“…MUPs are a group of 18e20 kDa proteins that are members of the lipocalin superfamily; these proteins have a characteristic b-barrel structure surrounding a central cavity that is capable of binding low molecular weight lipophilic molecules (see . MUPs are produced by both sexes but adult male urine typically contains an approximately three to four times higher concentration than female urine under laboratory housing conditions (Cheetham, Smith, Armstrong, Beynon, & Hurst, 2009); under more natural social conditions in seminatural populations, the investment among wild-stock house mice increases greatly, with males continuing to produce approximately twice as much as females but with considerable overlap in investment between the sexes (Hurst & Beynon, 2013). MUPs bind a number of ligands, including several androgen-specific volatiles that have known reproductive priming effects on females (Bacchini, Gaetani, & Cavaggioni, 1992;Mucignat-Caretta, Caretta, & Cavaggioni, 1995;Novotny, Ma, Wiesler, & Zidek, 1999) as well as a much wider range of volatile organic urinary metabolites (Kwak et al, 2012), which appear to include the volatile odours associated with MHC type (Singer, Tsuchiya, Wellington, Beauchamp, & Yamazaki, 1993).…”