| Mutagenic chain reaction | CRISPR-it | |
|---|---|---|
| Work environment | Strict 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 components | On one construct | Separate, integrated transgenes |
| Multiplexinga | No | Yes |
| Directly reveals recessive phenotypes | Yes (so far shown for a single target site) | Yes (shown for many target sites) |
| Efficiency of germline transmission of mutations | Up to 100% | Up to 100% |
| CRISPR inactivated by crossing | No | Yes |
| Risk of infiltrating wild and laboratory populations | Yes | No |
| Genotype at target site | Mosaic 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 genes | Noc | Yes |
| Tissue-specific mutagenesis | No | Yes |
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).