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1.
Cell ; 187(8): 1971-1989.e16, 2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38521060

RESUMO

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) share many clinical, pathological, and genetic features, but a detailed understanding of their associated transcriptional alterations across vulnerable cortical cell types is lacking. Here, we report a high-resolution, comparative single-cell molecular atlas of the human primary motor and dorsolateral prefrontal cortices and their transcriptional alterations in sporadic and familial ALS and FTLD. By integrating transcriptional and genetic information, we identify known and previously unidentified vulnerable populations in cortical layer 5 and show that ALS- and FTLD-implicated motor and spindle neurons possess a virtually indistinguishable molecular identity. We implicate potential disease mechanisms affecting these cell types as well as non-neuronal drivers of pathogenesis. Finally, we show that neuron loss in cortical layer 5 tracks more closely with transcriptional identity rather than cellular morphology and extends beyond previously reported vulnerable cell types.


Assuntos
Esclerose Lateral Amiotrófica , Degeneração Lobar Frontotemporal , Córtex Pré-Frontal , Animais , Humanos , Camundongos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Demência Frontotemporal/genética , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/metabolismo , Degeneração Lobar Frontotemporal/patologia , Perfilação da Expressão Gênica , Neurônios/metabolismo , Córtex Pré-Frontal/metabolismo , Córtex Pré-Frontal/patologia , Análise da Expressão Gênica de Célula Única
2.
Proc Natl Acad Sci U S A ; 119(35): e2205425119, 2022 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-35994651

RESUMO

Chorea-acanthocytosis (ChAc) and McLeod syndrome are diseases with shared clinical manifestations caused by mutations in VPS13A and XK, respectively. Key features of these conditions are the degeneration of caudate neurons and the presence of abnormally shaped erythrocytes. XK belongs to a family of plasma membrane (PM) lipid scramblases whose action results in exposure of PtdSer at the cell surface. VPS13A is an endoplasmic reticulum (ER)-anchored lipid transfer protein with a putative role in the transport of lipids at contacts of the ER with other membranes. Recently VPS13A and XK were reported to interact by still unknown mechanisms. So far, however, there is no evidence for a colocalization of the two proteins at contacts of the ER with the PM, where XK resides, as VPS13A was shown to be localized at contacts between the ER and either mitochondria or lipid droplets. Here we show that VPS13A can also localize at ER-PM contacts via the binding of its PH domain to a cytosolic loop of XK, that such interaction is regulated by an intramolecular interaction within XK, and that both VPS13A and XK are highly expressed in the caudate neurons. Binding of the PH domain of VPS13A to XK is competitive with its binding to intracellular membranes that mediate other tethering functions of VPS13A. Our findings support a model according to which VPS13A-dependent lipid transfer between the ER and the PM is coupled to lipid scrambling within the PM. They raise the possibility that defective cell surface exposure of PtdSer may be responsible for neurodegeneration.


Assuntos
Proteínas de Transporte , Membrana Celular , Lipídeos , Proteínas de Transporte Vesicular , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Membrana Celular/metabolismo , Retículo Endoplasmático/enzimologia , Retículo Endoplasmático/metabolismo , Humanos , Neuroacantocitose/metabolismo , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismo
3.
Bull Entomol Res ; 110(2): 270-277, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31495348

RESUMO

Predation by Engytatus varians (Distant) adults on different development stages of the prey species Bactericera cockerelli (Sulcer) (egg, second, and third nymphal instars), Spodoptera exigua (Hübner) and Spodoptera frugiperda (J. E. Smith) (egg, first, and second larval instars) was evaluated using tomato (Solanum lycopersicum L.) leaflets or plants. These insects are the primary pest of several agriculturally important crops. The influence of E. varians age on the predation capacity was also analysed. Engytatus varians females consumed significantly more B. cockerelli eggs and nymphs than males. Additionally, female predators consumed significantly more second than third instar prey at two predator ages, while males consumed significantly more the second instar than third instar prey at all predator ages. In most of the cases, females also consumed significantly more S. exigua and S. frugiperda eggs than males; however, in terms of larvae consumption, this difference was observed only in some predator ages. Females consumed more the first than second instar S. exigua than males, whereas this behaviour was only observed in males when the predators were 15 and 17 days old. No significant differences were observed in the consumption of first and second instar of S. frugiperda for both sexes of the predators. Predator age did not cause any systematic effects on the predation rates of any prey species. Based on these results, we confirmed that E. varians has potential as a biological control agent for B. cockerelli and also for the Spodoptera species bioassayed.


