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1.
Proc Biol Sci ; 287(1934): 20201311, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32873204

RESUMO

Phytophagous insects can tolerate and detoxify toxic compounds present in their host plants and have evolved intricate adaptations to this end. Some insects even sequester the toxins for their defence. This necessitates specific mechanisms, especially carrier proteins that regulate uptake and transport to specific storage sites or protect sensitive tissues from noxious compounds. We identified three ATP-binding cassette subfamily B (ABCB) transporters from the transcriptome of the cardenolide-sequestering leaf beetle Chrysochus auratus and analysed their functional role in the sequestration process. These were heterologously expressed and tested for their ability to interact with various potential substrates: verapamil (standard ABCB substrate), the cardenolides digoxin (commonly used), cymarin (present in the species's host plant) and calotropin (present in the ancestral host plants). Verapamil stimulated all three ABCBs and each was activated by at least one cardenolide, however, they differed as to which they were activated by. While the expression of the most versatile transporter fits with a protective role in the blood-brain barrier, the one specific for cymarin shows an extreme abundance in the elytra, coinciding with the location of the defensive glands. Our data thus suggest a key role of ABCBs in the transport network needed for cardenolide sequestration.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Besouros/fisiologia , Proteínas de Insetos/metabolismo , Proteínas de Plantas/toxicidade , Animais
2.
PLoS One ; 15(8): e0234892, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817668

RESUMO

The mosquito Aedes aegypti vectors the arboviral diseases yellow fever, dengue, Zika and chikungunya. Larvae are usually found developing in freshwater; however, more recently they have been increasingly found in brackish water, potential habitats which are traditionally ignored by mosquito control programs. Aedes aegypti larvae are osmo-regulators maintaining their hemolymph osmolarity in a range of ~ 250 to 300 mOsmol l-1. In freshwater, the larvae must excrete excess water while conserving ions while in brackish water, they must alleviate an accumulation of salts. The compensatory physiological mechanisms must involve the transport of ions and water but little is known about the water transport mechanisms in the osmoregulatory organs of these larvae. Water traverses cellular membranes predominantly through transmembrane proteins named aquaporins (AQPs) and Aedes aegypti possesses 6 AQP homologues (AaAQP1 to 6). The objective of this study was to determine if larvae that develop in freshwater or brackish water have differential aquaporin expression in osmoregulatory organs, which could inform us about the relative importance and function of aquaporins to mosquito survival under these different osmotic conditions. We found that AaAQP transcript abundance was similar in organs of freshwater and brackish water mosquito larvae. Furthermore, in the Malpighian tubules and hindgut AaAQP protein abundance was unaffected by the rearing conditions, but in the gastric caeca the protein level of one aquaporin, AaAQP1 was elevated in brackish water. We found that AaAQP1 was expressed apically while AaAQP4 and AaAQP5 were found to be apical and/or basal in the epithelia of osmoregulatory organs. Overall, the results suggest that aquaporin expression in the osmoregulatory organs is mostly consistent between larvae that are developing in freshwater and brackish water. This suggests that aquaporins may not have major roles in adapting to longterm survival in brackish water or that aquaporin function may be regulated by other mechanisms like post-translational modifications.


Assuntos
Aedes/genética , Aquaporinas/genética , Osmorregulação/genética , Aedes/fisiologia , Animais , Aquaporinas/metabolismo , Infecções por Arbovirus , Transporte Biológico , Ecossistema , Água Doce , Expressão Gênica/genética , Regulação da Expressão Gênica/genética , Hemolinfa/metabolismo , Proteínas de Insetos/metabolismo , Larva/genética , Larva/metabolismo , Osmorregulação/fisiologia , Osmose , Águas Salinas , Salinidade , Água/metabolismo
3.
PLoS One ; 15(8): e0235930, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32750054

