Artemis gene targeting. (A) Schematic representation of the targeted region of murine Artemis locus (WT, Art⁺), targeting construct, targeted allele, neo^R deleted, and exon 12 floxed (Art^fl) allele, and neo^R deleted and exon 12 deleted (Art⁻) allele. The PGK-neo^R cassette is inserted in the opposite transcriptional orientation. Restriction sites: E, EcoRI. Filled boxes represent exons; filled triangles, LoxP sites. (B) Screening of Art^+/− and Art^fl/+ mouse line progenies by PCR on tail DNA, using primers 1 (K5.4), 2 (K5.1), 3 (K5.3), and 5 (K5.5); see “Generation of ES cells, Art-KO, and conditional Art-KO mice.” Filled box represents exon 12; filled triangles, LoxP sites. Primers 1 and 3 reveal a 1-kb WT (Art⁺) and 0.4-kb (Art⁻) deleted alleles, respectively. Primers 2 and 3 reveal a 0.25-kb WT and 0.34-kb flox (Art^fl) alleles, respectively. Vertical lines have been inserted to indicate repositioned gel lanes. (C) RT-PCR analysis of Artemis transcripts in Art^−/− mice. RT-PCR was performed on total RNA from spleen of Art^−/− (KO) and littermate control Art^+/+ (WT) mice. Specific primers were used to detect Artemis transcripts containing exons 1 to 14, 1 to 12, and 1 to 11. HPRT-specific PCR was used as loading control.