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PubMed2005

Two different Bacillus thuringiensis toxin genes confer resistance to beet armyworm (Spodoptera exigua Hübner) in transgenic Bt-shallots (Allium cepa L.).

Agrobacterium-mediated genetic transformation was applied to produce beet armyworm (Spodoptera exigua Hübner) resistant tropical shallots (Allium cepa L. group Aggregatum). A cry1Ca or a H04 hybrid gene from Bacillus thuringiensis, driven by the chrysanthemum ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (Rubisco SSU) promoter, along with the hygromycin phosphotransferase gene (hpt) driven by the CaMV 35S promoter, was employed for genetic transformation. An average transformation frequency of 3.68% was obtained from two shallot cultivars, Tropix and Kuning. After transfer of the in vitro plants to the greenhouse 69% of the cry1Ca and 39% of the H04 transgenic shallots survived the first half year. After one year of cultivation in the greenhouse the remaining cry1Ca and H04 transgenic plants grew vigorously and had a normal bulb formation, although the cry1Ca transgenic plants (and controls) had darker green leaves compared to their H04 counterparts. Standard PCR, adaptor ligation PCR and Southern analyses confirmed the integration of T-DNA into the shallot genome. Northern blot and ELISA analyses revealed expression of the cry1Ca or H04 gene in the transgenic plants. The amount of Cry1Ca expressed in transgenic plants was higher than the expression levels of H04 (0.39 vs. 0.16% of the total soluble leaf proteins, respectively). There was a good correlation between protein expression and beet armyworm resistance. Cry1Ca or H04 gene expression of at least 0.22 or 0.08% of the total soluble protein in shallot leaves was sufficient to give a complete resistance against beet armyworm. This confirms earlier observations that the H04 toxin is more toxic to S. exigua than the Cry1Ca toxin. The results from this study suggest that the cry1Ca and H04 transgenic shallots developed could be used for introducing resistance to beet armyworm in (sub) tropical shallot.

Animals↗
PubMed2005

Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae).

Recent studies have shown that transgenic insect resistant plants can have negative effects on non-target herbivores as well as on beneficial insects. The study of tritrophic interactions gives insight into the complex mechanisms of food webs in the field and can easily be incorporated into a tiered risk assessment framework. We investigated the effects of transgenic maize (Zea mays) expressing insecticidal proteins derived from Bacillus thuringiensis (Bt maize) on Spodoptera littoralis, a non-target herbivore, and on the hymenopteran parasitoid Cotesia marginiventris. In a laboratory study, S. littoralis larvae were reared for their whole lifespan on a mixture of leaves and stems from 2-4-week old Bt maize plants. S. littoralis survival, developmental times and larval weights were significantly affected by Bt maize diet. However, adult moths, which survived development on Bt maize, were the same size as the adults from the control group. C. marginiventris survival, developmental times and cocoon weights were significantly negatively affected if their S. littoralis host larva had been fed Bt maize. ELISA tests confirmed that S. littoralis larvae ingest high amounts of CrylA(b) toxin while feeding on Bt maize. In S. littoralis pupae and in C. marginiventris cocoon silk, only traces of the toxin could be detected. No toxin was found in S. littoralis and C. marginiventris adults. Thus the toxin is not accumulating in the trophic levels and in fact appears to be excreted. Our results suggest that the effects on C. marginiventris when developing in susceptible S. littoralis larvae are indirect (host mediated). The biological relevance of those results and the significance of this study in risk assessment are discussed.

Animals↗
PubMed2005

Characterization of p24 gene of Spodoptera litura multicapsid nucleopolyhedrovirus.

Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) p24 gene is 753 bp long, potentially encoding 244 amino acids with a predicted molecular weight of 27.3 kDa. Homology analysis indicated that SpltMNPV P24 has 20-36% amino acid identity with that of other known baculoviruses. RT-PCR results showed that the p24 gene is transcribed actively at the late stage of infection and the mRNA start site was mapped within a consensus baculovirus late promoter sequence (ATAAG). Western blot analysis of extracts from SpltMNPV-infected S. litura cells detected a specific 28 kDa protein, and this protein was not N-glycosylated. Structural localization revealed that SpltMNPV P24 was associated with the nucleocapsid of occlusion-derived virus (ODV) as a complex form of 83 kDa.

Amino Acid Sequence↗
PubMed2006

Identification of Spodoptera litura multicapsid nucleopolyhedrovirus ORF97, a novel protein associated with envelope of occlusion-derived virus.

