Blimp-1 Participates in Patterning during Pupal Eye Development. Carrie L Jenkins¹, Gerald B Call². 1) Biomedical Sciences, Midwestern University, Glendale, AZ; 2) Dept. of Pharmacology, Midwestern University, Glendale, AZ.

   B lymphocyte-induced maturation protein (Blimp-1) was identified in Drosophila melanogaster nearly 7 years ago, but its function is still largely unknown. Mosaic eye tissue (generated from the ey-Flp/FRT system) reveals a unique raised glossy lens surface in mutant tissue in adults and significant interommatidial bristle patterning defects in both adults and pupae. Staining larval eyes with various developmental markers indicates normal development up until this stage. However, data from staining pupal eye discs reveals that the Blimp-1 mutation leads to nonautonomous ommatidial patterning defects including loss and mispatterning of bristles (64% vs. 2% in control eye discs) and secondary pigment cells (17% vs. 0%), but not in tertiary pigment cells. Cone cells are still being analyzed. Current analysis of cell adhesion molecules essential to ommatidial patterning in Blimp-1 mosaic eye tissue is underway to determine mechanisms behind this mispatterning. To further investigate the adult raised glossy eye phenotype the interaction between Blimp-1 and Crystallin, the main lens protein, is being studied through the use of Cry-lacZ reporters. When raised at 25C, normal Cry-lacZ expression begins in primary pigment cells (PPC) sporadically distributed throughout the eye disc at about 35-40 hours after puparium formation (APF), and slowly ramps up into full production in all PPCs and cone cells (CC) by 45-50 APF, and then ceases by 65 APF. In striking contrast, by 35 APF at 25C, all photoreceptors (R) strongly express Cry-lacZ, and continue to do so through 50 APF in mosaic Blimp-1 eye discs in a non-autonomous manner. At 35APF, all PPCs and some CCs in Blimp-1 mosaic eye discs show premature Cry-lacZ expression in a non-autonomous pattern. However, at 50-55 APF, PPCs appear to maintain a higher expression level of Cry-lacZ in the Blimp-1 mutant cells. This autonomous misexpression pattern of Cry-lacZ might explain the raised lens phenotype observed in the adult mosaic eyes. These findings suggest that Blimp-1 regulates multiple pathways involved in late eye development.