Characterising the Drosophila extracellular superoxide Dismutase gene

The indiscriminate action of reactive oxygen species (ROS), if left unregulated, has<br/>long been considered contributory to a range of disease processes within the animal<br/>kingdom and is also a factor associated with ageing. Consequently modifying the<br/>molecular mechanisms that regulate ROS levels may prove therapeutic and could also<br/>positively affect longevity. One of the key components of this machinery is the<br/>superoxide dismutase (SOD) family of enzymes which regulate ROS levels by<br/>scavenging the ROS superoxide. Mammals have three distinct SOD enzymes each<br/>responsible for managing superoxide levels in different cellular compartments. In<br/>Drosophila homologues of two of the mammalian SODs, the intracellular (SOD1) and<br/>mitochondrial (SOD2) SODs, have been identified and studied extensively<br/>demonstrating a clear link between SOD and oxidative protection and survival.<br/>Recently the sequence of a third sod gene, homologous to both the relatively poorly<br/>characterised mammalian (sod3) and C. elegans (sod-4) extracellular sod, was<br/>identified in Drosophila and is also predicted to locate extracellularly (sod3). To date,<br/>no (published) work has been carried out to assess the role of sod3 within insects. This<br/>thesis reports the molecular and biochemical characteristics of sod3 in Drosophila.<br/>Detailed within are the steps taken to clone the sod3 gene which appears to be<br/>expressed as two gene products formed by alternative splicing. Furthermore, a<br/>combination of gene expression, proteomic and functional analysis of a number of sod<br/>mutants was used to: i) reveal sex specific sod gene expression; ii) validate a sod3<br/>hypomorph mutant; iii) indicate a functional role for sod3 in protection against H2O2<br/>induced oxidative stress; iv) suggest a SOD1-SOD3 co-dependency for maintaining Cu<br/>Zn SOD activity; v) demonstrate the appearance of genetic modifiers in the sod3<br/>hypomorph. The findings of this report and further studies on the Drosophila sod3 gene<br/>should encourage the re-evaluation of the previous work concerning SOD’s influence<br/>on disease states and lifespan regulation.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2010

Author dc:creator

• Blackney, Michael James

Advisor dc:contributor.advisor

• Parker, Joel