Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
1.
Gynecol Obstet Fertil Senol ; 46(10-11): 686-691, 2018 11.
Artigo em Francês | MEDLINE | ID: mdl-30293947

RESUMO

OBJECTIVES: Operative Vaginal Delivery (OVD) is subject to a risk of perineal tears especially of Obstetrical Anal Sphincter Injuries (OASIS) that are associated with more complications and impaired quality of life. The main objective of this study was to compare the rate of OASIS in primipara at term with fetus in cephalic presentation depending on the type of delivery: OVD using vacuum extractor and spontaneous delivery. METHODS: This is a single-center retrospective study between 01/01/2010 and 12/31/2014 including all primipara who delivered vaginally at term, a single and living fetus in cephalic presentation. Perineal lesions were classified according to the WHO classification. The primary endpoint was the proportion of OASIS. RESULTS: 3552 patients were included: 2496 spontaneous deliveries (SD) and 1056 OVD (29.72 %). There were twenty sphincter tears (0.56 %): 7 in SD group (0.28 %) and 13 in OVD (1.23 %), P<0.0001, OR=5.10 [2.00; 12.99]. Other risk factors associated with OASIS in univariable analysis were: maternal age (≥30 years), duration of expulsive efforts (≥20min) and a birth weight≥4000g. CONCLUSION: In these patients, the risk of OASIS in case of AI increases by a factor of 5;10. The high rate of AI in these patients exposes them to a real risk of OASIS. However, the proportion of OASIS in this group remains lower than those reported in the literature and is barely higher than the national overall rate, despite a very restrictive policy of the use of episiotomy.


Assuntos
Canal Anal/lesões , Paridade , Vácuo-Extração/efeitos adversos , Adulto , Parto Obstétrico/métodos , Feminino , Humanos , Lacerações/epidemiologia , Gravidez , Estudos Retrospectivos , Fatores de Risco , Nascimento a Termo
2.
Neurologia ; 32(4): 241-252, 2017 May.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-25529181

RESUMO

BACKGROUND: Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. DEVELOPMENT: This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). CONCLUSIONS: Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments.


Assuntos
Ataxia/genética , Proteína do X Frágil da Deficiência Intelectual/genética , Proteína do X Frágil da Deficiência Intelectual/farmacologia , Síndrome do Cromossomo X Frágil/genética , Tremor/genética , Ataxia/diagnóstico , Transtorno Autístico , Síndrome do Cromossomo X Frágil/diagnóstico , Humanos , Deficiência Intelectual , Mutação/genética , RNA Mensageiro , Tremor/diagnóstico
3.
Biomed Res Int ; 2016: 4521767, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27294119

RESUMO

Introduction. Manikin-based studies for evaluation of ventilation performance show high heterogeneity in the analysis and experimental methods used as we pointed out in previous studies. In this work, we aim to evaluate these potential limitations and propose a new analysis methodology to reliably assess ventilation performance. Methods. One hundred forty healthcare providers were selected to ventilate a manikin with two adult self-inflating bags in random order. Ventilation parameters were analysed using different published analysis methods compared to ours. Results. Using different methods impacts the evaluation of ventilation efficiency which ranges from 0% to 45.71%. Our new method proved relevant and showed that all professionals tend to cause hyperventilation and revealed a significant relationship between professional category, grip strength of the hand keeping the mask, and ventilation performance (p = 0.0049 and p = 0.0297, resp.). Conclusion. Using adequate analysis methods is crucial to avoid many biases. Extrapolations to humans still have to be taken with caution as many factors impact the evaluation of ventilation performance. Healthcare professionals tend to cause hyperventilation with current devices. We believe this problem could be prevented by implementing monitoring tools in order to give direct feedback to healthcare professionals regarding ventilation efficiency and ventilatory parameter values.


