Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 562
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 571(7765): E7, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31263274

RESUMO

Change history: In this Article, the original affiliation 2 was not applicable and has been removed. In addition, in the Acknowledgements there was a statement missing and an error in a name. These errors have been corrected online.

2.
Nature ; 568(7753): 487-492, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31019327

RESUMO

Carbon and other volatiles in the form of gases, fluids or mineral phases are transported from Earth's surface into the mantle at convergent margins, where the oceanic crust subducts beneath the continental crust. The efficiency of this transfer has profound implications for the nature and scale of geochemical heterogeneities in Earth's deep mantle and shallow crustal reservoirs, as well as Earth's oxidation state. However, the proportions of volatiles released from the forearc and backarc are not well constrained compared to fluxes from the volcanic arc front. Here we use helium and carbon isotope data from deeply sourced springs along two cross-arc transects to show that about 91 per cent of carbon released from the slab and mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition. Around an additional three per cent is incorporated into the biomass through microbial chemolithoautotrophy, whereby microbes assimilate inorganic carbon into biomass. We estimate that between 1.2 × 108 and 1.3 × 1010 moles of carbon dioxide per year are released from the slab beneath the forearc, and thus up to about 19 per cent less carbon is being transferred into Earth's deep mantle than previously estimated.


Assuntos
Dióxido de Carbono/análise , Sequestro de Carbono , Sedimentos Geológicos/química , Biomassa , Isótopos de Carbono , Costa Rica , Sedimentos Geológicos/microbiologia , Hélio
4.
Trop Anim Health Prod ; 55(3): 190, 2023 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-37140716

RESUMO

The objective of the present study was to evaluate the effects of increasing doses of protease on broilers from 1 to 42 days of age. A total of 1290 Ross AP broilers were used, distributed among five treatments: positive control diet, negative control diet (NC), NC + 50 ppm of protease, NC + 100 ppm of protease, and NC + 200 ppm of protease. Each treatment contained six replicates of 43 animals each. The inclusion of proteases in the diet had effects (P < 0.05) on body weight, feed intake, weight gain, and feed conversion in the 12 to 21 day period; body weight, weight gain, and feed intake in the 29 to 42 day period; nutrient digestibility (energy metabolizability coefficient and crude protein at 28 days); and intestinal parameters (crypt and muscle width of jejunum and ileum at 28 days and villus length, crypt length, and jejunum thickness muscle layer at 42 days). These results indicate that the inclusion of protease in broiler feed can improve production parameters when the amount of crude protein in the diet is reduced.


Assuntos
Dieta com Restrição de Proteínas , Peptídeo Hidrolases , Animais , Peptídeo Hidrolases/metabolismo , Dieta com Restrição de Proteínas/veterinária , Galinhas/fisiologia , Dieta/veterinária , Nutrientes/fisiologia , Carne , Peso Corporal , Aumento de Peso , Ração Animal/análise , Suplementos Nutricionais , Fenômenos Fisiológicos da Nutrição Animal
5.
J Math Biol ; 83(4): 42, 2021 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-34564787

RESUMO

Nonpharmaceutical interventions (NPI) such as banning public events or instituting lockdowns have been widely applied around the world to control the current COVID-19 pandemic. Typically, this type of intervention is imposed when an epidemiological indicator in a given population exceeds a certain threshold. Then, the nonpharmaceutical intervention is lifted when the levels of the indicator used have decreased sufficiently. What is the best indicator to use? In this paper, we propose a mathematical framework to try to answer this question. More specifically, the proposed framework permits to assess and compare different event-triggered controls based on epidemiological indicators. Our methodology consists of considering some outcomes that are consequences of the nonpharmaceutical interventions that a decision maker aims to make as low as possible. The peak demand for intensive care units (ICU) and the total number of days in lockdown are examples of such outcomes. If an epidemiological indicator is used to trigger the interventions, there is naturally a trade-off between the outcomes that can be seen as a curve parameterized by the trigger threshold to be used. The computation of these curves for a group of indicators then allows the selection of the best indicator the curve of which dominates the curves of the other indicators. This methodology is illustrated with indicators in the context of COVID-19 using deterministic compartmental models in discrete-time, although the framework can be adapted for a larger class of models.


