<p>Supplementary Information</p><p>Fig. S1. PCA score plots (A, B, E, F, I, J) and PLS-DA score plots (C, D, G, H, K, L) from the GC-TOF- MS (A-D), UPLC-Q-TOF-MS (E-H), and NanoMate LTQ-MS (I-L) data sets for the aqueous extracts of mouse skin after exposure to UVB radiation after 6 and 12 wks, respectively. (A, E, I) PCA score plots from the NC and UC groups after 6 wks; (B, F, J) PCA score plots from the NC and UC groups after 12 wks. (C, G, K) PLS-DA score plots from the NC and UC groups after 6 wks; (D, H, L) PLS-DA score plots from the NC and UC groups after 12 wks. ■ - 6 wks, NC; ● - 6 wks, UC; □ - 12 wks, NC; ○ - 12 wks, UC. Fig. S2. Structures and MS/MS spectra of representative ceramides: N(17:0)S(18:1) (A), N(24:0)dS(18:0) (B), A(18:0)dS(18:0) (C), A(20:0)S(18:1) (D), N(16:0)P(18:0) (E), and N(20:0)H(17:1) (F) Fig. S3. PCA score plots from the GC-TOF-MS (A), UPLC-Q-TOF-MS (B), and NanoMate LTQ-MS (C) data sets for the aqueous extracts of mouse skin after exposure to UVB radiation after 6 and 12 wks. ■ - 6 wks, NC; ● - 6 wks, UC; □ - 12 wks, NC; ○ - 12 wks, UC. Table S1. Summary of parameters for assessment of the quality of PLS-DA and OPLS-DA models</p><p>2 a 2 a 2 b c Week R Xcum R Ycum Q Ycum P PLS-DA GC-TOF-MS 6 0.326 0.944 0.770 < 0.001 12 0.371 0.991 0.922 < 0.001 UPLC-Q-TOF-MS 6 0.313 0.997 0.820 0.051 12 0.317 0.990 0.909 < 0.001 Nano LTQ 6 0.528 0.497 0.400 0.022 12 0.618 0.969 0.543 0.261 OPLS-DA GC-TOF-MS 6 0.481 0.998 0.843 < 0.001 12 0.439 0.999 0.920 < 0.001 UPLC-Q-TOF-MS 6 0.504 1.000 0.685 0.093 12 0.295 0.994 0.915 < 0.001 Nano LTQ 6 0.935 0.879 0.484 0.325 12 0.954 0.969 0.885 0.001 a 2 2 R Xcum and R Ycum are the cumulative modeled variation in X and Y matrix, respectively. b 2 Q Ycum is the cumulative predicted variation in Y matrix. cP is p value obtained from cross validation ANOVA of OPLS-DA.</p><p>Table S2. Quantitative analysis of trans- and cis-UCA and cholesterol in mouse skin samples using GC- TOF-MS (µg/mg of skin aqueous extract) Weeks Group trans-UCA cis-UCA cholesterol NC 50.04 ± 6.01 nq 107.90 ± 76.82 6 week UC 43.31 ± 5.33* 20.10 ± 2.76 105.87 ± 54.16 NC 51.36 ± 5.61 nq 228.95 ± 93.34 12 week UC 41.73 ± 8.36* nq 62.34 ± 27.22* The values are expressed as the mean ± SD. The data were evaluated for statistical significance with Student’s t-test. Asterisks indicate statistically significant differences from the UC group (*p < 0.05), respectively. nq, not quantified.</p><p>Table S3. Identification of skin ceramides which were found in mouse skin samples Identified ceramide Identified ceramide No.1 MW2 [M+Ac]- 3 Total No.1 MW2 [M+Ac]- 3 Total Type4 Type4 Carbon Carbon 1 553.5 612.5 AS 34:1 20 677.6 736.6 NS 44:1 555.4 614.4 NP 34:0 21 679.4 738.4 NdS 44:0 2 555.4 614.4 AdS 34:0 693.4 752.4 NdS 45:0 22 3 565.5 624.5 NS 36:1 693.4 752.4 NH 44:1 4 567.5 626.5 NdS 36:0 23 707.4 766.4 NdS 46:0 5 581.6 640.6 NH 36:1 24 709.7 768.7 NP 45:0 6 593.3 652.3 NS 38:1 25 721.3 780.3 NdS 47:0 7 595.3 654.3 NH 37:1 26 723.7 782.7 NP 46:0 8 607.6 666.6 NS 39:1 27 733.5 792.5 NS 48:1 9 609.3 668.3 NdS 39:0 735.4 794.4 NdS 48:0 28 10 621.5 680.5 NS 40:1 735.4 794.4 NH 47:1 11 623.6 682.6 NdS 40:0 29 749.6 808.6 NH 48:1 12 635.4 694.4 NS 41:1 30 751.7 810.7 NP 48:0 13 637.6 696.6 NdS 41:0 31 761.5 820.5 NS 50:1 14 639.7 698.7 NP 40:0 32 763.5 822.5 NH 49:1 15 649.4 708.4 NS 42:1 33 765.7 824.7 NP 49:0 16 651.4 710.4 NdS 42:0 34 777.5 836.5 NH 50:1 17 663.4 722.4 NS 43:1 35 779.7 838.7 NP 50:0 18 665.4 724.4 Nds 43:0 36 789.5 848.5 NS 52:1 19 667.4 726.4 NP 42:0 1No. means the number of the identified cermides. 2 MW, molecular weight 3[M+Ac]-, Acetate adduct 4A, α-hydroxy fatty acid; N, non-hydroxy fatty acid; S, sphingosine; P, phytoshpingosine; dS, dihydrosphingosine; H, 6-hydroxysphingosine</p>