Summary

准备和注射 Culex 蚊子的胚胎,使用CRISPR/Cas9产生空突变

Published: September 10, 2020
doi:

Summary

CRISPR/Cas9越来越多地用于非模型生物体的基因功能特征。该协议描述了如何产生 Culex皮皮恩斯的淘汰线,从准备注射混合,获得和注射蚊子胚胎,以及如何后方,交叉和屏幕注射蚊子及其后代所需的突变。

Abstract

Culex 蚊子是多种疾病的主要传播媒介,这些疾病对人类和动物健康产生了负面影响,包括西尼罗河病毒和由犬心虫和象虫病等纤维线虫引起的疾病。最近,CRISPR/Cas9基因组编辑被用来诱导现场定向突变,通过注射一种Cas9蛋白,该蛋白质已经与导引RNA(gRNA)复合成几个昆虫物种的新鲜胚胎,包括属于 阿诺菲勒斯 家族和 伊蚊的蚊子。操纵和注射 Culex 蚊子稍微困难一些,因为这些蚊子将卵子直立在木筏上,而不是像其他种类的蚊子那样单独。在这里,我们描述如何设计gRNA,用Cas9蛋白复合它们,诱导 Culex皮皮恩斯 雌性蚊子产卵,以及如何准备和注射新铺设的胚胎与Cas9/gRNA进行微注射。我们还描述了如何饲养和筛选注射蚊子的所需突变。具有代表性的结果表明,该技术可用于诱导 Culex 蚊子基因组中的部位定向突变,并稍作修改,也可用于在其他蚊子物种中产生空突变体。

Introduction

Culex蚊子分布在世界各地的温带和热带地区,传播几种致命的病毒,包括西尼罗河病毒1,圣路易斯脑炎2,以及引起犬心虫3和象虫病4的线虫。库莱克斯皮皮恩斯综合体的成员,其中包括Cx.五角星,Cx.皮皮恩斯皮皮恩斯Cx.皮皮恩斯摩尔斯,显示其生物学的许多方面惊人的变化。例如,虽然Cx.五角星Cx.皮皮恩斯骚扰者不能进入过冬的休眠5,6,Cx.皮皮恩斯皮皮恩斯显示强大的季节性反应,并进入糖尿病,以回应短天7,8。此外,Cx.皮皮恩斯的骚扰往往更人为的,而Cx.皮皮恩斯Cx.五角星更动物性6。然而,在美国和世界许多其他地方,这些物种杂交,这对疾病传播有很强的影响,因为Cx.pipiens皮皮恩斯Cx.皮皮恩斯的杂交是机会型的喂食者,将咬鸟和人类9,从而成为西尼罗河病毒的桥梁载体。研究Culex蚊子生物学的这些和其他迷人的方面受到了阻碍,部分原因是Culex蚊子在实验室中饲养比伊蚊稍微困难一些,伊蚊产生静止和耐干燥的鸡蛋10,而且功能分子工具不如Culex物种开发得那么好。

CRISPR/Cas9基因组编辑是一项强大的技术,已用于评估几个重要的蚊子物种11,12,13生物学,包括南方房子蚊子,Culex五角星14,15,16。这项技术由詹妮弗·杜德纳和埃马努埃尔·夏彭蒂埃开发,利用细菌衍生的CRISPR相关内核糖(Cas蛋白:见范德奥斯特等人的评论)对病毒进行天然细菌防御。当注射到动物胚胎中时,Cas9蛋白质与适当的引导RNA结合,可以在基因组内产生双链断裂。这是最常通过使用Cas9蛋白质,这是复杂的指南RNA,引导内分泌酶活性到基因组的特定区域。在Cas9蛋白创造了一个特定于部位的双链断裂后,细胞机械试图使用两种机制之一来修复断裂。第一种需要通过非同源端连接(NHEJ)将两端连结在一起,这种连接容易出错,并且经常在基因组中产生框架外插入和缺失,从而产生非功能性蛋白质,从而产生淘汰突变。或者,蜂窝机械可能使用同源定向修复 (HDR), 通过查找类似的序列来正确修复中断。类似的序列可能由生物体内的第二条染色体提供(见审查18)。但是,如果修复的序列与原始序列完全匹配,Cas9 蛋白质将能够再次切割 DNA。或者,研究人员还可以包括一个供体质粒,该质粒包含目标序列切口两侧的同源序列,该序列通常带有荧光标记蛋白、原始基因的修改版本或其他可复制并插入基因组的修饰序列,或”敲击”。

