Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 423
Filtrar
1.
Nature ; 631(8020): 344-349, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38926575

RESUMO

Many threats to biodiversity cannot be eliminated; for example, invasive pathogens may be ubiquitous. Chytridiomycosis is a fungal disease that has spread worldwide, driving at least 90 amphibian species to extinction, and severely affecting hundreds of others1-4. Once the disease spreads to a new environment, it is likely to become a permanent part of that ecosystem. To enable coexistence with chytridiomycosis in the field, we devised an intervention that exploits host defences and pathogen vulnerabilities. Here we show that sunlight-heated artificial refugia attract endangered frogs and enable body temperatures high enough to clear infections, and that having recovered in this way, frogs are subsequently resistant to chytridiomycosis even under cool conditions that are optimal for fungal growth. Our results provide a simple, inexpensive and widely applicable strategy to buffer frogs against chytridiomycosis in nature. The refugia are immediately useful for the endangered species we tested and will have broader utility for amphibian species with similar ecologies. Furthermore, our concept could be applied to other wildlife diseases in which differences in host and pathogen physiologies can be exploited. The refugia are made from cheap and readily available materials and therefore could be rapidly adopted by wildlife managers and the public. In summary, habitat protection alone cannot protect species that are affected by invasive diseases, but simple manipulations to microhabitat structure could spell the difference between the extinction and the persistence of endangered amphibians.


Assuntos
Anuros , Quitridiomicetos , Resistência à Doença , Espécies em Perigo de Extinção , Micoses , Refúgio de Vida Selvagem , Animais , Anuros/imunologia , Anuros/microbiologia , Anuros/fisiologia , Temperatura Corporal/imunologia , Temperatura Corporal/fisiologia , Temperatura Corporal/efeitos da radiação , Quitridiomicetos/imunologia , Quitridiomicetos/patogenicidade , Quitridiomicetos/fisiologia , Resistência à Doença/imunologia , Resistência à Doença/fisiologia , Resistência à Doença/efeitos da radiação , Ecossistema , Micoses/veterinária , Micoses/microbiologia , Micoses/imunologia , Luz Solar , Animais Selvagens/imunologia , Animais Selvagens/microbiologia , Animais Selvagens/fisiologia , Espécies Introduzidas
2.
Med Sci (Paris) ; 40(4): 343-350, 2024 Apr.
Artigo em Francês | MEDLINE | ID: mdl-38651959

RESUMO

Cancer is an inevitable collateral problem inherent in the evolution of multicellular organisms, which appeared at the end of the Precambrian. Faced to this constraint, a range of diverse anticancer defenses has evolved across the animal kingdom. Today, investigating how animal organisms, especially those of large size and long lifespan, manage cancer-related issues has both fundamental and applied outcomes, as it could inspire strategies for preventing or treating human cancers. In this article, we begin by presenting the conceptual framework for understanding evolutionary theories regarding the development of anti-cancer defenses. We then present a number of examples that have been extensively studied in recent years, including naked mole rats, elephants, whales, placozoa, xenarthras (such as sloths, armadillos and anteaters) and bats. The contributions of comparative genomics to understanding evolutionary convergences are also discussed. Finally, we emphasize that natural selection has also favored anti-cancer adaptations aimed at avoiding mutagenic environments, for example by maximizing immediate reproductive efforts in the event of cancer. Exploring these adaptive solutions holds promise for identifying novel approaches to improve human health.


Title: Évolution de la résistance au cancer dans le monde animal. Abstract: Le cancer est un dommage collatéral inévitable inhérent à l'évolution des organismes multicellulaires, apparus à la fin du Précambrien. L'exploration de la manière dont les animaux, en particulier ceux de grande taille et de longue durée de vie, font face au cancer, comporte des enjeux à la fois fondamentaux et appliqués. Dans cet article, nous commençons par présenter le cadre conceptuel nécessaire pour comprendre les théories qui traitent de l'évolution des défenses anti-cancéreuses. Nous présentons ensuite un certain nombre d'exemples, notamment les rats-taupes nus, les éléphants, les baleines, les xénarthres (paresseux, tatous et fourmiliers), les chauves-souris et les placozoaires1. Les contributions de la génomique comparative à la compréhension des convergences évolutives sont également abordées. Enfin, nous indiquons que la sélection naturelle a également favorisé des adaptations visant à éviter les zones mutagènes, par exemple, ou à maximiser l'effort de reproduction immédiat en cas de cancer. L'exploration de ces solutions, intéressante conceptuellement, pourrait aussi permettre d'envisager de nouvelles approches thérapeutiques pour la santé humaine.


