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1.
Indian J Orthop ; 55(Suppl 1): 110-118, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34122763

RESUMO

BACKGROUND: Hallux valgus is a common foot deformity that leads to functional disability with serious sequelae. Minimally invasive surgery is often used to treat hallux valgus in order to reduce wound complications and improve recovery time. The objective of this study was to compare a Simple, Effective, Rapid, Inexpensive (SERI) technique with a simple Chevron technique in patients with minimum of 1-year follow-up. METHODS AND MATERIALS: Between the years 2014-2015, we performed a prospective study comparing the SERI minimally invasive technique to treat symptomatic hallux valgus with a standard chevron osteotomy technique. All procedures were performed by a single fellowship trained foot and ankle surgeon. Twenty-one patients were randomized to the SERI cohort and 15 to the standard Chevron technique. RESULTS: The mean preoperative intermetatarsal angle (IMA) of the SERI group was 14.8 ± 1.9 (11.9-22.9). The mean preoperative IMA of the Chevron control group was 13.3 ± 2.3 (10.4-18.2) (p = 0.038). The mean IMA two weeks after the surgery was 6.0 ± 2.3 (2.4-12) in the SERI group, and 6.1 ± 3 (2.6-13.1) in the control group. At the two-week and 1-year follow-up, there was no significant difference found in the IMA between the two groups (p = 0.871). The mean hallux valgus angle reduction was 11.85 ± 4.88 (3-20.8) and 11.09 ± 6.51 (- 1.1 to 22.5) in the SERI and Chevron groups, respectively (p = 0.69). Neither groups reported symptomatic transfer metatarsalgia throughout the follow-up period. The SERI group had increased metatarsophalangeal joint (MTPJ) motion (p < 0.001); however, all other parameters with similar. CONCLUSION: The SERI technique provided comparable outcomes at up to 1-year follow-up when compared with a standard Chevron osteotomy for moderate hallux valgus. This study demonstrated good reproducible results using the SERI technique for moderate hallux valgus. LEVEL OF EVIDENCE: Level II Prospective Study. TRIAL REGISTRATION: Approved by local IRB at MMC.

2.
Phytopathology ; 110(4): 708-722, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31821114

RESUMO

Effective altruism is an ethical framework for identifying the greatest potential benefits from investments. Here, we apply effective altruism concepts to maximize research benefits through identification of priority stakeholders, pathosystems, and research questions and technologies. Priority stakeholders for research benefits may include smallholder farmers who have not yet attained the minimal standards set out by the United Nations Sustainable Development Goals; these farmers would often have the most to gain from better crop disease management, if their management problems are tractable. In wildlands, prioritization has been based on the risk of extirpating keystone species, protecting ecosystem services, and preserving wild resources of importance to vulnerable people. Pathosystems may be prioritized based on yield and quality loss, and also factors such as whether other researchers would be unlikely to replace the research efforts if efforts were withdrawn, such as in the case of orphan crops and orphan pathosystems. Research products that help build sustainable and resilient systems can be particularly beneficial. The "value of information" from research can be evaluated in epidemic networks and landscapes, to identify priority locations for both benefits to individuals and to constrain regional epidemics. As decision-making becomes more consolidated and more networked in digital agricultural systems, the range of ethical considerations expands. Low-likelihood but high-damage scenarios such as generalist doomsday pathogens may be research priorities because of the extreme potential cost. Regional microbiomes constitute a commons, and avoiding the "tragedy of the microbiome commons" may depend on shifting research products from "common pool goods" to "public goods" or other categories. We provide suggestions for how individual researchers and funders may make altruism-driven research more effective.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.


