技术目标显微注射到显影<em>爪</em>肾
1Department of Pediatrics, Pediatric Research Center,University of Texas McGovern Medical School, 2Program in Genes & Development,University of Texas Graduate School of Biomedical Sciences, 3Program in Cell & Regulatory Biology,University of Texas Graduate School of Biomedical Sciences, 4Department of Genetics,University of Texas MD Anderson Cancer Center
Summary
Here, we present a protocol to use fate maps and lineage tracers to target injections into individual blastomeres that give rise to the kidney of Xenopus laevis embryos.
Abstract
的非洲爪 蟾 （蛙）中，前肾，胚胎肾由单个肾的，并且可以用作用于肾脏疾病的模型。 爪蟾胚胎是大的，外部发展，并且可以通过微注射或外科手术容易地操纵。此外，命运地图已经建立了早期的爪蟾胚胎。靶向显微注射到单个卵裂球，最终将产生的器官或感兴趣的组织可被用于选择性地过表达或该受限制区域内的击倒的基因表达，从而降低在发育中的胚胎的其余部分次级效应。在这个协议中，我们描述了如何利用建立的爪蟾的命运映射到显影爪蟾肾（该头肾），通过显微注射到目标的4和8细胞胚胎卵裂球专用。沿袭示踪剂的注入使得注入的具体目标的验证。胚胎已经开发到阶段38后 – 40，整个安装免疫染色被用于可视化pronephric发展，通过靶向的细胞的前肾的贡献可以被评估。同样的技术可以适于除了前肾靶向其它组织类型。
Introduction
非洲爪蟾胚胎肾中，前肾，是研究肾脏发育和疾病的良好模式。胚胎外部发展，在尺寸是大的，可以大量生产，并通过微注射或外科手术容易操纵。此外，治在哺乳动物和两栖动物肾脏发育的基因是保守的。哺乳动物的肾脏通过三个阶段进行：在头肾，中肾，后肾和1，而两栖类胚胎有前肾和成人两栖动物有后肾。这些肾脏形式的基本滤波单元是肾，和哺乳动物和两栖类所需要的相同的信号级联和电感事件接受nephrogenesis 2，3， 爪蟾前肾包含近端，中间，远端和连接管组成的单肾，和血管球（类似于哺乳动物肾小球）1，4-6（ 图1 </str翁>）。大存在于非洲爪蟾前肾单肾使得它适合作为用于参与肾发育和疾病过程的基因的研究中一个简单的模型。
细胞命运的地图已经建立了早期的爪蟾胚胎，并且是免费提供的Xenbase 7-11在线。在这里，我们描述了用于谱系示踪剂定位的显影爪前肾的显微注射的技术，虽然同样的技术可以适用于针对其它组织，如心脏或眼睛。谱系示踪剂是标签（包括活体染料，荧光标记的葡聚糖，组织化学可检测的酶，和mRNA编码荧光蛋白），可以注射到早期卵裂球，使该细胞的后代的发育过程中的可视化。这个协议利用MEM-RFP的mRNA，编码膜靶向红色荧光蛋白12，作为一个谱系示踪剂。有针对性的显微注射技术在这里描述的4-和8细胞胚胎niques单个卵裂球可以用于注射吗啉击倒的基因表达，或与外源RNA过表达感兴趣的基因。通过注入腹侧，植物卵裂球，主要是胚胎的前肾将有针对性，留下对侧前肾作为发育控制。示踪剂联合注射验证正确的卵裂球注射，并显示该组织中的胚胎从卵裂球注入出现，验证了前肾定位。在头肾的免疫染色允许有多好pronephric肾小管已经有针对性的可视化。过度表达和敲低效果然后可以对胚，其用作发育控制的对侧得分，并且可以用于计算pronephric索引13。细胞命运地图的可用性允许使用这种有针对性的显微注射技术对靶组织OTH尔比前肾，和荧光示踪剂的共注射允许有针对性的显微注射到每个组织分析前进行验证。
期间胚胎显微注射，发育温度应严格调节，因为爪蟾发展的速率在 很大程度上取决于它14。 （ – 16°C 14）为4和8细胞注射，因为开发时间减慢的胚胎应该稍凉培养。在22℃，从第1阶段（1细胞）的开发时间到阶段3（4细胞）是约2小时，同时在16℃下的开发时间到阶段3是约4小时。这需要大约15分钟从4细胞的胚胎去8芯（4级），胚胎在22°C，但在16℃，大约需要30分钟。同样地，在22℃，只需要30分钟的8细胞胚胎进步到16细胞胚胎（阶段5）。这个时间是在16℃增加至45分钟。该refore，是有用的减缓胚胎的发育率，以使有足够的时间在8细胞期注射前胚胎进步到16单元的阶段。此外，生长温度可以调节，以加快或减慢胚胎发育，直至肾脏已发育完全。
蝌蚪级爪蟾胚胎的表皮是相对透明的，允许未经组织15的清扫或清除显影前肾的容易成像。由于爪蟾胚胎的相对透明度，活细胞成像也是可行16,17。整个安装免疫染色以可视化的前肾可能带有该标签的近端，中间，远端和舞台的连接管38建立抗体- 40胚胎允许pronephric发展评价靶基因表达的操作后爪蟾胚胎18-20。
Protocol
下面的协议已获得得克萨斯大学健康科学中心在休斯顿的中心实验室动物医学动物福利委员会，作为机构护理和使用委员会大学（协议＃：HSC-AWC-13-135）。 1.识别和选择卵裂球的肾靶向注射之前产生的胚胎，使用爪蟾发展21的正常表理解在胚胎早期的细胞分裂的方向。或者，在Xenbase 11 爪蟾的早期发育阶段的访问的图。 访问Xenbase 11交互?…
Representative Results
的4-和8-细胞爪蟾胚胎用MEM-RFP的mRNA显微注射表现出不同水平的靶向前肾的。 图4示出了级40的胚胎与正确的MEM-RFP的mRNA表达模式。胚胎在左腹侧卵裂球（ 图4A）注射，并分类为MEM-RFP的mRNA的适当的表达模式。除了在近端，中间，远端表达MEM-RFP与连接肾脏肾小管，正常注射的胚胎预计将显示荧光的头部，躯干和尾部的表皮。它们也应显示在…
Discussion
针对发展中爪蟾胚胎的前肾依赖于识别和注入正确的卵裂球。 8细胞胚胎的卵裂球V2的注射靶向左侧前肾18。这留下对侧右前肾作为内部对照。如果啉拦截或RNA表达用于改变肾发展，对侧右前肾可用于基因敲除或过表达的影响进行比较的左前肾。在这种情况下，如不匹配的控制啉或显性负RNA构建适当的控制应除了对侧内部控制用于分析基因表达的变化的结果。由于爪蟾胚胎的?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
这项工作是由儿科得克萨斯麦戈文医学院的大学卫生署授予NIDDK（K01DK092320）和启动资金的国家机构提供支持。
Materials
| Sodium chloride | Fisher | S271-3 | |
| Potassium chloride | Fisher | P217-500 | |
| Magnesium sulfate | Fisher | M63-500 | |
| Calcium chloride | Fisher | C79-500 | |
