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47-495: A FLAG-tag can be used in many different assays that require recognition by an antibody . If there is no antibody against a given protein, adding a FLAG-tag to a protein allows the protein to be studied with an antibody against the FLAG-tag sequence. Examples are cellular localization studies by immunofluorescence , immunoprecipitation or detection by SDS PAGE protein electrophoresis and Western blotting . The peptide sequence of

94-442: A microwave oven for 2–3 minutes before grilling shortens the time on the hot pan, and removes heterocyclic amine (HCA) precursors, which can help minimize the formation of these carcinogens. Frying, grilling or broiling food at high temperatures, especially starchy foods, until a toasted crust is formed generates acrylamides . This discovery in 2002 led to international health concerns. Subsequent research has however found that it

141-447: A bioassay is the "canary in the coal mine" experiment. To provide advance warning of dangerous levels of methane in the air, miners would take methane-sensitive canaries into coal mines. If the canary died due to a build-up of methane, the miners would leave the area as quickly as possible. Many early examples of bioassays used animals to test the carcinogenicity of chemicals. In 1915, Yamaigiwa Katsusaburo and Koichi Ichikawa tested

188-485: A cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells . The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division . The specific mechanisms for carcinogenic activity

235-466: A few. CERCLA identifies all radionuclides as carcinogens, although the nature of the emitted radiation ( alpha , beta , gamma , or neutron and the radioactive strength), its consequent capacity to cause ionization in tissues, and the magnitude of radiation exposure, determine the potential hazard. Carcinogenicity of radiation depends on the type of radiation, type of exposure, and penetration. For example, alpha radiation has low penetration and

282-482: A high incidence of colon cancer. Dietary increases in total fat or saturated fat result in elevated DCA and LCA in feces and elevated exposure of the colon epithelium to these bile acids. When the bile acid DCA was added to the standard diet of wild-type mice invasive colon cancer was induced in 56% of the mice after 8 to 10 months. Overall, the available evidence indicates that DCA and LCA are centrally important DNA-damaging carcinogens in colon cancer. Stomach cancer

329-488: A major source of carcinogens with an estimated 666,000 annual fatalities worldwide attributable to work related cancers. According to NIOSH , 3-6% of cancers worldwide are due to occupational exposures. Well established occupational carcinogens include vinyl chloride and hemangiosarcoma of the liver, benzene and leukemia , aniline dyes and bladder cancer , asbestos and mesothelioma , polycyclic aromatic hydrocarbons and scrotal cancer among chimney sweeps to name

376-614: A wider assessment of the occupational hazards of chemicals. The European Union classification of carcinogens is contained in the Regulation (EC) No 1272/2008. It consists of three categories: The former European Union classification of carcinogens was contained in the Dangerous Substances Directive and the Dangerous Preparations Directive . It also consisted of three categories: This assessment scheme

423-605: Is carcinogenic, if received in sufficient doses. For most people, ultraviolet radiations from sunlight is the most common cause of skin cancer. In Australia, where people with pale skin are often exposed to strong sunlight, melanoma is the most common cancer diagnosed in people aged 15–44 years. Substances or foods irradiated with electrons or electromagnetic radiation (such as microwave, X-ray or gamma) are not carcinogenic. In contrast, non-electromagnetic neutron radiation produced inside nuclear reactors can produce secondary radiation through nuclear transmutation . Alcohol

470-412: Is a United Nations initiative to attempt to harmonize the different systems of assessing chemical risk which currently exist (as of March 2009) around the world. It classifies carcinogens into two categories, of which the first may be divided again into subcategories if so desired by the competent regulatory authority: The National Toxicology Program of the U.S. Department of Health and Human Services

517-417: Is a biochemical test to estimate the potency of a sample compound. Usually this potency can only be measured relative to a standard compound. A typical bioassay involves a stimulus (ex. drugs) applied to a subject (ex. animals, tissues, plants). The corresponding response (ex. death) of the subject is thereby triggered and measured. The first use of a bioassay dates back to the late 19th century, when

