CRISPR‐Cas9 Genome Editing in Drosophila

Scott J. Gratz1, C. Dustin Rubinstein2, Melissa M. Harrison3, Jill Wildonger4, Kate M. O'Connor‐Giles5

1 Genetics Training Program, University of Wisconsin‐Madison, Madison, Wisconsin, 2 Laboratory of Cell and Molecular Biology, University of Wisconsin‐Madison, Madison, Wisconsin, 3 Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, 4 Department of Biochemistry, University of Wisconsin‐Madison, Madison, Wisconsin, 5 Corresponding author: Kate M. O'Connor‐Giles (
Publication Name:  Current Protocols in Molecular Biology
Unit Number:  Unit 31.2
DOI:  10.1002/0471142727.mb3102s111
Online Posting Date:  July, 2015
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The CRISPR‐Cas9 system has transformed genome engineering of model organisms from possible to practical. CRISPR‐Cas9 can be readily programmed to generate sequence‐specific double‐strand breaks that disrupt targeted loci when repaired by error‐prone non‐homologous end joining (NHEJ) or to catalyze precise genome modification through homology‐directed repair (HDR). Here we describe a streamlined approach for rapid and highly efficient engineering of the Drosophila genome via CRISPR‐Cas9‐mediated HDR. In this approach, transgenic flies expressing Cas9 are injected with plasmids to express guide RNAs (gRNAs) and positively marked donor templates. We detail target‐site selection; gRNA plasmid generation; donor template design and construction; and the generation, identification, and molecular confirmation of engineered lines. We also present alternative approaches and highlight key considerations for experimental design. The approach outlined here can be used to rapidly and reliably generate a variety of engineered modifications, including genomic deletions and replacements, precise sequence edits, and incorporation of protein tags. © 2015 by John Wiley & Sons, Inc.

Keywords: CRISPR; Cas9; homology directed repair; genome engineering; Drosophila

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Table of Contents

  • Introduction
  • Strategic Planning
  • Basic Protocol 1: Genome engineering of Drosophila via homology‐directed repair using the CRISPR‐Cas9 system
  • Alternate Protocol 1: HDR with Single‐Stranded DNA Donors
  • Alternate Protocol 2: HDR in Any Genetic Background
  • Alternate Protocol 3: Generation Of Disruptive Indels and Deletions VIA NHEJ
  • Reagents and Solutions
  • Commentary
  • Figures
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Basic Protocol 1: Genome engineering of Drosophila via homology‐directed repair using the CRISPR‐Cas9 system

  • vasa‐Cas9 fly stocks (Bloomington Drosophila Stock Center)
    • y1 M{vas‐Cas9.RFP‐}ZH‐2A w1118/FM7a, P{Tb1}FM7‐A (stock number 55821)
    • w1118; PBac{vas‐Cas9}VK00037/CyO, P{Tb1}CprCyO‐A (stock number 56552)
    • w1118; PBac{vas‐Cas9}VK00027 (stock number 51324)
  • Total DNA purification kit (DNeasy Blood and Tissue Kit; Qiagen)
  • PCR and sequencing primers (see unit 15.1; Kramer and Coen, )
  • Phusion High‐Fidelity DNA Polymerase (New England Biolabs)
  • Gel extraction kit (Wizard SV Gel and PCR Clean‐Up Sytem; Promega)
  • Pair of short complementary oligonucleotides for cloning each target site (see information under step 12)
  • Nuclease free H 2O
  • 10 U/μl T4 polynucleotide kinase (New England Biolabs)
  • 10× T4 DNA ligase buffer (New England Biolabs)
  • pU6‐BbsI‐gRNA (Addgene; plasmid 45946)
  • BbsI restriction endonuclease
  • 400 U/μl T4 DNA ligase (New England Biolabs)
  • E. coli DH5α or other suitable cloning strain
  • LB agar plates containing 100 μg/ml ampicillin (unit 1.1; Elbing and Brent, )
  • Plasmid miniprep kit (PureYield Plasmid Miniprep System; Promega)
  • Sequencing primers (also see unit 7.4; Slatko et al., ):
  • Endotoxin‐Free Plasmid Midi Kit (Macherey‐Nagel NucleoBond Xtra Midi EF or similar)
  • Primers to amplify both homology arms (see information under step 23)
  • pHD primers:
  • 10 mM dNTP mix: 10 mM each of dATP, dCTP, dGTP, and dTTP
  • 5× HF Phusion Buffer (New England Biolabs)
  • pHD‐DsRed‐attP (Addgene; Plasmid 51019, also called pDSRed‐attP)
  • pHD‐DsRed (Addgene; Plasmid 51434)
  • AarI restriction endonuclease
  • LB liquid medium containing 100 μg/ml ampicillin (unit 1.1; Elbing and Brent, )
  • Adult fly homogenization buffer (see Reagents and Solutions for recipe)
  • Proteinase K (New England Biolabs)
  • PCR and sequencing primers for identification and confirmation of CRISPR alleles (also see text under step 41):
    • Left‐Genomic‐F (target locus specific)
    • Right‐Genomic‐R (target locus specific)
  • Thermal cycler
  • 0.2‐ml PCR tubes
  • Additional reagents and equipment for the polymerase chain reaction (PCR; unit 15.1; Kramer and Coen, ), agarose gel electrophoresis (unit 2.5; Voytas, ), Sanger sequencing (unit 7.4; Slatko et al., ), determination of nucleic acid concentration by spectrophotometry ( appendix 3D; Gallagher, ), transformation of E. coli (unit 1.8; Seidman et al., ), and microinjection of Drosophila embryos (Dobson, )

Alternate Protocol 1: HDR with Single‐Stranded DNA Donors

  Additional Materials (also see protocol 1Basic Protocol)
  • ssDNA donor with homology arms (see text under step 1)

Alternate Protocol 2: HDR in Any Genetic Background

  Additional Materials (also see protocol 1Basic Protocol)
  • pBS‐Hsp70‐Cas9 plasmid (Addgene; plasmid 46294)

Alternate Protocol 3: Generation Of Disruptive Indels and Deletions VIA NHEJ

  Additional Materials (also see protocol 1Basic Protocol)
  • gRNAs for introducing a disruptive indel (see text under step 1)
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Internet Resources
  Bloomington Drosophila Stock Center CRISPR stocks.
  Addgene CRISPR plasmids.
Target finder tools
  CRISPR Optimal Target Finder.
  CRISPR Design.
Discussion groups!forum/flycrispr‐discussion‐group
  flyCRISPR discussion group.
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