Este estudo foi suportado por doações de Taiwan (Ministério da ciência e tecnologia, mais 100-2923-B-002-002-MY3 e 106-2313-B-002-011-MY3 para H.J.L.), República Checa (conceder a agência da Boémia do Sul, Universidade, Magali conceder 065/2017/P para Y.H.L) e Espanha ( Ministério da economia espanhola e competitividade, concede CGL2012-36251 e CGL2015-64727-P a X.B. e o governo catalão, conceder 2014 SGR 619 a X.B.); também recebeu apoio financeiro do Fundo Europeu para o desenvolvimento económico e Regional (fundos FEDER para X.B.).

1. síntese e preparação do dsRNA
<ol><li>Identifica os sites de destino do dsRNA da região untranslated 3' do gene-alvo. O dsTub é usado para o direcionamento do gene da α-tubulina (banheira) (número de adesão GenBank: KX228233), e dsEGFP como um controle negativo dsRNA destina-se a sequência de melhor proteína fluorescência verde (EGFP; Número de adesão GenBank: LC311024).</li>
	<li>Executar a amplificação por PCR padrão para sintetizar os modelos dsRNA com primers de gene-específico que contém a sequência de promotor T7 (5'-TAATACGACTCACTATAGGG-3'). As condições de amplificação do PCR e informações de primeira demão usados são aqueles relatados por Lin et al. (2017) 12 (ver Tabela de materiais).</li>
	<li>Prosseguir com a preparação do dsRNA usando uma transcrição de T7 Kit (veja a Tabela de materiais), seguindo as instruções do fabricante. Nota: Para produzir quantidade elevada dsRNA, misture duas reações em um tubo (no total 40 µ l) e incubar a 37 ° C durante a noite.</li>
	<li>Adicionar 2 µ l de DNase (ver Tabela de materiais) em amostras de dsRNA por 15 min a 37 ° C para digerir modelos de DNA.</li>
	<li>Adicionar o reagente de extração 200 µ l (veja a Tabela de materiais) e clorofórmio 40 µ l, então o vórtice.</li>
	<li>Centrifugar durante 10 min a 13.000 x g a 4 ° C e, em seguida, recolher o sobrenadante (150 µ l) em um novo tubo de microcentrifugadora.</li>
	<li>Precipitar dsRNA adicionando 150 µ l isopropanol e incubar por 15 min no gelo.</li>
	<li>Centrifugar por 15 min a 13.000 x g a 4 ° C e, em seguida, remover o sobrenadante.</li>
	<li>Adicione 200 µ l de etanol 70% para lavar dsRNA Pelotas. Centrifugação por 10min a 13.000 x g a 4 ° C.</li>
	<li>Remover o etanol e repita as etapas de lavagem do etanol.</li>
	<li>Remover o etanol e o pellet seco dsRNA por concentradores centrífugos de vácuo por 3 min, em seguida, resuspenda dsRNA com água livre de RNase.</li>
	<li>Determinar a quantidade do dsRNA purificada usando um espectrofotômetro UV-Vis de micro-volume (ver Tabela de materiais) de acordo com as instruções do fabricante e ajustar para a concentração desejada (por exemplo, 0,25 µ g / µ l para a preparação de lipoplexes dsRNA).</li>
	<li>Armazene as amostras de dsRNA a-20 ° C por até 3 meses.</li>
</ol>2. preparação do dsRNA Lipoplexes
<ol><li>Dilua 4 µ l de reagente de transfeccao (ver Tabela de materiais), adicionando 4 µ l de solução de glicose 5%. Dilua 4 µ l do dsRNA (1 µ g), adicionando 4 µ l de solução de glicose 5%.</li>
	<li>Adicione a solução de reagente diluído em lipossomas imediatamente na solução diluída dsRNA tudo de uma vez. Vórtice brevemente para misturá-los e, em seguida, incube por 15 min a 25 ° C. Nota: Não misture as soluções na ordem inversa.</li>
	<li>Os dsRNA lipoplexes estão prontas para uso. Use dentro de 1 hora de preparação e descartar depois de 1 hora. Nota: De acordo com as instruções do fabricante, os lipoplexes deve ser usado logo que possível.</li>
</ol>3. coleção de enzimas extracelulares de hemolinfa e suco Midgut
<ol><li>
Inseto tampão salino (estoque de x 10)
	<ol>
<li>Misture 900 mL de água bidestilada com 109,3 g NaCl, 15,7 g KCl, 6,3 g de CaCl2e 8,3 g MgCl2·6H2O.</li>
		<li>Ajustar o pH para 6,8 e preencher até 1.000 mL.</li>
	</ol>
</li>
	<li>
Coleção de hemolinfa
	<ol>
<li>Anestesia as baratas no gelo até que eles não se movem por 3 min.</li>
		<li>Segurar a barata com dois dedos (polegar e dedo indicador) e aparece do lado ventral da barata.</li>
		<li>Use a dissecação tesoura para cortar a ponta de uma coxa de uma pata traseira. Nota: Corte o cruzamento conectado entre a coxa e o trocânter. A excisão da outra parte da coxa foi menos eficiente para coletar a hemolinfa.</li>
		<li>Aperte o abdômen suavemente com o dedo médio e recolher a hemolinfa sangramento da incisão com uma micropipeta de 10 µ l.</li>
		<li>Piscina a hemolinfa de várias baratas (5 pessoas) em um tubo de microcentrifugadora. Nota: Manter os tubos microcentrifuga no gelo para evitar melanização. O volume médio de hemolinfa obtido de uma barata masculina é 2-3 µ l.</li>
		<li>Spin para baixo a hemolinfa brevemente com uma centrífuga de bancada de 10 s.</li>