RESUMO

Circadian clocks control rhythms in physiology and behavior entrained to 24 h light-dark cycles. Despite of conserved general schemes, molecular circadian clockworks differ between insect species. With RNA interference (RNAi) we examined an ancient circadian clockwork in a basic insect, the hemimetabolous Madeira cockroach Rhyparobia maderae. With injections of double-stranded RNA (dsRNA) of cockroach period (Rm´per), timeless 1 (Rm´tim1), or cryptochrome 2 (Rm´cry2) we searched for essential components of the clock´s core negative feedback loop. Single injections of dsRNA of each clock gene into adult cockroaches successfully and permanently knocked down respective mRNA levels within ~two weeks deleting daytime-dependent mRNA rhythms for Rm´per and Rm´cry2. Rm´perRNAi or Rm´cry2RNAi affected total mRNA levels of both genes, while Rm´tim1 transcription was independent of both, also keeping rhythmic expression. Unexpectedly, circadian locomotor activity of most cockroaches remained rhythmic for each clock gene knockdown employed. It expressed weakened rhythms and unchanged periods for Rm´perRNAi and shorter periods for Rm´tim1RNAi and Rm´cry2RNAi.As a hypothesis of the cockroach´s molecular clockwork, a basic network of switched differential equations was developed to model the oscillatory behavior of clock cells expressing respective clock genes. Data were consistent with two synchronized main groups of coupled oscillator cells, a leading (morning) oscillator, or a lagging (evening) oscillator that couple via mutual inhibition. The morning oscillators express shorter, the evening oscillators longer endogenous periods based on core feedback loops with either PER, TIM1, or CRY2/PER complexes as dominant negative feedback of the clockwork. We hypothesize that dominant morning oscillator cells with shorter periods express PER, but not CRY2, or TIM1 as suppressor of clock gene expression, while two groups of evening oscillator cells with longer periods either comprise TIM1 or CRY2/PER suppressing complexes. Modelling suggests that there is an additional negative feedback next to Rm´PER in cockroach morning oscillator cells.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Baratas/fisiologia , Criptocromos/metabolismo , Proteínas de Insetos/metabolismo , Proteínas Circadianas Period/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Relógios Circadianos , Ritmo Circadiano , Baratas/genética , Criptocromos/genética , Proteínas de Insetos/genética , Masculino , Proteínas Circadianas Period/genética , Fotoperíodo , Interferência de RNA
4.
PLoS One ; 15(8): e0237744, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841246

RESUMO

Both the Mediterranean (MED) species of the Bemisia tabaci whitefly complex and the greenhouse whitefly (Trialeurodes vaporariorum, TV) are important agricultural pests. The two species of whiteflies differ in many aspects such as morphology, geographical distribution, host plant range, plant virus transmission, and resistance to insecticides. However, the molecular basis underlying their differences remains largely unknown. In this study, we analyzed the genetic divergences between the transcriptomes of MED and TV. In total, 2,944 pairs of orthologous genes were identified. The average identity of amino acid sequences between the two species is 93.6%. The average nonsynonymous (Ka) and synonymous (Ks) substitution rates and the ratio of Ka/Ks of the orthologous genes are 0.0389, 2.23 and 0.0204, respectively. The low average Ka/Ks ratio indicates that orthologous genes tend to be under strong purified selection. The most divergent gene classes are related to the metabolisms of xenobiotics, cofactors, vitamins and amino acids, and this divergence may underlie the different biological characteristics between the two species of whiteflies. Genes of differential expression between the two species are enriched in carbohydrate metabolism and regulation of autophagy. These findings provide molecular clues to uncover the biological and molecular differences between the two species of whiteflies.


Assuntos
Produção Agrícola , Genes de Insetos/genética , Especiação Genética , Hemípteros/genética , Proteínas de Insetos/genética , Sequência de Aminoácidos/genética , Substituição de Aminoácidos/genética , Aminoácidos/metabolismo , Animais , Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Região do Mediterrâneo , Anotação de Sequência Molecular , RNA-Seq , Homologia de Sequência de Aminoácidos , Especificidade da Espécie , Vitaminas/metabolismo , Xenobióticos/metabolismo
5.
PLoS One ; 15(8): e0235575, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745084

RESUMO

The sugarcane borer (Diatraea saccharalis, Fabricius, 1794) is a devastating pest that causes millions of dollars of losses each year to sugarcane producers by reducing sugar and ethanol yields. The control of this pest is difficult due to its endophytic behavior and rapid development. Pest management through biotechnological approaches has emerged in recent years as an alternative to currently applied methods. Genetic information about the target pests is often required to perform biotechnology-based management. The genomic and transcriptomic data for D. saccharalis are very limited. Herein, we report a tissue-specific transcriptome of D. saccharalis larvae and a differential expression analysis highlighting the physiological characteristics of this pest in response to two different diets: sugarcane and an artificial diet. Sequencing was performed on the Illumina HiSeq 2000 platform, and a de novo assembly was generated. A total of 27,626 protein-coding unigenes were identified, among which 1,934 sequences were differentially expressed between treatments. Processes such as defence, digestion, detoxification, signaling, and transport were highly represented among the differentially expressed genes (DEGs). Furthermore, seven aminopeptidase genes were identified as candidates to encode receptors of Cry proteins, which are toxins of Bacillus thuringiensis used to control lepidopteran pests. Since plant-insect interactions have produced a considerable number of adaptive responses in hosts and herbivorous insects, the success of phytophagous insects relies on their ability to overcome challenges such as the response to plant defences and the intake of nutrients. In this study, we identified metabolic pathways and specific genes involved in these processes. Thus, our data strongly contribute to the knowledge advancement of insect transcripts, which can be a source of target genes for pest management.


