siRNA enrichment in Argonaute 2-depleted Blattella germanica

The therapeutic prospects of N-acetylgalactosamine-siRNA conjugates

RNA interference has become increasingly used for genetic therapy following the rapid development of oligonucleotide drugs. Significant progress has been made in its delivery system and implementation in the treatment of target organs. After a brief introduction of RNA interference technology and siRNA, the efficiency and stability of GalNAc-siRNA conjugates are highlighted since several oligonucleotide drugs of GalNAc have been approved for clinical use in recent years. The structure and features of GalNAc-siRNA conjugates are studied and the clinical efficiency and limitations of oligonucleotide-based drugs are summarized and investigated. Furthermore, another delivery system, lipid nanoparticles, that confer many advantages, is concluded, includ-ing stability and mass production, compared with GalNAc-siRNA conjugates. Importantly, developing new approaches for the use of oligonucleotide drugs brings hope to genetic therapy.

RNAi-based pest control: Production, application and the fate of dsRNA

The limitations of conventional pesticides have raised the demand for innovative and sustainable solutions for plant protection. RNA Interference (RNAi) triggered by dsRNA has evolved as a promising strategy to control insects in a species-specific manner. In this context, we review the methods for mass production of dsRNA, the approaches of exogenous application of dsRNA in the field, and the fate of dsRNA after application. Additionally, we describe the opportunities and challenges of using nanoparticles as dsRNA carriers to control insects. Furthermore, we provide future directions to improve pest management efficiency by utilizing the synergistic effects of multiple target genes. Meanwhile, the establishment of a standardized framework for assessment and regulatory consensus is critical to the commercialization of RNA pesticides.

Identification and functional characterization of the German cockroach, Blattella germanica, short interspersed nuclear elements

In recent decades, experimental data has accumulated indicating that short interspersed nuclear elements (SINEs) can play a significant functional role in the regulation of gene expression in the host genome. In addition, molecular markers based on SINE insertion polymorphisms have been developed and are widely used for genetic differentiation of populations of eukaryotic organisms. Using routine bioinformatics analysis and publicly available genomic DNA and small RNA-seq data, we first described nine SINEs in the genome of the German cockroach, Blattella germanica. All described SINEs have tRNA promoters, and the start of their transcription begins 11 bp upstream of an “A” box of these promoters. The number of copies of the described SINEs in the B. germanica genome ranges from several copies to more than a thousand copies in a SINE-specific manner. Some of the described SINEs and their degenerate copies can be localized both in the introns of genes and loci known as piRNA clusters. piRNAs originating from piRNA clusters are shown to be mapped to seven of the nine types of SINEs described, including copies of SINEs localized in gene introns. We speculate that SINEs, localized in the introns of certain genes, may regulate the level of expression of these genes by a PIWI-related molecular mechanism.

Regulation of insulin-like peptide expression in adult Blattella germanica females

The insulin-IGF-signalling (IIS) pathway regulates key processes in metazoans. The pathway is activated through the binding of the ligands, which in insects are usually referred to as insulin-like peptides (ILPs), to a class of receptor tyrosine kinases, the insect insulin receptor. To study the pathway regulation, it is therefore essential to understand how ILPs are produced and released. In this study we analysed the factors that regulate the expression of the seven ILPs (BgILPs) expressed in adult females of the German cockroach, Blattella germanica. The results showed that the starvation-induced expression reduction of brain BgILP3, 5 and 6 and fat body BgILP7 is not due to reduced juvenile hormone (JH) or decreased TOR pathway activity. In addition, depletion of FoxO in starved females did not correct the low levels of these BgILPs, but even reduced further BgILP5 expression, indicating the need to maintain certain basal levels of BgILP5 even during starvation. Furthermore, JH promoted increased BgILP5 and decreased BgILP3 expression in the brain, an effect that required Methoprene-tolerant (Met), the JH receptor, but not Krüppel homolog 1 (Kr-h1), the main JH transducer. On the other hand, JH inhibited the expression of BgILP7 in the fat body, although in this case, the action required both Met and Kr-h1. In addition, JH reduction treatments produced a decrease in the expression of the insulin receptor in the fat body, which suggests an increase in IIS. The results show a peculiar regulation of ILP expression in adult B. germanica females, which is clearly different than that seen in other species. This is understandable given that gene duplications in recent clades have resulted in different sets of ILP genes, involving substantial changes in gene regulatory networks.