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1.
Int J Adv Couns ; : 1-18, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-37359035

RESUMO

For Chinese international students attending colleges and universities, COVID-19 and protests related to racism intertwined to create impactful experiences. In this narrative inquiry study, Emma's experiences as a graduate student culminate in her story of identity and racism. Narrative themes of personal and cultural identity, experience and interactions with racism, privilege, and advocacy and social responsibility were constructed.

2.
Methods Mol Biol ; 2406: 169-187, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35089557

RESUMO

Development of recombinant enzymes as industrial biocatalysts or metabolic pathway elements requires soluble expression of active protein. Here we present a two-step strategy, combining a directed evolution selection with an enzyme activity screen, to increase the soluble production of enzymes in the cytoplasm of E. coli. The directed evolution component relies on the innate quality control of the twin-arginine translocation pathway coupled with antibiotic selection to isolate point mutations that promote intracellular solubility. A secondary screen is applied to ensure the solubility enhancement has not compromised enzyme activity. This strategy has been successfully applied to increase the soluble production of a fungal endocellulase by 30-fold in E. coli without change in enzyme specific activity through two rounds of directed evolution.


Assuntos
Escherichia coli , Escherichia coli/metabolismo , Solubilidade
3.
J Med Libr Assoc ; 110(4): 399-408, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37114237

RESUMO

The Hospital Library Caucus of the Medical Library Association (MLA) follows the practice established in 1953 of developing quality indicators and best practices in the newly developing and fast-changing world of hospital libraries. As these libraries increased in number and prominence, the Joint Commission on the Accreditation of Hospitals (JCAHO) included in 1978 a hospital library standard developed in collaboration with MLA. Subsequent changes in JCAHO, then The Joint Commission (TJC) knowledge management criteria as well as technological changes in the curation and delivery of evidence-based resources influenced standards changes over the years. The 2022 standards mark the most recent edition, replacing the 2007 standards.


Assuntos
Bibliotecários , Bibliotecas Hospitalares , Bibliotecas Médicas , Humanos , Hospitais , Joint Commission on Accreditation of Healthcare Organizations , Bibliotecas Hospitalares/normas , Associações de Bibliotecas , Estados Unidos
4.
Int J Adv Couns ; 43(4): 534-552, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34334848

RESUMO

The purpose of this study was to explore Chinese international college students' lived experiences during the initial COVID-19 quarantine period in the United States. Using a descriptive phenomenological psychological method, data were gathered from 14 international students and visiting scholars from China using individual and focus group interviews. Four transformed meaning units that formed the structural base of the phenomenal experience were identified as Safety Concerns, The Salience of the English Language, Intersectionality of Policies and Complex Decision Making, and Unexpected Support and Benefits. Implications for policy making and support for international students' learning in the U.S. higher education institutions and future research recommendations are included.

5.
Med Ref Serv Q ; 39(2): 153-164, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32329678

RESUMO

In 2017, Document Delivery Services (DDS) at Memorial Sloan Kettering Cancer Center Medical Library launched a customer satisfaction survey. The last time a survey of this nature was implemented was in 2009, before switching to ILLiad for the management of resource sharing requests. Due to the changing nature of content accessibility and online research methods, the DDS team felt that the time was right to survey their users again to seek feedback in support of service improvements. Questions were created to evaluate users' satisfaction and knowledge of the service and related resources. New survey results were compared where possible to those received in 2009 to determine if survey results had changed over time. Enhancements were made to the service based on responses received in the 2017 survey.


