Shcherbakova O. Genetic analysis and behavioral reactions of Drosophila melanogaster mutants with degenerative changes in the brain tissue

We have performed a saturation mutagenesis screen with ethyl methane sulphonate, obtained neurodegenerative mutants of D. melanogaster on the third chromosome and studied the morphological and functional changes in their brain tissue. Using the complementation test mutants were divided into the five groups which differed also by special degenerative phenotype. Obtained stocks were characterized by reduced mean and maximum lifespan, age-dependent neurodegeneration and behavioural deteriorations. There were stocks with decreased or increased reproductive activity and reduced moving ability. The analysis of neurodegenerative mutants' resistance to hyperoxia treatment showed that flies 4.14.10 were sensitive to oxidative stress. These mutants exposed to hyperoxia developed an unusual phenotype that was not seen in any previously identified neurodegenerative mutants and not in mutants 4.14.10 after normal conditions. Light and electron microscopy of mutant brain tissue showed derangement of eye tissue and eye basal membrane, swelling of lamina ganglion cells and glia in the lamina cortex. Complementation test discovered the allelism of 4.14.10 and loechrig mutations and respectively, their localization in the SNF4Agamma gene. Detection of brain tissue of another mutant stock, 3.5.8 revealed cells with the features of apoptosis and neurons that were enwrapped by multilayered glial membranes.Mutation 3.5.8 was localized in the region 62B7-70D3 of the third chromosome. Neurodegenerations of 4.14.10 and 3.5.8 mutants were accompanied also by derangements in phototactic and locomotor behavior.