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564-739: Is a carcinogen of the head and neck, esophagus, liver, colon and rectum, and breast. It has a synergistic effect with tobacco smoke in the development of head and neck cancers. In the United States approximately 6% of cancers and 4% of cancer deaths are attributable to alcohol use. Chemicals used in processed and cured meat such as some brands of bacon, sausages and ham may produce carcinogens. For example, nitrites used as food preservatives in cured meat such as bacon have also been noted as being carcinogenic with demographic links, but not causation, to colon cancer. Cooking food at high temperatures, for example grilling or barbecuing meats, may also lead to

611-761: Is a complex mixture of more than 5,300 identified chemicals. The most important carcinogens in tobacco smoke have been determined by a "Margin of Exposure" approach. Using this approach, the most important tumorigenic compounds in tobacco smoke were, in order of importance, acrolein , formaldehyde , acrylonitrile , 1,3-butadiene, cadmium, acetaldehyde, ethylene oxide, and isoprene. Most of these compounds cause DNA damage by forming DNA adducts or by inducing other alterations in DNA. DNA damages are subject to error-prone DNA repair or can cause replication errors. Such errors in repair or replication can result in mutations in tumor suppressor genes or oncogenes leading to cancer. Breast cancer

658-679: Is an intergovernmental agency established in 1965, which forms part of the World Health Organization of the United Nations . It is based in Lyon , France . Since 1971 it has published a series of Monographs on the Evaluation of Carcinogenic Risks to Humans that have been highly influential in the classification of possible carcinogens. The Globally Harmonized System of Classification and Labelling of Chemicals (GHS)

705-446: Is applied and how the response is recorded. One classical bioassay is the Ames test . A strain of Salmonella that requires histidine to grow is put on two plates with growth medium containing minimal amounts of histidine and some rat liver extract (to mimick liver metabolism). A suspected mutagen is added to one plate. If the plate with the suspected mutagen grows more visible colonies, it

752-664: Is being phased out in favor of the GHS scheme (see above), to which it is very close in category definitions. Under a previous name, the NOHSC, in 1999 Safe Work Australia published the Approved Criteria for Classifying Hazardous Substances [NOHSC:1008(1999)]. Section 4.76 of this document outlines the criteria for classifying carcinogens as approved by the Australian government. This classification consists of three categories: In this section,

799-738: Is known to cause stomach cancer and MALT lymphoma . Hepatitis B and C are associated with the development of hepatocellular cancer. HPV is the primary cause of cervical cancer . Tobacco smoke contains at least 70 known carcinogens and is implicated in the development of numerous types of cancers including cancers of the lung, larynx, esophagus, stomach, kidney, pancreas, liver, bladder, cervix, colon, rectum and blood. Potent carcinogens found in cigarette smoke include polycyclic aromatic hydrocarbons (PAH, such as benzo(a)pyrene), benzene , and nitrosamine . Given that populations of workers are more likely to have consistent, often high level exposures to chemicals rarely encountered in normal life, much of

846-446: Is mandated to produce a biennial Report on Carcinogens . As of August 2024, the latest edition was the 15th report (2021). It classifies carcinogens into two groups: The American Conference of Governmental Industrial Hygienists (ACGIH) is a private organization best known for its publication of threshold limit values (TLVs) for occupational exposure and monographs on workplace chemical hazards. It assesses carcinogenicity as part of

893-651: Is not a hazard outside the body, but emitters are carcinogenic when inhaled or ingested. For example, Thorotrast , a (incidentally radioactive) suspension previously used as a contrast medium in x-ray diagnostics, is a potent human carcinogen known because of its retention within various organs and persistent emission of alpha particles. Low-level ionizing radiation may induce irreparable DNA damage (leading to replicational and transcriptional errors needed for neoplasia or may trigger viral interactions) leading to pre-mature aging and cancer . Not all types of electromagnetic radiation are carcinogenic. Low-energy waves on

940-429: Is not likely that the acrylamides in burnt or well-cooked food cause cancer in humans; Cancer Research UK categorizes the idea that burnt food causes cancer as a "myth". Several biologic agents are known carcinogens. Aflatoxin B 1 , a toxin produced by the fungus Aspergillus flavus which is a common contaminant of stored grains and nuts is a known cause of hepatocellular cancer . The bacteria H. Pylori

