Wir danken Dr. David O'Brochta und allen Mitgliedern des Insect Genetic Technologies Coordination Research Network für die Hilfe und Schulung, die sie uns und anderen bei der Implementierung genetischer Technologien bieten. Wir danken Channa Aluvihare besonders für die Optimierung des Mikromanipulationsprotokolls, damit Culex-Embryonen injiziert und geschlüpft werden können. Wir danken auch Devante Simmons und Joseph Urso, Studenten, die im Meuti-Labor arbeiten, für ihre Unterstützung bei der Pflege und dem Screening transgener Moskitos und Zora Elmkami von der ITF für die Unterstützung bei der Aufzucht und Vorbereitung von Moskitos für die Injektion. Diese Arbeit wurde durch ein Interdisciplinary Seeds Grant des Infectious Diseases Institute der OSU unterstützt, das MEM zur Verfügung gestellt wurde.

<ol>
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W., Dworkin, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Divergent+host+preferences+of+above-and+below-ground+Culex+pipiens+mosquitoes+and+their+hybrid+offspring.">Divergent host preferences of above-and below-ground Culex pipiens mosquitoes and their hybrid offspring.</a> Medical and Veterinary Entomology. 29 (2), 115-123 (2015).</li><li>Meola, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+temperature+and+humidity+on+embryonic+longevity+in+Aedes+aegypti.">The influence of temperature and humidity on embryonic longevity in Aedes aegypti.</a> Annals of the Entomological Society of America. 57 (4), 468-472 (1964).</li><li>Dong, S., Lin, J., Held, N. L., Clem, R. J., Passarelli, A. L., Franz, A. 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R., Wang, X., Akbari, O. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+the+generation+of+heritable+germline+mutations+in+the+disease+vector+Culex+quinquefasciatus+using+clustered+regularly+interspaced+short+palindrome+repeats-associated+protein+9.">Methods for the generation of heritable germline mutations in the disease vector Culex quinquefasciatus using clustered regularly interspaced short palindrome repeats-associated protein 9.</a> Insect Molecular Biology. 29, 214-220 (2019).</li><li>Anderson, M. E., 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=CRISPR/Cas9+gene+editing+in+the+West+Nile+Virus+vector,+Culex+quinquefasciatus+Say.">CRISPR/Cas9 gene editing in the West Nile Virus vector, Culex quinquefasciatus Say.</a> PloS one. 14 (11), (2019).</li><li>Van der Oost, J., Jore, M. M., Westra, E. R., Lundgren, M., Brouns, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR-based+adaptive+and+heritable+immunity+in+prokaryotes.">CRISPR-based adaptive and heritable immunity in prokaryotes.</a> Trends in Biochemical Sciences. 34 (8), 401-407 (2009).</li><li>Heyer, W. D., Ehmsen, K. T., Liu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+homologous+recombination+in+eukaryotes.">Regulation of homologous recombination in eukaryotes.</a> Annual Review of Genetics. 44, 113-139 (2010).</li><li>Monnerat, A. T., 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=Anopheles+albitarsis+embryogenesis:+morphological+identification+of+major+events.">Anopheles albitarsis embryogenesis: morphological identification of major events.</a> Memorias do Instituto Oswaldo Cruz. 97 (4), 589-596 (2002).</li><li>Davis, C. W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+study+of+larval+embryogenesis+in+the+mosquito+Culex+fatigans+Wiedemann+(Diptera:+Culicidae)+and+the+sheep-fly+Lucilia+sericata+Meigen+(Diptera:+Calliphoridae).">A comparative study of larval embryogenesis in the mosquito Culex fatigans Wiedemann (Diptera: Culicidae) and the sheep-fly Lucilia sericata Meigen (Diptera: Calliphoridae).</a> Australian Journal of Zoology. 15 (3), 547-579 (1967).</li><li>Port, F., Chen, H. M., Lee, T., Bullock, S. 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RH arbeitet für die Insect Transformation Facility, die Dienstleistungen in der genetischen Veränderung von Insekten anbietet.

