The use of biotinylated DNA probes in parentage testing: non-isotopic labeling and non-toxic extraction.

With a few exceptions DNA probing techniques require the use of radioisotopes and toxic DNA extraction techniques which render the method expensive, potentially hazardous and time-consuming. Most isotopic labeling techniques use the isotope 32P and require 3-10 days to visualize bands after hybridization. An alternative approach is based on the use of non-isotopic detection methods. The available non-isotopic techniques were assessed and their practicality tested. All probes analyzed were tested on samples extracted with a non-toxic extraction procedure using 6 M NaCl as the substitute for phenol and isochloroform. By manipulating probe sizes, blocking agents, selection of membrane and detection system, it is feasible to use non-isotopic labeling and detection in routine parentage testing. Reproducible results were obtained with labeling a variety of DNA probes of various sizes, plasmid and inserts. With an absence of waste disposal costs, probes that are stable for over two years and a staining procedure which takes 3-5 h versus days the technique is well suited for a normal laboratory setting. The next key to the acceptability of DNA testing will be the commercial availability of DNA probes for widespread use.