Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
1.
Genome Res ; 26(6): 812-25, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27197216

RESUMO

Although the concept of botanical carnivory has been known since Darwin's time, the molecular mechanisms that allow animal feeding remain unknown, primarily due to a complete lack of genomic information. Here, we show that the transcriptomic landscape of the Dionaea trap is dramatically shifted toward signal transduction and nutrient transport upon insect feeding, with touch hormone signaling and protein secretion prevailing. At the same time, a massive induction of general defense responses is accompanied by the repression of cell death-related genes/processes. We hypothesize that the carnivory syndrome of Dionaea evolved by exaptation of ancient defense pathways, replacing cell death with nutrient acquisition.


Assuntos
Droseraceae/genética , Droseraceae/citologia , Droseraceae/metabolismo , Genoma de Planta , Herbivoria , Folhas de Planta/citologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais , Transcriptoma
2.
J Transl Med ; 17(1): 233, 2019 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-31331335

RESUMO

BACKGROUND: The use of one-step nucleic acid amplification (OSNA) allows for lymph node (LN) metastasis to be detected rapidly and accurately. We conducted a prospective single-centre clinical trial to evaluate OSNA assay in detecting LN metastasis of lung cancer. PATIENTS AND METHODS: A total of 705 LNs from 160 patients with clinical stage IA to IVA lung cancer were included in this study. The LNs were divided and submitted to routine histological diagnosis and OSNA assay and the results were compared. We also examined keratin 19 expression of different histological types lung primary tumours. RESULTS: When the cut-off value was set to 250 copies/µl, the concordance rate between the two methods was 96.17% and the sensitivity 97.14%. Discordant results were observed in 27 LNs of 21 patients. Most of these discordant results were molecular micrometastasis expressing a very low number of copies with negative histology. Most thoracic tumours were positive for keratin 19. CONCLUSIONS: Our data show that the OSNA assay might be a useful and sensitive method to diagnose LN metastasis in lung cancer and could be applied to intraoperative decision-making in personalised lung cancer surgery based on LN status and a more accurate staging of patients.


Assuntos
Neoplasias Pulmonares/patologia , Metástase Linfática/diagnóstico , Técnicas de Amplificação de Ácido Nucleico/métodos , Adulto , Idoso , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Queratina-19/genética , Queratina-19/metabolismo , Neoplasias Pulmonares/genética , Linfonodos/patologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
3.
New Phytol ; 210(3): 922-33, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26831448

RESUMO

Extrafloral nectaries secrete a sweet sugar cocktail that lures predator insects for protection from foraging herbivores. Apart from sugars and amino acids, the nectar contains the anions chloride and nitrate. Recent studies with Populus have identified a type of nectary covered by apical bipolar epidermal cells, reminiscent of the secretory brush border epithelium in animals. Border epithelia operate transepithelial anion transport, which is required for membrane potential and/or osmotic adjustment of the secretory cells. In search of anion transporters expressed in extrafloral nectaries, we identified PttSLAH3 (Populus tremula × Populus tremuloides SLAC1 Homologue3), an anion channel of the SLAC/SLAH family. When expressed in Xenopus oocytes, PttSLAH3 displayed the features of a voltage-dependent anion channel, permeable to both nitrate and chloride. In contrast to the Arabidopsis SLAC/SLAH family members, the poplar isoform PttSLAH3 is independent of phosphorylation activation by protein kinases. To understand the basis for the autonomous activity of the poplar SLAH3, we generated and expressed chimera between kinase-independent PttSLAH3 and kinase-dependent Arabidopsis AtSLAH3. We identified the N-terminal tail and, to a lesser extent, the C-terminal tail as responsible for PttSLAH3 kinase-(in)dependent action. This feature of PttSLAH3 may provide the secretory cell with a channel probably controlling long-term nectar secretion.


Assuntos
Ânions/metabolismo , Epitélio/metabolismo , Canais Iônicos/metabolismo , Proteínas de Plantas/metabolismo , Populus/metabolismo , Proteínas Quinases/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Epitélio/efeitos dos fármacos , Flores/efeitos dos fármacos , Flores/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Nitratos/farmacologia , Néctar de Plantas , Proteínas de Plantas/química , Populus/efeitos dos fármacos , Proteínas Recombinantes de Fusão/metabolismo , Relação Estrutura-Atividade
4.
Biochim Biophys Acta ; 1844(2): 374-83, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24275507

RESUMO

Predation plays a major role in energy and nutrient flow in the biological food chain. Plant carnivory has attracted much interest since Darwin's time, but many fundamental properties of the carnivorous lifestyle are largely unexplored. In particular, the chain of events leading from prey perception to its digestive utilization remains to be elucidated. One of the first steps after the capture of animal prey, i.e. the enzymatic breakup of the insects' chitin-based shell, is reflected by considerable chitinase activity in the secreted digestive fluid in the carnivorous plant Venus flytrap. This study addresses the molecular nature, function, and regulation of the underlying enzyme, VF chitinase-I. Using mass spectrometry based de novo sequencing, VF chitinase-I was identified in the secreted fluid. As anticipated for one of the most prominent proteins in the flytrap's "green stomach" during prey digestion, transcription of VF chitinase-I is restricted to glands and enhanced by secretion-inducing stimuli. In their natural habitat, Venus flytrap is exposed to high temperatures. We expressed and purified recombinant VF chitinase-I and show that the enzyme exhibits the hallmark properties expected from an enzyme active in the hot and acidic digestive fluid of Dionaea muscipula. Structural modeling revealed a relative compact globular form of VF chitinase-I, which might contribute to its overall stability and resistance to proteolysis. These peculiar characteristics could well serve industrial purposes, especially because of the ability to hydrolyze both soluble and crystalline chitin substrates including the commercially important cleavage of α-chitin.


Assuntos
Artrópodes/fisiologia , Quitinases/metabolismo , Digestão , Droseraceae/enzimologia , Cadeia Alimentar , Sequência de Aminoácidos , Animais , Quitina/metabolismo , Quitinases/química , Quitinases/genética , Clonagem Molecular , Droseraceae/genética , Modelos Moleculares , Dados de Sequência Molecular , Pichia , Estrutura Secundária de Proteína
5.
Plant J ; 73(4): 546-54, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23075038

RESUMO

Despite the ecological and evolutionary importance of nectar, mechanisms controlling its synthesis and secretion remain largely unknown. It is widely believed that nectar is 'secreted phloem sap', but current research reveals a biochemical complexity that is unlikely to stem directly from the phloem. We used the short daily peak in production of extrafloral nectar by Acacia cornigera to investigate metabolic and proteomic dynamics before, during and after 2 h of diurnal secretion. Neither hexoses nor dominating nectar proteins (nectarins) were detected in the phloem before or during nectar secretion, excluding the phloem as the direct source of major nectar components. Enzymes involved in the anabolism of sugars, amino acids, proteins, and nectarins, such as invertase, ß-1,3-glucanase and thaumatin-like protein, accumulated in the nectary directly before secretion and diminished quantitatively after the daily secretion process. The corresponding genes were expressed almost exclusively in nectaries. By contrast, protein catabolic enzymes were mainly present and active after the secretion peak, and may function in termination of the secretion process. Thus the metabolic machinery for extrafloral nectar production is synthesized and active during secretion and degraded thereafter. Knowing the key enzymes involved and the spatio-temporal patterns in their expression will allow elucidation of mechanisms by which plants control nectar quality and quantity.


Assuntos
Acacia/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Néctar de Plantas/metabolismo , Acacia/enzimologia , Glucana 1,3-beta-Glucosidase/genética , Glucana 1,3-beta-Glucosidase/metabolismo , Especificidade de Órgãos , Floema/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteólise , Proteoma/análise , Proteômica , Especificidade da Espécie , Fatores de Tempo , beta-Frutofuranosidase/genética , beta-Frutofuranosidase/metabolismo
6.
Mol Cell Proteomics ; 11(11): 1306-19, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22891002

RESUMO

The Venus flytrap (Dionaea muscipula) is one of the most well-known carnivorous plants because of its unique ability to capture small animals, usually insects or spiders, through a unique snap-trapping mechanism. The animals are subsequently killed and digested so that the plants can assimilate nutrients, as they grow in mineral-deficient soils. We deep sequenced the cDNA from Dionaea traps to obtain transcript libraries, which were used in the mass spectrometry-based identification of the proteins secreted during digestion. The identified proteins consisted of peroxidases, nucleases, phosphatases, phospholipases, a glucanase, chitinases, and proteolytic enzymes, including four cysteine proteases, two aspartic proteases, and a serine carboxypeptidase. The majority of the most abundant proteins were categorized as pathogenesis-related proteins, suggesting that the plant's digestive system evolved from defense-related processes. This in-depth characterization of a highly specialized secreted fluid from a carnivorous plant provides new information about the plant's prey digestion mechanism and the evolutionary processes driving its defense pathways and nutrient acquisition.


