Radioresistance
For example, the study of environment, animals and plants around the Chernobyl disaster area has revealed an unexpected survival of many species, despite the high radiation levels.
A Brazilian study in a hill in the state of Minas Gerais which has high natural radiation levels from uranium deposits, has also shown many radioresistant insects, worms and plants.
[2][3] Certain extremophiles, such as the bacteria Deinococcus radiodurans and the tardigrades, can withstand large doses of ionizing radiation on the order of 5,000 Gy.
Several studies have documented this effect in yeast, bacteria, protozoa, algae, plants, insects, as well as in in vitro mammalian and human cells and in animal models.
Several cellular radioprotection mechanisms may be involved, such as alterations in the levels of some cytoplasmic and nuclear proteins and increased gene expression, DNA repair and other processes.
The most likely explanation[citation needed] is that his dose was fractionated into many smaller doses which were absorbed over a length of time while his wife stayed in the house more and was subjected to continuous irradiation without a break so giving the self repair mechanisms in her body less time to repair some of the damage done by the radiation.
Heinrich Nöthel, a geneticist from the Freie Universität Berlin carried out the most extensive study about radioresistance mutations using the common fruit fly, Drosophila melanogaster, in a series of 14 publications.
From the perspective of evolutionary history and causation, radioresistance does not appear to be an adaptive trait because there is no documented naturally occurring selection pressure that could have bestowed a fitness advantage to the ability for organisms to withstand doses of ionizing radiation in the range that several extremophile species have been observed to be capable of surviving.
[13] The extraordinarily efficient cellular repair mechanisms that Deinococcus species like D. radiodurans have evolved to repair heat-damage are likely also capable of reversing the effects of DNA damage wrought by ionizing radiation, such as by piecing back together any components of their genome that have been fragmented by the radiation.
The second is recruitment of highly sophisticated DNA repair mechanisms that enable the reconstruction of a fully functional genome.
The comparison in the table below is only meant to give approximate indications of radioresistance for different species and should be taken with great caution.
