Functional screening assays

N. Humbert, A. Zocchi, T. R. Ward, Electrophoretic behavior of streptavidin complexed to a biotinylated probe a functional screening assay for biotin-binding proteins. Electrophoresis, 2005, 26, 47-52. 

Iversen (1991) stresses the need for some in vivo testing for neurotoxicity and emphasizes the value of sensitive behavioral tests. Behavioral tests are described for mice and rats, which provide measures of mood, posture, CNS excitation, motor coordination, sedation, exploration, responsiveness, learning, and memory function. Such assays can function as primary screens for neurotoxicity before adopting a stepwise scheme of in vitro tests to discover more about the initial site of action of neurotoxic compounds. It is argued that the requirement for animal testing can be drastically reduced by adopting structured in vitro protocols such as these. 

More recently, the National Institute of Environmental Health Sciences and the National Institute for Occupational Safety and Health convened a workshop in which experts in the field of developmental immunotoxicology developed a tiered approach for assaying the developmental immunotoxicity of chemicals.18 The recommended assays were separated into three groups (1) an initial set of screening assays, (2) assays for validation of a correlation between the assay end point and functional outcomes in humans, and (3) assays for research development.18 The initial screening assays included analysis of the primary antibody response to a T-dependent antigen, the delayed type... 

However, if the gene has been cloned, but the required activity is not produced, then the functional test will fail to pick up the target gene. In this case, if some gene sequence information is available, then it may be possible to test for the presence of DNA with the expected sequence by hybridization with radio-labelled probe DNA or, more usually, by PCR. This sequence-based screening test could pick up positives which have been missed in the initial screen because the gene has been successfully cloned but the enzyme has not been produced in an active form (perhaps because expression has not occurred or because E. coli is a poor host to support production of active enzyme), or where there is no convenient function-based assay available. 

Early stages of drug discovery continue to move further and further away from biofunctional screening assays such as bacterial broths, cell cultures, and animal models, and closer towards functional assays where specific (and targeted) inter-... 

In summary, our data provide evidence for the suitability of zebrafish eleuther-oembryos as a predictive vertebrate model for evaluating the effect of individual chemicals and mixtures on thyroid gland function. TIQDT performed on zebrafish eleutheroembryos is an alternative whole-organism screening assay that provides relevant information for environmental and human risk assessments. 

WesseUs RJ, Bodmer R. (2004) Screening assays for heart function mutants in Drosophila. Biotechniques 37, 58-60, 62, 64 passim. 

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