title: Comparison of male chimeric mice generated from microinjection of JM8.N4 embryonic stem cells into C57BL/6J and C57BL/6NTac blastocysts.
abstract: To identify ways to improve the efficiency of generating chimeric mice via microinjection of blastocysts with ES cells, we compared production and performance of ES-cell derived chimeric mice using blastocysts from two closely related and commonly used sub-strains of C57BL/6. Chimeras were produced by injection of the same JM8.N4 (C57BL/6NTac) derived ES cell line into blastocysts of mixed sex from either C57BL/6J (B6J) or C57BL/6NTac (B6NTac) mice. Similar efficiency of production and sex-conversion of chimeric animals was observed with each strain of blastocyst. However, B6J chimeric males had fewer developmental abnormalities involving urogenital and reproductive tissues (1/12, 8%) compared with B6NTac chimeric males (7/9, 78%). The low sample size did not permit determination of statistical significance for many parameters. However, in each category analyzed the B6J-derived chimeric males performed as well, or better, than their B6NTac counterparts. Twelve of 14 (86%) B6J male chimeras were fertile compared with 6 of 11 (55%) B6NTac male chimeras. Ten of 12 (83%) B6J chimeric males sired more than 1 litter compared with only 3 of 6 (50%) B6NTac chimeras. B6J male chimeras produced more litters per productive mating (3.42 ± 1.73, n = 12) compared to B6NTac chimeras (2.17 ± 1.33, n = 6). Finally, a greater ratio of germline transmitting chimeric males was obtained using B6J blastocysts (9/14; 64%) compared with chimeras produced using B6NTac blastocysts (4/11; 36%). Use of B6J host blastocysts for microinjection of ES cells may offer improvements over blastocysts from B6NTac and possibly other sub-strains of C57BL/6 mice.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Fielder
authors.forename: Charles S
authors.initials: CS
authors.lastname: Yi
authors.forename: Juliet
authors.initials: J
authors.lastname: Masumi
authors.forename: Katrina G
authors.initials: KG
authors.lastname: Waymire
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Chen
authors.forename: Shuling
authors.initials: S
authors.lastname: Wang
authors.forename: Kai-Xuan
authors.initials: KX
authors.lastname: Shi
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Wallace
authors.forename: Grant R
authors.initials: GR
authors.lastname: MacGregor
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D002678:Chimera / Q000502:physiology*; D004247:DNA / Q000032:analysis / Q000235:genetics; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D005260:Female; D005854:Germ Cells / Q000166:cytology / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008845:Microinjections; D060888:Real-Time Polymerase Chain Reaction; D013091:Spermatogenesis / Q000502:physiology*
chemical_list: D004247:DNA