Assuntos
Manequins , Respiração Artificial/instrumentação , Adulto , Algoritmos , Feminino , Força da Mão , Humanos , Hiperventilação/etiologia , Hiperventilação/prevenção & controle , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Respiração Artificial/efeitos adversos , Respiração Artificial/métodos
5.
J Eur Acad Dermatol Venereol ; 28(12): 1816-20, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24206262

RESUMO

BACKGROUND: Tumour necrosis factor alpha (TNF-α) inhibitors are associated with an increased risk of infections and with a still debatable risk of skin cancer. Furthermore, cutaneous human papillomavirus (HPV) infection may be involved in skin cancer. OBJECTIVES: Our primary objective was to assess the HPV DNA prevalence in psoriasis patients treated with TNF inhibitors and the secondary objective was to assess the same parameter before and during treatment. METHODS: Plucked eyebrow hairs were collected from 151 consecutive patients with moderate to severe chronic plaque psoriasis, including 48 patients treated with anti-TNF-α agents, 21 patients treated with methotrexate (MTX) and 82 patients with no previous systemic treatment. Among them, 38 patients were subsequently treated with either MTX or anti-TNF-α agents. HPV genotyping was performed using the HPV type-specific E7 PCR bead-based multiplex allowing the detection of 27 genus-α types, 25 genus-ß types, 16 genus-γ types and one single genus-µ type. Follow-up provided a total of 972.7 person-months of overall exposure for patients treated with TNF inhibitors and 326.9 person-months for patients treated with MTX. RESULTS: Our data confirm the high prevalence of ß-HPV infection in healthy skin of psoriasis patients (68.9%), with no significant difference between untreated patients (64.6%), patients treated with MTX (76.2%) and patients treated with anti-TNF-α agents (72.9%). The mean number of different HPV types and the distribution of HPV types were similar in different groups of patients. Moreover, in prospectively treated patients, we did not observe any change in the HPV DNA prevalence in the distribution of HPV types and the number of HPV types after a mean duration of treatment of 332 ± 39.8 days. CONCLUSION: Despite the small number of patients in our cohort, our results are quite encouraging in view of the increased use of anti-TNF-α agents in different auto inflammatory immune diseases.


Assuntos
DNA Viral/análise , Sobrancelhas , Cabelo/química , Papillomaviridae/genética , Psoríase/tratamento farmacológico , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Humanos , Psoríase/fisiopatologia
6.
Clin Genet ; 86(4): 378-82, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24028275

RESUMO

Carriers of an FMR1 premutation allele (55-200 CGG repeats) often develop the neurodegenerative disorders, fragile X-associated tremor/ataxia syndrome (FXTAS). Neurological signs of FXTAS, parkinsonism and rapid onset of cognitive decline have not been reported in individuals with an unmethylated full mutation (FM). Here, we report a Chilean family affected with FXS, inherited from a parent carrier of an FMR1 unmethylated full mosaic allele, who presented with a fast progressing FXTAS. This case suggests that the definition of FXTAS may need to be broadened to not only include those with a premutation but also those with an expanded allele in FM range with a lack of methylation leading to elevated FMR1-mRNA expression levels and subsequent RNA toxicity.


Assuntos
Ataxia/genética , Metilação de DNA/genética , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Tremor/genética , Idoso , Ataxia/complicações , Ataxia/patologia , Chile , Síndrome do Cromossomo X Frágil/complicações , Síndrome do Cromossomo X Frágil/patologia , Humanos , Masculino , Mosaicismo , Tremor/complicações , Tremor/patologia
7.
Rev. chil. neuro-psiquiatr ; 46(4): 280-287, dic. 2008. tab
Artigo em Espanhol | LILACS | ID: lil-547790

RESUMO

Frontotemporal dementia is a neurodegenerative condition that presents with a number of distinct behavioral phenotypes. One of them is semantic dementia (SD), where exists a profound impairment for semantic knowledge related to atrophy of temporal poles. Pathologically, in most cases positive intraneuronal ubiquitin and tau negative inclusions are observed. SD is characterized by fluent, effortless, grammatical speech which lacks informational content, with limited and repetitive content, as well as semantic paraphasias. Also, patients may present with associative visual agnosia, surface dyslexia or dysgraphia, behavioral alterations. Both episodic and autobiographical memory are close to normality. Two female patients with fluent progressive aphasia are reported; they failed in a simple test of semantic association (to point to one of four objects with lesser relation to others). Autobiographical memory was fair. SD can be wrongly diagnosed as left-sided variant of Alzheimer's disease; absence of episodic amnesia and parietal defects may be useful for clinical diagnosis.