		<li>Transferir o volume desejado de hemolinfa (ou seja, 10 µ l) e misturá-lo com 50 µ l de tampão salino inseto 1 de x.</li>
		<li>Centrifugação por 10min a 1.000 x g a 4 ° C a girar para baixo hemócitos. Transferi o sobrenadante para um tubo limpo microcentrifuga.</li>
		<li>Quantificar a concentração de proteína total usando um espectrofotômetro UV-Vis de micro-volume medindo A28015.</li>
		<li>Ajuste cada amostra para ter a mesma concentração de proteína (6 mg / µ l de proteínas totais).</li>
	</ol>
</li>
	<li>
Coleção de suco do intestino
	<ol>
<li>Anestesia as baratas no gelo. Arrumar as baratas lado ventral na placa de dissecação com insetos tampão salino de frio 1x usando pinos de insetos.</li>
		<li>Disse o abdômen com uma pinça fina. Remova o intestino inteiro (incluindo o intestino frontal, meados e patas traseiro) para um prato fresco com 1x tampão salino de insetos.</li>
		<li>Remover o intestino dianteiro e traseiro e transferir rapidamente o intestino para um tubo de microcentrifugadora que contém o tampão salino inseto de 100 µ l.</li>
		<li>Piscina do midguts de seis baratas no mesmo tubo e vórtice por 10 s.</li>
		<li>Centrifugação por 10min a 1.000 x g a 4 ° C a girar para baixo o hemócitos e tecidos do intestino. Transferi o sobrenadante para um tubo limpo microcentrifuga.</li>
		<li>Quantificar a concentração de proteína total usando um espectrofotômetro UV-Vis de micro-volume medindo A28015.</li>
		<li>Ajuste cada amostra para ter a mesma concentração de proteína (6 mg / µ l de proteínas totais).</li>
	</ol>
</li>
</ol>4. dsRNA ensaio de degradação
<ol><li>Recentemente a preparar 4 µ l do dsRNA nua ou lipoplexes dsRNA (1 µ g).</li>
	<li>Misture dsRNA enzimas de soluções com 10 µ l de tampão salino de insetos (controle), extraídas de hemolinfa, ou intestino suco.</li>
	<li>Adicione 2 µ l de EGTA (20mm) ou água livre de RNase para separar amostras como controles para inibição de actividades enzimáticas.</li>
	<li>Incubar durante 1 hora ou mais (6, 12 ou 24 horas) a 25 ° C.</li>
	<li>Adicione 200 µ l extração reagente e clorofórmio 40 µ l, então o vórtice.</li>
	<li>Centrifugar durante 10 min a 13.000 x g a 4 ° C e, em seguida, recolher o sobrenadante (150 µ l) em um novo tubo de microcentrifugadora.</li>
	<li>Precipitar dsRNA adicionando 150 µ l isopropanol e incubar por 15 min no gelo.</li>
	<li>Centrifugar por 15 min a 13.000 x g a 4 ° C e, em seguida, remover o sobrenadante.</li>
	<li>Adicione 200 µ l de etanol 70% para lavar dsRNA Pelotas. Centrifugação por 10min a 13.000 x g a 4 ° C.</li>
	<li>Remover o etanol e repita as etapas de lavagem do etanol.</li>
	<li>Remova o etanol e o pellet seco dsRNA por concentradores de vácuo centrífugas para 3 min. Ressuspender dsRNA com água livre de RNase a µ l 10.</li>
	<li>Verificar a integridade do dsRNA Tratado através de eletroforese em gel em um gel de agarose 1,5%.</li>
</ol>5. oral administração do dsRNA
<ol><li>Manter as baratas em uma dieta ad libitum do alimento seco (comida). Priva o abastecimento de água desde as baratas um dia antes experimentos de ingestão do dsRNA.</li>
	<li>Segure uma barata, agarrando suas asas com as pinças flexíveis (Figura 1, passo 5). Nota: Não pegue as partes do corpo das baratas.</li>
	<li>Prepare o dsRNA lipoplexes, bem como dsRNA nua, para a alimentação, conforme descrito na seção 2. Nota: O dsRNA lipoplexes deve ser preparado na hora antes da alimentação.</li>
	<li>Alimentar 4 µ l de lipoplexes dsRNA ou nu dsRNA (250 ng) com uma micropipeta.</li>
	<li>Lentamente, pipetar a gota da solução dsRNA perto o aparelho bucal de baratas e deixe as baratas ingerir a gota completamente.</li>
	<li>Realizar os experimentos de ingestão de duas vezes por dia (1h Após luzes acesas e 1h antes de luzes apagadas) por 8 dias ou 16 dias continuamente. Nota: Todas as baratas adquiriram água apenas através de alimentação manual com reagentes dsRNA solução ou controle (por exemplo, água livre de nuclease, solução de glicose e reagente lipossoma) durante experimentos de ingestão.</li>
	<li>Fornecem garrafas de água para as baratas após 16 dias de ingestão das experiências de dsRNA.</li>
</ol>6. avaliar Knockdown
<ol><li>No tempo escolhido pontos (2, 9 e 17 dias depois do ensaio de ingestão do dsRNA), coletar os insetos dsEGFP - e dsTub-tratada e dissecar os tecidos escolhidos (por exemplo, intestino).</li>
	<li>Realize o PCR quantitativo em tempo real (qRT-PCR). As condições de amplificação de qRT-PCR e informações da primeira demão, conforme relatado por Lin et al. (2017) 12.</li>
	<li>Avalie o controle e o dsRNA-tratados insetos diariamente para verificar a mortalidade e remover as baratas que já não se move.</li>
</ol>

