Fig. 1: Deletion of all members of the MS4A family prevents in vivo detection of MS4A ligands by necklace OSNs and the innate avoidance behaviors triggered by these ligands.

A Schematic representation of the genomic organization of the entire Ms4a family of genes in a tandem array on chromosome 19. B Example images of the cul-de-sac regions (where necklace cells reside) of the main olfactory epithelia of mice exposed to the indicated odorant, co-labeled for the necklace cell marker Car2 (magenta) and the neuronal activity marker phospho-S6 (pSerine240/244) (green) from wildtype (left panels) or Ms4a cluster knockout animals (right panels). C Quantification of the average pS6 signal/necklace cell above the average pS6 signal/necklace cell when no odor is introduced (water) in wildtype mice (left panel) or Ms4a cluster knockout mice (right panel) when exposed to the indicated odors. Data are presented as mean ± SEM. For wildtype mice (left panel), n = 222 cells over three independent experiments (EUG), n = 305 cells over four independent experiments (CS₂), n = 521 cells over six independent experiments (2,5-DMP), n = 609 cells over five independent experiments (OA), n = 476 cells over four independent experiments (ALA); for Ms4a cluster knockout mice (right panel), n = 382 cells over three independent experiments (EUG), n = 482 cells over three independent experiments (CS₂), n = 316 cells over four independent experiments (2,5-DMP), n = 362 cells over three independent experiments (OA), n = 325 cells over two independent experiments (ALA). The number of independent experiments (mice) is indicated in brackets, ****p < 0.0001, Dunnett’s test following one-way ANOVA compared to eugenol (EUG) exposure. D Heat maps of the occupancy of wildtype (left panels) or cluster knockout mice (right panels) in the odor avoidance chamber in response to the indicated odorants. Small square represents the location of the odorant, and the dashed line demarcates the odor avoidance zone from the rest of the chamber. Scale bar, 5 cm. E Quantification of odor avoidance behavior. The distance between the average center of mass of the mouse and the location of the odorant (top panels) and the proportion of time spent in the odorized zone (bottom panels) were determined for wildtype mice (left) and Ms4a cluster knockout mice (right). Each circle represents an individual mouse. Data are presented as mean ± SEM. For wildtype mice (left panels), n = 8 mice examined over five independent experiments (Blank), n = 9 mice over five independent experiments (Water), n = 7 mice over four independent experiments (2,5-DMP), n = 7 mice over four independent experiments (TMT); for cluster knockout mice (right panels), n = 15 mice over 11 independent experiments (Blank), n= nine mice over seven independent experiments (Water), n = 10 mice over six independent experiments (2,5-DMP), n = 7 mice over four independent experiments (TMT). **p < 0.01, ***p < 0.001, Dunnett’s test following one-way ANOVA compared to water exposure. Source data are provided as a Source Data file.