Assuntos
COVID-19 , Pandemias , Controle de Doenças Transmissíveis , Humanos , Políticas , SARS-CoV-2
6.
Bioprocess Biosyst Eng ; 44(7): 1525-1538, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33860372

RESUMO

A biofertilizer of Azospirillum brasilense was produced in solid-state culture (SSC) from laboratory to pilot scale. Similar operation conditions (continuous aeration and mild intermittent mixing) and two dimensionless numbers with similar L/D ratio and a similar working volume were applied to reach a scale-up factor of 75. An innovative bioreactor with rotating helical ribbons (15 kg wet matter) was used at pilot scale. A mathematical model was proposed and validated to evaluate the respirometry trends at laboratory and pilot scale exhibiting similar behavior. The cell viability was (1.3 ± 0.4) × 109 and (1.3 ± 0.3) × 109 colony-forming units per gram of initial dry mass at laboratory and pilot scale, at 36 and 43 h, respectively. A. brasilense maintains its viability twelve months of storage at 4 and 30 °C. This is the first report of A. brasilense being cultivated in SSC under controlled conditions. SSC processes involving unicellular microorganisms with tolerance to agitation are a promising technology to produce biofertilizers.


Assuntos
Azospirillum brasilense/metabolismo , Reatores Biológicos , Biotecnologia/métodos , Glicerol/química , Microbiologia Industrial/métodos , Fermentação , Fertilizantes , Concentração de Íons de Hidrogênio , Cinética , Laboratórios , Microscopia Eletrônica de Varredura , Modelos Teóricos , Consumo de Oxigênio , Células-Tronco
7.
Rheumatol Int ; 40(11): 1857-1864, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32200425

RESUMO

There is a high percentage of error in the approach of patients with joint pain by primary care physicians. An algorithm can help improve this misdiagnosis problem. Our study seeks to determine the effectiveness of an algorithm when used by primary care physicians for the diagnosis of cases of joint pain patients. A randomized clinical experiment was carried out. Primary care physicians from five cities in Colombia developed a series of clinical cases, which were presented to them through a website on their personal cell phones. Half of the doctors developed the cases using the diagnostic algorithm, and the other half developed the cases without the use of the algorithm. Main measures were proportion of correct diagnosis, number, type of laboratory and diagnostic images requested for the diagnostic approach of clinical cases. Two hundred and twenty-four primary care physicians participated. The overall proportion of cases correctly diagnosed was 37.3% higher in the intervention group; we found a greater difference in cases of spondyloarthritis (60.8%), followed by systemic lupus erythematosus with joint involvement (32.2%), rheumatoid arthritis (30.3%) and osteoarthritis (25.9%). The average number of tests requested to develop clinical cases was lower in the intervention group than in the control group, both globally and for each of the four diseases, with statistically significant differences for each of the comparisons. The diagnostic algorithm proved to be an effective tool when used by primary care physicians; the proportion of correct diagnoses increased, and the number of tests requested in the development of the cases decreased.


Assuntos
Algoritmos , Artralgia/diagnóstico , Artrite Reumatoide/diagnóstico , Erros de Diagnóstico/prevenção & controle , Lúpus Eritematoso Sistêmico/diagnóstico , Osteoartrite/diagnóstico , Médicos de Atenção Primária , Espondiloartropatias/diagnóstico , Adulto , Artralgia/etiologia , Artrite Reumatoide/complicações , Colômbia , Feminino , Humanos , Lúpus Eritematoso Sistêmico/complicações , Masculino , Pessoa de Meia-Idade , Osteoartrite/complicações , Distribuição Aleatória , Espondiloartropatias/complicações
8.
Phys Rev Lett ; 123(9): 092001, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31524471

RESUMO

We study the nature of the new signal reported by LHCb in the J/ψp spectrum. Based on the S-matrix principles, we perform a minimum-bias analysis of the underlying reaction amplitude, focusing on the analytic properties that can be related to the microscopic origin of the P_{c}(4312)^{+} peak. By exploring several amplitude parametrizations, we find evidence for the attractive effect of the Σ_{c}^{+}D[over ¯]^{0} channel, which is not strong enough, however, to form a bound state.