La demencia semántica es una variante de las atrofias lobares frontotemporales que se caracteriza por la degradación del conocimiento semántico, de los conceptos. En ella existe una atrofia predominante de los polos temporales, a veces asimétrica; la patología generalmente muestra neuronas con inclusiones ubiquitina (+) y tau (-). Se expresa como una afasia progresiva fluente, sin disartria ni agramatismo, con anomia y parafasias verbales o semánticas, poco informativa. Pueden existir agnosia visual asociativa y alteraciones conductuales; a veces existen alexia y/o agrafía de superficie. Hay respeto relativo de la memoria episódica y autobiográfica. Se presentan dos mujeres con afasia progresiva fluente, alteraciones conductuales y falla en una tarea semántica (4º excluido). A pesar de estos defectos la memoria autobiográfica y el desempeño en sus actividades cotidianas estaban dentro de lo normal. Se concluye que estos cuadros deben diferenciarse de los casos de enfermedad de Alzheimer de predominio izquierdo; el respeto de la memoria episódica y la falta de compromiso parietal descartarían clínicamente esta última patología.


Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Demência/diagnóstico , Demência/fisiopatologia , Semântica , Comportamento Verbal , Afasia , Lobo Frontal/fisiopatologia
8.
Mol Plant Microbe Interact ; 21(2): 232-43, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18184067

RESUMO

Sulfated laminarin (PS3) has been shown previously to be an elicitor of plant defense reactions in tobacco and Arabidopsis and to induce protection against tobacco mosaic virus. Here, we have demonstrated the efficiency of PS3 in protecting a susceptible grapevine cultivar (Vitis vinifera cv. Marselan) against downy mildew (Plasmopara viticola) under glasshouse conditions. This induced resistance was associated with potentiated H2O2 production at the infection sites, upregulation of defense-related genes, callose and phenol depositions, and hypersensitive response-like cell death. Interestingly, similar responses were observed following P. viticola inoculation in a tolerant grapevine hybrid cultivar (Solaris). A pharmacological approach led us to conclude that both callose synthesis and jasmonic acid pathway contribute to PS3-induced resistance.


Assuntos
Glucanos/farmacologia , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/imunologia , Oomicetos/fisiologia , Doenças das Plantas/imunologia , Vitis/imunologia , Vitis/microbiologia , Morte Celular/efeitos dos fármacos , Ciclopentanos/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Peróxido de Hidrogênio/metabolismo , Oomicetos/citologia , Oomicetos/crescimento & desenvolvimento , Oomicetos/ultraestrutura , Oxilipinas/farmacologia , Doenças das Plantas/microbiologia , Folhas de Planta/citologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/microbiologia , Folhas de Planta/ultraestrutura , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/microbiologia , Estômatos de Plantas/ultraestrutura , Esporos/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Vitis/citologia , Vitis/genética
9.
Rev. Hosp. Clin. Univ. Chile ; 19(3): 239-244, 2008. tab, ilus
Artigo em Espanhol | LILACS | ID: lil-530342

RESUMO

High grade gliomas are lethal cancers. Despite recent advances in surgery, radiotherapy and chemotherapy, the overall survival is 15 months for glioblastoma. They are among the most vascular of human tumors, making them especially attractive targets for angiogenesis inhibitors. Most clinical trials of these agents as monotherapy have failed to demonstrate survival benefit in unselected high grade glioma patient populations. Several mechanisms of treatment failure have been postulated. In response, there are new intervention strategies on course: the combination of target therapy with classic chemotherapy, multitargeted kinase inhibitors and combinations of single-targeted kinase inhibitors and the identification of correlative biomarkers. These advances provide real opportunities for the development of effective therapies for high grade gliomas.


Assuntos
Humanos , Masculino , Feminino , Glioma/classificação , Glioma/terapia , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/uso terapêutico , Astrocitoma , Neoplasias Encefálicas
10.
Ultramicroscopy ; 100(3-4): 171-8, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15231307

RESUMO

Despite cell wall reinforcement being a well-known defence mechanism of plants, it remains poorly characterized from a physical point of view. The objective of this work was to further describe this mechanism. Vitis vinifera cv Gamay cells were treated with UV-light (254 nm), a well-known elicitor of defence mechanisms in grapevines, and physical cell wall modifications were observed using the atomic force microscopy (AFM) under native conditions. The grapevine cell suspensions were continuously observed in their culture medium from 30 min to 24h after elicitation. In the beginning, cellulose fibrils covered by a matrix surrounded the control and treated cells. After 3 h, the elicited cells displayed sprouted expansions around the cell wall that correspond to pectin chains. These expansions were not observed on untreated grapevine cells. The AFM tip was used to determine the average surface elastic modulus of cell wall that account for cell wall mechanical properties. The elasticity is diminished in UV-treated cells. In a comparative study, grapevine cells showed the same decrease in cell wall elasticity when treated with a fungal biotic elicitor of defence response. These results demonstrate cell wall strengthening by UV stress.


