cadherin insect

The Asian citrus psyllid, Diaphorina citri, is the vector of Candidatus Liberibacter asiaticus (CLas), the presumed causative agent of citrus greening disease. For successful transmission, CLas must cross the gut barrier, requiring interaction with proteins on the midgut epithelium. We compared the relative abundance of gut surface proteins for both adult and nymph D. citri, as nymphs are particularly susceptible to CLas infection. To enrich for gut surface proteins, brush border membrane vesicles were prepared from dissected guts, and proteins identified from triplicate samples run on a timsTOF mass spectrometer...

Use of edible insects as an alternative source of proteins in food and feed is increasing. These last years, numerous companies in Europe have started producing insects for food and feed purposes. In the European Union, the use of edible insects for human consumption falls within Regulation (EU) No. 2015/2283 on novel foods. For feed, Commission Regulation (EU) 2017/893 authorizes seven insect species as processed animal proteins for aquaculture. Methods of authentication are required to check the conformity of the products...

One approach to control dengue virus transmission is the symbiont Wolbachia, which limits viral infection in mosquitoes. Despite plans for its widespread use in Aedes aegypti, Wolbachia's mode of action remains poorly understood. Many studies suggest that the mechanism is likely multifaceted, involving aspects of immunity, cellular stress and nutritional competition. A previous study from our group used artificial selection to identify a new mosquito candidate gene related to viral blocking; alpha-mannosidase-2a (alpha-Mann-2a) with a predicted role in protein glycosylation...

Multiple insect pest species have developed field resistance to Bt-transgenic crops. There has been a significant amount of research on protein-coding genes that contribute to resistance, such as the up-regulation of protease activity or altered receptors. However, our understanding of the role of non-protein-coding mechanisms in Bt-resistance is minimal, as is also the case for resistance to chemical pesticides. To address this problem relative to Bt, RNA-seq was used to examine statistically significant, differential gene expression between a Cry1Ac-resistant (~100-fold resistant) and Cry1Ac-susceptible strain of Helicoverpa zea , a prevalent caterpillar pest in the USA...

Transgenic crops producing Bacillus thuringiensis (Bt) toxins are widely planted for insect control, but their efficacy may decrease as insects evolve resistance. Understanding the genetic basis of insect resistance is essential for developing an integrated strategy of resistance management. To understand the genetic basis of resistance in pink bollworm ( Pectinophora gossypiella ) to Bt cotton in the Yangtze River Valley of China, we conducted an F2 screening for alleles associated with resistance to the Bt (Cry1Ac) protein for the first time...

The large-scale commercial cultivation of genetically modified (GM) cotton has brought significant economic and environmental benefits. However, GM crops must undergo strict environmental monitoring and long-term observation. An important natural enemy insect in cotton fields, Geocoris pallidipennis, can ingest the Bt protein expressed in GM cotton by feeding on herbivorous insects that feed on the cotton. However, the potential risk of GM cotton to G. pallidipennis is still unclear. We here evaluated the effects of Bt cotton expressing the Cry1Ac/1Ab protein on nymphs and adults G...

The diamondback moth, Plutella xylostella , is a lepidopteran insect that mainly harms cruciferous vegetables, with strong resistance to a variety of agrochemicals, including Bacillus thuringiensis (Bt) toxins. This study intended to screen genes associated with Bt resistance in P. xylostella by comparing the midgut transcriptome of Cry1Ac-susceptible and -resistant strains together with two toxin-treated strains 24 h before sampling. A total of 12 samples were analyzed by BGISEQ-500, and each sample obtained an average of 6...

Photorhabdus bacteria secrete a repertoire of protein toxins that can kill the host insect. Among them, toxin complex (Tc) proteins have gained significant attention due to their wider conservation across the different bacterial genera. In our laboratory, a C-terminal domain of TcaB protein was characterized from P. akhurstii bacterium that conferred the potent oral insecticidal effect on Galleria mellonella . However, the role of insect gut receptors in the TcaB intoxication process was yet to be investigated...

Insect midgut cadherins function as receptors and play critical roles as protein receptors of insecticidal Bacillus thuringiensis (Bt) toxins used as biopesticides and in Bt transgenic crops worldwide. Here, we cloned and characterized the full-length midgut cadherin (CmCad) cDNA from the rice leaffolder (Cnaphalocrocis medinalis), a destructive pest of rice in many Asian countries. Expression of recombinant proteins corresponding to the extracellular domain of CmCad allowed testing binding of Cry proteins...

Transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal proteins have been extensively planted for insect pest control, but the evolution of Bt resistance in target pests threatens the sustainability of this approach. Mutations of cadherin in the midgut brush border membrane was associated with Cry1Ac resistance in several lepidoptera species, including the Asian corn borer, Ostrinia furnacalis , a major pest of maize in Asian-Western Pacific countries. However, the causality of O. furnacalis cadherin ( OfCad ) with Cry1Ac resistance remains to be clarified...

Field-evolved resistance of insect pests to Bacillus thuringiensis (Bt) toxins (Cry toxins) is a threat to the efficacy of Bt-based bio-insecticides and transgenic crops. Recent reports have suggested that ATP-binding cassette transporter subfamily C2 (ABCC2) and cadherin-like receptor play important roles in conferring susceptibility to Cry1 toxins. However, the receptors involved in Bt susceptibility in each insect remain unclear. To determine the receptors that are involved in the susceptibility of Bombyx mori to Cry1 toxins (1Ab, 1Ac and 1Fa), we conducted diet overlay bioassay using B...

