Reca1

The strains used in this study were E. coli Top10 (F⁻, mcrA, Δ(mrr-hsdRMS-mcrBC), φ80, lacZΔM15, ΔlacX74, deoR, nupG, recA1, araD139, Δ(ara-leu)7697, galU, galK, rpsL(Str^r), endA1) (Invitrogen), E. coli BL21(DE3) (F⁻ompT gal dcm lon hsdS_B(r_B⁻m_B⁻) λ(DE3[lacI lacUV5-T7p07 ind1 sam7 nin5]) [malB⁺]_K-12(λ^S)) (Invitrogen), CWG1238 (S. Typhi H251.1 ΔwaaG::kan; Km^r) (9 (link)), and B. bronchiseptica RB50 (50 (link)). E. coli and S. Typhi were routinely grown at 37 °C in lysogeny broth (LB) supplemented with the appropriate antibiotic (100 μg mL⁻¹ ampicillin, 34 μg mL⁻¹ chloramphenicol, 50 μg mL⁻¹ kanamycin, or 10 μg mL⁻¹ tetracycline) and 100 μg mL⁻¹ 2,3-dihydroxybenzoic acid when necessary (CWG1238). B. bronchiseptica RB50 was grown at 37 °C in LB (Bvg⁺ phase) or LB supplemented with 50 mM MgSO₄ (Bvg⁻ phase). In B. bronchiseptica, the capsule locus deletion mutant (Δcap) was constructed by replacing the entire locus except the 3′ half of kpsS and tviD with a kanamycin resistance cassette, using an approach as described previously (69 (link)).

Vascular association with cell proliferation was detected using endothelial antigen-1 (RECA-1) and Ki-67 markers to study the association of blood vessels and cell proliferation [35 (link)]. Right half of the brains were continuously cut (20 μm) between Bregma −2.3 to 6.3 mm to get total dentate gyrus using a cryostat (Cryostat Series HM550 Microm international, A.S. Science Co. Ltd., Walldrof, Germany). Every 15th section from the entire dentate gyrus was selected using a probability sampling method to get 9 sections from each brain [12 (link),31 (link)]. The sections were first reacted with mouse Ki-67 monoclonal antibody (1:150, NOVOCASTRA, UK) for 60 min, then treated with rabbit anti-mouse Alexa Fluor 488 antibody (1:250, Invitrogen, USA) for 60 min. The sections were incubated with primary antibody monoclonal mouse RECA-1 (1:100), Invitrogen, USA) for 60 min and then reacted with goat anti-rat Alexa Fluor 568antibody (1:250, Invitrogen, USA). Each section was reacted with DAPI (1:6000, Molecular probes, Eugene, OR, USA) diluted with PBS about 30 s to enhance a contrasting background, thereafter each section was mounted with glycerol.