B6ntac

All mice were obtained from commercial vendors or bred in our colony using naïve mice from the same vendors. Mice were either male or female 129S1/SvImJ obtained from Jackson Laboratories (Stock # 002448; Bar Harbor, Maine), or C57BL/6NTac obtained from Taconic Farms (Model # B6NTac; Hudson, New York City), referred to hereafter as 129S1 and C57BL/6, respectively.
Experiments were conducted using mice aged 9 to 15 weeks at the time of testing with approximately equal number of males and females (males = 97, females = 90). Mice were housed by sex (2 to 5 per cage) in microisolation cages in a temperature-controlled (22°C) vivarium with a 14-hour/10-hour light/dark cycle for a minimum of 4 weeks prior to behavior studies. Mice were provided with ad libitum food and water. All experiments were conducted during the light phase. Prior to fear conditioning, mice were randomly assigned to two groups: US+ (footshocked) and US-(no footshock). Mice in the US+ group received a paired tone (CS+) and a footshock (US+) during fear conditioning. Mice in the US-group were exposed to the same tones but did not receive the paired footshock (US−). The number of mice used in each experiment is given in the figure legends. The Institutional Animal Care and Use Committee of the University of Michigan approved all experiments and guidelines for animal care set by the National Institutes of Health.

Wild-type (WT) mice were obtained from both Jackson Laboratories (C57BL/6J and B6.SJL-PtprcaPepcb/BoyJ) and Taconic Biosciences (B6NTac and B6.SJL-Ptprca/BoyAiTac). B6 mice were bred for dual congenic expression using a dam or sire from opposing place of purchase to eliminate any strain drift between the two WT strains. Wild-type B10.Q/Ai mice were originally obtained from Ron Schwartz, Institute of Allergy and Infection Diseases, NIH, Bethesda, MD. Wild-type B10.A-H2a H2-T18a/SgSnJ mice were obtained from Jackson laboratories. B10.A mice were bred for dual-congenic expression using a dam or sire from opposing genotypes. TCR-αβ KO mice were obtained from the Jackson Laboratories (B6.129S2-Tcratm1Mom/J). CD3ε knockout mice were obtained from NIAID/Taconic mouse contract (B10.A-Cd45a(Ly5a)/NAi N5). Animals were bred and maintained in modified specific pathogen-free facilities at the University of Maryland Baltimore Experiments were performed with animals at least 6 weeks of age and approved by University of Maryland Baltimore Institutional Animal Care and Use Committee.

Wild-type mice were obtained from both the Jackson Laboratory (C57BL/6J and B6.SJL-Ptprc^aPepc^b/BoyJ) and Taconic Biosciences (B6NTac and B6.SJL-Ptprc^a/BoyAiTac). B6 mice were bred for dual congenic expression using a dam or sire from opposing place of purchase to eliminate any strain drift between the two wild-type strains. IL-12p40−/− (B6.129S1-Il12bt^m1Jm/J) and IL-12p35−/− (B6.129S1-Il12at^m1Jm/J) were sourced from the Jackson Laboratory. IL-12p40−/− mice were backcrossed to wild-type mice (B6.SJL-PtprcaPepcb/BoyJ) to generate CD45.1 congenic IL-12p40−/− mice. SMARTA TCR transgenic mice were obtained from Jackson Laboratories (B6.Cg-Ptprca Pepcb Tg(TcrLCMV)1Aox/PpmJ). For all experiments, both female and male mice between 4 and 35 weeks of age were used. Animals were bred and maintained under specific pathogen free (SPF) conditions at the University of Maryland, Baltimore. Experiments were performed with animals at least four weeks of age for bone marrow isolation and six weeks of age for all other experiments and approved by the University of Maryland, Baltimore Institutional Animal Care and Use Committee.