9.
Phys Rev Lett ; 122(4): 042002, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30768338

RESUMO

Mapping states with explicit gluonic degrees of freedom in the light sector is a challenge, and has led to controversies in the past. In particular, the experiments have reported two different hybrid candidates with spin-exotic signature, π_{1}(1400) and π_{1}(1600), which couple separately to ηπ and η^{'}π. This picture is not compatible with recent Lattice QCD estimates for hybrid states, nor with most phenomenological models. We consider the recent partial wave analysis of the η^{(')}π system by the COMPASS Collaboration. We fit the extracted intensities and phases with a coupled-channel amplitude that enforces the unitarity and analyticity of the S matrix. We provide a robust extraction of a single exotic π_{1} resonant pole, with mass and width 1564±24±86 and 492±54±102 MeV, which couples to both η^{(')}π channels. We find no evidence for a second exotic state. We also provide the resonance parameters of the a_{2}(1320) and a_{2}^{'}(1700).

10.
J Neural Transm (Vienna) ; 126(5): 637-644, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30874897

RESUMO

Family, twin, and adoption studies have suggested that genetic factors might be involved in suicidal behavior. Corticotropin-releasing receptor type 1 (CRHR1) and 2 (CRHR2) genes play a key role in the activation and modulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is considered a major stress regulator. Childhood trauma is an environmental risk factor associated with suicide attempt (SA) and it has been related to HPA axis dysregulation. This study aimed at analyzing the relationship of CRHR1 and CRHR2 genes with childhood trauma concerning the development of SA. In this study, we included 366 affective disorder patients. Among them, 183 patients had SA at least once and 183 had not SA. Information regarding SA and childhood trauma was obtained from medical records. Multifactor Dimensionality Reduction program was used to detect gene-environment interactions between CRHR1 (rs110402, rs242924, and rs16940665) and CRHR2 (rs2190242, rs2284217, and rs2014663) with childhood trauma in SA. The analysis showed an interaction of CRHR1 and CRHR2 with childhood trauma, thus conferring increased risk of having presented at least one SA (OR 7.44; 95% CI 4.58-12.07; p < 0.0001). In addition, we observed the following in the trauma subtypes analysis: physical negligence (OR 4.72; 95% CI 3.01-7.40; p < 0.0001), emotional abuse (OR 5.76; 95% CI 3.67-9.05; p < 0.0001), and sexual abuse (OR 5.70; 95% CI 3.62-8.97; p < 0.0001). Our results suggested that genetic variants of CRHR1 and CRHR2 genes in addition to physical negligence, and emotional and sexual abuse, contribute to increase risk of presented at least one SA.


Assuntos
Trauma Psicológico/psicologia , Receptores de Hormônio Liberador da Corticotropina/genética , Tentativa de Suicídio , Adolescente , Adulto , Criança , Feminino , Predisposição Genética para Doença/genética , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Adulto Jovem
11.
FEMS Yeast Res ; 18(8)2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29982373

RESUMO

Yarrowia lipolytica is an ascomycetous dimorphic yeast with immense potential for industrial applications, including bioremediation of crude oil-contaminated environments. It has been shown that a dimorphic marine isolate of Y. lipolytica (var. indica) has significant capacity to degrade fatty acids and alkanes, when in its yeast morphology. It has also been demonstrated that polyamines play an important role in the yeast-to-mycelium transition of different strains of Y. lipolytica that are unable to utilize those carbon sources. To determine the role of polyamines on their capacity to utilize oils and hydrocarbons, on the dimorphic transition, and also on other characteristics of the var. indica strain of Y. lipolytica, we proceeded to obtain ornithine decarboxylase minus (odc-) mutants. These mutants behaved as yeasts independently of the concentrations of putrescine added. Further, they conserved the oil-degrading capacity of the parent strain. The odc- mutant can thus be used in fatty acid degradation, and oil spill remediation with distinct advantages.


Assuntos
Poluentes Ambientais/metabolismo , Óleos/metabolismo , Poliaminas/metabolismo , Yarrowia/efeitos dos fármacos , Yarrowia/metabolismo , Biotransformação , Mutação , Micélio/citologia , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Ornitina Descarboxilase/deficiência , Yarrowia/citologia , Yarrowia/crescimento & desenvolvimento
12.
Br J Anaesth ; 120(5): 969-977, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29661414

RESUMO

BACKGROUND: Obesity has been associated with reduced dexmedetomidine clearance, suggesting impaired hepatic function or reduced hepatic blood flow. The aim of this study was to clarify the effect of obesity in dexmedetomidine metabolic clearance. METHODS: Forty patients, ASA I-III, 18-60 yr old, weighing 47-126 kg, scheduled for abdominal laparoscopic surgery, were enrolled. Anaesthetic agents (propofol, remifentanil, and dexmedetomidine) were dosed based on lean body weight measured by dual X-ray absorptiometry. Serial venous samples were drawn during and after dexmedetomidine infusion. A pharmacokinetic analysis was undertaken using non-linear mixed-effect models. In the modelling approach, the total body weight, lean body weight, and adjusted body weight were first tested as size descriptors for volumes and clearances. Hepatic blood flow, liver histopathology, liver enzymes, and gene expression of metabolic enzymes (UGT2B10 and UGT1A4) were tested as covariates of dexmedetomidine metabolic clearance. A decrease in NONMEM objective function value (ΔOFV) of 3.84 points, for an added parameter, was considered significant at the 0.05 level. RESULTS: A total of 637 dexmedetomidine serum samples were obtained. A two-compartmental model scaled to measured lean weight adequately described the dexmedetomidine pharmacokinetics. Liver blood flow was a covariate for dexmedetomidine clearance (ΔOFV=-5.878). Other factors, including fat mass, histopathological damage, and differential expression of enzymes, did not affect the dexmedetomidine clearance in the population studied (ΔOFV<3.84). CONCLUSIONS: We did not find a negative influence of obesity in dexmedetomidine clearance when doses were adjusted to lean body weight. Liver blood flow showed a significant effect on dexmedetomidine clearance. CLINICAL TRIAL REGISTRATION: NCT02557867.


Assuntos
Tecido Adiposo/metabolismo , Dexmedetomidina/farmacocinética , Hipnóticos e Sedativos/farmacocinética , Obesidade/metabolismo , Adulto , Chile , Feminino , Humanos , Masculino , Taxa de Depuração Metabólica , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
13.
J Helminthol ; 94: e8, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30428941

RESUMO

Hookworms of the genus Uncinaria parasitize pinniped pups in various locations worldwide. Four species have been described, two of which parasitize pinniped pups in the southern hemisphere: Uncinaria hamiltoni parasitizes Otaria flavescens and Arctocephalus australis from the South American coast, and Uncinaria sanguinis parasitizes Neophoca cinerea from the Australian coast. However, their geographical ranges and host specificity are unknown. Uncinaria spp. are morphologically similar, but molecular analyses have allowed the recognition of new species in the genus Uncinaria. We used nuclear genetic markers (internal transcribed spacer (ITS) and large subunit (LSU) rDNA) and a mitochondrial genetic marker (cytochrome c oxidase subunit I (COI)) to evaluate the phylogenetic relationships of Uncinaria spp. parasitizing A. australis and O. flavescens from South American coasts (Atlantic and Pacific coasts). We compared our sequences with published Uncinaria sequences. A Generalized Mixed Yule Coalescent (GMYC) analysis was also used to delimit species, and principal component analysis was used to compare morphometry among Uncinaria specimens. Parasites were sampled from A. australis from Peru (12°S), southern Chile (42°S), and the Uruguayan coast, and from O. flavescens from northern Chile (24°S) and the Uruguayan coast. Morphometric differences were observed between Uncinaria specimens from both South American coasts and between Uncinaria specimens from A. australis in Peru and southern Chile. Phylogenetic and GMYC analyses suggest that south-eastern Pacific otariid species harbour U. hamiltoni and an undescribed putative species of Uncinaria. However, more samples from A. australis and O. flavescens are necessary to understand the phylogenetic patterns of Uncinaria spp. across the South Pacific.


Assuntos
Ancylostomatoidea/crescimento & desenvolvimento , Ancylostomatoidea/isolamento & purificação , Caniformia/parasitologia , Infecções por Uncinaria/veterinária , Ancylostomatoidea/classificação , Ancylostomatoidea/genética , Animais , Chile , DNA de Helmintos/genética , DNA Espaçador Ribossômico/genética , Otárias/parasitologia , Infecções por Uncinaria/parasitologia , Peru , Filogenia
15.
Fungal Genet Biol ; 101: 34-45, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28285895