注射胚胎时,时机至关重要,在使用CRISPR/Cas9基因组编辑在昆虫中产生突变时尤其如此。这是因为Cas9蛋白质和gRNA只有在胚胎处于同步状态、细胞膜形成之前以及胚胎内可获得多个细胞核时,才具有产生突变的最大能力。对于蚊子,核在卵泡后2-4小时到达外围,取决于温度19,因此必须在此时之前成功进行微喷射。此外,Cas9蛋白质将切断任何核DNA,它可以访问,这样,从注射产生的个体将包含细胞的马赛克,有些有所需的突变,而另一些没有。为了成功遗传这些突变,Cas9蛋白质必须切割存在于生殖系中的DNA,从而产生未来的卵子和精子。为了确保在生殖系中产生突变,最好将所有材料注射到靠近胚胎中极细胞位置的位置的地方,而胚胎是昆虫生殖系的祖细胞。极细胞位于 Culex 胚胎20的后端附近。除了注射胚胎外,还必须制定一个仔细的交叉和筛选后代的计划,以便检测所需的突变。

该协议描述了如何生成gRNA,并将其与Cas9蛋白复合,以准备注射混合物,以及如何诱导 Culex皮皮恩斯 雌性蚊子产卵,以及如何准备和注射这些卵子为CRISPR/Cas9介导的基因组编辑。此外,我们描述如何后方,交叉和屏幕注射胚胎及其后代,以确认所需的突变已经获得。使用这个协议,我们产生了一个感兴趣的基因, 周期,在 Culex皮皮恩斯的巴克耶菌株的空突变。这种菌株最初于2013年从俄亥俄州哥伦布市的野外采集蚊子中建立,由Meuti实验室维持。该协议可用于其他研究,要求CRISPR/Cas9基因组编辑在 Culex 蚊子,以及其他蚊子物种,更笼统地,是相关的使用CRISPR/Cas9基因组编辑到任何昆虫物种。

Protocol

在大多数研究机构中,在产生或维持转基因昆虫之前,必须制定经批准的《生物安全议定书》,以确保转基因生物不会逃逸或被从实验室设施中移走。政府的其他法规也可能适用。在开始这种性质的项目之前,检查所有机构政策和程序,以确定需要哪些文件和批准。 1. 设计 gRNA 和准备注射混合物 为每个目标基因设计 2-5 gRNA,因为某些 gRNA 比其他基因工作?…

Representative Results

使用上述协议,我们成功地注射了Cx.pipiens的胚胎,并观察到注射胚胎的存活率很高(+55%,图1)。早期的试验存活率较低,可能是因为卵泡前部附着在医用敷料条上,防止蚊子幼虫从胆汁中逸出并成功游入水中。确保前端延伸到医疗敷料条外,大大提高了幼虫的存活率,并导致高质量的后代,能够发展到成年和繁殖(图2B)。 <p class="jove_conten…

Discussion

该协议提出了将特定突变引入 Culex 蚊子基因组的方法,也可用于编辑其他蚊子的基因组。该协议意义重大,因为它不仅提供了如何准备注射材料的具体细节,而且还提供了如何诱导蚊子产卵以及如何准备和注射这些卵子的详细视频概述。我们还总结了如何利用雌性 Cx.pipiens 的生物学在单独的木筏上产卵,从而筛选出每个雌性子的较小比例的后代,以寻找所需的突变。这里提出的方法…

Disclosures

The authors have nothing to disclose.

Acknowledgements

我们感谢David O’Brochta博士和昆虫遗传技术协调研究网络的所有成员,感谢他们为我们和其他人提供的关于实施遗传技术的帮助和培训。我们特别感谢香娜·阿卢维哈雷优化了微操纵方案,允许 Culex 胚胎被注射和孵化。我们还要感谢在Meuti实验室工作的本科生德文特·西蒙斯和约瑟夫·乌尔索,感谢他们帮助照顾和筛查转基因蚊子,感谢ITF的佐拉·埃尔姆卡米协助饲养和准备蚊子注射。这项工作得到了奥苏传染病研究所向MEM提供的跨学科种子赠款的支持。

