Transient expression of DNA and RNA in parasitic helminths by using particle bombardment

Parasitic helminths (worms belonging to several metazoan phyla) cause consi derable morbidity and mortality in humans. They are an important veterinary problem, and they result in significant economic losses in animal grazing and agriculture. Experimental studies on parasitic helminths have been limi ted by a lack of parasite cell lines and methods for molecular genetic anal yses. We evaluated particle bombardment (biolistics) as a strategy to intro duce and express nucleic acids in these multicellular parasites. By using e mbryos of the parasitic nematode Ascaris as a model, we developed methods t o introduce and express both DNA and RNA during several stages of Ascaris e mbryogenesis, Biolistic transfection will facilitate experimental strategie s in Ascaris embryos complementing other biochemical tools available (e.g., in vitro whole-cell embryo extracts for transcription, RNA processing, and translation), Transfection experiments with adult schistosomes further sug gest that the biolistic strategy should be applicable to a variety of other parasitic helminths, The development of these methods provides molecular g enetic tools to study gene expression and the biology of a variety of types and developmental stages of important helminth parasites.