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1.
Scand J Public Health ; : 14034948211048050, 2021 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-34664529

RESUMO

Aims: To assess SARS-CoV-2 seroprevalence over the first epidemic wave in the canton of Geneva, Switzerland, as well as risk factors for infection and symptoms associated with IgG seropositivity. Methods: Between April and June 2020, former participants of a representative survey of the 20-74-year-old population of canton Geneva were invited to participate in the study, along with household members aged over 5 years. Blood samples were tested for anti-SARS-CoV-2 immunoglobulin G. Questionnaires were self-administered. We estimated seroprevalence with a Bayesian model accounting for test performance and sampling design. Results: We included 8344 participants, with an overall adjusted seroprevalence of 7.8% (95% credible interval 6.8-8.9). Seroprevalence was highest among 18-49 year-olds (9.5%), and lowest in 5-9-year-old children (4.3%) and individuals >65 years (4.7-5.4%). Odds of seropositivity were significantly reduced for female retirees and unemployed men compared to employed individuals, and smokers compared to non-smokers. We found no significant association between occupation, level of education, neighborhood income and the risk of being seropositive. The symptom most strongly associated with seropositivity was anosmia/dysgeusia. Conclusions: Anti-SARS-CoV-2 population seroprevalence remained low after the first wave in Geneva. Socioeconomic factors were not associated with seropositivity in this sample. The elderly, young children and smokers were less frequently seropositive, although it is not clear how biology and behaviours shape these differences.

2.
BMC Plant Biol ; 21(1): 358, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34348650

RESUMO

BACKGROUND: The South America pinworm, Tuta absoluta, is a destructive pest of tomato that causes important losses worldwide. Breeding of resistant/tolerant tomato cultivars could be an effective strategy for T. absoluta management but, despite the economic importance of tomato, very limited information is available about its response to this treat. To elucidate the defense mechanisms to herbivore feeding a comparative analysis was performed between a tolerant and susceptible cultivated tomato at both morphological and transcriptome level to highlight constitutive leaf barriers, molecular and biochemical mechanisms to counter the effect of T. absoluta attack. RESULTS: The tolerant genotype showed an enhanced constitutive barrier possibly as result of the higher density of trichomes and increased inducible reactions upon mild infestation thanks to the activation/repression of key transcription factors regulating genes involved in cuticle formation and cell wall strength as well as of antinutritive enzymes, and genes involved in the production of chemical toxins and bioactive secondary metabolites. CONCLUSIONS: Overall, our findings suggest that tomato resilience to the South America pinworm is achieved by a combined strategy between constitutive and induced defense system. A well-orchestrated modulation of plant transcription regulation could ensure a trade-off between defense needs and fitness costs. Our finding can be further exploited for developing T. absoluta tolerant cultivars, acting as important component of integrated pest management strategy for more sustainable production.


Assuntos
Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Folhas de Planta/genética , Transcriptoma , Animais , Perfilação da Expressão Gênica/métodos , Ontologia Genética , Interações Hospedeiro-Parasita , Larva/fisiologia , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/parasitologia , Mariposas/fisiologia , Doenças das Plantas/parasitologia , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA-Seq/métodos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Tricomas/genética , Tricomas/metabolismo , Tricomas/parasitologia
3.
Nat Commun ; 12(1): 3455, 2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103517

RESUMO

Limited data exist on SARS-CoV-2 infection rates across sectors and occupations, hindering our ability to make rational policy, including vaccination prioritization, to protect workers and limit SARS-CoV-2 spread. Here, we present results from our SEROCoV-WORK + study, a serosurvey of workers recruited after the first wave of the COVID-19 pandemic in Geneva, Switzerland. We tested workers (May 18-September 18, 2020) from 16 sectors and 32 occupations for anti-SARS-CoV-2 IgG antibodies. Of 10,513 participants, 1026 (9.8%) tested positive. The seropositivity rate ranged from 4.2% in the media sector to 14.3% in the nursing home sector. We found considerable within-sector variability: nursing home (0%-31.4%), homecare (3.9%-12.6%), healthcare (0%-23.5%), public administration (2.6%-24.6%), and public security (0%-16.7%). Seropositivity rates also varied across occupations, from 15.0% among kitchen staff and 14.4% among nurses, to 5.4% among domestic care workers and 2.8% among journalists. Our findings show that seropositivity rates varied widely across sectors, between facilities within sectors, and across occupations, reflecting a higher exposure in certain sectors and occupations.