Assuntos
Comportamento do Consumidor , Bibliotecas Médicas/normas , Melhoria de Qualidade , Hospitais , Humanos , Cidade de Nova Iorque , Estudos de Casos Organizacionais , Inquéritos e Questionários
6.
Med Ref Serv Q ; 38(1): 87-96, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30942680

RESUMO

The primary goal of this project is to understand how each National Cancer Institute-designated cancer center library, and all libraries that support cancer research, function within their institutions. Through an in-depth survey focused on three major areas (staff, content and tools procurement, and user services), the research team hopes to determine how a cancer-centric library can be successful in supporting quality patient care, research excellence, and education. Additionally, the survey will examine the necessary minimum staffing levels for librarians and information professionals based on organizational size and degree of research focus. The survey will seek out the new skills librarians will need to deliver optimal services. The survey will also explore how content libraries purchase reflects and maps to constituents' current medical and research activities. Libraries within a research intense environment have a responsibility to align with researchers and health care professionals to provide resources and services that support their workflows. Cancer libraries need to be attuned to their institutions' missions, whether that includes excellent patient care, research endeavors, or cutting-edge educational programs. The information gathered from the survey will provide data for this research team to define the vision and standards of excellence for a cancer specialized research library.


Assuntos
Bases de Dados Bibliográficas/normas , Armazenamento e Recuperação da Informação/normas , Bibliotecas Médicas/normas , Desenvolvimento de Coleções em Bibliotecas/normas , Levantamentos de Bibliotecas/normas , Neoplasias , Bases de Dados Bibliográficas/tendências , Previsões , Humanos , Armazenamento e Recuperação da Informação/tendências , Bibliotecas Médicas/tendências , Desenvolvimento de Coleções em Bibliotecas/tendências , National Cancer Institute (U.S.) , Estados Unidos
7.
J Perianesth Nurs ; 33(4): 399-406, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30077281

RESUMO

PURPOSE: To measure the feasibility of a communication application and an iPad to facilitate communication in postoperative patients with head and neck cancer. DESIGN: A prospective feasibility study. METHODS: This IRB-approved study was conducted in the postanesthesia care unit at an urban comprehensive cancer center. The participants included patients with head and neck cancer who underwent surgery that resulted in altered communication. Questionnaires were developed and administered to measure feasibility and patient satisfaction at different time points (preoperative, postoperative, and 1 to 4 days postoperatively). FINDINGS: Of 38 patients in the study, 25 (66%) were able to use the customized iPad. Of these 25 patients, 15 (60%) were satisfied or somewhat satisfied with it. 84% found the customized iPad to be very or somewhat helpful for communication after surgery. CONCLUSIONS: Patients were satisfied with the customized iPad, and the study found that using technology such as this was feasible in the immediate postoperative period.


Assuntos
Comunicação , Neoplasias de Cabeça e Pescoço/fisiopatologia , Microcomputadores , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Estudos Prospectivos
8.
Med Ref Serv Q ; 36(3): 229-239, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28714820

RESUMO

Research informationists at a comprehensive cancer center sought to evaluate the impact and value of mediated literature searches in support of their users' work activities. An assessment tool was identified in the literature and modified by the investigators to solicit feedback from library users and identify the major reason(s) why scientists and health care professionals request literature searches, how they use the resulting information, and the impact that the results may or may not have on their research or patient care/decision-making activities. Survey results were qualitatively analyzed, and future avenues of outreach and promotion of mediated literature search services were identified.


Assuntos
Institutos de Câncer , Armazenamento e Recuperação da Informação , Pesquisa Biomédica , Humanos , Comportamento de Busca de Informação , Pesquisadores
9.
Fungal Genet Biol ; 98: 23-34, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27876630

