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The German cockroach, Blattella germanica (L.), transmits a variety of pathogens and synthesizes nearly ten protein substances that trigger human allergies and asthma. With its strong fecundity and super resistance to various kinds of chemical pesticides, B. germanica is currently regarded as the most difficult to control global, household, insect pest. B. germanica uses sex pheromones for communication between the sexes. These pheromones are synthesized by sexually mature adult females. Their main function is to attract and stimulate male courtship and induce mating. Sex pheromone biosynthesis is therefore one of the core steps of sexual communication in this species. Articles on the regulation of sex pheromone synthesis in B. germanica have gradually increased in recent years, however, there has so far been no critical review summarizing progress and prospects for future research. This paper reviews important progress in research on contact sex pheromone biosynthesis and molecular regulation in B. germanica over the past three decades. It introduces researches on chemical composition and biosynthetic sites, focuses on the identification and characterization of key enzymatic genes involved in the sex pheromone biosynthesis pathway and the regulation of sex pheromone synthesis by the coordination between sex differentiation and juvenile hormone signaling. Prospects for future research are outlined with the aim of providing new theoretical support to develop new strategies for regulating cockroach behavior and new cockroach baits. [ABSTRACT FROM AUTHOR]

Water retention is critical for physiological homeostasis and survival in terrestrial insects. While deposition of hydrocarbons on insect cuticles as a key measure for water conservation has been extensively investigated, we know little about other mechanisms for preventing water loss in insects. Here, we report two fatty acid synthetic genes that are independent of hydrocarbon production but crucial for water retention in the German cockroach Blattella germanica (L.). First, an integument enriched fatty acid elongase gene (BgElo1) was identified as a critical gene for desiccation resistance in B. germanica; however, knockdown of BgElo1 surprisingly failed to cause a decline in cuticular lipids. In addition, RNA interference (RNAi)‐knockdown of an upstream fatty acid synthase gene (BgFas3) showed a similar phenotype, and transmission electron microscopy analysis revealed that BgFas3‐ or BgElo1‐RNAi did not affect cuticle architecture. Bodyweight loss test showed that repression of BgFas3 and BgElo1 significantly increased the weight loss rate, but the difference disappeared when the respiration was closed by freeze killing the cockroaches. A water immersion test was performed, and we found that BgFas3‐ and BgElo1‐RNAi made it difficult for cockroaches to recover from drowning, which was supported by the upregulation of hypoxia‐related genes after a 10‐h recovery from drowning. Moreover, a dyeing assay with water‐soluble Eosin Y showed that this was caused by the entry of water into the respiratory system. Our research suggests that BgFas3 and BgElo1 are required for both inward and outward waterproofing of the respiratory system. This study benefits the understanding of water retention mechanisms in insects. [ABSTRACT FROM AUTHOR]

Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle. Lipophorin loads and transports lipids, including hydrocarbons, from one tissue to another. In some insects, the lipophorin receptor (LpR), which binds to lipophorin and accepts its lipid cargo, is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes. However, it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown. We herein present the results of our molecular characterization, phylogenetic analysis, and functional annotation of the pea aphid (Acyrthosiphon pisum) LpR gene (ApLpR). This gene was transcribed throughout the A. pisum life cycle, but especially during the embryonic stage and in the abdominal cuticle. Furthermore, we optimized the RHA interference (RNAi) parameters by determining the ideal dose and duration for gene silencing in the pea aphid. We observed that the RNAi‐based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity. Additionally, a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress, with decreased survival rates under simulated drought conditions. Moreover, ApLpR expression levels significantly increased in response to the desiccation treatment. These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress. Furthermore, this gene is vital for aphid reproduction. Therefore, the ApLpR gene of A. pisum may be a novel RNAi target relevant for insect pest management. [ABSTRACT FROM AUTHOR]

BACKGROUND The use of trap crops can reduce the egg production of female Plutella xylostella in cruciferous vegetables and is an effective method for controlling this pest. To date, most of the trap plants that have been studied are cruciferous plants containing high concentrations of glucosinolates, which are more attractive to P. xylostella female adults. However, the application of these trap plants also has some limitations. Studies have shown that aqueous extracts of cruciferous plants can attract P. xylostella to lay eggs. In this study, we utilized the extract of Chinese kale to treat a non‐host plant, the faba bean, and evaluated the possibility of using it as a dead‐end trap plant for P. xylostella control. RESULTS: Plutella xylostella females laid significantly more eggs on faba beans that had been sprayed with the extract of Chinese kale rather than on Chinese kale itself. The first instar larvae of P. xylostella failed to survive on faba beans. Notably, the faba beans with the Chinese kale extract had the strongest attraction effect on P. xylostella females when placed 3 m away from the Chinese kale. Moreover, this attraction effect of faba beans on P. xylostella for oviposition lasted for up to 15 days. CONCLUSION: Faba bean plants sprayed with the aqueous extract of Chinese kale represent a potential dead‐end trap plant for P. xylostella adults and their oviposition while being invariably deadly for their offspring. The present study provides a new proof of concept of using a non‐cruciferous trap plant for P. xylostella management. [ABSTRACT FROM AUTHOR]

