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Genetically-based olfactory signatures persist despite dietary variation.

Kwak J, Willse A, Matsumura K, Curran Opiekun M, Yi W, Preti G, Yamazaki K, Beauchamp GK - PLoS ONE (2008)

Bottom Line: Chemical analyses of urinary volatile organic compounds (VOCs) extracted by solid phase microextraction (SPME) and analyzed by gas chromatography/mass spectrometry (GC/MS) are consistent with this inference.Although diet influenced VOC variation more than MHC, with algorithmic training (supervised classification) MHC types could be accurately discriminated across different diets.Thus, although there are clear diet effects on urinary volatile profiles, they do not obscure MHC effects.

View Article: PubMed Central - PubMed

Affiliation: Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA.

ABSTRACT
Individual mice have a unique odor, or odortype, that facilitates individual recognition. Odortypes, like other phenotypes, can be influenced by genetic and environmental variation. The genetic influence derives in part from genes of the major histocompatibility complex (MHC). A major environmental influence is diet, which could obscure the genetic contribution to odortype. Because odortype stability is a prerequisite for individual recognition under normal behavioral conditions, we investigated whether MHC-determined urinary odortypes of inbred mice can be identified in the face of large diet-induced variation. Mice trained to discriminate urines from panels of mice that differed both in diet and MHC type found the diet odor more salient in generalization trials. Nevertheless, when mice were trained to discriminate mice with only MHC differences (but on the same diet), they recognized the MHC difference when tested with urines from mice on a different diet. This indicates that MHC odor profiles remain despite large dietary variation. Chemical analyses of urinary volatile organic compounds (VOCs) extracted by solid phase microextraction (SPME) and analyzed by gas chromatography/mass spectrometry (GC/MS) are consistent with this inference. Although diet influenced VOC variation more than MHC, with algorithmic training (supervised classification) MHC types could be accurately discriminated across different diets. Thus, although there are clear diet effects on urinary volatile profiles, they do not obscure MHC effects.

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Comparison of t-statistics for within-diet MHC effects compared for two diets (top), and within-MHC Diet effects compared for two MHC types (bottom).Each number represents a compound, indexed in Table 3. Two separate test statistics are represented on horizontal and vertical axes. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. Regarding the relative concentration of a certain compound, in the top panel, red color represents compounds where the concentration is higher in B6 than in B6-H2k and blue color represents compounds where the concentration is higher in B6-H2k than in B6 regardless of diet. In the bottom panel, orange color represents compounds where the concentration is higher in Diet L than in Diet S and green color represents compounds where the concentration is higher in Diet S than in Diet L regardless of MHC type. The pink color represents the single compound where the concentration is higher in Diet L under B6 MHC type, but is lower in Diet L under B6-H2k MHC type.
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pone-0003591-g002: Comparison of t-statistics for within-diet MHC effects compared for two diets (top), and within-MHC Diet effects compared for two MHC types (bottom).Each number represents a compound, indexed in Table 3. Two separate test statistics are represented on horizontal and vertical axes. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. Regarding the relative concentration of a certain compound, in the top panel, red color represents compounds where the concentration is higher in B6 than in B6-H2k and blue color represents compounds where the concentration is higher in B6-H2k than in B6 regardless of diet. In the bottom panel, orange color represents compounds where the concentration is higher in Diet L than in Diet S and green color represents compounds where the concentration is higher in Diet S than in Diet L regardless of MHC type. The pink color represents the single compound where the concentration is higher in Diet L under B6 MHC type, but is lower in Diet L under B6-H2k MHC type.

Mentions: To further understand the influence of MHC×Diet interactions, and the stability of MHC effects across dietary treatments, we plotted t-statistics for MHC differences for a single dietary treatment verses the corresponding t-statistic for MHC differences on a different dietary treatment (see top panel of Figure 2). The positive correlation in the t-statistics of MHC differences across the two different diets (horizontal axis versus vertical axis) is an indication of MHC stability (or the relatively small influence of interactions). The bottom panel of Figure 2 compares t-statistics for diet differences, computed separately for each MHC type. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. The threshold lines correspond to an approximate unadjusted p-value of .05 and false discovery rate of .10. Regarding the relative concentration of a certain compound, in the top panel, a positive threshold value indicates that the concentration is higher in B6 than in B6-H2k, whereas a negative one indicates the concentration is higher in B6-H2k. Likewise, in the bottom panel, a positive value indicates that the concentration is higher in Diet L than in Diet S, while a negative one indicates the concentration is higher in Diet S. In the top panel, for example, the threshold values of 2,3-dehydro-exo-brevicomin (id# 20) fall near zero on both axes, indicating no significant MHC effect. In the bottom panel, however, the values are away from zero (positive) on both axes which are an indication of a significant diet effect. Its concentration is higher in Diet L than in Diet S regardless of MHC type. In the case of 3-penten-2-one (id# 4), the positive values on both axes of the top panel indicate that its concentration is higher in B6 mice than in B6-H2k mice regardless of diet. The values for this compound in the bottom panel fall near zero on both axes, indicating no significant diet effect.


Genetically-based olfactory signatures persist despite dietary variation.