Dieses Protokoll stellt Methoden vor, um spezifische Mutationen in das Genom von Culex-Moskitos einzuführen und kann verwendet werden, um auch das Genom anderer Moskitos zu bearbeiten. Das Protokoll ist insoweit von Bedeutung, als es nicht nur spezifische Details zur Vorbereitung der Injektionsmaterialien enthält, sondern auch einen detaillierten Videoüberblick darüber, wie Moskitos dazu veranlasst werden, Eier zu legen, sowie wie diese Eier zubereitet und injiziert werden. Wir fassen auch zusammen, wie man...

Culex-Moskitos sind in den gemäßigten und tropischen Regionen der Welt verbreitet und übertragen mehrere tödliche Viren, darunter West-Nil-Virus1,St. Louis-Enzephalitis2 sowie filariale Nematoden, die Hundeherzwurm3 und Elephantiasis4verursachen. Mitglieder des Culex pipiens-Komplexes, zu dem Cx. quinquefasciatus, Cx. pipiens pipiens und Cx. pipiens molestusgehören , zeigen auffällige Variationen in vielen Aspekten ihrer Biologie. Zum Beispiel, während Cx. quinquefasciatus und Cx. pipiens molestus nicht in der Lage sind, in eine überwinternde Ruhephase5,6, Cx. pipiens pipiens zeigen robuste saisonale Reaktionen und treten in die Diapause als Reaktion auf kurze Tage7,8ein. Darüber hinaus neigen Cx. pipiens molestus dazu, anthropophiler zu sein, während Cx. pipiens und Cx. quinquefasciatus zoophiler sind6. In den Vereinigten Staaten und an vielen anderen Orten der Welt kreuzen sich diese Arten jedoch, was starke Auswirkungen auf die Krankheitsübertragung hat, da Hybriden der Cx. pipiens pipiens und Cx. pipiens molestus opportunistische Feeder sind und sowohl Vögel als auch Menschenbeißen 9und somit als Brückenvektoren für das West-Nil-Virus dienen. Das Studium dieser und anderer faszinierender Aspekte der Biologie von Culex-Moskitos wurde zum Teil behindert, weil Culex-Moskitos im Labor etwas schwieriger zu züchten sind als Aedes-Moskitos, die ruhe- und austrocknungsresistente Eier produzieren10 und weil funktionelle molekulare Werkzeuge für Culex-Arten nicht so gut entwickelt sind.
CRISPR / Cas9 Genom-Editing ist eine leistungsstarke Technologie, die verwendet wurde, um die Biologie mehrerer wichtiger Mückenarten11,12,13, einschließlich der Südlichen Hausmücke, Culex quinquefasciatus14,15,16. Diese von Jennifer Doudna und Emmanuelle Charpentier entwickelte Technologie nutzt eine natürliche bakterielle Abwehr gegen Viren durch bakteriell abgeleitete, CRISPR-assoziierte Endonukleasen (Cas-Proteine; siehe Review von Van der Oost et al.17). Bei der Injektion in tierische Embryonen können die Cas9-Proteine in Kombination mit einer geeigneten Leit-RNA doppelsträngige Brüche im Genom erzeugen. Dies geschieht am häufigsten durch die Verwendung des Cas9-Proteins, das mit Leit-RNAs komplexiert ist, die die Endonukleaseaktivität auf eine bestimmte Region des Genoms lenken. Nachdem das Cas9-Protein einen ortsspezifischen Doppelstrangbruch erzeugt hat, versucht die zelluläre Maschinerie, den Bruch mit einem von zwei Mechanismen zu reparieren. Die erste beinhaltet die Ligatur der beiden Enden durch nicht-homologe End-Joining (NHEJ), die fehleranfällig ist und oft Out-Frame-Insertionen und Deletionen im Genom erzeugt, die zu nicht-funktionellen Proteinen führen können, wodurch eine Knock-out-Mutation erzeugt wird. Alternativ kann die zelluläre Maschinerie