| HEPES | Fisher | BP310-500 | |
| EDTA | Fisher | S311-500 | |
| Gentamycin solution, 50 mg/mL | Amresco | E737-20ML | |
| L-Cysteine, 99%+ | Acros Organics | 52-90-4 | |
| Ficoll | Fisher | BP525-100 | |
| 100 mm x 15 mm Petri dish | Fisher | FB0875712 | |
| Mini Fridge II | Boekel | 260009 | Benchtop incubator for embryos. |
| Gap43-RFP plasmid | For making tracer RNA. Ref: Davidson et al., 2006. | ||
| Rhodamine dextran, 10,000 M.W. | Invitrogen | D1817 | Tracer. |
| Molecular biology grade, USP sterile purified water | Corning | 46-000-CI | |
| 7" Drummond replacement tubes | Drummond | 3-000-203-G/XL | Microinjection needles. |
| Needle puller | Sutter Instruments | P-30 | |
| Fine forceps | Dumont | 11252-30 | For breaking microinjection needle tip. |
| Nanoject II | Drummond | 3-000-204 | Microinjector. |
| Mineral oil, heavy | Fisher | CAS 8042-47-5 | Oil for needles. |
| 27G monoject hypodermic needle | Covidien | 8881200508 | For loading mineral oil into microinjection needle. |
| 5 mL Luer-Lok syringe | BD | 309646 | For loading mineral oil into microinjection needle. |
| 60 mm x 15 mm Petri dish | Fisher | FB0875713A | |
| 800 micron polyester mesh | Small Parts | CMY-0800-C | |
| Transfer pipets | Fisher | 13-711-7M | For transferring embryos. Cut off the tip so that the embryos are easily taken up by the pipette. |
| 6-well cell culture plate | Nest Biotechnology | ||
| MOPS | Fisher | BP308-500 | |
| EGTA | Acros Organics | 67-42-5 | |
| Formaldehyde | Fisher | BP531-500 | |
| 15 mm x 45 mm screw thread vial | Fisher | 03-339-25B | For fixing, staining, and storing embryos. |
| 24-well cell culture plate | Nest Biotechnology | ||
| Benzocaine | Spectrum | BE130 | |
| Ethanol | Fisher | BP2818-4 | |
| Methanol | Fisher | A412-4 | |
| Phosphate buffered saline (PBS) 1X powder | Fisher | BP661-50 | |
| Bovine serum albumen | Fisher | BP1600-100 | |
| Triton X-100 | Fisher | BP151-500 | |
| 3D mini rocker, model 135 | Denville Scientific | 57281 | |
| Goat serum, New Zealand origin | Invitrogen | 16210064 | |
| Sodium azide | Fisher | S227I-25 | |
| Monoclonal 3G8 antibody | European Xenopus Resource Centre | Primary antibody to label proximal tubules. | |
| Monoclonal 4A6 antibody | European Xenopus Resource Centre | Primary antibody to label distal tubule and duct. | |
| anti-RFP pAb, purified IgG/rabbit | MBL | PM005 | Primary antibody to label Gap43-RFP tracer. |
| Alexa Fluor 488 goat anti-mouse IgG | Life Technologies | A11001 | Secondary antibody to label distal tubule and duct. |
| Alexa Fluor 555 goat anti-rabbit IgG | Life Technologies | A21428 | Secondary antibody to label Gap43-RFP tracer. |
| 9 cavity spot plate | Corning | 7220-85 | |
| Benzyl benzoate | Fisher | 105862500 | Optional – for clearing embryos |
| Benzyl alcohol | Fisher | A396-500 | Optional – for clearing embryos |
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Cite This Article
DeLay, B. D., Krneta-Stankic, V., Miller, R. K. Technique to Target Microinjection to the Developing Xenopus Kidney. J. Vis. Exp. (111), e53799, doi:10.3791/53799 (2016).