Assuntos
Anticorpos Antivirais/imunologia , SARS-CoV-2/imunologia , Adolescente , Adulto , Idoso , COVID-19/epidemiologia , COVID-19/imunologia , Feminino , Humanos , Imunoglobulina G/imunologia , Masculino , Pessoa de Meia-Idade , Prevalência , Tamanho da Amostra , Suíça/epidemiologia , Adulto Jovem
5.
PLoS Pathog ; 16(12): e1009075, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33275645

RESUMO

Varroa destructor is an ectoparasite of honey bees and an active disease vector, which represents one of the most severe threats for the beekeeping industry. This parasitic mite feeds on the host's body fluids through a wound in the cuticle, which allows food uptake by the mother mite and its progeny, offering a potential route of entrance for infecting microorganisms. Mite feeding is associated with saliva injection, whose role is still largely unknown. Here we try to fill this gap by identifying putative host regulation factors present in the saliva of V. destructor and performing a functional analysis for one of them, a chitinase (Vd-CHIsal) phylogenetically related to chitinases present in parasitic and predatory arthropods, which shows a specific and very high level of expression in the mite's salivary glands. Vd-CHIsal is essential for effective mite feeding and survival, since it is apparently involved both in maintaining the feeding wound open and in preventing host infection by opportunistic pathogens. Our results show the important role in the modulation of mite-honey bee interactions exerted by a host regulation factor shared by different evolutionary lineages of parasitic arthropods. We predict that the functional characterization of Varroa sialome will provide new background knowledge on parasitism evolution in arthropods and the opportunity to develop new bioinspired strategies for mite control based on the disruption of their complex interactions with a living food source.


Assuntos
Interações Hospedeiro-Parasita/fisiologia , Saliva/enzimologia , Varroidae/metabolismo , Animais , Criação de Abelhas/métodos , Abelhas/imunologia , Abelhas/metabolismo , Abelhas/parasitologia , Quitinases/metabolismo , Imunidade , Pupa/parasitologia , Saliva/química , Glândulas Salivares/metabolismo , Varroidae/patogenicidade , Varroidae/fisiologia
6.
Nat Commun ; 11(1): 5887, 2020 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-33208729

RESUMO

The neonicotinoid Clothianidin has a negative impact on NF-κB signaling and on immune responses controlled by this transcription factor, which can boost the proliferation of honey bee parasites and pathogens. This effect has been well documented for the replication of deformed wing virus (DWV) induced by Clothianidin in honey bees bearing an asymptomatic infection. Here, we conduct infestation experiments of treated bees to show that the immune-suppression exerted by Clothianidin is associated with an enhanced fertility of the parasitic mite Varroa destructor, as a possible consequence of a higher feeding efficiency. A conceptual model is proposed to describe the synergistic interactions among different stress agents acting on honey bees.