Materials

Artificial Membrane Feeder Hemotek SP5W1-3 Company location: Blackburn, UK
ATP Invitrogen 18330019 Company location: Carlsbad, CA, USA
Borosilicate glass mirocapillary tubes, 1 mm outer diameter World Precision Instruments 1B100-6 Company Location: Sarasota, FL, USA
BV10 Needle Beveler Sutter Instruments BV-10-B Company Location: Nobato, CA, USA
Whatman Circular filter paper (12.5 cm) Sigma Aldrich WHA1001125 Company Location: St. Louis, MO, USA
Conical tube (50 mL) Thermo Fisher Scientific 339652 Company Location: Waltham, MA, USA
Fisherbrand course filter paper with fast flow rate Thermo Fisher Scientific 09-800 Company Location: Waltham, MA, USA
Cover glass (24 x 40 mm) Thermo Fisher Scientific 50-311-20 Company Location: Waltham, MA, USA
Dental dam Henry Schein Inc 1010171 Company Location: Melville, NY USA
Scotch double-sided tape Thermo Fisher Scientific NC0879005 Company Location: Waltham, MA, USA
FemtoJet 4i microinjector Eppendorf 5252000021 Company Location: Hamburg, Germany
Glass vial (2 dram) Thermo Fisher Scientific 033401C Company Location: Waltham, MA, USA
Halocarbon oil Sigma Aldrich H8898-50ML Company Location: St. Louis, MO, USA
P-2000 Laser Needle Puller Sutter Instruments P-2000/G Company Location: Nobato, CA, USA
Parafilm Thermo Fisher Scientific 50-998-944 Company Location: Waltham, MA, USA
PC-100 Weighted Needle Puller Narishige PC-100 This is compatabile with the earlier PC-10 model, which has been discontinued. Company Location: Amityville, NY, USA
Phire Direct PCR Kit Thermo Fisher Scientific F140WH Company Location: Waltham, MA, USA
Kodak Photo-Flo (1%) Thermo Fisher Scientific 50-268-05 Company Location: Waltham, MA, USA
Quartz glass mirocapillary tubes, 1 mm outer diameter Capillary Tube Supplies Limited QGCT 1.0 Company Location: Cornwall, UK
Guide-it™ sgRNA Screening Kit Takara, Bio USA 632639 This kit allows you to determine if gRNAs cut DNA sequences in vitro. Company Location: Mountain View, CA, USA
Sigmacote Sigma Aldrich SL2-100ML Company Location: St. Louis, MO, USA
Small petri dishes (35X10 mm) Thermo Fisher Scientific 50-190-0273 Company Location: Waltham, MA, USA
Sodium citrate chicken blood Lampire biologicals 7201406 Company Location: Everett, PA, USA
Fisherbrand Square petri dish (10 cm x 10 cm) Thermo Fisher Scientific FB0875711A Company Location: Waltham, MA, USA
Tegaderm Henry Schein Inc. 7771180 Company Location: Melville, NY USA
Tropical fish food Tetramin N/A
Whatman filter paper Thermo Fisher Scientific 09-927-826 Company Location: Waltham, MA, USA
Whatman filter paper, 4.25 cm Sigma Aldrich 1001-042 Company Location: St. Louis, MO, USA

