Figure 1. Survivin gene and protein and proliferating cell nuclear antigen (PCNA) protein expression in the chicken embryo lens. A: QPCR for Survivin mRNA expression during lens development revealed that Survivin mRNA was maximal at ED6 followed by dramatic downregulation at ED8 onwards. All stages except ED10 were statistically significantly different regarding the calibrator (ED12) to which all samples were normalized (*=p<0.05). B-C: Survivin and PCNA protein expression in the lens were analyzed between ED6 and ED20 (representative western blots are shown). ED12 was used as the calibrator to which all other stages were compared. B: There was a statistically significant decrease in Survivin expression from ED8 onwards, and all stages were significantly different regarding the calibrator (ED12; *=p<0.05; n=3) C: PCNA (35 kDa) expression was detected at all stages, but was downregulated as lens development proceeded. With the exception of ED10, statistically significant differences were found between the expression levels of PCNA at all stages compared to the calibrator ED12 (*=p<0.05; n=3). Chicken embryo brain (ED6) was used as positive control C+ in each case. Protein expression was quantified with densitometry using the scan program and normalized with respect to β-actin protein (n = 3) as a housekeeping control. Error bars represent the standard error of the mean. au=arbitrary units for relative levels of expression.