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Este protocolo apresenta um método para RNAi eficaz através de entrega oral dos lipoplexes dsRNA, envolvendo proteção contra digestão ribonuclease no suco de intestino da barata alemão. Como mostrado em outros estudos em várias espécies de insetos, o efeito de RNAi pobre através de entrega oral do dsRNA principalmente é contabilizado pela degradação de dsRNA8,9,10. Este protocolo produz lipossomas que servem como pro...

RNAi tem sido demonstrado como um método eficaz para a expressão do gene "knockdown" através de um mecanismo de uma via de silenciamento pós-transcricional desencadeada por moléculas de dsRNA em muitos eucariotos1. Durante a última década de estudo, RNAi tornou-se uma ferramenta útil para estudar as funções dos genes de desenvolvimento para o comportamento por esgotar a expressão de genes específicos, através da injeção e/ou alimentação do dsRNA em vários táxons de insetos2,3. Devido a especificidade e a robustez do efeito de esgotamento, a aplicação de RNAi atualmente está sendo considerada como uma estratégia potencial para controle de pragas de gestão4,5. No entanto, a eficiência de RNAi varia amplamente entre as espécies de insetos, consoante os diferentes genes alvo e os métodos de entrega. Um corpo crescente de evidências sugere que a instabilidade do dsRNA, que é degradada por ribonucleases, é um fator crítico na eficácia limitada de RNAi5,6. Por exemplo, a baixa sensibilidade de RNAi em Manduca sexta foi explicada pelo fato de que o dsRNA misturado com hemolinfa foi rapidamente degradado dentro de 1 hora,7. Da mesma forma, a presença de nucleases alcalinas no intestino, que eficientemente degradar dsRNA ingerido, é fortemente correlacionada com baixa eficiência de RNAi em diferentes ordens de insetos8,9,10.
A entrega oral de dsRNA é particularmente interessante para a aplicação de RNAi em uma estratégia de controle de pragas, mas um método para retardar a degradação do dsRNA pelas nucleases no intestino ainda não foi desenvolvido, que teria potencial para assegurar a eficaz RNAi através da alimentação. No entanto, a apatia de RNAi para entrega oral do dsRNA foi relatada por alimentação grande quantidade de dsRNA, por exemplo, 50 µ g/ml Bombyx mori, ou continuamente alimentando por 8 dias (8 µ g dsRNA no total) das espécies de gafanhoto. A baratinha, Blattella germinica, é altamente sensível a RNAi através da injeção de dsRNA11,12,13,14, mas não é responsiva ao dsRNA através da alimentação. Recentemente, Lin et al. (2017) demonstraram que o dsRNA encapsulados com resultados de transportadoras em lipossomas em RNAi bem sucedida a nocaute a expressão do gene α-tubulina no intestino e gatilho mortalidade significativa da baratinha15. Como a degradação do dsRNA no intestino é o fator limitante para RNAi oral, os portadores de lipossoma servem como um veículo para proteger dsRNA de degradação, que é facilmente aplicável em outros insetos com atividades de nuclease forte no intestino. Digno de nota, o motivo para a escolha do reagente de transfeccao particular (ver Tabela de materiais) usamos como portador de lipossomas no atual protocolo é que ele foi testado para transfeccao de linha celular inseto com menor toxicidade, de acordo com o instruções do fabricante. De acordo com a comparação dos sistemas de transfeccao lipossoma diferentes no guerreiro et al (2013) 16, a eficiência do transfecting RNA de interferência pequeno (siRNA) é aproximadamente o mesmo entre este e a outros sistemas disponíveis comercialmente que têm sido utilizados para sistemas de entrega dsRNA em outros insetos17,18 . Além disso, nosso método de alimentação é cuidadoso o suficiente para garantir a quantidade adequada de dsRNA é ingerida por cada barata, e que os resultados são robustos e confirmado. Em resumo, o presente protocolo e os resultados demonstram que usar dsRNA lipoplexes melhora a estabilidade do dsRNA e abre as portas para o design da entrega oral estratégia de RNAi, que é uma abordagem promissora para controle de pragas no futuro.