Assuntos
Altruísmo , Ecossistema , Agricultura , Produtos Agrícolas , Humanos , Doenças das Plantas
3.
Plant Dis ; 98(12): 1666-1670, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30703875

RESUMO

During the summers of 2012 and 2013, 39 tomato (Solanum lycopersicum) lines or varieties were evaluated for resistance to late blight in three separate field trials. In each trial, late blight was caused by field isolates of Phytophthora infestans clonal lineage US-23. Varieties with the late blight resistance genes Ph-1, Ph-2, Ph-3, and Ph-2 + Ph-3 were included, along with several heirloom varieties with grower-reported resistance and varieties with no known resistance. All six varieties with Ph-2 + Ph-3, along with NC25P, which is homozygous for Ph-3 only, showed a high level of resistance. Plum Regal F1, which is heterozygous for Ph-3 only, showed moderate resistance. Legend, the only variety with Ph-2 alone, also showed moderate resistance. Three heirloom varieties, Matt's Wild Cherry, Lemon Drop, and Mr. Stripey, showed a high level of resistance comparable with that of varieties with Ph-2 + Ph-3. New Yorker, possessing Ph-1 only, showed no resistance. Indeterminate varieties had significantly less disease than determinate varieties in two of the three trials. Overall, this study suggests that tomato varieties with both Ph-2 and Ph-3 can be used to effectively manage late blight caused by P. infestans clonal lineage US-23. Varieties possessing only Ph-2, or heterozygous for Ph-3, were better protected than those without any late blight resistance but might still require supplemental fungicide applications, while the variety that was homozygous for Ph-3 was highly resistant. Several heirloom varieties were also highly resistant, and the unknown mechanism of their resistance warrants further research. Finally, the plasticity observed in United States P. infestans populations over the past several decades necessitates continued monitoring for genetic changes within P. infestans that could lead to the breakdown of resistance reported here.

4.
Clin Exp Allergy ; 43(8): 928-40, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23889246

RESUMO

BACKGROUND: Pollen-food syndrome (PFS), a food allergy affecting pollen-sensitized individuals, is likely to be the most prevalent food allergy in adults, estimated to affect 50-90% of people allergic to birch tree pollen. OBJECTIVE: A validated PFS diagnostic questionnaire (PFSDQ2) was used to determine the prevalence of PFS and also to characterize those who report reactions to foods. METHODS: Five UK General practices each sent the PFSDQ2 by post to 2000 patients aged 18-75 years randomly selected from their practice database. The validated questionnaire was accompanied by an additional set of questions to ascertain the demographic of the population, the foods involved and the age of onset. RESULTS: There were 3590 subjects who returned completed questionnaires, with an average return rate from each practice of 36% (range 22-47%). Of these, 73 were diagnosed with PFS according to the questionnaire (PFS+ve) giving a population prevalence of 2%. A further 482 subjects reported reactions to foods but did not fulfil the diagnostic criteria for PFS. The greatest prevalence of PFS was in the Croydon (SE England) urban practice (4.1%) and the lowest in the Aberdeen (Scotland) urban practice (0.8%) (P < 0.001).The most frequently reported trigger foods were apples, hazelnuts and kiwifruit and the majority of those with PFS first experienced symptoms below the age of 20 years. PFS+ve subjects were also more likely to be female and have a higher socio-economic status than those who did not report reactions to foods. CONCLUSIONS: The UK prevalence of PFS was 2%, although this varied according to the location of the practice population. The majority of PFS+ve subjects first reported symptoms in their teens. The reported age of onset has important implications for the diagnosis of primary and cross-reactive peanut and tree nut allergies in teenagers and young adults. The continuing rise in aeroallergen sensitization is likely to result in an increased frequency of PFS presenting in both primary and secondary care.


Assuntos
Hipersensibilidade Alimentar/epidemiologia , Rinite Alérgica Sazonal/epidemiologia , Adolescente , Adulto , Idade de Início , Idoso , Alimentos/efeitos adversos , Hipersensibilidade Alimentar/diagnóstico , Geografia , Humanos , Pessoa de Meia-Idade , Pólen/imunologia , Prevalência , Vigilância em Saúde Pública , Rinite Alérgica Sazonal/diagnóstico , Inquéritos e Questionários , Reino Unido/epidemiologia , Adulto Jovem
5.
Plant Dis ; 97(3): 296-306, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30722376

RESUMO

The tomato late blight pandemic of 2009 made late blight into a household term in much of the eastern United States. Many home gardeners and many organic producers lost most if not all of their tomato crop, and their experiences were reported in the mainstream press. Some CSAs (Community Supported Agriculture) could not provide tomatoes to their members. In response, many questions emerged: How did it happen? What was unusual about this event compared to previous late blight epidemics? What is the current situation in 2012 and what can be done? It's easiest to answer these questions, and to understand the recent epidemics of late blight, if one knows a bit of the history of the disease and the biology of the causal agent, Phytophthora infestans.

