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‣ INSECT CHYMOTRYPSINS: CHLOROMETHYL KETONE INACTIVATION AND SUBSTRATE SPECIFICITY RELATIVE TO POSSIBLE COEVOLUTIONAL ADAPTATION OF INSECTS AND PLANTS

LOPES, Adriana R.; SARO, Poloma M.; TERRA, Walter R.
Fonte: WILEY-LISS Publicador: WILEY-LISS
Tipo: Artigo de Revista Científica
Português
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Insect digestive chymotrypsins are present in a large variety of insect orders but their substrate specificity still remains unclear. Ewer insect chymotrypsins from 3 different insect orders (Dictyoptera, Coleoptera and two Lepidoptera) were isolated using affinity chromatography. Enzymes presented molecular masses in the range of 20 to 31 kDa and pH optima in the range of 7.5 to 10.0. Kinetic characterization. using different, colorimetric and fluorescent substrates indicated that insect chymotrypsins differ from, bovine chymotrypsin in their primary specificity toward small substrates (like N-benzoyl-L-Tyr p-nitroanilide) rather than on their preference for large substrates (exemplified by Succynil-Ala-Ala-Pro-Phe P-nitroanilide). Chloromethyl ketones (TPCK, N-alpha-tosyl-L-Phe chloromethyl ketone and Z-GGF-CK, N-carbobenzoxy-Gly-Gly-phe-CK) inactivated all chymotrypsins legated. Inactivation rates follow apparent first-order kinetics with variable second order rates (TPCK, 42 to 130 M(-1)s(-1); Z-GGF-CK, 150 to 450 M(-1)s(-1) that may be remarkably low for S. frugiperda chymotrypsin (TPCK, 6 M(-1)s(-1); Z-GGF-CK, 6.1 M(-1) s(-1)). Homology modelling and sequence alignment showed that. in lepidopteran chymotrypsins, differences in the amino acid residues in the neighborhood of the catalytic His 57 may affect its pKa...

‣ Signal classification by similarity and feature extraction allows an important application in insect recognition

Silva, Diego Furtado; Batista, Gustavo Enrique de Almeida Prado Alves
Fonte: Universidade de São Paulo - USP; Universidade Federal de São Carlos - UFSCar; Centro de Robótica de São Carlos - CROB; Sociedade Brasileira de Computação - SBC; Sociedade Brasileira de Automática – SBA; São Carlos Publicador: Universidade de São Paulo - USP; Universidade Federal de São Carlos - UFSCar; Centro de Robótica de São Carlos - CROB; Sociedade Brasileira de Computação - SBC; Sociedade Brasileira de Automática – SBA; São Carlos
Tipo: Conferência ou Objeto de Conferência
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Insects have a strong relationship with the humanity, in both positive and negative ways. It is estimated that insects, particularly bees, pollinate at least twothirds of all food consumed in the world. In contrast, mosquito borne diseases kill millions of people every year. Due to such a complex relationship, insect control attempts must be carefully planned. Otherwise, there is the risk of eliminating beneficial species, such as the recent threat of bee extinction. We are developing a novel sensor as a tool to control disease vectors and agricultural pests. This sensor captures insect flight information using laser light and classify the insects according to their species. Therefore, the sensor will provide real-time population estimates of species. Such information is the key to enable effective alarming systems for outbreaks, the intelligent use of insect control techniques, such as insecticides, and will be the heart of the next generation of insect traps that will capture only species of interest. In this paper, we demonstrate how we overtook the most importante challenge to make this sensor practical: the creation of accurate classification systems. The sensor generates a very brief signal as result of the instant that the insect crosses the laser. Such events last for tenths of a second and have a very simple structure...

