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Stephane Dupas - One of the best experts on this subject based on the ideXlab platform.
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intraspecific specialization of the generalist parasitoid cotesia sesamiae revealed by polydnavirus polymorphism and associated with different wolbachia infection
Molecular Ecology, 2011Co-Authors: Antoine Branca, Bruno Le Ru, Fabrice Vavre, Jeanfrancois Silvain, Stephane DupasAbstract:As a result of an intense host–parasite evolutionary arms race, parasitic wasps frequently display high levels of specialization on very few host species. For instance, in braconid wasps very few generalist species have been described. However, within this family, Cotesia sesamiae is a generalist species that is widespread in sub-Saharan Africa and develops on several lepidopteran hosts. In this study, we tested the hypothesis that C. sesamiae may be a cryptic specialist when examined at the intraspecific level. We sequenced exon 2 of CrV1, a gene of the symbiotic polyDNAvirus that is integrated into the wasp genome and is associated with host immune suppression. We found that CrV1 genotype was more closely associated with the host in which the parasitoid developed than any abiotic environmental factor tested. We also tested a correlation between CrV1 genotype and an infection with Wolbachia bacteria, which are known for their ability to induce reproductive isolation. The Wolbachia bacteria infection polymorphism was also found as a major factor explaining the genetic structure of CrV1, and, in addition, the best model explaining CrV1 genetic structure involved an interaction between Wolbachia infection and host species. We suggest that Wolbachia could act as an agent capable of maintaining advantageous alleles for host specialization in different populations of C. sesamiae. This mechanism could be applicable to other Insect Models because of the high prevalence of Wolbachia in Insects.
Bruno Le Ru - One of the best experts on this subject based on the ideXlab platform.
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intraspecific specialization of the generalist parasitoid cotesia sesamiae revealed by polydnavirus polymorphism and associated with different wolbachia infection
Molecular Ecology, 2011Co-Authors: Antoine Branca, Bruno Le Ru, Fabrice Vavre, Jeanfrancois Silvain, Stephane DupasAbstract:As a result of an intense host–parasite evolutionary arms race, parasitic wasps frequently display high levels of specialization on very few host species. For instance, in braconid wasps very few generalist species have been described. However, within this family, Cotesia sesamiae is a generalist species that is widespread in sub-Saharan Africa and develops on several lepidopteran hosts. In this study, we tested the hypothesis that C. sesamiae may be a cryptic specialist when examined at the intraspecific level. We sequenced exon 2 of CrV1, a gene of the symbiotic polyDNAvirus that is integrated into the wasp genome and is associated with host immune suppression. We found that CrV1 genotype was more closely associated with the host in which the parasitoid developed than any abiotic environmental factor tested. We also tested a correlation between CrV1 genotype and an infection with Wolbachia bacteria, which are known for their ability to induce reproductive isolation. The Wolbachia bacteria infection polymorphism was also found as a major factor explaining the genetic structure of CrV1, and, in addition, the best model explaining CrV1 genetic structure involved an interaction between Wolbachia infection and host species. We suggest that Wolbachia could act as an agent capable of maintaining advantageous alleles for host specialization in different populations of C. sesamiae. This mechanism could be applicable to other Insect Models because of the high prevalence of Wolbachia in Insects.
Jeanfrancois Silvain - One of the best experts on this subject based on the ideXlab platform.
