Table 2.

Experimental Design for the Molecular Pathogenesis Experiment

Exposure	Target concentration (ppm)	Genotype	End point∗
Air	NA	Wild type, Dcxr ko1,†Dcxr ko2‡	Lung and nose histopathology; lung and olfactory bulb mRNA; lung airway enriched fraction Western immunoblot; bronchial transmission electron microscopy
Diacetyl	200 ppm	Wild type, Dcxr ko1,†Dcxr ko2‡	Lung and nose histopathology; lung and olfactory bulb mRNA; lung airway enriched fraction Western immunoblot; bronchial transmission electron microscopy

Wild-type mice and two different Dcxr-knockout mice were exposed to air or 200 ppm diacetyl.

NA, not applicable.

^∗The left lung lobe was used for histopathology, and the right lung lobes were used for mRNA end points. The olfactory bulb was used for mRNA. To reduce animal use, immunofluorescence of olfactory bulb used tissues from wild type and Dcxr ko1 in the 200 ppm group from the dose-response study. Western immunoblot and electron microscopy samples were from air or 200 ppm diacetyl-exposed Dcxr-ko2 mice.

^†Dcxr-ko1 mice are C57BL6-Dcxr ^{tm1 (KOMP)Vlcg}/N mice, which have the Dcxr gene deleted and replaced by a selection cassette that contains an initial LoxP site, followed by a human ubiquitin promoter driving a neomycin response element and a second LoxP site.

^‡Dcxr-ko2 mice are C57BL6-Dcxr ^{tm1.1 (KOMP)Vlcg}/N that have both the Dcxr gene and the selection cassette deleted from the mouse genome.