CLICK: one-step generation of conditional knockout mice

Table 1 CRISPR/Cas-mediated insertion of loxP sequences at targeted sites in mice and rats

Species	Strain	Target gene	lssDNA size (bp)	Transfer method	Embryos injected (n)	Embryos transferred (%)	Live births (%)	F0 animals
Species	Strain	Target gene	lssDNA size (bp)	Transfer method	Embryos injected (n)	Embryos transferred (%)	Live births (%)	LD (%)	loxP (%)	flox (%)	Conditional (%)
Mouse	C57B6	Serpina3n	708	MI	371	255 (68.7)	56 (22.0)	28 (50.0)	7 (12.5)	9 (16.1)	5 (8.9)
	C57B6	Tyr	892	MI	222	149 (67.1)	17 (11.4)	2 (11.8)	4 (23.5)	3 (17.6)	–
	C57B6	mKIAA1322	1429	MI	166	134 (80.7)	5 (3.7)	1 (20.0)	–	4 (80.0)	2 (40.0)
	C57B6	Serpina3n	708	EL	180	160 (88.9)	18 (11.3)	9 (50.0)	2 (11.1)	2 (11.1)	2^b (11.1)
	C57B6	Mct4	1095	EL	134	130 (97.0)	21 (16.2)	11 (52.4)	3 (14.3)	2 (9.5)	1 (4.7)
Rat	F344	Vapb	674	EL	160	77 (48.1)	6 (7.8)	2 (33.3)	1 (16.6)	3^a (50.0)	1 (16.6)
Mouse	Emx1-cre	Serpina3n	708	MI	150	74 (49.3)	8 (10.8)	4 (50.0)	1 (12.5)	1 (12.5)	–
	Emx1-cre	Serpina3n	708	EL	150	113 (75.3)	27 (23.9)	10 (37.0)	1 (3.7)	5 (18.5)	3^c (11.1)

Transfer method: gRNA/Cas9 and long single-stranded DNA (lssDNA) transferred by microinjection (MI) or electroporation (EL). Embryos transferred: two-cell embryos were transferred into a surrogate mother. LD: large fragments deleted between two gRNA targeting sites. loxP and flox: positive for either one or two loxP sites, respectively
^aAll three rats carried a missense mutation, P56S, together with floxed alleles. Conditional: conditional knockouts by homozygous floxed alleles or heterozygous floxed with LD alleles in F0 animals
^bSite-specific recombination confirmed by crossing with Cre-driver mice
^cSite-specific recombination confirmed in Cre-expressing tissues of F0 mice
- not identified