Assuntos
Hemípteros , Comportamento Predatório , Spodoptera , Animais , Feminino , Larva , Masculino , Ninfa , Óvulo
4.
Europace ; 20(6): 993-1000, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28472387

RESUMO

Aims: To determine the impact of permanent cardiac pacing after transcatheter aortic valve implantation (TAVI) with the CoreValveTM prosthesis in terms of all-cause mortality and morbidity [rehospitalizations for heart failure (HF) or stroke] at the long-term follow-up. Methods and results: The prospective analysis comprised 259 patients (138 women, 53.3%, age 78 ± 6 years) treated by a CoreValveTM prosthesis from April 2008 to December 2015. Forty-two patients were excluded for analysis: 9 with pre-existing permanent pacemaker (PPM) implantation, 19 who required a PPM during the follow-up and 14 patients because of hospital mortality during or after the CoreValveTM prosthesis implantation procedure. The remaining 217 patients were divided in two groups: Group-1 included those patients who required a PPM immediately after TAVI, and Group-2 included those patients who did not require permanent cardiac pacing at the long-term follow-up. Patients received follow-up at 1-month, 6-months, 12-months, and yearly thereafter. A total of 39 patients required a PPM immediately after TAVI (15.0%), but 178 patients (68.7%) did not. The mean follow-up was 37 ± 27 months (range 3-99 months) in both groups. There was no difference between the two groups in terms of all-cause mortality (52.6% vs. 56.8%, P = 0.125; HR 1.22 [0.87-1.77, 95% CI]), or stroke (13.3% vs. 15.1% P = 0.842; HR 1.12 [0.37-3.32, 95% CI]). However, patients who underwent PPM implantation developed an increase in readmissions for HF (21.1% vs. 31.9%, P = 0.015; HR 1.82 [1.23-3.92, 95% CI]). Conclusion: Patients requiring a PPM after TAVI did not have an increase in mortality, or an increase in the likelihood of developing a stroke at a long-term follow-up. However, this subgroup of patients showed an increase in rehospitalization due to HF at medium- and long-term follow-up.


Assuntos
Estenose da Valva Aórtica , Valva Aórtica , Estimulação Cardíaca Artificial/métodos , Próteses Valvulares Cardíacas , Substituição da Valva Aórtica Transcateter , Idoso , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/diagnóstico , Estenose da Valva Aórtica/mortalidade , Estenose da Valva Aórtica/cirurgia , Cateterismo Cardíaco/métodos , Feminino , Humanos , Masculino , Avaliação de Processos e Resultados em Cuidados de Saúde , Readmissão do Paciente/estatística & dados numéricos , Desenho de Prótese , Risco Ajustado/métodos , Espanha/epidemiologia , Tempo , Substituição da Valva Aórtica Transcateter/efeitos adversos , Substituição da Valva Aórtica Transcateter/instrumentação , Substituição da Valva Aórtica Transcateter/métodos
5.
Br J Cancer ; 110(4): 1088-100, 2014 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-24548884

RESUMO

BACKGROUND: Breast cancer is one of the most common malignancies in women. Genome-wide association studies have identified FGFR2 as a breast cancer susceptibility gene. Common variation in other fibroblast growth factor (FGF) receptors might also modify risk. We tested this hypothesis by studying genotyped single-nucleotide polymorphisms (SNPs) and imputed SNPs in FGFR1, FGFR3, FGFR4 and FGFRL1 in the Breast Cancer Association Consortium. METHODS: Data were combined from 49 studies, including 53 835 cases and 50 156 controls, of which 89 050 (46 450 cases and 42 600 controls) were of European ancestry, 12 893 (6269 cases and 6624 controls) of Asian and 2048 (1116 cases and 932 controls) of African ancestry. Associations with risk of breast cancer, overall and by disease sub-type, were assessed using unconditional logistic regression. RESULTS: Little evidence of association with breast cancer risk was observed for SNPs in the FGF receptor genes. The strongest evidence in European women was for rs743682 in FGFR3; the estimated per-allele odds ratio was 1.05 (95% confidence interval=1.02-1.09, P=0.0020), which is substantially lower than that observed for SNPs in FGFR2. CONCLUSION: Our results suggest that common variants in the other FGF receptors are not associated with risk of breast cancer to the degree observed for FGFR2.


