Radioresistance

Radioresistance is the property of organismswhich are capable of living in environments with very high levels of ionizing radiation, such as around nuclear power plants, or near natural uraniummineral sites.

Radioresistance is surprisingly high in many organisms, in contrast to previously held views. For example, the study of environment, animals and plants around the Chernobyl accidentarea has revealed an unexpected survivalof many species, despite the high radiation levels. A Brazilianstudy in a hill in the state of Minas Geraiswhich has high natural radiation levels from uranium deposits, has also shown many radioresistant insects, wormsand plants.

Radiation can also help some plantsto become more adapted to their environment by increasing the growth rateof the seeds. This helps them germinatefaster.

Induced radioresistance

Radioresistance may be induced by exposure to small doses of ionizing radiation. Several studies have documented this effect in yeast, bacteria, protozoa, algae, plants, insects, as well as in in vitro mammalianand human cells and in animal models. Several cellular radioprotection mechanisms may be involved, such as alterations in the levels of some cytoplasmaticand nuclearproteinsand increased gene expression, DNA repairand other processes.

Inheritance of radioresistance

There is strong evidence that radioresistance can be genetically determined and inherited, at least in some organisms. Heinrich Nöthel, a geneticist from the Freie Universität Berlincarried out the most extensive study about radioresistance mutationsusing the common fruit fly, Drosophila melanogaster, in a series of 14 publications.

Radioresistance in radiation oncology

Radioresistance is also a term sometimes used in medicine (oncology) for cancercells which are difficult to treat with radiotherapy. Radioresistance of cancer cells may be intrinsic or induced by the radiation therapy itself.

See also

• Radiosensitivity
• Deinococcus radiodurans (the most radioresistant organism, an extremophilicbacterium)

References

• Joiner, M.C. Induced Radioresistance: An Overview and Historical Perspective. Int J Rad Biol, 65(1): 79-84, 1994 (Abstract)
• Ling CC, Endlich B. Radioresistance induced by oncogenic transformation. Radiat Res. 1989 Nov;120(2):267-79. PMID 2694214
• Cordeiro AR, Marques EK, Veiga-Neto AJ. Radioresistance of a natural population of Drosophila willistoni living in a radioactive environment. Mutat Res. 1973 Sep;19(3):325-9. PMID 4796403
• Nöthel H. Adaptation of Drosophila melanogaster populations to high mutation pressure: evolutionary adjustment of mutation rates. Proc Natl Acad Sci U S A. 1987 Feb;84(4):1045-9. PMID 3103121

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It uses material from the http://en.wikipedia.org/wiki/Radioresistance Wikipedia article Radioresistance.