Mutagen
[1] In 1567, Swiss physician Paracelsus suggested that an unidentified substance in mined ore (identified as radon gas in modern times) caused a wasting disease in miners,[2] and in England, in 1761, John Hill made the first direct link of cancer to chemical substances by noting that excessive use of snuff may cause nasal cancer.
[4] In 1915, Yamagawa and Ichikawa showed that repeated application of coal tar to rabbit's ears produced malignant cancer.
[5] Subsequently, in the 1930s the carcinogen component in coal tar was identified as a polyaromatic hydrocarbon (PAH), benzo[a]pyrene.
[2][6] Polyaromatic hydrocarbons are also present in soot, which was suggested to be a causative agent of cancer over 150 years earlier.
The association of exposure to radiation and cancer had been observed as early as 1902, six years after the discovery of X-ray by Wilhelm Röntgen and radioactivity by Henri Becquerel.
[8][9] The mutagenic property of mutagens was first demonstrated in 1927, when Hermann Muller discovered that x-rays can cause genetic mutations in fruit flies, producing phenotypic mutants as well as observable changes to the chromosomes,[10][11] visible due to the presence of enlarged "polytene" chromosomes in fruit fly salivary glands.
[14] He also found that X-rays not only mutate genes in fruit flies,[10] but also have effects on the genetic makeup of humans.
[15][better source needed] Similar work by Lewis Stadler also showed the mutational effect of X-rays on barley in 1928,[16] and ultraviolet (UV) radiation on maize in 1936.
[17] The effect of sunlight had previously been noted in the nineteenth century where rural outdoor workers and sailors were found to be more prone to skin cancer.
[26] Meanwhile, compounds which are not directly mutagenic but stimulate cell growth which can reduce the effectiveness of DNA repair and indirectly increase the chance of mutations, and therefore that of cancer.
Also a DNA double-strand break may be repaired by an inaccurate process leading to an altered base pair, a mutation.
Similar results are also obtained in studies with radiations, indicating that there may be no safe threshold for mutagens.
More recent approaches with sensitive analytical methods have shown that there may be non-linear or bilinear dose-responses for genotoxic effects, and that the activation of DNA repair pathways can prevent the occurrence of mutation arising from a low dose of mutagen.
[47] Antioxidants are an important group of anticarcinogenic compounds that may help remove ROS or potentially harmful chemicals.
Selenium, which is present as a micronutrient in vegetables, is a component of important antioxidant enzymes such as gluthathione peroxidase.
Many phytonutrients may counter the effect of mutagens; for example, sulforaphane in vegetables such as broccoli has been shown to be protective against prostate cancer.
[54] An effective precautionary measure an individual can undertake to protect themselves is by limiting exposure to mutagens such as UV radiations and tobacco smoke.
[50] Overly-browned starchy food such as bread, biscuits and potatoes can generate acrylamide, a chemical shown to cause cancer in animal studies.
[62] For certain mutagens, such as dangerous chemicals and radioactive materials, as well as infectious agents known to cause cancer, government legislations and regulatory bodies are necessary for their control.
These systems check for large scale changes to the chromosomes and may be used with cell culture or in animal test.
The chemicals under test are usually administered in the food and in the drinking water, but sometimes by dermal application, by gavage, or by inhalation, and carried out over the major part of the life span for rodents.
Animals are first treated with suspected mutagen, the mouse DNA is then isolated and the phage segment recovered and used to infect E. coli.
Using similar method as the blue-white screen, the plaque formed with DNA containing mutation are white, while those without are blue.
In science fiction, mutagens are often represented as substances that are capable of completely changing the form of the recipient or granting them superpowers.
Mutagens are also featured in video games such as Cyberia, System Shock, The Witcher, Metroid Prime: Trilogy, Resistance: Fall of Man, Resident Evil, Infamous, Freedom Force, Command & Conquer, Gears of War 3, StarCraft, BioShock, Fallout, Underrail, and Maneater.
