Is it cost effective to use CRISPR over MosTIC methods?
When using MosTIC and CRISPR for template-mediated gene insertion, the trade off is expense vs specificity. CRISPR reagents are higher in complexity. Unlike MosTIC, CRISPR transgenesis has more components. First, CRISPR requires a custom set of homology arms to be engineered for each cleavage site (not necessary in mosSCI because only a few loci are used for most insertions). Second, CRISPR requires a specific guide RNA to create Cas9 specificity for each site. Bottom line: there is more expense in the protocol for the end user when using CRISPR.
(CAVIAT: when deletions (MosDEL) and gene conversion (MosCON) are being considered, only the need guide RNA is the extra expense in CRISPR).
Is there a large number of sites that cannot be addressed by MosTIC methods?
Consider that about half of the CE genes have a nearby mos1 site (ex. 32 of the 58 known unc alleles (55%) have a mos1 within 1500 bp). When expanded to 5000 bp, the coverage jumps to 81% (ex 11/58 unc do not have mos1 within 5000bp). Yet getting MosDEL and MosCON on large segments suffers from low efficiency (many animals need to be injected just to get a chance at getting one, when deletions start targeting 10Kb or more). Bottom line: about 25 to 50% of the genome needing a CRISPR-like technology to get transgenesis done.