GnRH-I mRNA expression in pineal gland between LL and SL chickens at D112 and D136. (a) Representative electrophoresis photo of RT-PCR products for GnRH-I and β-actin mRNA, respectively. M: DNA molecular weight marker DL2000. LL and SL lanes stand for long-light and short-light, respectively. (b) Results of statistical analysis for GnRH-I mRNA level expressed as arbitrary units relative to β-actin mRNA. The results were expressed as mean ± S.E.M and differences were considered significant when P < 0.05 tested by ANOVA with SPSS 11.0 for windows. Mean values with (a, b) differ significantly between LL and SL groups (P < 0.05, n = 10).