Expression analysis of chicken chorioretinal tissues in control and myopic eyes with or without violet light

To find the possible molecular mechanism of myopia protection by violet light, we performed expression microarray analysis of chick chorioretinal tissue. The mRNA were obtained at day 13 from the following four groups: control eyes with or without violet light exposure and covered eyes with or without violet light exposure, and then the gene expression pattern was compared among them. Principle component analysis, which is to find major patterns of variability in gene expression, was performed and we found that the largest gene population (PC1, positive: n = 138, negative: n = 292) was affected by violet light treatment. On the other hand, the second largest gene population (PC2, positive: n = 120, negative: n = 23) was affected in the eyes covered with a plastic lens. The previously reported myopia-related genes such as Bmp2, Ednrb, Fgf2, Igf1, Il18, Irbp, Lumican, Sfrp1, Tgfb1, Vegfa, Vip, and Wnt2b were not found in the PC1 group in vivo, which indicates that they responded less to violet light. In the PC1 group, only one myopia protective gene, EGR1 (ZENK, zif268), was found among the previously reported myopia related genes. Sixteen eyeballs of eight chicks from the two experiment groups were divided into four subgroups: violet-/control, violet+/control, violet-/covered, violet+/covered. Total RNA of the four eyeballs in each subgroup were extracted and mixed. Total RNA was analyzed using Chicken (V2 026441) Gene Expression Microarray 4 x 44K (Agilent 153 Technologies, California, USA).