die homologiegerichtete Reparatur (HDR) verwenden, indem sie ähnliche Sequenzen findet, um den Bruch korrekt zu reparieren. Die ähnliche Sequenz kann durch das zweite Chromosom im Organismus bereitgestellt werden (siehe Review18). Wenn die reparierte Sequenz jedoch genau mit der ursprünglichen Sequenz übereinstimmt, kann das Cas9-Protein die DNA erneut schneiden. Alternativ können Forscher auch ein Spenderplasmid einschließen, das homologe Sequenzen auf beiden Seiten der Schnittstelle der Zielsequenz mit einer alternativen Reparatursequenz enthält - oft ein fluoreszierendes Markerprotein, eine modifizierte Version des ursprünglichen Gens oder eine andere Modifikation -, die kopiert und in das Genom eingefügt oder "eingeklopft" werden kann.
Das Timing ist bei der Injektion von Embryonen entscheidend, und dies ist insbesondere der Fall, wenn CRISPR / Cas9-Genom-Editing verwendet wird, um Mutationen bei Insekten zu erzeugen. Dies liegt daran, dass das Cas9-Protein und gRNAs die größte Fähigkeit haben, Mutationen nur dann zu erzeugen, wenn sich der Embryo in seinem synzytialen Zustand befindet, bevor sich Zellmembranen gebildet haben und wenn mehrere Kerne im Embryo zugänglich sind. Bei Moskitos erreichen die Kerne die Peripherie ~ 2-4 Stunden nach der Eiablage, abhängig von der Temperatur19, und daher muss vor dieser Zeit eine erfolgreiche Mikroinjektion erfolgen. Darüber hinaus schneidet das Cas9-Protein jede Kern-DNA, auf die es zugreifen kann, so dass das Individuum, das aus der Injektion resultiert, ein Mosaik von Zellen enthält, von denen einige die gewünschte Mutation aufweisen und andere nicht. Damit diese Mutationen erfolgreich vererbt werden können, muss das Cas9-Protein DNA schneiden, die sich in der Keimbahn befindet und die zukünftigen Eier und Spermien hervorbringt. Um sicherzustellen, dass Mutationen in der Keimbahn erzeugt werden, ist es am besten, alle Materialien in der Nähe der Position der Polzellen im Embryo zu injizieren, die die Vorläufer der Insektenkeimbahn sind. Die Polzellen befinden sich in der Nähe des hinteren Endes der Culex-Embryonen 20. Neben der Injektion von Embryonen ist es unerlässlich, einen sorgfältigen Plan für die Kreuzung und das Screening von Nachkommen zu entwickeln, um die gewünschte Mutation zu erkennen.
Dieses Protokoll beschreibt, wie gRNAs erzeugt und mit Cas9-Protein komplexiert werden, um Injektionsmischungen herzustellen, sowie wie weibliche Moskitos von Culex pipiens dazu veranlasst werden, Eier zu legen und wie diese Eier für die CRISPR / Cas9-vermittelte Genombearbeitung vorbereitet und injiziert werden. Darüber hinaus beschreiben wir, wie injizierte Embryonen und ihre Nachkommen aufgezogen, gekreuzt und gescreent werden, um zu bestätigen, dass die gewünschte Mutation erhalten wurde. Mit diesem Protokoll generierten wir Nullmutationen für ein Gen von Interesse, Zyklus,im Buckeye-Stamm von Culex pipiens. Dieser Stamm wurde ursprünglich 2013 aus feldgesammelten Moskitos in Columbus, Ohio, entwickelt und wird vom Meuti-Labor gepflegt. Dieses Protokoll kann für zusätzliche Studien verwendet werden, die eine CRISPR/Cas9-Genombearbeitung bei Culex-Moskitos sowie anderen Mückenarten erfordern, und ist im Allgemeinen für die Verwendung von CRISPR/Cas9-Genom-Editing bei jeder Insektenart relevant.