Kwak J, Willse A, Matsumura K, Curran Opiekun M, Yi W, Preti G, Yamazaki K, Beauchamp GK - PLoS ONE (2008)

Comparison of t-statistics for within-diet MHC effects compared for two diets (top), and within-MHC Diet effects compared for two MHC types (bottom).Each number represents a compound, indexed in Table 3. Two separate test statistics are represented on horizontal and vertical axes. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. Regarding the relative concentration of a certain compound, in the top panel, red color represents compounds where the concentration is higher in B6 than in B6-H2k and blue color represents compounds where the concentration is higher in B6-H2k than in B6 regardless of diet. In the bottom panel, orange color represents compounds where the concentration is higher in Diet L than in Diet S and green color represents compounds where the concentration is higher in Diet S than in Diet L regardless of MHC type. The pink color represents the single compound where the concentration is higher in Diet L under B6 MHC type, but is lower in Diet L under B6-H2k MHC type.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2571990&req=5

pone-0003591-g002: Comparison of t-statistics for within-diet MHC effects compared for two diets (top), and within-MHC Diet effects compared for two MHC types (bottom).Each number represents a compound, indexed in Table 3. Two separate test statistics are represented on horizontal and vertical axes. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. Regarding the relative concentration of a certain compound, in the top panel, red color represents compounds where the concentration is higher in B6 than in B6-H2k and blue color represents compounds where the concentration is higher in B6-H2k than in B6 regardless of diet. In the bottom panel, orange color represents compounds where the concentration is higher in Diet L than in Diet S and green color represents compounds where the concentration is higher in Diet S than in Diet L regardless of MHC type. The pink color represents the single compound where the concentration is higher in Diet L under B6 MHC type, but is lower in Diet L under B6-H2k MHC type.
Mentions: To further understand the influence of MHC×Diet interactions, and the stability of MHC effects across dietary treatments, we plotted t-statistics for MHC differences for a single dietary treatment verses the corresponding t-statistic for MHC differences on a different dietary treatment (see top panel of Figure 2). The positive correlation in the t-statistics of MHC differences across the two different diets (horizontal axis versus vertical axis) is an indication of MHC stability (or the relatively small influence of interactions). The bottom panel of Figure 2 compares t-statistics for diet differences, computed separately for each MHC type. Horizontal and vertical dashed lines represent thresholds for statistical significance, so that the middle of central panel represents non-significance for both tests. The threshold lines correspond to an approximate unadjusted p-value of .05 and false discovery rate of .10. Regarding the relative concentration of a certain compound, in the top panel, a positive threshold value indicates that the concentration is higher in B6 than in B6-H2k, whereas a negative one indicates the concentration is higher in B6-H2k. Likewise, in the bottom panel, a positive value indicates that the concentration is higher in Diet L than in Diet S, while a negative one indicates the concentration is higher in Diet S. In the top panel, for example, the threshold values of 2,3-dehydro-exo-brevicomin (id# 20) fall near zero on both axes, indicating no significant MHC effect. In the bottom panel, however, the values are away from zero (positive) on both axes which are an indication of a significant diet effect. Its concentration is higher in Diet L than in Diet S regardless of MHC type. In the case of 3-penten-2-one (id# 4), the positive values on both axes of the top panel indicate that its concentration is higher in B6 mice than in B6-H2k mice regardless of diet. The values for this compound in the bottom panel fall near zero on both axes, indicating no significant diet effect.

Bottom Line: Chemical analyses of urinary volatile organic compounds (VOCs) extracted by solid phase microextraction (SPME) and analyzed by gas chromatography/mass spectrometry (GC/MS) are consistent with this inference.Although diet influenced VOC variation more than MHC, with algorithmic training (supervised classification) MHC types could be accurately discriminated across different diets.Thus, although there are clear diet effects on urinary volatile profiles, they do not obscure MHC effects.

View Article: PubMed Central - PubMed

Affiliation: Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA.

ABSTRACT
Individual mice have a unique odor, or odortype, that facilitates individual recognition. Odortypes, like other phenotypes, can be influenced by genetic and environmental variation. The genetic influence derives in part from genes of the major histocompatibility complex (MHC). A major environmental influence is diet, which could obscure the genetic contribution to odortype. Because odortype stability is a prerequisite for individual recognition under normal behavioral conditions, we investigated whether MHC-determined urinary odortypes of inbred mice can be identified in the face of large diet-induced variation. Mice trained to discriminate urines from panels of mice that differed both in diet and MHC type found the diet odor more salient in generalization trials. Nevertheless, when mice were trained to discriminate mice with only MHC differences (but on the same diet), they recognized the MHC difference when tested with urines from mice on a different diet. This indicates that MHC odor profiles remain despite large dietary variation. Chemical analyses of urinary volatile organic compounds (VOCs) extracted by solid phase microextraction (SPME) and analyzed by gas chromatography/mass spectrometry (GC/MS) are consistent with this inference. Although diet influenced VOC variation more than MHC, with algorithmic training (supervised classification) MHC types could be accurately discriminated across different diets. Thus, although there are clear diet effects on urinary volatile profiles, they do not obscure MHC effects.

Show MeSH