Extraction and Purification of Nucleic Acids from Schistosomes

The preparation of nucleic acids from schistosomes can be divided into several stages, beginning with the collection and cleaning of the parasite material, its subsequent mechanical disruption to release cellular contents, the separation of nucleic acids from that lysate and, finally, the recovery and purification of DNA or RNA. Most of the techniques described have been adapted from those given in standard molecular biology texts (1 ,2 ) and, in our laboratories, give consistent results (3 –6 ). All reagents should be of “Analar” quality or better, stock solutions should be made using sterile water and either autoclaved or filtered through a sterile Millipore (or equivalent) ultrafiltration device before use, glassware, plasticware, pipet tips, and microfuge tubes should be sterile, and disposable gloves should be worn throughout and changed frequently. Extra precautions, because of the susceptibility of RNA to endogenous RNases, must be taken during RNA preparation. These will be outlined in the appropriate protocols. Once an extraction procedure has begun, it is advisable to proceed as rapidly as possible to its conclusion or the nucleic acids may degrade. As a general rule, all procedures should be performed at 0–4�C unless otherwise mentioned.