This study was supported by grants from Taiwan (Ministry of Science and Technology, MOST 100-2923-B-002-002-MY3 and 106-2313-B-002-011-MY3 to H.J.L.), the Czech Republic (Grant agency of South Bohemia University, GAJU grant 065/2017/P to Y.H.L), and Spain (Spanish Ministry of Economy and Competitiveness, grants CGL2012-36251 and CGL2015-64727-P to X.B., and the Catalan Government, grant 2014 SGR 619 to X.B.); it also received financial support from the European Fund for Economic and Regional Development (FEDER funds to X.B.).

1. Synthesis and Preparation of dsRNA
<ol>
	<li>Identify the dsRNA target sites in the 3&#39; untranslated region of the target genes. The dsTub is used for targeting the &#945;-tubulin (tub) gene (GenBank accession number: KX228233), and dsEGFP as a negative dsRNA control is designed from the sequence of enhanced green fluorescence protein (EGFP; GenBank accession number: LC311024).</li>
	<li>Perform standard PCR amplification to synthesize the dsRNA templates with gene-specific primers containing the T7 promoter sequ...

<ol>
	<li>Hammond, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dicing+and+slicing:+The+core+machinery+of+the+RNA+interference+pathway.">Dicing and slicing: The core machinery of the RNA interference pathway.</a> FEBS Lett. 579, 5822-5829 (2005).</li><li>Bell&#233;s, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beyond+drosophila:+RNAi+in+vivo+and+functional+genomics+in+insects.">Beyond drosophila: RNAi in vivo and functional genomics in insects.</a> Annu. Rev. Entomol. 55, 111-128 (2010).</li><li>Wynant, N., Santos, D., Vanden Broeck, J., Jeon, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+Five+-+Biological+Mechanisms+Determining+the+Success+of+RNA+Interference+in+Insects.">Chapter Five - Biological Mechanisms Determining the Success of RNA Interference in Insects.</a> International Review of Cell and Molecular Biology. 312, 139-167 (2014).</li><li>San Miguel, K., Scott, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+next+generation+of+insecticides:+dsRNA+is+stable+as+a+foliar-applied+insecticide.">The next generation of insecticides: dsRNA is stable as a foliar-applied insecticide.</a> Pest Manag. Sci. 72, 801-809 (2016).</li><li>Scott, J. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+the+elements+of+successful+insect+RNAi.">Towards the elements of successful insect RNAi.</a> J. Insect Physiol. 59, 1212-1221 (2013).</li><li>Joga, M. R., Zotti, M. J., Smagghe, G., Christiaens, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNAi+efficiency,+systemic+properties,+and+novel+delivery+methods+for+pest+insect+control:+What+we+know+so+far.">RNAi efficiency, systemic properties, and novel delivery methods for pest insect control: What we know so far.</a> Front. Physiol. 7, (2016).</li><li>Garbutt, J. S., Bell&#233;s, X., Richards, E. H., Reynolds, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Persistence+of+double-stranded+RNA+in+insect+hemolymph+as+a+potential+determiner+of+RNA+interference+success:+Evidence+from+Manduca+sexta+and+Blattella+germanica.">Persistence of double-stranded RNA in insect hemolymph as a potential determiner of RNA interference success: Evidence from Manduca sexta and Blattella germanica.</a> J. Insect Physiol. 59, 171-178 (2013).</li><li>Arimatsu, Y., Kotani, E., Sugimura, Y., Furusawa, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+characterization+of+a+cDNA+encoding+extracellular+dsRNase+and+its+expression+in+the+silkworm,+Bombyx+mori.">Molecular characterization of a cDNA encoding extracellular dsRNase and its expression in the silkworm, Bombyx mori.</a> Insect Biochem. Mol. Biol. 37, 176-183 (2007).</li><li>Wang, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+RNAi+efficacy+among+insect+species+is+attributable+to+dsRNA+degradation+in+vivo.">Variation in RNAi efficacy among insect species is attributable to dsRNA degradation in vivo.</a> Insect Biochem. Mol. Biol. 77, 1-9 (2016).</li><li>Wynant, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification,+functional+characterization+and+phylogenetic+analysis+of+double+stranded+RNA+degrading+enzymes+present+in+the+gut+of+the+desert+locust,+Schistocerca+gregaria.">Identification, functional characterization and phylogenetic analysis of double stranded RNA degrading enzymes present in the gut of the desert locust, Schistocerca gregaria.</a> Insect Biochem. Mol. Biol. 46, 1-8 (2014).</li><li>Huang, J. -. H., Belles, X., Lee, H. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+characterization+of+hypertrehalosemic+hormone+receptor+in+relation+to+hemolymph+trehalose+and+to+oxidative+stress+in+the+cockroach+Blattella+germanica.">Functional characterization of hypertrehalosemic hormone receptor in relation to hemolymph trehalose and to oxidative stress in the cockroach Blattella germanica.</a> Exp. Endocrinol. 2, 114 (2012).</li><li>Lin, Y. -. H., Lee, C. -. M., Huang, J. -. H., Lee, H. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+regulation+of+permethrin+susceptibility+by+glutathione+S-transferase+(BgGSTD1)+in+the+German+cockroach+(Blattella+germanica).">Circadian regulation of permethrin susceptibility by glutathione S-transferase (BgGSTD1) in the German cockroach (Blattella germanica).</a> J. Insect Physiol. 65, 45-50 (2014).</li><li>Lozano, J., Kayukawa, T., Shinoda, T., Belles, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+taiman+in+insect+metamorphosis.">A role for taiman in insect metamorphosis.</a> PLOS Genet. 10, 1004769 (2014).</li><li>Lozano, J., Monta&#241;ez, R., Belles, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MiR-2+family+regulates+insect+metamorphosis+by+controlling+the+juvenile+hormone+signaling+pathway.">MiR-2 family regulates insect metamorphosis by controlling the juvenile hormone signaling pathway.</a> Proc. Natl. Acad. Sci. 112, 3740-3745 (2015).</li><li>Lin, Y. -. H., Huang, J. -. H., Liu, Y., Belles, X., Lee, H. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oral+delivery+of+dsRNA+lipoplexes+to+German+cockroach+protects+dsRNA+from+degradation+and+induces+RNAi+response.">Oral delivery of dsRNA lipoplexes to German cockroach protects dsRNA from degradation and induces RNAi response.</a> Pest Manag. Sci. 73, 960-966 (2017).</li><li>Gharavi, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chiral+cationic+polyamines+for+chiral+microcapsules+and+siRNA+delivery.">Chiral cationic polyamines for chiral microcapsules and siRNA delivery.</a> Bioorg. Med. Chem. Lett. 23, 5919-5922 (2013).</li><li>Whyard, S., Singh, A. D., Wong, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ingested+double-stranded+RNAs+can+act+as+species-specific+insecticides.">Ingested double-stranded RNAs can act as species-specific insecticides.</a> Insect Biochem. Mol. Biol. 39, 824-832 (2009).</li><li>Luo, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+responses+of+migratory+locusts+to+systemic+RNA+interference+via+double-stranded+RNA+injection+and+feeding.">Differential responses of migratory locusts to systemic RNA interference via double-stranded RNA injection and feeding.</a> Insect Mol. Biol. 22, 574-583 (2013).</li><li>Liu, J., Smagghe, G., Swevers, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+response+of+BmToll9-1+and+RNAi+machinery+genes+to+exogenous+dsRNA+in+the+midgut+of+Bombyx+mori.">Transcriptional response of BmToll9-1 and RNAi machinery genes to exogenous dsRNA in the midgut of Bombyx mori.</a> J. Insect Physiol. 59, 646-654 (2013).</li><li>Airs, P. M., Bartholomay, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+interference+for+mosquito+and+mosquito-borne+disease+control.">RNA interference for mosquito and mosquito-borne disease control.</a> Insects. 8, 4 (2017).</li><li>Taning, C. N. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oral+RNAi+to+control+Drosophila+suzukii:+Laboratory+testing+against+larval+and+adult+stages.">Oral RNAi to control Drosophila suzukii: Laboratory testing against larval and adult stages.</a> J. Pest Sci. 89, 803-814 (2016).</li><li>Wu, S. Y., McMillan, N. A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipidic+systems+for+in+vivo+siRNA+delivery.">Lipidic systems for in vivo siRNA delivery.</a> AAPS J. 11, 639-652 (2009).</li><li>Tam, Y. Y. C., Chen, S., Cullis, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+lipid+nanoparticles+for+siRNA+delivery.">Advances in lipid nanoparticles for siRNA delivery.</a> Pharmaceutics. 5, 498-507 (2013).</li><li>Xia, Y., Tian, J., Chen, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+surface+properties+on+liposomal+siRNA+delivery.">Effect of surface properties on liposomal siRNA delivery.</a> Biomaterials. 79, 56-68 (2016).</li></ol>

This protocol presents a method for effective RNAi through oral delivery of dsRNA lipoplexes, involving protection against ribonuclease digestion in the midgut juice of the German cockroach. As shown in other studies in various insect species, the poor RNAi effect through oral delivery of dsRNA is mostly accounted for by the degradation of dsRNA8,9,10. This protocol produces liposomes that serve as protective vehicles in oral de...