RESUMO

Previously, we demonstrated that when Ustilago maydis (DC) Cda., a phytopathogenic basidiomycete and the causal agent of corn smut, is grown in the vicinity of maize embryogenic calli in a medium supplemented with the herbicide Dicamba, it developed gastroid-like basidiocarps. To elucidate the molecular mechanisms involved in the basidiocarp development by the fungus, we proceeded to analyze the transcriptome of the process, identifying a total of 2002 and 1064 differentially expressed genes at two developmental stages, young and mature basidiocarps, respectively. Function of these genes was analyzed with the use of different databases. MIPS analysis revealed that in the stage of young basidiocarp, among the ca. two thousand differentially expressed genes, there were some previously described for basidiocarp development in other fungal species. Additional elements that operated at this stage included, among others, genes encoding the transcription factors FOXO3, MIG3, PRO1, TEC1, copper and MFS transporters, and cytochromes P450. During mature basidiocarp development, important up-regulated genes included those encoding hydrophobins, laccases, and ferric reductase (FRE/NOX). The demonstration that a mapkk mutant was unable to form basidiocarps, indicated the importance of the MAPK signaling pathway in this developmental process.


Assuntos
Dicamba/farmacologia , Carpóforos/genética , Transcriptoma/efeitos dos fármacos , Ustilago/genética , Carpóforos/efeitos dos fármacos , Carpóforos/crescimento & desenvolvimento , Proteínas Fúngicas/biossíntese , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Doenças das Plantas/microbiologia , Ustilago/efeitos dos fármacos , Ustilago/crescimento & desenvolvimento , Ustilago/patogenicidade , Zea mays/microbiologia
16.
Clin Exp Allergy ; 47(11): 1398-1408, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28618148

RESUMO

BACKGROUND: Recently, the nature of the lipid-ligand of Pru p 3, one of the most common plant food allergens in southern Europe, has been identified as a derivative of the alkaloid camptothecin bound to phytosphingosine. However, the origin of its immunological activity is still unknown. OBJECTIVE: We sought to evaluate the role of the Pru p 3 lipid-ligand in the immunogenic activity of Pru p 3. METHODS: In vitro cultures of different cell types (monocyte-derived dendritic cells [moDCs], PBMCs [peripheral blood mononuclear cells] and epithelial and iNKT-hybridoma cell lines) have been used to determine the immunological capacity of the ligand, by measuring cell proliferation, maturation markers and cytokine production. To study the capacity of the lipid-ligand to promote sensitization to Pru p 3 in vivo, a mouse model of anaphylaxis to peach has been produced and changes in the humoral and basophil responses have been analysed. RESULTS: The lipid-ligand of Pru p 3 induced maturation of moDCsc and proliferation of PBMCs. Its immunological activity resided in the phytosphingosine tail of the ligand. The adjuvant activity of the ligand was also confirmed in vivo, where the complex of Pru p 3-ligand induced higher levels of IgE than Pru p 3 alone. The immunological capacity of the Pru p 3 ligand was mediated by CD1d, as maturation of moDCs was inhibited by anti-CD1d antibodies and Pru p 3-ligand co-localized with CD1d on epithelial cells. Finally, Pru p 3-ligand presented by CD1d was able to interact with iNKTs. CONCLUSIONS AND CLINICAL RELEVANCE: The Pru p 3 lipid-ligand could act as an adjuvant to promote sensitization to Pru p 3, through its recognition by CD1d receptors. This intrinsic adjuvant activity of the accompanying lipid cargo could be a general essential feature of the mechanism underlying the phenomenon of allergenicity.


Assuntos
Antígenos de Plantas/imunologia , Hipersensibilidade Alimentar/imunologia , Proteínas de Plantas/imunologia , Sequência de Aminoácidos , Animais , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Antígenos CD1d/imunologia , Antígenos CD1d/metabolismo , Antígenos de Plantas/administração & dosagem , Antígenos de Plantas/química , Citocinas/metabolismo , Europa (Continente) , Imunização , Imunoglobulina E/imunologia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Ligantes , Lipídeos/imunologia , Ativação Linfocitária/imunologia , Camundongos , Modelos Moleculares , Células T Matadoras Naturais/imunologia , Células T Matadoras Naturais/metabolismo , Proteínas de Plantas/administração & dosagem , Proteínas de Plantas/química , Ligação Proteica , Conformação Proteica , Linfócitos T/imunologia , Linfócitos T/metabolismo
17.
Mol Ecol ; 26(3): 887-903, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28026895