Assuntos
Vitis/efeitos da radiação , Parede Celular/efeitos da radiação , Parede Celular/ultraestrutura , Microscopia de Força Atômica , Raios Ultravioleta , Vitis/ultraestrutura
11.
Trends Plant Sci ; 6(4): 177-83, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11286923

RESUMO

Since its identification as an endothelium-derived relaxing factor in the 1980s, nitric oxide has become the source of intensive and exciting research in animals. Nitric oxide is now considered to be a widespread signaling molecule involved in the regulation of an impressive spectrum of mammalian cellular functions. Its diverse effects have been attributed to an ability to chemically react with dioxygen and its redox forms and with specific iron- and thiol-containing proteins. Moreover, the effects of nitric oxide are dependent on the dynamic regulation of its biosynthetic enzyme nitric oxide synthase. Recently, the role of nitric oxide in plants has received much attention. Plants not only respond to atmospheric nitric oxide, but also possess the capacity to produce nitric oxide enzymatically. Initial investigations into nitric oxide functions suggested that plants use nitric oxide as a signaling molecule via pathways remarkably similar to those found in mammals. These findings complement an emerging body of evidence indicating that many signal transduction pathways are shared between plants and animals.


Assuntos
Óxido Nítrico/fisiologia , Plantas/metabolismo , Transdução de Sinais , Aconitato Hidratase/metabolismo , Adenosina Difosfato Ribose/metabolismo , Animais , GMP Cíclico/metabolismo , Mamíferos , Óxido Nítrico/biossíntese , Óxido Nítrico/química , Óxido Nítrico Sintase/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/metabolismo
12.
Plant Physiol ; 125(2): 564-72, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11161014

RESUMO

The dynamics of microtubular cytoskeleton were studied in tobacco (Nicotiana tabacum cv Xanthi) cells in response to two different plant defense elicitors: cryptogein, a protein secreted by Phytophthora cryptogea and oligogalacturonides (OGs), derived from the plant cell wall. In tobacco plants cryptogein triggers a hypersensitive-like response and induces systemic resistance against a broad spectrum of pathogens, whereas OGs induce defense responses, but fail to trigger cell death. The comparison of the microtubule (MT) dynamics in response to cryptogein and OGs in tobacco cells indicates that MTs appear unaffected in OG-treated cells, whereas cryptogein treatment caused a rapid and severe disruption of microtubular network. When hyperstabilized by the MT depolymerization inhibitor, taxol, the MT network was still disrupted by cryptogein treatment. On the other hand, the MT-depolymerizing agent oryzalin and cryptogein had different and complementary effects. In addition to MT destabilization, cryptogein induced the death of tobacco cells, whereas OG-treated cells did not die. We demonstrated that MT destabilization and cell death induced by cryptogein depend on calcium influx and that MT destabilization occurs independently of active oxygen species production. The molecular basis of cryptogein-induced MT disruption and its potential significance with respect to cell death are discussed.


Assuntos
Proteínas de Algas/farmacologia , Citoesqueleto/ultraestrutura , Microtúbulos/ultraestrutura , Nicotiana/ultraestrutura , Cálcio/fisiologia , Bloqueadores dos Canais de Cálcio/farmacologia , Células Cultivadas , Citoesqueleto/efeitos dos fármacos , Ácido Egtázico/farmacologia , Proteínas Fúngicas , Microtúbulos/efeitos dos fármacos , Nicotiana/efeitos dos fármacos , Nicotiana/fisiologia
13.
Mol Plant Microbe Interact ; 13(8): 821-9, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10939253

