Table 2 Comparison of MCR and CRISPR-it technology
Mutagenic chain reactionCRISPR-it
Work environmentStrict physical containment:Regular fly room and working procedures* (*suitable for work with standard transgenic organisms)
 Triple contained flies
 Locked facilities at all times
 Accounting for individual flies
 Single experimenter
CRISPR componentsOn one constructSeparate, integrated transgenes
Directly reveals recessive phenotypesYes (so far shown for a single target site)Yes (shown for many target sites)
Efficiency of germline transmission of mutationsUp to 100%Up to 100%
CRISPR inactivated by crossingNoYes
Risk of infiltrating wild and laboratory populationsYesNo
Genotype at target siteMosaic in all generations (mostly homozygous for MCR allele)F1: Mosaic (mostly biallelic for indels)
F2: heterozygous
F3: homozygous
Time from cloning to recessive phenotype∼25 d∼36 db
Targeting essential genesNocYes
Tissue-specific mutagenesisNoYes
  • MCR, mutagenic chain reaction; CRISPR-it, Clustered Regularly Interspaced Short Palindromic Repeat with independent transgenes.

  • a Generation of multiple gRNA plasmids can be multiplexed during cloning and transgenesis. Multiplexing is not possible during MCR.

  • b One additional generation.

  • c Targeting of essential genes might be possible in the future by introducing an MCR resistant rescue construct into the MCR cassette (Gantz and Bier 2015).