Assuntos
Evolução Biológica , Neoplasias , Animais , Neoplasias/genética , Neoplasias/patologia , Humanos , Resistência à Doença/genética , Resistência à Doença/fisiologia , Seleção Genética , Ratos-Toupeira/fisiologia , Ratos-Toupeira/genética , Elefantes/genética
3.
Phytopathology ; 114(1): 61-72, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37530500

RESUMO

Endophytes play important roles in promoting plant growth and controlling plant diseases. Verticillium wilt is a vascular wilt disease caused by Verticillium dahliae, a widely distributed soilborne pathogen that causes significant economic losses on cotton each year. In this study, an endophyte KRS015, isolated from the seed of the Verticillium wilt-resistant Gossypium hirsutum 'Zhongzhimian No. 2', was identified as Bacillus subtilis by morphological, phylogenetic, physiological, and biochemical analyses. The volatile organic compounds (VOCs) produced by KRS015 or its cell-free fermentation extract had significant antagonistic effects on various pathogenic fungi, including V. dahliae. KRS015 reduced Verticillium wilt index and colonization of V. dahliae in treated cotton seedlings significantly; the disease reduction rate was ∼62%. KRS015 also promoted plant growth, potentially mediated by the growth-related cotton genes GhACL5 and GhCPD-3. The cell-free fermentation extract of KRS015 triggered a hypersensitivity response, including reactive oxygen species (ROS) and expression of resistance-related plant genes. VOCs from KRS015 also inhibited germination of conidia and the mycelial growth of V. dahliae, and were mediated by growth and development-related genes such as VdHapX, VdMcm1, Vdpf, and Vel1. These results suggest that KRS015 is a potential agent for controlling Verticillium wilt and promoting growth of cotton.


Assuntos
Acremonium , Ascomicetos , Verticillium , Bacillus subtilis/genética , Filogenia , Doenças das Plantas/microbiologia , Verticillium/fisiologia , Gossypium/genética , Extratos Vegetais , Resistência à Doença/fisiologia , Regulação da Expressão Gênica de Plantas
4.
Plant Physiol Biochem ; 201: 107814, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37321041

RESUMO

Malate dehydrogenase (MDH) as an essential metabolic enzyme is widely involved in plant developmental processes. However, the direct relationship between its structural basis and in vivo roles especially in plant immunity remains elusive. In this study, we found that cytoplasmic cassava (Manihot esculenta, Me) MDH1 was essential for plant disease resistance against cassava bacterial blight (CBB). Further investigation revealed that MeMDH1 positively modulated cassava disease resistance, accompanying the regulation of salicylic acid (SA) accumulation and pathogensis-related protein 1 (MePR1) expression. Notably, the metabolic product of MeMDH1 (malate) also improved disease resistance in cassava, and its application rescued the disease susceptibility and decreased immune responses of MeMDH1-silenced plants, indicating that malate was responsible for MeMDH1-mediated disease resistance. Interestingly, MeMDH1 relied on Cys330 residues to form homodimer, which was directly related with MeMDH1 enzyme activity and the corresponding malate biosynthesis. The crucial role of Cys330 residue in MeMDH1 was further confirmed by in vivo functional comparison between overexpression of MeMDH1 and MeMDH1C330A in cassava disease resistance. Taken together, this study highlights that MeMDH1 confers improved plant disease resistance through protein self-association to promote malate biosynthesis, extending the knowledge of the relationship between its structure and cassava disease resistance.


Assuntos
Manihot , Manihot/metabolismo , Resistência à Doença/fisiologia , Malato Desidrogenase/genética , Malato Desidrogenase/metabolismo , Malatos/metabolismo , Doenças das Plantas/microbiologia , Verduras
5.
BMC Plant Biol ; 23(1): 294, 2023 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-37264342

RESUMO

BACKGROUND: Plant immunity relies on the perception of immunogenic signals by cell-surface and intracellular receptors and subsequent activation of defense responses like programmed cell death. Under certain circumstances, the fine-tuned innate immune system of plants results in the activation of autoimmune responses that cause constitutive defense responses and spontaneous cell death in the absence of pathogens. RESULTS: Here, we characterized the onset of leaf death 12 (old12) mutant that was identified in the Arabidopsis accession Landsberg erecta. The old12 mutant is characterized by a growth defect, spontaneous cell death, plant-defense gene activation, and early senescence. In addition, the old12 phenotype is temperature reversible, thereby exhibiting all characteristics of an autoimmune mutant. Mapping the mutated locus revealed that the old12 phenotype is caused by a mutation in the Lectin Receptor Kinase P2-TYPE PURINERGIC RECEPTOR 2 (P2K2) gene. Interestingly, the P2K2 allele from Landsberg erecta is conserved among Brassicaceae. P2K2 has been implicated in pathogen tolerance and sensing extracellular ATP. The constitutive activation of defense responses in old12 results in improved resistance against Pseudomonas syringae pv. tomato DC3000. CONCLUSION: We demonstrate that old12 is an auto-immune mutant and that allelic variation of P2K2 contributes to diversity in Arabidopsis immune responses.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Lectinas/genética , Lectinas/metabolismo , Resistência à Doença/fisiologia , Folhas de Planta/metabolismo , Mutação , Proteínas de Transporte/genética , Fenótipo , Receptores Mitogênicos/genética , Receptores Mitogênicos/metabolismo , Pseudomonas syringae/metabolismo , Doenças das Plantas/genética , Regulação da Expressão Gênica de Plantas
6.
Int J Mol Sci ; 23(3)2022 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-35163275

RESUMO

Rice plants contain high basal levels of salicylic acid (SA), but some of their functions remain elusive. To elucidate the importance of SA homeostasis in rice immunity, we characterized four rice SA hydroxylase genes (OsSAHs) and verified their roles in SA metabolism and disease resistance. Recombinant OsSAH proteins catalyzed SA in vitro, while OsSAH3 protein showed only SA 5-hydroxylase (SA5H) activity, which was remarkably higher than that of other OsSAHs that presented both SA3H and SA5H activities. Amino acid substitutions revealed that three amino acids in the binding pocket affected SAH enzyme activity and/or specificity. Knockout OsSAH2 and OsSAH3 (sahKO) genes conferred enhanced resistance to both hemibiotrophic and necrotrophic pathogens, whereas overexpression of each OsSAH gene increased susceptibility to the pathogens. sahKO mutants showed increased SA and jasmonate levels compared to those of the wild type and OsSAH-overexpressing plants. Analysis of the OsSAH3 promoter indicated that its induction was mainly restricted around Magnaporthe oryzae infection sites. Taken together, our findings indicate that SA plays a vital role in immune signaling. Moreover, fine-tuning SA homeostasis through suppression of SA metabolism is an effective approach in studying broad-spectrum disease resistance in rice.


Assuntos
Resistência à Doença/fisiologia , Oryza/genética , Ácido Salicílico/metabolismo , China , Ciclopentanos , Dioxigenases , Expressão Gênica/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Hidroxilação , Oryza/efeitos dos fármacos , Oryza/metabolismo , Oxilipinas , Doenças das Plantas/genética , Imunidade Vegetal/efeitos dos fármacos , Imunidade Vegetal/fisiologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/metabolismo , Ácido Salicílico/farmacologia
7.
Acta Neuropathol Commun ; 10(1): 23, 2022 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-35164877

RESUMO

Clinical symptoms correlate with underlying neurodegenerative changes in the vast majority of people. However, an intriguing group of individuals demonstrate neuropathologic changes consistent with Alzheimer disease (AD) yet remain cognitively normal (termed "resilient"). Previous studies have reported less overall neuronal loss, less gliosis, and fewer comorbidities in these individuals. Herein, NanoString GeoMx™ Digital Spatial Profiler (DSP) technology was utilized to investigate protein expression differences comparing individuals with dementia and AD neuropathologic change to resilient individuals. DSP allows for spatial analysis of protein expression in multiple regions of interest (ROIs) on formalin-fixed paraffin-embedded sections. ROIs in this analysis were hippocampal neurofibrillary tangle (NFT)-bearing neurons, non-NFT-bearing neurons, and their immediate neuronal microenvironments. Analyses of 86 proteins associated with CNS cell-typing or known neurodegenerative changes in 168 ROIs from 14 individuals identified 11 proteins displaying differential expression in NFT-bearing neurons of the resilient when compared to the demented (including APP, IDH1, CD68, GFAP, SYP and Histone H3). In addition, IDH1, CD68, and SYP were differentially expressed in the environment of NFT-bearing neurons when comparing resilient to demented. IDH1 (which is upregulated under energetic and oxidative stress) and PINK1 (which is upregulated in response to mitochondrial dysfunction and oxidative stress) both displayed lower expression in the environment of NFT-bearing neurons in the resilient. Therefore, the resilient display less evidence of energetic and oxidative stress. Synaptophysin (SYP) was increased in the resilient, which likely indicates better maintenance of synapses and synaptic connections. Furthermore, neurofilament light chain (NEFL) and ubiquitin c-terminal hydrolase (Park5) were higher in the resilient in the environment of NFTs. These differences all suggest healthier intact axons, dendrites and synapses in the resilient. In conclusion, resilient individuals display protein expression patterns suggestive of an environment containing less energetic and oxidative stress, which in turn results in maintenance of neurons and their synaptic connections.


Assuntos
Resistência à Doença/fisiologia , Hipocampo/metabolismo , Hipocampo/patologia , Emaranhados Neurofibrilares/metabolismo , Emaranhados Neurofibrilares/patologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neurônios/metabolismo , Neurônios/patologia , Proteômica/métodos , Sinapses/metabolismo , Sinapses/patologia
8.
J Biosci ; 472022.
Artigo em Inglês | MEDLINE | ID: mdl-35092410

RESUMO

Plant hormones regulate growth, development, and defense against biotic and abiotic stresses. Salicylic acid (SA), ethylene (ET), and jasmonate (JA) are major phytohormones that control the defense against pathogens. SA and JA primarily regulate resistance against biotrophic and necrotrophic pathogens, respectively. NPR1 is the key regulator of SA signaling in plants. AtOZF1 function has recently been ascribed to promote both NPR1- dependent and -independent SA signaling. However, the role of AtOZF1 in JA signaling was not known. Here we report AtOZF1 as a positive regulator of JA signaling in Arabidopsis. The atozf1 mutants are more susceptible to the necrotrophic pathogen Botrytis cinerea than wildtype (WT) plants. AtOZF1 positively regulates the expression of JA inducible genes like PDF1.2, VSP2, THI2.1, and ORA59. AtOZF1 takes part in SA-JA cross-talk to an extent similar to that of NPR1. AtOZF1 is essential for the activation of PDF1.2 expression upon exogenous methyl-jasmonate (MeJA) application. Intriguingly, SA can significantly promote MeJA-induced PDF1.2 expression in the absence of AtOZF1. Altogether our results reveal a novel SA-JA interaction pathway in plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Proteínas de Membrana/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Acetatos/metabolismo , Acetatos/farmacologia , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Botrytis/patogenicidade , Ciclopentanos/farmacologia , Defensinas/genética , Defensinas/metabolismo , Resistência à Doença/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana/genética , Mutação , Oxilipinas/farmacologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/metabolismo , Ácido Salicílico/farmacologia , Transdução de Sinais
10.
Plant Physiol ; 188(1): 167-190, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34718797

RESUMO

Fungal infection of grasses, including rice (Oryza sativa), sorghum (Sorghum bicolor), and barley (Hordeum vulgare), induces the formation and accumulation of flavonoid phytoalexins. In maize (Zea mays), however, investigators have emphasized benzoxazinoid and terpenoid phytoalexins, and comparatively little is known about flavonoid induction in response to pathogens. Here, we examined fungus-elicited flavonoid metabolism in maize and identified key biosynthetic enzymes involved in the formation of O-methylflavonoids. The predominant end products were identified as two tautomers of a 2-hydroxynaringenin-derived compound termed xilonenin, which significantly inhibited the growth of two maize pathogens, Fusarium graminearum and Fusarium verticillioides. Among the biosynthetic enzymes identified were two O-methyltransferases (OMTs), flavonoid OMT 2 (FOMT2), and FOMT4, which demonstrated distinct regiospecificity on a broad spectrum of flavonoid classes. In addition, a cytochrome P450 monooxygenase (CYP) in the CYP93G subfamily was found to serve as a flavanone 2-hydroxylase providing the substrate for FOMT2-catalyzed formation of xilonenin. In summary, maize produces a diverse blend of O-methylflavonoids with antifungal activity upon attack by a broad range of fungi.


Assuntos
Antifúngicos/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Resistência à Doença/fisiologia , Flavonoides/metabolismo , Fusarium/patogenicidade , Metiltransferases/metabolismo , Zea mays/metabolismo , Variação Genética , Genótipo , Interações Hospedeiro-Patógeno , Doenças das Plantas/microbiologia , Zea mays/microbiologia
11.
Plant Sci ; 314: 111126, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34895552

RESUMO

Auxin-mediated degradation of Aux/IAA proteins is a crucial step in auxin signaling. Recent researches indicate that Aux/IAA members also play a role in biotic and abiotic stresses. For example, Pseudomonas syringae infection causes Arabidopsis Aux/IAA protein (AXR2, AXR3) turnover. Here, by analyzing RNA-seq data we found that several cotton Aux/IAA genes are responsive to Verticillium dahliae infection, one of these named GhIAA43, was investigated for its role in cotton defense against V. dahliae infection. We demonstrate that the transcript levels of GhIAA43 were responsive to both V. dahliae infection and exogenous IAA application. By producing transgenic Arabidopsis plants overexpressing GhIAA43-GUS fusion, we show that IAA treatment and V. dahliae infection promoted GhIAA43 protein turnover. Silencing GhIAA43 in cotton enhanced wilt resistance, suggesting that GhIAA43 is a negative regulator in cotton defense against V. dahliae attack. By monitoring SA marker gene expression and measurement of SA content in GhIAA43-silenced cotton plants, we found that the enhanced resistance in GhIAA43-silenced cotton plants is due to the activation of SA-related defenses, and the activated defenses specifically occurred in the presence of V. dahliae. Furthermore, exogenous IAA application improve wilt resistance in cotton plants tested. Our results provide novel connection between auxin signaling and SA-related defenses in cotton upon V. dahliae attack.


Assuntos
Ascomicetos/patogenicidade , Resistência à Doença/genética , Gossypium/genética , Gossypium/microbiologia , Interações Hospedeiro-Patógeno/genética , Ácidos Indolacéticos/metabolismo , Ácido Salicílico/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/microbiologia , Resistência à Doença/fisiologia , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Genes de Plantas , Variação Genética , Genótipo , Interações Hospedeiro-Patógeno/fisiologia , Doenças das Plantas
12.
FEMS Microbiol Lett ; 368(20)2021 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-34751779

RESUMO

Gray mold caused by Botrytis cinerea is a major cause of economic losses during tomato production. In this study, we obtained 23 Trichoderma strains from tomato rhizosphere soil and their inhibitory effects on B. cinerea and the promoting effects on tomato growth were determined. Among them, the inhibition rate of strain DQ-1 on B. cinerea was 88.56%; compared with the control group, after treatment with strain DQ-1, the seeds germination rate and root length of tomato increased by 5.55 and 37.86%. The induced disease resistance of strain DQ-1 was evaluated by pot experiments. The disease incidence (DI) and disease severity index (DSI) of tomato pre-inoculated with strain DQ-1 and then inoculated with B. cinerea were reduced by 38 and 64% compared with the control. Furthermore, we detected the expression levels of tomato disease resistance related genes PR2 and TPX, ethylene pathway related genes ETR1 and CTR1 and jasmonic acid pathway related genes LOX1 and PAL in challenging and non-challenging inoculation treatments. The results showed that the tomato treated with strain DQ-1 triggered the system acquired resistance (SAR) and induced systemic resistance (ISR) pathway, thereby enhancing the disease resistance of tomato. Then the strain DQ-1 was identified as Trichoderma asperellum based on morphological characteristics and phylogenetic information. This study suggests that the novel T. asperellum strain DQ-1 can be a potential candidate for the biological control of gray mold in tomato.


Assuntos
Botrytis , Resistência à Doença , Hypocreales , Interações Microbianas , Doenças das Plantas , Solanum lycopersicum , Botrytis/fisiologia , Resistência à Doença/fisiologia , Hypocreales/classificação , Hypocreales/fisiologia , Solanum lycopersicum/microbiologia , Interações Microbianas/fisiologia , Filogenia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle
13.
Molecules ; 26(22)2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34833910

RESUMO

The greatest challenge for the avocado (Persea americana Miller) industry is to maintain the quality of the fruit to meet consumer requirements. Anthracnose is considered the most important disease in this industry, and it is caused by different species of the genus Colletotrichum, although other pathogens can be equally important. The defense mechanisms that fruit naturally uses can be triggered in response to the attack of pathogenic microorganisms and also by the application of exogenous elicitors in the form of GRAS compounds. The elicitors are recognized by receptors called PRRs, which are proteins located on the avocado fruit cell surface that have high affinity and specificity for PAMPs, MAMPs, and DAMPs. The activation of defense-signaling pathways depends on ethylene, salicylic, and jasmonic acids, and it occurs hours or days after PTI activation. These defense mechanisms aim to drive the pathogen to death. The application of essential oils, antagonists, volatile compounds, chitosan and silicon has been documented in vitro and on avocado fruit, showing some of them to have elicitor and fungicidal effects that are reflected in the postharvest quality of the fruit and a lower incidence of diseases. The main focus of these studies has been on anthracnose diseases. This review presents the most relevant advances in the use of natural compounds with antifungal and elicitor effects in plant tissues.


Assuntos
Colletotrichum/patogenicidade , Persea/microbiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Antifúngicos/farmacologia , Agentes de Controle Biológico/farmacologia , Quitosana/farmacologia , Colletotrichum/efeitos dos fármacos , Resistência à Doença/fisiologia , Frutas/efeitos dos fármacos , Frutas/microbiologia , Frutas/fisiologia , Óleos Voláteis/farmacologia , Persea/efeitos dos fármacos , Persea/fisiologia , Compostos Orgânicos Voláteis/farmacologia
14.
PLoS Pathog ; 17(10): e1010015, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34665847

RESUMO

Clostridioides difficile infections occur upon ecological / metabolic disruptions to the normal colonic microbiota, commonly due to broad-spectrum antibiotic use. Metabolism of bile acids through a 7α-dehydroxylation pathway found in select members of the healthy microbiota is regarded to be the protective mechanism by which C. difficile is excluded. These 7α-dehydroxylated secondary bile acids are highly toxic to C. difficile vegetative growth, and antibiotic treatment abolishes the bacteria that perform this metabolism. However, the data that supports the hypothesis that secondary bile acids protect against C. difficile infection is supported only by in vitro data and correlative studies. Here we show that bacteria that 7α-dehydroxylate primary bile acids protect against C. difficile infection in a bile acid-independent manner. We monoassociated germ-free, wildtype or Cyp8b1-/- (cholic acid-deficient) mutant mice and infected them with C. difficile spores. We show that 7α-dehydroxylation (i.e., secondary bile acid generation) is dispensable for protection against C. difficile infection and provide evidence that Stickland metabolism by these organisms consumes nutrients essential for C. difficile growth. Our findings indicate secondary bile acid production by the microbiome is a useful biomarker for a C. difficile-resistant environment but the microbiome protects against C. difficile infection in bile acid-independent mechanisms.


Assuntos
Ácidos e Sais Biliares/metabolismo , Infecções por Clostridium/metabolismo , Resistência à Doença/fisiologia , Microbioma Gastrointestinal/fisiologia , Animais , Camundongos , Camundongos Knockout
15.
Bull Exp Biol Med ; 171(4): 461-463, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34542751

RESUMO

The level of viremia and features of the course of experimental infection caused by West Nile virus were studied in two species of migratory birds, siskins Сarduelis spinus and quails Coturnix coturnix, and in one species of amphibians, frogs Rana ridibunda. In quails, the virus caused a fatal disease; histological analysis revealed pathological changes in the heart, kidneys, liver, and brain stem. In siskins and frogs, virus antigen was detected in cloacal smears despite the absence of clinical manifestations, the level of viremia was sufficient to infect insect vectors during bloodsucking. These findings suggest that siskins and frogs can be potential reservoirs of West Nile virus and play a role in its circulation.


