Title

Authors

Akshay Pandey, Shubhankar Suman, Sudhir Chandna*

Affiliation

Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road, Delhi -110054, India

Email

sudhirchandna@yahoo.com; * Corresponding author

Article Type

Hypothesis

Date

received March 30, 2010; accepted April 09, 2010; published June 24, 2010

Abstract

Certain insects (e.g., moths and butterflies; order Lepidoptera) and nematodes are considered as excellent experimental models to study the cellular stress signaling mechanisms since these organisms are far more stress-resistant as compared to mammalian system. Multiple factors have been implicated in this unusual response, including the oxidative stress response mechanisms. Radiation or chemical-induced mitochondrial oxidative stress occurs through damage caused to the components of electron transport chain (ETC) leading to leakage of electrons and generation of superoxide radicals. This may be countered through quick replacement of damaged mitochondrial proteins by upregulated expression. Since the ETC comprises of various proteins coded by mitochondrial DNA, variation in the composition, expressivity and regulation of mitochondrial genome could greatly influence mitochondrial role under oxidative stress conditions. Therefore, we carried out in silico analysis of mitochondrial DNA in these organisms and compared it with that of the stress-sensitive humans/mammals. Parameters such as mitochondrial genome organization, codon bias, gene expressivity and GC3 content were studied. Gene arrangement and Shine-Dalgarno (SD) sequence patterns indicating translational regulation were distinct in insect and nematodes as compared to humans. A higher codon bias (ENC<35) and lower GC3 content (<0.20) were observed in mitochondrial genes of insect and nematodes as compared to humans (ENC>42; GC3>0.20), coupled with low codon adaptation index among insects. These features indeed favour higher expressivity of mitochondrial proteins and might help maintain the mitochondrial physiology under stress conditions. Therefore, our study indicates that mitochondrial genome organization may influence stress-resistance of insects and nematodes.

Keywords

mitochondrial genome, codon bias, stress resistance, insects, nematodes

Citation

Pandey, Bioinformation 5(1): 21-27 (2010)

Edited by

P. Kangueane

ISSN

0973-2063

Publisher

Biomedical Informatics

License

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. This is distributed under the terms of the Creative Commons Attribution License.