‣ Comunidade bacteriana associada às cigarrinhas (Hemiptera:Cicadellidae), insetos vetores de Xylella fastidiosa; Bacterial community associated to sharpshooters (Hemiptera: Cicadellidae) insect vectors of Xylella fastidiosa

Gai, Cláudia Santos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/12/2006 Português
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A Clorose Variegada dos Citros (CVC), doença que causa graves prejuízos à citricultura no estado de São Paulo, é causada pela bactéria Xylella fastidiosa que é transmitida pelas cigarrinhas Bucephalogonia xanthophis (Berg), Dilobopterus costalimai (Young), Acrogonia citrina (Marucci & Cavichioli) e Oncometopia facialis (Signoret). Durante a alimentação em plantas afetadas, esses insetos adquirem a bactéria, que coloniza o pré-cibário e o cibário, e depois são capazes de transmitir a doença para plantas sadias. Colonizando o xilema das plantas de citros encontram-se também bactérias endofíticas, que são microrganismos capazes de colonizar internamente tecidos de plantas sem causar dano aparente, e que podem interagir com patógenos no interior do hospedeiro. Este trabalho teve como objetivo avaliar a comunidade bacteriana associada as cigarrinhas vetoras de CVC, e observar as possíveis interações que ocorrem entre insetos vetores de X. fastidiosa e bactérias endofíticas de citros. Primeiramente foi feito um isolamento das bactérias da cabeça de cigarrinhas coletadas em pomares de citros afetados com CVC. Foram isoladas um total de 17230 bactérias de três espécies de cigarrinhas (O. facialis, D. costalimai e A. citrina) em três datas diferentes (22/março...

‣ Criação massal em dieta líquida e radioesterilização da mosca-sul-americana Anastrepha sp.1 aff. fraterculus (Wied., 1830) (Diptera: Tephritidae); Mass production in liquid diet and radioesterilização of South American fruit fly Anastrepha sp.1 aff. fraterculus (Wied., 1830) (Díptera: Tephritidae)

Kamiya, Aline Cristiane
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/10/2010 Português
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Tanto as técnicas de controle biológico quanto a Técnica do inseto estéril (TIE), são utilizadas em vários países para o controle, supressão e até mesmo erradicação de moscas-das-frutas e outras pragas da agricultura, pecuária e saúde publica. O uso de tais técnicas minimiza o emprego contínuo de inseticidas, protege o ambiente e se adequa aos padrões de segurança alimentar. No entanto, é necessário para a implementação de tais programas, tecnologia para produzir milhões de parasitóides e a própria praga em laboratório com qualidade biológica similar aos insetos encontrados na natureza e com custo competitivo com o controle químico. Os objetivos deste trabalho foi estabelecer protocolos para criação artificial de A. sp. 1 aff. fraterculus em dieta larval líquida que permita atingir níveis de criação massal, para uma possível diminuição no custo da criação e determinar a dose de radiação esterilizante para adultos de A. sp. 1 aff. fraterculus atendendo os parâmetros de qualidade exigidos pela Técnica do Inseto Estéril com insetos provenientes da criação do Laboratório de Radioentomologia do CENA/USP. Foram testadas sete dietas em relação à dieta convencional utilizada no laboratório de Radioentomologia do CENA/USP...

‣ Comunidades de insetos de sub-bosque em diferentes fisionomias vegetais

Troian, Vera Regina Ribeiro
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
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A conversão de áreas de vegetação nativa em monoculturas florestais tem sido uma prática bastante empregada no Sul do Brasil. No estado do Rio Grande do Sul, a região dos Campos de Cima da Serra tem tido sua paisagem original modificada por esta prática, principalmente nas últimas décadas. Muitos organismos são bons indicadores deste tipo de alteração ambiental, dentre eles os artrópodos. Os insetos são adequados para uso em estudos de avaliação de impacto ambiental e de efeitos de fragmentação florestal, pois, além de ser o grupo animal mais numeroso, com elevadas densidades populacionais, também apresentam grande diversidade, em termos de espécies e de habitats. Nosso estudo teve como objetivos avaliar a influência dos subbosques de diferentes fisionomias vegetais de uma Floresta Ombrófila Mista manejada do Sul do Brasil sobre a comunidade de insetos deste sub-bosque; bem como verificar se a estrutura do habitat dessas fisionomias vegetais pode influenciar os padrões da comunidade entomológica. Investigamos se a abundância, a riqueza e a composição da comunidade de insetos modificaram-se de acordo com a fisionomia vegetal. Também foi nosso objetivo avaliar se as diferentes fisionomias vegetais dessa Floresta e as suas estruturas do habitat estão relacionadas com a estrutura trófica da comunidade de coleópteros de sub-bosque. Foram comparados quatro ambientes florestais distintos: áreas de floresta com Araucaria (FA)...

