transgenesis in parasitic worm

Model Organism: Worms Scientific Discussion
1

Hi everyone,

I am a parasitologist but not working on C elegans, and I have a naive question. I would like to know why transgenesis in parasitic worms seems to be so more difficult that in C. elegans. Is it mainly a problem of absence of adequate in vitro cultivation system for these worms?

Thanks for your help

seremela

2

Hi Seremela,

This is just my humble opinion, but I think that there are at least two issues:

  1. Difficulties in culturing large amounts of animals in a controlled in vitro system. To my knowledge, the parasitic nematode with the best developed transgenesis tools is Strongyloides, which has a free-living stage. James Lok has done some really nice work using piggybac transposons to create stable transgenic lines. Transgenic Brugia can be generated by either bombardment or CaCl2 transfection. I suppose that C. elegans is much more amenable to transgenesis because we can inject DNA directly into a syncytial gonad and screen hundreds to thousands of progeny for a selectable marker (see next point).

  2. Lack of good transgenesis markers. A lot of early C. elegans markers were phenotypic (rol-6) or rescued mutations in the injection background. It seems like the fluorescent markers are the way forward with parasitic nematodes, but I think that more work is needed to know what elements to include in these GFP markers. ie. promoter choice, addition of appropriate intronic sequence and UTRs. In the case of the Strongyloides work, it looked like they found suitable promoters and 3’ UTRs for expression. .

best wishes,

Jordan