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

preparing and injecting embryos of culex mosquitoes to generate null mutations using crispr/cas9

Culex-Moskitos sind die Hauptvektoren mehrerer Krankheiten, die sich negativ auf die Gesundheit von Mensch und Tier auswirken, einschließlich west-Nil-Virus und Krankheiten, die durch filariale Nematoden wie Hundeherzwurm und Elefantenasis verursacht werden. Vor kurzem wurde CRISPR / Cas9-Genom-Editing verwendet, um ortsgerichtete Mutationen zu induzieren, indem ein Cas9-Protein, das mit einer Leit-RNA (gRNA) komplexiert wurde, in frisch gelegte Embryonen mehrerer Insektenarten injiziert wurde, einschließlich Moskitos, die zu den Gattungen Anopheles und Aedesgehören. Die Manipulation und Injektion von Culex-Moskitos ist etwas schwieriger, da diese Moskitos ihre Eier aufrecht in Flößen ablegen und nicht einzeln wie andere Mückenarten. Hier beschreiben wir, wie man gRNAs entwirft, sie mit Cas9-Protein komplexiert, weibliche Moskitos von Culex pipiens dazu bringt, Eier zu legen, und wie man neu gelegte Embryonen für die Mikroinjektion mit Cas9 / gRNA vorbereitet und injiziert. Wir beschreiben auch, wie man injizierte Moskitos auf die gewünschte Mutation rückt und abschirmt. Die repräsentativen Ergebnisse zeigen, dass diese Technik verwendet werden kann, um ortsgerichtete Mutationen im Genom von Culex-Moskitos zu induzieren und mit leichten Modifikationen auch bei anderen Mückenarten Nullmutanten zu erzeugen.

Mit dem beschriebenen Protokoll konnten wir erfolgreich Embryonen von Cx. pipiensinjizieren und beobachteten eine hohe Überlebensrate unter den injizierten Embryonen (~ 55%, Abbildung 1). Frühere Studien hatten einen geringeren Prozentsatz des Überlebens, wahrscheinlich, weil der vordere Teil des Eifollikels am medizinischen Verbandsstreifen befestigt war, was verhinderte, dass Mückenlarven aus dem Chorion entweichen und erfolgreich ins Wasser schwammen. Die Sicherstellung, dass...

Watch this Scientific Journal Video about Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9 at JoVE.com

Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9

CRISPR/Cas9 wird zunehmend zur Charakterisierung der Genfunktion in Nicht-Modellorganismen eingesetzt. Dieses Protokoll beschreibt, wie Man Knock-out-Linien von Culex pipienserzeugt, von der Vorbereitung von Injektionsmischungen über die Gewinnung und Injektion von Moskitoembryonen bis hin zur Aufzucht, Kreuzung und dem Screening injizierter Moskitos und ihrer Nachkommen auf gewünschte Mutationen.

Vorbereitung und Injektion von Embryonen von Culex-Moskitos zur Erzeugung von Nullmutationen mit CRISPR/Cas9

Culex mosquitoes are the major vectors of several diseases that negatively impact human and animal health including West Nile virus and diseases caused by ...

preparing-injecting-embryos-culex-mosquitoes-to-generate-null

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9

6.8K Aufrufe.  The Ohio State University. CRISPR/Cas9 wird zunehmend zur Charakterisierung der Genfunktion in Nicht-Modellorganismen eingesetzt. Dieses Protokoll beschreibt, wie Man Knock-out-Linien von Culex pipienserzeugt, von der Vorbereitung von Injektionsmischungen über die Gewinnung und Injektion von Moskitoembryonen bis hin zur Aufzucht, Kreuzung und dem Screening injizierter Moskitos und ihrer Nachkommen auf gewünschte Mutationen.

Serie: Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9

Using a Fluorescent PCR-capillary Gel Electrophoresis Technique to Genotype CRISPR/Cas9-mediated Knockout Mutants in a High-throughput Format

The development of programmable genome-editing tools has facilitated the use of reverse genetics to understand the roles specific genomic sequences play in the functioning of cells and whole organisms. This cause has been tremendously aided by the recent introduction of the CRISPR/Cas9 system-a versatile tool that allows researchers to manipulate the genome and transcriptome in order to, among other things, knock out, knock down, or knock in genes in a targeted manner. For the purpose of knocking out a gene, CRISPR/Cas9-mediated double-strand breaks recruit the non-homologous end-joining DNA repair pathway to introduce the frameshift-causing insertion or deletion of nucleotides at the break site. However, an individual guide RNA may cause undesirable off-target effects, and to rule these out, the use of multiple guide RNAs is necessary. This multiplicity of targets also means that a high-volume screening of clones is required, which in turn begs the use of an efficient high-throughput technique to genotype the knockout clones. Current genotyping techniques either suffer from inherent limitations or incur high cost, hence rendering them unsuitable for high-throughput purposes. Here, we detail the protocol for using fluorescent PCR, which uses genomic DNA from crude cell lysate as a template, and then resolving the PCR fragments via capillary gel electrophoresis. This technique is accurate enough to differentiate one base-pair difference between fragments and hence is adequate in indicating the presence or absence of a frameshift in the coding sequence of the targeted gene. This precise knowledge effectively precludes the need for a confirmatory sequencing step and allows users to save time and cost in the process. Moreover, this technique has proven to be versatile in genotyping various mammalian cells of various tissue origins targeted by guide RNAs against numerous genes, as shown here and elsewhere.

