The citric acid cycle—also known as the Krebs cycle, Szent-Györgyi-Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of biochemical reactions to release the energy stored in nutrients through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The chemical energy released is available under the form of ATP. The Krebs cycle is used by organisms that respire (as opposed to organisms that ferment) to generate energy, either by anaerobic respiration or aerobic respiration. In addition, the cycle provides precursors of certain amino acids, as well as the reducing agent NADH, that are used in numerous other reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism. Even though it is branded as a 'cycle', it is not necessary for metabolites to follow only one specific route; at least three alternative segments of the citric acid cycle have been recognized.
An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. Many of the enzymes in the electron transport chain are embedded within the membrane.
In vitro toxicity testing is the scientific analysis of the toxic effects of chemical substances on cultured bacteria or mammalian cells. In vitro testing methods are employed primarily to identify potentially hazardous chemicals and/or to confirm the lack of certain toxic properties in the early stages of the development of potentially useful new substances such as therapeutic drugs, agricultural chemicals and food additives.
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of venom, e.g. from the puff adder or brown recluse spider are toxic to cells.
Ethidium bromide is an intercalating agent commonly used as a fluorescent tag in molecular biology laboratories for techniques such as agarose gel electrophoresis. It is commonly abbreviated as EtBr, which is also an abbreviation for bromoethane. To avoid confusion, some laboratories have used the abbreviation EthBr for this salt. When exposed to ultraviolet light, it will fluoresce with an orange colour, intensifying almost 20-fold after binding to DNA. Under the name homidium, it has been commonly used since the 1950s in veterinary medicine to treat trypanosomiasis in cattle. The high incidence of antimicrobial resistance makes this treatment impractical in some areas, where the related isometamidium chloride is used instead. Despite its reputation as a mutagen, tests have shown it to have low mutagenicity without metabolic activation.
Hypochlorous acid is an inorganic compound with the chemical formula ClOH, also written as HClO, HOCl, or ClHO. Its structure is H−O−Cl. It is an acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite anion, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine solutions. HClO cannot be isolated from these solutions due to rapid equilibration with its precursor, chlorine.
Fenobucarb is a carbamate insecticide, also widely known as BPMC. A pale yellow or pale red liquid, insoluble in water; used as an agricultural insecticide, especially for control of Hemipteran pests, on rice and cotton and moderately toxic for humans.
Fumaric acid is an organic compound with the formula HO2CCH=CHCO2H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297. The salts and esters are known as fumarates. Fumarate can also refer to the C
4H
2O2−
4 ion (in solution). Fumaric acid is the trans isomer of butenedioic acid, while maleic acid is the cis isomer.
The MTT assay is a colorimetric assay for assessing cell metabolic activity. NAD(P)H-dependent cellular oxidoreductase enzymes may, under defined conditions, reflect the number of viable cells present. These enzymes are capable of reducing the tetrazolium dye MTT, which is chemically 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, to its insoluble formazan, which has a purple color. Other closely related tetrazolium dyes including XTT, MTS and the WSTs, are used in conjunction with the intermediate electron acceptor, 1-methoxy phenazine methosulfate (PMS). With WST-1, which is cell-impermeable, reduction occurs outside the cell via plasma membrane electron transport. However, this traditionally assumed explanation is currently contended as proof has also been found of MTT reduction to formazan in lipidic cellular structures without apparent involvement of oxidoreductases.
Glutamate dehydrogenase is an enzyme observed in both prokaryotes and eukaryotic mitochondria. The aforementioned reaction also yields ammonia, which in eukaryotes is canonically processed as a substrate in the urea cycle. Typically, the α-ketoglutarate to glutamate reaction does not occur in mammals, as glutamate dehydrogenase equilibrium favours the production of ammonia and α-ketoglutarate. Glutamate dehydrogenase also has a very low affinity for ammonia, and therefore toxic levels of ammonia would have to be present in the body for the reverse reaction to proceed. However, in brain, the NAD+/NADH ratio in brain mitochondria encourages oxidative deamination. In bacteria, the ammonia is assimilated to amino acids via glutamate and aminotransferases. In plants, the enzyme can work in either direction depending on environment and stress. Transgenic plants expressing microbial GLDHs are improved in tolerance to herbicide, water deficit, and pathogen infections. They are more nutritionally valuable.
Succinate dehydrogenase complex subunit C, also known as succinate dehydrogenase cytochrome b560 subunit, mitochondrial, is a protein that in humans is encoded by the SDHC gene. This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with pheochromocytomas and paragangliomas. Alternatively spliced transcript variants have been described.
Nitro blue tetrazolium is a chemical compound composed of two tetrazole moieties. It is used in immunology for sensitive detection of alkaline phosphatase. NBT serves as the oxidant and BCIP is the AP-substrate.
Seed testing is performed for a number of reasons, including research purposes or to determine if seed storage techniques are functioning. There are four tests most commonly done. The first two listed below are common for scientific research.
Neutral red is a eurhodin dye used for staining in histology. It stains lysosomes red. It is used as a general stain in histology, as a counterstain in combination with other dyes, and for many staining methods. Together with Janus Green B, it is used to stain embryonal tissues and supravital staining of blood. Can be used for staining Golgi apparatus in cells and Nissl granules in neurons.
Succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial (SDHB) also known as iron-sulfur subunit of complex II (Ip) is a protein that in humans is encoded by the SDHB gene.
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act. The list can be found as an appendix to 40 CFR 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121.
Triphenyl tetrazolium chloride, TTC, or simply tetrazolium chloride is a redox indicator commonly used in biochemical experiments especially to indicate cellular respiration. It is a white crystalline powder, soluble in water, ethanol and acetone but insoluble in ether.
The formazans are compounds of the general formula [R-N=N-C(R')=N-NH-R"], formally derivatives of formazan [H2NN=CHN=NH], unknown in free form.
Resazurin is a phenoxazine dye that is weakly fluorescent, nontoxic, cell-permeable, and redox‐sensitive. Resazurin has a blue to purple color above pH 6.5 and an orange color below pH 3.8. It is used in microbiological, cellular, and enzymatic assays because it can be irreversibly reduced to the pink-colored and highly fluorescent resorufin (7-Hydroxy-3H-phenoxazin-3-one). At circum-neutral pH, resorufin can be detected by visual observation of its pink color or by fluorimetry, with an excitation maximum at 530-570 nm and an emission maximum at 580-590 nm.
Triazofos is a chemical compound used in acaricides, insecticides, and nematicides.
