Fig. 3.

Seasonal and monthly variation in protein abundance levels. (a) Mean sun hours per season (Winter, Spring, Summer, Autumn) (b–d) proteins abundance levels (NPX) over seasons for Latency-associated peptide transforming growth factor beta-1 (LAP-TGF-beta-1), Heat shock 27 kDa protein (HSP 27) and Interleukin-20 receptor subunit alpha (IL-20RA). Red connections indicate nominally significant (p < 0.05, two-sided Wilcox test) differences between pair of seasons. (e) Sun hours per month. (f–g) Monthly differences in protein abundance levels for two proteins (LAP-TGF-beta-1 and HSP-27). Solid lines represent responses from linear models fitted with 0–11 months offset between sunlight and protein abundance levels (NPX). Blue lines indicate nominally significant contribution of sunlight hours to protein abundance levels for a specific offset. The best model in (f) was found for an offset of 8 months delay, and for (g) with a 1 month delay. (h) Fraction of variance explained by sunlight (as a proxy variable for a number of possible factors) on protein abundance levels after adjusting for storage time and age of the individual.