Induction of an inactivation pathway for ecdysteroids in larvae of the cotton leafworm, Spodoptera littoralis.
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ABSTRACT:
SUBMITTER: Chen JH
PROVIDER: S-EPMC1137147 | biostudies-other | 1994 Jul
REPOSITORIES: biostudies-other
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Project description:BackgroundThe cotton leafworm, Spodoptera littoralis, is a highly polyphagous pest of many cultivated plants and crops in Africa and Europe. The genome of this pest will help us to further understand the molecular mechanisms of polyphagy.ResultsHerein, the high-quality genome of S. littoralis was obtained by Pacific Bioscience (PacBio) sequencing. The assembled genome size of S. littoralis is 436.55 Mb with a scaffold N50 of 6.09 Mb, consisting of 17,207 annotated protein-coding genes. Phylogenetic analysis shows that S. littoralis and its sibling species S. litura diverged about 5.44 million years ago. Expanded gene families were mainly involved in metabolic detoxification and tolerance to toxic xenobiotics based on GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis. Comparative genomics analysis showed that gene families involved in detoxification and chemosensation were significantly expanded in S. littoralis, representing genetic characteristics related to polyphagy and an extensive host range.ConclusionsWe assembled and annotated the reference genome of S. littoralis, and revealed that this pest has the genetic features of strong detoxification capacity, consistent with it being a significant risk to a wide range of host crops. These data resources will provide support for risk assessment and early warning monitoring of major polyphagous agricultural pests.
| S-EPMC9080191 | biostudies-literature
Project description:The cotton leafworm, Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae), is one of the most devastating pests of crops worldwide. Several types of treatments have been used against this pest, but many of them failed because of the rapid development of genetic resistance in the different insect populations. G protein coupled receptors have vital functions in most organisms, including insects; thus, they are appealing targets for species-specific pest control strategies. Among the insect G protein coupled receptors, the diuretic hormone receptors have several key roles in development and metabolism, but their importance in vivo and their potential role as targets of novel pest control strategies are largely unexplored. With the goal of using DHR genes as targets to control S. littoralis, we cloned a corticotropin-releasing factor-like binding receptor in this species and expressed the corresponding dsRNA in tobacco plants to knock down the receptor activity in vivo through RNA interference. We also expressed the receptor in mammalian cells to study its signaling pathways. The results indicate that this diuretic hormone receptor gene has vital roles in S. littoralis and represents an excellent molecular target to protect agriculturally-important plants from this pest.
| S-EPMC4212857 | biostudies-literature
Project description:The gut microbiota is of crucial importance for the host with considerable metabolic activity. Although great efforts have been made toward characterizing microbial diversity, measuring components' metabolic activity surprisingly hasn't kept pace. Here we combined pyrosequencing of amplified 16S rRNA genes with in vivo stable isotope probing (Pyro-SIP) to unmask metabolically active bacteria in the gut of cotton leafworm (Spodoptera littoralis), a polyphagous insect herbivore that consumes large amounts of plant material in a short time, liberating abundant glucose in the alimentary canal as a most important carbon and energy source for both host and active gut bacteria. With (13)C glucose as the trophic link, Pyro-SIP revealed that a relatively simple but distinctive gut microbiota co-developed with the host, both metabolic activity and composition shifting throughout larval stages. Pantoea, Citrobacter and Clostridium were particularly active in early-instar, likely the core functional populations linked to nutritional upgrading. Enterococcus was the single predominant genus in the community, and it was essentially stable and metabolically active in the larval lifespan. Based on that Enterococci formed biofilm-like layers on the gut epithelium and that the isolated strains showed antimicrobial properties, Enterococcus may be able to establish a colonization resistance effect in the gut against potentially harmful microbes from outside. Not only does this establish the first in-depth inventory of the gut microbiota of a model organism from the mostly phytophagous Lepidoptera, but this pilot study shows that Pyro-SIP can rapidly gain insight into the gut microbiota's metabolic activity with high resolution and high precision.
| S-EPMC3903505 | biostudies-literature
Project description:The Egyptian cotton leafworm, Spodoptera littoralis is a highly invasive insect pest that causes extensive damage to many of the primary food crops. Considering the recent challenges facing global food production including climate change, knowledge about the invasive potential of this pest is essential. In this study, the maximum entropy model (MaxEnt) was used to predict the current global spatial distribution of the pest and the future distribution using two representative concentration pathways (RCPs) 2.6 and 8.5 in 2050 and 2070. High AUC and TSS values indicated model accuracy and high performance. Response curves showed that the optimal temperature for the S. littoralis is between 10 and 28 °C. The pest is currently found in Africa and is widely distributed across the Middle East and throughout Southern Europe. MaxEnt results revealed that the insect will shift towards Northern Europe and the Americas. Further, China was seen to have a suitable climate. We also extrapolated the impact of these results on major producing countries and how this affects trade flow, which help decision makers to take the invasiveness of such destructive pest into their account.