The genotyping technique described here, which couples fluorescent polymerase chain reaction (PCR) to capillary gel electrophoresis, allows for high-throughput genotyping of nuclease-mediated knockout clones. It circumvents limitations faced by other genotyping techniques and is more cost effective than sequencing methods.

Mit Hilfe eines Fluoreszenz-PCR-Kapillar-Gel-Elektrophorese-Technik CRISPR zum Genotyp / Cas9 vermittelte Knock-out Mutanten in einem Hochdurchsatz-Format

The development of programmable genome-editing tools has facilitated the use of reverse genetics to understand the roles specific genomic sequences play ...

Forschung

Genetik

A Rapid and Facile Pipeline for Generating Genomic Point Mutants in C. elegans Using CRISPR/Cas9 Ribonucleoproteins

The clustered regularly interspersed palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) prokaryotic adaptive immune defense system has been co-opted as a powerful tool for precise eukaryotic genome engineering. Here, we present a rapid and simple method using chimeric single guide RNAs (sgRNA) and CRISPR-Cas9 Ribonucleoproteins (RNPs) for the efficient and precise generation of genomic point mutations in C. elegans. We describe a pipeline for sgRNA target selection, homology-directed repair (HDR) template design, CRISPR-Cas9-RNP complexing and delivery, and a genotyping strategy that enables the robust and rapid identification of correctly edited animals. Our approach not only permits the facile generation and identification of desired genomic point mutant animals, but also facilitates the detection of other complex indel alleles in approximately 4 - 5 days with high efficiency and a reduced screening workload.

A Rapid and Facile Pipeline for Generating Genomic Point Mutants in C. elegans Using CRISPR/Cas9 Ribonucleoproteins

Here, we present a method to engineer the genome of C. elegans using CRISPR-Cas9 ribonucleoproteins and homology dependent repair templates.

Eine schnelle und Facile Pipeline für die Erzeugung von Genomic Punkt Mutanten in C. Elegans verwenden CRISPR/Cas9 Ribonucleoproteins

The clustered regularly interspersed palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) prokaryotic adaptive immune defense system has been ...

Generation of Defined Genomic Modifications Using CRISPR-CAS9 in Human Pluripotent Stem Cells

Human pluripotent stem cells offer a powerful system to study gene function and model specific mutations relevant to disease. The generation of precise heterozygous genetic modifications is challenging due to CRISPR-CAS9 mediated indel formation in the second allele. Here, we demonstrate a protocol to help overcome this difficulty by using two repair templates in which only one expresses the desired sequence change, while both templates contain silent mutations to prevent re-cutting and indel formation. This methodology is most advantageous for gene editing coding regions of DNA to generate isogenic control and mutant human stem cell lines for studying human disease and biology. In addition, optimization of transfection and screening methodologies have been performed to reduce labor and cost of a gene editing experiment. Overall, this protocol is widely applicable to many genome editing projects utilizing the human pluripotent stem cell model.

This protocol provides a method to facilitate the generation of defined heterozygous or homozygous nucleotide changes using CRISPR-CAS9 in human pluripotent stem cells.

Generierung definierter genomischer Modifikationen mit CRISPR-CAS9 in humanen pluripotenten Stammzellen

Human pluripotent stem cells offer a powerful system to study gene function and model specific mutations relevant to disease. The generation of precise ...