987-419: Is probably mutagenic: a mutagen might cause the strain of bacterium to regain the ability to make its own histidine. Most other forms of toxicology testing are also bioassays. Animals or cell cultures may be put under a number of levels of a suspected toxin to ascertain whether the substance causes harmful changes and at what level it does so. The LD 50 value, a common measure of acute toxicity, describes

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1034-426: Is the fourth most common cancer [990,000 cases (7.8%), 738,000 deaths (9.7%)]. Helicobacter pylori infection is the main causative factor in stomach cancer. Chronic gastritis (inflammation) caused by H. pylori is often long-standing if not treated. Infection of gastric epithelial cells with H. pylori results in increased production of reactive oxygen species (ROS). ROS cause oxidative DNA damage including

1081-649: Is the most common cancer in the world, both in terms of cases (1.6 million cases; 12.7% of total cancer cases) and deaths (1.4 million deaths; 18.2% of total cancer deaths). Lung cancer is largely caused by tobacco smoke. Risk estimates for lung cancer in the United States indicate that tobacco smoke is responsible for 90% of lung cancers. Other factors are implicated in lung cancer, and these factors can interact synergistically with smoking so that total attributable risk adds up to more than 100%. These factors include occupational exposure to carcinogens (about 9-15%), radon (10%) and outdoor air pollution (1-2%). Tobacco smoke

1128-406: Is the second most common cancer [(1.4 million cases, 10.9%), but ranks 5th as cause of death (458,000, 6.1%)]. Increased risk of breast cancer is associated with persistently elevated blood levels of estrogen . Estrogen appears to contribute to breast carcinogenesis by three processes; (1) the metabolism of estrogen to genotoxic, mutagenic carcinogens, (2) the stimulation of tissue growth, and (3)

1175-834: Is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage directly with DNA. Activation-dependent agents are relatively inert in their original form, but are bioactivated in the body into metabolites or intermediaries capable of damaging human DNA. These are also known as "indirect-acting" carcinogens. Examples of activation-dependent carcinogens include polycyclic aromatic hydrocarbons (PAHs), heterocyclic aromatic amines , and mycotoxins . Activation-independent carcinogens, or "direct-acting" carcinogens, are those that are capable of directly damaging DNA without any modification to their molecular structure. These agents typically include electrophilic groups that react readily with

1222-522: The electromagnetic spectrum including radio waves , microwaves , infrared radiation and visible light are thought not to be, because they have insufficient energy to break chemical bonds. Evidence for carcinogenic effects of non-ionizing radiation is generally inconclusive , though there are some documented cases of radar technicians with prolonged high exposure experiencing significantly higher cancer incidence. Higher-energy radiation, including ultraviolet radiation (present in sunlight ) generally

1269-565: The epitope only when FLAG-tag is present at the N-terminus. However, other available antibodies (e.g., M2) are position-insensitive. The tyrosine residue in the FLAG-tag can be sulfated when expressed on certain secreted proteins, which can affect antibody recognition of the FLAG epitope. The FLAG-tag can be used in conjunction with other affinity tags, for example a polyhistidine tag ( His-tag ), HA-tag or myc-tag . The first use of epitope tagging

1316-512: The FLAG-tag from the N-terminus to the C-terminus is: DYKDDDDK (1012 Da). Additionally, FLAG-tags may be used in tandem, commonly the 3xFLAG peptide: DYKDHD-G-DYKDHD-I-DYKDDDDK (with the final tag encoding an enterokinase cleavage site). FLAG-tag can be fused to the C-terminus or the N-terminus of a protein, or inserted within a protein. Some commercially available antibodies (e.g., M1/4E11) recognize

1363-399: The United States require some industrial dischargers and municipal sewage treatment plants to conduct bioassays. These procedures, called whole effluent toxicity tests, include acute toxicity tests as well as chronic test methods. The methods involve exposing living aquatic organisms to samples of wastewater for a specific length of time. Another example is the bioassay ECOTOX, which uses