‣ Insect sodium channels and insecticide resistance

Dong, Ke
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Voltage-gated sodium channels are essential for the generation and propagation of action potentials (i.e., electrical impulses) in excitable cells. Although most of our knowledge about sodium channels is derived from decades of studies of mammalian isoforms, research on insect sodium channels is revealing both common and unique aspects of sodium channel biology. In particular, our understanding of the molecular dynamics and pharmacology of insect sodium channels has advanced greatly in recent years, thanks to successful functional expression of insect sodium channels in Xenopus oocytes and intensive efforts to elucidate the molecular basis of insect resistance to insecticides that target sodium channels. In this review, I discuss recent literature on insect sodium channels with emphases on the prominent role of alternative splicing and RNA editing in the generation of functionally diverse sodium channels in insects and the current understanding of the interactions between insect sodium channels and insecticides.

‣ The MrCYP52 Cytochrome P450 Monoxygenase Gene of Metarhizium robertsii Is Important for Utilizing Insect Epicuticular Hydrocarbons

Lin, Liangcai; Fang, Weiguo; Liao, Xinggang; Wang, Fengqing; Wei, Dongzhi; St. Leger, Raymond J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 16/12/2011 Português
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Fungal pathogens of plants and insects infect their hosts by direct penetration of the cuticle. Plant and insect cuticles are covered by a hydrocarbon-rich waxy outer layer that represents the first barrier against infection. However, the fungal genes that underlie insect waxy layer degradation have received little attention. Here we characterize the single cytochrome P450 monoxygenase family 52 (MrCYP52) gene of the insect pathogen Metarhizium robertsii, and demonstrate that it encodes an enzyme required for efficient utilization of host hydrocarbons. Expressing a green florescent protein gene under control of the MrCYP52 promoter confirmed that MrCYP52 is up regulated on insect cuticle as well as by artificial media containing decane (C10), extracted cuticle hydrocarbons, and to a lesser extent long chain alkanes. Disrupting MrCYP52 resulted in reduced growth on epicuticular hydrocarbons and delayed developmental processes on insect cuticle, including germination and production of appressoria (infection structures). Extraction of alkanes from cuticle prevented induction of MrCYP52 and reduced growth. Insect bioassays against caterpillars (Galleria mellonella) confirmed that disruption of MrCYP52 significantly reduces virulence. However...

‣ Prostaglandins and Their Receptors in Insect Biology

Stanley, David; Kim, Yonggyun
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 30/12/2011 Português
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We treat the biological significance of prostaglandins (PGs) and their known receptors in insect biology. PGs and related eicosanoids are oxygenated derivatives of arachidonic acid (AA) and two other C20 polyunsaturated fatty acids. PGs are mostly appreciated in the context of biomedicine, but a growing body of literature indicates the biological significance of these compounds extends throughout the animal kingdom, and possibly beyond. The actions of most PGs are mediated by specific receptors. Biomedical research has discovered a great deal of knowledge about PG receptors in mammals, including their structures, pharmacology, molecular biology and cellular locations. Studies of PG receptors in insects lag behind the biomedical background, however, recent results hold the promise of accelerated research in this area. A PG receptor has been identified in a class of lepidopteran hemocytes and experimentally linked to the release of prophenoloxidase. PGs act in several crucial areas of insect biology. In reproduction, a specific PG, PGE2, releases oviposition behavior in most crickets and a few other insect species; PGs also mediate events in egg development in some species, which may represent all insects. PGs play major roles in modulating fluid secretion in Malpighian tubules...