Open reading frame (ORF) 97 of Spodoptera litura multicapsid nucleopolyhedrovirus (Splt97) is a member of 11k gene family (InterPro database accession number: IPR009313) in insect viruses, potentially encoding 112 amino acids with a predicted molecular weight of 13.2 kDa. Sequence analysis indicated that Splt97 has 8-50% amino acid identity with the homologues of other known baculoviruses including Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) ORF108. Splt97 transcription in SpltMNPV-infected Spli-221 cells was detected from 6 to 96 h postinfection (p.i.) and the mRNA start site was mapped within a consensus baculovirus early promoter motif (ACATT). Time course of Splt97 expression in SpltMNPV-infected cells showed that Splt97 was expressed from 48 through 96 h p.i. as a 13 kDa protein. Western blot analysis revealed that Splt97 was present in occlusion-derived virus (ODV). Furthermore, when ODV was fractionated into nucleocapsid and envelope components, Splt97 was shown to be present only in the envelope. These results suggested that Splt97 was a baculovirus ODV-associated protein.

Amino Acid Sequence↗
PubMed2003

Synthesis of fluorinated analogs of myristic acid as potential inhibitors of Egyptian armyworm (Spodoptera littoralis) delta11 desaturase.

To study the activity of the different desaturases present in the pheromone biosynthetic pathway of the Egyptian armyworm, Spodoptera littoralis, we prepared a series of mono- and gem-difluorinated analogs of myristic acid with halogen substitution at the C8-C11 positions of the aliphatic chain via specifically positioned dithiane precursors. Thus, transformation of dithianes by treatment with N-bromosuccinimide in the presence of H2O followed by reduction with LiAlH4 afforded the appropriate alcohols, which reacted with diethylaminosulfur trifluoride to give rise to the corresponding monofluoroderivative intermediates. Alternatively, the introduction of the gem-difluoro functionality was carried out by reaction of the appropriate dithiane intermediate with 1,3-dibromo-5,5-dimethylhydantoin in the presence of HF/pyridine. The activity of these fluorinated FA as substrates and inhibitors of the desaturases involved in the biosynthesis of the sex pheromonal blend of S. littoralis has been studied. In this case, 11-fluorotetradecanoic acid elicited a moderate inhibitory activity of delta11 desaturase.

Animals↗
PubMed1997

Possible fatty acyl pheromone precursors in Spodoptera littoralis. Search for 11- and 12-hydroxytetradecanoic acids in the pheromone gland.

Lipid extracts of Spodoptera littoralis pheromone glands submitted to acid methanolysis using: (i) sulfuric acid/methanol/benzene (0.1:4:2, by vol) at 90 degrees C for 1 h; (ii) 12 N HCI/methanol (1:2, vol/vol) at 90 degrees C for 1 h, or (iii) 14% BF3-MeOH at 90 degrees C for 1 h did not reveal the presence of either 11- or 12-hydroxytetradecanoic acid in the extracts, as concluded from the gas chromatography-mass spectrometry analyses. Under the above methanolysis conditions, a synthetic sample of methyl (14, 14, 14-2H3) 12-hydroxytetradecanoate remained unaltered. These results may indicate that formation of (E)-11-tetradecenoic acid from tetradecanoic acid does not occur in the pheromone gland by dehydration of an intermediate hydroxyacid. Acid methanolysis of a lipidic extract using BF3-MeOH led to the formation of a mixture of methoxy fatty acid methyl esters, identified by gas chromatography-mass spectrometry. These methoxy derivatives should arise from BF3-catalyzed addition of methanol to the double bond of the natural monounsaturated fatty acyl derivatives present in the gland. Thus, under the same conditions, a synthetic sample of methyl (Z)-11-tetradecenoate was partially transformed into methyl 11-methoxytetradecanoate and methyl 12-methoxytetradecanoate. This reaction might be a useful alternative procedure to obtain methoxy derivatives of olefins, which are very helpful for the structural characterization of the parent alkenes.

Animals↗
PubMed1994

A comparison and analysis of the toxicity and receptor binding properties of Bacillus thuringiensis CryIC delta-endotoxin on Spodoptera littoralis and Bombyx mori.