RESUMO

We previously reported that the signal transduction of cryptogein, an elicitor of defense reactions in Nicotiana tabacum cells, involves upstream protein phosphorylation. In the present study, induction of these early physiological events was further investigated with inhibitors of protein phosphatase (PP), okadaic acid, and calyculin A. Calyculin A mimicked the effects of cryptogein, inducing an influx of calcium, an extracellular alkalinization, and the production of active oxygen species (AOS), suggesting that during cryptogein signal transduction the balance between specific protein kinase (PK) and PP activities was modified. To identify the phosphorylated proteins that could be involved early in the elicitor signaling pathway, we analyzed by 2-D electrophoresis the in vivo phosphorylation status of proteins after cryptogein, staurosporine, and calyculin A treatments of tobacco cells (5 min). Of about 100 phospho-labeled polypeptides, 19 showed increased 32P incorporation after 5 min of cryptogein treatment. Phosphorylation of 12 of the 19 polypeptides depended upon calcium influx. Staurosporine inhibited the phosphorylations induced by cryptogein whereas calyculin A activated the phosphorylation of 18 of these polypeptides. This study highlighted the role of PKs and/or constitutive active PPs whose activation and inhibition, respectively, resulted in an increased phosphorylation of proteins that may be involved in cryptogein signal transduction. Identification of the phosphoproteins is in progress and will increase our knowledge of signal transduction pathways implicated in plant defense responses.


Assuntos
Proteínas de Algas , Proteínas Fúngicas/metabolismo , Nicotiana/fisiologia , Fosfoproteínas/fisiologia , Plantas Tóxicas , Transdução de Sinais/fisiologia , Cálcio/metabolismo , Inibidores Enzimáticos/farmacologia , Transporte de Íons , Fosfoproteínas Fosfatases/antagonistas & inibidores , Fosforilação , Inibidores de Proteínas Quinases
14.
J Biol Chem ; 274(49): 34699-705, 1999 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-10574936

RESUMO

Cryptogein is a 98-amino acid proteinaceous elicitor of tobacco defense reactions. Specific binding of cryptogein to high affinity binding sites on tobacco plasma membranes has been previously reported (K(d) = 2 nM; number of binding sites: 220 fmol/mg of protein). In this study, biochemical characterization of cryptogein binding sites reveals that they correspond to a plasma membrane glycoprotein(s) with an N-linked carbohydrate moiety, which is involved in cryptogein binding. Radiation inactivation experiments performed on tobacco plasma membrane preparations indicated that cryptogein bound specifically to a plasma membrane component with an apparent functional molecular mass of 193 kDa. Moreover, using the homobifunctional cross-linking reagent disuccinimidyl suberate and tobacco plasma membranes incubated with (125)I-cryptogein, we identified, after SDS-polyacrylamide gel electrophoresis and autoradiography, two (125)I-cryptogein linked N-glycoproteins of about 162 and 50 kDa. Similar results were obtained using Arabidopsis thaliana and Acer pseudoplatanus plasma membrane preparations, whereas cryptogein did not induce any effects on the corresponding cell suspensions. These results suggest that either cryptogein binds to nonfunctional binding sites, homologues to those present in tobacco plasma membranes, or that a protein involved in signal transduction after cryptogein recognition is absent or inactive in both A. pseudoplatanus and A. thaliana.


Assuntos
Proteínas de Algas , Arabidopsis/química , Proteínas de Bactérias , Sítios de Ligação , Proteínas Fúngicas/química , Proteínas de Membrana/química , Proteínas de Plantas/química , Arabidopsis/metabolismo , Toxinas Bacterianas/farmacologia , Ligação Competitiva , Membrana Celular/química , Membrana Celular/metabolismo , Reagentes de Ligações Cruzadas/metabolismo , Proteínas Fúngicas/isolamento & purificação , Glicosídeo Hidrolases/metabolismo , Cinética , Proteínas de Membrana/metabolismo , Ácido Periódico/metabolismo , Proteínas de Plantas/metabolismo , Plantas Tóxicas , Ligação Proteica , Fatores de Tempo , Nicotiana/metabolismo
15.
Biochimie ; 81(6): 663-8, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10433120

RESUMO

Cryptogein, a 98 amino acid protein secreted by the fungus Phytophthora cryptogea, induces a hypersensitive response and systemic acquired resistance in tobacco plants (Nicotiana tabacum var Xanthi). The mode of action of cryptogein has been studied using tobacco cell suspensions. The recognition of this elicitor by a plasma membrane receptor leads to a cascade of events including protein phosphorylation, calcium influx, potassium and chloride effluxes, plasma membrane depolarization, activation of a NADPH oxidase responsible for active oxygen species (AOS) production and cytosol acidification, activation of the pentose phosphate pathway, and activation of two mitogen-activated protein kinase (MAPK) homologues. The organization of the cryptogein responses reveals that the earliest steps of the signal transduction pathway involve plasma membrane activities. Their activation generates a complex network of second messengers which triggers the specific physiological responses. This study may contribute to our understanding of plant signaling processes because elicitors and a variety of signals including hormones, Nod factors, light, gravity and stresses share some common transduction elements and pathways.