‣ Molecular Cloning and Functional Characterization of a Lepidopteran Insect β4-N-Acetylgalactosaminyltransferase with Broad Substrate Specificity, a Functional Role in Glycoprotein Biosynthesis, and a Potential Functional Role in Glycolipid Biosynthesis*

Vadaie, Nadia; Jarvis, Donald L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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A degenerate PCR approach was used to isolate a lepidopteran insect cDNA encoding a β4-galactosyltransferase family member. The isolation and initial identification of this cDNA was based on bioinformatics, but its identification as a β4-galactosyltransferase family member was experimentally confirmed. The newly identified β4-galactosyltransferase family member had unusually broad donor and acceptor substrate specificities in vitro, as transfered galactose, N-acetylglucosamine, and N-acetylgalactosamine to carbohydrate, glycoprotein, and glycolipid acceptors. However, the enzyme preferentially utilized N-acetylgalactosamine as the donor for all three acceptors, and its derived amino acid sequence was closely related to a known N-acetylgalactosaminyltransferase. These data suggested that the newly isolated cDNA encodes a β4-N-acetylgalactosaminyltransferase that functions in insect cell glycoprotein biosynthesis, glycolipid biosynthesis, or both. The remainder of this study focused on the role of this enzyme in N-glycoprotein biosynthesis. The results showed that the purified enzyme transferred N-acetylgalactosamine, but no detectable galactose or N-acetylglucosamine, to a synthetic N-glycan in vitro. The structure of the reaction product was confirmed by chromatographic...

‣ Utility of temporally distinct baculovirus promoters for constitutive and baculovirus-inducible transgene expression in transformed insect cells

Lin, Chi-Hung; Jarvis, Donald L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Genetically transformed lepidopteran insect cell lines have biotechnological applications as constitutive recombinant protein production platforms and improved hosts for baculovirus-mediated recombinant protein production. Insect cell transformation is often accomplished with a DNA construct(s) encoding a foreign protein(s) under the transcriptional control of a baculovirus immediate early promoter, such as the ie1 promoter. However, the potential utility of increasingly stronger promoters from later baculovirus gene classes, such as delayed early (39K), late (p6.9), and very late (polh), has not been systematically assessed. Hence, we produced DNA constructs encoding secreted alkaline phosphatase (SEAP) under the transcriptional control of each of the four temporally distinct classes of baculovirus promoters, used them to transform insect cells, and compared the levels of SEAP RNA and protein production obtained before and after baculovirus infection. The ie1 construct was the only one that supported SEAP protein production by transformed insect cells prior to baculovirus infection, confirming that only immediate early promoters can be used to isolate transformed insect cells for constitutive recombinant protein production. However...

‣ Microbial Brokers of Insect-Plant Interactions Revisited

Douglas, Angela E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Recent advances in sequencing methods have transformed the field of microbial ecology, making it possible to determine the composition and functional capabilities of uncultured microorganisms. These technologies have been instrumental in the recognition that resident microorganisms can have profound effects on the phenotype and fitness of their animal hosts by modulating the animal signaling networks that regulate growth, development, behavior, etc. Against this backdrop, this review assesses the impact of microorganisms on insect-plant interactions, in the context of the hypothesis that microorganisms are biochemical brokers of plant utilization by insects. There is now overwhelming evidence for a microbial role in insect utilization of certain plant diets with an extremely low or unbalanced nutrient content. Specifically, microorganisms enable insect utilization of plant sap by synthesizing essential amino acids. They also can broker insect utilization of plant products of extremely high lignocellulose content, by enzymatic breakdown of complex plant polysaccharides, nitrogen fixation, and sterol synthesis. However, the experimental evidence for microbial-mediated detoxification of plant allelochemicals is limited. The significance of microorganisms as brokers of plant utilization by insects is predicted to vary...

‣ A New theraphosid Spider Toxin Causes Early Insect Cell Death by Necrosis When Expressed In Vitro during Recombinant Baculovirus Infection