The binding of L-[35S]methionine in vivo labelled CryIC toxin to its receptor in brush border membrane vesicle (BBMV's) prepared from Spodoptera littoralis and Bombyx mori was studied. Both insect species were highly susceptible to the CryIC toxin in bioassays, B. mori being 7-fold more sensitive to CryIC than S. littoralis (LC50's of 10 ng/cm2 and 70 ng/cm2, respectively). Competition and direct binding experiments revealed saturable high-affinity binding sites on BBMV's from both insects which had similar binding characteristics for the CryIC toxin (Kd = 10 nM, Bmax = 8 to 9 pmol/mg BBMV's and IC50 = 37 nM for both inspect species). Thus a specific receptor for the CryIC toxin is present in both insect species and the 7-fold greater potency of CryIC towards B. mori is not due to qualitative or quantitative differences in binding affinity or receptor site concentration. Dissociation experiments also indicated that the binding of [35S]CryIC to B. mori BBMV's is partially reversible.

Animals↗
PubMed1995

Delta-endotoxins induce cation channels in Spodoptera frugiperda brush border membranes in suspension and in planar lipid bilayers.

Membrane potential measurements using a fluorescent dye indicated that two specific toxins active against Spodoptera frugiperda larvae (CryIC and CryID) cause immediate permeability changes in midgut epithelial brush border membrane vesicles (BBMV). The initial response and the sustained permeability change are cationic, not very K+ selective, and occur at in vivo lethal doses (nM). The toxin response has a different ion selectivity and is more sensitive to Ba2+ than the intrinsic cation permeability of BBMV. Experiments incorporating BBMV into planar lipid bilayers (PLB) demonstrated that these vesicles contain cation channels (31, 47 and 76 pS). A 2-40 fold conductance increase was induced by nM concentrations of toxin in PLB containing BBMV. Cationic single channel transitions of 50, 106, 360 and 752 pS were resolved. Thus, Bacillus thuringiensis delta-endotoxins induce an increase in cation membrane permeability involving ion channels in BBMV-containing functional receptors.

Animals↗
PubMed1995

Primary structure of a folate-dependent trifunctional enzyme from Spodoptera frugiperda.

The dehydrogenase and synthetase activities of the NADP-dependent methylenetetra-hydrofolate dehydrogenase-cyclohydrolase-synthetase are undetectable in extracts of the Spodoptera frugiperda cell line, Sf9. However, a single cDNA encoding this protein was isolated from a library and sequenced. The deduced amino acid sequence codes for a protein of 933 amino acids in length that shows 59% identity to the human enzyme. The cDNA inserted in the yeast expression vector pVT102-U complements a purine auxotrophic yeast strain lacking this enzyme.

Amino Acid Sequence↗
PubMed1995

Synthesis and processing of the rubella virus p110 polyprotein precursor in baculovirus-infected Spodoptera frugiperda cells.

In order to study the processing of rubella virus (RV) structural proteins (capsid protein, of 33 kDa; E2 of 42-47 kDa; and E1 of 58 kDa) in Spodoptera frugiperda (fall armyworm) cells, a 24S cDNA encoding the polyprotein precursor, p110, was inserted under the transcriptional regulation of the polyhedrin gene promoter of the Autographa californica nuclear polyhedrosis virus (AcNPV) and expressed during viral infection. By immunoblot analysis using antibodies directed against whole RV and the individual structural proteins, evidence is presented that polypeptides similar to those synthesized in RV-infected B-Vero cells are expressed in this lepidopteran insect cell line infected with the recombinant baculovirus, VL1392-RV24S. The identity of the recombinant proteins was further confirmed using human convalescent sera. By expressing the recombinant proteins in the presence and absence of tunicamycin, we have further demonstrated that the 24S transcription-translation unit of RV, is expressed and proteolytically cleaved similarly, if not identically, in Sf9 cells as compared to B-Vero cells.

Animals↗
PubMed1994

Mitomycin C induced alterations in antioxidant enzyme levels in a model insect species, Spodoptera eridania.

1. An insect species, the southern armyworm Spodoptera eridania, was used as an in vivo model to examine mitomycin C's (MMC) pro-oxidant effect reflected in alterations of antioxidant enzymes. 2. Following a 2-day exposure to 0.01 and 0.05% w/w dietary concentrations, MMC only induced superoxide dismutase activity. All other enzyme activities were not affected, indicating oxidative stress was mild. 3. Following a 5-day exposure to 0.05% w/w dietary MMC, the activities of superoxide dismutase, glutathione-S-transferase and its peroxidase activity and DT-diaphorase were induced. GR activity was not altered. The high constitutive catalase activity was also not affected. These responses of S. eridania's antioxidant enzymes are analogous to those of mammalian systems in alleviating MMC-induced oxidative stress. 4. S. eridania emerges as an appropriate non-mammalian model for initial and cost-effective screening of drug-induced oxidative stress.