<table><tbody><tr><td>GenJe Plus DNA in vitro Transfection reagent</td><td>SignaGen</td><td>SL100499</td><td>for lipoplexes preparation</td></tr><tr><td>Blend Taq plus</td><td>TOYOBO&amp;nbsp;</td><td>BTQ-201</td><td>for PCR</td></tr><tr><td>Fast SYBR Green Master Mix</td><td>ABI&amp;nbsp;</td><td>4385612</td><td>for qPCR</td></tr><tr><td>FirstChoice RLM-RACE Kit</td><td>Invitrogen</td><td>AM1700</td><td>for 3&#039; UTR identification&amp;nbsp;</td></tr><tr><td>MEGAscript T7 Transcription Kit</td><td>Invitrogen</td><td>AMB13345</td><td>for dsRNA synthesis</td></tr><tr><td>TURBO DNase</td><td>Invitrogen</td><td>AM2239</td><td>remove DNA template from dsRNA</td></tr><tr><td>TRIzol</td><td>Invitrogen</td><td>15596018</td><td>for dsRNA or total RNA extraction</td></tr><tr><td>RQ1 RNase-Free Dnase</td><td>Promega</td><td>M6101</td><td>remove DNA template from total RNA&amp;nbsp;</td></tr><tr><td>chloroform&amp;nbsp;</td><td>Sigma-Aldrich</td><td>C2432</td><td>for dsRNA or total RNA extraction</td></tr><tr><td>2-Propanol</td><td>Sigma-Aldrich</td><td>I9516</td><td>for dsRNA or total RNA extraction</td></tr><tr><td>ethanol</td><td>Sigma-Aldrich</td><td>24102</td><td>for dsRNA or total RNA extraction</td></tr><tr><td>Diethyl pyrocarbonate, DEPC</td><td>Sigma-Aldrich</td><td>D5758</td><td>for RNase free water preparation</td></tr><tr><td>glucose solution</td><td>Sigma-Aldrich</td><td>G3285</td><td>for lipoplexes preparation</td></tr><tr><td>Sodium chloride, NaCl</td><td>Sigma-Aldrich</td><td>S7653</td><td>insect saline buffer formula</td></tr><tr><td>Potassium chloride, KCl</td><td>Sigma-Aldrich</td><td>P9333</td><td>insect saline buffer formula</td></tr><tr><td>Calcium chloride, CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>C1016</td><td>insect saline buffer formula</td></tr><tr><td>Magnesium chloride hexahydrate, MgCl&lt;sub&gt;2&lt;/sub&gt;.6H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>M2670</td><td>insect saline buffer formula</td></tr><tr><td>EGTA&amp;nbsp;</td><td>Sigma-Aldrich</td><td>E3889</td><td>enzyme inhibitor&amp;nbsp;</td></tr><tr><td>dissecting scissor</td><td>F.S.T.</td><td></td><td>cockroach dissection</td></tr><tr><td>fine tweezers</td><td>F.S.T.</td><td></td><td>cockroach dissection</td></tr><tr><td>flexible tweezer</td><td>F.S.T.</td><td></td><td>cockroach holding&amp;nbsp;</td></tr><tr><td>pipetman</td><td>RAININ</td><td>P10</td><td>sample preparation</td></tr><tr><td>microcentrifuge tube</td><td>Axygen</td><td>MCT175C, PCR02C</td><td>sample preparation</td></tr><tr><td>pipette tip&amp;nbsp;</td><td>Axygen</td><td></td><td>sample preparation</td></tr><tr><td>vortexter</td><td>Digisystem</td><td>vm1000</td><td>sample preparation</td></tr><tr><td>Minispin centrifuge</td><td>The Gruffin Group</td><td>GMC 206</td><td>for liquid spin down&amp;nbsp;</td></tr><tr><td>Centrifuge</td><td>ALC</td><td>PK121R</td><td>sample preparation</td></tr><tr><td>pH meter&amp;nbsp;</td><td>JENCO</td><td>6071</td><td>for pH adjust</td></tr><tr><td>micro-volume spectrophotometer</td><td>Quawell</td><td>Q3000</td><td>nucleic acid quantitative</td></tr><tr><td>PCR Thermal cycler</td><td>ABI&amp;nbsp;</td><td>2720</td><td>for template PCR or&amp;nbsp; dsRNA synthesis incubation&amp;nbsp;</td></tr><tr><td>quantitative real-time PCR</td><td>ABI&amp;nbsp;</td><td>StepOne plus</td><td>gene expression quantitative</td></tr><tr><td>Centrifugal Vacuum Concentrators</td><td>eppendorf</td><td>5301</td><td>for dsRNA or total RNA extraction</td></tr><tr><td>Multipette&amp;nbsp;</td><td>eppendorf</td><td>xstream</td><td>for real-time PCR sample loading&amp;nbsp;</td></tr><tr><td>Agarose I</td><td>amresco</td><td>0710</td><td>for nucleic acid electrophoresis</td></tr><tr><td>tub gene specfifc forward preimer</td><td>tri-I biotech</td><td></td><td>GGG ACA AGC CGG AGT GCA GA</td></tr><tr><td>tub gene specfifc reverse preimer</td><td>tri-I biotech</td><td></td><td>TCC TGC TCC TGT CTC GCT GA</td></tr><tr><td>dsTub template forward primer</td><td>tri-I biotech</td><td></td><td>TAA TAC GAC TCA CTA TAG GGA CAA GCC GGA GTG CAG&amp;nbsp;</td></tr><tr><td>dsTub template reverse primer</td><td>tri-I biotech</td><td></td><td>TAA TAC GAC TCA CTA TAG GGT CCT GCT CCT GTC TCG CTG&amp;nbsp;</td></tr><tr><td>dsEGFP template forward preimer</td><td>tri-I biotech</td><td></td><td>TAA TAC GAC TCA CTA TAG GGT ATG GTG AGC AAG GGC GAG GAG</td></tr><tr><td>dsEGFP template reverse preimer</td><td>tri-I biotech</td><td></td><td>TAA TAC GAC TCA CTA TAG GGT GGC GGA TCT TGA AGT TCA CC</td></tr><tr><td>tub qPCR forward primer</td><td>tri-I biotech</td><td></td><td>GGA CCG CAT CAG GAA ACT GGC</td></tr><tr><td>tub qPCR reverse preimer</td><td>tri-I biotech</td><td></td><td>CCA CAG ACA GCC TCT CCA TGA GC</td></tr><tr><td>ef1 qPCR forward primer</td><td>tri-I biotech</td><td></td><td>CGC TTG AGG AAA TCA AGA AGG A</td></tr><tr><td>ef1 qPCRreverse preimer</td><td>tri-I biotech</td><td></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 de interferência (RNAi) tem sido aplicado extensamente para descobrir as funções biológicas de numerosos genes e foi previsto como uma praga controle ferramenta de exploração por perturbação da expressão do gene essencial. Embora diferentes métodos, tais como a injeção, alimentação e imersão, têm sido relatados para entrega bem sucedida de RNA double-stranded (dsRNA), a eficiência de RNAi através de entrega oral do dsRNA é altamente variável entre os diferentes grupos de insetos. A baratinha, Blattella germanica, é altamente sensível à injecção de dsRNA, como mostrado por muitos estudos publicados anteriormente. O presente estudo descreve um método para demonstrar que o dsRNA encapsulado com transportadoras em lipossomas é suficiente para retardar a degradação do dsRNA por suco de intestino. Notavelmente, a alimentação contínua do dsRNA encapsulado por lipossomas significativamente reduz a expressão de tubulina no intestino e levou à morte de baratas. Em conclusão, a formulação e utilização dos lipoplexes dsRNA, que protegem o dsRNA contra nucleases, poderiam ser um uso prático de RNAi para controle de pragas de insetos no futuro.

Um esquema simplificado do protocolo de entrega oral do dsRNA é apresentado na Figura 1, onde as principais etapas para a preparação dos lipoplexes dsRNA são mostradas.
A fim de investigar a protecção dada pelas transportadoras em lipossomas em cima dsRNA degradação no suco de intestino de b. germanica, um ensaio ex vivo , onde foi realizado o dsTub lipoplexes foram incubad...

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

Uso prático da interferência do RNA: Oral entrega de RNA Double-stranded em lipossomas transportadoras para baratas

Este manuscrito demonstra o esgotamento de expressão gênica no intestino da barata alemão através da ingestão oral de RNA double-stranded encapsulada em lipossomas.

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

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JoVE Journal

Biology

9.3K visualizações.  National Taiwan University. Este manuscrito demonstra o esgotamento de expressão gênica no intestino da barata alemão através da ingestão oral de RNA double-stranded encapsulada em lipossomas.

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

Double-stranded RNA Oral Delivery Methods to Induce RNA Interference in Phloem and Plant-sap-feeding Hemipteran Insects

Phloem and plant sap feeding insects invade the integrity of crops and fruits to retrieve nutrients, in the process damaging food crops. Hemipteran insects account for a number of economically substantial pests of plants that cause damage to crops by feeding on phloem sap. The brown marmorated stink bug (BMSB), Halyomorpha halys (Heteroptera: Pentatomidae) and the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae) are hemipteran insect pests introduced in North America, where they are an invasive agricultural pest of high-value specialty, row, and staple crops and citrus fruits, as well as a nuisance pest when they aggregate indoors. Insecticide resistance in many species has led to the development of alternate methods of pest management strategies. Double-stranded RNA (dsRNA)-mediated RNA interference (RNAi) is a gene silencing mechanism for functional genomic studies that has potential applications as a tool for the management of insect pests. Exogenously synthesized dsRNA or small interfering RNA (siRNA) can trigger highly efficient gene silencing through the degradation of endogenous RNA, which is homologous to that presented. Effective and environmental use of RNAi as molecular biopesticides for biocontrol of hemipteran insects requires the in vivo delivery of dsRNAs through feeding. Here we demonstrate methods for delivery of dsRNA to insects: loading of dsRNA into green beans by immersion, and absorbing of gene-specific dsRNA with oral delivery through ingestion. We have also outlined non-transgenic plant delivery approaches using foliar sprays, root drench, trunk injections as well as clay granules, all of which may be essential for sustained release of dsRNA. Efficient delivery by orally ingested dsRNA was confirmed as an effective dosage to induce a significant decrease in expression of targeted genes, such as juvenile hormone acid O-methyltransferase (JHAMT) and vitellogenin (Vg). These innovative methods represent strategies for delivery of dsRNA to use in crop protection and overcome environmental challenges for pest management.

This article demonstrates novel techniques developed for oral delivery of double-stranded RNA (dsRNA) through the vascular tissues of plants for RNA interference (RNAi) in phloem sap feeding insects.

Métodos de entrega Double-stranded RNA Oral para induzir a interferência do RNA no floema e insetos Hemipteran planta-sap-alimentação

Phloem and plant sap feeding insects invade the integrity of crops and fruits to retrieve nutrients, in the process damaging food crops. Hemipteran ...

Ambiente

Reproducible dsRNA Microinjection and Oviposition Bioassay in Mosquitoes and House Flies

Synthetic dsRNAs, used to induce RNA interference, may have dose dependent phenotypic effects. These effects are difficult to define if the dsRNAs are delivered using a non-quantitative method. Accurate delivery of known quantities of nucleic acids or other chemicals is critical to measure the efficacy of the compound being tested and to allow reliable comparison between compounds.
Here we provide a reproducible, quantitative microinjection protocol that ensures accurate delivery of specific doses of dsRNA, reducing the mortality typically induced by injection injury. These modifications include the addition of Rhodamine B, a graduated injection needle, and an improved recovery method borrowed from Isoe and Collins. This method allows calculation of dose responses and facilitates comparisons between compounds. Versions of this method have been successfully used on three genera of mosquitoes as well as house flies to assess the reduction in fecundity resulting from gene silencing of ribosomal RNA transcripts.
This protocol provides strategies to reduce several challenges of small insect microinjection. Together, mechanical delivery of dsRNAs accompanied by visual verification, identification of effective locations for delivery, and inclusion of a post-injection recovery period ensure accurate dosing and low injury mortality. This protocol also describes an oviposition bioassay for uniform determination of effects on fecundity.

This protocol describes a microinjection methodology that we have standardized and used for several years to deliver specific quantities of nucleic acids directly to the hemolymph of mosquitoes and house flies. This protocol results in minimal injection mortality and allows dose correlated measurements of fecundity.

Reprodutível dsRNA Microinjection e Bioassay de oviposição em mosquitos e moscas domésticas

Synthetic dsRNAs, used to induce RNA interference, may have dose dependent phenotypic effects. These effects are difficult to define if the dsRNAs are ...

RNA Interference in Aquatic Beetles as a Powerful Tool for Manipulating Gene Expression at Specific Developmental Time Points

RNA interference (RNAi) remains a powerful technique that allows for the targeted reduction of gene expression through mRNA degradation. This technique is applicable to a wide variety of organisms and is highly efficient in the species-rich order Coleoptera (beetles). Here, we summarize the necessary steps for developing this technique in a novel organism and illustrate its application to the different developmental stages of the aquatic diving beetle Thermonectus marmoratus. Target gene sequences can be obtained cost-effectively through the assembly of transcriptomes against a close relative with known genomics or de novo. Candidate gene cloning utilizes a specific cloning vector (the pCR4-TOPO plasmid), which allows the synthesis of double-stranded RNA (dsRNA) for any gene with the use of a single common primer. The synthesized dsRNA can be injected into either embryos for early developmental processes or larvae for later developmental processes. We then illustrate how RNAi can be injected into aquatic larvae using immobilization in agarose. To demonstrate the technique, we provide several examples of RNAi experiments, generating specific knockdowns with predicted phenotypes. Specifically, RNAi for the tanning gene laccase2 leads to cuticle lightening in both larvae and adults, and RNAi for the eye pigmentation gene white produces a lightening/lack of pigmentation in eye tubes. In addition, the knockdown of a key lens protein leads to larvae with optical deficiencies and a reduced ability to hunt prey. Combined, these results exemplify the power of RNAi as a tool for investigating both morphological patterning and behavioral traits in organisms with only transcriptomic databases.

RNA interference is a widely applicable, powerful technique for manipulating gene expression at specific developmental stages. Here, we describe the necessary steps for implementing this technique in the aquatic diving beetle Thermonectus marmoratus, from the acquisition of gene sequences to the knockdown of genes that affect structure or behavior.

Interferência de RNA em besouros aquáticos como uma poderosa ferramenta para manipular a expressão genética em pontos de tempo específicos de desenvolvimento

RNA interference (RNAi) remains a powerful technique that allows for the targeted reduction of gene expression through mRNA degradation. This technique is ...

Applications of RNA Interference in American Cockroach

Cockroaches, a sanitary pest, are essential species in insect developmental and metamorphic studies due to their easy feeding and hemimetabolous characteristics. Altogether with well-annotated genome sequences, these advantages have made American cockroach, Periplaneta americana, an important hemimetabolous insect model. Limited by the shortage of knockout strategy, effective RNA interference (RNAi)-based gene knockdown becomes an indispensable technique in functional gene research of P. americana. The present protocol describes the RNAi operation techniques in P. americana. The protocol includes (1) selection of the P. americana at proper developmental stages, (2) preparation for the injection setting, (3) dsRNA injection, and (4) gene knockdown efficiency detection. RNAi is a powerful reverse genetic tool in P. americana. The majority of P. americana tissues are sensitive to extracellular dsRNA. Its simplicity allows researchers to quickly obtain dysfunctional phenotypes under one or multiple targeting dsRNA injections, enabling researchers to better use the P. americana for developmental and metamorphic studies.

The present protocol describes step-by-step guidelines for the RNAi operation techniques in P. americana.

Aplicações de interferência de RNA na barata americana

Cockroaches, a sanitary pest, are essential species in insect developmental and metamorphic studies due to their easy feeding and hemimetabolous ...

Biologia do Desenvolvimento

RNAi Interference by dsRNA Injection into Drosophila Embryos

Genetic screening is one of the most powerful methods available for gaining insights into complex biological process 1. Over the years many improvements and tools for genetic manipulation have become available in Drosophila 2. Soon after the initial discovery by Frie and Mello 3 that double stranded RNA can be used to knockdown the activity of individual genes in Caenorhabditis elegans, RNA interference (RNAi) was shown to provide a powerful reverse genetic approach to analyze gene functions in Drosophila organ development 4, 5.
Many organs, including lung, kidney, liver, and vascular system, are composed of branched tubular networks that transport vital fluids or gases 6, 7. The analysis of Drosophila tracheal formation provides an excellent model system to study the morphogenesis of other tubular organs 8. The Berkeley Drosophila genome project has revealed hundreds of genes that are expressed in the tracheal system. To study the molecular and cellular mechanism of tube formation, the challenge is to understand the roles of these genes in tracheal development. Here, we described a detailed method of dsRNA injection into Drosophila embryo to knockdown individual gene expression. We successfully knocked down endogenous dysfusion(dys) gene expression by dsRNA injection. Dys is a bHLH-PAS protein expressed in tracheal fusion cells, and it is required for tracheal branch fusion 9, 10. dys-RNAi completely eliminated dys expression and resulted in tracheal fusion defect. This relatively simple method provides a tool to identify genes requried for tissure and organ development in Drosophila.

RNAi Interference by dsRNA Injection into Drosophila Embryos

RNA interference has been proven very effective to analyze gene function in Drosophila tracheal development. A detailed protocol used by Jiang lab to inject dsRNA into fly embryos to knockdown gene expression is illustrated. This technique has the potential for screening genes required for tissue and organ development in Drosophila.

RNAi Interferência por injeção dsRNA em Drosophila Os embriões

Genetic screening is one of the most powerful methods available for gaining insights into complex biological process 1. Over the years many improvements ...

Biologia

Chitosan/Interfering RNA Nanoparticle Mediated Gene Silencing in Disease Vector Mosquito Larvae

Vector mosquitoes inflict more human suffering than any other organism&#8212;and kill more than one million people each year. The mosquito genome projects facilitated research in new facets of mosquito biology, including functional genetic studies in the primary African malaria vector Anopheles gambiae and the dengue and yellow fever vector Aedes aegypti. RNA interference- (RNAi-) mediated gene silencing has been used to target genes of interest in both of these disease vector mosquito species. Here, we describe a procedure for preparation of chitosan/interfering RNA nanoparticles that are combined with food and ingested by larvae. This technically straightforward, high-throughput, and relatively inexpensive methodology, which is compatible with long double stranded RNA (dsRNA) or small interfering RNA (siRNA) molecules, has been used for the successful knockdown of a number of different genes in A. gambiae and A. aegypti larvae. Following larval feedings, knockdown, which is verified through qRT-PCR or in situ hybridization, can persist at least through the late pupal stage. This methodology may be applicable to a wide variety of mosquito and other insect species, including agricultural pests, as well as other non-model organisms. In addition to its utility in the research laboratory, in the future, chitosan, an inexpensive, non-toxic and biodegradable polymer, could potentially be utilized in the field.

Here we describe a procedure for inhibiting gene function in disease vector mosquitoes through the use of chitosan/interfering RNA nanoparticles that are ingested by larvae.

A quitosana / RNA de interferência Nanoparticle Mediated silenciamento gênico na Doença Vector Mosquito Larvas

Vector mosquitoes inflict more human suffering than any other organism&#8212;and kill more than one million people each year. The mosquito genome projects ...

Effective Oral RNA Interference (RNAi) Administration to Adult Anopheles gambiae Mosquitoes

RNA interference has been a heavily utilized tool for reverse genetic analysis for two decades. In adult mosquitoes, double-stranded RNA (dsRNA) administration has been accomplished primarily via injection, which requires significant time and is not suitable for field applications. To overcome these limitations, here we present a more efficient method for robust activation of RNAi by oral delivery of dsRNA to adult Anopheles gambiae. Long dsRNAs were produced in Escherichia coli strain HT115 (DE3), and a concentrated suspension of heat-killed dsRNA-containing bacteria in 10% sucrose was offered on cotton balls ad-libitum to adult mosquitoes. Cotton balls were replaced every 2 days for the duration of the treatment. Use of this method to target doublesex (a gene involved in sex differentiation) or fork head (which encodes a salivary gland transcription factor) resulted in reduced target gene expression and/or protein immunofluorescence signal, as measured by quantitative Real-Time PCR (qRT-PCR) or fluorescence confocal microscopy, respectively. Defects in salivary gland morphology were also observed. This highly flexible, user-friendly, low-cost, time-efficient method of dsRNA delivery could be broadly applicable to target genes important for insect vector physiology and beyond.

