Crystallin distribution patterns in the eye lens

• Main Author: Keenan, Jonathan
• Published: University of Ulster 2010
• Subjects: 611.84
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.554261

The lens is an ideal tissue to study growth and ageing since it continually grows throughout life accumulating cells with no protein turnover. The lenticular structural proteins, the crystallins, are distributed in layers that follow a chronological pattern. In this thesis, crystallin distribution patterns were investigated in concentric fractions of eye lenses from nine species. Clear lenses were used in order to examine changes occurring with development and ageing without the confounding factor of cataract. For the majority of species studied this was the first study to investigate and identify lens crystallin distributions. Lens proteins were separated using a fractionation technique following the lenticular growth mode. Individual crystallin subunits were further isolated and identified by size-exclusion chromatography, electrophoresis and mass spectrometry. Proportions of HMW, MMW and LMW proteins across each lens were determined by Bradford Assay. a, ~ and y-crystallin subunits were identified in each lens studied with comparable distribution patterns in phylogenetically similar species. a-crystallin proportions decreased from lens periphery to centre in all species and was not detected in the centre of amphibian and fish lenses. y-crystallins represented the most prominent soluble proteins in the lens centre with largest increases from the lens periphery seen in amphibian and fish, corresponding to their high refractive indices. Insoluble protein proportions increased towards the lens centre in all species. Taxon-specific crystallins were not identified in any species studied. Protein distribution patterns affect the optics of the lens; this structure/function relationship is important in understanding lens transparency. Protein distribution patterns in transparent lenses from in this thesis will assist understanding of changes in lenticular biochemistry taking place when transparency is compromised by cataract formation. Results from this thesis will also aid determination of phylogenetic relationships among species studied.