Novel C57BL/6 mice strains carrying either Arg41Gln or Arg46Gln mutations in PAR1 were generated. (A) C57BL/6 embryonic stem cells were used to generate mutations in mice using homologous recombination methods to incorporate the targeting vector pBS-FRT-PGK-NEO-FRT, as outlined in the panel and as described in supplemental Data. (B-C) To identify genotype for offspring from mating of QQ41 and QQ46 heterozygotes, PCR assays gave clear indication of genotypes, namely RR, RQ, or QQ, as shown for residues (B) 41 and (C) 46, respectively (see supplemental Data for methods). The DNA gel images were obtained from Bio-Rad GELDOC XR equipped with the image software Quantity One from Bio-Rad (Hercules, CA). (D) To record fetus development as observed at days 10 (E10) and 12 (E12) following plug formation, pictures of Wt and QQ41 embryos were taken under normal lighting. At E10, some QQ41 embryos were significantly smaller and underdeveloped compared with Wt embryos; however, no systematic analysis of embryogenesis was made.