Meeting Abstract
Complex visual function relies on the ability to properly focus light onto the retina. Arthropods exhibit a wide range of eye types, yet little is known about how the lenses from these animals are composed. One hypothesis is that highly sophisticated eyes with high acuity vision develop/require more complex lenses than do simple eyes with lower resolution. To test this hypothesis, we performed mass spectrophotometry and transcriptome analysis from the lenses of two distinct arthropod visual systems: the adult compound eye of Drosophila melanogaster and the bifocal lens from the sophisticated principal larval eyes of Thermonectus marmoratus, an effective visually guided predator which simultaneously focus two images onto two retinas. In both species, the main constituents of the lenses were co-opted genes from the cuticular protein family. However, in Drosophila, only 4 lens proteins were identified, while in Thermonectus, 11 were defined. In situ hybridizations of these genes revealed differential expression within the lens producing (corneagenous) cells in both species. Most notably, however, the expression patterns in Thermonectus suggest that the composition of lens proteins differs between the periphery and the center of the bifocal lens, a distribution consistent with our functional studies that suggest that the periphery of the lens is optically different from its center. This study illustrates that a more complex lens is formed by a larger number of proteins than a simpler lens, and provides an example in which an extraordinary lens has evolved by altering expression patterns of genes.