6.
Plant Dis ; 97(7): 873-881, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30722527

RESUMO

Phytophthora infestans, the causal agent of late blight disease, has been reported in the United States and Canada since the mid-nineteenth century. Due to the lack of or very limited sexual reproduction, the populations of P. infestans in the United States are primarily reproducing asexually and, thus, show a simple genetic structure. The emergence of new clonal lineages of P. infestans (US-22, US-23, and US-24) responsible for the late blight epidemics in the northeastern region of the United States in the summers of 2009 and 2010 stimulated an investigation into phenotypic traits associated with these genotypes. Mating type, differences in sensitivity to mefenoxam, differences in pathogenicity on potato and tomato, and differences in rate of germination were studied for clonal lineages US-8, US-22, US-23, and US-24. Both A1 and A2 mating types were detected. Lineages US-22, US-23, and US-24 were generally sensitive to mefenoxam while US-8 was resistant. US-8 and US-24 were primarily pathogenic on potato while US-22 and US-23 were pathogenic on both potato and tomato. Indirect germination was favored at lower temperatures (5 and 10°C) whereas direct germination, though uncommon, was favored at higher temperatures (20 and 25°C). Sporangia of US-24 released zoospores more rapidly than did sporangia of US-22 and US-23. The association of characteristic phenotypic traits with genotype enables the prediction of phenotypic traits from rapid genotypic analyses for improved disease management.

7.
Plant Dis ; 96(6): 881-888, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30727350

RESUMO

Fusarium ear rot of maize, caused by Fusarium verticillioides, is an important disease affecting maize production worldwide. Apart from reducing yield and grain quality, F. verticillioides produces fumonisins which have been associated with mycotoxicoses of animals and humans. Currently, no maize breeding lines are known with resistance to F. verticillioides in South Africa. The objective of this study, therefore, was to evaluate 24 genetically diverse maize inbred lines as potential sources of resistance to Fusarium ear rot and fumonisin accumulation in field trials at Potchefstroom and Vaalharts in South Africa. After artificial silk channel inoculation with F. verticillioides, Fusarium ear rot development was determined at harvest and fumonisins B1, B2, and B3 quantified. A significant inbred line by location effect was observed for Fusarium ear rot severity (P ≤ 0.001), although certain lines proved to be consistently resistant across both locations. The individual inbred lines also differed considerably in fumonisin accumulation between Potchefstroom and Vaalharts, with differentiation between susceptible and potentially resistant inbred lines only being possible at Vaalharts. A greenhouse inoculation trial was then also performed on a subset of potentially resistant and highly susceptible lines. The inbred lines CML 390, CML 444, CML 182, VO 617Y-2, and RO 549 W consistently showed a low Fusarium ear rot (<5%) incidence at both Potchefstroom and Vaalharts and in the greenhouse. Two of these inbred lines, CML 390 and CML 444, accumulated fumonisin levels <5 mg kg-1. These lines could potentially act as sources of resistance for use within a maize breeding program.

8.
Biochem Soc Trans ; 35(Pt 6): 1643-7, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18031283

RESUMO

PPR (pentatricopeptide repeat) genes form a large family particularly prevalent in higher plants and targeted to organelles. They are involved in many post-transcriptional processes such as splicing, editing, processing and translation. Current data suggest that PPR proteins are involved in targeting effectors to the correct sites on the correct transcripts but the molecular mechanisms for RNA binding and effector recruitment by PPR proteins are not understood yet.