RNAi has been demonstrated as an effective method to knockdown gene expression through a mechanism of a post-transcriptional silencing pathway triggered by dsRNA molecules in many eukaryotes1. Over the past decade of study, RNAi has become a useful tool to study the functions of genes from development to behavior by depleting the expression of specific genes via injection and/or feeding of dsRNA in various taxa of insects2,3. Due to the specificity and robustness of the depleting effect, the application of RNAi is currently being considered as a potential strategy for pest control management4,5. However, the efficiency of RNAi varies widely between insect species, depending on the different genes being targeted and the delivery methods. A growing body of evidence suggests that the instability of dsRNA, which is degraded by ribonucleases, is a critical factor in the limited efficacy of RNAi5,6. For instance, the low RNAi sensitivity in Manduca sexta has been explained by the fact that the dsRNA mixed with hemolymph was quickly degraded within 1 hour7. Similarly, the presence of alkaline nucleases in the midgut, which efficiently degrade ingested dsRNA, is strongly correlated with low RNAi efficiency in different insect orders8,9,10.
The oral delivery of dsRNA is particularly interesting for the application of RNAi in a pest control strategy, but a method to retard the degradation of dsRNA by the nucleases in the midgut has not yet been developed, which would have the potential to ensure effective RNAi through feeding. However, the unresponsiveness of RNAi to oral delivery of dsRNA has been reported by feeding large amount of dsRNA, e.g. 50 &#181;g in Bombyx mori, or continuously feeding for 8 days (8 &#181;g dsRNA in total) in the locust species. The German cockroach, Blattella germinica, is highly sensitive to RNAi by the injection of dsRNA11,12,13,14, but is not responsive to dsRNA through feeding. Recently, Lin et al. (2017) have demonstrated that the dsRNA encapsulated with liposome carriers results in successful RNAi to knockdown the &#945;-tubulin gene expression in the midgut and trigger significant mortality of the German cockroach15. As the degradation of dsRNA in the midgut is the limiting factor for oral RNAi, the liposome carriers serve as a vehicle to protect dsRNA from degradation, which is readily applicable in other insects with strong nuclease activities in the gut. Of note, the reason for choosing the particular transfection reagent (see Table of Materials) we used as liposome carrier in the current protocol is that it has been tested for insect cell line transfection with less toxicity, according to the manufacturer&#39;s instructions. According to the comparison of different liposome transfection systems in Gharavi et al. (2013)16, the efficiency of transfecting small interfering RNA (siRNA) is approximately the same between this and other commercially available systems that have been used for dsRNA delivery systems in other insects17,18.Furthermore, our feeding method is careful enough to ensure the proper amount of dsRNA is ingested by each cockroach, and that the results are robust and confirmed. In summary, the present protocol and results demonstrate that using dsRNA lipoplexes improves dsRNA stability and opens the door to the design of the strategy oral delivery of RNAi, which is a promising approach for pest control in the future.