RESUMO

Population genetic studies are efficient for inferring the invasion history based on a comparison of native and invasive populations, especially when conducted at species scale. An expected outcome in invasive populations is variability loss, and this is especially true in self-fertilizing species. We here focus on the self-fertilizing Pseudosuccinea columella, an invasive hermaphroditic freshwater snail that has greatly expanded its geographic distribution and that acts as intermediate host of Fasciola hepatica, the causative agent of human and veterinary fasciolosis. We evaluated the distribution of genetic diversity at the largest geographic scale analysed to date in this species by surveying 80 populations collected during 16 years from 14 countries, using eight nuclear microsatellites and two mitochondrial genes. As expected, populations from North America, the putative origin area, were strongly structured by selfing and history and harboured much more genetic variability than invasive populations. We found high selfing rates (when it was possible to infer it), none-to-low genetic variability and strong population structure in most invasive populations. Strikingly, we found a unique genotype/haplotype in populations from eight invaded regions sampled all over the world. Moreover, snail populations resistant to infection by the parasite are genetically distinct from susceptible populations. Our results are compatible with repeated introductions in South America and flash worldwide invasion by this unique genotype/haplotype. Our study illustrates the population genetic consequences of biological invasion in a highly selfing species at very large geographic scale. We discuss how such a large-scale flash invasion may affect the spread of fasciolosis.


Assuntos
Genética Populacional , Autofertilização , Caramujos/genética , Animais , Genes Mitocondriais , Genótipo , Haplótipos , Espécies Introduzidas , Repetições de Microssatélites , América do Norte , América do Sul
19.
Bull Entomol Res ; 106(6): 801-808, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27573283

RESUMO

Asexual reproduction is very common in invasive insect pest. In the recent years, increasing evidences have shown that some invasive asexual lineages display an outstanding capacity to predominate in space and persist on time (superclones). However, little is known about the host-use behavior of these superclones. The English grain aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae) is one of the major pests of cereals worldwide. Chilean populations of the grain aphid are characterized by a high degree of heterozygosity and low genotypic variability across regions and years, with only four predominant superclone genotypes representing nearly 90% of populations. In this study, (1) the reproductive performance and (2) the probing behavior followed a host shift of one superclone and one non-superclone of S. avenae, were compared. The host plant in the superclone did not affect the reproductive performance, while in the non-superclone was lower on highly defended wheat seedling. The experimental switching of the host plants from barley (without chemical defenses) to two wheat species with low and high levels of chemical defenses, revealed that superclone exhibited a flexible probing activities related to access of sieve elements, while the non-superclone exhibited rigid responses. These findings are consistent with the pattern of occurrence of these genotypes in the field on cereals with different plant defenses (e.g. benzoxazinoids). These responses are discussed on the view of developing new strategies for the management in invasive populations of aphid pest species.


Assuntos
Adaptação Fisiológica , Afídeos/genética , Reprodução Assexuada , Animais , Afídeos/fisiologia , Grão Comestível , Comportamento Alimentar , Variação Genética , Genótipo , Heterozigoto , Espécies Introduzidas , Especificidade da Espécie
20.
Insect Mol Biol ; 24(6): 649-61, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26537737

RESUMO

Bark beetles of the genus Dendroctonus are important components of coniferous forests. During host colonization, they must overcome the chemical defences of their host trees, which are metabolized by cytochrome P450 (CYP or P450) enzymes to compounds that are readily excreted. In this study, we report the relative expression (quantitative real-time PCR) of four orthologous cytochrome P450 genes (CYP6BW5, CYP6DG1, CYP6DJ2 and CYP9Z20) in Dendroctonus rhizophagus and Dendroctonus valens forced to attack host trees at 8 and 24 h following forced attack and in four stages during natural colonization [solitary females boring the bark (T1); both male and female members of couples before oviposition (T2); both male and female members of couples during oviposition (T3), and solitary females inside the gallery containing eggs (T4)]. For both species gene expression was different compared with that observed in insects exposed to single monoterpenes in the laboratory, and the expression patterns were significantly different amongst species, sex, gut region and exposure time or natural colonization stage. The induction of genes (CYP6BW5v1, CYP6DJ2v1 and CYP9Z20v1 from D. rhizophagus, as well as CYP6DG1v3 from D. valens) correlated with colonization stage as well as with the increase in oxygenated monoterpenes in the gut of both species throughout the colonization of the host. Our results point to different functions of these orthologous genes in both species.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Pinus/parasitologia , Gorgulhos/enzimologia , Animais , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/genética , Feminino , Trato Gastrointestinal/enzimologia , Regulação da Expressão Gênica , Masculino , México , Monoterpenos/metabolismo , Oviposição , Pinus/metabolismo , Fatores de Tempo , Gorgulhos/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA