Figure 2. Downregulation of crb can block neurodegeneration in the Aβ42 background.

TUNEL assays are commonly employed to mark the cells undergoing cell death where the cleavage of double and single stranded DNA is labeled by a Fluorescein [31]. (A) Wild type eye imaginal disc showing a few TUNEL positive nuclei. (B) Misexpression of Aβ42 using GMR-Gal4 driver [22] in the differentiating photoreceptor neurons results in induction of neurodegeneration (B) as seen by a three-fold induction of cell death as evident from number of TUNEL positive nuclei of the dying cells in comparison to (A) wild type eye imaginal disc. Misexpression of Crb full length (FL) in GMR>Aβ42 background (GMR>Aβ42+Crb FL) strongly enhances (C) the neurodegeneration phenotype which results in nearly seven fold increase in number of TUNEL positive nuclei of dying cells in comparison to wild type eye imaginal disc. (D, E) Reducing Crb levels by using (D) crb^11A22 mutant allele [33] (GMR>Aβ42+crb^11A22) or (E) crb RNAi (VDRC) (GMR>Aβ42+RNAi) result in the rescue of GMR>Aβ42 mediated neurodegeneration as evident from reduction in numbers of TUNEL positive nuclei of the dying cells. (F) Quantitatively, the number of TUNEL cells have been counted and recorded with all five constructs shown. These phenotypes of enhancement of neurodegenerative phenotype and rescue, based on the number of TUNEL positive cells, are significant as seen by the calculation of P-values based on the one-tailed t-test using Microsoft Excel 2010.