Meeting Abstract
The proteins in the lens that contribute to transparency and light refraction are crystallins. These proteins have an interesting and complicated evolutionary history with surprising diversity across closely related taxa. Many of these proteins have secondary functions as metabolic enzymes and heat shock proteins. Even more unusual, crystallins α, β and γ are common in vertebrates but individual taxon-specific crystallins have been identified as well. One of the most remarkable examples is the high abundance of lactate dehydrogenase B in the duck lens, designated ε-crystallin, is lacking in the chicken lens. Since this discovery in 1985, progress towards a phylogenetic understanding of lens protein content and evolution has been slow due to the difficulty of performing large-scale protein analysis across species. Recent advances in proteomic methods and the availability of whole-genome sequences now enable our ability to perform broad, cross-species protein content analysis to better understand crystallin protein diversity and lens evolution. Lenses from a phylogenetically diverse sample of bird species were acquired for proteomic analysis. The tissue was analyzed for protein identity and relative abundance using both in-solution and gel-band extraction sample preparations followed by shotgun mass spectrometry. Protein abundances were quantified by normalized spectral counts and integrated ion intensities. Genomic regions surrounding genes identified in the lens proteomics studies were found in the corresponding bird species and comparative sequence analysis was performed. We see significant lens protein content diversity across species as well as differences in relative abundances. These results provide a better phylogenetic understanding of the diversity and unusual regulatory history of crystallin proteins in the bird lens.