Cadherin, aminopeptidase N (APN) and alkaline phosphatase (ALP) have been characterized as Cry receptors. In this study, comparative genomic analysis of the 3 receptor families was performed in 7 insects. ALPs and APNs are divided into 3 and 8 clades in phylogenetic trees, respectively. ALPs in clade 3 and APNs in clade 1 contain multiple paralogs within each species and most paralogs are located closely in chromosomes. Drosophila melanogaster has expanded APNs in clade 5 and were lowly expressed in midgut...

Resistance evolution of target pests reduces efficacy of Bacillus thuringiensis Cry toxins used in insect-pest control. Mutations in Cadherin (CAD) or ATP-binding cassette (ABC) transporters genes are linked to Cry resistance in different pests. Also, it has been shown that ABCC2 and CAD have synergistic interaction on Cry toxicity when co-express in cell lines, which we confirmed here by Helicoverpa armigera HaABCC2 and HaCAD expression in Hi5 cells. To confirm that CAD and ABC transporters interact in vivo, we constructed nearly H...

The Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), is a major pest of potato plants worldwide and is notorious for its ability to develop resistance to insecticides. Cry3 toxins synthesized by Bacillus thuringiensis ssp. tenebrionis have been used successfully to manage this pest. Resistance to Cry toxins is a concerning problem for many insect pests; therefore, it is important to determine the mechanisms by which insects acquire resistance to these toxins. Cadherin-like and ABC transporter proteins have been implicated in the mode of action of Cry toxins as mutations in these genes render lepidopterans resistant to them; however, clear consensus does not exist on whether these proteins also play a role in Cry3 toxin activity and/or development of resistance in coleopterans...

Soybean looper (SBL), Chrysodeixis includens (Walker), is one of the major lepidopteran pests of soybean in the American continent. SBL control relies mostly on the use of insecticides and genetically modified crops expressing Bacillus thuringiensis (Bt) insecticidal Cry proteins. Due to the high selection pressure exerted by these control measures, resistance has developed to different insecticides and Bt proteins. Nevertheless, studies on the mechanistic background are still scarce. Here, the susceptibility of the laboratory SBL-Benzon strain to the Bt proteins Cry1Ac and Cry1F was determined in diet overlay assays and revealed a greater activity of Cry1Ac than Cry1F, thus confirming results obtained for other sensitive SBL strains...

In this article, we review the latest works on the insecticidal mechanisms of Bacillus thuringiensis Cry toxins and the resistance mechanisms of insects against Cry toxins. Currently, there are two models of insecticidal mechanisms for Cry toxins, namely, the sequential binding model and the signaling pathway model. In the sequential binding model, Cry toxins are activated to bind to their cognate receptors in the mid-intestinal epithelial cell membrane, such as the glycophosphatidylinositol (GPI)-anchored aminopeptidases-N (APNs), alkaline phosphatases (ALPs), cadherins, and ABC transporters, to form pores that elicit cell lysis, while in the signaling pathway model, the activated Cry toxins first bind to the cadherin receptor, triggering an extensive cell signaling cascade to induce cell apoptosis...

Bacillus thuringiensis (Bt) bacteria produce Cry toxins that kill insect pests. Insect specificity of Cry toxins relies on their binding to larval gut membrane proteins such as cadherin and ATP-binding cassette (ABC) transporter proteins. Mutations in ABC transporters have been implicated in high levels of resistance to Cry toxins in multiple pests. Spodoptera frugiperda is an insect pest susceptible to Cry1Fa and Cry1Ab toxins while Mythimna separata is tolerant to Cry1Fa and less susceptible to Cry1Ab. Here, we analyzed the potential role of ABCC2 in determining the susceptibility of S...

The trachea of insects is a tubular epithelia tissue that transports oxygen and other gases. It serves as a useful model for the studying of the cellular and molecular events involved in epithelial tube formation. Almost all of the extracellular matrix can be degraded by Matrix metalloproteinases (MMPs), which is closely related to the processes of development and regeneration. The regulation of trachea by MMPs is roughly known in previous studies, but the detailed regulation mechanism and involved gene function are not fully explored...

Helicoverpa armigera is a major insect pest of several crops worldwide. This insect is susceptible to some Bacillus thuringiensis (Bt) Cry insecticidal proteins expressed in transgenic crops or used in biopesticides. Previously, we identified H. armigera prohibitin (HaPHB) as a Cry1Ac-binding protein. Here, we further analyzed the potential role of PHB as a Cry toxin receptor in comparison to cadherin (CAD), well recognized as a Cry1Ac receptor. HaPHB-2 midgut protein and HaCAD toxin-binding region (TBR) fragment from H...

Evolution of resistance by pests reduces the benefits of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Here we analyzed resistance to Bt toxin Cry1Ac in a field-derived strain of pink bollworm (Pectinophora gossypiella), a global pest of cotton. We discovered that the r14 allele of the pink bollworm cadherin gene (PgCad1) has a 234-bp insertion in exon 12 encoding a mutant PgCad1 protein that lacks 36 amino acids in cadherin repeat 5 (CR5). A strain homozygous for this allele had 237-fold resistance to Cry1Ac, 1...