In Drosophila melanogaster oxidative stress (OS) decreases lifespan and motor function (Coulom & Birman, 2004; Hosamani, 2013) through degeneration of dopaminergic (DA) neurons (Brooks et al., 1999). The mitogen-activated protein kinases, P38, c-JUN-NH2 terminal kinase (JNK) and extracellular-signal related kinase (ERK) are activated in response to OS (Apel & Hirt, 2004). My thesis investigated the protective role of up-regulation of the antioxidants superoxide dismutase (Sod) and catalase (Cat) in the glia of Drosophila against oxidative stress induced by paraquat (PQ). Exposure to PQ killed ~20-80% of flies and impacted motor functions as measured in a negative geotaxis assay. Pan-glial expression of Sod2 using Repo-GAL4 did not reduce the lethality caused by PQ exposure. These flies displayed a marked reduction in locomotion even when not exposed to PQ. However, their motor functions were not affected by PQ exposure. Pan-glial expression of Cat was not sufficient to prevent the negative effects of PQ exposure (viability and locomotion). Pan-neuronal expression of Sod2 using Elav-GAL4 protected the locomotive ability but not the lethality caused by PQ exposure. Pan-neuronal up-regulation of Cat protected against both the lethality and motor defects caused by PQ exposure. Over-expression of Sod2 and Cat in all sub-perineurial glial (SPG) cells using NP2276-GAL4 protected the motor function from exposure to PQ. Up-regulation of Sod1 and Sod2 in the SPG cells that form the blood brain barrier (BBB) using Spg Moody-GAL4 protected the motor function but not the lethality caused by PQ exposure. Over-expression of Sod2 in the SPG cells that form the BBB protected DA neurons from the deleterious effects of PQ exposure. A cluster of DA neurons, the paired posterior lateral 1 (PPL1), was identified as important for motor function. In both the parental lines and in flies in which Sod2 was up-regulated at the SPG cells, phospho-JNK and phospho-ERK were detected after 1h, 6h and 24h of PQ exposure by Western blot. Phospho-P38 levels were markedly reduced after 24h exposure to PQ in the parental controls. During all time points of PQ exposure, phosphorylated form of P38 was detected when Sod2 was up-regulated at the BBB. In conclusion, up-regulation of Sod2 in the SPG cells forming the BBB protects DA neurons from PQ exposure, maintains the phosphorylation status of P38, which may ultimately translate into protection of the motor function. It is possible that increased Sod2 expression at the BBB sustains phospho-P38 levels which may play a role in increasing the tolerance of the flies to oxidative stress induced by PQ. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16594 |
| Date | 06 1900 |
| Creators | Iftekharuddin, Nadia |
| Contributors | Campos, Ana R., Biology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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