| S-EPMC10570271 | biostudies-literature
Project description:In the midgut cytosol of Lepidoptera, ecdysteroids undergo inactivation by transformation via the 3-dehydro derivative to the corresponding 3-epiecdysteroid (3 alpha-hydroxy) and by phosphate conjugation. The oxygen-dependent oxidase catalyses formation of 3-dehydroecdysteroid, which can be reduced either irreversibly by 3-dehydroecdysone 3 alpha-reductase to 3-epiecdysteroid, or by 3-dehydroecdysone 3 beta-reductase back to the initial ecdysteroid. Furthermore, these ecdysteroids undergo further inactivation by phosphorylation. These ecdysteroid transformations have been investigated in last instar larvae of the cotton leafworm, Spodoptera littoralis. The products of the phosphorylation have been characterized as predominantly ecdysteroid 2-phosphate accompanied by smaller amounts of the corresponding 22-phosphate. The phosphotransferases require Mg2+ and ATP. Whereas the 3-dehydroecdysone 3 alpha-reductase has a clear preference for NADPH rather than NADH, the corresponding 3 beta-reductase markedly favours NADH. The physiological significance of the latter enzyme is unclear. The profiles of the various enzymic activities in dialysed midgut cytosol supplemented with appropriate cofactors were determined throughout the last larval instar. All activities were detectable throughout the instar, but the respective enzymes exhibited maxima at different times. Ecdysone oxidase showed a peak early in the instar, with 3-dehydroecdysone 3 alpha-reductase increasing to a peak as the former activity declined. The 3-dehydroecdysone 3 beta-reductase exhibited peak activity late in the instar, a profile similar to that observed for the corresponding haemolymph enzyme involved in reduction of the 3-dehydroecdysone product of the prothoracic glands to ecdysone. Thus, the significance of the midgut 3 beta-reductase may be related to production of active hormone. Both ecydsteroid 22- and 2-phosphotransferases showed high activities early in the instar and then declined. The physiological significance of the profiles for the ecdysone oxidase, the 3-dehydroecdysone 3 alpha-reductase and phosphotransferases is unclear.
| S-EPMC1136299 | biostudies-other
Project description:BackgroundVarious proteins that display carbohydrate-binding activity in a Ca(2+)-dependent manner are classified into the C-type lectin family. They have one or two C-type carbohydrate-recognition domains (CRDs) composed of 110-130 amino acid residues in common. C-type lectins mediate cell adhesion, non-self recognition, and immuno-protection processes in immune responses and thus play significant roles in clearance of invaders, either as cell surface receptors for microbial carbohydrates or as soluble proteins existing in tissue fluids. The lectin of Spodoptera littoralis is still uncharacterized.MethodologyA single orf encoding a deduced polypeptide consisting of an 18-residue signal peptide and a 291-residue mature peptide, termed SpliLec, was isolated from the haemolymph of the cotton leafworm, S. littoralis, after bacterial challenge using RACE-PCR. Sequence analyses of the data revealed that SpliLec consists of two CRDs. Short-form CRD(1) and long-form CRD(2) are stabilized by two and three highly conserved disulfide bonds, respectively. SpliLec shares homology with some dipteran lectins suggesting possible common ancestor. The purified SpliLec exhibited a 140-kDa molecular mass with a subunit molecular mass of 35 kDa. The hemagglutination assays of the SpliLec confirmed a thermally stable, multisugar-binding C-type lectin that binds different erythrocytes. The purified SpliLec agglutinated microorganisms and exhibited comparable antimicrobial activity against gram (+) and gram (-) bacteria too.ConclusionsOur results suggested an important role of the SpliLec gene in cell adhesion and non-self recognition. It may cooperate with other AMPs in clearance of invaders of Spodoptera littoralis.
| S-EPMC3423437 | biostudies-literature
Project description:The emergence of pest resistance of Spodoptera littoralis (order; Lepidoptera, family; Noctuidae) towards the large scale of different classes of insecticides necessitates the development of some new poly-functionalized biphenyl and azabiphenyl with highly anticipated insecticidal bioresponse. Four new biphenyl carboxamidines 4a-d and four aza-analogue picolinamidine derivatives 8a-d were designed and prepared via the treatment of their corresponding carbonitriles with lithium-bis trimethylsilylamide [LiN(TMS)2], followed by hydrolysis with hydrogen chloride. Furthermore, these compounds were elucidated by spectral data, and their toxicity and insecticidal activity were screened against Spodoptera littoralis. Whereby, toxicological and biochemical aspects of the inventively synthesized biphenyl and azabiphenyl derivatives against the cotton leafworm, Spodoptera littoralis were inspected. As regards the indomitable LC50 and LC90 values, biphenyl and aza-analogues 8d, 8a, 4b, and 8b, revealed the furthermost forceful toxic effects with LC50 values of 113.860, 146.265, 216.624, and 289.879 ppm, respectively. Whereby, their LC90 values are 1235.108, 1679.044, 2656.296, and 3381.256 ppm, respectively, and toxicity index being 22.31%, 17.36%, 11.72%, and 8.76%, respectively, comparing with the already recommended, methomyl insecticide, lannate 90% SP (LC50, 25.396 and LC90, 57.860 and toxicity index, 100%). Additionally, electrochemical parameters via DFT studies were carried out for demonstrating and elucidation of structure-activity relationship (SAR) according to highly motived compounds, descriptors, and the in vivo insecticidal activities.
