Endosulfan causes DNA damage in animals: Indian Researchers

 Endosulfan causes DNA damage in animalsCurrent Affairs : For the first time, researchers in India have found that mice and rats exposed to endosulphan suffer from DNA damage and genomic instability, and impaired DNA damage response.
The results published on August 4 in the journal, Carcinogenesis, by a team of researchers led by Prof. Sathees Raghavan from the Department of Biochemistry, IISc, Bengaluru show that endosulfan — an organochlorine pesticide — induces breaks in DNA strands and disturbs the damage response mechanism found in cells thus leading to compromised DNA strand repair.
Broken strands
  • Endosulfan also increased the damage by promoting erroneous repair of the broken DNA strands. Erroneous repair would lead to undesirable genome level changes leading to genomic instability, which may cause cancer and genetic abnormalities.
  • One of the major mechanisms by which broken DNA strands are repaired is through non-homologous end joining (NHEJ).
  • There was no difference in the rate at which both control animals and endosulfan-treated mice repaired broken strands using this mechanism. However, in endosulfan-treated mice and rats, there was enhanced activity of an error-prone and harmful repair mechanism (microhomology mediated end joining — MMEJ).
Sub-lethal doses used
  • Five animals per group were studied and the experiment was repeated many times. Three different concentrations of endosulfan were tested on animals and four doses of each concentration were given at 24 hours interval.
  • Even the highest dosage of 3 mg per kg of body weight used in the experiments is well below the lethal concentration (capable of killing 50 per cent of treated animals) of 12 mg/kg body weight.
  • Lungs and testes of the animals were used for the study. These two organs show very proficient DNA repair mechanism.

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