Quantifying Drosophila melanogaster Eye Phenotypes: A Computational Approach Integrating ilastik and Flynotyper.

The Drosophila melanogaster compound eye is a well-structured and comprehensive array of around 800 ommatidia, exhibiting a symmetrical and hexagonal pattern. This regularity and ease of observation make the Drosophila eye system a powerful tool to model various human neurodegenerative diseases. However, ways of quantifying abnormal phenotypes, such as manual ranking of eye severity scores, have limitations, especially when ranking weak alterations in eye morphology. To overcome these limitations, computational approaches have been developed such as Flynotyper. The use of a ring light allows for better qualitative images accessing the intactness of individual ommatidia. However, these images cannot be analyzed by Flynotyper directly due to shadows on ommatidia introduced by the ring light. Here, we describe an unbiased way to quantify rough eye phenotypes observed in Drosophila disease models by combining two software, ilastik and Flynotyper. By preprocessing the images with ilastik, successful quantification of the rough eye phenotype can be achieved with Flynotyper.

Eip74EF is a dominant modifier for ALS-FTD-linked VCPR152H phenotypes in the Drosophila eye model.

OBJECTIVES: In 2012, Liu et al. reported that miR-34 is an age-related miRNA regulating age-associated events and long-term brain integrity in Drosophila. They demonstrated that modulating miR-34 and its downstream target, Eip74EF, showed beneficial effects on an age-related disease using a Drosophila model of Spinocerebellar ataxia type 3 expressing SCA3trQ78. These results imply that miR-34 could be a general genetic modifier and therapeutic candidate for age-related diseases. Thus, the goal of this study was to examine the effect of miR-34 and Eip47EF on another age-related Drosophila disease model. RESULTS: Using a Drosophila eye model expressing mutant Drosophila VCP (dVCP) that causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), or multisystem proteinopathy (MSP), we demonstrated that abnormal eye phenotypes generated by dVCPR152H were rescued by Eip74EF siRNA expression. Contrary to our expectations, miR-34 overexpression alone in the eyes with GMR-GAL4 resulted in complete lethality due to the leaky expression of GMR-GAL4 in other tissues. Interestingly, when miR-34 was co-expressed with dVCPR152H, a few survivors were produced; however, their eye degeneration was greatly exacerbated. Our data indicate that, while confirming that the downregulation of Eip74EF is beneficial to the dVCPR152HDrosophila eye model, the high expression level of miR-34 is actually toxic to the developing flies and the role of miR-34 in dVCPR152H-mediated pathogenesis is inconclusive in the GMR-GAL4 eye model. Identifying the transcriptional targets of Eip74EF might provide valuable insights into diseases caused by mutations in VCP such as ALS, FTD, and MSP.