Assuntos
Coturnix/virologia , Tentilhões/virologia , Rana ridibunda/virologia , Vírus do Nilo Ocidental/patogenicidade , Animais , Chlorocebus aethiops , Coturnix/fisiologia , Modelos Animais de Doenças , Resistência à Doença/fisiologia , Tentilhões/fisiologia , Interações Hospedeiro-Patógeno/fisiologia , Camundongos , Rana ridibunda/fisiologia , Células Vero , Viremia/sangue , Viremia/imunologia , Viremia/veterinária , Febre do Nilo Ocidental/mortalidade , Febre do Nilo Ocidental/patologia , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/fisiologia
16.
BMC Plant Biol ; 21(1): 382, 2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34412592

RESUMO

BACKGROUND: Cysteine-rich receptor-like kinases (CRKs) represent a large subfamily of receptor-like kinases and play vital roles in diverse physiological processes in regulating plant growth and development. RESULTS: CaCRK5 transcripts were induced in pepper upon the infection of Ralstonia solanacearum and treatment with salicylic acid. The fusions between CaCRK5 and green fluorescence protein were targeted to the plasma membrane. Suppression of CaCRK5 via virus-induced gene silencing (VIGS) made pepper plants significantly susceptible to R. solanacearum infection, which was accompanied with decreased expression of defense related genes CaPR1, CaSAR8.2, CaDEF1 and CaACO1. Overexpression of CaCRK5 increased resistance against R. solanacearum in Nicotiana benthamiana. Furthermore, electrophoretic mobility shift assay and chromatin immunoprecipitation coupled with quantitative real-time PCR analysis revealed that a homeodomain zipper I protein CaHDZ27 can active the expression of CaCRK5 through directly binding to its promoter. Yeast two-hybrid and bimolecular fluorescence complementation (BiFC) analyses suggested that CaCRK5 heterodimerized with the homologous member CaCRK6 on the plasma membrane. CONCLUSIONS: Our data revealed that CaCRK5 played a positive role in regulating immune responses against R. solanacearum infection in pepper.


Assuntos
Capsicum/genética , Capsicum/microbiologia , Cisteína/genética , Cisteína/metabolismo , Resistência à Doença/genética , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Ralstonia solanacearum/patogenicidade , Capsicum/fisiologia , China , Resistência à Doença/fisiologia , Regulação da Expressão Gênica de Plantas
17.
Microbiologyopen ; 10(4): e1226, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34459555

RESUMO

Defense compounds generally inhibit microbial colonization of plants. In this study, we examined the presence of endophytes in Passiflora edulis seeds that accumulate resveratrol and piceatannol at extremely high levels as defense compounds. Interestingly, although no microbial colonies appeared on an agar growth medium from the cut or homogenized seeds, colonies were generated from cut seedlings derived from the seeds. A total of 19 bacterial strains were isolated, of which 15 were classified as Gram-positive. As we hypothesized that extremely high levels of piceatannol in the seeds would inhibit the growth of endophytes cultured directly from the seeds, we examined the antimicrobial activity of this compound against the isolated bacteria. Piceatannol exerted bacteriostatic rather than bactericidal effects on most of the bacteria tested. These results suggest that the bacteria remain static in the seeds due to the presence of piceatannol and are transmitted to the seedlings during the germination process, enabling colonies to be established from the seedlings on the agar medium. We also investigated the biocatalytic activity of the isolated bacteria toward resveratrol and piceatannol. One bacterium, Brevibacterium sp. PE28-2, converted resveratrol and piceatannol to their respective derivatives. This strain is the first endophyte shown to exhibit such activity.