RESUMO

Based on genomic analysis, polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) pathways account for biosynthesis of the majority of the secondary metabolites produced by the entomopathogenic fungus Metarhizium robertsii. To evaluate the contribution of these pathways to M. robertsii fitness and/or virulence, mutants deleted for mrpptA, the Sfp-type 4' phosphopantetheinyl transferase gene required for their activation were generated. ΔmrpptA strains were deficient in PKS and NRPS activity resulting in colonies that lacked the typical green pigment and failed to produce the nonribosomal peptides (destruxins, serinocylins, and the siderophores ferricrocin and metachelins) as well as the hybrid polyketide-peptides (NG-39x) that are all produced by the wild type (WT) M. robertsii. The ΔmrpptA colonies were also auxotrophic for lysine. Two other mutant strains were generated: ΔmraarA, in which the α-aminoadipate reductase gene critical for lysine biosynthesis was disrupted, and ΔmrsidA, in which the L-ornithine N5-oxygenase gene that is critical for hydroxamate siderophore biosynthesis was disrupted. The phenotypes of these mutants were compared to those of ΔmrpptA to separate effects of the loss of lysine or siderophore production from the overall effect of losing all polyketide and non-ribosomal peptide production. Loss of lysine biosynthesis marginally increased resistance to H2O2 while it had little effect on the sensitivity to the cell wall disruptor sodium dodecyl sulfate (SDS) and no effect on sensitivity to iron deprivation. In contrast, combined loss of metachelin and ferricrocin through the inactivation of mrsidA resulted in mutants that were as hypersensitive or slightly more sensitive to H2O2, iron deprivation, and SDS, and were either identical or marginally higher in ΔmrpptA strains. In contrast to ΔmrpptA, loss of mrsidA did not completely abolish siderophore activity, which suggests the production of one or more non-hydroxamate iron-chelating compounds. Deletion of mrpptA, mrsidA, and mraarA reduced conidium production and conidia of a GFP-tagged ΔmrpptA strain displayed a longer germination delay than WT on insect cuticles, a deficiency that was rescued by lysine supplementation. Compared with WT, ΔmrpptA strains displayed ∼19-fold reduction in virulence against Drosophila suzukii. In contrast, lysine auxotrophy and loss of siderophores accounted for ∼2 and ∼6-fold decreases in virulence, respectively. Deletion of mrpptA had no significant effect on growth inhibition of Bacillus cereus. Our results suggest that PKS and NRPS metabolism plays a significant role in M. robertsii virulence, depresses conidium production, and contributes marginally to resistance to oxidative stress and iron homeostasis, but has no significant antibacterial effect.


Assuntos
Proteínas Fúngicas/genética , Lisina/genética , Metarhizium/genética , Peptídeo Sintases/genética , Policetídeo Sintases/genética , Animais , Drosophila/microbiologia , Proteínas Fúngicas/metabolismo , Ferro/metabolismo , Lisina/biossíntese , Metarhizium/metabolismo , Metarhizium/patogenicidade , Mutação , Estresse Oxidativo/genética , Peptídeo Sintases/metabolismo , Policetídeo Sintases/metabolismo , Metabolismo Secundário/genética , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/patogenicidade
10.
Health Informatics J ; 23(3): 208-217, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-27146841

RESUMO

The information services offered by Embedded Librarians over the years have led to the more modern-and domain knowledge-specific-role of the Informationist. A 10-point questionnaire was developed and used to interview 12 attending physicians and three fellows chosen at random. The participants are either on the research track (n = 3) or the clinical track (n = 9). A two-part schematic was also created to capture more detailed feedback about the information needs and information-seeking behavior of clinicians regarding patient care (clinical) and research activities. Bibliographic management tool use and time-related factors were also captured in the interviews and written schematics. The role of the Informationist is an emerging, yet valuable one to assigned clinical groups. Clinician's knowledge-base, current awareness, productivity, and evidence-based care can be improved by use of Informationist services.


Assuntos
Neoplasias da Mama/diagnóstico , Diagnóstico por Imagem/tendências , Comportamento de Busca de Informação , Avaliação das Necessidades , Médicos/psicologia , Mama/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Humanos , Disseminação de Informação/métodos , Serviços de Informação/normas , Bibliotecários , Médicos/tendências , Pesquisa Qualitativa , Inquéritos e Questionários , Centros de Atenção Terciária/organização & administração
11.
Clin J Oncol Nurs ; 20(5): 474-6, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27668366

RESUMO

For patients with head and neck cancer, altered communication is a frequently occurring and highly upsetting issue that has been associated with psychological distress, fear, and anger among those with temporary or permanent speech impairment postsurgery. Many postoperative patients express that the most terrifying situation is to wake up from surgery and not be able to speak. Mobile devices have become part of everyday life, and augmentative and alternative communication mobile applications have the potential to enhance the healthcare journey of the patient and provider.



Assuntos
Telefone Celular , Auxiliares de Comunicação para Pessoas com Deficiência , Neoplasias de Cabeça e Pescoço/reabilitação , Distúrbios da Voz/reabilitação , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Invenções , Masculino , Pessoa de Meia-Idade
12.
Sci Rep ; 6: 23122, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26975455

RESUMO

Nematophagous fungi employ three distinct predatory strategies: nematode trapping, parasitism of females and eggs, and endoparasitism. While endoparasites play key roles in controlling nematode populations in nature, their application for integrated pest management is hindered by the limited understanding of their biology. We present a comparative analysis of a high quality finished genome assembly of Drechmeria coniospora, a model endoparasitic nematophagous fungus, integrated with a transcriptomic study. Adaptation of D. coniospora to its almost completely obligate endoparasitic lifestyle led to the simplification of many orthologous gene families involved in the saprophytic trophic mode, while maintaining orthologs of most known fungal pathogen-host interaction proteins, stress response circuits and putative effectors of the small secreted protein type. The need to adhere to and penetrate the host cuticle led to a selective radiation of surface proteins and hydrolytic enzymes. Although the endoparasite has a simplified secondary metabolome, it produces a novel peptaibiotic family that shows antibacterial, antifungal and nematicidal activities. Our analyses emphasize the basic malleability of the D. coniospora genome: loss of genes advantageous for the saprophytic lifestyle; modulation of elements that its cohort species utilize for entomopathogenesis; and expansion of protein families necessary for the nematode endoparasitic lifestyle.


Assuntos
Genoma Fúngico , Hypocreales/genética , Nematoides/microbiologia , Transcriptoma , Adaptação Fisiológica , Animais , Proteínas Fúngicas/genética , Interações Hospedeiro-Patógeno , Hypocreales/fisiologia
13.
J Am Coll Health ; 64(3): 251-5, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26731678

RESUMO

OBJECTIVE: The purpose of this article is to review a crisis intervention using the developmental-ecological protocol (Collins and Collins, 2005) with a college student presenting with symptomatology of an active eating disorder. PARTICIPANTS: Participants included University Wellness Center employees responding to the crisis. METHODS: Methods include an informal review of the crisis intervention response and application of the ABCDE developmental-ecological crisis model. RESULTS: Results reported include insight into crisis intervention when university counseling and health center is not available as resources. CONCLUSIONS: ABCDE Developmental-ecological model recommendations for university faculty and staff are included.


Assuntos
Intervenção em Crise/métodos , Transtornos da Alimentação e da Ingestão de Alimentos/diagnóstico , Transtornos da Alimentação e da Ingestão de Alimentos/terapia , Acontecimentos que Mudam a Vida , Estudantes/psicologia , Adaptação Psicológica , Transtornos da Alimentação e da Ingestão de Alimentos/psicologia , Feminino , Academias de Ginástica , Humanos , Avaliação das Necessidades , Resultado do Tratamento , Estados Unidos , Universidades , Adulto Jovem
14.
Fungal Genet Biol ; 82: 56-68, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26135511

