tr>
			<td>100 bp-DNA-Ladder extended</td>
			<td>carlroth</td>
			<td>T835.1</td>
			<td>As size standard for agarose gel electrophoresis.</td>
		</tr>
		<tr>
			<td>UV-Documentation system</td>
			<td>Any</td>
			<td>NA</td>
			<td>To visualize gel electrophoresis results.</td>
		</tr>
		<tr>
			<td>Rotiphorese NF-Acrylamide/Bis-solution 40 % (29:1)</td>
			<td>carlroth</td>
			<td>A121.1</td>
			<td>For the preparation of polyacrylamid gels.</td>
		</tr>
		<tr>
			<td>Ammonium peroxydisulphate</td>
			<td>carlroth</td>
			<td>9592.2</td>
			<td>For the preparation of polyacrylamid gels.</td>
		</tr>
		<tr>
			<td>foldback clips (32 mm)</td>
			<td>Any</td>
			<td>NA</td>
			<td>For the preparation of polyacrylamid gels.</td>
		</tr>
		<tr>
			<td>square-shaped plastic box (21 &#215; 6.5 &#215; 5 cm)</td>
			<td>Any</td>
			<td>NA</td>
			<td>For the preparation of polyacrylamid gels.</td>
		</tr>
		<tr>
			<td>Tetramethylethylenediamine (TEMED)</td>
			<td>carlroth</td>
			<td>23.67.1</td>
			<td>For the preparation of polyacrylamid gels.</td>
		</tr>
		<tr>
			<td>Beaker</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>RC 10 Digital chiller</td>
			<td>VWR</td>
			<td>462-0138</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Vertical electrophoresis unit P10DS (OWL Separation Systems)</td>
			<td>VWR</td>
			<td>700-2361</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Notched glass plate</td>
			<td>VWR</td>
			<td>730-0261</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Blank glass plate</td>
			<td>VWR</td>
			<td>730-0260</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Spacers</td>
			<td>VWR</td>
			<td>730-0262</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Comb with 25 teeth</td>
			<td>VWR</td>
			<td>730-0294</td>
			<td>For SSCP analyses using polyacrylamide gel electrophoresis.</td>
		</tr>
		<tr>
			<td>Shaking platform</td>
			<td>Any</td>
			<td>NA</td>
			<td>For constant shaking of the staining bath.</td>
		</tr>
		<tr>
			<td>GelStar Nucleic Acid Stain (Lonza Rockland, Inc.)</td>
			<td>Biozym</td>
			<td>850535 (50535)</td>
			<td>For staining of polyacrylamide gels.</td>
		</tr>
		<tr>
			<td>GenomeLab DNA Size Standard Kit 400bp</td>
			<td>AB Sciex</td>
			<td>608098</td>
			<td>For automated fragment analyses. Size stanard for Batch B.</td>
		</tr>
		<tr>
			<td>GenomeLab DNA Size Standard Kit 600bp</td>
			<td>AB Sciex</td>
			<td>608095</td>
			<td>For automated fragment analyses. Size stanard for Batch A.</td>
		</tr>
		<tr>
			<td>Sample Loading Solution (SLS)</td>
			<td>AB Sciex</td>
			<td>608082</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>Sequenzing plate - 96 Well Polypropylene PCR Microplate</td>
			<td>Costar</td>
			<td>6551</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>Plate centrifuge, PerfectSpin P</td>
			<td>VWR Peqlab</td>
			<td>NA</td>
			<td>mini plate centrifuge used to spin down PCR products.</td>
		</tr>
		<tr>
			<td>Buffer plate - 96 Well EIA/RIA Clear Flat Bottom Polystyrene Not Treated Microplate</td>
			<td>Corning</td>
			<td>9017</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>GenomeLab Seperation buffer</td>
			<td>AB Sciex</td>
			<td>608012</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>Separation Gel - LPAI</td>
			<td>AB Sciex</td>
			<td>608010</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>Sequenzer - CEQ8000 Genetic Analysis System</td>
			<td>Beckman Coulter</td>
			<td>NA</td>
			<td>For automated fragment analyses.</td>
		</tr>
		<tr>
			<td>GeneMarker V1.95</td>
			<td>Softgenetics</td>
			<td>NA</td>
			<td>To analyze results of automated fragment analyses.</td>
		</tr>
	</tbody>
</table>

laboratory protocol for genetic gut content analyses of aquatic macroinvertebrates using group-specific rdna primers

分析食物网对于更好地了解生态系统是至关重要的。例如, 食物网络的相互作用可能会因非土著物种的入侵而发生严重的变化。然而, 在许多情况下, 对场捕食者-食饵相互作用的精确识别是困难的。这些分析通常是基于对肠道内容的视觉评估或稳定同位素比率的分析 (δ15N 和δ13C)。这些方法需要对个别捕食生物体的形态多样性或同位素特征进行全面的了解, 从而导致对猎物生物体的准确识别的障碍。视觉肠道内容分析, 特别是低估了软体的猎物有机体, 因为浸泡, 摄食和消化的猎物有机体, 使鉴定的特定物种很难。因此, 聚合酶链反应 (PCR) 为基础的策略, 例如使用组特定的入门集, 提供了一个强大的工具, 调查食物网络互动。在这里, 我们描述了详细的协议, 以调查的肠道内容的动物消费者从现场使用的组特定的入门套核核糖体脱氧核糖核酸 (rDNA)。DNA 可以从整个标本中提取 (在小分类群的情况下), 或者从野外采集的标本的肠道内容。dna 模板的存在和功能的效率需要直接从被测试的个体中得到确认, 使用针对各自 dna 亚基的通用引物集。我们还证明, 被消耗的猎物可以进一步确定的物种水平通过 PCR 与未修改的组特异性引物结合随后单链构象多态性 (SSCP) 分析使用聚丙烯酰胺凝胶。此外, 我们还表明, 使用不同的荧光染料作为标签, 可以通过自动片段分析从多个肠道含量样本中对不同猎物群的 DNA 片段进行平行筛选。

我们成功地使用了本协议中描述的步骤进行不同研究中的饮食分析。在本节中, 我们将介绍该协议不同部分的适用性的示例。
以 SSCP 分析为例, 演示了作者28建立的组特定引物集的有效性以及对 PCR 产物进行进一步下游分析的潜力, 并进行了饲喂试验。个体的Dikerogammarus villosus作为捕食者和Caenis的?...

Watch this Scientific Journal Video about Laboratory Protocol for Genetic Gut Content Analyses of Aquatic Macroinvertebrates Using Group-specific rDNA Primers at JoVE.com

Laboratory Protocol for Genetic Gut Content Analyses of Aquatic Macroinvertebrates Using Group-specific rDNA Primers

无脊椎动物最常见的肠道成分分析是可视的。由于需要对猎物生物体的形态多样性有强烈的了解, 他们会想念身体柔软的猎物, 由于对猎物的强烈粉碎, 对包括片在内的一些生物体来说几乎是不可能的。我们提供了详细的, 新的遗传方法, 动物猎物识别在饮食中的片。

用基团特异 rDNA 引物对水生无脊椎动物进行遗传肠道含量分析的实验室规程

Analyzing food webs is essential for a better understanding of ecosystems. For example, food web interactions can undergo severe changes caused by the ...

laboratory-protocol-for-genetic-gut-content-analyses-aquatic

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

8.8K 次观看.  University of Koblenz-Landau. 无脊椎动物最常见的肠道成分分析是可视的。由于需要对猎物生物体的形态多样性有强烈的了解, 他们会想念身体柔软的猎物, 由于对猎物的强烈粉碎, 对包括片在内的一些生物体来说几乎是不可能的。我们提供了详细的, 新的遗传方法, 动物猎物识别在饮食中的片。

视频: Laboratory Protocol for Genetic Gut Content Analyses of Aquatic Macroinvertebrates Using Group-specific rDNA Primers

Method for Culture of Early Chick Embryos ex vivo (New Culture)

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  the formation and patterning of brain, neural tube, somite and heart primordia. Applications of chick embryo culture include electroporation of DNA or RNA constructs in order to analyze gene function, grafts of growth factor coated beads such as FGFs and BMPs , as well as whole mount in situ hybridization and immunohistochemistry. This video demonstrates the different steps in chick embryo culture; First, the embryo is explanted in saline. Then, the embryo is centered on a glass ring. The membranes surrounding the embryo are lifted along the walls of the ring. The ring is then placed in a culture dish containing a pool of albumine. The culture dish is sealed and placed in a humid chamber, where the embryo is cultured for up to 24 hrs. Finally, the embryo is removed from the ring, fixed and processed for further applications. A troubleshooting guide is also presented.

Method for Culture of Early Chick Embryos ex vivo New Culture

This video demonstrates New culture, a method by which chick embryos are cultured outside the egg for up to 24 hr. This method enables one to study early development (primitive streak to 14 som.), a period corresponding to E7-9 in mouse. Applications of this technique include electroporation, in situ hybridization and immunohistochemistry.

文化早期鸡胚体外（新文化）的方法

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ...

科研

生物学

Double Whole Mount in situ Hybridization of Early Chick Embryos

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  gene expression in brain, neural tube, somite and heart primordia formation. This video demonstrates the different steps in 2-color whole mount in situ hybridization; First, the embryo is dissected from the egg and fixed in paraformaldehyde. Second, the embryo is processed for prehybridization. The embryo is then hybridized with two different probes, one coupled to DIG, and one coupled to FITC.  Following overnight hybridization, the embryo is incubated with DIG coupled antibody. Color reaction for DIG substrate is performed, and the region of interest appears blue. The embryo is then incubated with FITC coupled antibody. The embryo is processed for color reaction with FITC, and the region of interest appears red. Finally, the embryo is fixed and processed for phtograph and sectioning. A troubleshooting guide is also presented.

This video demonstrates 2-color whole mount in situ hybridization, a method by which the spatial and temporal expression pattern of 2 different genes can be visualized in young chick embryos. This method was originally introduced by David Wilkinson, Domingos Henrique, Phil Ingham and David Ish -Horowicz.

双整装原位杂交技术在早期鸡胚

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

一个神经元和星形胶质细胞共培养检测神经毒性的高含量分析

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System 

Understanding the roles of human DNA repair proteins in genetic pathways is a formidable challenge to many researchers. Genetic studies in mammalian systems have been limited due to the lack of readily available tools including defined mutant genetic cell lines, regulatory expression systems, and appropriate selectable markers. To circumvent these difficulties, model genetic systems in lower eukaryotes have become an attractive choice for the study of functionally conserved DNA repair proteins and pathways. We have developed a model yeast system to study the poorly defined genetic functions of the Werner syndrome helicase-nuclease (WRN) in nucleic acid metabolism. Cellular phenotypes associated with defined genetic mutant backgrounds can be investigated to clarify the cellular and molecular functions of WRN through its catalytic activities and protein interactions. The human WRN gene and associated variants, cloned into DNA plasmids for expression in yeast, can be placed under the control of a regulatory plasmid element. The expression construct can then be transformed into the appropriate yeast mutant background, and genetic function assayed by a variety of methodologies. Using this approach, we determined that WRN, like its related RecQ family members BLM and Sgs1, operates in a Top3-dependent pathway that is likely to be important for genomic stability. This is described in our recent publication [1] at <a href="http://www.impactaging.com">www.impactaging.com</a>. Detailed methods of specific assays for genetic complementation studies in yeast are provided in this paper.

Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System

Genetic studies in yeast can be employed to investigate the molecular and cellular functions of human genes in cellular DNA metabolism. Methods are described for the genetic characterization of the human WRN gene product defective in the premature aging disorder Werner syndrome in functionally conserved pathways using yeast as a tractable model system.

人类DNA修复蛋白的遗传研究利用酵母作为模型系统

Understanding the roles of human DNA repair proteins in genetic pathways is a formidable challenge to many researchers.  Genetic studies in mammalian ...

DNA Extraction from Paraffin Embedded Material for Genetic and Epigenetic Analyses

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number gains and losses and DNA methylation. Advances in high-throughput, genome-wide profiling technologies, such as microarrays, have significantly improved our ability to identify and detect these specific alterations. However as technology continues to improve, a limiting factor remains sample quality and availability. Furthermore, follow-up clinical information and disease outcome are often collected years after the initial specimen collection. Specimens, typically formalin-fixed and paraffin embedded (FFPE), are stored in hospital archives for years to decades. DNA can be efficiently and effectively recovered from paraffin-embedded specimens if the appropriate method of extraction is applied. High quality DNA extracted from properly preserved and stored specimens can support quantitative assays for comparisons of normal and diseased tissues and generation of genetic and epigenetic signatures 1. To extract DNA from paraffin-embedded samples, tissue cores or microdissected tissue are subjected to xylene treatment, which dissolves the paraffin from the tissue, and then rehydrated using a series of ethanol washes. Proteins and harmful enzymes such as nucleases are subsequently digested by proteinase K. The addition of lysis buffer, which contains denaturing agents such as sodium dodecyl sulfate (SDS), facilitates digestion 2. Nucleic acids are purified from the tissue lysate using buffer-saturated phenol and high speed centrifugation which generates a biphasic solution. DNA and RNA remain in the upper aqueous phase, while proteins, lipids and polysaccharides are sequestered in the inter- and organic-phases respectively. Retention of the aqueous phase and repeated phenol extractions generates a clean sample. Following phenol extractions, RNase A is added to eliminate contaminating RNA. Additional phenol extractions following incubation with RNase A are used to remove any remaining enzyme. The addition of sodium acetate and isopropanol precipitates DNA, and high speed centrifugation is used to pellet the DNA and facilitate isopropanol removal. Excess salts carried over from precipitation can interfere with subsequent enzymatic assays, but can be removed from the DNA by washing with 70% ethanol, followed by centrifugation to re-pellet the DNA 3. DNA is re-suspended in distilled water or the buffer of choice, quantified and stored at -20&deg;C. Purified DNA can subsequently be used in downstream applications which include, but are not limited to, PCR, array comparative genomic hybridization 4 (array CGH), methylated DNA Immunoprecipitation (MeDIP) and sequencing, allowing for an integrative analysis of tissue/tumor samples.

This video demonstrates the protocol for DNA extraction from formalin-fixed paraffin-embedded material. This is a multi-day procedure in which tissue sections are deparaffinized with xylene, rehydrated with ethanol and treated with proteinase K to purify and isolate DNA for subsequent gene-specific or genome-wide analysis.

从石蜡包埋材料的遗传和表观遗传分析的DNA提取

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number ...

Evisceration of Mouse Vitreous and Retina for Proteomic Analyses

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is a highly aqueous extracellular matrix overlying the retina where intraocular as well as extraocular proteins accumulate during disease.1-3 Abnormal interactions between vitreous and retina underlie several diseases such as retinal detachment, proliferative diabetic retinopathy, uveitis, and proliferative vitreoretinopathy.1,4 The relative mouse vitreous volume is significantly smaller than the human vitreous (Figure 1), since the mouse lens occupies nearly 75% of its eye.5 This has made biochemical studies of mouse vitreous challenging. In this video article, we present a technique to dissect and isolate the mouse vitreous from the retina, which will allow use of transgenic mouse models to more clearly define the role of this extracellular matrix in the development of vitreoretinal diseases.

The dissection technique illustrates evisceration of the vitreous, retina, and lens from the mouse eye, separation by centrifugation, and characterization with protein assays.

眼内容剜除小鼠玻璃体和视网膜蛋白质组分析

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is ...

Generation of Human Cardiomyocytes: A Differentiation Protocol from Feeder-free Human Induced Pluripotent Stem Cells

In order to investigate the events driving heart development and to determine the molecular mechanisms leading to myocardial diseases in humans, it is essential first to generate functional human cardiomyocytes (CMs). The use of these cells in drug discovery and toxicology studies would also be highly beneficial, allowing new pharmacological molecules for the treatment of cardiac disorders to be validated pre-clinically on cells of human origin. Of the possible sources of CMs, induced pluripotent stem (iPS) cells are among the most promising, as they can be derived directly from readily accessible patient tissue and possess an intrinsic capacity to give rise to all cell types of the body 1. Several methods have been proposed for differentiating iPS cells into CMs, ranging from the classical embryoid bodies (EBs) aggregation approach to chemically defined protocols 2,3. In this article we propose an EBs-based protocol and show how this method can be employed to efficiently generate functional CM-like cells from feeder-free iPS cells.

Pluripotent stem cells, either embryonic or induced pluripotent stem (iPS) cells, constitute a valuable source of human differentiated cells, including cardiomyocytes. Here, we will focus on cardiac induction of iPS cells, showing how to use them to obtain functional human cardiomyocytes through an embryoid bodies-based protocol.

人类心肌细胞的生成:从馈线人类诱导多能干细胞的分化协议

In order to investigate the events driving heart development and to determine the molecular mechanisms leading to myocardial diseases in humans, it is ...

DNA Electroporation, Isolation and Imaging of Myofibers

Mature muscle has a unique structure that is amenable to live cell imaging. Herein, we describe the experimental protocol for expressing fluorescently labeled proteins in the flexor digitorum brevis (FDB) muscle. Conditions have been optimized to provide a large number of high quality myofibers expressing the electroporated plasmid while minimizing muscle damage. The method employs fluorescent tags on various proteins. Combining this expression method with high resolution confocal microscopy permits live cell imaging, including imaging after laser-induced damage. Fluorescent dyes combined with imaging of fluorescently-tagged proteins provides information regarding the basic structure of muscle and its response to stimuli.

This protocol utilizes electroporation to introduce and express fluorescently labeled proteins in mouse muscle fibers. Following recovery after electroporation, fibers are isolated. Individual fibers are then imaged using high resolution confocal microscopy to visualize muscle structure.

DNA电穿孔，肌纤维的分离和成像

Mature muscle has a unique structure that is amenable to live cell imaging. Herein, we describe the experimental protocol for expressing fluorescently ...

Cellular Redox Profiling Using High-content Microscopy

Reactive oxygen species (ROS) regulate essential cellular processes including gene expression, migration, differentiation and proliferation. However, excessive ROS levels induce a state of oxidative stress, which is accompanied by irreversible oxidative damage to DNA, lipids and proteins. Thus, quantification of ROS provides a direct proxy for cellular health condition. Since mitochondria are among the major cellular sources and targets of ROS, joint analysis of mitochondrial function and ROS production in the same cells is crucial for better understanding the interconnection in pathophysiological conditions. Therefore, a high-content microscopy-based strategy was developed for simultaneous quantification of intracellular ROS levels, mitochondrial membrane potential (&#916;&#936;m) and mitochondrial morphology. It is based on automated widefield fluorescence microscopy and image analysis of living adherent cells, grown in multi-well plates, and stained with the cell-permeable fluorescent reporter molecules CM-H2DCFDA (ROS) and TMRM (&#916;&#936;m and mitochondrial morphology). In contrast with fluorimetry or flow-cytometry, this strategy allows quantification of subcellular parameters at the level of the individual cell with high spatiotemporal resolution, both before and after experimental stimulation. Importantly, the image-based nature of the method allows extracting morphological parameters in addition to signal intensities. The combined feature set is used for explorative and statistical multivariate data analysis to detect differences between subpopulations, cell types and/or treatments. Here, a detailed description of the assay is provided, along with an example experiment that proves its potential for unambiguous discrimination between cellular states after chemical perturbation.

This paper presents a high-content microscopy workflow for simultaneous quantification of intracellular ROS levels, as well as mitochondrial membrane potential and morphology &#8211; jointly referred to as mitochondrial morphofunction &#8211; in living adherent cells using the cell-permeant fluorescent reporter molecules 5-(and-6)-chloromethyl-2&#39;,7&#39;-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA) and tetramethylrhodamine methylester (TMRM).

使用高含量显微镜的细胞氧化还原分析

Reactive oxygen species (ROS) regulate essential cellular processes including gene expression, migration, differentiation and proliferation. However, ...

A Protocol for Laboratory Housing of Turquoise Killifish (Nothobranchius furzeri)

The development of husbandry practices in non-model laboratory fish used for experimental purposes has greatly benefited from the establishment of reference fish model systems, such as zebrafish and medaka. In recent years, an emerging fish &#8211; the turquoise killifish (Nothobranchius furzeri) &#8211; has been adopted by a growing number of research groups in the fields of biology of aging and ecology. With a captive life span of 4 - 8 months, this species is the shortest-lived vertebrate raised in captivity and allows the scientific community to test &#8211; in a short time &#8211; experimental interventions that can lead to alterations of the aging rate and life expectancy. Given the unique biology of this species, characterized by embryonic diapause, explosive sexual maturation, marked morphological and behavioral sexual dimorphism - and their relatively short adult life span -&#160;ad hoc husbandry practices are in urgent demand. This protocol reports a set of key husbandry measures that allow optimal turquoise killifish laboratory care, enabling the scientific community to adopt this species as a powerful laboratory animal model.

A Protocol for Laboratory Housing of Turquoise Killifish Nothobranchius furzeri

Laboratory housing of turquoise killifish can be scaled up&#160;to house and efficiently raise thousands of individual fish in a centralized water filtration system, employing the same infrastructure used for standard zebrafish facilities. Here we detail a list of standardized procedures that allow efficient killifish maintenance.