Assuntos
Abelhas/efeitos dos fármacos , Abelhas/imunologia , Guanidinas/toxicidade , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Tiazóis/toxicidade , Varroidae/crescimento & desenvolvimento , Animais , Abelhas/parasitologia , Interações Hospedeiro-Parasita , Varroidae/fisiologia
7.
Pest Manag Sci ; 76(9): 3199-3207, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32358914

RESUMO

BACKGROUND: The olive fruit fly Bactrocera oleae (Rossi) (OLF) is a major agricultural pest, whose control primarily relies on the use of chemical insecticides. Therefore, development of sustainable control strategies is highly desirable. The primary endosymbiotic bacterium of OLF, 'Candidatus Erwinia dacicola', is essential for successful larval development in unripe olive fruits. Therefore, targeting this endosymbiont with antimicrobial compounds may result in OLF fitness reduction and may exert control on natural populations of OLF. RESULTS: Here, we evaluate the impact of compounds with antimicrobial activity on the OLF endosymbiont. Copper oxychloride (CO) and the fungal metabolite viridiol (Vi), produced by Trichoderma spp., were used. Laboratory bioassays were carried out to assess the effect of oral administration of these compounds on OLF fitness and molecular analyses (quantitative polymerase chain reaction) were conducted to measure the load of OLF-associated microorganisms in treated flies. CO and Vi were both able to disrupt the symbiotic association between OLF and its symbiotic bacteria, determining a significant reduction in the endosymbiont and gut microbiota load as well as a decrease in OLF fitness. CO had a direct negative effect on OLF adults. Conversely, exposure to Vi significantly undermined larval development of the treated female's progeny but did not show any toxicity in OLF adults. CONCLUSIONS: These results provide new insights into the symbiotic control of OLF and pave the way for the development of more sustainable strategies of pest control based on the use of natural compounds with antimicrobial activity. © 2020 Society of Chemical Industry.


Assuntos
Erwinia , Olea , Tephritidae , Animais , Drosophila , Feminino , Frutas , Simbiose
8.
BMC Genomics ; 21(1): 34, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924169

RESUMO

BACKGROUND: Venom is one of the most important sources of regulation factors used by parasitic Hymenoptera to redirect host physiology in favour of the developing offspring. This has stimulated a number of studies, both at functional and "omics" level, which, however, are still quite limited for ectophagous parasitoids that permanently paralyze and suppress their victims (i.e., idiobiont parasitoids). RESULTS: Here we present a combined transcriptomic and proteomic study of the venom of the generalist idiobiont wasp Bracon nigricans, an ectophagous larval parasitoid of different lepidopteran species, for which we recently described the host regulation strategy and the functional role of the venom in the induction of physiological changes in parasitized hosts. The experimental approach used led to the identification of the main components of B. nigricans venom involved in host regulation. Enzymes degrading lipids, proteins and carbohydrates are likely involved in the mobilization of storage nutrients from the fat body and may concurrently be responsible for the release of neurotoxic fatty acids inducing paralysis, and for the modulation of host immune responses. CONCLUSION: The present work contributes to fill the gap of knowledge on venom composition in ectoparasitoid wasps, and, along with our previous physiological study on this species, provides the foundation on which to develop a functional model of host regulation, based both on physiological and molecular data. This paves the way towards a better understanding of parasitism evolution in the basal lineages of Hymenoptera and to the possible exploitation of venom as source of bioinsecticidal molecules.


Assuntos
Venenos de Vespas/metabolismo , Vespas/metabolismo , Animais , Interações Hospedeiro-Parasita , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteômica , Transcriptoma/genética , Venenos de Vespas/genética , Vespas/genética
9.
BMC Genomics ; 20(1): 893, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31752718