Animals↗
PubMed1995

Intracellular signal transduction of PBAN action in the common cutworm, Spodoptera litura: effects of pharmacological agents on sex pheromone production in vitro.

Pheromone biosynthesis activating neuropeptide (PBAN) regulates sex pheromone production in the pheromone glands of many species of female moths. In order to probe the biochemical steps as well as underlying mechanisms regulated by PBAN, we have tested the effects of pharmacological agents on sex pheromone production of the common cutworm, Spodoptera litura, using an in vitro assay. Among the pharmacological agents we tested, ionomycin (calcium ionophore) alone stimulated sex pheromone production, while LaCl3 (calcium channel blocker), W-7, trifluoperazine (calmodulin inhibitor), NaF, and p-nitrophenyl phosphate (phosphatase inhibitor) suppressed the pheromone production by a pheromonotropic peptide, TKYFSPRLamide. By contrast, forskolin (adenylate cyclase activator), phorbol 12-myristate 13-acetate (protein kinase C activator), and cyclic nucleotides alone failed to stimulate sex pheromone production. These results suggest that Ca2+/calmodulin complex and phosphoprotein phosphatase are involved in the signal transduction of PBAN action in S. litura.

Amino Acid Sequence↗
PubMed1996

Digestion of delta-endotoxin by gut proteases may explain reduced sensitivity of advanced instar larvae of Spodoptera littoralis to CryIC.

The present study describes the correlation between gut protease activity of lepidopteran larvae of different instars, the inactivation of Bacillus thuringiensis delta-endotoxins in crystalline and noncrystalline forms, and the reduced susceptibility of advanced larval instars of Spodoptera littoralis to the toxin. The original assembly of delta-endotoxins in a crystal structure is essential for causing efficient larval mortality. Denaturation and renaturation (D/R) of delta-endotoxin crystals increased the vulnerability of the toxin molecules to proteolysis, reduced their capability to kill neonate larvae of S. littoralis, but sustained most of their larval growth-inhibition activity. E. coli-produced CryIC delta-endotoxin applied as a fraction of inclusion bodies exerted a growth inhibition effect, similar to the molecules released from the crystals by denaturation and subsequent renaturation. Incubation of CryIC with gut juice of 1st or 2nd instar larvae, left part of the CryIC toxin intact, while the toxin was completely degraded when incubated with gut juice of 5th instar larvae. The degradation rate was consistent with the increase of protease specific activity of the gut juice during larval development. This increase in toxin degradation may account for the loss of sensitivity of 5th instar larvae to CryIC. Specific protease inhibitors such as PMSF and Leupeptin were shown to inhibit gut proteases activity in all instar larvae, while, 1,10 phenanthroline, TLCK and TPCK were effective only in young instar larvae. The differential effect of protease inhibitors on proteases obtained from different larval instars indicated that gut juice protease profiles change with larval age. The observed quantitative and qualitative differences in degradation of delta-endotoxin by larval gut proteases that occur during larval maturation may account for the difference in susceptibility to the delta-endotoxin. This finding should be taken into consideration when designing strategies for the development of transgenic crops expressing delta-endotoxins as potent insecticidal proteins.

Animals↗
PubMed1996

Synthesis of [14,14,14-2H3] 12-hydroxytetradecanoic acid and [13,14-2H2] 11-hydroxytetradecanoic acid useful as tracers to study a (11E)-desaturation reaction in Spodoptera littoralis.

The synthesis of deuterium labeled 11- and 12-hydroxytetradecanoic acids to study a (11E) desaturase in the moth Spodoptera littoralis is reported. [14,14,14-2H3] 12-hydroxytetradecanoic acid was synthesized in four steps from 11-iodo-1-undecene in 49% overall yield. Deuterium was introduced by reaction of an epoxy ester with (CD3)2CuLi. The preparation of [13,14-2H2] 11-hydroxytetradecanoic acid was carried out in six steps from 11-bromoundecanoic acid in 55% overall yield. In this case, label was introduced by deuteration of an homoallyl alcohol with D2, using the Wilkinson catalyst. Incubation of pheromone glands with either of both acids did not lead to the formation of the labeled (11E)-tetradecenoic acid.

Animals↗
PubMed1996

Difluoropalmitic acids as potential inhibitors of the biosynthesis of the sex pheromone of the Egyptian armyworm Spodoptera littoralis--IV.