Ardisson-Araújo, Daniel Mendes Pereira; Morgado, Fabrício Da Silva; Schwartz, Elisabeth Ferroni; Corzo, Gerardo; Ribeiro, Bergmann Morais
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 13/12/2013 Português
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Baculoviruses are the most studied insect viruses in the world and are used for biological control of agricultural and forest insect pests. They are also used as versatile vectors for expression of heterologous proteins. One of the major problems of their use as biopesticides is their slow speed to kill insects. Thus, to address this shortcoming, insect-specific neurotoxins from arachnids have been introduced into the baculovirus genome solely aiming to improve its virulence. In this work, an insecticide-like toxin gene was obtained from a cDNA derived from the venom glands of the theraphosid spider Brachypelma albiceps. The mature form of the peptide toxin (called Ba3) has a high content of basic amino acid residues, potential for three possible disulfide bonds, and a predicted three-stranded β-sheetDifferent constructions of the gene were engineered for recombinant baculovirus Autographa californica multiple nuclepolyhedrovirus (AcMNPV) expression. Five different forms of Ba3 were assessed; (1) the full-length sequence, (2) the pro-peptide and mature region, (3) only the mature region, and the mature region fused to an (4) insect or a (5) virus-derived signal peptide were inserted separately into the genome of the baculovirus. All the recombinant viruses induced cell death by necrosis earlier in infection relative to a control virus lacking the toxin gene. However...

‣ Insect prophenoloxidase: the view beyond immunity

Lu, Anrui; Zhang, Qiaoli; Zhang, Jie; Yang, Bing; Wu, Kai; Xie, Wei; Luan, Yun-Xia; Ling, Erjun
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 11/07/2014 Português
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Insect prophenoloxidase (PPO) is an important innate immunity protein due to its involvement in cellular and humoral defense. It belongs to a group of type-3 copper-containing proteins that occurs in almost all organisms. Insect PPO has been studied for over a century, and the PPO activation cascade is becoming clearer. The insect PPO activation pathway incorporates several important proteins, including pattern-recognition receptors (PGRP, β GRP, and C-type lectins), serine proteases, and serine protease inhibitors (serpins). Due to their complexity, PPO activation mechanisms vary among insect species. Activated phenoloxidase (PO) oxidizes phenolic molecules to produce melanin around invading pathogens and wounds. The crystal structure of Manduca sexta PPO shows that a conserved amino acid, phenylalanine (F), can block the active site pocket. During activation, this blocker must be dislodged or even cleaved at the N-terminal sequence to expose the active site pockets and allow substrates to enter. Thanks to the crystal structure of M. sexta PPO, some domains and specific amino acids that affect PPO activities have been identified. Further studies of the relationship between PPO structure and enzyme activities will provide an opportunity to examine other type-3 copper proteins...

‣ Competition with wind-pollinated plant species alters floral traits of insect-pollinated plant species

Flacher, Floriane; Raynaud, Xavier; Hansart, Amandine; Motard, Eric; Dajoz, Isabelle
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 03/09/2015 Português
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Plant traits related to attractiveness to pollinators (e.g. flowers and nectar) can be sensitive to abiotic or biotic conditions. Soil nutrient availability, as well as interactions among insect-pollinated plants species, can induce changes in flower and nectar production. However, further investigations are needed to determine the impact of interactions between insect-pollinated species and abiotically pollinated species on such floral traits, especially floral rewards. We carried out a pot experiment in which three insect-pollinated plant species were grown in binary mixtures with four wind-pollinated plant species, differing in their competitive ability. Along the flowering period, we measured floral traits of the insect-pollinated species involved in attractiveness to pollinators (i.e. floral display size, flower size, daily and total 1) flower production, 2) nectar volume, 3) amount of sucrose allocated to nectar). Final plant biomass was measured to quantify competitive interactions. For two out of three insect-pollinated species, we found that the presence of a wind-pollinated species can negatively impact floral traits involved in attractiveness to pollinators. This effect was stronger with wind-pollinated species that induced stronger competitive interactions. These results stress the importance of studying the whole plant community (and not just the insect-pollinated plant community) when working on plant-pollinator interactions.

‣ Large scale artificial rearing of Anastrepha sp.1 aff. fraterculus (Diptera: Tephritidae) in Brazi.

WALDER, J. M. M.; MORELLI, R.; COSTA, K. Z.; FAGGIONI, K. M.; SANCHES, P. A.; PARANHOS, B. A. J.; BENTO, J. M. S.; COSTA, M. de L. Z.
Fonte: Scientia Aggricola, Piracicaba, v.71, n.4, p.281-286, jul./aug. 2014. Publicador: Scientia Aggricola, Piracicaba, v.71, n.4, p.281-286, jul./aug. 2014.
Tipo: Artigo em periódico indexado (ALICE)
Português
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Some species of the genus Anastrepha (Diptera: Tephritidae) are successfully man - aged by matching the sterile insect technique with parasitoid releases. Such strategies used in integrated pest management can be implemented only where insect mass-rearing programs are feasible. In this study, we show the process of domestication, rearing technology and qual - ity control data obtained from 54 generations of Anastrepha sp.1 aff. fraterculus (Wiedemann,1830) kept under fully artificial conditions. Eggs were collected by an artificial oviposition panel consisting of one side of the cage made of blue voile fabric externally covered with a thin layer of silicon rubber. They were then air-bubbled in water at 25 ºC for 48 h before seeding. Larvae were reared on the regular laboratory artificial diet with 66 % of agar reduction turning over a semi-liquid diet, which reduced costs and improved insect quality. The adult and larval diets were composed of local ingredients including hydrolyzed yeast. When large-scale production of this fly is contemplated, the critical stage is larval development. This system of artificial rearing for A. fraterculus sp.1 developed in Brazil, allows for the production of a large number of insects of excellent quality using local ingredients and less agar in diet composition than the original medium used for this species. By reducing the interval of egg collection...

‣ The analysis of gene transcripts associated with conidiation in the insect pathogenic fungus, Metarhizium anisopliae /

Small, Cherrie-Lee.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
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Conidia of the insect pathogenic fungus, Metarhizium anisopliae play an important role in pathogenicity because they are the infective propagules that adhere to the surface of the insect, then germinate and give rise to hyphal penetration of the insect cuticle. Conidia are produced in the final stages of insect infection as the mycelia emerge from the insect cadaver. The genes associated with conidiation have not yet been studied in this fiingus. hi this study we used the PCR-based technique, suppression subtractive hybridization (SSH) to selectively amplify conidial-associated genes in M. anisopliae. We then identified the presence of these differentially expressed genes using the National Center for Biotechnology Information database. One of the transcripts encoded an extracellular subtilisin-like protease, Prl, which plays a fundamental role in cuticular protein degradation. Analysis of the patterns of gene expression of the transcripts using RT-PCR indicated that conidial-associated cDNAs are expressed during the development of the mature conidium. RT-PCR analysis was also performed to examine in vivo expression of Prl during infection of waxworm larvae {Galleria mellonelld). Results showed expression of Prl as mycelia emerge and produce conidia on the surface of the cadaver. It is well documented that Prl is produced during the initial stages of transcuticular penetration by M. anisopliae. We suggest that upregulation of Prl is part of the mechanism by which reverse (from inside to the outside of the host) transcuticular penetration of the insect cuticle allows subsequent conidiation on the cadaver.

‣ Biomechanical Properties of Insect Wings: The Stress Stiffening Effects on the Asymmetric Bending of the Allomyrina dichotoma Beetle's Hind Wing

Ha, Ngoc San; Truong, Quang Tri; Goo, Nam Seo; Park, Hoon Cheol
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 05/12/2013 Português
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Although the asymmetry in the upward and downward bending of insect wings is well known, the structural origin of this asymmetry is not yet clearly understood. Some researchers have suggested that based on experimental results, the bending asymmetry of insect wings appears to be a consequence of the camber inherent in the wings. Although an experimental approach can reveal this phenomenon, another method is required to reveal the underlying theory behind the experimental results. The finite element method (FEM) is a powerful tool for evaluating experimental measurements and is useful for studying the bending asymmetry of insect wings. Therefore, in this study, the asymmetric bending of the Allomyrina dichotoma beetle's hind wing was investigated through FEM analyses rather than through an experimental approach. The results demonstrated that both the stressed stiffening of the membrane and the camber of the wing affect the bending asymmetry of insect wings. In particular, the chordwise camber increased the rigidity of the wing when a load was applied to the ventral side, while the spanwise camber increased the rigidity of the wing when a load was applied to the dorsal side. These results provide an appropriate explanation of the mechanical behavior of cambered insect wings...

‣ The promoter of the late p10 gene in the insect nuclear polyhedrosis virus Autographa californica: activation by viral gene products and sensitivity to DNA methylation.

Knebel, D; Lübbert, H; Doerfler, W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1985 Português
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In lepidopteran insect cells infected with the baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV), two major late viral gene products are expressed: the polyhedrin, a 28 000 mol. wt. protein which makes up the mass of the nuclear inclusion bodies, and a 10 000 mol. wt. protein (p10) whose function is unknown. The nucleotide sequences of these strong promoters conform to those of other eukaryotic promoters and are rich in AT base pairs. We used the pSVO-CAT construct containing the prokaryotic gene chloramphenicol acetyl transferase (CAT) to study the function of the p10 gene promoter in insect and mammalian cells. Upon transfection of the pAcp10-CAT construct, which contained 402 bp of the p10 gene of AcNPV DNA in the HindIII site of pSVO-CAT, CAT activity was determined. The p10 gene promoter was inactive in human HeLa cells and in uninfected Spodoptera frugiperda insect cells. The same promoter was active, however, in AcNPV-infected S. frugiperda cells and exhibited optimal activity when cells were transfected 18 h after infection with the insect virus. This finding demonstrated directly that the p10 gene promoter required other viral gene products for its activity in insect cells. The nature of these products was unknown. The p10 gene promoter sequence contained one 5'-CCGG-3' site 40 bp upstream from the cap site of the gene and two such sites 178 and 192 bp downstream from the ATG initiation codon of the gene. Since Drosophila DNA or S. frugiperda DNA contained no 5-methylcytosine or extremely small amounts of it...

‣ Development of insect resistant maize plants expressing a chitinase gene from the cotton leaf worm, Spodoptera littoralis

Osman, Gamal H.; Assem, Shireen K.; Alreedy, Rasha M.; El-Ghareeb, Doaa K.; Basry, Mahmoud A.; Rastogi, Anshu; Kalaji, Hazem M.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Text
Publicado em 14/12/2015 Português
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Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents. Targeting chitin associated with the extracellular matrices or cell wall by insect chitinases may be an effective approach for controlling pest insects and pathogenic fungi. The ability of chitinases to attack and digest chitin in the peritrophic matrix or exoskeleton raises the possibility to use them as insect control method. In this study, an insect chitinase cDNA from cotton leaf worm (Spodoptera littoralis) has been synthesized. Transgenic maize plant system was used to improve its tolerance against insects. Insect chitinase transcripts and proteins were expressed in transgenic maize plants. The functional integrity and expression of chitinase in progenies of the transgenic plants were confirmed by insect bioassays. The bioassays using transgenic corn plants against corn borer (Sesamia cretica) revealed that ~50% of the insects reared on transgenic corn plants died, suggesting that transgenic maize plants have enhanced resistance against S. cretica.

‣ Insect herbivores associated with Baccharis dracunculifolia (Asteraceae): responses of gall-forming and free-feeding insects to latitudinal variation

Fagundes,Marcílio; Wilson Fernandes,G
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 Português
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The spatial heterogeneity hypothesis has been invoked to explain the increase in species diversity from the poles to the tropics: the tropics may be more diverse because they contain more habitats and microhabitats. In this paper, the spatial heterogeneity hypothesis prediction was tested by evaluating the variation in richness of two guilds of insect herbivores (gall-formers and free-feeders) associated with Baccharis dracunculifolia (Asteraceae) along a latitudinal variation in Brazil. The seventeen populations of B. dracunculifolia selected for insect herbivores sampling were within structurally similar habitats, along the N-S distributional limit of the host plant, near the Brazilian sea coast. Thirty shrubs were surveyed in each host plant population. A total of 8 201 galls and 864 free-feeding insect herbivores belonging to 28 families and 88 species were sampled. The majority of the insects found on B. dracunculifolia were restricted to a specific site rather than having ageographic distribution mirroring that of the host plant. Species richness of free-feeding insects was not affected by latitudinal variation corroborating the spatial heterogeneity hypothesis. Species richness of gall-forming insects was positively correlated with latitude...