mansoni actin 1.1 gene (23) was constructed and transfected into schistosomes
by electroporation of larval stages together with mRNAs encoding the piggyBac transposase. The activity of piggyBac was determined by plasmid excision assays, and the recovery of excised plasmids from tissues of transformed schistosomules in these assays indicated that piggyBac was Selleckchem BVD-523 active in the worm. Southern blot hybridization analysis of genomic DNAs from populations of schistosomules transformed with donor constructs plus helper transposase mRNA detected numerous variable length luciferase-positive signals. These findings further indicated piggyBac transposon insertions into the schistosome chromosomes. piggyBac integration sites were detected by a PCR technique. Numerous piggyBac integrations were detected and, after cloning, the fragments sequenced
ranged in size from approximately 1·5 to 4 kb. Sequence analysis indicated that integration of piggyBac took place at numerous loci in the schistosome genome at target TTAA sites. The discovery of sequence-specific Selleckchem RXDX-106 gene silencing in response to double-stranded RNAs (dsRNA) has had an enormous impact on molecular biology by uncovering an unsuspected layer of gene regulation. The process, also known as RNA interference (RNAi) or RNA silencing, involves complementary pairing of dsRNAs with their homologous messenger RNA targets, thereby preventing their expression, and leading ultimately to their degradation, or interfering with protein translation (33). Since its discovery, RNAi technology has been used widely as a reverse genetics tool in C. elegans, Drosophila and many other organisms, including zebrafish, plants, human, mouse and mammalian cell culture. The ability to inhibit gene activity on a post-transcriptional
level allows generation Thalidomide of loss-of-function mutants to study gene function, or identification and validation of novel therapeutic targets [reviewed in ref. (34)]. In C. elegans, silencing was found to have high potency and specificity, and was activated throughout the treated animal (35,36), even in cells that did not encounter the double-stranded RNA. It has now been revealed that a complex protein machinery is involved in the transport of the silencing signal. This raises the possibility that animals can communicate gene-specific silencing information between cells (37). In schistosomes, the presence of transcripts encoding dicer and RISC-associated proteins (piwi/argonaute orthologs) was relatively recently described (6,38,39). SmDicer was later shown to contain all domains that are characteristic of metazoan dicers including an amino terminal helicase domain, DUF283, a PAZ domain, two RNAse III domains and an RNA binding domain. An examination of the available S.