2,2-, 3,3- and 4,4-Difluoropalmitic acids (1-3) have been synthesized and fully characterized. Acids 2 and 3 were prepared through fluorination of the corresponding dithioacetal-protected ketoesters followed by enzymatic saponification. The acids 1-3 were evaluated in vivo as inhibitors of the beta-oxidation step of the biosynthesis of (Z,E)-9,11-tetradecadienyl acetate, the major component of the sex pheromone of the Egyptian armyworm Spodoptera littoralis. Only, the 2,2- and 3,3-derivatives, i.e. those containing the two fluorine atoms at the positions involved in the chain-shortened step, have been found to be active, the activity being similar to or lower than that displayed by the corresponding monofluorinated acids.

Animals↗
PubMed2005

Isolation, gene expression and solution structure of a novel moricin analogue, antibacterial peptide from a lepidopteran insect, Spodoptera litura.

An antibacterial peptide was isolated from a lepidopteran insect, Spodoptera litura. The molecular mass of this peptide was determined to be 4489.55 by matrix assisted laser desorption/ionization-time of flight mass (MALDI-TOF MS) spectrometry. The peptide consists of 42 amino acids and the sequence has 69-98% identity to those of moricin-related peptides, antibacterial peptides from lepidopetran insects. Thus, the peptide was designated S. litura (Sl) moricin. Sl moricin showed a broad antibacterial spectrum against Gram-positive and negative bacteria. Sl moricin gene was inducible by bacterial injection and expressed tissue-specifically in the fat body and hemocytes. Furthermore, the solution structure of Sl moricin was determined by two-dimensional (2D) 1H-nuclear magnetic resonance (NMR) spectroscopy and hybrid distance geometry-simulated annealing calculation. The tertiary structure revealed a long alpha-helix containing eight turns along nearly the full length of the peptide like that of moricin, confirming that Sl moricin is a new moricin-like antibacterial peptide. These results suggest that moricin is present not only in B. mori but also in other lepidopteran insects forming a gene family.

Amino Acid Sequence↗
PubMed2005

Immune cascade of Spodoptera litura: cloning, expression, and characterization of inducible prophenol oxidase.

Haemolymph associated phenol oxidase is a critical component of invertebrate immune reaction and cuticle sclerotization. Phenol oxidase catalyses the conversion of mono-phenols to diphenols and quinones which finally leads to melanin formation. We have cloned the c-DNA encoding phenol oxidase from the haemocytes of Spodoptera litura and expressed it in Escherichia coli. The encoding gene is 2452bp with an open reading frame of 2091 bp translating into a 697 amino acid protein. Multiple alignment analysis of the predicted protein sequence shows close homology to other lepidopeteran PPOII type genes. The transcription of the gene is induced upon microbial challenge of 6th instar larvae with E. coli and is unresponsive to injury. Cloning of the ORF of SLPPO in-frame in the E. coli expression vector pQE30 resulted in its expression. Enzymatic analysis of the recombinant protein reveals that the recombinant protein is catalytically active on 4-methyl pyrocatechol upon activation by cetyl pyridinium chloride.

Amino Acid Sequence↗
PubMed2026

Transcriptomic responses to developmental temperature in two field-collected Spodoptera exigua populations from Korea.

The beet armyworm, Spodoptera exigua, is a polyphagous insect whose development and seasonal occurrence are strongly influenced by temperature. However, transcriptomic responses to developmental thermal regimes remain insufficiently characterized in field-collected populations. In this study, we compared two Korean field-collected populations of S. exigua: a Haenam population collected in May and initially maintained at 15 ± 1 °C (HN), and a Jeju population collected in July and initially maintained at 27 ± 1 °C (JJ). F1 larvae from each population were reared under three fluctuating developmental temperature regimes: low (15-21 °C), middle (21-27 °C), and high (27-33 °C), followed by RNA-seq analysis. Differential expression analysis revealed population-associated variation in transcriptomic responses across developmental temperatures. HN exhibited a larger number of differentially expressed genes under the high-temperature regime, suggesting stronger transcriptomic sensitivity to elevated developmental temperature. Functional enrichment analyses identified population-associated differences in pathways related to heat response, oxidative metabolism, cytoskeletal organization, cuticle-associated processes, lipid metabolism, and immune-related functions. In JJ, heat-response and cuticle-related expression patterns were more prominent under warmer developmental conditions, whereas HN showed broader changes in stress- and metabolism-associated pathways under high temperature. Overall, this study provides a comparative transcriptomic analysis of two field-collected S. exigua populations under different developmental temperature regimes and identifies RNA-seq-based molecular response patterns associated with population-specific thermal response profiles.

Animals↗