1410-729: The bile acids deoxycholic acid (DCA) or lithocholic acid (LCA) induce production of DNA-damaging reactive oxygen species or reactive nitrogen species in human or animal colon cells. Furthermore, 14 studies showed that DCA and LCA induce DNA damage in colon cells. Also 27 studies reported that bile acids cause programmed cell death ( apoptosis ). Increased apoptosis can result in selective survival of cells that are resistant to induction of apoptosis. Colon cells with reduced ability to undergo apoptosis in response to DNA damage would tend to accumulate mutations, and such cells may give rise to colon cancer. Epidemiologic studies have found that fecal bile acid concentrations are increased in populations with

1457-402: The carcinogenicity of coal tar using the inner surface of rabbit's ears. From the 1940s to the 1960s, animal bioassays were primarily used to test the toxicity and safety of drugs, food additives, and pesticides. Beginning in the late 1960s and 1970s, reliance on bioassays increased as public concern for occupational and environmental hazards increased. Bioassay can be classified by how it

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1504-720: The carcinogenicity of substances include the National Toxicology Program of the US Public Health Service , NIOSH , the American Conference of Governmental Industrial Hygienists and others. There are numerous sources of exposures to carcinogens including ultraviolet radiation from the sun, radon gas emitted in residential basements, environmental contaminants such as chlordecone , cigarette smoke and ingestion of some types of foods such as alcohol and processed meats . Occupational exposures represent

1551-422: The carcinogens implicated as the main causative agents of the four most common cancers worldwide are briefly described. These four cancers are lung, breast, colon, and stomach cancers. Together they account for about 41% of worldwide cancer incidence and 42% of cancer deaths (for more detailed information on the carcinogens implicated in these and other cancers, see references ). Lung cancer (pulmonary carcinoma)

1598-645: The cumulative scientific evidence regarding the potential carcinogenicity of specific substances. Foremost among these is the International Agency for Research on Cancer (IARC). IARC routinely publishes monographs in which specific substances are evaluated for their potential carcinogenicity to humans and subsequently categorized into one of four groupings: Group 1: Carcinogenic to humans, Group 2A: Probably carcinogenic to humans, Group 2B: Possibly carcinogenic to humans and Group 3: Not classifiable as to its carcinogenicity to humans. Other organizations that evaluate

1645-701: The dose at which a substance is lethal to 50% of tested animals. The potency of a drug may be measured using a bioassay. Environmental bioassays are generally a broad-range survey of toxicity . A toxicity identification evaluation is conducted to determine what the relevant toxicants are. Although bioassays are beneficial in determining the biological activity within an organism, they can often be time-consuming and laborious. Organism-specific factors may result in data that are not applicable to others in that species. For these reasons, other biological techniques are often employed, including radioimmunoassays . See bioindicator . Water pollution control requirements in

1692-514: The epitope was characterized and used as a tag, the FLAG epitope was an idealized, artificial design, to which monoclonal antibodies were raised. The FLAG-tag's sequence was optimized for compatibility with proteins it is attached to, in that FLAG-tag is more hydrophilic than other common epitope tags and therefore less likely to reduce the activity of proteins to which FLAG-tag is appended. In addition, N-terminal FLAG tags can be removed readily from proteins once they have been isolated, by treatment with

1739-737: The evidence for the carcinogenicity of specific agents is derived from studies of workers. Selected carcinogens Not in widespread use, but found in: circadian disruption Carcinogens can be classified as genotoxic or nongenotoxic. Genotoxins cause irreversible genetic damage or mutations by binding to DNA . Genotoxins include chemical agents like N-nitroso-N-methylurea (NMU) or non-chemical agents such as ultraviolet light and ionizing radiation . Certain viruses can also act as carcinogens by interacting with DNA. Nongenotoxins do not directly affect DNA but act in other ways to promote growth. These include hormones and some organic compounds. The International Agency for Research on Cancer (IARC)

1786-438: The formation of minute quantities of many potent carcinogens that are comparable to those found in cigarette smoke (i.e., benzo[ a ]pyrene ). Charring of food looks like coking and tobacco pyrolysis , and produces carcinogens. There are several carcinogenic pyrolysis products, such as polynuclear aromatic hydrocarbons, which are converted by human enzymes into epoxides , which attach permanently to DNA. Pre-cooking meats in