Effective Oral RNA Interference RNAi Administration to Adult Anopheles gambiae Mosquitoes

The oral administration of dsRNA produced by bacteria, a delivery method for RNA interference (RNAi) that is routinely used in Caenorhabditis elegans, was successfully applied here to adult mosquitoes. Our method allows for robust reverse genetics studies and transmission-blocking vector studies without the use of injection.

Administração eficaz de interferência oral de RNA (RNAi) para mosquitos anofeeles gâmbias adultos

RNA interference has been a heavily utilized tool for reverse genetic analysis for two decades. In adult mosquitoes, double-stranded RNA (dsRNA) ...

Application of RNA Interference in the Pinewood Nematode, Bursaphelenchus xylophilus

The pinewood nematode, Bursaphelenchus xylophilus, is one of the most destructive invasive species worldwide, causing the wilting and eventual death of pine trees. Despite the recognition of their economic and environmental significance, it has thus far been impossible to study the detailed gene functions of plant-parasitic nematodes (PPNs) using conventional forward genetics and transgenic methods. However, as a reverse genetics technology, RNA interference (RNAi) facilitates the study of the functional genes of nematodes, including B. xylophilus. 
This paper outlines a new protocol for RNAi of the ppm-1 gene in B. xylophilus, which has been reported to play crucial roles in the development and reproduction of other pathogenic nematodes. For RNAi, the T7 promoter was linked to the 5&#8242;-terminal of the target fragment by polymerase chain reaction (PCR), and double-stranded RNA (dsRNA) was synthesized by in vitro transcription. Subsequently, dsRNA delivery was accomplished by soaking the nematodes in a dsRNA solution mixed with synthetic neurostimulants. Synchronized juveniles of B. xylophilus (approximately 20,000 individuals) were washed and soaked in dsRNA (0.8 &#181;g/mL) in the soaking buffer for 24 h in the dark at 25 &#176;C.
The same quantity of nematodes was placed in a soaking buffer without dsRNA as a control. Meanwhile, another identical quantity of nematodes was placed in a soaking buffer with green fluorescent protein (gfp) gene dsRNA as a control. After soaking, the expression level of the target transcripts was determined using real-time quantitative PCR. The effects of RNAi were then confirmed using microscopic observation of the phenotypes and a comparison of the body size of the adults among the groups. The current protocol can help advance research to better understand the functions of the genes of B. xylophilus and other parasitic nematodes toward developing control strategies through genetic engineering.

Application of RNA Interference in the Pinewood Nematode, Bursaphelenchus xylophilus

Here, we introduce a detailed soaking method of RNA interference in Bursaphelenchus xylophilus to facilitate the study of gene functions.

Aplicação de interferência de RNA no Nematode pinewood, Bursaphelenchus xylophilus

The pinewood nematode, Bursaphelenchus xylophilus, is one of the most destructive invasive species worldwide, causing the wilting and eventual death of ...

Técnicas avançadas de RNAi em Trichogramma dendrolimi para análise da função gênica

RNA Interference in the Egg Parasitoid, Trichogramma dendrolimi Matsumura

The egg parasitoids, Trichogramma spp, are recognized as efficient biological control agents against various lepidopteran pests in agriculture and forests. The immature stages of Trichogramma offspring develop within the host egg, exhibiting remarkable diminutiveness (approximately 0.5 mm in adult length). RNA-interference (RNAi) methodology has emerged as a crucial tool for elucidating gene functions in numerous organisms. However, manipulating RNAi in certain small parasitoid species, such as Trichogramma, has generally posed significant challenges. In this study, we present an efficient RNAi method in Trichogramma denrolimi. The outlined procedure encompasses the acquisition and isolation of individual T. dendrolimi specimens from host eggs, the design and synthesis of double-stranded RNA (dsRNA), the in vitro transplantation and cultivation of T. dendrolimi pupae, the micro-injection of dsRNA, and the subsequent assessment of target gene knockdown through RT-qPCR analysis. This study furnishes a comprehensive, visually detailed procedure for conducting RNAi experiments in T. dendrolimi, thereby enabling researchers to investigate the gene regulation in this species. Furthermore, this methodology is adaptable for RNAi studies or micro-injections in other Trichogramma species with minor adjustments, rendering it a valuable reference for conducting RNAi experiments in other endoparasitic species.

Autor em destaque: Investigando a partenogênese Thelytokous induzida por Wolbachia e o desenvolvimento do kit de ferramentas genéticas por meio da interferência de RNA

The manipulation of RNA interference (RNAi) presents a formidable challenge in many parasitoid species with diminutive size, such as Trichogramma wasps. This study delineated an efficient RNAi method in Trichogramma denrolimi. The present methodology provides a robust model for investigating gene regulation in Trichogramma wasps.