Assuntos
Dieta , Mucosa Intestinal/metabolismo , Lepidópteros/genética , Transcriptoma , Aminopeptidases/genética , Aminopeptidases/metabolismo , Animais , Herbivoria/genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Lepidópteros/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo
6.
PLoS Pathog ; 16(8): e1008754, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776975

RESUMO

Arbovirus infection of Aedes aegypti salivary glands (SGs) determines transmission. However, there is a dearth of knowledge on SG immunity. Here, we characterized SG immune response to dengue, Zika and chikungunya viruses using high-throughput transcriptomics. We also describe a transcriptomic response associated to apoptosis, blood-feeding and lipid metabolism. The three viruses differentially regulate components of Toll, Immune deficiency (IMD) and c-Jun N- terminal Kinase (JNK) pathways. However, silencing of the Toll and IMD pathway components showed variable effects on SG infection by each virus. In contrast, regulation of the JNK pathway produced consistent responses in both SGs and midgut. Infection by the three viruses increased with depletion of the activator Kayak and decreased with depletion of the negative regulator Puckered. Virus-induced JNK pathway regulates the complement factor, Thioester containing protein-20 (TEP20), and the apoptosis activator, Dronc, in SGs. Individual and co-silencing of these genes demonstrate their antiviral effects and that both may function together. Co-silencing either TEP20 or Dronc with Puckered annihilates JNK pathway antiviral effect. Upon infection in SGs, TEP20 induces antimicrobial peptides (AMPs), while Dronc is required for apoptosis independently of TEP20. In conclusion, we revealed the broad antiviral function of JNK pathway in SGs and showed that it is mediated by a TEP20 complement and Dronc-induced apoptosis response. These results expand our understanding of the immune arsenal that blocks arbovirus transmission.


Assuntos
Aedes/imunologia , Apoptose , Febre de Chikungunya/imunologia , Proteínas do Sistema Complemento/imunologia , Dengue/imunologia , Sistema de Sinalização das MAP Quinases , Glândulas Salivares/imunologia , Infecção por Zika virus/imunologia , Aedes/virologia , Animais , Febre de Chikungunya/metabolismo , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/virologia , Vírus Chikungunya/imunologia , Proteínas do Sistema Complemento/metabolismo , Dengue/metabolismo , Dengue/prevenção & controle , Dengue/virologia , Vírus da Dengue/imunologia , Feminino , Interações Hospedeiro-Patógeno , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Insetos Vetores/imunologia , Insetos Vetores/virologia , Glândulas Salivares/virologia , Transcriptoma , Replicação Viral , Zika virus/imunologia , Infecção por Zika virus/metabolismo , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/virologia
7.
PLoS One ; 15(8): e0237134, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764791

RESUMO

Olfaction plays vital roles in the survival and reproduction of insects. The completion of olfactory recognition requires the participation of various complex protein families. However, little is known about the olfactory-related proteins in Semiothisa cinerearia Bremer et Grey, an important pest of Chinese scholar tree. In this study, we sequenced the antennal transcriptome of S. cinerearia and identified 125 olfactory-related genes, including 25 odorant-binding proteins (OBPs), 15 chemosensory proteins (CSPs), two sensory neuron membrane proteins (SNMPs), 52 odorant receptors (ORs), eight gustatory receptors (GRs) and 23 ionotropic receptors (IRs). BLASTX best hit results and phylogenetic analyses indicated that these genes were most identical to their respective orthologs from Ectropis obliqua. Further quantitative real-time PCR (qRT-PCR) analysis revealed that three ScinOBPs and three ScinORs were highly expressed in male antennae, while seven ScinOBPs and twelve ScinORs were female-specifically expressed. Our study will be useful for the elucidation of olfactory mechanisms in S. cinerearia.


Assuntos
Antenas de Artrópodes/metabolismo , Proteínas de Insetos/metabolismo , Mariposas/fisiologia , Olfato/fisiologia , Animais , Antenas de Artrópodes/citologia , Feminino , Proteínas de Insetos/genética , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Odorantes , Neurônios Receptores Olfatórios/metabolismo , Filogenia , RNA-Seq , Receptores Ionotrópicos de Glutamato/genética , Receptores Ionotrópicos de Glutamato/metabolismo , Receptores Odorantes/genética , Receptores Odorantes/metabolismo
8.
PLoS Pathog ; 16(8): e1008697, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776976

