EEG delta power in NREM sleep after SD is associated with <i>Kif16b</i> and <i>Wrn</i>.

<p>(A) NREM sleep EEG spectra in the first 3 h after SD (ZT6–9) for the 2 BXD lines that displayed the lowest and highest EEG activity in the fast delta frequency band (2.5–4.25 Hz, δ2; top, see panel E) and for the 2 BXD lines that displayed the smallest and largest increase (or gain) in EEG power in the slow delta band (1.0–2.25 Hz, δ1; bottom, see panel E). Spectra were “1/f-corrected” (and therefore not directly comparable to the values in panel E) for better visualization of activity in higher frequency bands (theta [5–9 Hz, θ], sigma [11–16 Hz, σ], beta [18–30 Hz, β], and slow [32–55 Hz, γ1] and fast gamma [55–80 Hz, γ2]). Subsequent analyses were performed without this correction. (B) QTL mapping and prioritization for δ2 power identified a significant association on chromosome 2 and <i>Kif16b</i> in cortex as top-ranked gene (top). For the δ1 increase after SD, we obtained a suggestive QTL on chromosome 8 and a significant prioritization score for the DNA-helicase <i>Wrn</i>. (C) Hiveplot visualization of network connections for the δ1 and δ2 power after SD (top-left panels) and the SD-induced increase in δ1 and δ2 power over baseline (bottom-left panels). Note the marked differences in the networks and QTLs regulating the expression of these 2 delta bands. Right hiveplots highlight <i>Kif16b</i> in the δ2 power–associated network (top), and <i>Wrn</i> in the network associated with the δ1 increase (bottom). Only <i>Kif16b</i> expression in the cortex was linked to the chromosome 2 <i>cis</i>-<i>e</i>QTL and was not associated with any metabolite. <i>Wrn</i> expression was significantly linked to the chromosome 8 <i>cis-e</i>QTL and to the long phosphatidylcholine, PC-ae-C38:5. (D) <i>Kif16b</i> is highly significantly down-regulated in cortex (left), while it remains unchanged in liver after SD (<i>p</i> = 0.15; not shown). Also, <i>Wrn</i> expression was strongly down-regulated by SD in cortex (right) and only marginally so, albeit significantly, in liver (<i>p</i> = 0.02; not shown). (E) Strain distribution patterns. BXD lines carrying a <i>B6-</i>allele on the chromosome 2–associated region showed higher δ2 power after SD (left) and a significantly higher <i>Kif16b</i> expression (<i>p</i> = 1.3e−15; second to left) than <i>D2-</i>allele carriers. <i>D2-</i>allele carriers of the chromosome 8–associated region showed a larger δ1 increase after SD (second to right) as well as a significantly larger decrease in <i>Wrn</i> expression after SD (right) than <i>B6-</i>allele carriers. For color-coding of genotypes, see <a href="" target="_blank">Fig 4</a>. CPM, counts per million; Ctr, control; EEG, electroencephalography; <i>e</i>QTL, expression quantitative trait locus; FDR, false discovery rate; <i>Kif16b</i>, <i>Kinesin family member 16B</i>; NREM, non-REM; PC-ae, phosphatidylcholine acyl-alkyl; QTL, quantitative trait locus; SD, sleep deprivation; <i>Wrn</i>, <i>Werner syndrome RecQ like helicase</i>; ZT, zeitgeber time</p>