Extreme care should be used to identify and verify positive reactions, however, because cross-reactions are common. Counterstaining is essential for examining worms by immunofluorescence and is used to identify the exact cell in which an antigen appears. Methods for counterstaining include labeling all cells with a fluorescent dye that is specific for nucleic acids (e.g., DAPI or propidium iodide) and using GFP driven by tissue-specific promoters. - [Read Antibody Addition and Detection for Staining Caenorhabditis elegans Protocol]
Coimmunoprecipitation is one of the most useful techniques for revealing protein-protein interactions. Good negative controls to verify the specificity of the coimmunoprecipitation procedure are (1) performing the same immunoprecipitation experiment using beads coupled to the preimmune serum and (2) probing the Western blot with antibodies against protein known not to interact with the coimmunoprecipitated proteins under physiological conditions. - [Read Protein Coimmunoprecipitation in Arabidopsis Protocol]
RAPD is a procedure for typing and fingerprinting isolates of a species. It can be used for epidemiological studies, such as investigations into hospital outbreaks and as a laboratory aid to keep track of cultures and to verify that mutants generated in the laboratory are genetically identical to the parental strain. In our hands, the use of one primer, R108, is sufficiently discriminatory to distinguish between the isolates of different strains. - [Read Random Amplification of Polymorphic DNA (RAPD) Typing and Fingerprinting Protocol]