The concentrations of ARA-containing phospholipid species in the parietal cortex of animals fed a diet with adequate amounts of ω3 PUFAs (black bars) and a diet deficient in ω3 PUFAs (gray bars) in nmoles / gm tissue.

<p>Each result is the mean of 6 different brain extracts, and the error bars represent standard deviations. The absence of a bar for an sn1 chain indicates that the corresponding MRM transition was monitored, but no signal detected. There were no statistically significant differences between groups. See text for information about the nature of quantitative uncertainty in these data.</p

ARA, DPA, and DHA content in the brain tissue of animals fed diets with adequate or deficient amounts of ω3-PUFAs.

<p>Fractions correspond to the five normal phase LC fractions described previously [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164326#pone.0164326.ref018" target="_blank">18</a>]. GC/MS determinations were made as described in methods. LC/MS/MS results are the sum of all data in Figs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164326#pone.0164326.g001" target="_blank">1</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164326#pone.0164326.g003" target="_blank">3</a>. Uncertainties for the five fractions are standard deviations of 6 measurements. Uncertainties for the fraction totals were calculated according to the variance sum law. All units are nmoles/gm tissue wet weight.</p

Increased ω6-Containing Phospholipids and Primary ω6 Oxidation Products in the Brain Tissue of Rats on an ω3-Deficient Diet

<div><p>Polyunsaturated fatty acyl (PUFA) chains in both the ω3 and ω6 series are essential for normal animal brain development, and cannot be interconverted to compensate for a dietary deficiency of one or the other. Paradoxically, a dietary ω3-PUFA deficiency leads to the accumulation of docosapentaenoate (DPA, 22:5ω6), an ω6-PUFA chain that is normally scarce in the brain. We applied a high-precision LC/MS method to characterize the distribution of DPA chains across phospholipid headgroup classes, the fatty acyl chains with which they were paired, and the extent to which they were oxidatively damaged in the cortical brain of rats on an ω3-deficient diet. Results indicate that dietary ω3-PUFA deficiency markedly increased the concentrations of phospholipids with DPA chains across all headgroup subclasses, including plasmalogen species. The concentrations of phospholipids containing docosahexaenoate chains (22:6ω3) decreased 20–25%, while the concentrations of phospholipids containing arachidonate chains (20:4ω6) did not change significantly. Although DPA chains are more saturated than DHA chains, a larger fraction of DPA chains were monohydroxylated, particularly among diacyl-phosphatidylethanolamines and plasmalogen phosphatidylethanolamines, suggesting that they were disproportionately subjected to oxidative stress. Differences in the pathological significance of ω3 and ω6 oxidation products suggest that greater oxidative damage among the ω6 PUFAs that increase in response to dietary ω3 deficiency may have pathological significance in Alzheimer’s disease.</p></div

The ratio of +O addition (oxidation) for selected PE species in the parietal cortex of animals fed the diet deficient in ω3 PUFAs, relative to the diet with adequate amounts of ω3 PUFAs.

<p>The three panels represent PE species containing either oxidized (a) ARA, (b) DPA, or (c) DHA. Thin blue bars in each panel represent results for the <i>sn</i>-1 chains indicated, which correspond to the 6 most abundant PE species in Figs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164326#pone.0164326.g001" target="_blank">1</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164326#pone.0164326.g003" target="_blank">3</a>. The wide red cross-hatched bar in each panel is the average ratio for all 6 species in aggregate, with a standard error of the mean indicated. By 2-tailed T test of unpaired samples with unequal variances, the ratio for 22:5(+O)-PE species in aggregate (1.63) differs from the ratio for 20:4(+O)-PE species (1.16) at P ≤ 0.05, and from the ratio for 22:6(+O)-PE species (1.01) at P ≤ 0.01.</p

Identification of 18:0/22:5(OH)-PE by LC/MS/MS.

<p>(a) Single reaction monitoring chromatogram of the 808.8 → 345.2 transition, with solvent flow reduced to 850 μl/min. 18:0/22:5(+O)-PE eluted 0.3 min later than 18:0/22:5-PE, consistent with the slightly greater polarity of the oxidized species. (b) Product ions produced by the <i>m/z</i> 808.8 parent ion at 12.6 min. Due to the low concentrations of the parent species (a maximum of only 400 transitions/sec observed in panel a), this spectrum was collected with the Q1 resolution set to “unit”, while the Q3 resolution was set to “open”. The position of the oxygen on the 22:5 chain is unknown, and possibly variable. The identity of the <i>m/z</i> 672.9 and 749.5 product ions is not known.</p

Nonlinear gene expression changes in relation to age during Development, for 10 genes.

<p>Data were fit by following equation, Y = (Y0 - Plateau)*exp(-K*A) + Plateau (where Y = expression level at age A, and Y0 expression level at A = 0 years).</p

Statistically significant correlations of gene expression with age during Development and Aging intervals.

<p>Statistical significance, corrected for 98 comparisons, taken as p < 0.0005. Nonsignificant values not shown.</p><p>Statistically significant correlations of gene expression with age during Development and Aging intervals.</p

Pathways of phosphoinositide metabolism.

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132675#sec008" target="_blank">Results</a> section for details.</p

Heat maps for pairwise correlations of genes in Development (A) and Aging (B) intervals.

<p>Correlations or p-values are hierarchically clustered using the centroid linkage method.</p

Significant correlations between pairs of genes located on the same chromosomal band during the Development and Aging intervals.

<p>Nonsignificant correlations not shown.</p><p>Significant correlations between pairs of genes located on the same chromosomal band during the Development and Aging intervals.</p