RESUMO

Efficient iron acquisition mechanisms are fundamental for microbial survival in the environment and for pathogen virulence within their hosts. M. robertsii produces two known iron-binding natural products: metachelins, which are used to scavenge extracellular iron, and ferricrocin, which is strictly intracellular. To study the contribution of siderophore-mediated iron uptake and storage to M. robertsii fitness, we generated null mutants for each siderophore synthase gene (mrsidD and mrsidC, respectively), as well as for the iron uptake transcriptional repressor mrsreA. All of these mutants showed impaired germination speed, differential sensitivity to hydrogen peroxide, and differential ability to overcome iron chelation on growth-limiting iron concentrations. RT-qPCR data supported regulation of mrsreA, mrsidC, and mrsidD by supplied iron in vitro and during growth within the insect host, Spodoptera exigua. We also observed strong upregulation of the insect iron-binding proteins, transferrins, during infection. Insect bioassays revealed that ferricrocin is required for full virulence against S. exigua; neither the loss of metachelin production nor the deletion of the transcription factor mrsreA significantly affected M. robertsii virulence.


Assuntos
Metarhizium/genética , Metarhizium/metabolismo , Sideróforos/metabolismo , Animais , Evolução Molecular , Ferricromo/análogos & derivados , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Insetos/microbiologia , Espaço Intracelular , Ferro/metabolismo , Metarhizium/efeitos dos fármacos , Metarhizium/patogenicidade , Família Multigênica , Mutação , Fenótipo , Deleção de Sequência , Sideróforos/química , Virulência/genética
15.
J Chem Ecol ; 41(2): 202-11, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25653045

RESUMO

Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (V. nigrum) are two invasive plant species in the northeastern United States and eastern Canada that have undergone rapidly expanding ranges over the past 30 years. Both species possess a highly bioactive phytotoxin -(-) antofine in root tissues that causes pronounced inhibition in laboratory bioassays of native plant species co-located in habitats where swallow-wort is found. To further evaluate the allelopathic potential of -(-) antofine, we: determined its concentration in young plant tissues; used in situ approaches to assess antofine stability, potential activity of degradation products, activity in sterile and nonsterile soil; and determined accumulation and concentration in hydroponic cultivation and field collected soil samples. Extracts of seeds and young seedlings were found to have approximately 2-3 times the level of -(-) antofine in comparison to root extracts of adult plants. Breakdown products of antofine accumulated rapidly with exposure to light, but more slowly in the dark, at ambient temperatures, and these products did not retain biological activity. Extraction efficiencies of control soil spiked with -(-) antofine were low but easily detectable by HPLC. Soil samples collected over two growing seasons at four different sites where either pale swallow-wort or black swallow-wort populations are present were negative for the presence of -(-) antofine. Dose response curves using sterile and nonsterile soil spiked with -(-) antofine demonstrated a requirement for at least 20-55 × greater -(-) antofine concentrations in soil to produce similar phytotoxic effects to those previously seen in agar bioassays with lettuce seedlings. Sterile soil had a calculated EC50 of 686 µM (250 µg/g) as compared to nonsterile soil treatments with a calculated EC50 of 1.88 mM (640 µg/g). When pale swallow-wort and black swallow-wort adult plants were grown in hydroponic cultivation, -(-) antofine was found in root exudates and in the growing medium in the nM range. The concentrations in exudate were much lower than that needed for biological activity (µM) although they might be an underestimate of what may accumulate over time in an undisturbed rhizosphere. Based on these various results, it remains uncertain as to whether -(-) antofine could play a significant allelopathic role for invasive swallow-worts.


Assuntos
Indóis/química , Fenantrolinas/química , Rizosfera , Solo/química , Vincetoxicum/química , Cynanchum/química , Espécies Introduzidas , New York
16.
J Mol Biol ; 427(6 Pt B): 1451-1463, 2015 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-25591491

RESUMO

Heterologous expression of many proteins in bacteria, yeasts, and plants is often limited by low titers of functional protein. To address this problem, we have created a two-tiered directed evolution strategy in Escherichia coli that enables optimization of protein production while maintaining high biological activity. The first tier involves a genetic selection for intracellular protein stability that is based on the folding quality control mechanism inherent to the twin-arginine translocation pathway, while the second is a semi-high-throughput screen for protein function. To demonstrate the utility of this strategy, we isolated variants of the endoglucanase Cel5A, from the plant-pathogenic fungus Fusarium graminearum, whose production was increased by as much as 30-fold over the parental enzyme. This gain in production was attributed to just two amino acid substitutions, and it was isolated after two iterations through the two-tiered approach. There was no significant tradeoff in activity on soluble or insoluble cellulose substrates. Importantly, by combining the folding filter afforded by the twin-arginine translocation quality control mechanism with a function-based screen, we show enrichment for variants with increased protein abundance in a manner that does not compromise catalytic activity, providing a highly soluble parent for engineering of improved or new function.


Assuntos
Celulase/metabolismo , Proteínas de Escherichia coli , Fusarium/enzimologia , Proteínas de Membrana Transportadoras , Engenharia de Proteínas , Dobramento de Proteína , Controle de Qualidade , Arginina/química , Celulase/genética , Celulase/isolamento & purificação , Escherichia coli/enzimologia , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Fusariose/metabolismo , Fusariose/microbiologia , Fusarium/crescimento & desenvolvimento , Mutação/genética , Estabilidade Proteica , Solubilidade
17.
Nat Prod Rep ; 31(10): 1287-305, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25148015

RESUMO

This highlight discusses the secondary metabolite potential of the insect pathogens Metarhizium and Beauveria, including a bioinformatics analysis of secondary metabolite genes for which no products are yet identified.


Assuntos
Fungos , Fungos/química , Fungos/genética , Fungos/metabolismo , Humanos , Estrutura Molecular
18.
J Nat Prod ; 77(7): 1685-92, 2014 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-24992511

RESUMO

Under iron-depleted culture conditions, the entomopathogenic fungus Metarhizium robertsii (Bischoff, Humber, and Rehner) (= M. anisopliae) produces a complex of extracellular siderophores including novel O-glycosylated and N-oxidized coprogen-type compounds as well as the known fungal siderophores N(α)-dimethylcoprogen (NADC) and dimerumic acid (DA). Metachelin A (1), the most abundant component in the M. robertsii siderophore mixture, was characterized as a 1094 Da analogue of NADC that is O-glycosylated by ß-mannose at both terminal hydroxyl groups and N-oxidized at the dimethylated α-nitrogen. The mixture also contained a 1078 Da analogue, metachelin B (2), which lacks the N-oxide modification. Also characterized were the aglycone of 1, i.e., the N-oxide of NADC (3), and the monomannoside of DA (6). N-Oxide and O-glycosyl substituents are unprecedented among microbial siderophores. At high ESIMS source energy and at room temperature in DMSO, 1 underwent Cope elimination, resulting in loss of the N(α)-dimethyl group and dehydration of the α-ß bond. High-resolution ESIMS data confirmed that all tri- and dihydroxamate siderophores (1-6) complex with trivalent Fe, Al, and Ga. In a chrome azurol S assay, all of the M. robertsii siderophores showed iron-binding activity roughly equivalent to that of desferrioxamine B.


Assuntos
Compostos Férricos/isolamento & purificação , Ferro/metabolismo , Manosídeos/isolamento & purificação , Metarhizium/química , Sideróforos/química , Transporte Biológico , Dicetopiperazinas/química , Espectroscopia de Ressonância de Spin Eletrônica , Compostos Férricos/química , Compostos Férricos/farmacologia , Ácidos Hidroxâmicos/química , Hidroxibenzoatos , Manosídeos/química , Manosídeos/farmacologia , Estrutura Molecular , Oxirredução , Sideróforos/farmacologia
19.
Mol Plant Microbe Interact ; 27(8): 793-808, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24762221