Assuntos
Droseraceae/metabolismo , Insetos/metabolismo , Exsudatos de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Sequência de Aminoácidos , Animais , DNA Complementar/genética , Droseraceae/enzimologia , Droseraceae/genética , Sequenciamento de Nucleotídeos em Larga Escala , Dados de Sequência Molecular , Folhas de Planta/metabolismo , Proteínas de Plantas/química , Proteólise , Alinhamento de Sequência , Transcriptoma
7.
Proc Natl Acad Sci U S A ; 108(37): 15492-7, 2011 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-21896747

RESUMO

Venus flytrap's leaves can catch an insect in a fraction of a second. Since the time of Charles Darwin, scientists have struggled to understand the sensory biology and biomechanics of this plant, Dionaea muscipula. Here we show that insect-capture of Dionaea traps is modulated by the phytohormone abscisic acid (ABA) and jasmonates. Water-stressed Dionaea, as well as those exposed to the drought-stress hormone ABA, are less sensitive to mechanical stimulation. In contrast, application of 12-oxo-phytodienoic acid (OPDA), a precursor of the phytohormone jasmonic acid (JA), the methyl ester of JA (Me-JA), and coronatine (COR), the molecular mimic of the isoleucine conjugate of JA (JA-Ile), triggers secretion of digestive enzymes without any preceding mechanical stimulus. Such secretion is accompanied by slow trap closure. Under physiological conditions, insect-capture is associated with Ca(2+) signaling and a rise in OPDA, Apparently, jasmonates bypass hapto-electric processes associated with trap closure. However, ABA does not affect OPDA-dependent gland activity. Therefore, signals for trap movement and secretion seem to involve separate pathways. Jasmonates are systemically active because application to a single trap induces secretion and slow closure not only in the given trap but also in all others. Furthermore, formerly touch-insensitive trap sectors are converted into mechanosensitive ones. These findings demonstrate that prey-catching Dionaea combines plant-specific signaling pathways, involving OPDA and ABA with a rapidly acting trigger, which uses ion channels, action potentials, and Ca(2+) signals.


Assuntos
Droseraceae/anatomia & histologia , Droseraceae/fisiologia , Reguladores de Crescimento de Plantas/farmacologia , Ácido Abscísico/farmacologia , Potenciais de Ação/efeitos dos fármacos , Aminoácidos/farmacologia , Animais , Ciclopentanos/farmacologia , Droseraceae/efeitos dos fármacos , Ácidos Graxos Insaturados/biossíntese , Indenos/farmacologia , Insetos/efeitos dos fármacos , Insetos/fisiologia , Oxilipinas/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Comportamento Predatório/efeitos dos fármacos , Estresse Mecânico , Fatores de Tempo
8.
Plant Physiol ; 159(3): 1176-91, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22573802

RESUMO

Many plant species grow extrafloral nectaries and produce nectar to attract carnivore arthropods as defenders against herbivores. Two nectary types that evolved with Populus trichocarpa (Ptr) and Populus tremula × Populus tremuloides (Ptt) were studied from their ecology down to the genes and molecules. Both nectary types strongly differ in morphology, nectar composition and mode of secretion, and defense strategy. In Ptt, nectaries represent constitutive organs with continuous merocrine nectar flow, nectary appearance, nectar production, and flow. In contrast, Ptr nectaries were found to be holocrine and inducible. Neither mechanical wounding nor the application of jasmonic acid, but infestation by sucking insects, induced Ptr nectar secretion. Thus, nectaries of Ptr and Ptt seem to answer the same threat by the use of different mechanisms.


