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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 ...

National Taiwan University

Czech Academy of Sciences

University of South Bohemia

We report the synthesis and structural characterization of two dumbbell-shaped dendrimers incorporating 9-phenylcarbazole units as dendrons, as well as their thermal, morphological, photophysical, and electrochemical properties.

Synthesis and properties of dumbbell-shaped dendrimers containing 9-phenylcarbazole dendrons.

Covalent linkage of dendritic carbazole-based donors and 1,3,4-oxdiazole-based acceptors renders novel bipolar dendrimers that can efficiently facilitate the photoinduced electron transfer (PET) process. Photodynamic studies indicated that the PET rate of bipolar dendrimers DA1 and DA2 can be modulated by the number of acceptors presented in the molecule.

Modulate photoinduced electron transfer efficiency of bipolar dendritic systems.

The daily susceptibility rhythm to permethrin and the expression level of the delta class glutathione S-transferase (BgGSTD1) gene were investigated in Blattella germanica. Male cockroaches were exposed to the same concentration of permethrin at different times in a light-dark cycle, and results showed that the highest resistance occurred at night. Furthermore, the circadian rhythmicity of permethrin susceptibility was demonstrated by the highest resistance at subjective night under constant darkness. The mRNA level of the BgGSTD1 gene in the fat body of B. germanica peaked early in the day or subjective day under light-dark or constant dark conditions, whereas enzyme activity of cytosolic GSTs did not reflect the rhythmic pattern as well as BgGSTD1 expression. RNA interference (RNAi) was employed to study the function of BgGSTD1 in the circadian rhythm of permethrin susceptibility in B. germanica. Both BgGSTD1 mRNA level and cytosolic GSTs activity were significantly decreased by dsGSTD1 injection. In addition, survival of B. germanica with silenced BgGSTD1 was significantly decreased at night but not in the day when the cockroaches were exposed to permethrin. Total cytosolic GSTs activity demonstrated that is not the only gene involved in the circadian regulation of the permethrin resistance, although it is one of the major regulators of permethrin resistance. 

Circadian regulation of permethrin susceptibility by glutathione S-transferase (BgGSTD1) in the German cockroach (Blattella germanica).

C-Maf plays an important role in regulating cytokine production in TH cells. Its transactivation of IL-4 is optimized by phosphorylation at Tyr21, Tyr92, and Tyr131. However, the molecular mechanism regulating its tyrosine phosphorylation remains unknown. In this study, we demonstrate that Tec kinase family member Tec, but not Rlk or Itk, is a tyrosine kinase of c-Maf and that Tec enhances c-Maf-dependent IL-4 promoter activity. This effect of Tec is counteracted by Ptpn22, which physically interacts with and facilitates tyrosine dephosphorylation of c-Maf thereby attenuating its transcriptional activity. We further show that phosphorylation of Tyr21/92/131 of c-Maf is also critical for its recruitment to the IL-21 promoter and optimal production of this cytokine by TH17 cells. Thus, manipulating tyrosine phosphorylation of c-Maf through its kinases and phosphatases can have significant impact on TH cell-mediated immune responses. 

Reciprocal regulation of C-Maf tyrosine phosphorylation by Tec and Ptpn22.

In the past years, the concept of RNAi application for insect pest control has been proposed, considering the disruption of vital genes. However, the efficiency of RNAi is variable between different insect groups, especially by oral delivery of dsRNA. The purpose of this study is to assess the possibilities of RNAi as a tool for pest control using oral delivery of the dsRNAs encapsulated by liposome in the German cockroach Blattella germanica, which is highly sensitive to RNAi by injection of dsRNAs.

Yu-Hsien Lin

Department of Entomology

National Taiwan University

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