Assuntos
Organelas/genética , Proteínas de Plantas/genética , Processamento Pós-Transcricional do RNA/genética , Animais , Humanos , Organelas/metabolismo , Desenvolvimento Vegetal , Proteínas de Plantas/metabolismo , Plantas/genética , Plantas/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo
9.
Scott Med J ; 51(4): 10-4, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17137140

RESUMO

INTRODUCTION: We wished to obtain a snapshot of current service provision and how this could best be developed approximately one year on from the introduction of the National Institute for Clinical Excellence (NICE) guidelines for the management of chronic obstructive pulmonary disease (COPD) and the inclusion of COPD care in the New GMS Contract Quality and Outcomes Framework (QOF). METHODOLOGY: A questionnaire-based survey sent to every general practice (n = 84) in Grampian. RESULTS: Responses were received from 75 of 84 practices (89%). Questionnaires were returned by both general practitioners (GPs) and practice nurses in 45 practices (54%). All responding practices reported that they had COPD registers. 60/75 (80%) of practices reported having a dedicated COPD clinic; 70/75 (93%) had a spirometer. Areas identified for service development were: quality assuring training in COPD care and spirometry; expanding pulmonary rehabilitation provision (86%), delivering this service locally (54%) and in primary care (75%); standardising referral, assessment and communication about provision of home oxygen; training in pulse oximetry (71%). CONCLUSION: This data has important implications for the validity of the quality indicators (QOF) under the new GMS contract. Our respondents identified areas where the new GMS contract QOF could be improved, as well as providing useful suggestions for service development. Respondents recognised that not all clinical services can be effectively delivered by general practice with data supporting the development of intermediate care services for people with COPD.


Assuntos
Padrões de Prática Médica/estatística & dados numéricos , Atenção Primária à Saúde , Doença Pulmonar Obstrutiva Crônica/terapia , Humanos , Oximetria , Oxigenoterapia , Guias de Prática Clínica como Assunto , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Escócia , Abandono do Hábito de Fumar , Espirometria
10.
Prostate ; 66(14): 1463-73, 2006 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-16897729

RESUMO

BACKGROUND: Here we evaluate auto-antibody response against two potential antigenic determinants of genes highly expressed in low Gleason Score prostate cancer (PC) tumor samples, namely FLJ23438 and VAMP3. METHODS: RT-PCR assays were used to analyze mRNA expression profiles of FLJ23438 and VAMP3 transcripts. The auto-antibody response against FLJ23438 and VAMP3 recombinant proteins was tested by immunoblot assays using PC, benign prostate hyperplasia (BPH), healthy donors (HD), and other human cancers plasma samples. RESULTS: Our data showed that 37% (10/27) and 7.4% (2/27) of PC plasma samples presented auto-antibodies against FLJ23438 and VAMP3, respectively. Only 8.3% (1/12) of BPH plasma samples were reactive for both auto-antibodies, while none (0/12) of HD plasma samples tested were reactive. CONCLUSIONS: The prevalence of 37% of positive PC plasma samples for anti-FLJ23438 antibodies suggests that humoral immune response against this antigenic determinant could be a potential serum marker for this cancer.


Assuntos
Adenocarcinoma/imunologia , Autoanticorpos/sangue , Biomarcadores Tumorais/imunologia , Neoplasias da Próstata/imunologia , Proteína 3 Associada à Membrana da Vesícula/imunologia , Adenocarcinoma/epidemiologia , Adenocarcinoma/fisiopatologia , Idoso , Antígenos/genética , Antígenos/imunologia , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/genética , Neoplasias da Mama , Carcinoma de Células Escamosas , Linhagem Celular Tumoral , Neoplasias Colorretais , Neoplasias Esofágicas , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Pulmonares , Masculino , Pessoa de Meia-Idade , Fases de Leitura Aberta/genética , Hiperplasia Prostática/epidemiologia , Hiperplasia Prostática/imunologia , Hiperplasia Prostática/fisiopatologia , Neoplasias da Próstata/epidemiologia , Neoplasias da Próstata/fisiopatologia , RNA Mensageiro/genética , RNA Nuclear Pequeno/genética , RNA Nuclear Pequeno/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Estudos Soroepidemiológicos , Proteína 3 Associada à Membrana da Vesícula/genética
11.
Proc Inst Mech Eng H ; 217(4): 263-71, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12885196