Embryo Microinjection Techniques for Efficient Site-Specific Mutagenesis in Culex quinquefasciatus

Culex quinquefasciatus is a vector of a diverse range of vector-borne diseases such as avian malaria, West Nile virus (WNV), Japanese encephalitis, Eastern equine encephalitis, lymphatic filariasis, and Saint Louis encephalitis. Notably, avian malaria has played a major role in the extinction of numerous endemic island bird species, while WNV has become an important vector-borne disease in the United States. To gain further insight into C. quinquefasciatus biology and expand their genetic control toolbox, we need to develop more efficient and affordable methods for genome engineering in this species. However, some biological traits unique to Culex mosquitoes, particularly their egg rafts, have made it difficult to perform microinjection procedures required for genome engineering. To address these challenges, we have developed an optimized embryo microinjection protocol that focuses on mitigating the technical obstacles associated with the unique characteristics of Culex mosquitoes. These procedures demonstrate optimized methods for egg collection, egg raft separation and other handling procedures essential for successful microinjection in C. quinquefasciatus. When coupled with the CRISPR/Cas9 genome editing technology, these procedures allow us to achieve site-specific, efficient and heritable germline mutations, which are required to perform advanced genome engineering and develop genetic control technologies in this important, but currently understudied, disease vector.

Embryo Microinjection Techniques for Efficient Site-Specific Mutagenesis in Culex quinquefasciatus

This protocol describes microinjection procedures for Culex quinquefasciatus embryos that are optimized to work with CRISPR/Cas9 gene editing tools. This technique can efficiently generate site-specific, heritable, germline mutations that can be used for building genetic technologies in this understudied disease vector.

Embryo-Mikroinjektionstechniken für eine effiziente ortsspezifische Mutagenese bei Culex quinquefasciatus

Culex quinquefasciatus is a vector of a diverse range of vector-borne diseases such as avian malaria, West Nile virus (WNV), Japanese encephalitis, ...

Sand Fly (Phlebotomus papatasi) Embryo Microinjection for CRISPR/Cas9 Mutagenesis

Sand flies are the natural vectors for Leishmania species, protozoan parasites producing a broad spectrum of symptoms ranging from cutaneous lesions to visceral pathology. Deciphering the nature of the vector/parasite interactions is of primary importance for better understanding of Leishmania transmission to their hosts. Among the parameters controlling the sand fly vector competence (i.e. their ability to carry and transmit pathogens), parameters intrinsic to these insects were shown to play a key role. Insect immune response, for example, impacts sand fly vector competence to Leishmania. The study of such parameters has been limited by the lack of methods of gene expression modification adapted for use in these non-model organisms. Gene downregulation by small interfering RNA (siRNA) is possible, but in addition to being technically challenging, the silencing leads to only a partial loss of function, which cannot be transmitted from generation to generation. Targeted mutagenesis by CRISPR/Cas9 technology was recently adapted to the Phlebotomus papatasi sand fly. This technique leads to the generation of transmissible mutations in a specifically chosen locus, allowing to study the genes of interest. The CRISPR/Cas9 system relies on the induction of targeted double-strand DNA breaks, later repaired by either Non-Homologous End Joining (NHEJ) or by Homology Driven Repair (HDR). NHEJ consists of a simple closure of the break and frequently leads to small insertion/deletion events. In contrast, HDR uses the presence of a donor DNA molecule sharing homology with the target DNA as a template for repair. Here, we present a sand fly embryo microinjection method for targeted mutagenesis by CRISPR/Cas9 using NHEJ, which is the only genome modification technique adapted to sand fly vectors to date.

Sand Fly Phlebotomus papatasi Embryo Microinjection for CRISPR/Cas9 Mutagenesis

This protocol details the steps of CRISPR/Cas9 targeted mutagenesis in sand flies: embryo collection, injection, insect rearing, and identification as well as selection of mutations of interest.

Sandfliege (Phlebotomus papatasi) Embryo Mikroinjektion für CRISPR/Cas9 Mutagenese

Sand flies are the natural vectors for Leishmania species, protozoan parasites producing a broad spectrum of symptoms ranging from cutaneous lesions to ...