Assuntos
Flores/imunologia , Flores/parasitologia , Herbivoria/fisiologia , Néctar de Plantas/imunologia , Néctar de Plantas/fisiologia , Populus/fisiologia , Populus/parasitologia , Aminoácidos/metabolismo , Animais , Análise por Conglomerados , Exocitose/genética , Ácidos Graxos Voláteis/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Insetos/fisiologia , Larva/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , Especificidade de Órgãos/genética , Folhas de Planta/parasitologia , Folhas de Planta/ultraestrutura , Néctar de Plantas/metabolismo , Populus/genética , Populus/imunologia , Estresse Fisiológico
9.
Curr Biol ; 23(17): 1649-57, 2013 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-23954430

RESUMO

BACKGROUND: Ammonium transporter (AMT/MEP/Rh) superfamily members mediate ammonium uptake and retrieval. This pivotal transport system is conserved among all living organisms. For plants, nitrogen represents a macronutrient available in the soil as ammonium, nitrate, and organic nitrogen compounds. Plants living on extremely nutrient-poor soils have developed a number of adaptation mechanisms, including a carnivorous lifestyle. This study addresses the molecular nature, function, and regulation of prey-derived ammonium uptake in the Venus flytrap, Dionaea muscipula, one of the fastest active carnivores. RESULTS: The Dionaea muscipula ammonium transporter DmAMT1 was localized in gland complexes where its expression was upregulated upon secretion. These clusters of cells decorating the inner trap surface are engaged in (1) secretion of an acidic digestive enzyme cocktail and (2) uptake of prey-derived nutrients. Voltage clamp of Xenopus oocytes expressing DmAMT1 and membrane potential recordings with DmAMT1-expressing Dionaea glands were used to monitor and compare electrophysiological properties of DmAMT1 in vitro and in planta. DmAMT1 exhibited the hallmark biophysical properties of a NH4(+)-selective channel. At depolarized membrane potentials (Vm = 0), the Km (3.2 ± 0.3 mM) indicated a low affinity of DmAMT1 for ammonium that increased systematically with negative going voltages. Upon hyperpolarization to, e.g., -200 mV, a Km of 0.14 ± 0.015 mM documents the voltage-dependent shift of DmAMT1 into a NH4(+) transport system of high affinity. CONCLUSIONS: We suggest that regulation of glandular DmAMT1 and membrane potential readjustments of the endocrine cells provide for effective adaptation to varying, prey-derived ammonium sources.


Assuntos
Compostos de Amônio/metabolismo , Droseraceae/metabolismo , Canais Iônicos/metabolismo , Animais , Droseraceae/fisiologia , Dados de Sequência Molecular , Xenopus laevis
11.
Planta ; 229(2): 299-309, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18946679

RESUMO

In this study the impact of salt stress on the physiology and wood structure of the salt-sensitive Populus x canescens was investigated. Two weeks of salt stress altered wood anatomy significantly. The xylem differentiation zone was reduced and the resulting vessels exhibited reduced lumina. To understand this phenomenon, ion composition, levels of corresponding transcripts and of the stress hormone ABA were analysed. With increasing sodium and chloride concentrations, a general reduction of potassium was found in roots and shoots, but not in leaves. Consequently, the corresponding K+ channel transcripts in roots favoured K+ release. The overall osmolarity in leaves was up to fourfold higher than in roots or shoots. Therefore, adjustment of the K+/Na+ balance seemed not to be required in leaves. Sodium increased gradually from roots to shoots and then to leaves indicating that sodium storage took place first in roots, then in shoots, and finally in leaves to protect photosynthesis from salt effects as long as possible. Since leaf abscisic acid levels markedly increased, stomatal closure seemed to limit CO2 uptake. As a consequence, diminished nutrient supply to the cambium in combination with lowered shoot K+ content led to decreased vessel lumina, and a reduction of the radial cambium was observed. Thus, xylem differentiation was curtailed and the development of full size vessels was impaired.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Cruzamentos Genéticos , Populus/citologia , Populus/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Xilema/citologia , Ácido Abscísico/metabolismo , Arabidopsis/genética , Transporte Biológico/efeitos dos fármacos , Elementos Químicos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Malatos/metabolismo , Filogenia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Populus/genética , Potássio/metabolismo , Canais de Potássio/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sódio/metabolismo , Madeira/citologia , Madeira/efeitos dos fármacos , Xilema/efeitos dos fármacos , Xilema/ultraestrutura
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa