RNA interference (RNAi) has become a widely used loss-of-function tool in eukaryotes; however, the delivery of double-stranded (ds)RNA) to the target cells remains a major challenge when exploiting the RNAi-technology. In insects, the efficiency of RNAi is highly species-dependent. Yet, the mechanism of cell entry in insects has only been characterized in a cell line of the fruit fly, Drosophila melanogaster, a species that is well known to be poorly amenable to environmental RNAi. In the present paper, we demonstrate that silencing vacuolar H-ATPase 16 (vha16) and clathrin heavy chain (clath), two components of the Clathrin-dependent endocytosis pathway, together with pharmacological inhibition of scavenger receptors with polyinosine and dextran sulphate, can significantly attenuate the highly robust RNAi response in the desert locust, Schistocerca gregaria.

A protein displaying significant similarity to mammalian HMGA (high-mobility group A) proteins, but also bearing unique structural features, was isolated from silkmoth (Bombyx mori) follicular cells. This factor, named BmHMGA, exhibits specific binding preference for chorion gene promoter elements and induces DNA bending thereon. BmHMGA deploys temporal-specific interaction with transcription factors BmC/EBP (C/EBP is CCAAT/enhancer-binding protein) and BmGATAβ during follicle maturation. The respective protein complexes can be detected on chorion gene promoters in vivo, with different developmental profiles each time. Analogous interaction takes place on the putative promoter of the BmC/EBP gene, hinting towards a transcriptional circuit that is responsible for the progress of choriogenesis as a whole. Finally, transient suppression of BmHMGA expression led to down-regulation of chorion genes and the BmC/EBP gene, and revealed recruitment of BmC/EBP, BmGATAβ and TFIID (transcription factor IID)/TBP (TATA-box-binding protein) by BmHMGA. A revised model for chorion gene regulation is discussed in view of these findings.

A recombinant plasmid vector was constructed in which the bacterial LacZ gene was placed under the control of a Bombyx mori baculovirus early promoter. The vector proved to be active in transfected cultured dipteran and lepidopteran cells. Co-transfection carried out with this recombinant plasmid vector and a plasmid containing the hygromycin phosphotransferase gene followed by selection with the antibiotic hygromycin B, resulted in stable transformation of cultured Drosophila melanogaster Schneider 2 cells. Southern blot analysis of the host cell's genomic DNA in combination with chromosomal in situ hybridization demonstrated that multiple copies of both plasmids were integrated in the host cell's genome.

Farming of edible insects has been proposed as a means to reduce current practices of harvesting from the wild. While farming could relieve the pressure on wild populations, as well as on their natural habitats, and generate a continuous supply of edible insects to the consumers, the high cost of commercial chicken feeds is still a challenge to many farmers. The aim of this study was to investigate whether the partial replacement of commercial chicken feed with the farm weed, wandering Jew (Commelina sinensis), would have an impact on weight gain and microbial quality of farmed field crickets (Gryllus bimaculatus). Therefore, we have experimentally compared two types of feed: (1) starter commercial chicken feed only (SO); and (2) starter commercial chicken feed supplemented with fresh wandering Jew weeds (S+W). After a feeding period of thirty days, the final body weight differed significantly (P=0.026) between crickets fed with SO and with S+W, which averaged at 1.11 and 1.39 g, respectively. Generally, high counts of total aerobic, Enterobacteriaceae, lactic acid bacteria, bacterial endospores, yeasts and moulds were observed in both experimental groups. However, bacterial endospore counts of S+W fed crickets (2.7 log cfu/g) were significantly lower (P=0.021) than these of the SO fed ones (3.9 log cfu/g). Metagenetic analyses indicated that Proteobacteria, Firmicutes and Tenericutes were the most abundant phyla, while members of the family Coxiellacea, and the genera Lactobacillus, and Spiroplasma were the most abundant operational taxonomic units (OTUs). Concerning the food safety, a few OTUs could be associated with potential food pathogens, such as Clostridiaceae, Staphylococcus and Enterobacteriaceae. In summary, the inclusion of fresh wandering Jew weeds in commercial starter chicken feed produced crickets with increased body weight and improved microbial quality.

Inducible, vector-based, expression systems that allow fine control of transgene expression are gaining more and more use in fundamental research as well as in therapeutic applications. In an effort to develop a tightly regulated heterologous expression system for Drosophila Schneider 2 cells, three different inducible reporter constructs were compared. These comprised six copies of the glucocorticoid response element fused to one of three distinct types of Drosophila gene promoters: (1) a TATA-box containing, (2) a TATA-less and (3) a bidirectional core sequence. These were fused to a luciferase reporter gene. The promoter constructs displayed different basal as well as agonist-induced activities. The implications of the observations made are discussed in the context of promoter properties and of induction of genes that may be studied in Drosophila.