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A method for the quantitation of the effects on a biological system by its exposure to a substance, as well as the quantitation of the concentration of a substance by some observable effect on a biological system. The biological material in which the effect is measured can range from subcellular components and microorganisms to groups of animals. The substance can be stimulatory, such as an ion increasing taxis behavior in certain protozoans, or inhibitory, such as an antibiotic for bacterial growth. Bioassays are most frequently used when there is a number of steps, usually poorly understood, between the substance and the behavior observed, or when the substance is a complex mixture of materials and it is not clear what the active components are. Bioassays can be replaced, in time, by either a more direct measure of concentration of the active principle, such as an analytical method (for example, mass spectrometry, high-pressure liquid chromatography, radioimmunoassay), or a more direct measurement of the effect, such as binding to a surface receptor in the case of many drugs, as the substance or its mechanism of action is better characterized.

Assays to quantitate the effects of an exposure model the effect of a substance in the real world. Complex biological responses can be estimated by laboratory culture tests, which use, for example, bacteria or cells cultured in a petri dish (usually to model an effect either on the organism of interest, such as bacteria, or on some basic cellular function); by tissue or organ culture, which isolates pieces of tissue or whole organs in a petri dish (usually to model organ function); or in whole animals (usually to model complex organismic relationships).


(analytical chemistry)
A method for quantitatively determining the concentration of a substance by its effect on the growth of a suitable animal, plant, or microorganism under controlled conditions.
References in periodicals archive ?
Key words: Tagosodes orizicolus, Homoptera, rice delphacid, bioassay, rearing, sugar diet, Bacillus thuringiensis, [delta]-endotoxins.
In the time it takes a scientist to manually measure one bioassay plate, AutoZONE enables a laboratory to analyse 25 plates and produce extremely accurate results.
Comparison of the mouse bioassay and enzyme-linked immunosorbent assay procedures for the detection of type A botulinal toxin in food.
The brine shrimp lethality bioassay was carried out according to McLaughlin et al.
The detection limit of the bioassay, defined as the testosterone concentration that produced a luciferase activity 2 SD above the mean of 10 samples of charcoal-stripped serum (used to reduce the contaminating steroids from the serum), was 0.
Pettis based the bioassay on one that he and ARS entomologists Mark F.
No single bioassay meets all of these requirements, so a combination of different bioassays is, undoubtedly, the best approach to screening.
In a carcinogenesis bioassay, test animals are administered large doses over a lifetime, and at the end of the study, autopsies are used to find cancer evidence.
The analyzer uses lasers and high-speed digital signal processors, similar to those used in home electronics, to simultaneously identify the bioassay and measure the result.
Luminex' approach to partnering with various firms to exploit its automated bioassay hardware platform seems to be working.
2) Are the bioassay organisms ecologically relevant?
Another technique used by the ATL to detect endocrine disrupting chemicals in water is in vivo bioassay using fish.