References

  1. Hamer, G. L., et al. Culex pipiens (Diptera: Culicidae): a bridge vector of West Nile virus to humans. Journal of Medical Entomology. 45 (1), 125-128 (2008).
  2. Bailey, C. L., et al. Isolation of St. Louis encephalitis virus from overwintering Culex pipiens mosquitoes. Science. 199 (4335), 1346-1349 (1978).
  3. Sabry, M. A new realistic index of experimental transmission efficiency for Bancroftian filariasis. The Journal of Tropical Medicine and Hygiene. 94 (4), 283-290 (1991).
  4. Cancrini, G., et al. Aedes albopictus and Culex pipiens implicated as natural vectors of Dirofilaria repens in central Italy. Journal of Medical Entomology. 44 (6), 1064-1066 (2007).
  5. Wilton, D. P., Smith, G. C. Ovarian diapause in three geographic strains of Culex pipiens (Diptera: Culicidae). Journal of Medical Entomology. 22 (5), 524-528 (1985).
  6. Mattingly, P. F. The Culex pipiens complex. Transactions of the Royal Entomological Society of London. 102 (7), 331-342 (1951).
  7. Eldridge, B. F. The effect of temperature and photoperiod on blood-feeding and ovarian development in mosquitoes of the Culex pipiens complex. The American Journal of Tropical Medicine and Hygiene. 17 (1), 133-140 (1968).
  8. Spielman, A., Wong, J. Environmental control of ovarian diapause in Culex pipiens. Annals of the Entomological Society of America. 66 (4), 905-907 (1973).
  9. Fritz, M. L., Walker, E. D., Miller, J. R., Severson, D. W., Dworkin, I. Divergent host preferences of above-and below-ground Culex pipiens mosquitoes and their hybrid offspring. Medical and Veterinary Entomology. 29 (2), 115-123 (2015).
  10. Meola, R. The influence of temperature and humidity on embryonic longevity in Aedes aegypti. Annals of the Entomological Society of America. 57 (4), 468-472 (1964).
  11. Dong, S., Lin, J., Held, N. L., Clem, R. J., Passarelli, A. L., Franz, A. W. Heritable CRISPR/Cas9-mediated genome editing in the yellow fever mosquito, Aedes aegypti. PloS one. 10 (3), (2015).
  12. Kyrou, K., et al. A CRISPR-Cas9 gene drive targeting doublesex causes complete population suppression in caged Anopheles gambiae mosquitoes. Nature Biotechnology. 36 (11), 1062-1066 (2018).
  13. Liu, T., et al. Construction of an efficient genomic editing system with CRISPR/Cas9 in the vector mosquito Aedes albopictus. Insect Science. 26 (6), 1045-1054 (2019).
  14. Itokawa, K., Komagata, O., Kasai, S., Ogawa, K., Tomita, T. Testing the causality between CYP9M10 and pyrethroid resistance using the TALEN and CRISPR/Cas9 technologies. Scientific Reports. 6, 24652 (2016).
  15. Li, M., Li, T., Liu, N., Raban, R. R., Wang, X., Akbari, O. S. Methods for the generation of heritable germline mutations in the disease vector Culex quinquefasciatus using clustered regularly interspaced short palindrome repeats-associated protein 9. Insect Molecular Biology. 29, 214-220 (2019).
  16. Anderson, M. E., et al. CRISPR/Cas9 gene editing in the West Nile Virus vector, Culex quinquefasciatus Say. PloS one. 14 (11), (2019).
  17. Van der Oost, J., Jore, M. M., Westra, E. R., Lundgren, M., Brouns, S. J. CRISPR-based adaptive and heritable immunity in prokaryotes. Trends in Biochemical Sciences. 34 (8), 401-407 (2009).
  18. Heyer, W. D., Ehmsen, K. T., Liu, J. Regulation of homologous recombination in eukaryotes. Annual Review of Genetics. 44, 113-139 (2010).
  19. Monnerat, A. T., et al. Anopheles albitarsis embryogenesis: morphological identification of major events. Memorias do Instituto Oswaldo Cruz. 97 (4), 589-596 (2002).
  20. Davis, C. W. C. A comparative study of larval embryogenesis in the mosquito Culex fatigans Wiedemann (Diptera: Culicidae) and the sheep-fly Lucilia sericata Meigen (Diptera: Calliphoridae). Australian Journal of Zoology. 15 (3), 547-579 (1967).
  21. Port, F., Chen, H. M., Lee, T., Bullock, S. L. Optimized CRISPR/Cas tools for efficient germline and somatic genome engineering in Drosophila. Proceedings of the National Academy of Sciences. 111 (29), 2967-2976 (2014).
  22. Kistler, K. E., Vosshall, L. B., Matthews, B. J. Genome engineering with CRISPR-Cas9 in the mosquito Aedes aegypti. Cell Reports. 11 (1), 51-60 (2015).
  23. Gokcezade, J., Sienski, G., Duchek, P. Efficient CRISPR/Cas9 plasmids for rapid and versatile genome editing in Drosophila. G3: Genes, Genomes, Genetics. 4 (11), 2279-2282 (2014).
  24. Hwang, W. Y., et al. Efficient in vivo genome editing using RNA-guided nucleases. Nature Biotechnology. 31 (3), 227-229 (2013).
  25. Basu, S., et al. Silencing of end-joining repair for efficient site-specific gene insertion after TALEN/CRISPR mutagenesis in Aedes aegypti. Proceedings of the National Academy of Sciences. 112 (13), 4038-4043 (2015).
  26. Hammond, A., et al. A CRISPR-Cas9 gene drive system targeting female reproduction in the malaria mosquito vector Anopheles gambiae. Nature Biotechnology. 34 (1), 78-83 (2016).
  27. Lin, S., Staahl, B. T., Alla, R. K., Doudna, J. A. Enhanced homology-directed human genome engineering by controlled timing of CRISPR/Cas9 delivery. eLife. 3, 04766 (2014).

Play Video

Cite This Article
Meuti, M. E., Harrell, R. Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9. J. Vis. Exp. (163), e61651, doi:10.3791/61651 (2020).

View Video