<table border="0" cellpadding="0" cellspacing="0" style="width:1124px;" width="1123">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">GenJe Plus DNA in vitro Transfection reagent</td>
			<td style="width:133px;">SignaGen</td>
			<td style="width:157px;">SL100499</td>
			<td style="width:481px;">for lipoplexes preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blend Taq plus</td>
			<td style="width:133px;">TOYOBO&#160;</td>
			<td style="width:157px;">BTQ-201</td>
			<td>for PCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fast SYBR Green Master Mix</td>
			<td style="width:133px;">ABI&#160;</td>
			<td style="width:157px;">4385612</td>
			<td>for qPCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">FirstChoice RLM-RACE Kit</td>
			<td style="width:133px;">Invitrogen</td>
			<td style="width:157px;">AM1700</td>
			<td>for 3&#39; UTR identification&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">MEGAscript T7 Transcription Kit</td>
			<td style="width:133px;">Invitrogen</td>
			<td style="width:157px;">AMB13345</td>
			<td>for dsRNA synthesis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TURBO DNase</td>
			<td style="width:133px;">Invitrogen</td>
			<td style="width:157px;">AM2239</td>
			<td>remove DNA template from dsRNA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TRIzol</td>
			<td style="width:133px;">Invitrogen</td>
			<td style="width:157px;">15596018</td>
			<td>for dsRNA or total RNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RQ1 RNase-Free Dnase</td>
			<td style="width:133px;">Promega</td>
			<td style="width:157px;">M6101</td>
			<td>remove DNA template from total RNA&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">chloroform&#160;</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">C2432</td>
			<td>for dsRNA or total RNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">2-Propanol</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">I9516</td>
			<td>for dsRNA or total RNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>24102</td>
			<td>for dsRNA or total RNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Diethyl pyrocarbonate, DEPC</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">D5758</td>
			<td>for RNase free water preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">glucose solution</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">G3285</td>
			<td>for lipoplexes preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride, NaCl</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">S7653</td>
			<td>insect saline buffer formula</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Potassium chloride, KCl</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">P9333</td>
			<td>insect saline buffer formula</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:352px;">Calcium chloride, CaCl2</td>
			<td>Sigma-Aldrich</td>
			<td>C1016</td>
			<td>insect saline buffer formula</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Magnesium chloride hexahydrate, MgCl2.6H2O</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">M2670</td>
			<td>insect saline buffer formula</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">EGTA&#160;</td>
			<td>Sigma-Aldrich</td>
			<td style="width:157px;">E3889</td>
			<td>enzyme inhibitor&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">dissecting scissor</td>
			<td style="width:133px;">F.S.T.</td>
			<td style="width:157px;"></td>
			<td>cockroach dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">fine tweezers</td>
			<td style="width:133px;">F.S.T.</td>
			<td style="width:157px;"></td>
			<td>cockroach dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">flexible tweezer</td>
			<td style="width:133px;">F.S.T.</td>
			<td style="width:157px;"></td>
			<td>cockroach holding&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pipetman</td>
			<td style="width:133px;">RAININ</td>
			<td style="width:157px;">P10</td>
			<td>sample preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">microcentrifuge tube</td>
			<td style="width:133px;">Axygen</td>
			<td>MCT175C, PCR02C</td>
			<td>sample preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">pipette tip&#160;</td>
			<td style="width:133px;">Axygen</td>
			<td></td>
			<td>sample preparation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">vortexter</td>
			<td style="width:133px;">Digisystem</td>
			<td style="width:157px;">vm1000</td>
			<td>sample preparation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Minispin centrifuge</td>
			<td style="width:133px;">The Gruffin Group</td>
			<td style="width:157px;">GMC 206</td>
			<td>for liquid spin down&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td style="width:133px;">ALC</td>
			<td style="width:157px;">PK121R</td>
			<td>sample preparation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pH meter&#160;</td>
			<td style="width:133px;">JENCO</td>
			<td style="width:157px;">6071</td>
			<td>for pH adjust</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">micro-volume spectrophotometer</td>
			<td style="width:133px;">Quawell</td>
			<td style="width:157px;">Q3000</td>
			<td>nucleic acid quantitative</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">PCR Thermal cycler</td>
			<td style="width:133px;">ABI&#160;</td>
			<td style="width:157px;">2720</td>
			<td>for template PCR or&#160; dsRNA synthesis incubation&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">quantitative real-time PCR</td>
			<td style="width:133px;">ABI&#160;</td>
			<td style="width:157px;">StepOne plus</td>
			<td>gene expression quantitative</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifugal Vacuum Concentrators</td>
			<td style="width:133px;">eppendorf</td>
			<td style="width:157px;">5301</td>
			<td>for dsRNA or total RNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Multipette&#160;</td>
			<td style="width:133px;">eppendorf</td>
			<td style="width:157px;">xstream</td>
			<td>for real-time PCR sample loading&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agarose I</td>
			<td style="width:133px;">amresco</td>
			<td style="width:157px;">0710</td>
			<td>for nucleic acid electrophoresis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">tub gene specfifc forward preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>GGG ACA AGC CGG AGT GCA GA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">tub gene specfifc reverse preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>TCC TGC TCC TGT CTC GCT GA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">dsTub template forward primer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>TAA TAC GAC TCA CTA TAG GGA CAA GCC GGA GTG CAG&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">dsTub template reverse primer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>TAA TAC GAC TCA CTA TAG GGT CCT GCT CCT GTC TCG CTG&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">dsEGFP template forward preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>TAA TAC GAC TCA CTA TAG GGT ATG GTG AGC AAG GGC GAG GAG</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">dsEGFP template reverse preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>TAA TAC GAC TCA CTA TAG GGT GGC GGA TCT TGA AGT TCA CC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">tub qPCR forward primer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>GGA CCG CAT CAG GAA ACT GGC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">tub qPCR reverse preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>CCA CAG ACA GCC TCT CCA TGA GC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">ef1 qPCR forward primer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>CGC TTG AGG AAA TCA AGA AGG A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">ef1 qPCRreverse preimer</td>
			<td style="width:133px;">tri-I biotech</td>
			<td style="width:157px;"></td>
			<td>CCT GCA GAG GAA GAC GAA G</td>
		</tr>
	</tbody>
</table>