RESUMO

BACKGROUND: Parasitic insects are well-known biological control agents for arthropod pests worldwide. They are capable of regulating their host's physiology, development and behaviour. However, many of the molecular mechanisms involved in host-parasitoid interaction remain unknown. RESULTS: We sequenced the genomes of two parasitic wasps (Cotesia vestalis, and Diadromus collaris) that parasitize the diamondback moth Plutella xylostella using Illumina and Pacbio sequencing platforms. Genome assembly using SOAPdenovo produced a 178 Mb draft genome for C. vestalis and a 399 Mb draft genome for D. collaris. A total set that contained 11,278 and 15,328 protein-coding genes for C. vestalis and D. collaris, respectively, were predicted using evidence (homology-based and transcriptome-based) and de novo prediction methodology. Phylogenetic analysis showed that the braconid C. vestalis and the ichneumonid D. collaris diverged approximately 124 million years ago. These two wasps exhibit gene gains and losses that in some cases reflect their shared life history as parasitic wasps and in other cases are unique to particular species. Gene families with functions in development, nutrient acquisition from hosts, and metabolism have expanded in each wasp species, while genes required for biosynthesis of some amino acids and steroids have been lost, since these nutrients can be directly obtained from the host. Both wasp species encode a relative higher number of neprilysins (NEPs) thus far reported in arthropod genomes while several genes encoding immune-related proteins and detoxification enzymes were lost in both wasp genomes. CONCLUSIONS: We present the annotated genome sequence of two parasitic wasps C. vestalis and D. collaris, which parasitize a common host, the diamondback moth, P. xylostella. These data will provide a fundamental source for studying the mechanism of host control and will be used in parasitoid comparative genomics to study the origin and diversification of the parasitic lifestyle.


Assuntos
Genoma de Inseto , Mariposas/parasitologia , Vespas/genética , Animais , Genes de Insetos , Imunidade/genética , Família Multigênica , Filogenia , Vespas/classificação
10.
Plants (Basel) ; 8(10)2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31623335

RESUMO

Plant defense peptides represent an important class of compounds active against pathogens and insects. These molecules controlling immune barriers can potentially be used as novel tools for plant protection, which mimic natural defense mechanisms against invaders. The constitutive expression in tomato plants of the precursor of the defense peptide systemin was previously demonstrated to increase tolerance against moth larvae and aphids and to hamper the colonization by phytopathogenic fungi, through the expression of a wealth of defense-related genes. In this work we studied the impact of the exogenous supply of systemin to tomato plants on pests to evaluate the use of the peptide as a tool for crop protection in non-transgenic approaches. By combining gene expression studies and bioassays with different pests we demonstrate that the exogenous supply of systemin to tomato plants enhances both direct and indirect defense barriers. Experimental plants, exposed to this peptide by foliar spotting or root uptake through hydroponic culture, impaired larval growth and development of the noctuid moth Spodoptera littoralis, even across generations, reduced the leaf colonization by the fungal pathogen Botrytis cinerea and were more attractive towards natural herbivore antagonists. The induction of these defense responses was found to be associated with molecular and biochemical changes under control of the systemin signalling cascade. Our results indicate that the direct delivery of systemin, likely characterized by a null effect on non-target organisms, represents an interesting tool for the sustainable protection of tomato plants.

11.
Front Physiol ; 10: 745, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31293434

RESUMO

Beneficial fungi in the genus Trichoderma are among the most widespread biocontrol agents of plant pathogens. Their role in triggering plant defenses against pathogens has been intensely investigated, while, in contrast, very limited information is available on induced barriers active against insects. The growing experimental evidence on this latter topic looks promising, and paves the way toward the development of Trichoderma strains and/or consortia active against multiple targets. However, the predictability and reproducibility of the effects that these beneficial fungi is still somewhat limited by the lack of an in-depth understanding of the molecular mechanisms underlying the specificity of their interaction with different crop varieties, and on how the environmental factors modulate this interaction. To fill this research gap, here we studied the transcriptome changes in tomato plants (cultivar "Dwarf San Marzano") induced by Trichoderma harzianum (strain T22) colonization and subsequent infestation by the aphid Macrosiphum euphorbiae. A wide transcriptome reprogramming, related to metabolic processes, regulation of gene expression and defense responses, was induced both by separate experimental treatments, which showed a synergistic interaction when concurrently applied. The most evident expression changes of defense genes were associated with the multitrophic interaction Trichoderma-tomato-aphid. Early and late genes involved in direct defense against insects were induced (i.e., peroxidase, GST, kinases and polyphenol oxidase, miraculin, chitinase), along with indirect defense genes, such as sesquiterpene synthase and geranylgeranyl phosphate synthase. Targeted and untargeted semi-polar metabolome analysis revealed a wide metabolome alteration showing an increased accumulation of isoprenoids in Trichoderma treated plants. The wide array of transcriptomic and metabolomics changes nicely fit with the higher mortality of aphids when feeding on Trichoderma treated plants, herein reported, and with the previously observed attractiveness of these latter toward the aphid parasitoid Aphidius ervi. Moreover, Trichoderma treated plants showed the over-expression of transcripts coding for several families of defense-related transcription factors (bZIP, MYB, NAC, AP2-ERF, WRKY), suggesting that the fungus contributes to the priming of plant responses against pest insects. Collectively, our data indicate that Trichoderma treatment of tomato plants induces transcriptomic and metabolomic changes, which underpin both direct and indirect defense responses.

