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. 2016 Sep 1;4:e2237. doi: 10.7717/peerj.2237

Table 3. Mixed models testing how the exposure to oxidative stress (diquat) interacted with the dietary carotenoid treatment at the end of the experiment.

The level of each dependent variable in the sampling event precedent to the diquat exposure is included as a covariate for color and blood variables. The models describe the backward step (using the P = 0.10 threshold) previous to remove the diquat × CAR interaction (i.e. when it was non-significant; Methods).

Dependent variable Terms in the model Slope SE F df P
Eye rings redness Carotenoid 24.93 3,147 <0.001
Diquat 0.03 1,146 0.859
Sex 0.8 1,146 0.373
Carotenoid × diquat 1.38 3,146 0.252
Sex × diquat 3.21 1,146 0.075
Total brightness −0.00004 0.00002 6.25 1,147 0.014
Eye ring redness in day 48 0.291 0.064 20.95 1,147 <0.001
Liver vitamin A 0.0004 0.0003 1.33 1,147 0.251
Eye ring tocopherol 0.025 0.012 4.43 1,146 0.037
Eggs during diquat experiment −0.002 0.0008 4.44 1,146 0.037
Bill redness Carotenoid 17.19 383.2 <0.001
Diquat 4.23 176.6 0.043
Sex 1.46 175.9 0.231
Carotenoid × diquat 1.03 374.3 0.382
Sex × carotenoid 1.34 369.7 0.269
Total brightness −0.0001 0.00003 23.14 1,143 <0.001
Bill redness in day 48 0.151 0.056 7.4 1,134 0.007
Bill tocopherol 0.048 0.014 11.7 1,118 <0.001
Liver vitamin A 0.001 0.0004 5.72 1,138 0.018
Leg redness Carotenoid 10.55 3,136 <0.001
Diquat 0.23 1,137 0.631
Sex 3.98 1,138 0.048
Carotenoid × diquat 0.67 3,137 0.575
Sex × diquat 0.33 1,137 0.567
Sex × carotenoid 1.69 3,137 0.173
Red chip 1.018 0.221 21.28 128.8 <0.001
Leg redness in day 48 0.594 0.065 82.46 1,137 <0.001
Leg tocopherol 2.752 0.605 20.73 1,137 <0.001
Liver tocopherol −1.469 0.544 7.28 1,138 0.008
Liver vitamin A −0.024 0.015 2.73 1,135 0.101
Total number of eggs −0.032 0.014 5.1 1,137 0.026
Total astaxanthin in the eye rings Carotenoid 51.64 3,146 <0.001
Diquat 1.47 1,151 0.227
Carotenoid × diquat 3.21 3,147 0.025
Sex 17.4 1,148 <0.001
Sex × carotenoid 3.21 3,146 0.025
Tocopherol in the eye rings 0.674 0.06 125.22 1,149 <0.001
Total number of eggs −0.004 0.002 6.54 1,145 0.012
Total papilioerythrinone in the eye rings Carotenoid 19.9 388.3 <0.001
Diquat 0.55 180.1 0.46
Sex 13.83 179.6 <0.001
Carotenoid × diquat 0.33 377.4 0.804
Sex × diquat 1.74 181.8 0.19
Sex × carotenoid 3.71 379.5 0.015
Fat retinol 0.032 0.031 1.04 1,136 0.309
Plasma tocopherol 0.3 0.182 2.71 1,140 0.102
Tocopherol in the eye rings 0.85 0.149 32.42 1,140 <0.001
Total number of eggs −0.007 0.004 3.03 183.8 0.086
Tocopherol in the eye rings Carotenoid 3.64 371.7 0.017
Diquat 1.22 175.7 0.272
Carotenoid × diquat 2.63 373.5 0.056
Total number of eggs −0.006 0.002 8.96 171.1 0.004
Total astaxanthin in the bill Carotenoid 141.3 3,151 <0.001
Sex 5.43 1,155 0.021
Diquat 4.68 1,157 0.032
Carrotenoid × diquat 2.67 3,155 0.049
Plasma tocopherol 1.176 0.061 371.2 1,158 <0.001
Total number of eggs −0.007 0.002 17.86 1,151 <0.001
Total papilioerythrinone in the bill Carotenoid 134.5 364.8 <0.001
Diquat 0.08 168.8 0.774
Sex 2.66 175.8 0.107
Carotenoid × diquat 1.76 366 0.163
Tocopherol in the bill 1.536 0.133 133.35 1,134 <0.001