practical use of rna interference: oral delivery of double-stranded rna in liposome carriers for cockroaches

RNA interference (RNAi) has been widely applied for uncovering the biological functions of numerous genes, and has been envisaged as a pest control tool operating by disruption of essential gene expression. Although different methods, such as injection, feeding, and soaking, have been reported for successful delivery of double-stranded RNA (dsRNA), the efficiency of RNAi through oral delivery of dsRNA is highly variable among different insect groups. The German cockroach, Blattella germanica, is highly sensitive to the injection of dsRNA, as shown by many studies published previously. The present study describes a method to demonstrate that the dsRNA encapsulated with liposome carriers is sufficient to retard the degradation of dsRNA by midgut juice. Notably, the continuous feeding of dsRNA encapsulated by liposomes significantly reduces the tubulin expression in the midgut, and led to the death of cockroaches. In conclusion, the formulation and utilization of dsRNA lipoplexes, which protect dsRNA against nucleases, could be a practical use of RNAi for insect pest control in the future.

A simplified scheme of the protocol for the oral delivery of dsRNA is presented in Figure 1, where the key steps for preparation of dsRNA lipoplexes are shown.
In order to investigate the protection given by liposome carriers upon dsRNA degradation in the midgut juice of B. germanica, an ex vivo assay where dsTub lipoplexes were incubated with midgut juice was conducted, and the in...

Watch this Scientific Journal Video about Practical Use of RNA Interference: Oral Delivery of Double-stranded RNA in Liposome Carriers for Cockroaches at JoVE.com

Practical Use of RNA Interference: Oral Delivery of Double-stranded RNA in Liposome Carriers for Cockroaches

This manuscript demonstrates the depletion of gene expression in the midgut of the German cockroach through oral ingestion of double-stranded RNA encapsulated in liposomes.

RNA interference (RNAi) has been widely applied for uncovering the biological functions of numerous genes, and has been envisaged as a pest control tool ...