Small-Cage Laboratory Trials of Genetically-Engineered Anopheline Mosquitoes

Control of mosquito-borne pathogens using genetically-modified vectors has been proposed as a promising tool to complement conventional control strategies. CRISPR-based homing gene drive systems have made transgenic technologies more accessible within the scientific community. Evaluation of transgenic mosquito performance and comparisons with wild-type counterparts in small laboratory cage trials provide valuable data for the design of subsequent field cage experiments and experimental assessments to refine the strategies for disease prevention. Here, we present three different protocols used in laboratory settings to evaluate transgene spread in anopheline mosquito vectors of malaria. These include inundative releases (no gene-drive system), and gene-drive overlapping and non-overlapping generation trials. The three trials vary in a number of parameters and can be adapted to desired experimental settings. Moreover, insectary studies in small cages are part of the progressive transition of engineered insects from the laboratory to open field releases. Therefore, the protocols described here represent invaluable tools to provide empirical values that will ultimately aid field implementation of new technologies for malaria elimination.

The protocols reported here illustrate three alternative ways to assess the performance of genetically-engineered mosquitoes destined for vector control in laboratory-contained small cage trials. Each protocol is tailored to the specific modification the mosquito strain bears (gene drive or non-gene drive) and the types of parameters measured.

Kleinkäfig-Laborversuche mit gentechnisch veränderten Anopheline-Mücken

Control of mosquito-borne pathogens using genetically-modified vectors has been proposed as a promising tool to complement conventional control ...

Digital-Droplet PCR to Detect Indels Mutations in Genetically Modified Anopheline Mosquito Populations

Recent advances in mosquito genomics and genetic engineering technologies have fostered a need for quick and efficient methods for detecting targeted DNA sequence variation on a large scale. Specifically, detecting insertions and deletions (indels) at gene-edited sites generated by CRISPR guide RNA (gRNA)/Cas9-mediated non-homologous end-joining (NHEJ) is important for assessing the fidelity of the mutagenesis and the frequency of unintended changes. We describe here a protocol for digital-droplet PCR (ddPCR) that is well-suited for high-throughput NHEJ analysis. While this method does not produce data that identifies individual sequence variation, it provides a quantitative estimate of the sequence variation within a population. Additionally, with appropriate resources, this protocol can be implemented in a field-site laboratory setting more easily than next-generation or Sanger sequencing. ddPCR also has a faster turn-around time for results than either of those methods, which allows a more quick and complete analysis of genetic variation in wild populations during field trials of genetically-engineered organisms.

This protocol provides the steps from DNA extraction to experimental set-up for digital droplet PCR (ddPCR), including analysis for the identification and quantification of non-homologous end-joining (NHEJ) events at target sites following gRNA-induced Cas9 cleavage and DNA repair. Other uses of this method include applications such as polymorphism detection and gene-editing variant verification.

Digital-Droplet PCR zum Nachweis von Indel-Mutationen in gentechnisch veränderten Anopheline-Mückenpopulationen

Recent advances in mosquito genomics and genetic engineering technologies have fostered a need for quick and efficient methods for detecting targeted DNA ...

Indel Detection following CRISPR/Cas9 Mutagenesis using High-resolution Melt Analysis in the Mosquito Aedes aegypti

Mosquito gene editing has become routine in several laboratories with the establishment of systems such as transcription-activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs), and homing endonucleases (HEs). More recently, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology has offered an easier and cheaper alternative for precision genome engineering. Following nuclease action, DNA repair pathways will fix the broken DNA ends, often introducing indels. These out-of-frame mutations are then used for understanding gene function in the target organisms. A drawback, however, is that mutant individuals carry no dominant marker, making identification and tracking of mutant alleles challenging, especially at scales needed for many experiments. 
High-resolution melt analysis (HRMA) is a simple method to identify variations in nucleic acid sequences and utilizes PCR melting curves to detect such variations. This post-PCR analysis method uses fluorescent double-stranded DNA-binding dyes with instrumentation that has temperature ramp control data capture capability and is easily scaled to 96-well plate formats. Described here is a simple workflow using HRMA for the rapid detection of CRISPR/Cas9-induced indels and the establishment of mutant lines in the mosquito Ae. aegypti. Critically, all steps can be performed with a small amount of leg tissue and do not require sacrificing the organism, allowing genetic crosses or phenotyping assays to be performed after genotyping.