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intraspecific specialization of the generalist parasitoid cotesia sesamiae revealed by polydnavirus polymorphism and associated with different wolbachia infection
Molecular Ecology, 2011Co-Authors: Antoine Branca, Bruno Le Ru, Fabrice Vavre, Jeanfrancois Silvain, Stephane DupasAbstract:As a result of an intense host–parasite evolutionary arms race, parasitic wasps frequently display high levels of specialization on very few host species. For instance, in braconid wasps very few generalist species have been described. However, within this family, Cotesia sesamiae is a generalist species that is widespread in sub-Saharan Africa and develops on several lepidopteran hosts. In this study, we tested the hypothesis that C. sesamiae may be a cryptic specialist when examined at the intraspecific level. We sequenced exon 2 of CrV1, a gene of the symbiotic polyDNAvirus that is integrated into the wasp genome and is associated with host immune suppression. We found that CrV1 genotype was more closely associated with the host in which the parasitoid developed than any abiotic environmental factor tested. We also tested a correlation between CrV1 genotype and an infection with Wolbachia bacteria, which are known for their ability to induce reproductive isolation. The Wolbachia bacteria infection polymorphism was also found as a major factor explaining the genetic structure of CrV1, and, in addition, the best model explaining CrV1 genetic structure involved an interaction between Wolbachia infection and host species. We suggest that Wolbachia could act as an agent capable of maintaining advantageous alleles for host specialization in different populations of C. sesamiae. This mechanism could be applicable to other Insect Models because of the high prevalence of Wolbachia in Insects.
Célia R. Carlini - One of the best experts on this subject based on the ideXlab platform.
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Insecticidal effect of canavalia ensiformis major urease on nymphs of the milkweed bug oncopeltus fasciatus and characterization of digestive peptidases
Insect Biochemistry and Molecular Biology, 2011Co-Authors: Marina S Defferrari, Diogo Ribeiro Demartini, Thiago Beltram Marcelino, Paulo Marcos Pinto, Célia R. CarliniAbstract:Jackbean (Canavalia ensiformis) ureases are entomotoxic upon the release of internal peptides by Insect's digestive enzymes. Here we studied the digestive peptidases of Oncopeltus fasciatus (milkweed bug) and its susceptibility to jackbean urease (JBU). O. fasciatus nymphs fed urease showed a mortality rate higher than 80% after two weeks. Homogenates of midguts dissected from fourth instars were used to perform proteolytic activity assays. The homogenates hydrolyzed JBU in vitro, yielding a fragment similar in size to known entomotoxic peptides. The major proteolytic activity at pH 4.0 upon protein substrates was blocked by specific inhibitors of aspartic and cysteine peptidases, but not significantly affected by inhibitors of metallopeptidases or serine peptidases. The optimal activity upon N-Cbz-Phe-Arg-MCA was at pH 5.0, with complete blockage by E-64 in all pH tested. Optimal activity upon Abz-AIAFFSRQ-EDDnp (a substrate for aspartic peptidases) was detected at pH 5.0, with partial inhibition by Pepstatin A in the pH range 2-8. Fluorogenic substrates corresponding to the N- and C-terminal regions flanking a known entomotoxic peptide within urease sequence were also tested. While the midgut homogenate did not hydrolyze the N-terminal peptide, it cleaved the C-terminal peptide maximally at pH 4.0-5.0, and this activity was inhibited by E-64 (10 μM). The midgut homogenate was submitted to ion-exchange chromatography followed by gel filtration. A 22 kDa active fraction was obtained, resolved in SDS-PAGE (12%), the corresponding band was in-gel digested by trypsin, the peptides were analyzed by mass spectrometry, retrieving a cathepsin L protein. The purified cathepsin L was shown to have at least two possible cleavage sites within the urease sequence, and might be able to release a known Insecticidal peptide in a single or cascade event. The results suggest that susceptibility of O. fasciatus nymphs to jackbean urease is, like in other Insect Models, due mostly to limited proteolysis of ingested protein and subsequent release of entomotoxic peptide(s) by cathepsin-like digestive enzymes.
