Quantitative Analysis of Mouse Urine Volatiles: In Search of MHC-Dependent Differences

Abstract

Genes of the major histocompatibility complex (MHC), which play a critical role in immune recognition, influence mating preference and other social behaviors in mice. Training experiments using urine scent from mice differing only in the MHC complex, from MHC class I mutants or from knock-out mice lacking functional MHC class I molecules (ß2m-deficient), suggest that these behavioral effects are mediated by differences in MHC-dependent volatile components. In search for the physical basis of these behavioral studies, we have conducted a comparison of urinary volatiles in three sub-strains of C57BL/6 mice, a ß2m-deficient mutant lacking functional MHC class I expression and two unrelated inbred strains, using the technique of sorptive extraction with polydimethylsiloxan and subsequent analysis by gas chromatography/mass spectrometry. We show (i) that qualitative differences occur between different inbred strains but not in mice with the C57BL/6 background, (ii) that the individual variability in abundance in the same mouse strain is strongly component-dependent, (iii) that C57BL/6 sub-strains obtained from different provenance show a higher fraction of quantitative differences than a sub-strain and its ß2m-mutant obtained from the same source and (iv) that comparison of the spectra of ß2m mice and the corresponding wild type reveals no qualitative differences in close to 200 major and minor components and only minimal differences in a few substances from an ensemble of 69 selected for quantitative analysis. Our data suggest that odor is shaped by ontogenetic, environmental and genetic factors, and the gestalt of this scent may identify a mouse on the individual and population level; but, within the limits of the ensemble of components analysed, the results do not support the notion that functional MHC class I molecules influence the urinary volatile composition.

Mouse urinary peptides provide a molecular basis for genotype discrimination by nasal sensory neurons

“…The picture on the variability of urinary peptides emerging from this study is very similar to that described for urinary volatiles 16 . In natural wild populations, urinary peptide patterns will differ qualitatively and quantitatively between individuals.…”

“…However, no qualitative and only negligible quantitative variations in a large number of different volatiles have been observed when comparing urine mixtures of groups of an inbred wild-type strain and a congenic knock-out strain lacking functional MHC class I molecules. In contrast, more quantitative differences were observed between groups of the same inbred wild-type strain derived from different breeders 16 (for a review, see Kwak et al 17 ). Hence, whereas variability in small airborne organic molecules may be important for recognition of individual scent owners 18,19 , physical evidence for an influence of the MHC on urinary volatiles remains elusive.…”

The Genetic Basis of Kin Recognition in a Cooperatively Breeding Mammal

“…Given that MHC and ESP regions exhibited strong linkage in our mice, this also implies that mice did not use Esp genes as a marker for kin recognition either. To date, there is no convincing evidence from mouse studies that MHC is used as a genetic kinship marker among genetically heterogeneous animals, or that MHC can provide a consistent kinship signature that is recognizable across different genetic backgrounds [24,39,[56][57][58][59], in strong contrast to recognition of MUP type.…”

The male sex pheromone darcin stimulates hippocampal neurogenesis and cell proliferation in the subventricular zone in female mice

“…SDS-PAGE analysis confirmed that CD-1 strain males express normal adult male levels of darcin, though a little lower than that typical of wild or C57BL/6 strain males at approximately 8% of total urinary MUP output (Figure 2E ). By contrast, BALB/c males express extremely low levels of the darcin pheromone (<0.5% of total MUP output, Roberts et al, 2010 , Figure 2E ), although they have normal expression of other known male-specific pheromones (Willse et al, 2006 ; Röck et al, 2007 ; Haga et al, 2010 ). Urine from singly housed BALB/c males failed to stimulate a significant increase in neurogenesis (Figure 2Ac ).…”