12.
Front Physiol ; 10: 813, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31333483

RESUMO

Numerous microbial root symbionts are known to induce different levels of enhanced plant protection against a variety of pathogens. However, more recent studies have demonstrated that beneficial microbes are able to induce plant systemic resistance that confers some degree of protection against insects. Here, we report how treatments with the fungal biocontrol agent Trichoderma atroviride strain P1 in tomato plants induce responses that affect pest insects with different feeding habits: the noctuid moth Spodoptera littoralis (Boisduval) and the aphid Macrosiphum euphorbiae (Thomas). We observed that the tomato plant-Trichoderma P1 interaction had a negative impact on the development of moth larvae and on aphid longevity. These effects were attributed to a plant response induced by Trichoderma that was associated with transcriptional changes of a wide array of defense-related genes. While the impact on aphids could be related to the up-regulation of genes involved in the oxidative burst reaction, which occur early in the defense reaction, the negative performance of moth larvae was associated with the enhanced expression of genes encoding for protective enzymes (i.e., Proteinase inhibitor I (PI), Threonine deaminase, Leucine aminopeptidase A1, Arginase 2, and Polyphenol oxidase) that are activated downstream in the defense cascade. In addition, Trichoderma P1 produced alterations in plant metabolic pathways leading to the production and release of volatile organic compounds (VOCs) that are involved in the attraction of the aphid parasitoid Aphidius ervi, thus reinforcing the indirect plant defense barriers. Our findings, along with the evidence available in the literature, indicate that the outcome of the tripartite interaction among plant, Trichoderma, and pests is highly specific and only a comprehensive approach, integrating both insect phenotypic changes and plant transcriptomic alterations, can allow a reliable prediction of its potential for plant protection.

13.
Pest Manag Sci ; 75(9): 2505-2516, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31207012

RESUMO

BACKGROUND: Potassium ion channels play a critical role in the generation of electrical signals and thus provide potential targets for control of insect pests by RNA interference. RESULTS: Genes encoding the small conductance calcium-activated potassium channel (SK) and the voltage-gated potassium channel (SH) were knocked down in Tribolium castaneum by injection and oral delivery of dsRNA (dsTcSK and dsTcSH, respectively). Irrespective of the delivery mechanism a dose-dependent effect was observed for knockdown (KD) of gene expression and insect mortality for both genes. Larvae fed a 400 ng dsRNA mg-1 diet showed significant gene (P < 0.05) knockdown (98% and 83%) for SK and SH, respectively, with corresponding mortalities of 100% and 98% after 7 days. When injected (248.4 ng larva-1 ), gene KD was 99% and 98% for SK and SH, causing 100% and 73.4% mortality, respectively. All developmental stages tested (larvae, early- and late-stage pupae and adults) showed an RNAi-sensitive response for both genes. LC50 values were lower for SK than SH, irrespective of delivery method, demonstrating that the knockdown of SK had a greater effect on larval mortality. Biosafety studies using adult honeybee Apis mellifera showed that there were no significant differences either in expression levels or mortality of honeybees orally dosed with dsTcSK and dsTcSH compared to control-fed bees. Similarly, there was no significant difference in the titre of deformed wing virus, used as a measure of immune suppression, between experimental and control bees. CONCLUSION: This study demonstrates the potential of using RNAi targeting neural receptors as a technology for the control of T. castaneum. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Controle de Insetos/métodos , Proteínas de Insetos/antagonistas & inibidores , Bloqueadores dos Canais de Potássio/metabolismo , Tribolium/efeitos dos fármacos , Animais , Técnicas de Silenciamento de Genes , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Pupa/efeitos dos fármacos , Pupa/genética , Pupa/crescimento & desenvolvimento , Interferência de RNA , RNA de Cadeia Dupla/genética , Canais de Potássio Ativados por Cálcio de Condutância Baixa/antagonistas & inibidores , Tribolium/genética , Tribolium/crescimento & desenvolvimento
14.
Struct Dyn ; 6(2): 024304, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31041361

RESUMO

We demonstrate that highly ordered two-dimensional crystals of ligand-capped gold nanoparticles display a local photo-mechanical stiffness as high as that of solids such as graphite. In out-of-equilibrium electron diffraction experiments, a strong temperature jump is induced in a thin film with a femtosecond laser pulse. The initial electronic excitation transfers energy to the underlying structural degrees of freedom, with a rate generally proportional to the stiffness of the material. Using femtosecond small-angle electron diffraction, we observe the temporal evolution of the diffraction feature associated with the nearest-neighbor nanoparticle distance. The Debye-Waller decay for the octanethiol-capped nanoparticle supracrystal, in particular, is found to be unexpectedly fast, almost as fast as the stiffest solid known and observed by the same technique, i.e., graphite. Our observations unravel that local stiffness in a dense supramolecular assembly can be created by van der Waals interactions up to a level comparable to crystalline systems characterized by covalent bonding.

15.
Proc Biol Sci ; 286(1901): 20190331, 2019 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-30991929

RESUMO

The association between the deformed wing virus and the parasitic mite Varroa destructor has been identified as a major cause of worldwide honeybee colony losses. The mite acts as a vector of the viral pathogen and can trigger its replication in infected bees. However, the mechanistic details underlying this tripartite interaction are still poorly defined, and, particularly, the causes of viral proliferation in mite-infested bees. Here, we develop and test a novel hypothesis that mite feeding destabilizes viral immune control through the removal of both virus and immune effectors, triggering uncontrolled viral replication. Our hypothesis is grounded on the predator-prey theory developed by Volterra, which predicts prey proliferation when both predators and preys are constantly removed from the system. Consistent with this hypothesis, we show that the experimental removal of increasing volumes of haemolymph from individual bees results in increasing viral densities. By contrast, we do not find consistent support for alternative proposed mechanisms of viral expansion via mite immune suppression or within-host viral evolution. Our results suggest that haemolymph removal plays an important role in the enhanced pathogen virulence observed in the presence of feeding Varroa mites. Overall, these results provide a new model for the mechanisms driving pathogen-parasite interactions in bees, which ultimately underpin honeybee health decline and colony losses.


Assuntos
Abelhas/imunologia , Hemolinfa/fisiologia , Interações Hospedeiro-Parasita , Vírus de RNA/fisiologia , Varroidae/fisiologia , Replicação Viral , Animais , Abelhas/crescimento & desenvolvimento , Abelhas/parasitologia , Abelhas/virologia , Comportamento Alimentar , Larva/crescimento & desenvolvimento , Larva/imunologia , Larva/parasitologia , Larva/virologia , Pupa/crescimento & desenvolvimento , Pupa/imunologia , Pupa/parasitologia , Pupa/virologia , Varroidae/crescimento & desenvolvimento
16.
PLoS Genet ; 15(3): e1007998, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30835731

RESUMO

Genome sequencing data have recently demonstrated that eukaryote evolution has been remarkably influenced by the acquisition of a large number of genes by horizontal gene transfer (HGT) across different kingdoms. However, in depth-studies on the physiological traits conferred by these accidental DNA acquisitions are largely lacking. Here we elucidate the functional role of Sl gasmin, a gene of a symbiotic virus of a parasitic wasp that has been transferred to an ancestor of the moth species Spodoptera littoralis and domesticated. This gene is highly expressed in circulating immune cells (haemocytes) of larval stages, where its transcription is rapidly boosted by injection of microorganisms into the body cavity. RNAi silencing of Sl gasmin generates a phenotype characterized by a precocious suppression of phagocytic activity by haemocytes, which is rescued when these immune cells are incubated in plasma samples of control larvae, containing high levels of the encoded protein. Proteomic analysis demonstrates that the protein Sl gasmin is released by haemocytes into the haemolymph, where it opsonizes the invading bacteria to promote their phagocytosis, both in vitro and in vivo. Our results show that important physiological traits do not necessarily originate from evolution of pre-existing genes, but can be acquired by HGT events, through unique pathways of symbiotic evolution. These findings indicate that insects can paradoxically acquire selective advantages with the help of their natural enemies.


Assuntos
Evolução Molecular , Transferência Genética Horizontal/genética , Larva/imunologia , Vespas/imunologia , Animais , Hemolinfa/imunologia , Hemolinfa/virologia , Larva/genética , Larva/virologia , Filogenia , Proteômica , Simbiose/genética , Simbiose/imunologia , Vespas/genética , Vespas/virologia
17.
Insect Biochem Mol Biol ; 95: 26-32, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29559251

RESUMO

Polydnaviruses (PDV) are viral symbionts associated with ichneumonid and braconid wasps parasitizing moth larvae, which are able to disrupt the host immune response and development, as well as a number of other physiological pathways. The immunosuppressive role of PDV has been more intensely investigated, while very little is known about the PDV-encoded factors disrupting host development. Here we address this research issue by further expanding the functional analysis of ankyrin genes encoded by the bracovirus associated with Toxoneuron nigriceps (Hymenoptera, Braconidae). In a previous study, using Drosophila melanogaster as experimental model system, we demonstrated the negative impact of TnBVank1 impairing the ecdysone biosynthesis by altering endocytic traffic in prothoracic gland cells. With a similar approach here we demonstrate that another member of the viral ank gene family, TnBVank3, does also contribute to the disruption of ecdysone biosynthesis, but with a completely different mechanism. We show that its expression in Drosophila prothoracic gland (PG) blocks the larval-pupal transition by impairing the expression of steroidogenic genes. Furthermore, we found that TnBVank3 affects the expression of genes involved in the insulin/TOR signaling and the constitutive activation of the insulin pathway in the PG rescues the pupariation impairment. Collectively, our data demonstrate that TnBVANK3 acts as a virulence factor by exerting a synergistic and non-overlapping function with TnBVANK1 to disrupt the ecdysone biosynthesis.


Assuntos
Anquirinas/metabolismo , Ecdisona/biossíntese , Regulação da Expressão Gênica , Himenópteros/virologia , Polydnaviridae/metabolismo , Proteínas Virais/metabolismo , Animais , Anquirinas/genética , Drosophila melanogaster , Ecdisona/genética , Polydnaviridae/genética , Proteínas Virais/genética
18.
Viruses ; 10(4)2018 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-29601473

RESUMO

Any attempt to outline a logical framework in which to interpret the honey bee health decline and its contribution to elevated colony losses should recognize the importance of the multifactorial nature of the responsible syndrome and provide a functional model as a basis for defining and testing working hypotheses. We propose that covert infections by deformed wing virus (DWV) represent a sword of Damocles permanently threatening the survival of honey bee colonies and suggest that any factor affecting the honey bee’s antiviral defenses can turn this pathogen into a killer. Here we discuss the available experimental evidence in the framework of a model based on honey bee immune competence as affected by multiple stress factors that is proposed as a conceptual tool for analyzing bee mortality and its underlying mechanisms.