RESUMO

The diamondback moth, Plutella xylostella, is a cosmopolitan pest and the first species to develop field resistance to toxins from the gram-positive bacterium Bacillus thuringiensis (Bt). Although previous work has suggested that mutations of ATP-binding cassette transporter subfamily C2 (ABCC2) or C3 (ABCC3) genes can confer Cry1Ac resistance, here we reveal that P. xylostella requires combined mutations in both PxABCC2 and PxABCC3 to achieve high-level Cry1Ac resistance, rather than simply a mutation of either gene. We identified natural mutations of PxABCC2 and PxABCC3 that concurrently occurred in a Cry1Ac-resistant strain (Cry1S1000) of P. xylostella, with a mutation (RA2) causing the mis-splicing of PxABCC2 and another mutation (RA3) leading to the premature termination of PxABCC3. Genetic linkage analysis showed that RA2 and RA3 were tightly linked to Cry1Ac resistance. Introgression of RA2 and RA3 enabled a susceptible strain (G88) of P. xylostella to obtain high resistance to Cry1Ac, confirming that these genes confer resistance. To further support the role of PxABCC2 and PxABCC3 in Cry1Ac resistance, frameshift mutations were introduced into PxABCC2 and PxABCC3 singly and in combination in the G88 strain with CRISPR/Cas9 mediated mutagenesis. Bioassays of CRISPR-based mutant strains, plus genetic complementation tests, demonstrated that the deletion of PxABCC2 or PxABCC3 alone provided < 4-fold tolerance to Cry1Ac, while disruption of both genes together conferred >8,000-fold resistance to Cry1Ac, suggesting the redundant/complementary roles of PxABCC2 and PxABCC3. This work advances our understanding of Bt resistance in P. xylostella by demonstrating mutations within both PxABCC2 and PxABCC3 genes are required for high-level Cry1Ac resistance.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/metabolismo , Resistência a Inseticidas , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/genética , Sequência de Aminoácidos , Animais , Bacillus thuringiensis , Proteínas de Insetos/química , Proteínas de Insetos/genética , Mariposas/química , Mariposas/genética , Mariposas/metabolismo , Mutação , Alinhamento de Sequência
9.
PLoS Pathog ; 16(8): e1008710, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32817722

RESUMO

Rice stripe virus (RSV, genus Tenuivirus, family Phenuiviridae) is the causal agent of rice stripe disease transmitted by the small brown planthopper (SBPH, Laodelphax striatellus) in a persistent propagative manner. The midgut and salivary glands of SBPH are the first and last barriers to the viral circulation and transmission processes, respectively; however, the precise mechanisms used by RSV to cross these organs and transmit to rice plants have not been fully elucidated. We obtained the full-length cDNA sequence of L. striatellus α-tubulin 2 (LsTUB) and found that RSV infection increased the level of LsTUB in vivo. Furthermore, LsTUB was shown to co-localize with RSV nonstructural protein 3 (NS3) in vivo and bound NS3 at positions 74-76 and 80-82 in vitro. Transient gene silencing of LsTUB expression caused a significant reduction in detectable RSV loads and viral NS3 expression levels, but had no effect on NS3 silencing suppressor activity and viral replication in insect cells. However, suppression of LsTUB attenuated viral spread in the bodies of SBPHs and decreased RSV transmission rates to rice plants. Electrical penetration graphs (EPG) showed that LsTUB knockdown by RNAi did not impact SBPH feeding; therefore, the reduction in RSV transmission rates was likely caused by a decrease in viral loads inside the planthopper. These findings suggest that LsTUB mediates the passage of RSV through midgut and salivary glands and leads to successful horizontal transmission.


Assuntos
Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Insetos Vetores/metabolismo , Oryza/virologia , Doenças das Plantas/virologia , Tenuivirus/fisiologia , Tubulina (Proteína)/metabolismo , Animais , Sistema Digestório/metabolismo , Sistema Digestório/virologia , Hemípteros/genética , Hemípteros/virologia , Proteínas de Insetos/genética , Insetos Vetores/genética , Insetos Vetores/virologia , Glândulas Salivares/metabolismo , Glândulas Salivares/virologia , Tubulina (Proteína)/genética
10.
Proc Natl Acad Sci U S A ; 117(28): 16283-16291, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32611810

RESUMO

The difficulty of achieving robust functional expression of insect nicotinic acetylcholine receptors (nAChRs) has hampered our understanding of these important molecular targets of globally deployed neonicotinoid insecticides at a time when concerns have grown regarding the toxicity of this chemotype to insect pollinators. We show that thioredoxin-related transmembrane protein 3 (TMX3) is essential to enable robust expression in Xenopus laevis oocytes of honeybee (Apis mellifera) and bumblebee (Bombus terrestris) as well as fruit fly (Drosophila melanogaster) nAChR heteromers targeted by neonicotinoids and not hitherto robustly expressed. This has enabled the characterization of picomolar target site actions of neonicotinoids, findings important in understanding their toxicity.


Assuntos
Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Neonicotinoides/farmacologia , Agonistas Nicotínicos/farmacologia , Receptores Nicotínicos/metabolismo , Acetilcolina/farmacologia , Animais , Abelhas/metabolismo , Relação Dose-Resposta a Droga , Drosophila melanogaster/metabolismo , Proteínas de Insetos/agonistas , Proteínas de Insetos/genética , Oócitos/metabolismo , Subunidades Proteicas/antagonistas & inibidores , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Receptores Nicotínicos/genética , Tiorredoxinas/genética , Tiorredoxinas/metabolismo , Xenopus laevis
11.
Proc Natl Acad Sci U S A ; 117(28): 16438-16447, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601213

RESUMO

Chemosensory communication is essential to insect biology, playing indispensable roles during mate-finding, foraging, and oviposition behaviors. These traits are particularly important during speciation, where chemical perception may serve to establish species barriers. However, identifying genes associated with such complex behavioral traits remains a significant challenge. Through a combination of transcriptomic and genomic approaches, we characterize the genetic architecture of chemoperception and the role of chemosensing during speciation for a young species pair of Heliconius butterflies, Heliconius melpomene and Heliconius cydno We provide a detailed description of chemosensory gene-expression profiles as they relate to sensory tissue (antennae, legs, and mouthparts), sex (male and female), and life stage (unmated and mated female butterflies). Our results untangle the potential role of chemical communication in establishing barriers during speciation and identify strong candidate genes for mate and host plant choice behaviors. Of the 252 chemosensory genes, HmOBP20 (involved in volatile detection) and HmGr56 (a putative synephrine-related receptor) emerge as strong candidates for divergence in pheromone detection and host plant discrimination, respectively. These two genes are not physically linked to wing-color pattern loci or other genomic regions associated with visual mate preference. Altogether, our results provide evidence for chemosensory divergence between H. melpomene and H. cydno, two rarely hybridizing butterflies with distinct mate and host plant preferences, a finding that supports a polygenic architecture of species boundaries.


Assuntos
Borboletas/genética , Evolução Molecular , Especiação Genética , Proteínas de Insetos/genética , Animais , Borboletas/classificação , Borboletas/fisiologia , Quimiotaxia , Feminino , Proteínas de Insetos/metabolismo , Masculino , Fenótipo , Sensação
12.
Gene ; 760: 144998, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32717304

RESUMO

The life cycle of holometabolous insects involves different stages and cathepsin plays an important role in insect metamorphosis. In the present study, we investigated the function of Bombyx mori cathepsin-L (Bm-CatL) during metamorphosis and analyzed their role in programmed cell death (PCD) of the fat body. The results showed that knockdown of Bm-CatL by RNA interference led to abnormal pupation and a delay in fat body degradation during metamorphosis. Furthermore, PCD inhibition was observed in the fat body after downregulation of Bm-CatL. To confirm this finding, PCD was induced in Bombyx mori embryonic (BmE) cells by ultraviolet ray irradiation. We found that the PCD of BmE cells was weakened after knocking down Bm-CatL. Moreover, overexpression of Bm-CatL in cells promoted PCD. Overall, our results showed that Bm-CatL is involved in the degradation of internal tissues and promotes the PCD of cells involved in the pupation of silkworms. Thus, this study provides us with a better understanding for function of cathepsin-L during metamorphosis.


Assuntos
Bombyx/fisiologia , Catepsina L/metabolismo , Tecido Adiposo/metabolismo , Animais , Apoptose/fisiologia , Bombyx/genética , Bombyx/metabolismo , Corpo Adiposo/metabolismo , Proteínas de Insetos/metabolismo , Metamorfose Biológica , Interferência de RNA
13.
Proc Natl Acad Sci U S A ; 117(29): 16928-16937, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32636269

RESUMO

Whereas most of the arthropod-borne animal viruses replicate in their vectors, this is less common for plant viruses. So far, only some plant RNA viruses have been demonstrated to replicate in insect vectors and plant hosts. How plant viruses evolved to replicate in the animal kingdom remains largely unknown. Geminiviruses comprise a large family of plant-infecting, single-stranded DNA viruses that cause serious crop losses worldwide. Here, we report evidence and insight into the replication of the geminivirus tomato yellow leaf curl virus (TYLCV) in the whitefly (Bemisia tabaci) vector and that replication is mainly in the salivary glands. We found that TYLCV induces DNA synthesis machinery, proliferating cell nuclear antigen (PCNA) and DNA polymerase δ (Polδ), to establish a replication-competent environment in whiteflies. TYLCV replication-associated protein (Rep) interacts with whitefly PCNA, which recruits DNA Polδ for virus replication. In contrast, another geminivirus, papaya leaf curl China virus (PaLCuCNV), does not replicate in the whitefly vector. PaLCuCNV does not induce DNA-synthesis machinery, and the Rep does not interact with whitefly PCNA. Our findings reveal important mechanisms by which a plant DNA virus replicates across the kingdom barrier in an insect and may help to explain the global spread of this devastating pathogen.


Assuntos
Begomovirus/fisiologia , DNA Polimerase III/metabolismo , Hemípteros/virologia , Proteínas de Insetos/metabolismo , Insetos Vetores/virologia , Replicação Viral , Animais , Begomovirus/genética , DNA Polimerase III/genética , Gossypium/parasitologia , Gossypium/virologia , Hemípteros/patogenicidade , Interações Hospedeiro-Patógeno , Proteínas de Insetos/genética , Insetos Vetores/patogenicidade , Glândulas Salivares/metabolismo , Glândulas Salivares/virologia
14.
PLoS One ; 15(7): e0228835, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649665

RESUMO

The mosquito Culex erythrothorax Dyar is a West Nile virus (WNV) vector that breeds in wetlands with emergent vegetation. Urbanization and recreational activities near wetlands place humans, birds and mosquitoes in close proximity, increasing the risk of WNV transmission. Adult Cx. erythrothorax abundance peaked in a wetland bordering the San Francisco Bay of California (USA) during the first 3 hours after sunset (5527 ± 4070 mosquitoes / trap night) while peak adult Culex tarsalis Coquillett abundance occurred during the subsequent 3 h period (83 ± 30 Cx. tarsalis). When insecticide resistance was assessed using bottle bioassay, Cx. erythrothorax was highly sensitive to permethrin, naled, and etofenprox insecticides compared to a strain of Culex pipiens that is susceptible to insecticides (LC50 = 0.35, 0.71, and 4.1 µg/bottle, respectively). The Cx. erythrothorax were 2.8-fold more resistant to resmethrin, however, the LC50 value was low (0.68 µg/bottle). Piperonyl butoxide increased the toxicity of permethrin (0.5 µg/bottle) and reduced knock down time, but a higher permethrin concentration (2.0 µg/bottle) did not have similar effects. Bulk mixed-function oxidase, alpha-esterase, or beta-esterase activities in mosquito homogenates were higher in Cx. erythrothorax relative to the Cx. pipiens susceptible strain. There was no difference in the activity of glutathione S-transferase between the two mosquito species and insensitive acetylcholine esterase was not detected. Larvicides that were applied to the site had limited impact on reducing mosquito abundance. Subsequent removal of emergent vegetation in concert with larvicide applications and reduced daily environmental temperature substantially reduced mosquito abundance. To control Cx. erythrothorax in wetlands, land managers should consider vegetation removal so that larvicide can efficiently enter the water. Vector control agencies may more successfully control adult viremic Cx. erythrothorax that enter nearby neighborhoods by applying adulticides during the 3 h that follow sunset.


Assuntos
Culex/fisiologia , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/toxicidade , Animais , California , Culex/crescimento & desenvolvimento , Esterases/metabolismo , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Controle de Mosquitos , Permetrina/toxicidade , Butóxido de Piperonila/química , Piretrinas/toxicidade , Áreas Alagadas
15.
Proc Natl Acad Sci U S A ; 117(32): 19209-19220, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32723826

RESUMO

Some organisms have evolved a survival strategy to withstand severe dehydration in an ametabolic state, called anhydrobiosis. The only known example of anhydrobiosis among insects is observed in larvae of the chironomid Polypedilum vanderplanki Recent studies have led to a better understanding of the molecular mechanisms underlying anhydrobiosis and the action of specific protective proteins. However, gene regulation alone cannot explain the rapid biochemical reactions and independent metabolic changes that are expected to sustain anhydrobiosis. For this reason, we conducted a comprehensive comparative metabolome-transcriptome analysis in the larvae. We showed that anhydrobiotic larvae adopt a unique metabolic strategy to cope with complete desiccation and, in particular, to allow recovery after rehydration. We argue that trehalose, previously known for its anhydroprotective properties, plays additional vital roles, providing both the principal source of energy and also the restoration of antioxidant potential via the pentose phosphate pathway during the early stages of rehydration. Thus, larval viability might be directly dependent on the total amount of carbohydrate (glycogen and trehalose). Furthermore, in the anhydrobiotic state, energy is stored as accumulated citrate and adenosine monophosphate, allowing rapid reactivation of the citric acid cycle and mitochondrial activity immediately after rehydration, before glycolysis is fully functional. Other specific adaptations to desiccation include potential antioxidants (e.g., ophthalmic acid) and measures to avoid the accumulation of toxic waste metabolites by converting these to stable and inert counterparts (e.g., xanthurenic acid and allantoin). Finally, we confirmed that these metabolic adaptations correlate with unique organization and expression of the corresponding enzyme genes.


Assuntos
Dípteros/metabolismo , Proteínas de Insetos/metabolismo , Monofosfato de Adenosina/metabolismo , Animais , Dessecação , Dípteros/química , Dípteros/genética , Secas , Glicogênio/genética , Glicogênio/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/genética , Larva/química , Larva/genética , Larva/metabolismo , Metaboloma , Transcriptoma , Trealose/metabolismo , Água/metabolismo
16.
PLoS One ; 15(6): e0234137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497152

RESUMO

The aim of this study was to determine the effect of rotenone stress on Aphis glycines Matsumura (Hemiptera: Aphididae) populations in different habitats of Northeast China. The changes in kinase expression activity of endogenous substances (proteins, total sugars, trehalose, cholesterol, and free amino acids), detoxifying enzymes (cytochrome P450 and glutathione S-transferase), and metabolic enzymes (proteases and phosphofructokinases) in specimens from three populations were compared before and after stress with rotenone at median lethal concentration (LC50) and their response mechanisms were analyzed. Following a 24 h treatment with rotenone, the average LC50 rotenone values in A. glycines specimens from field populations A and B, and a laboratory population were 4.39, 4.61, and 4.03 mg/L, respectively. The degree of changes in the kinase expression activity of endogenous substances also differed, which indicated a difference in the response of A. glycines specimens from varying habitats to LC50 rotenone stress. The content of endogenous substances, detoxifying enzymes, and metabolic enzymes, except for that of free amino acids, changed significantly in all populations treated with rotenone at LC50 compared with that in the control (P < 0.05). The decrease in protein and trehalose content, and the obstruction of cholesterol transportation owing to decreased feeding in stressed individuals were the causes of A. glycines death after rotenone treatment. Aphis glycines resistance to rotenone may be related to cytochrome P450 expression.


Assuntos
Afídeos/efeitos dos fármacos , Afídeos/fisiologia , Rotenona/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Animais , Afídeos/metabolismo , Colesterol/metabolismo , Ecossistema , Proteínas de Insetos/metabolismo , Trealose/metabolismo
17.
Nat Commun ; 11(1): 3003, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32532972

RESUMO

The arms race between entomopathogenic bacteria and their insect hosts is an excellent model for decoding the intricate coevolutionary processes of host-pathogen interaction. Here, we demonstrate that the MAPK signaling pathway is a general switch to trans-regulate differential expression of aminopeptidase N and other midgut genes in an insect host, diamondback moth (Plutella xylostella), thereby countering the virulence effect of Bacillus thuringiensis (Bt) toxins. Moreover, the MAPK cascade is activated and fine-tuned by the crosstalk between two major insect hormones, 20-hydroxyecdysone (20E) and juvenile hormone (JH) to elicit an important physiological response (i.e. Bt resistance) without incurring the significant fitness costs often associated with pathogen resistance. Hormones are well known to orchestrate physiological trade-offs in a wide variety of organisms, and our work decodes a hitherto undescribed function of these classic hormones and suggests that hormonal signaling plasticity is a general cross-kingdom strategy to fend off pathogens.


Assuntos
Bacillus thuringiensis/metabolismo , Toxinas Bacterianas/metabolismo , Hormônios de Inseto/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Mariposas/metabolismo , Transdução de Sinais , Animais , Bacillus thuringiensis/fisiologia , Proteínas de Bactérias/metabolismo , Antígenos CD13/classificação , Antígenos CD13/genética , Antígenos CD13/metabolismo , Endotoxinas/metabolismo , Regulação da Expressão Gênica , Proteínas Hemolisinas/metabolismo , Interações Hospedeiro-Patógeno , Proteínas de Insetos/classificação , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Mariposas/genética , Mariposas/microbiologia , Filogenia , Células Sf9 , Spodoptera
18.
PLoS Genet ; 16(5): e1008772, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32365064

RESUMO

In the postgenomics era, comparative genomics have advanced the understanding of evolutionary processes of neuropeptidergic signaling systems. The evolutionary origin of many neuropeptidergic signaling systems can be traced date back to early metazoan evolution based on the conserved sequences. Insect parathyroid hormone receptor (iPTHR) was previously described as an ortholog of vertebrate PTHR that has a well-known function in controlling bone remodeling. However, there was no sequence homologous to PTH sequence in insect genomes, leaving the iPTHR as an orphan receptor. Here, we identified the authentic ligand insect PTH (iPTH) for the iPTHR. The taxonomic distribution of iPTHR, which is lacking in Diptera and Lepidoptera, provided a lead for identifying the authentic ligand. We found that a previously described orphan ligand known as PXXXamide (where X is any amino acid) described in the cuttlefish Sepia officinalis has a similar taxonomic distribution pattern as iPTHR. Tests of this peptide, iPTH, in functional reporter assays confirmed the interaction of the ligand-receptor pair. Study of a model beetle, Tribolium castaneum, was used to investigate the function of the iPTH signaling system by RNA interference followed by RNA sequencing and phenotyping. The results suggested that the iPTH system is likely involved in the regulation of cuticle formation that culminates with a phenotype of defects in wing exoskeleton maturation at the time of adult eclosion. Moreover, RNAi of iPTHRs also led to significant reductions in egg numbers and hatching rates after parental RNAi.


Assuntos
Neuropeptídeos/metabolismo , Hormônio Paratireóideo/metabolismo , Receptores de Hormônios Paratireóideos/genética , Tribolium/anatomia & histologia , Animais , Evolução Molecular , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Fenótipo , Filogenia , Receptores de Hormônios Paratireóideos/metabolismo , Análise de Sequência de RNA , Tribolium/genética , Tribolium/metabolismo , Asas de Animais/anatomia & histologia
19.
Nat Commun ; 11(1): 2205, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371874

RESUMO

Flaviviruses, including Zika virus (ZIKV), utilise host mRNA degradation machinery to produce subgenomic flaviviral RNA (sfRNA). In mammalian hosts, this noncoding RNA facilitates replication and pathogenesis of flaviviruses by inhibiting IFN-signalling, whereas the function of sfRNA in mosquitoes remains largely elusive. Herein, we conduct a series of in vitro and in vivo experiments to define the role of ZIKV sfRNA in infected Aedes aegypti employing viruses deficient in production of sfRNA. We show that sfRNA-deficient viruses have reduced ability to disseminate and reach saliva, thus implicating the role for sfRNA in productive infection and transmission. We also demonstrate that production of sfRNA alters the expression of mosquito genes related to cell death pathways, and prevents apoptosis in mosquito tissues. Inhibition of apoptosis restored replication and transmission of sfRNA-deficient mutants. Hence, we propose anti-apoptotic activity of sfRNA as the mechanism defining its role in ZIKV transmission.


Assuntos
Aedes/genética , Apoptose/genética , Mosquitos Vetores/genética , RNA Viral/genética , Infecção por Zika virus/genética , Zika virus/genética , Aedes/citologia , Aedes/virologia , Animais , Células Cultivadas , Chlorocebus aethiops , Regulação da Expressão Gênica , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Mosquitos Vetores/citologia , Mosquitos Vetores/virologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA não Traduzido/genética , RNA não Traduzido/metabolismo , RNA Viral/metabolismo , Células Vero , Replicação Viral/genética , Zika virus/fisiologia , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
20.
PLoS One ; 15(5): e0233033, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437365

RESUMO

Pesticide exposures can have detrimental impacts on bee pollinators, ranging from immediate mortality to sub-lethal impacts. Flupyradifurone is the active ingredient in Sivanto™ and sulfoxaflor is the active ingredient in Transform®. They are both relatively new insecticides developed with an intent to reduce negative effects on bees, when applied to bee-attractive crops. With the growing concern regarding pollinator health and pollinator declines, it is important to have a better understanding of any potential negative impacts, especially sub-lethal, of these pesticides on bees. This study reports novel findings regarding physiological stress experienced by bees exposed to field application rates of these two insecticides via a Potter Tower sprayer. Two contact exposure experiments were conducted-a shorter 6-hour study and a longer 10-day study. Honey bee mortality, sugar syrup and water consumption, and physiological responses (oxidative stress and apoptotic protein assays) were assessed in bees exposed to Sivanto™ and Transform®, and compared to bees in control group. For the longer, 10-day contact exposure experiment, only the Sivanto™ group was compared to the control group, as high mortality recorded in the sulfoxaflor treatment group during the shorter contact exposure experiment, made the latter group unfeasible to test in the longer 10-days experiment. In both the studies, sugar syrup and water consumptions were significantly different between treatment groups and controls. The highest mortality was observed in Transform® exposed bees, followed by the Sivanto™ exposed bees. Estimates of reactive oxygen/nitrogen species indicated significantly elevated oxidative stress in both pesticide treatment groups, when compared to controls. Caspase-3 protein assays, an indicator of onset of apoptosis, was also significantly higher in the pesticide treatment groups. These differences were largely driven by post exposure duration, indicating sub-lethal impacts. Further, our findings also emphasize the need to revisit contact exposure impacts of Sivanto™, given the sub-lethal impacts and mortality observed in our long-term (10-day) contact exposure experiment.


Assuntos
4-Butirolactona/análogos & derivados , Abelhas/efeitos dos fármacos , Praguicidas/efeitos adversos , Piridinas/efeitos adversos , Compostos de Enxofre/efeitos adversos , 4-Butirolactona/efeitos adversos , Animais , Abelhas/metabolismo , Caspase 3/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Proteínas de Insetos/metabolismo , Estresse Oxidativo , Polinização , Fatores de Tempo
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