CTAB (cetyltrimethylammonium bromide) DNA extraction is a method for isolating genomic DNA from different tissues. This method employs a cationic detergent to break down cell membranes and contain contamination or interference from compounds such plant secondary metabolites. We have modified the CTAB protocol to suit DNA isolation from different tissue types. We found that by adjusting the percentage of CTAB in combination with modifying subsequent washing steps, total DNA recovery is optimized and increased. For plants, this protocol has been used with different solanaceous plants such asCapsicum annuum,Nicotiana benthamiana,Nicotiana tabacum,Solanum lycopersicum, andSolanum tuberosum, whose phenolic acid content is usually an obstacle to obtaining genomic DNA free of contamination. This protocol has also been used withArabidopsis thaliana, Marchantia polymorpha,Oryza sativa, and differentCitrusandPopulusspecies. For animals, this protocol has been used with root-knot nematodes (Meloidogynespp.), cyst nematodes (GloboderaandHeteroderaspp.), aphids, mites, and thrips. This protocol has also been used with mammalian hair follicles and sperm. For fungi, this protocol has been used with mycelia of different fungal genera. This protocol allows for standardization of DNA extraction, optimization with regard to tissue type, and improved repeatability across studies.

Nematode bioassays form a useful approach to evaluate the toxicity of chemical compounds of interest. Such evaluations are important for confirming a compound's effectiveness and the duration thereof. In medicine, it is essential to know the minimally effective dose of a drug compound to supply so that overdosing may be prevented. In agriculture, nematode bioassays are crucial tools for conducting efficacy and safety assessments before any soil application of novel chemicals, thereby avoiding the build-up of hazardous waste. Nematodes are known as bioindicators of soil health status and can be very sensitive to soil modifications. Changes in soil composition and structure will affect the types and species of nematodes that inhabit a patch of soil, making them useful indicators for testing the effects of distinct compounds. Bioassays allow observation of changes in nematode behavior as well as changes in their mobility and mortality.Caenorhabditis elegans, the model nematode, has been used to observe its responses to exposure to different compounds. Other bioassays have employed plant-parasitic nematodes such as stubby root nematodes (e.g.,TrichodorusandParatrichodorusspp.) and root-knot nematodes (Meloidogynespp.). In vitroassays can be used to perform rapid analyses in the laboratory. These tests can help reveal the molecular and cellular mechanisms of a compound’s toxicity through changes in nematode behavior, mobility, and death when working with juveniles. When working with adult nematodes, effects on nematode egg hatch can also be analyzed.