Assuntos
Bactérias/crescimento & desenvolvimento , Passiflora/microbiologia , Resveratrol/metabolismo , Sementes/microbiologia , Estilbenos/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Resistência à Doença/fisiologia , Endófitos/isolamento & purificação , Testes de Sensibilidade Microbiana , Resveratrol/farmacologia , Sementes/metabolismo , Estilbenos/farmacologia
18.
PLoS One ; 16(7): e0254808, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34293017

RESUMO

MicroRNA-like small RNAs (milRNAs) and their regulatory roles in the interaction between plant and fungus have recently aroused keen interest of plant pathologists. Trichoderma spp., one of the widespread biocontrol fungi, can promote plant growth and induce plant disease resistance. To investigate milRNAs potentially involved in the interaction between Trichoderma and tomato roots, a small RNA (sRNA) library expressed during the interaction of T. asperellum DQ-1 and tomato roots was constructed and sequenced using the Illumina HiSeqTM 2500 sequencing platform. From 13,464,142 sRNA reads, we identified 21 milRNA candidates that were similar to other known microRNAs in the miRBase database and 22 novel milRNA candidates that possessed a stable microRNA precursor hairpin structure. Among them, three milRNA candidates showed different expression level in the interaction according to the result of stem-loop RT-PCR indicating that these milRNAs may play a distinct regulatory role in the interaction between Trichoderma and tomato roots. The potential transboundary milRNAs from T. asperellum and their target genes in tomato were predicted by bioinformatics analysis. The results revealed that several interesting proteins involved in plant growth and development, disease resistance, seed maturation, and osmotic stress signal transduction might be regulated by the transboundary milRNAs. To our knowledge, this is the first report of milRNAs taking part in the process of interaction of T. asperellum and tomato roots and associated with plant promotion and disease resistance. The results might be useful to unravel the mechanism of interaction between Trichoderma and tomato.


Assuntos
Interações Hospedeiro-Patógeno/fisiologia , Hypocreales/fisiologia , MicroRNAs/biossíntese , Raízes de Plantas/microbiologia , RNA Fúngico/biossíntese , Solanum lycopersicum/microbiologia , Resistência à Doença/fisiologia , MicroRNAs/genética , RNA Fúngico/genética
19.
J Plant Physiol ; 263: 153466, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34216845

RESUMO

Panax notoginseng (Bruk.) FH Chen is a valuable traditional herb in China, with saponins being the main medicinal components in its roots. However, leaf diseases are a major factor limiting growth and production of P. notoginseng. Melatonin is a ubiquitous signaling molecule associated with abiotic stress resistance. In this study, we investigated the role of melatonin in leaf disease resistance of P. notoginseng in field conditions. Additionally, saponin concentrations were analyzed to evaluate the suitability of melatonin use in agricultural practice. Our results showed that exogenous application of melatonin promoted the endogenous phytomelatonin accumulation via upregulation of genes involved in its biosynthesis. The application of 10 µM melatonin decreased the incidence of leaf diseases (gray mold, round spot, and black spot) by about 40% compared with the solvent control, which might have been due to the increased expression of genes associated with immunity and disease resistance. Furthermore, concentrations of saponins and expression of their biosynthesis-related genes were significantly increased by melatonin. Taken together, the data presented here suggested that melatonin could be used in agricultural management of P. notoginseng because it increased leaf disease resistance and biosynthesis of saponins.


Assuntos
Resistência à Doença/fisiologia , Melatonina/metabolismo , Panax notoginseng/crescimento & desenvolvimento , Panax notoginseng/metabolismo , Doenças das Plantas , Folhas de Planta/metabolismo , Saponinas/biossíntese , China , Plantas Medicinais/crescimento & desenvolvimento , Plantas Medicinais/metabolismo
20.
J Exp Med ; 218(9)2021 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-34313734

RESUMO

Bats are attracting the greatest attention recently as a putative reservoir of SARS-CoV-2 responsible for the COVID-19 pandemic. However, less known to the public, bats also have several unique traits of high value to human health. The lessons we learn from bats can potentially help us fight many human diseases, including infection, aging, and cancer.


Assuntos
Quirópteros/fisiologia , Quirópteros/virologia , Resistência à Doença/fisiologia , Animais , Animais de Laboratório , COVID-19 , Modelos Animais de Doenças , Humanos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...