. 2002 Jul 15;21(14):3888–3897. doi: 10.1093/emboj/cdf379

Table I. In vivo recombination at psi and psiDC in E.coli strains carrying mutant xer genes.

Plasmid	Genotype
	xerC⁺ xerD⁺	xerC⁺ xerD^YF	xerC^YF xerD⁺	xerC^YF xerD^YF
p-psi.psi	+++	+++	–	–
p-psiDC.psiDC	++	–	+	–

Plasmids were transformed into strains carrying the chromosomal copies of xer alleles indicated. The extent of recombination observed by agarose gel electrophoresis after overnight growth is indicated as: +++, 100% of substrate converted to product; ++, 50% of substrate converted to product; +, 15% of substrate converted to product; –, no detectable recombination.