| S-EPMC10612163 | biostudies-literature
Project description:In this project we aim to share in increasing the production of the most important non-food agricultural product i.e. cotton via protection of it is plant. The usage of safe alternatives to the pesticides has become crucial due to several serious issues associated with the use of insecticides. Therefore, the families of new eco-friendly organic compounds that contain manly oxopropylthiourea scaffold will synthesis in their pure state by using green procedures. This compounds includes (i) poly functional substituted oxopropylthiourea, (ii) dihydroquinoline carboxylic acid, In second category, the structure of this compounds which may be related to the most famous insect growth regulators insecticides, will confirmed by elemental and modern spectroscopic analyses (such as IR, UV, 1HNMR and 13CNMR). In the final category, the synthesized compounds was checked toward the second & forth instar larvae of cotton leafworm, Spodoptera littoralis. The present data proved that values of LC50 of the most effected synthesized compound 8 was 2.412 ppm in which LC50 for commercial lufenuron was 2.295 ppm. Component 8 may be particularly effective due to the presence of fluorophenyl, cyanoacetamide, and carboxalic acid groups in their chemical makeup. In an additional effort to slightly improve insecticidal compounds, evaluation of the latent effects of the examined components on a number of biological parameters, such as adult longevity, pupal weight, proportion of normal, deformed pupae, & adult emergency, fecundity, & egg hatchability, was carried out.
| S-EPMC10421850 | biostudies-literature
Project description:BackgroundOdorant-Degrading Enzymes (ODEs) are supposed to be involved in the signal inactivation step within the olfactory sensilla of insects by quickly removing odorant molecules from the vicinity of the olfactory receptors. Only three ODEs have been both identified at the molecular level and functionally characterized: two were specialized in the degradation of pheromone compounds and the last one was shown to degrade a plant odorant.MethodologyPrevious work has shown that the antennae of the cotton leafworm Spodoptera littoralis, a worldwide pest of agricultural crops, express numerous candidate ODEs. We focused on an esterase overexpressed in males antennae, namely SlCXE7. We studied its expression patterns and tested its catalytic properties towards three odorants, i.e. the two female sex pheromone components and a green leaf volatile emitted by host plants.ConclusionSlCXE7 expression was concomitant during development with male responsiveness to odorants and during adult scotophase with the period of male most active sexual behaviour. Furthermore, SlCXE7 transcription could be induced by male exposure to the main pheromone component, suggesting a role of Pheromone-Degrading Enzyme. Interestingly, recombinant SlCXE7 was able to efficiently hydrolyze the pheromone compounds but also the plant volatile, with a higher affinity for the pheromone than for the plant compound. In male antennae, SlCXE7 expression was associated with both long and short sensilla, tuned to sex pheromones or plant odours, respectively. Our results thus suggested that a same ODE could have a dual function depending of it sensillar localisation. Within the pheromone-sensitive sensilla, SlCXE7 may play a role in pheromone signal termination and in reduction of odorant background noise, whereas it could be involved in plant odorant inactivation within the short sensilla.
| S-EPMC3246455 | biostudies-literature
Project description:The developmental changes in ecdysone 20-mono-oxygenase during the sixth larval instar of the cotton leafworm, Spodoptera littoralis, were investigated. The specific activity of mitochondrial ecdysone 20-mono-oxygenase in the fat-body exhibited a distinct peak at 72 h, at which time the larvae stop feeding. Immunoblot analyses, using antibodies raised against components of vertebrate mitochondrial steroidogenic enzyme systems [anti-(cytochrome P-450scc), anti-(cytochrome P-450(11) beta), anti-adrenodoxin and anti-(adrenodoxin reductase) antibodies], revealed the presence of specific immunoreactive polypeptides in fat-body mitochondrial extracts. In addition, these antibodies effectively inhibited fat-body mitochondrial ecdysone 20-mono-oxygenase activity. This suggests that the S. littoralis steroid-hydroxylating system(s) may contain polypeptide components analogous to those present in vertebrates. A close correlation between developmental changes in mitochondrial ecdysone 20-mono-oxygenase activity and the abundance of polypeptides (approx. 66 kDa and 50 kDa) recognized by the anti-(cytochrome P-450(11) beta) antibody and a polypeptide (approx. 52 kDa) recognized by the anti-(adrenodoxin reductase) antibody were observed in both fat-body and midgut. These results suggest that developmental changes in the abundance of components of the ecdysone 20-mono-oxygenase system may play an important role in the developmental regulation of the enzyme expression and, hence, of 20-hydroxyecdysone titre.
| S-EPMC1138078 | biostudies-other