Fig. 6
From: A population-based gene expression signature of molecular clock phase from a single epidermal sample
Population-level skin candidate biomarkers work for a single human epidermis sample. a Twelve marker genes in the first two sparse principal components (SPCs) were selected by ZeitZeiger. b Validation of skin candidate biomarkers using epidermis samples from 9 participants that were excluded from the training set. The epidermis samples were collected every 6 h over a circadian day. Average predicted phases of samples collected at 12 AM, 6 AM, 12 PM, and 6 PM are indicated with red, orange, cyan, and purple dashed lines, respectively. c Validation of skin candidate biomarkers using longitudinal epidermis samples from 18 participants in Spörl et al. [29] (Additional file 1: Table S1). The epidermis samples were collected every 5 h from 9:30 AM to 7:30 PM. Average predicted phases of samples collected at 9:30 AM, 2:30 PM, and 7:30 PM are indicated with magenta, green, and blue dashed lines, respectively. The predicted molecular clock phase is between 0 and 2π, with 0 indicating the peak phase of ARNTL