RESUMO

Iron is an essential nutrient and prudent iron acquisition and management are key traits of a successful pathogen. Fungi use nonribosomally synthesized secreted iron chelators (siderophores) or reductive iron assimilation (RIA) mechanisms to acquire iron in a high affinity manner. Previous studies with the maize pathogen Cochliobolus heterostrophus identified two genes, NPS2 and NPS6, encoding different nonribosomal peptide synthetases responsible for biosynthesis of intra- and extracellular siderophores, respectively. Deletion of NPS6 results in loss of extracellular siderophore biosynthesis, attenuated virulence, hypersensitivity to oxidative and iron-depletion stress, and reduced asexual sporulation, while nps2 mutants are phenotypically wild type in all of these traits but defective in sexual spore development when NPS2 is missing from both mating partners. Here, it is reported that nps2nps6 mutants have more severe phenotypes than both nps2 and nps6 single mutants. In contrast, mutants lacking the FTR1 or FET3 genes encoding the permease and ferroxidase components, respectively, of the alternate RIA system, are like wild type in all of the above phenotypes. However, without supplemental iron, combinatorial nps6ftr1 and nps2nps6ftr1 mutants are less virulent, are reduced in growth, and are less able to combat oxidative stress and to sporulate asexually, compared with nps6 mutants alone. These findings demonstrate that, while the role of RIA in metabolism and virulence is overshadowed by that of extracellular siderophores as a high-affinity iron acquisition mechanism in C. heterostrophus, it functions as a critical backup for the fungus.


Assuntos
Ascomicetos/fisiologia , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Ferro/metabolismo , Doenças das Plantas/microbiologia , Zea mays/microbiologia , Ascomicetos/citologia , Ascomicetos/genética , Ascomicetos/patogenicidade , Ceruloplasmina/genética , Ceruloplasmina/metabolismo , Proteínas Fúngicas/metabolismo , Homeostase , Peróxido de Hidrogênio/metabolismo , Ferro/farmacologia , Deficiências de Ferro , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Oxirredução , Estresse Oxidativo , Peptídeo Sintases/genética , Peptídeo Sintases/metabolismo , Fenótipo , Folhas de Planta/citologia , Folhas de Planta/microbiologia , Sideróforos/isolamento & purificação , Sideróforos/metabolismo , Esporos Fúngicos , Virulência , Zea mays/citologia
20.
J Bacteriol ; 195(2): 287-96, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23144243

RESUMO

Pseudomonas syringae pv. tomato DC3000 produces the phytotoxin coronatine, a major determinant of the leaf chlorosis associated with DC3000 pathogenesis. The DC3000 PSPTO4723 (cmaL) gene is located in a genomic region encoding type III effectors; however, it promotes chlorosis in the model plant Nicotiana benthamiana in a manner independent of type III secretion. Coronatine is produced by the ligation of two moieties, coronafacic acid (CFA) and coronamic acid (CMA), which are produced by biosynthetic pathways encoded in separate operons. Cross-feeding experiments, performed in N. benthamiana with cfa, cma, and cmaL mutants, implicate CmaL in CMA production. Furthermore, analysis of bacterial supernatants under coronatine-inducing conditions revealed that mutants lacking either the cma operon or cmaL accumulate CFA rather than coronatine, supporting a role for CmaL in the regulation or biosynthesis of CMA. CmaL does not appear to regulate CMA production, since the expression of proteins with known roles in CMA production is unaltered in cmaL mutants. Rather, CmaL is needed for the first step in CMA synthesis, as evidenced by the fact that wild-type levels of coronatine production are restored to a ΔcmaL mutant when it is supplemented with 50 µg/ml l-allo-isoleucine, the starting unit for CMA production. cmaL is found in all other sequenced P. syringae strains with coronatine biosynthesis genes. This characterization of CmaL identifies a critical missing factor in coronatine production and provides a foundation for further investigation of a member of the widespread DUF1330 protein family.


Assuntos
Aminoácidos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Indenos/metabolismo , Isoleucina/metabolismo , Pseudomonas syringae/enzimologia , Deleção de Genes , Redes e Vias Metabólicas/genética , Doenças das Plantas/microbiologia , Pseudomonas syringae/genética , Pseudomonas syringae/metabolismo , Nicotiana/microbiologia
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