A Si-capped Ge quantum dot sample was self-assembly grown via Stranski-Krastanov mode in a molecular beam epitaxy system with the Si capping layer deposited at 300 °C. After annealing the sample in an oxygen atmosphere at 1000 °C, a structure, namely two layers of quantum dots, was formed with the newly formed Ge-rich quantum dots embedded in the oxidized matrix with the position accurately located upon the as-grown quantum dots. It has been found that the formation of such nanostructures strongly depends upon the growth temperature and oxygen atmosphere. A growth mechanism was proposed to explain the formation of the nanostructure based on the Ge diffusion from the as-grown quantum dots, Ge segregation from the growing oxide, and subsequent migration/agglomeration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cuticle penetration plays an important role as a mechanism of insecticide resistance, but the underlying molecular mechanism remains poorly understood. In Blattella germanica, the cytochrome P450 gene, CYP4G19, is overexpressed in a pyrethroid‐resistant strain. Here, we investigated whether CYP4G19 is involved in the biosynthesis of hydrocarbons and further contributes to cuticular penetration resistance in B. germanica. RESULTS: Compared with the susceptible strain, pyrethroid‐resistant cockroaches showed lower cuticular permeability with Eosin Y staining. Removal of epicuticular lipids, mainly nonpolar hydrocarbons, with a hexane wash intensified the cuticular permeability and decreased the resistance index of the resistant strain. CYP4G19 was predominately expressed in the abdominal integument and could be upregulated by desiccation stress or short exposure to beta‐cypermethrin. Overexpression of CYP4G19 in the resistant strain was positively correlated with a higher level of cuticular hydrocarbons (CHCs). RNAi‐mediated knockdown of CYP4G19 significantly decreased its expression and caused a reduction in CHCs. Meanwhile, CYP4G19 suppression resulted in a non‐uniform array of the lipid layer, enhanced cuticle permeability, and compromised insecticide tolerance. CONCLUSION: Our findings confirm that CYP4G19 is involved in hydrocarbon production and appears to contribute to hydrocarbon‐based penetration resistance in B. germanica. This study highlights the lipid‐based penetration resistance, advancing our understanding of the molecular mechanism underlying P450‐mediated cuticular penetration resistance in insects. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Hyperlipidemia has been shown to stimulate vascular smooth muscle cell (VSMC) proliferation. Wnt signaling pathway plays a critical role in embryonic development and cell proliferation. In this study, Sprague-Dawley rats fed with high-fat or normal diet for 12 weeks were sacrificed, and the thoracic aorta was harvested to determine wnt3a, β-catenin, T-cell factor 4 (TCF4), and cyclin D1 expressions. VSMC proliferation within thoracic aorta and lipid accumulation within VSMCs were detected. Rat aortic VSMCs were cultured in serum from rats with hyperlipidemia or DKK-1; Wnt3a, β-catenin, TCF4, and cyclin D1 expressions, and cell cycle distribution were determined. The findings demonstrated that increased number of VSMCs, lipid droplets, and vacuoles within thoracic aorta in the high-fat-fed group. Compared with controls, VSMCs from high-fat-fed rats showed higher mRNA expressions of wnt3a, β-catenin, TCF4, and cyclin D1, as well as in VSMCs cultured with hyperlipidemic serum. After 24 h, VSMCs stimulated with hyperlipidemic serum showed significantly increased cell number and S-phase entry compared with cells exposed to normolipidemic serum. These effects were blocked by DKK-1. These results suggest that Wnt/β-catenin signaling plays an important role in hyperlipidemia-induced VSMC proliferation. [ABSTRACT FROM AUTHOR]

A multilayer film (multi-film), consisting of alternate Er-Si-codoped Al2O3 (ESA) and Si-doped Al2O3 (SA) sublayers, is synthesized by co-sputtering from separated Er, Si, and Al2O3 targets. The dependence of Er3+ related photoluminescence (PL) properties on annealing temperatures over 700-1100 °C is studied. The maximum intensity of Er3+ photoluminance (PL), about 10 times higher than that of the monolayer film, is obtained from the multi-film annealed at 950 °C. The enhancement of Er3+ PL intensity is attributed to the energy transfer from the silicon nanocrystals (Si-NCs) to the neighboring Er3+ ions. The effective characteristic interaction distance (or the critical ET length) between Er and carriers (Si-NCs) is ∼3 nm. The PL intensity exhibits a nonmonotonic temperature dependence. Meanwhile, the PL integrated intensity at room temperature is about 30% higher than that at 14 K. [ABSTRACT FROM AUTHOR]