Assuntos
Neoplasias da Mama/genética , Predisposição Genética para Doença , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/genética , Estudos de Casos e Controles , Feminino , Variação Genética , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Polimorfismo de Nucleotídeo Único/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 5 de Fator de Crescimento de Fibroblastos/genética
8.
Commun Agric Appl Biol Sci ; 75(3): 367-72, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21539255

RESUMO

In Argentina, transgenic soybean crop (Roundup Ready, RR) has undergone a major expansion over the last 15 years, with the consequent increase of glyphosate applications, a broad-spectrum and post emergence herbicide. Soybean crops are inhabited by several arthropods. Eriopis connexa Germar (Coleoptera: Coccinelidae) is a predator associated to soybean soft-bodies pest and have a Neotropical distribution. Nowadays, it is being considered a potentially biological control agent in South America. The objectives of this work were to evaluate the side-effects of glyphosate on larvae (third instar) and adults of this predator. Commercial compound and the maximum registered concentrations for field use were employed: GlifoGlex 48 (48% glyphosate, 192 mg a.i./litre, Gleba Argentina S.A.). The exposure was by ingestion through the treated prey (Rophalosiphum padi) or by drinking treated water during 48 h for treatment of the adult. The herbicide solutions were prepared using distilled water as solvent. The bioassays were carried out in the laboratory under controlled conditions: 23 +/- 0.5 degrees C, 75 +/- 5% RH and 16:8 (L:D) of photoperiod. Development time, weight of pupae, adult emergence, pre-oviposition period, fecundity and fertility were evaluated as endpoints. Larvae from glyphosate treatment molted earlier than controls. In addition, the weight of pupae, longevity, fecundity and fertility were drastically reduced in treated organisms. The reductions were more drastic when the treatments were performed at the third larval stage than as adult. The reproduction capacity of the predator was the most affected parameter and could be related to a hormonal disruption by glyphosate in the treated organisms. This work can confirm the deleterious effects of this herbicide on beneficial organisms. Also, it agrees with prior studies carried out on other predators associated to soybean pest, such as Chrysoperla externa (Neuroptera: Chrysopidae) and Alpaida veniliae (Araneae: Araneidae).


Assuntos
Besouros/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Animais , Glicina/toxicidade , Larva/efeitos dos fármacos , Óvulo/efeitos dos fármacos , Controle Biológico de Vetores , Plantas Geneticamente Modificadas , Glycine max/efeitos dos fármacos , Glycine max/genética , Glifosato
9.
Commun Agric Appl Biol Sci ; 75(3): 373-8, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21539256

RESUMO

The integrated pest management (IPM) premises claim for a joint use of beneficial organisms (parasitoids and predators) and selective pesticides. Botanical pesticides are being considered as selective pesticides. During the last 20 years of the 20th century, the plant family Meliaceae was identified as a promising source of compounds with insect-control properties. The Chinaberry tree, Melia azedarach L., is a deciduous tree native to Persia, India, and China, but has been cultivated in many countries including Africa, Australia, and the Americas. It is a source of tetranortriterpenoid compounds called meliatoxins, which have similar structures and insecticidal activities compared to azadirachtin. Eriopis connexa Germar (Coleoptera: Coccinelidae) is a native predator from the Neotropical Region. It is a beneficial organism associated to several agro-ecosystems, feeding on soft-bodies pest such as aphids, whiteflies and thrips. In horticultural crops, it has been observed to feed on worldwide important pest such as Bemisia tabaci Gennadius (Heteroptera: Aleyrodeidae) and Myzus persicae L. (Heteroptera: Aphididae), both of them considered as virus vectors. The objectives of this work were to evaluate the side-effects of M. azaderach (Meliaceas) extract on eggs, larvae and adults of Eriopis connexa. Extracts from unripe fruits (1%, w/w, obtained by the CEPROCOR, Cordoba-Argentina) were employed for ecotoxicological bioassays. The exposure method was by immersion for eggs and by ingestion of drinking water for adults. The botanical extract solutions were prepared using distilled water as solvent and a tensioactive (Tween 20) for topical application. The bioassays were carried out in the laboratory under controlled conditions: 23 +/- 0.5 degrees C temperature, 75 +/- 5% RH and 16:8 (L:D) photoperiod. Hatching, development time, adult emergence, pre-oviposition period, fecundity and fertility were evaluated as endpoints. No detrimental effects were observed in treated organisms irrespective of the exposure way and development stage. According to these preliminary results, M. azaderach fruit extracts can be compatible with E. connexa for pest control. However, future studies should be addressed to conclude about its toxicity on beneficial organisms.


Assuntos
Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Melia azedarach/química , Extratos Vegetais/química , Extratos Vegetais/toxicidade , Animais , Inseticidas/química , Óvulo/efeitos dos fármacos , Controle Biológico de Vetores/métodos
10.
Mol Neurodegener ; 15(1): 29, 2020 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-32448329

RESUMO

Huntington's disease (HD) is an incurable neurodegenerative disorder caused by CAG trinucleotide expansions in the huntingtin gene. Markers of both systemic and CNS immune activation and inflammation have been widely noted in HD and mouse models of HD. In particular, elevation of the pro-inflammatory cytokine interleukin-6 (IL-6) is the earliest reported marker of immune activation in HD, and this elevation has been suggested to contribute to HD pathogenesis. To test the hypothesis that IL-6 deficiency would be protective against the effects of mutant huntingtin, we generated R6/2 HD model mice that lacked IL-6. Contrary to our prediction, IL-6 deficiency exacerbated HD-model associated behavioral phenotypes. Single nuclear RNA Sequencing (snRNA-seq) analysis of striatal cell types revealed that IL-6 deficiency led to the dysregulation of various genes associated with synaptic function, as well as the BDNF receptor Ntrk2. These data suggest that IL-6 deficiency exacerbates the effects of mutant huntingtin through dysregulation of genes of known relevance to HD pathobiology in striatal neurons, and further suggest that modulation of IL-6 to a level that promotes proper regulation of genes associated with synaptic function may hold promise as an HD therapeutic target.


Assuntos
Encéfalo/metabolismo , Doença de Huntington/metabolismo , Interleucina-6/deficiência , Fenótipo , Animais , Encéfalo/fisiopatologia , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Doença de Huntington/genética , Interleucina-6/metabolismo , Camundongos Transgênicos
11.
Neuron ; 107(5): 891-908.e8, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32681824

RESUMO

The mechanisms by which mutant huntingtin (mHTT) leads to neuronal cell death in Huntington's disease (HD) are not fully understood. To gain new molecular insights, we used single nuclear RNA sequencing (snRNA-seq) and translating ribosome affinity purification (TRAP) to conduct transcriptomic analyses of caudate/putamen (striatal) cell type-specific gene expression changes in human HD and mouse models of HD. In striatal spiny projection neurons, the most vulnerable cell type in HD, we observe a release of mitochondrial RNA (mtRNA) (a potent mitochondrial-derived innate immunogen) and a concomitant upregulation of innate immune signaling in spiny projection neurons. Further, we observe that the released mtRNAs can directly bind to the innate immune sensor protein kinase R (PKR). We highlight the importance of studying cell type-specific gene expression dysregulation in HD pathogenesis and reveal that the activation of innate immune signaling in the most vulnerable HD neurons provides a novel framework to understand the basis of mHTT toxicity and raises new therapeutic opportunities.


Assuntos
Proteína Huntingtina/imunologia , Doença de Huntington/imunologia , Imunidade Inata/imunologia , Neurônios/imunologia , RNA Mitocondrial/imunologia , Animais , Humanos , Proteína Huntingtina/genética , Doença de Huntington/genética , Doença de Huntington/patologia , Camundongos , Mutação , Neurônios/patologia , Transcriptoma
12.
Neuron ; 106(1): 76-89.e8, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32004439

RESUMO

Unbiased in vivo genome-wide genetic screening is a powerful approach to elucidate new molecular mechanisms, but such screening has not been possible to perform in the mammalian central nervous system (CNS). Here, we report the results of the first genome-wide genetic screens in the CNS using both short hairpin RNA (shRNA) and CRISPR libraries. Our screens identify many classes of CNS neuronal essential genes and demonstrate that CNS neurons are particularly sensitive not only to perturbations to synaptic processes but also autophagy, proteostasis, mRNA processing, and mitochondrial function. These results reveal a molecular logic for the common implication of these pathways across multiple neurodegenerative diseases. To further identify disease-relevant genetic modifiers, we applied our screening approach to two mouse models of Huntington's disease (HD). Top mutant huntingtin toxicity modifier genes included several Nme genes and several genes involved in methylation-dependent chromatin silencing and dopamine signaling, results that reveal new HD therapeutic target pathways.


