CORNEAL LENS SECRETION IN NEWLY EMERGED DROSOPHILA-MELANOGASTER EXAMINED BY ELECTRON-MICROSCOPE AUTORADIOGRAPHY

Drosophila corneal lens secretion was studied by electron microscope a utoradiography of [H-3]amino acids (leucine, lysine, phenylalanine, pr oline and tyrosine) and [H-3]sugars (glucosamine and mannose) in newly emerged flies. Ommatidial lenses were homogeneously labelled with bot h tracers at low levels, suggesting that lens materials turn over cont inuously after lens formation is completed. In contrast, ocellar lense s were heavily labeled, indicating that deposition of ocellar lens cut icle is still active at this stage. [H-3]amino acids and [H-3]sugars w ere deposited in distinct patterns in ocelli. Although over 90% of [H- 3]sugars remained, even 3 h after application, within 1 mu m of the ap ices of corneagenous cells associated with lens bases, [H-3]amino acid s distributed diffusely. There was an obvious gradient of [H-3] sugars from center to periphery of the lens base, suggesting that structure of the corneal lens in dorsal ocelli is determined by spatially regula ted secretion of chitin by corneagenous cells.