Ontological changes in the crystallin composition of the eye lenses of theterritorial damselfish Parma microlepis and their possible effects on trace-metal accumulation

The eye lenses of Parma microlepis from the rocky barrens of Sydney (New So uth Wales, Australia) were found to contain Ba, Hg, Rb, and Sr at concentra tions above the quantitative detection limits of solution-based inductively -coupled plasma-mass spectrometry (ICP-MS). Lenses were separated into the hard central nucleus and the softer surrounding cortex. Nuclei contained lo wer (equal for Ba) concentrations of these metals. Biochemical analysis of the protein composition of these lenses revealed differences in the ratio o f gamma-crystallin to beta-crystallin in the lens nucleus and cortex. These changes were shown to be attributable both to protein degradation and chan ges in protein synthesis as fish age. Such changes may lead to the loss of sequestered metals from older cell layers, or change the affinity of new la yers for particular trace metals. Differential binding affinities of these crystallins may, therefore, partially account for trace-metal differences o bserved in the lens nucleus and cortex.