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Background : Certain plants have been genetically engineered to have sense-antisense gene of a parasitic nematode. The dsRNA produced by the plant then inactivates the mRNA produced in the nematode, who, then isn't able to synthesize the corresponding protein and dies as a result.

Question : How is the dsRNA from the plant transfered to the nematode's cell ? By transformation ?

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    $\begingroup$ Apparently it is transferred by simply feeding. C.elegans feeding on E.coli producing dsRNA can produce the siRNA. C.elegans seems to have a lot of RNA transporters such as SID1. $\endgroup$ – WYSIWYG Jul 17 '15 at 9:00
  • $\begingroup$ Yes, in vitro you can simply soak the worms in a solution that contains the dsRNA (i.e. in a large-scale microtiter dish for HTP screening)--this is not the same as ingestion because the worms won't eat if there are not small particles in the liquid. For the bacteria the E. coli express the RNA hairpin in response to an inducer (IPTG) and then after ingestion the cell contents are released after the cells pass through the pharyngeal grinder, and the RNA is taken up by the gut cells, and then transferred to other cells by the transporters. $\endgroup$ – mdperry Jul 17 '15 at 10:26
  • $\begingroup$ @wysiwyg thanks. Pls see my comments on Ilan's answer. $\endgroup$ – biogirl Jul 20 '15 at 8:23
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The question is little bit unclear: is in vitro or in vivo introduction in question?

In vivo:

As the nematode feeds on the plant during its parasitic phase, it consequently assures the introduction of dsRNA and/or siRNA molecules into the nematode’s digestive system.

in vitro introduction etc ->

The status of RNAi-based transgenic research in plant nematology

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  • $\begingroup$ Why does it feed on it ? Even if it does, won't the RNAases in its digestive system break down the RNA ? $\endgroup$ – biogirl Jul 20 '15 at 8:22
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    $\begingroup$ @biogirl They feed on the plants for nutrition. RNAses should break down the RNA but I couldn't find much information about exoribonucleases in nematode digestive system. Apparently the RNA transporters are far more active. Perhaps an evolutionary adaptation. $\endgroup$ – WYSIWYG Jul 20 '15 at 8:58
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    $\begingroup$ @biogirl it is a part of a parasitic evolution. The mechanism of dsRNA introduction includes enzymatic interactions: dsRNA is introduced into the nematode digestive system by feeding on dsRNA-expressing E.coli. The dsRNA spreads to neighborhood (the SID-2 and SID-1 proteins actions), followed by cleavage of dsRNA by the RNaseIII, Dicer, in the cytoplasm. Attachment of siRNAs to the RNA-induced silencing complex (RISC) separates the strands of siRNAs and incorporates the siRNAs into the active RISC. These siRNAs target mRNA molecule and the RISC cleaves them and a gene is silenced. $\endgroup$ – Ilan Jul 20 '15 at 9:03
  • $\begingroup$ @wysiwyg Thanks ! How are active RNA transporters evolutionarily advantageous ? $\endgroup$ – biogirl Jul 21 '15 at 12:22
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    $\begingroup$ @biogirl That I cannot comment about. It could have been advantageous for some reason. There is too much to speculate here $\endgroup$ – WYSIWYG Jul 21 '15 at 13:15

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