Snapshots for intra- and inter-ocular differences at retinal proteins levels

We attempted to study the intra- and inter-animal variations of protein expressions in chick retina using two-dimensional electrophoresis (2-DE). The posterior retinas of 10 day-old chicks were harvested. The proteins were extracted and 2-DE protein profiles between two eyes of the same individual and among different animals were compared and analysed using Melanie gel analysis software. Computerised Melanie gel analysis showed a high similarity of 83.1 ± 2.1% (mean ± SEM, n=3) between the protein profiles of right and left retinas from the same animal. However, this percentage dropped to 64.1 ± 3.1% (Mean ± SEM, n=3) when comparing between different animal samples. We have shown that there were good similarities in intra-animal comparison but poor in inter-animal comparison. We have documented the caveat in comparing the protein profiles between different animals where apparent differentially display protein could actually be a false positive signal. The finding highlighted the potential usefulness of the proteomic approach in basic eye research where comparison between control and experimental tissues could be carried out in the same animal, rather than using different animals.