Plasma retinol −9.373 4.689 4 1,140 0.048
Total number of eggs −0.009 0.003 9.17 173.4 0.003
Tocopherol in the bill Carotenoid 2.94 3,158 0.035
Diquat 3.91 1,162 0.05
Carotenoid × diquat 3.09 3,160 0.029
Sex 5.6 1,161 0.019
Total number of eggs −0.007 0.002 9.66 1,159 0.002
Total astaxanthin in the legs Carotenoid 7.36 392.1 <0.001
Diquat 0.13 178.8 0.7168
Sex 2.98 186.9 0.088
Carotenoid × diquat 0.07 376 0.974
Sex × diquat 0.14 176.6 0.712
Sex × carotenoid 0.56 374.3 0.645
Plasma tocopherol 0.146 0.113 1.66 1,144 0.199
Liver vitamin A 0.004 0.002 3.32 1,133 0.071
Fat retinol −0.032 0.018 3.19 1,130 0.077
Tocopherol in the legs 0.526 0.097 29.25 1,141 <0.001
Total number of eggs 0.003 0.002 1.37 187.5 0.244
Total papilioerythrinone in the legs Carotenoid 4.17 392.9 0.008
Diquat 0.61 184.9 0.436
Sex 6.93 191.3 0.01
Carotenoid × diquat 0.17 382.1 0.919
Sex × diquat 0.24 181.1 0.627
Sex × carotenoid 0.16 378.8 0.919
Tocopherol in the legs 0.867 0.147 34.64 1,143 <0.001
Liver vitamin A −0.003 0.004 0.49 1,144 0.484
Tocopherol in the legs Carotenoid 4.09 382.2 0.009
Diquat 2.4 183.8 0.125
Carotenoid × diquat 1.21 182.4 0.3126
Sex 5.98 189.5 0.016
Total number of eggs −0.004 0.002 4.41 182.1 0.039
Plasma lutein Carotenoid 151.01 3,149 <0.001
Diquat 0.01 1,149 0.925
Carotenoid × diquat 2.84 3,149 0.04
Lutein at day 48 0.446 0.062 51.81 1,149 <0.001
Plasma tocopherol 0.479 0.0326 215.52 1,149 <0.001
Eggs during diquat experiment −0.003 0.002 4.42 1,149 0.037
Plasma zeaxanthin Carotenoid 321.37 3,146 <0.001
Diquat 0.83 1,146 0.363
Carotenoid × diquat 1.57 3,146 0.2
Zeaxanthin at day 48 0.307 0.07 19.24 1,146 <0.001
Plasma tocopherol 0.572 0.039 219.4 1,146 <0.001
Fat tocopherol −0.037 0.013 8.24 1,146 0.005
Liver vitamin A 0.002 0.001 4.79 1,146 0.03
Eggs during diquat experiment −0.004 0.002 4.05 1,146 0.046
Plasma tocopherol Carotenoid 5.26 395.1 0.002
Diquat 2.72 182.3 0.103
Sex 0.14 186.2 0.71
Carotenoid × diquat 0.7 379.3 0.552
Sex × diquat 0.7 182.7 0.404
Tocopherol at day 48 0.199 0.069 8.31 1,139 0.005
Liver vitamin A −0.004 0.002 3.99 1,134 0.048
Fat retinol 0.03 0.016 3.34 1,138 0.07
Plasma retinol 0.259 0.162 2.57 1,141 0.111
Total number of eggs −0.003 0.002 2.21 184.2 0.141
Plasma retinol Carotenoid 1.36 380.5 0.262
Diquat 1.54 180.3 0.218
Sex 0.51 177.9 0.476
Carotenoid × diquat 0.51 377.7 0.678
Sex × diquat 0.31 178.7 0.579
Sex × carotenoid 0.64 379.5 0.589
Retinol at day 48 33.86 4.27 62.89 1,134 <0.001
Plasma tocopherol 5.209 1.95 7.13 1,140 0.009
Eggs during diquat experiment −0.258 0.095 7.34 173.6 0.008
Liver lutein Carotenoid 128.63 3,157 <0.001
Diquat 0.06 1,157 0.811
Carotenoid × diquat 1.49 3,157 0.22
Plasma tocopherol 0.075 0.036 4.45 1,157 0.037
Liver tocopherol 0.263 0.028 85.5 1,157 <0.001
Liver zeaxanthin Carotenoid 315.42 3,151 <0.001
Diquat 0 1,154 0.971
Carotenoid × diquat 3.06 3,151 0.03
Plasma tocopherol 0.1 0.046 4.69 1,151 0.031
Liver tocopherol 0.341 0.04 74.08 140.3 <0.001
Plasma retinol 0.003 0.001 3.6 1,153 0.06
Liver tocopherol Carotenoid 12.77 3,161 <0.001
Diquat 6.47 1,161 0.012
Carotenoid × diquat 2.76 3,161 0.044
Liver vitamin A Carotenoid 57.35 3,152 <0.001
Diquat 0.04 1,154 0.834
Sex 22.3 1,154 <0.001
