Plasmids can be transferred to E. coli. These transformed E. coli can be fed to C. elegans to silence its gene expression by RNAi.

How can E.coli release RNAi to C. elegans? Even if we assume E. coli could enter cells of C. elegans for being intracellular Bacteria, it is hard to imagine that RNAi will exit E.coli directly and enter C.elegan's cells? Normally, no cells or bacteria will release RNA or genomic material outside of their cells?

  • $\begingroup$ @Chris Is there a way of merging this question with this one biology.stackexchange.com/questions/38586/… ? While they are duplicate questions, this one asks the question in a clearer, more precise manner? $\endgroup$
    – AMR
    Oct 15, 2015 at 3:57
  • $\begingroup$ "Normally, no cells or bacteria will release RNA or genomic material outside of their cells?" Horizontal Gene transfer in Bacteria. Human immune system Neutrophils and Neutrophil Extracellular Traps... $\endgroup$
    – AMR
    Oct 15, 2015 at 5:18
  • $\begingroup$ This post provides some additional information on how dsRNA is taken up by C. elegans $\endgroup$
    Oct 15, 2015 at 10:26

1 Answer 1


Yes, as bizarre as it may seem, that is what happens. The E. coli express a double-stranded RNA hairpin (under the regulation of an inducible promoter), and the RNA contains a sequence derived from a C. elegans gene. When the worms eat the bacteria they grind them up in their pharynx, and release the cell contents (including the induced RNA) into the worms' gut. The gut cells are able to absorb the dsRNA and transport it to other cells as well. The RNAi pathway processes the inhibitory RNAs to down regulate the target gene.

  • $\begingroup$ Now that is surprising! +1. I tried to edit the question. Could you check if it's OK? It's not really my expertise. $\endgroup$
    – AliceD
    Oct 15, 2015 at 3:56
  • $\begingroup$ You can also add a note on RNA transporters in C.elegans (Sid1/2). Though I am not sure, I guess that C.elegans (or perhaps related organisms) expresses these transporters more than other organisms that we know. $\endgroup$
    Oct 15, 2015 at 6:05
  • $\begingroup$ @WYSIWYG Ilan amd you had given similar answer to a question of mine about c.elegans. I think my question cud be merged with this one. ( amnt able to provide the link.... using app) $\endgroup$
    – biogirl
    Oct 15, 2015 at 14:09
  • $\begingroup$ First of all, gut cells can absorb the dsRNA, but we are talking about the whole body's cells in C.elegans! If we transform RNAi of EGFP, it will silence the whole body's EGFP... or not? Second, RNAi is made by E.coli or C.elegans? I am not talking about dsRNA. If RNAi is made by C.elegans, it means C.elegans must absorb the dsRNA releasing from E.coli. As far as I know, dsRNA might be bigger than proteins... is it possible to absorb the dsRNA directly? And also, back to the first question, how can dsRNA expend to the whole body of C.elegans to silence most of cells' gene in the whole body? $\endgroup$
    – Roger L.
    Oct 15, 2015 at 14:25
  • 1
    $\begingroup$ @RogerL. You are confusing the term RNAi, which is a biological regulatory mechanism that degrades mRNA, with small dsRNA, which can trigger the RNAi pathway. The bacteria synthesize the dsRNA, and this is released when the bacteria die. The C. elegans cells absorb, or incorporate those bacterially synthesized dsRNAs AND contain transporters that spread the dsRNA between adjacent cells. So yes, EGFP expressed in bodywall muscle will be silenced by dsRNA ingested in the gut. The RNAi complex exists in all worm cells. $\endgroup$
    – mdperry
    Oct 16, 2015 at 2:18

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