Gene silencing in C. elegans
"pLT63 contains 0.8 kb of the fem-1 gene inserted into the L4440 vector" (1). The gene fem-1 is involved in determining the male sexual trait in C. elegans (you can verify this on uniprot). It may be best, however, to stick to a "normal" plasmid like L4440 that'll just have your tph-1 insert ligated in.