Indel Detection following CRISPR/Cas9 Mutagenesis using High-resolution Melt Analysis in the Mosquito Aedes aegypti

This article details a protocol for rapid identification of indels induced by CRISPR/Cas9 and selection of mutant lines in the mosquito Aedes aegypti using high-resolution melt analysis.

Indel-Nachweis nach CRISPR/Cas9-Mutagenese mittels hochauflösender Schmelzeanalyse in der Mücke Aedes aegypti

Mosquito gene editing has become routine in several laboratories with the establishment of systems such as transcription-activator-like effector nucleases ...

Genome Editing in the Yellow Fever Mosquito Aedes aegypti using CRISPR-Cas9

The emergence of the clustered, regularly interspersed, short palindromic repeats (CRISPR)-Cas9 technology has revolutionized the genetic engineering field and opened the doors for precise genome editing in multiple species, including non-model organisms. In the mosquito Aedes aegypti, loss-of-function mutations and DNA insertions have been accomplished with this technology. Here, we describe a detailed protocol for genome editing through embryonic microinjection in the mosquito A. aegypti using the CRISPR-Cas9 technology, focusing on both the generation of gene knockout and knockin lines. In this protocol, quartz needles are filled with a mixture of guide RNA, recombinant Cas9, and a plasmid containing a DNA cassette encoding a gene for a fluorescent marker, if gene knockin is desired. Embryos at the preblastoderm stage are lined up onto a strip of double-sided sticky tape placed onto a coverslip, which is subsequently mounted onto a glass slide. With the help of a microinjector, the needles are inserted gently into the posterior end of the embryos and a small volume of the CRISPR mixture is dispensed. When the embryos are hatched, the larvae are checked under the fluorescent scope, and the pupae are sex-sorted and separated in different cages. Once the adults emerge, these are reciprocally crossed with wild-type individuals, blood-fed, and placed for egg laying. Once these eggs are hatched, the fluorescent larvae collected represent individuals with stable insertion of the DNA cassette into their genome. These larvae are then grown to the adult stage, outcrossed to wild-type individuals, and then further assessed through molecular techniques to confirm that the exact sequence of the DNA cassette is present at the desired site of the mosquito genome. Homozygous lines can also be obtained by following the provided pipeline of crossing schema and molecular screening of the mutations.

Here, we describe a detailed protocol for genome editing through embryonic microinjection in the mosquito A. aegypti using the CRISPR-Cas9 technology.

Genome Editing bei der Gelbfiebermücke Aedes aegypti mittels CRISPR-Cas9

The emergence of the clustered, regularly interspersed, short palindromic repeats (CRISPR)-Cas9 technology has revolutionized the genetic engineering ...

Construction of Homozygous Mutants of Migratory Locust Using CRISPR/Cas9 Technology

The migratory locust, Locusta migratoria, is not only one of the worldwide plague locusts that caused huge economic losses to human beings but also an important research model for insect metamorphosis. The CRISPR/Cas9 system can accurately locate at a specific DNA locus and cleave within the target site, efficiently introducing double-strand breaks to induce target gene knockout or integrate new gene fragments into the specific locus. CRISPR/Cas9-mediated genome editing is a powerful tool for addressing questions encountered in locust research as well as a promising technology for locust control. This study provides a systematic protocol for CRISPR/Cas9-mediated gene knockout with the complex of Cas9 protein and single guide RNAs (sgRNAs) in migratory locusts. The selection of target sites and design of sgRNA are described in detail, followed by in vitro synthesis and verification of the sgRNAs. Subsequent procedures include egg raft collection and tanned-egg separation to achieve successful microinjection with low mortality rate, egg culture,&#160;preliminary estimation of the mutation rate, locust breeding as well as detection, preservation, and passage of the mutants to ensure population stability of the edited locusts. This method can be used as a reference for CRISPR/Cas9 based gene editing applications in migratory locusts as well as in other insects.

This study provides a systematically optimized procedure of CRISPR/Cas9 ribonuclease-based construction of homozygous locust mutants as well as a detailed method for cryopreservation and resuscitation of the locust eggs.

Konstruktion homozygoter Mutanten der Wanderheuschrecke mittels CRISPR/Cas9-Technologie

The migratory locust, Locusta migratoria, is not only one of the worldwide plague locusts that caused huge economic losses to human beings but also an ...