Assuntos
Sobrevivência Celular/genética , Proteína Huntingtina/genética , Doença de Huntington/genética , Neostriado/metabolismo , Neurônios/metabolismo , Animais , Comportamento Animal , Sistemas CRISPR-Cas , Técnicas de Silenciamento de Genes , Biblioteca Gênica , Genes Essenciais/genética , Camundongos , Camundongos Transgênicos , Nucleosídeo NM23 Difosfato Quinases/genética , Nucleosídeo Difosfato Quinase D/genética , Agregados Proteicos , Interferência de RNA , RNA Guia de Cinetoplastídeos , RNA Interferente Pequeno , Receptores de Dopamina D2/genética , Análise de Sequência de RNA
13.
Forensic Sci Med Pathol ; 5(2): 95-9, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19412674

RESUMO

In this paper, we describe a forensic paleopathology case using findings obtained from images of a skull with leontiasis ossea. This unique specimen is on display in the National Museum of Anthropology and History in Mexico. The skull shows tissue overgrowth, periosteal bone proliferation, which produced a cortical and diploid thickening involving the entire bone matrix. The study of images, X-rays, and helical computed tomography revealed generalized hyperostosis obliterating the maxillary and sphenoid sinuses, and two exuberant bony masses arising from the maxilla with encroachment of the anterior nasal opening. In order to reconstruct an image of the external appearance in life, a copy was obtained in the first place, using a stereolithography machine, after that, three-dimensional (3-D) facial reconstruction technique was applied, thus an approximation of the external appearance of this specimen was obtained. During the process, we encountered several difficulties, mainly when interpreting the cortical topography, the position of eyes and mouth. In this sense, facial reconstruction allows only for a moderate investigation due to the limited information that can be obtained from the skull and the significant alterations observed.


Assuntos
Face/anatomia & histologia , Antropologia Forense/métodos , Hiperostose Frontal Interna/patologia , Crânio/anormalidades , Cefalometria , Feminino , Humanos , Imageamento Tridimensional , Paleopatologia , Tomografia Computadorizada por Raios X
14.
Commun Agric Appl Biol Sci ; 74(1): 117-23, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-20218517

RESUMO

Optical brighteners have attracted interest as adjuvant's in baculovirus-based biological insecticides due to their ability enhance the insecticidal properties of these viruses and protect virus particles from the degrading effects of ultraviolet (UV) radiation. The effects of two types of optical brighteners, Tinopal CBS (a distyryl-biphenyl derivative) and Tinopal C1101 (an ethenediyl benzenesulfonic derivative) at 1 or 3% (wt./vol.), on growth of different crOPs [maize, Zea mays L. (var. HY-311), sorghum, Sorghum vulgare Pers. (var. Silo), tomato, Lycopersicum esculentum L. (var. Floradade IT), or pepper, Capsicum annum L. (var. Cal Won 300)] were examined after once a week application during four weeks. Both compounds significantly affected the growth of maize plants, whereas sorghum plants were affected only at the highest concentration of Tinopal C1101. Neither brightener had negative effects on tomato or peppers plants. Both compounds increased the percentage of reflectance of maize and tomato leaves when analyzed using laboratory and field spectrophotometers. A greenhouse experiment involving single application of 1 and 3% Tinopal C1101 indicated that the stomatal conductance and photosynthetic rate of maize and tomato plants were not significantly affected. We conclude that the effects of optical brighteners on plant growth are more likely to be influenced by differences between plant species than differences between brightener compounds.


Assuntos
Adjuvantes Farmacêuticos/farmacologia , Agricultura/métodos , Produtos Agrícolas/efeitos dos fármacos , Controle Biológico de Vetores/métodos , Praguicidas/química , Praguicidas/farmacologia , Adjuvantes Farmacêuticos/química , Benzenossulfonatos , Relação Dose-Resposta a Droga , Fotossíntese/efeitos dos fármacos , Estômatos de Plantas/efeitos dos fármacos
15.
Commun Agric Appl Biol Sci ; 74(2): 425-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-20222601

RESUMO

Methoxyfenozide is an ecdysone agonist, the most new class of insect growth regulators. Most studies of the toxicity of ecdysone agonists on lepidopteran pests have been conducted during the larval stages, and little has been published regarding its sublethal effects in the surviving individuals. In this study, the lethal and sublethal effects of methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) were assessed. For this, fifth instars of this pest were continuously fed, until pupation, with artificial diet containing 0.24 and 0.35 mg of active ingredient/kg diet, which correspond to the LC10 and LC25 values, respectively, for this insecticide. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC10 and 60% for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. Both male and female treated larvae lived about seven days longer than the controls for both concentrations tested. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm.


Assuntos
Hidrazinas/toxicidade , Hormônios Juvenis/toxicidade , Larva/efeitos dos fármacos , Spodoptera/efeitos dos fármacos , Spodoptera/crescimento & desenvolvimento , Zea mays/parasitologia , Ração Animal/toxicidade , Animais , Dinâmica Populacional , Testes de Toxicidade
16.
Rev Sci Instrum ; 90(2): 026102, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30831743

RESUMO

The measurement of surface photovoltage (SPV) transients over 12 orders of magnitude in time was recently demonstrated [Rev. Sci. Instrum. 88, 053904 (2017)]. In dedicated experiments, however, a high-impedance buffer shall be placed outside the measurement chamber, which has consequences for SPV measurements at very short times. By varying the LCR circuit of a measurement configuration, applying a multi-parameter fit and simulating the corresponding SPV transients, we show, on the examples of highly doped silicon and a CdS thin film, that the source function of SPV transients can be reconstructed with a resolution time better than 1 ns.

17.
Commun Agric Appl Biol Sci ; 72(3): 543-7, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18399486

RESUMO

Baculoviruses are arthropod-specific viruses currently used as biological insecticides in several countries of the world. One important factor limiting the efficacy of these bioinsecticides is related to the inactivation of the virus by solar ultraviolet (UV) radiation. This has motivated studies focused on the use of optical brightener compounds that can protect the virus from UV inactivation. The effects of the optical brightener Tinopal C1101 (ethenedyl benzenesulfonic derivative) on the persistance of a nucleopolyhedrovirus (SfMNPV) was quantified in third instar Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), the principal pest of maize in the Americas. For this, laboratory studies were performed to determine the relationship between virus concentrations and radiation-caused inactivation of SfMNPV alone or in mixtures with 1.25 or 0.1% (vol/vol) Tinopal C1101 using a UV system [radiation was provided by a 15 W UV tube (emission maxima at 312 nm)]. SfMNPV alone was more sensitive to UV than in mixtures with 1.25 or 0.1% Tinopal C1101. For instance, at concentrations of 2.22 x 10(8) and 2.75 x 10(6) occlusion bodies (OBs)/ml, SfMNPV alone-caused mortality was reduced from 88 and 44% (without UV radiation) to 0%, in both cases, after 30 and 15 min exposure to the UV tube, respectively. In contrast, the incorporation of 1.25% Tinopal C1101 into the SfMNPV inoculum at 2.22 x 10(8) and 2.75 x 10(6) OBs/ml caused a mortality of 86.6 and 96.6% after 240 min, respectively. UV-caused inactivation of SfMNPV was directly related to the optical brightener concentration. We conclude that optical brighteners are likely to represent valuable components of nucleopolyhedrovirus formulations.


Assuntos
Benzenossulfonatos/farmacologia , Nucleopoliedrovírus/efeitos da radiação , Spodoptera/virologia , Raios Ultravioleta , Zea mays/parasitologia , Animais , Relação Dose-Resposta a Droga , Relação Dose-Resposta à Radiação , Nucleopoliedrovírus/fisiologia , Controle Biológico de Vetores/métodos , Luz Solar
18.
Commun Agric Appl Biol Sci ; 72(3): 557-9, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18399488

RESUMO

Spiders are important predators of several agricultural pests and they play an important role as indicators of ecosystem disturb. In Argentina, soybean crop has increased from the introduction of transgenic soybean resistant to glyphosate. This expansion produced an increase in the use of conventional and non-selective pesticides to control soybean pests. The objective of this work was to evaluate the side effects of subletal concentrations of two neurotoxican insecticides with a different mode of action: endosulfan (Glex, 35%, 25 mg/l a.i.) and spinosad (Tracer, 48%, 30 and 3 mg/l a.i) on Araneus pratensis. The insecticides were applied by ingestion of the treated prey (Musca domestica), and the effects on mortality, prey consumption, web building, mating, ootheca construction and fecundity were determined. Spinosad (30 mg/l a.i.) produced higher mortality than endosulfan (25 mg/l a.i.). Tremors and non-coordinated movements were observed in this treatment. The prey consumption was significantly reduced by the two insecticides (approximately 40% lower than control). The spider web building was significantly affected by the two insecticides, but spinosad had a greater effect. Though mating was not affected by both pesticides, abnormal oothecas and dehydrated eggs were observed. This work reports that sublethal concentrations representing approximately from 25 to 2.5% of the maximum field recommended concentrations (105 and 120 mg/l a.i., respectively) showed negative effects on A. pratensis. The consequences of these effects on role of A. pratensis as a natural mortality factor of soybean pests are discussed.


Assuntos
Cadeia Alimentar , Glycine max/parasitologia , Moscas Domésticas/química , Inseticidas/farmacologia , Aranhas/fisiologia , Animais , Argentina , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Endossulfano/farmacologia , Comportamento Alimentar , Feminino , Fertilidade/efeitos dos fármacos , Fertilidade/fisiologia , Controle de Insetos/métodos , Macrolídeos/farmacologia , Masculino , Oviposição/efeitos dos fármacos , Oviposição/fisiologia , Aranhas/efeitos dos fármacos , Aranhas/crescimento & desenvolvimento
19.
J Econ Entomol ; 110(4): 1465-1475, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28499035

RESUMO

This study describes four multiple nucleocapsid nucleopolyhedrovirus isolates recovered from infected larvae of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on crops in two different geographical regions of Mexico. Molecular and biological characterization was compared with characterized S. exigua multiple nucleopolyhedrovirus (SeMNPV) isolates from the United States (SeUS1 and SeUS2) and Spain (SeSP2). Restriction endonuclease analysis of viral DNA confirmed that all Mexican isolates were SeMNPV isolates, but molecular differences between the Mexican and the reference isolates were detected using PCR combined with restriction fragment length polymorphism (RFLP). Amplification of the variable region V01 combined with RFLP distinguished the two Mexican isolates, SeSLP6 and SeSIN6. BglII digestions showed that the majority of the isolates contained submolar bands, indicating the presence of genetic heterogeneity. Amplification of the variable regions V04 and V05 distinguished between American and the Spanish isolates. Biological characterization was performed against two laboratory colonies of S. exigua, one from Mexico, and another from Switzerland. Insects from the Mexican colony were less susceptible to infection than insects from Se-Swiss colony. In the Se-Mex colony, SeSP2 was the most pathogenic isolate followed by SeSIN6, although their virulence was similar to most of the isolates tested. In Se-Swiss colony, similar LD50 values were observed for the five isolates, although the virulence was higher for the SeSLP6 isolate, which also had the highest OB (occlusion body) yield. We conclude that the Mexican isolates SeSIN6 and SeSLP6 possess insecticidal traits of value for the development of biopesticides for the control of populations of S. exigua.


Assuntos
DNA Viral/genética , Nucleopoliedrovírus/fisiologia , Controle Biológico de Vetores , Spodoptera/virologia , Animais , Larva/crescimento & desenvolvimento , Larva/virologia , México , Nucleopoliedrovírus/genética , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Spodoptera/crescimento & desenvolvimento
20.
J Exp Psychol Anim Behav Process ; 26(2): 144-56, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10782430

RESUMO

Conditioning-specific reflex modification (CRM) occurs when classical conditioning modifies responding to an unconditioned stimulus (US) in the absence of a conditioned stimulus (CS). Three experiments monitored rabbit nictitating (Oryctolagus cuniculus) membrane unconditioned responses to 5 intensities and 4 durations of periorbital electrical stimulation before and after CS or US manipulation. CRM occurred after 12 days of CS-US pairings but not following unpaired CS/US presentations or restraint. CRM survived CS-alone and CS/US-unpaired extinction of the conditioned response (CR) but not presentations of the US alone, although CRs remained intact. Thus, CRs could be weakened without eliminating CRM and CRM could be weakened without eliminating CRs. Data indicate CRM is a reliable, associative effect that is more than a generalized CR and may not be explained by habituation, stimulus generalization, contextual conditioning, or bidirectional conditioning.


Assuntos
Condicionamento Psicológico/fisiologia , Doenças Palpebrais/veterinária , Membrana Nictitante/fisiologia , Adaptação Fisiológica/fisiologia , Animais , Estimulação Elétrica/métodos , Masculino , Coelhos , Distribuição Aleatória , Reflexo/fisiologia
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