Assuntos
Abelhas/imunologia , Colapso da Colônia , Modelos Imunológicos , Animais , Abelhas/microbiologia , Abelhas/parasitologia , Abelhas/virologia , Inseticidas , Microbiota , Neonicotinoides , Vírus de RNA/fisiologia , Simbiose , Varroidae/fisiologia
19.
Protein Sci ; 27(3): 620-632, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29168260

RESUMO

Prosystemin, originally isolated from Lycopersicon esculentum, is a tomato pro-hormone of 200 aminoacid residues which releases a bioactive peptide of 18 aminoacids called Systemin. This signaling peptide is involved in the activation of defense genes in solanaceous plants in response to herbivore feeding damage. Using biochemical, biophysical and bioinformatics approaches we characterized Prosystemin, showing that it is an intrinsically disordered protein possessing a few secondary structure elements within the sequence. Plant treatment with recombinant Prosystemin promotes early and late plant defense genes, which limit the development and survival of Spodoptera littoralis larvae fed with treated plants.


Assuntos
Lycopersicon esculentum/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/farmacologia , Spodoptera/crescimento & desenvolvimento , Animais , Dicroísmo Circular , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/farmacologia , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Lycopersicon esculentum/química , Lycopersicon esculentum/genética , Modelos Moleculares , Ressonância Magnética Nuclear Biomolecular , Proteínas de Plantas/metabolismo , Estrutura Secundária de Proteína , Spodoptera/efeitos dos fármacos
20.
Sci Rep ; 7(1): 15522, 2017 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-29138416

RESUMO

Plants actively respond to herbivory by inducing various defense mechanisms in both damaged (locally) and non-damaged tissues (systemically). In addition, it is currently widely accepted that plant-to-plant communication allows specific neighbors to be warned of likely incoming stress (defense priming). Systemin is a plant peptide hormone promoting the systemic response to herbivory in tomato. This 18-aa peptide is also able to induce the release of bioactive Volatile Organic Compounds, thus also promoting the interaction between the tomato and the third trophic level (e.g. predators and parasitoids of insect pests). In this work, using a combination of gene expression (RNA-Seq and qRT-PCR), behavioral and chemical approaches, we demonstrate that systemin triggers metabolic changes of the plant that are capable of inducing a primed state in neighboring unchallenged plants. At the molecular level, the primed state is mainly associated with an elevated transcription of pattern -recognition receptors, signaling enzymes and transcription factors. Compared to naïve plants, systemin-primed plants were significantly more resistant to herbivorous pests, more attractive to parasitoids and showed an increased response to wounding. Small peptides are nowadays considered fundamental signaling molecules in many plant processes and this work extends the range of downstream effects of this class of molecules to intraspecific plant-to-plant communication.


Assuntos
Comunicação Autócrina/genética , Regulação da Expressão Gênica de Plantas/imunologia , Lycopersicon esculentum/metabolismo , Peptídeos/genética , Imunidade Vegetal/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Sequência de Aminoácidos , Animais , Comunicação Autócrina/imunologia , Ontologia Genética , Herbivoria/fisiologia , Larva/fisiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/imunologia , Lycopersicon esculentum/parasitologia , Anotação de Sequência Molecular , Peptídeos/síntese química , Peptídeos/imunologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Proteínas de Plantas/classificação , Proteínas de Plantas/imunologia , Receptores de Reconhecimento de Padrão/genética , Transdução de Sinais , Spodoptera/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/imunologia , Transcrição Genética , Compostos Orgânicos Voláteis/imunologia , Compostos Orgânicos Voláteis/metabolismo
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