The overall goal of this protocol is to deplete gene expression in the gut of cockroaches using RNA interference via oral ingestion of double-stranded RNA encapsulated in liposome carriers. This method can help answer key questions in the development of new pest control methods, such as can knocking down essential genes in the open field kill pests? The main advantage of this technique is that liposome protects the gene-specific double-stranded RNA to ensure its delivery to the target cell.Demonstrating the procedure will be Jia-Hsin Huang, a postdoc, and Yun Liu, a technician from my laboratory. To begin, anesthetize the cockroaches on ice until they do not move for three minutes. Then, pick up an insect using the thumb and index finger to access its ventral side.Next, use dissecting scissors to cut the tip of a coxa of a hind leg off between the coxa and the trochanter. Cutting elsewhere on the coxa is less efficient for the hemolymph collections. Now, position a 10-microliter micropipette at the incision, and squeeze the abdomen gently while drawing up the bleeding hemolymph.Repeat this process until the hemolymph from five cockroaches has been collected into a single microcentrifuge tube. Next, briefly spin down the pooled hemolymph for 10 seconds. Then, combine 10 microliters of hemolymph with 50 microliters of 1x insect saline buffer.Now, centrifuge the diluted hemolymph for 10 minutes to pull the hemocytes out of solution. Then, transfer the supernatant to a new tube. Lastly, quantify the total protein concentration using a microvolume UV-Vis spectrophotometer, and adjust the concentration of each sample to six milligrams of protein per microliter.To collect midgut juice, first, anesthetize the cockroaches on ice. Then, transfer one to a dissection plate loaded with cold 1x insect saline buffer, and use insect pins to secure it ventral side up. Now, dissect the abdomen using fine tweezers.Then, remove the entire gut, and transfer it to a fresh dish with 1x insect saline buffer. Next, isolate the midgut, which is the region between the crop and the Malpighian tubules. To do so, remove the front part of the animal and remove the hindgut.Next, quickly transfer the midgut to a microcentrifuge tube with 100 microliters of insect saline buffer. Collect the midguts from six cockroaches into the same tube. Then, vortex the tube for 10 seconds.Next, centrifuge the mixture for 10 minutes to separate out the hemocytes and gut tissues. Then, transfer the supernatant to a clean microcentrifuge tube, and adjust the concentration to six milligrams of protein per microliter. Double-stranded RNA lipoplexes must be used within an hour of preparation.During their preparation, be sure to combine all of the diluted reagent with the diluted double-stranded RNA at the same time. Then, quickly vortex and incubate the mixture. Once ready, mix four microliters of the double-stranded RNA solution with 10 microliters of insect saline buffer as a control, or mix it with 10 microliters of extracted enzymes taken from hemolymph or midgut juice.Next, make an enzyme-inhibited control by adding two microliters of EGTA. Otherwise, add two microliters of RNase-free water. Then, incubate the samples for an hour or longer at 25 degrees Celsius.After the incubation, add 200 microliters of extraction reagent and 40 microliters of chloroform, and then vortex. Next, centrifuge the samples for 10 minutes. Next, transfer 150 microliters of each supernatant to a new tube, and precipitate the double-stranded RNA from each sample by adding 150 microliters of isopropanol and incubating the samples on ice for 15 minutes.After the incubation, centrifuge the samples again and discard the supernatant. Then, wash the RNA pellets twice by adding 200 microliters of the 70%ethanol to each pellet and centrifuging the tube. After the second wash, dry the double-stranded RNA pellets using a centrifugal vacuum concentrator for three minutes.Then, resuspend the pellets in 10 microliters of RNase-free water. Finally, check the integrity of the treated double-stranded RNA using a 1.5%agarose gel. Feed the cockroaches twice per day, one hour after lights on and one hour before lights off.Do this for eight or 16 days without breaks. During this time, the cockroaches should be otherwise starved of water. For the feeding, have freshly prepared double-stranded RNA lipoplexes and naked double-stranded RNA available.For the bolus, use with four microliters of double-stranded RNA lipoplexes or 250 nanograms of naked double-stranded RNA. To feed a cockroach, first, grab it by the wings using flexible forceps. Do not grab the body parts of a cockroach.Then, slowly pipette the droplet of solution close to the mouthparts, and watch as the roach ingests the droplet. After the last feeding, provide water bottles to the roaches. Throughout the feeding period, assess the insects daily to check for mortality and remove any roaches that are no longer moving from the experiment.Continuous oral administration of double-stranded tub lipoplexes was able to decrease tubulin expression in the midgut from 40%at day nine to 60%at day 17. By comparison, naked double-stranded RNA had no effect. This is most likely due to finding that exposure of the naked double-stranded RNA to midgut juice resulted in degradation within an hour, whereas the liposome-conjugated double-stranded RNA remained stable.Not only did RNA levels decrease, but continuous feeding of the tubulin double-stranded RNA lipoplexes also resulted in significant lethality. This is unlikely to be due to the vector, as lipoplexes carrying double-stranded RNA to EGFP resulted in no lethality. While attempting this oral delivery system of RNA interference, it is important to perform a continuous feeding of double-stranded RNA for several days.Once mastery, the feeding step can be done in two minutes per insect if it is performed properly. If needed, different formulation of liposome nanoparticles can be applied to improve the feeding procedure and RNAi efficiency. Ultimately, this technique has made it feasible for researchers in the field of the pest management to explore new control strategies using RNAi.

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9.2K vues.  National Taiwan University. The overall goal of this protocol is to deplete gene expression in the gut of cockroaches using RNA interference via oral ingestion of double-stranded RNA encapsulated in liposome carriers. This method can help answer key questions in the development of new pest control methods, such as can knocking down essential genes in the open field kill pests? The main advantage of this technique is that liposome protects the gene-specific double-stranded RNA to ensure its delivery to the target cell.