Carotenoid × diquat 0.47 3,152 0.707
Sex × diquat 0.71 1,152 0.399
Plasma tocopherol −11.032 4.001 7.6 1,153 0.007
Liver tocopherol 10.309 3.538 8.49 155.8 0.005
Total number of eggs −0.394 0.07 31.26 1,152 <0.001
Fat lutein Carotenoid 12.87 3,147 <0.001
Diquat 0.06 1,148 0.808
Sex 0.13 1,147 0.716
Carotenoid × diquat 0.21 3,148 0.89
Sex × diquat 0.19 1,147 0.662
Sex × carotenoid 1.26 3,147 0.292
Fat tocopherol 1.288 0.181 50.69 1,142 <0.001
Liver vitamin A 0.022 0.01 4.62 1,147 0.033
Plasma retinol −0.039 0.016 5.77 1,147 0.018
Fat retinol 0.241 0.087 7.72 1,148 0.006
Fat zeaxanthin Carotenoid 46.74 3,148 <0.001
Diquat 0.16 1,148 0.687
Sex 0.28 1,147 0.598
Carotenoid × diquat 0.12 3,148 0.948
Sex × diquat 0.88 1,148 0.349
Sex × carotenoid 1.23 3,148 0.302
Fat tocopherol 0.911 0.15 37.07 1,129 <0.001
Liver vitamin A 0.019 0.01 4.55 1,148 0.035
Plasma retinol −0.023 0.014 3.01 1,148 0.085
Fat retinol 0.203 0.073 7.84 1,148 0.006
Fat tocopherol Carotenoid 0.57 395.7 0.638
Diquat 1.3 182.8 0.257
Sex 0.04 181.4 0.849
Carotenoid × diquat 0.15 382 0.931
Sex × diquat 0.31 181 0.578
Sex × carotenoid 1.71 379.4 0.171
Liver vitamin A 0.005 0.004 1.11 1,130 0.295
Plasma retinol −0.012 0.007 3.05 1,138 0.083
Total number of eggs −0.005 0.005 0.99 191.4 0.323
Fat retinol Carotenoid 29.11 3,149 <0.001
Diquat 0.18 1,148 0.671
Sex 0.14 1,147 0.706
Carotenoid × diquat 0.24 3,149 0.867
Sex × diquat 0.05 1,149 0.816
Sex × carotenoid 1.06 3,148 0.368
Plasma tocopherol 0.64 0.535 1.43 1,149 0.234
Liver tocopherol 0.136 0.428 0.1 1,149 0.752
Fat tocopherol −0.103 0.165 0.39 164.6 0.537
Total number of eggs −0.025 0.01 6.77 1,148 0.01
UA & ALB-corrected PLAOX Carotenoid 3.4 379.9 0.022
Diquat 0.37 171.4 0.543
Sex 1.61 369.7 0.209
Carotenoid × diquat 1.34 169.6 0.269
Carotenoid × sex 0.33 362.6 0.805
Diquat × sex 0.03 175.9 0.855
Carotenoid × diquat × sex 2.85 361.3 0.045
AOX at day 48 0.331 0.11 9.07 173.1 0.004
Fat tocopherol 0.054 0.03 3.21 1,103 0.076
Uric acid 0.056 0.005 119.03 1,101 <0.001
Albumin −0.009 0.005 3.73 1,104 0.056
Liver vitamin A −0.004 0.002 3.69 187.2 0.058
Eggs during diquat experiment −0.011 0.005 4.66 183.9 0.034
Plasma TRG-corrected MDA Carotenoid 0.29 3,139 0.836
Diquat 6.84 1,139 0.009
Sex 4.8 1,140 0.03
Carotenoid × diquat 0.86 3,139 0.466
Diquat × sex 4.45 1,140 0.037
TRG-corrected MDA at day 48 2.419 0.745 10.48 1,139 0.002
Triglycerides 0.004 0.001 36.4 1,140 <0.001
Eggs during diquat experiment 0.126 0.044 8.28 1,140 0.005
Liver MDA Carotenoid 1.27 388 0.289
Diquat 0.2 177.4 0.659
Sex 22.76 180.4 <0.001
Carotenoid × diquat 1.96 376.7 0.127
Carotenoid × sex 1.21 375 0.311
Diquat × sex 0.15 175.4 0.699
Carotenoid × diquat × sex 4.65 376 0.005
Liver vitamin A 0.0002 0.0001 7.07 1,138 0.009
Plasma tocopherol 0.0003 0.0001 3.73 1,139 0.055
Heart MDA Carotenoid 0.09 3,157 0.963
Diquat 0.95 1,157 0.331
Sex 2.75 1,157 0.099
Carotenoid × diquat 1.79 3,157 0.151
Erythrocyte resistance to oxidative stress Carotenoid 0.35 361.1 0.793
Diquat 5.66 161.1 0.021
Carotenoid × diquat 2.27 361.4 0.09
Lag time −0.229 0.035 44.06 1,121 <0.001

Note:

ALB, albumin; MDA, malondyaldehydes; PLAOX, plasma antioxidants; TRG, tryglycerides; UA, uric acid.