Assuntos
Proteínas de Algas , Proteínas Fúngicas/metabolismo , Proteínas de Membrana/metabolismo , Nicotiana/metabolismo , Proteínas de Plantas/metabolismo , Plantas Tóxicas , Transdução de Sinais , Animais , Membrana Celular/metabolismo , Nicotiana/imunologia
16.
Plant Physiol ; 118(4): 1317-26, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9847105

RESUMO

Elicitins are a family of small proteins secreted by Phytophthora species that have a high degree of homology and elicit defense reactions in tobacco (Nicotiana tabacum). They display acidic or basic characteristics, the acidic elicitins being less efficient in inducing plant necrosis. In this study we compared the binding properties of four elicitins (two basic and two acidic) and early-induced signal transduction events (Ca2+ influx, extracellular medium alkalinization, and active oxygen species production). The affinity for tobacco plasma membrane-binding sites and the number of binding sites were similar for all four elicitins. Furthermore, elicitins compete with one another for binding sites, suggesting that they interact with the same receptor. The four elicitins induced Ca2+ influx, extracellular medium alkalinization, and the production of active oxygen species in tobacco cell suspensions, but the intensity and kinetics of these effects were different from one elicitin to another. As a general observation the concentrations that induce similar levels of biological activities were lower for basic elicitins (with the exception of cinnamomin-induced Ca2+ uptake). The qualitative similarity of early events induced by elicitins indicates a common transduction scheme, whereas fine signal transduction tuning is different in each elicitin.

17.
Plant J ; 15(6): 773-81, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9807816

RESUMO

Elicitors of plant defence reactions (such as cryptogein, an elicitin produced by Phytophthora cryptogea, or oligogalacturonides (OGs)), induced in tobacco cell suspensions (Nicotiana tabacum var Xanthi) a rapid and transient activation of two protein kinases (PKs) with apparent molecular masses of 50 and 46 kDa, respectively. These PKs activated and phosphorylated at tyrosine residues, phosphorylated myelin basic protein (MBP) at serine/threonine residues. Both are recognized by anti-MAPK antibodies. The two MBP kinases possessed the same kinetics of activation, and their activation depended, to the same extent, on different exogenously applied compounds (staurosporine, lanthanum, EGTA). We demonstrate here that the activation of the MBP kinases is calcium dependent and sensitive to staurosporine, a protein kinase inhibitor which annihilates all known responses of tobacco cells to cryptogein. The activation of MBP kinases appeared to be independent of the production of active oxygen species (AOS) and insensitive to calyculin A, a protein phosphatase type 1 and 2A inhibitor. The activation of MAPKs is discussed in relation to the early responses induced by cryptogein.


Assuntos
Proteínas de Algas , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Nicotiana/química , Plantas Tóxicas , Cálcio/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/química , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Proteínas Fúngicas/farmacologia , Quinase 3 da Glicogênio Sintase , Fosforilação , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Estaurosporina/farmacologia , Tirosina/metabolismo
18.
Plant Mol Biol ; 35(3): 261-9, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9349250

RESUMO

We report the successful combination of mRNA differential-display reverse-transcription PCR (DDRT-PCR) and 5'-rapid amplification of cDNA ends (5'-RACE) in order to isolate full-length cDNAs corresponding to genes activated in tobacco cells treated with cryptogein within 60 min. Cloning and sequencing of two cDNAs, called 'tcI 7' and 'tcI 14' (for tobacco cryptogein-induced), allowed the identification of open reading frames. Deduced amino-acid sequences of 'tcI 7' and 'tcI 14' showed significant homologies with a beta-type proteasome subunit and a transformer-2-like serine/arginine-rich (SR) ribonucleoprotein, respectively. The accumulation of mRNAs corresponding to 'tcI 7' started 30 min after the addition of cryptogein to tobacco cell suspensions and continued up to 180 min, whereas the accumulation of 'tcI 14' corresponding mRNAs was transitory between 30 and 60 min. These results indicated a transcriptional activation of the corresponding genes early after elicitation of tobacco cells by cryptogein. The biological significance of this activation remains to be elucidated.


Assuntos
Proteínas de Algas , Cisteína Endopeptidases/genética , DNA Complementar/isolamento & purificação , Proteínas de Drosophila , Proteínas Fúngicas/farmacologia , Genes de Plantas , Complexos Multienzimáticos/genética , Proteínas Nucleares/genética , Fosfoproteínas/genética , Ribonucleoproteínas/genética , Sequência de Aminoácidos , Animais , Arginina , Sequência de Bases , Clonagem Molecular , DNA Complementar/química , Drosophila , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/efeitos dos fármacos , Dados de Sequência Molecular , Proteínas Nucleares/química , Fosfoproteínas/química , Proteínas de Plantas/química , Proteínas de Plantas/genética , Plantas Tóxicas , Complexo de Endopeptidases do Proteassoma , Proteínas de Ligação a RNA , Ribonucleoproteínas/química , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Serina , Fatores de Processamento de Serina-Arginina , Nicotiana
19.
Plant Cell ; 9(11): 2077-2091, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12237354

RESUMO

Application of the elicitor cryptogein to tobacco (cv Xanthi) is known to evoke external medium alkalinization, active oxygen species production, and phytoalexin synthesis. These are all dependent on an influx of calcium. We show here that cryptogein also induces calcium-dependent plasma membrane depolarization, chloride efflux, cytoplasm acidification, and NADPH oxidation without changes in NAD+ and ATP levels, indicating that the elicitor-activated redox system, responsible for active oxygen species production, uses NADPH in vivo. NADPH oxidation activates the functioning of the pentose phosphate pathway, leading to a decrease in glucose 6-phosphate and to the accumulation of glyceraldehyde 3-phosphate, 3- and 2-phosphoglyceric acid, and phosphoenolpyruvate. By inhibiting the pentose phosphate pathway, we demonstrate that the activation of the plasma membrane NADPH oxidase is responsible for active oxygen species production, external alkalinization, and acidification of the cytoplasm. A model is proposed for the organization of the cryptogein responses measured to date.

20.
Biochim Biophys Acta ; 1285(1): 38-46, 1996 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-8948473

RESUMO

Beticolin-1 and beticolin-2, yellow toxins produced by the phytopathogenic fungus Cercospora beticola, inhibit the plasma membrane H(+)-ATPase. Firstly, since beticolins are able to form complexes with Mg2+, the role of the beticolin/Mg2+ complexes in the inhibition of the plasma membrane proton pump has been investigated. Calculations indicate that beticolins could exist under several forms, in the H(+)-ATPase assay mixture, both free or complexed with Mg2+. However, the percentage inhibition of the H(+)-ATPase activity is correlated to the concentration of one single form of beticolin, the dimeric neutral complex Mg2H2B2, which appears to be the active form involved in the H(+)-ATPase inhibition. Secondly, since previous data suggested that beticolins could also be active against other Mg2(+)-dependent enzymes, we tested beticolin-1 on the vacuolar H(+)-PPase, which requires Mg2+ as co-substrate, and on the alkaline and acid phosphatases, which do not use Mg2+ as co-substrate. Only vacuolar H(+)-PPase is sensitive to beticolin-1, which suggests that beticolins are specific to enzymes that use a complex of Mg2+ as the substrate. The same Mg2H2B2 complex which is responsible of the plasma membrane H(+)-ATPase inhibition appears to be also involved in the inhibition of the vacuolar H(+)-PPase.


Assuntos
Inibidores Enzimáticos/farmacologia , Magnésio/química , Micotoxinas/farmacologia , ATPases Translocadoras de Prótons/antagonistas & inibidores , Pirofosfatases/antagonistas & inibidores , Fosfatase Ácida/antagonistas & inibidores , Fosfatase Alcalina/antagonistas & inibidores , Transporte Biológico Ativo/efeitos dos fármacos , Membrana Celular/enzimologia , Compostos Heterocíclicos de 4 ou mais Anéis , Pirofosfatase Inorgânica , Magnésio/fisiologia , Micotoxinas/química , Vacúolos/enzimologia , Zea mays
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA