Affect of heavy metal induced oxidative stress tolerance on energy metabolism in Drosophila melanogaster Geetanjali Sageena Evolutionary Biology Laboratory Department of Zoology University of Delhi New Delhi-110007

Background Industrialization and urbanization has resulted in environmental pollution. Various Heavy metals are adding to environmental load due to higher rate of persistence and accumulation. Results in oxidative stress. Persistent imbalance between antioxidants and pro-oxidants causing irreversible cellular damage. Adaptive physiological mechanisms aid in increased survival which plays an important role in evolution and adaptation of living organisms. WITH THE ADVENT OF INDUSTRALIZATION

www.anatomy.unimelb.edu.au/.../life_cycle.jpg 22-24 h ~ 24 h ~ 48 h ~ 110 h

Fly maintenance Pre Adult Duration 9½ days Lifespan 30 Days

Control Selected Resource Rich Short Lifespan Resource Deficient Long Lifespan

Adult flies are housed in Plexiglas cages (25 x 20 x 15 cm3) Banana-jaggery food is provided in petridish and changed every alternate day. Populations kept at standard laboratory conditions (SLC).

Aims and Objectives To check the effect/affect of two chemical stressors (Heavy Metals) namely FeSO4 and CdCl2 on L1 to adult development. Estimation of major energy reserves in both stressed and non stressed condition

Running Stock Cultures Methodology Running Stock Cultures Standardized Flies Eggs used for assay CONTROL (JBs) Two types of fly populations Heavy Metal Conc. SELECTED (FLJs) YEAST SM 1 SM + 13 mM FeSO4 Sync Eggs 2 SM + 5µM CdCl2 3 4

Transferred to chemical treatment Synchronized Eggs Post 22 hours L1 Transferred to chemical treatment L1 to adult development time. Estimation of major energy reserves i.e. Lipids, Proteins and Carbohydrates by Ether, BCA and Anthrone method respectively Estimation of Energy accumulation per unit time. 4.2 cal/mg CARBOHYDRATES 4.19 cal/mg PROTEINS 9.5 cal/mg LIPIDS (Platt and Irwin 1973)

RESULTS developmental Time

Lipid content

PROTEIN content

carbohydrates content

energy accumulation/ time Treatment F2,4 = 16.107, p = 0.01 the combined results of development time and energy accumulated per unit time clearly evidenced that the FeSO4 although is an essential HM, might be docking some of the sites resulting in the failure of system to recognize it as harmful, while the system might be effectively neutralizing CdCl2 as it is a foreign particle for the system that is otherwise not present and hence there is more accumulation of energy in case of CdCl2 supplemented medium. It can also be speculated that in latter case energy accumulation is more as flies might have increased the food intake when reared on the cadmium supplemented medium in order to meet the energy requirement and in the former case (iron supplemented medium) flies might be having aversion towards the characteristic fragrance of iron and hence might have reduced the food intake, it is well known that chemosensory receptors in D.melanogaster are extremely sensitive to external environmental cues (Hallem and Carlson, 2004).

CONCLUSIONS Larval growth slowed when reared on heavy metal supplemented diet. Increased development time did not result in the increased macromolecular accumulation among the flies. Slowing down of the metabolic processes, or a greater utilization of energy reserves during metamorphosis or both. Bioenergetics play a crucial role in regulation of Oxidative stress. Positive relation between energy reserve and stress tolerance. Whereas stress tolerance and lifespan are not tightly correlated. Females more tolerant than males.

Laboratory Assistance: Sahil Malhotra Acknowledgements My Supervisor Dr. Mallikarjun Shakarad Funding agency CSIR &DU Experimental Work: Mr. Rakesh Roshan Ms Shreya Choudhary Ms Nalini Mishra Laboratory Assistance: Sahil Malhotra

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