Water fowl such as ducks and geese are included in the diets of human. Water fowl that eat fish are higher on the food chain strata than those that eat plants or insects like geese. Contaminants like organic and inorganic pollutants (insecticides, herbicides and radioactive metals) ultimately reach water resources and build up in the fat tissue of aquatic fauna, are a concern to the health of water fowl. Contaminants become more concentrated when predators eat prey leading to bio magnification within the body system.

At high levels, radiations can cause cell damage and even cancer. Ionizing radiation inflicts deleterious effects by damaging cellular DNA and membrane(Weiss and Landauer, 2003). Little information is available about effects of low levels of radiations in health aspects of water fowl.

Several plant compounds are reported to have radioprotection properties (Arora et al., 2005).Curcumin (Diferuloyl methane) is the principle curcuminoid of popular Indian spice turmeric; member of ginger family (Zingiberaceae). Curcuminoids are polyphenols, which impart yellow colour to rhizomes of Curcuma longa. Curcumin has been extensively studied for its anti-oxidant, antiinflammatory(Menon and Sudheer, 2007) and anticancer(Jagetia and Aggarwal, 2007) properties.However its radio protective potential has not yet been exploited in the veterinary field.

Alkaline comet assay is a sensitive technique to monitor strand breaks and alkali labile DNA lesions and rightly used to study genotoxicity, cellular DNAlesions, apoptosis and DNA repair (Olive, 1999).The present study is focused to find on the DNAprotecting ability of curcumin in Kuttanad ducks by adopting comet assay, which is considered to be a rapid and sensitive method for detection of primary DNA damage at the single cell level.

The study was performed on healthy adult female Kuttanad ducks; six months age; procured from University Poultry Farm, KAU, Mannuthy.These ducks were grouped (6 / group) into G I:untreated and non irradiated, G II: Untreated and irradiated, G III: treated with curcumin @40mg/kg body wt. and irradiated and G IV: administered with Dimethyl sulfoxide (DMSO) intravenously and irradiated.

Required quantity of curcumin (40 mg/kgbody weight) was dissolved in 500μL of DMSO and given by slow intravenous route through saphenous vein to G III and 500μL of DMSO alone to G IV birds. Blood was collected (3ml) in anticoagulant,dipotassium EDTA, from all birds of G I and G II, but after 20 min of intravenous administration of curcumin from G III and of DMSO from G IV.Whole blood samples from untreated (G II),curcumin treated (G III) and DMSO alone administered (G IV) which were exposed to 0.5GyGamma radiation, were named as G IIA, G IIIA and G IVA respectively. Those blood samples from untreated, curcumin treated and DMSO alone administered exposed to one Gy Gamma radiation were considered as G IIB, G IIIB and G IVB respectively.

The alkaline comet assay (Singh, 2000) was used to access the effect of irradiation on cellular DNA and for any protective effect of curcumin on DNA damage. In short, the comet assay was conducted in alkaline medium on frosted slides coated with agarose. Precoating of slides was done with normal melting point agarose (1% in PBS: pH 7.4). Immediately coversliped and kept at 40C for 10min to get the agarose solidified. After removal of coverslip, 200 μL of 0.8% low melting point agarose containing 5 μL of whole blood, was added to the slide. Cover slips were placed immediately and slides were kept at 4oC for 10 min. After solidification cover slips were removed and slides were immersed in prechilled lysing solution containing 2.5M NaCl, 100mM Na EDTA, 10mM 2 Tris-HCl; pH-10, 1% DMSO, 1% Triton X and kept for 1 hour at 4oC. After lysis , slides were drained properly and placed in a horizontal electrophoresis apparatus filled with freshly prepared electrophoresis buffer containing 300mM NaOH,1mM EDTA and 0.2% DMSO; pH > 13. The slides were equilibrated in buffer for 20 min and electrophoresis was carried out for 30 min at 25 V.The slides were washed gently with 0.4mM Tris-HCl buffer, pH-7.4 to remove alkali. The slides were again washed with distilled water. One per cent propidium iodide was used for staining the gel and comets were visualized under fluorescent microscope with 40X magnification. The images were captured and analyzed using software 'CASP' which gives % DNA in tail, tail DNA length, tail DNA moment and olive tail DNA moment directly. The tail moment (TM) was an index calculated from tail length and % DNA in tail and olive tail moment (OTM) as the product of the distance between the centre of gravity of the head and the centre of gravity of the tail and % DNA in tail.

Statistical analysis was carried out to find out any significant difference between untreated and treated groups when compared to normal group, using student 't'test.

Exposure of duck blood cells to Gamma radiation ex-vivo induced damage to cellular DNA as evident from the comet formation. Exposure of blood cells to one Gy resulted in a significant (P<0.05)increase in comet parameters such as % DNA in tail(from 11.0+1.2% to 30.8+4%) (Fig 1.), tail DNA length(from 19.4+2.5μm to 112.0+15.8μm)( Fig 2.), tail DNAmoment (from 2.2+0.4 to 40.1+8.6) (Fig 3.) and olive tail DNA moment (from 5.4+0.9 to 27.9+4.7) (Fig 4.) in untreated (G IIB) when compared to normal (G I) blood samples. However, blood samples exposed to 0.5 Gyradiation (G IIA) exhibited significantly (P<0.05)lesser comet parameters such as % DNA in tail(24.9+4%), tail DNA length (79.4+4.4μm), tail DNAmoment (20.4+3.4) and olive tail DNA moment(18.8+3.1) when compared to one Gy exposed samples.There was significantly (P<0.05) lesser damage of DNA, induced by 0.5 Gy (G IIIA) and one Gy (G IIIB)irradiated blood collected from curcumin treated ducks as evident by the comet parameters like % tail DNA19.4+3.4% and 22.6+2.4%, tail DNA length 33.2+3.9μm and 40.0+5.5 μm, tail DNA moment 6.2+0.9 and 9.2+2.1 and olive tail DNA moment 9.7+1.9 and11.7+1.5 respectively.

Similarly blood samples exposed to 0.5Gyradiation of DMSO alone administered birds (G IVA)exhibited significantly (P<0.05) lesser comet parameters such as % DNA in tail (24.2+1.8%), tail DNA length(79.0+6.1μm), tail DNA moment (12.3+0.9) and olive tail DNA moment (14.7+2.0)

when compared to one Gy exposed samples (GIVB).The corresponding values obtained in GIVB birds were 28.8+2.9 as % DNA in tail,84.0+10 μm as tail DNA length, 18.78+2.9 as tail DNA moment and 20.3+0.8 as olive tail DNA moment.

Ionizing radiations like X-rays and Gamma rays, beta particles, alpha particles and neutrons are known to induce oxidative stress due to Reactive Oxygen Species (ROS) production within cells,resulting in imbalance of the pro-oxidant and antioxidants in the cells which ultimately leads to cell death. Major damages due to ionizing radiation are single strand breaks, double strand breaks, DNADNA and DNA-protein cross links and damages to nucleotide bases. Overproduction of ROS, thus leads to mutation and chromosomal aberrations.Radiation induced loss of viability of cells has been attributed to unrepaired lesions in DNA. Thiol compounds such as amifostine, phosphonol, Nacetyl-L-cysteine, captopril and mesna have been shown to exhibit antioxidant properties and reduce radiation damage in DNA (Kataoka et al., 2007)