FIG 5 .

Nitrate driving anaerobic respiration is host derived. Groups (n = 4) of streptomycin-pretreated wild-type (WT) mice (C57BL/6) or iNOS-deficient mice (Nos2) were inoculated with an equal mixture of an S. Typhimurium SL1344 wild-type strain (CAL63) and a narG narZ napA mutant (CAL64), and organs were collected 4 days after infection. (A) Levels of mucosal iNOS protein in wild-type (lanes 1 to 4) and iNOS-deficient mice (lanes 5 to 8) were determined by Western blotting (top). Detection of tubulin by Western blotting served as a loading control (bottom). Each lane represents protein extracts isolated from one animal. Molecular masses (kilodaltons [kd]) of standard proteins are indicated on the right. (B) Representative images of sections from the cecal mucosa. (C) Blinded histopathology scoring of cecal inflammation showing average scores (bars) and scores of individual animals (squares). (D) Competitive indices of S. Typhimurium strains recovered from the colon contents of infected mice. Bars represent geometric means ± standard errors. Significance is based on the two-tailed Student t test. **, P < 0.01.