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expression kinetics and plasmid stability of recombinant e coli encoding urease derived peptide with bioInsecticide activity
Enzyme and Microbial Technology, 2007Co-Authors: Geizecler Tomazetto, Célia R. Carlini, Fernanda Mulinari, Fernanda Staniscuaski, Beatriz P Settembrini, Marco Antonio Zachia AyubAbstract:Abstract The nucleotide sequence encoding for an Insecticidal peptide derived from the Canavalia ensiformis urease gene jbureII (AF 468788), was cloned and expressed in the pET101/Escherichia coli expression system. Bacterial cultivation in shaker with lactose as inducer produced 1.26 μg of recombinant peptide/mg protein, after 8 h of growth. The plasmid stability and the expression of the recombinant peptide were studied in bioreactor. Expression of the recombinant peptide was strongly affected by pH of cultures, with a decrease of more than 50% when acidification was freely allowed. Likewise, peptide production and plasmid stability were shown to be affected by aeration and agitation speed, both decreasing for higher values of oxygen mass transfer rates. Despite these difficulties, in bioreactor cultures carried out with controlled pH, low oxygen mass transfer rates and using lactose as inducer, we were able to achieve a total peptide production of 7.14 μg/mg protein, which represents approximately 2% of total cell protein. Bioassays were carried out using the purified peptide on Insect Models. The peptide fed to Dysdercus peruvianus nymphs produced 100% mortality after 11 days, deaths starting with a lag phase of 3–4 days, confirming that the bioreactor-produced peptide retained its biological activity.
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jaburetox 2ec an Insecticidal peptide derived from an isoform of urease from the plant canavalia ensiformis
Peptides, 2007Co-Authors: Fernanda Mulinari, Fernanda Staniscuaski, L R Bertholdovargas, Melissa Postal, Osmundo B Oliveiraneto, Daniel J Rigden, Maria Fatima Grossidesa, Célia R. CarliniAbstract:Abstract Canatoxin, a urease isoform from Canavalia ensiformis seeds, shows Insecticidal activity against different Insect species. Its toxicity relies on an internal 10 kDa peptide (pepcanatox), released by hydrolysis of Canatoxin by cathepsins in the digestive system of susceptible Insects. In the present work, based on the N-terminal sequence of pepcanatox, we have designed primers to amplify by PCR a 270-bp fragment corresponding to pepcanatox using JBURE-II cDNA (one of the urease isoforms cloned from C. ensiformis , with high identity to JBURE-I, the classical urease) as a template. This amplicon named jaburetox-2 was cloned into pET 101 vector to obtain heterologous expression in Escherichia coli of the recombinant protein in C-terminal fusion with V-5 epitope and 6-His tag. Jaburetox-2Ec was purified on Nickel-NTA resin and bioassayed in Insect Models. Dysdercus peruvianus larvae were fed on cotton seed meal diets containing 0.01% (w/w) Jaburetox-2Ec and, after 11 days, all individuals were dead. Jaburetox-2Ec was also tested against Spodoptera frugiperda larvae and caused 100% mortality. In contrast, high doses of Jaburetox-2Ec were innocuous when injected or ingested by mice and neonate rats. Modeling of Jaburetox-2Ec, in comparison with other peptide structures, revealed a prominent β-hairpin motif consistent with an Insecticidal activity based on either neurotoxicity or cell permeation.
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biological effects of canatoxin in different Insect Models evidence for a proteolytic activation of the toxin by Insect cathepsinlike enzymes
Journal of Economic Entomology, 1997Co-Authors: Célia R. Carlini, Antonia E A Oliveira, Patricia Azambuja, Jose Xavierfilho, Michael A WellsAbstract:Canatoxin is a toxic protein isolated from the jackbean, Canavalia ensiformis. The toxin injected intraperitoneally is lethal for mice and rats; however, it is inactive if given orally. In this study. Manduca sexta (L.) (Lepidoptera), Schistocerca Americana (Drury) (Orthoptera), Drosophila melanogester (L.) (Diptera), Aedes aegypti (L.) (Diptera), Rhodnius prolixus (Stal)(Hemiptera), and Callosobruchus maculatus (F.) (Coleoptera) were fed on canatoxin- containing diets. No effects were seen in M. sexta, S. Americana, D. melanogaster or A. aegypti . No traces of canatoxin were found in their feces, suggesting that the protein was digested completely by these Insects, which characteristically have a trypsin-based digestion. In contrast, canatoxin was lethal for Insects displaying cathepsin-based digestion. Thus, for C. maculatus , a diet containing 0.25% wt:wt canatoxin caused complete inhibition of larval growth. When R. prolixus were fed on canatoxin, 2 effects were seen: impairment of water excretion and increased lethality 48-96 h after feeding. The lethal effect of canatoxin in R. prolixus was blocked partially or completely when the digestion of the toxin by R. prolixus midgut enzymes was impaired. The data showed that canatoxin is highly toxic when ingested by some species of Insects but not affecting others, probably in correlation with the characteristics of the digestive process of the Insect.
Leslie Pick - One of the best experts on this subject based on the ideXlab platform.
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Oncopeltus-like gene expression patterns in Murgantia histrionica, a new hemipteran model system, suggest ancient regulatory network divergence
EvoDevo, 2020Co-Authors: Jessica Hernandez, Leslie Pick, Katie RedingAbstract:Background Much has been learned about basic biology from studies of Insect model systems. The pre-eminent Insect model system, Drosophila melanogaster , is a holometabolous Insect with a derived mode of segment formation. While additional Insect Models have been pioneered in recent years, most of these fall within holometabolous lineages. In contrast, hemimetabolous Insects have garnered less attention, although they include agricultural pests, vectors of human disease, and present numerous evolutionary novelties in form and function. The milkweed bug, Oncopeltus fasciatus (order: Hemiptera)—close outgroup to holometabolous Insects—is an emerging model system. However, comparative studies within this order are limited as many phytophagous hemipterans are difficult to stably maintain in the lab due to their reliance on fresh plants, deposition of eggs within plant material, and long development time from embryo to adult. Results Here we present the harlequin bug, Murgantia histrionica , as a new hemipteran model species. Murgantia —a member of the stink bug family Pentatomidae which shares a common ancestor with Oncopeltus ~ 200 mya—is easy to rear in the lab, produces a large number of eggs, and is amenable to molecular genetic techniques. We use Murgantia to ask whether Pair-Rule Genes (PRGs) are deployed in ways similar to holometabolous Insects or to Oncopeltus . Specifically, PRGs even - skipped, odd - skipped, paired and sloppy - paired are initially expressed in PR-stripes in Drosophila and a number of holometabolous Insects but in segmental-stripes in Oncopeltus . We found that these genes are likewise expressed in segmental-stripes in Murgantia, while runt displays partial PR-character in both species. Also like Oncopeltus , E75A is expressed in a clear PR-pattern in blastoderm- and germband-stage Murgantia embryos, although it plays no role in segmentation in Drosophila . Thus, genes diagnostic of the split between holometabolous Insects and Oncopeltus are expressed in an Oncopeltus -like fashion during Murgantia development. Conclusions The similarity in gene expression between Murgantia and Oncopeltus suggests that Oncopeltus is not a sole outlier species in failing to utilize orthologs of Drosophila PRGs for PR-patterning. Rather, strategies deployed for PR-patterning, including the use of E75A in the PRG-network, are likely conserved within Hemiptera, and possibly more broadly among hemimetabolous Insects.
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conservation and variation in hox genes how Insect Models pioneered the evo devo field
Annual Review of Entomology, 2013Co-Authors: Alison Heffer, Leslie PickAbstract:Evolutionary developmental biology, or evo-devo, broadly investigates how body plan diversity and morphological novelties have arisen and persisted in nature. The discovery of Hox genes in Drosophila, and their subsequent identification in most other metazoans, led biologists to try to understand how embryonic genes crucial for proper development have changed to promote the vast morphological variation seen in nature. Insects are ideal model systems for studying this diversity and the mechanisms underlying it because phylogenetic relationships are well established, powerful genetic tools have been developed, and there are many examples of evolutionary specializations that have arisen in nature in different Insect lineages, such as the jumping leg of orthopterans and the helmet structures of treehoppers. Here, we briefly introduce the field of evo-devo and Hox genes, discuss functional tools available to study early developmental genes in Insects, and provide examples in which changes in Hox genes have contributed to changes in body plan or morphology.