1833-425: The foundation of bioassays was laid down by German physician Paul Ehrlich. He introduced the concept of standardization by the reactions of living matter. His bioassay on diphtheria antitoxin was the first bioassay to receive recognition. His use of bioassay was able to discover that administration of gradually increasing dose of diphtheria in animals stimulated production of antiserum. One well known example of

1880-553: The incidence of DNA damage and breast cancer risk. Consumption of alcohol has also been linked to an increased risk for breast cancer. Colorectal cancer is the third most common cancer [1.2 million cases (9.4%), 608,000 deaths (8.0%)]. Tobacco smoke may be responsible for up to 20% of colorectal cancers in the United States. In addition, substantial evidence implicates bile acids as an important factor in colon cancer. Twelve studies (summarized in Bernstein et al. ) indicate that

1927-418: The major base alteration 8-hydroxydeoxyguanosine (8-OHdG). 8-OHdG resulting from ROS is increased in chronic gastritis. The altered DNA base can cause errors during DNA replication that have mutagenic and carcinogenic potential. Thus H. pylori -induced ROS appear to be the major carcinogens in stomach cancer because they cause oxidative DNA damage leading to carcinogenic mutations. Diet is also thought to be

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1974-571: The measured response is binary, the assay is quantal ; if not, it is quantitative . A bioassay may be used to detect biological hazards or to give an assessment of the quality of a mixture. A bioassay is often used to monitor water quality as well as wastewater discharges and its impact on the surroundings. It is also used to assess the environmental impact and safety of new technologies and facilities. Bioassays are essential in pharmaceutical, medical and agricultural sciences for development and launching of new drugs, vitamins, etc. A bioassay

2021-575: The microalgae Euglena gracilis to test the toxicity of water samples. ( See Bioindicator#Microalgae in water quality ) Carcinogen A carcinogen ( / k ɑːr ˈ s ɪ n ə dʒ ən / ) is any agent that promotes the development of cancer . Carcinogens can include synthetic chemicals , naturally occurring substances, physical agents such as ionizing and non-ionizing radiation , and biologic agents such as viruses and bacteria . Most carcinogens act by creating mutations in DNA that disrupt

2068-569: The net negative charge of DNA molecules. Examples of activation-independent carcinogens include ultraviolet light , ionizing radiation and alkylating agents . The time from exposure to a carcinogen to the development of cancer is known as the latency period . For most solid tumors in humans the latency period is between 10 and 40 years depending on cancer type. For blood cancers, the latency period may be as short as two. Due to prolonged latency periods identification of carcinogens can be challenging. A number of organizations review and evaluate

2115-690: The repression of phase II detoxification enzymes that metabolize ROS leading to increased oxidative DNA damage. The major estrogen in humans, estradiol , can be metabolized to quinone derivatives that form adducts with DNA. These derivatives can cause depurination, the removal of bases from the phosphodiester backbone of DNA, followed by inaccurate repair or replication of the apurinic site leading to mutation and eventually cancer. This genotoxic mechanism may interact in synergy with estrogen receptor-mediated, persistent cell proliferation to ultimately cause breast cancer. Genetic background, dietary practices and environmental factors also likely contribute to

2162-509: The specific protease, enterokinase ( enteropeptidase ). The third report of epitope tagging, ( HA-tag ), appeared about one year after the Flag system had been first shipped. Bioassay A bioassay is an analytical method to determine the potency or effect of a substance by its effect on living animals or plants ( in vivo ), or on living cells or tissues ( in vitro ). A bioassay can be either quantal or quantitative, direct or indirect. If

2209-418: Was described by Munro and Pelham in 1984. The FLAG-tag was the second example of a fully functional, improved epitope tag, published in the scientific literature. and was the only epitope tag to be patented. It has since become one of the most commonly used protein tags in laboratories worldwide. Unlike some other tags (e.g. myc, HA), where a monoclonal antibody was first isolated against an existing protein, then

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