Predictive role of mitochondrial genome in the stress resistance of insects and nematodes |
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Authors: | Pandey Akshay Suman Shubhankar Chandna Sudhir |
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Institution: | Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road, Delhi -110054, India. |
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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. |
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Keywords: | mitochondrial genome codon bias stress resistance insects nematodes |
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