RESUMO

The spread of fluid from a localized source on to a flat fibrous sheet is studied. The sheet is inclined at an angle, alpha, to the horizontal, and the areal flux of the fluid released is Qa. A new experimental study is described where the dimensions of the wetted region are measured as a function of time t, Qa and alpha (>0). The down-slope length, Y, grows according to Y approximately (Qa t)(2/3) (sin alpha)(1/3); for high discharge rates and low angles of inclination, the cross-slope width, X, grows as approximately (Qa t)(1/2), while for low discharge rates or high angles of inclination, the cross-slope transport is dominated by infiltration and X approximately 2(2Ks psi* t)(1/2), where Ks is the saturated permeability and psi* is the characteristic value of capillary pressure. A scaling analysis of the underlying non-linear advection diffusion equation describing the infiltration process confirms many of the salient features of the flow observed. Good agreement is observed between the collapse of the numerical solutions and experimental results. The broader implications of these results for incontinence bed-pad research are briefly discussed.


Assuntos
Tampões Absorventes para a Incontinência Urinária , Modelos Teóricos , Reologia/métodos , Têxteis , Água/química , Absorção , Simulação por Computador , Gravitação , Humanos , Teste de Materiais/métodos , Membranas Artificiais , Porosidade , Propriedades de Superfície , Incontinência Urinária/reabilitação , Viscosidade
12.
Gene ; 286(1): 21-4, 2002 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-11943456

RESUMO

Editing in plant mitochondria consists in C to U changes and mainly affects messenger RNAs, thus providing the correct genetic information for the biosynthesis of mitochondrial (mt) proteins. But editing can also affect some of the plant mt tRNAs encoded by the mt genome. In dicots, a C to U editing event corrects a C:A mismatch into a U:A base pair in the acceptor stem of mt tRNA(Phe) (GAA). In larch mitochondria, three C to U editing events restore U:A base pairs in the acceptor stem, D stem and anticodon stem, respectively, of mt tRNA(His) (GUG). For both these mt RNA(Phe) and tRNA(His), editing of the precursors is a prerequisite for their processing into mature tRNAs. In potato mt tRNA(Cys) (GCA), editing converts a C28:U42 mismatch in the anticodon stem into a U28:U42 non-canonical base pair, and reverse transcriptase minisequencing has shown that the mature mt tRNA(Cys) is fully edited. In the bryophyte Marchantia polymorpha this U residue is encoded in the mt genome and evolutionary studies suggest that restoration of a U28 residue is necessary when it is not encoded in the gene. However, in vitro studies have shown that neither processing of the precursor, nor aminoacylation of tRNA(Cys), requires C to U editing at this position. But sequencing of the purified mt tRNA(Cys) has shown that Psi is present at position 28, indicating that C to U editing is a prerequisite for the subsequent isomerization of U into Psi at position 28.


Assuntos
Mitocôndrias/genética , Plantas/genética , Edição de RNA , RNA de Transferência/genética , Citidina/genética , Citidina/metabolismo , Pseudouridina/genética , Pseudouridina/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , RNA de Transferência/metabolismo , RNA de Transferência de Cisteína/genética , RNA de Transferência de Cisteína/metabolismo , RNA de Transferência de Histidina/genética , RNA de Transferência de Histidina/metabolismo , RNA de Transferência de Fenilalanina/genética , RNA de Transferência de Fenilalanina/metabolismo , Uridina/genética , Uridina/metabolismo
13.
Biochim Biophys Acta ; 1541(1-2): 54-63, 2001 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-11750662

RESUMO

Plant cells contain two organelles originally derived from endosymbiotic bacteria: mitochondria and plastids. Their endosymbiotic origin explains why these organelles contain their own DNA, nonetheless only a few dozens of genes are actually encoded by these genomes. Many of the other genes originally present have been transferred to the nuclear genome of the host, the product of their expression being targeted back to the corresponding organelle. Although targeting of proteins to mitochondria and chloroplasts is generally highly specific, an increasing number of examples have been discovered where the same protein is imported into both organelles. The object of this review is to compare and discuss these examples in order to try and identify common features of dual-targeted proteins. The study helps throw some light on the factors determining organelle targeting specificity, and suggests that dual-targeted proteins may well be far more common than once thought.


Assuntos
Cloroplastos/metabolismo , Mitocôndrias/metabolismo , Proteínas de Plantas/metabolismo , Marcação de Genes , Proteínas de Plantas/genética , Transporte Proteico
15.
Acta Biochim Pol ; 48(2): 383-9, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11732609

RESUMO

Editing in plant mitochondria consists in C to U changes and mainly affects messenger RNAs, thus providing the correct genetic information for the biosynthesis of mitochondrial (mt) proteins. But editing can also affect some of the plant mt tRNAs encoded by the mt genome. In dicots, a C to U editing event corrects a C:A mismatch into a U:A base-pair in the acceptor stem of mt tRNAPhe (GAA). In larch mitochondria, three C to U editing events restore U:A base-pairs in the acceptor stem, D stem and anticodon stem, respectively, of mt tRNAHis (GUG). For both these mt tRNAs editing of the precursors is a prerequisite for their processing into mature tRNAs. In potato mt tRNACys (GCA), editing converts a C28:U42 mismatch in the anticodon stem into a U28:U42 non-canonical base-pair, and reverse transcriptase minisequencing has shown that the mature mt tRNACys is fully edited. In the bryophyte Marchantia polymorpha this U residue is encoded in the mt genome and evolutionary studies suggest that restoration of the U28 residue is necessary when it is not encoded in the gene. However, in vitro studies have shown that neither processing of the precursor nor aminoacylation of tRNACys requires C to U editing at this position. But sequencing of the purified mt tRNACys has shown that psi is present at position 28, indicating that C to U editing is a prerequisite for the subsequent isomerization of U into psi at position 28.


Assuntos
Plantas/genética , Plantas/metabolismo , Edição de RNA , RNA de Plantas/genética , RNA de Plantas/metabolismo , RNA de Transferência/genética , RNA de Transferência/metabolismo , RNA/genética , RNA/metabolismo , Mitocôndrias/metabolismo , Modelos Químicos , Conformação de Ácido Nucleico , RNA/química , RNA Mitocondrial , RNA de Plantas/química , RNA de Transferência/química
17.
Environ Health Perspect ; 109(6): 547-9, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11445505

RESUMO

The Aral Sea area in Central Asia has been encountering one of the world's greatest environmental disasters for more than 15 years. During that time, despite many assessments and millions of dollars spent by large, multinational organizations, little has changed. The 5 million people living in this neglected and virtually unknown part of the world are suffering not only from an environmental catastrophe that has no easy solutions but also from a litany of health problems. The region is often dismissed as a chronic problem where nothing positive can be achieved. Within this complicated context, Medecins Sans Frontieres, winner of the Nobel Peace Prize in 1999, is actively trying to assess the impact of the environmental disaster on human health to help the people who live in the Aral Sea area cope with their environment. Medecins Sans Frontieres has combined a direct medical program to improve the health of the population while conducting operational research to gain a better understanding of the relationship between the environmental disaster and human health outcomes. In this paper we explore the health situation of the region and the broader policy context in which it is situated, and present some ideas that could potentially be applied to many other places in the world that are caught up in environmental and human health disasters.


Assuntos
Praguicidas/efeitos adversos , Saúde Pública , Abastecimento de Água , Agricultura , Humanismo , Humanos , Cooperação Internacional , Cazaquistão , Uzbequistão , Movimentos da Água
18.
J Biol Chem ; 276(18): 15275-83, 2001 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-11278923

RESUMO

In plant mitochondria, some of the tRNAs are encoded by the mitochondrial genome and resemble their prokaryotic counterparts, whereas the remaining tRNAs are encoded by the nuclear genome and imported from the cytosol. Generally, mitochondrial isoacceptor tRNAs all have the same genetic origin. One known exception to this rule is the group of tRNA(Gly) isoacceptors in dicotyledonous plants. A mitochondrion-encoded tRNA(Gly) and at least one nucleus-encoded tRNA(Gly) coexist in the mitochondria of these plants, and both are required to allow translation of all four GGN glycine codons. We have taken advantage of this atypical situation to address the problem of tRNA/aminoacyl-tRNA synthetase coevolution in plants. In this work, we show that two different nucleus-encoded glycyl-tRNA synthetases (GlyRSs) are imported into Arabidopsis thaliana and Phaseolus vulgaris mitochondria. The first one, GlyRS-1, is similar to human or yeast glycyl-tRNA synthetase, whereas the second, GlyRS-2, is similar to Escherichia coli glycyl-tRNA synthetase. Both enzymes are dual targeted, GlyRS-1 to mitochondria and to the cytosol and GlyRS-2 to mitochondria and chloroplasts. Unexpectedly, GlyRS-1 seems to be active in the cytosol but inactive in mitochondrial fractions, whereas GlyRS-2 is likely to glycylate both the organelle-encoded tRNA(Gly) and the imported tRNA(Gly) present in mitochondria.


Assuntos
Arabidopsis/enzimologia , Fabaceae/enzimologia , Glicina-tRNA Ligase/metabolismo , Plantas Medicinais , Sequência de Aminoácidos , Sequência de Bases , Western Blotting , Cromatografia Líquida , DNA de Plantas , Escherichia coli/genética , Glicina-tRNA Ligase/genética , Mitocôndrias/enzimologia , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Frações Subcelulares/enzimologia , Especificidade por Substrato
19.
Plant J ; 22(5): 439-47, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10849359

RESUMO

The effect of alteration of 5' and 3' flanking sequences on the transcription of plant tRNA genes was analysed using an RNA polymerase III-dependent in vitro transcription system derived from nuclei of cultured tobacco cells. A TATA-like sequence and the CAA motif frequently observed upstream of plant tRNA genes, and the poly(T) stretch usually present downstream, were shown to be necessary for efficient re-initiation of transcription. The CAA motif was shown to be a transcription initiation site. Introduction of the CAA and TATA-like motifs into a gene naturally lacking them greatly enhanced transcription by promoting efficient re-initiation.


Assuntos
Genes de Plantas , RNA de Transferência de Serina/genética , TATA Box , Regiões Terminadoras Genéticas/genética , Transcrição Gênica/genética , Sequência de Bases , Dados de Sequência Molecular , Mutação , Plantas Tóxicas , Deleção de Sequência , Nicotiana/genética
20.
J Biol Chem ; 275(18): 13291-6, 2000 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-10788435

RESUMO

It has often been suggested that precursors to mitochondrial aminoacyl-tRNA synthetases are likely carriers for mitochondrial import of tRNAs in those organisms where this process occurs. In plants, it has been shown that mutation of U(70) to C(70) in Arabidopsis thaliana tRNA(Ala)(UGC) blocks aminoacylation and also prevents import of the tRNA into mitochondria. This suggests that interaction of tRNA(Ala) with alanyl-tRNA synthetase (AlaRS) is necessary for import to occur. To test whether this interaction is sufficient to drive import, we co-expressed A. thaliana tRNA(Ala)(UGC) and the precursor to the A. thaliana mitochondrial AlaRS in Saccharomyces cerevisiae. The A. thaliana enzyme and its cognate tRNA were correctly expressed in yeast in vivo. However, although the plant AlaRS was efficiently imported into mitochondria in the transformed strains, we found no evidence for import of the A. thaliana tRNA(Ala) nor of the endogenous cytosolic tRNA(Ala) isoacceptors. We conclude that at least one other factor besides the mitochondrial AlaRS precursor must be involved in mitochondrial import of tRNA(Ala) in plants.


Assuntos
Alanina-tRNA Ligase/biossíntese , Mitocôndrias/metabolismo , Aminoacil-RNA de Transferência/metabolismo , Alanina-tRNA Ligase/genética , Arabidopsis/enzimologia , Arabidopsis/genética , Transporte Biológico , Regulação Fúngica da Expressão Gênica , Técnicas de Transferência de Genes , Mitocôndrias/genética , Aminoacil-RNA de Transferência/genética , Saccharomyces cerevisiae
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