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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Phenotypic and genotypic characterization and comparison of Edwardsiella ictaluri isolates derived from catfish and ornamental fish species

Divya, Divya 06 August 2021 (has links) (PDF)
The gram-negative bacteria Edwardsiella ictaluri causes significant economic losses in aquacultured fish. Generally considered host-specific to catfish, there are reports of E. ictaluri outbreaks from other aquacultured species, including ornamental fish raised in the southeastern U.S. Thus, a comprehensive phenotypic and genotypic characterization of E. ictaluri isolates from catfish and ornamental aquaculture was warranted. Morphological, biochemical, and protein profiles of catfish and ornamental derived isolates were mostly similar. Plasmid profiles of wild-type isolates were consistent within groups. Analysis of putative anti-microbial resistant isolates from catfish revealed the presence of multi-drug resistant plasmids. Genomic comparisons indicated marked differences among host groups, including unique T4SSs and phage elements among ornamental fish-derived E. ictaluri isolates. An optimal MLSA scheme consisting of eight reference genes was defined, revealing isolates from catfish and ornamental aquaculture form two discrete phyletic lineages. This study advances our understanding of E. ictaluri affecting two important agricultural commodities in the U.S.
32

Estabilidade em análise de agrupamento via modelo AMMI com reamostragem \"bootstrap\" / Stability in clustering analysis through the AMMI methodology with bootstrap

Godoi, Débora Robert de 11 October 2013 (has links)
O objetivo deste trabalho é propor uma nova metodologia de interpretação da estabilidade dos métodos de agrupamento, para dados de vegetação, utilizando a metodologia AMMI e a reamostragem (bootstrap), para ganhar confiabilidade nos agrupamentos formados. Os dados utilizados são provenientes do departamento de genética da Escola Superior de Agricultura \"Luiz de Queiroz\", e visam à produtividade de soja. Primeiramente aplica-se a metodologia AMMI e então, é estimada a matriz de distâncias euclidianas - com base nos dados originais e obtidos via reamostragem (bootstrap) - para a aplicação dos métodos de agrupamento (vizinho mais próximo, vizinho mais distante, ligação média, centroide, mediana e Ward). Para a verificação da validade dos agrupamentos formados utiliza-se o coeficiente de correlação cofenética, e pelo teste de Mantel, é apresentada a distribuição empírica dos coeficientes de correlação cofenética. Os agrupamentos obtidos pelos diferentes métodos são, em sua maioria, semelhantes indicando que, em princípio, qualquer um desses métodos seria adequado para a representação. O método que apresenta resultados discrepantes em relação aos outros (tanto para os dados originais, quanto pelos dados obtidos via bootstrap) - na representação gráfica em dendrograma - é método de Ward. Este estudo é promissor na análise da validade de agrupamentos formados em dados de vegetação. / The objective of this work is to propose a new interpretation methodology of clustering methods for vegetation data stability, using the AMMI and bootstrap methodology, to gain reliability in the clusters formed. The database used is from the Departament of Genetics of Luiz de Queiroz College of Agriculture, aiming soybean yield. Firstly AMMI is applied, then the Euclidian distance matrix is estimated - based on the original data and on the acquired by the bootstrap method - for the application of clustering methods (nearest neighbor, furthest neighbor, average linkage, centroid , median and Ward). In order to assess the validity of clusters formed the cophenetic correlation coefficient is used, and the Mantel test, in order to show the empirical distribution of the cophenetic correlation coefficients. The clusters obtained by different methods are, in most cases, quite similar, indicating that in principle, any of these methods would be suitable for the representation. The method that presents discrepant results (for both the original and bootstrap method obtained data) - on the dendrogram graphical representation, compared to the others - is the Ward\'s. This study is promising in the analysis of validity of clusters formed in vegetation data.
33

Micronutrientes e metais pesados tóxicos: do fertilizante ao produto agrícola / Micronutrients and toxic heavy metals: from fertilizer to agricultural product

Moraes, Milton Ferreira de 27 April 2009 (has links)
A presença de metais pesados tóxicos em fertilizantes tem sido motivo de preocupação e apontada como um dos obstáculos à produção sustentável de alimentos. Por outro lado, há uma crescente busca por produtos agrícolas de melhor qualidade, com maior teor de micronutrientes e menos fatores antinutricionais, como os metais pesados tóxicos. No Brasil, há poucos trabalhos relacionando fertilização e qualidade dos produtos agrícolas, em termos de micronutrientes e metais pesados tóxicos. Neste contexto, no presente trabalho foram realizados quatro experimentos tendo como objetivos avaliar: 1) a eficiência de métodos de extração e de quantificação simultânea de micronutrientes e de metais pesados tóxicos em fertilizantes; 2) a influência da fertilização nos teores de micronutrientes e metais pesados tóxicos no solo, nos indicadores microbiológicos, nas atividades enzimáticas em plantas e na qualidade dos produtos agrícolas; 3) a variação genotípica para teor de Cd, micronutrientes e suas relações em 35 cultivares de arroz de terras altas do Brasil; 4) a influência do estado nutricional e genotípica nos teores de Cd e 70Zn no arroz. Quando se usa reagentes e água de alta pureza, a análise de metais pesados tóxicos em amostras de fertilizantes pode ser realizada por micro-ondas ou sistema aberto, sendo que as quantificações dos elementos por ICP-MS e ICP-AES produzem resultados semelhantes. Porém, na análise dos teores naturais de Cd, Cr e Pb apenas a quantificação por ICP-MS foi adequada. Nas condições deste trabalho, tanto os subprodutos e rocha fosfática quanto os fertilizantes foram capazes de fornecer nutrientes às plantas, sem causar aumentos excessivos de metais pesados tóxicos nos solos e nos produtos agrícolas. Os indicadores microbiológicos do solo e as atividades enzimáticas em plantas de alface reagiram positivamente à fertilização. Foram identificadas variedades de arroz de terras altas com baixo e alto teor de Cd nos grãos. Os teores de Fe, Zn e Se apresentaram relações inversas ao teor de Cd. Observou-se interação entre estado nutricional da planta e genótipo no teor de Cd em grãos de arroz de terras altas cultivado em solução nutritiva. Concluiu-se que, com manejo adequado, a fertilização aumenta a produtividade e melhorar qualidade dos produtos agrícolas para alimentação humana e animal / The presence of toxic heavy metals in fertilizers has been a big concern. It has been indicated as one of the obstacles to sustainable food production. On the other hand, there is a growing demand for better-quality products, with high micronutrient content and low malnutrition factors, such as toxic heavy metals. In Brazil there are scarce number of studies regarding fertilization and the quality of agricultural products for micronutrients and toxic heavy metals. In this context, the present study, involving four experiments, was conducted with the objectives: 1) to assess the efficiency of methods to extract and quantify micronutrients and toxic heavy metals in fertilizers; 2) to study the influence of fertilization on the levels of micronutrients and toxic heavy metals in agricultural products; 3) to evaluate the genotypic variation in response to the content of Cd, micronutrients and their relations in 35 upland rice cultivars from Brazil; and 4) to determine the influence of the nutritional status and genotype on the levels of Cd and 70Zn in rice plant. The results showed that with the use of reagents and water of high purity, toxic heavy metals can be extracted for analysis by microwave or an open air system, and that quantification of the elements by ICP-MS and ICP-AES yields similar results. However, for the analysis of natural contents of Cd, Cr and Pb only ICP-MS quantification was appropriate. Further, both by-products and phosphate rock, as fertilizers were able to supply nutrients to the plants without causing excessive increases of toxic heavy metals in soil and agricultural products. Microbiological soil indicators and enzyme activities in plants responded positively to fertilization. Furthermore, results also showed that there were upland rice cultivars with low and high Cd content in the grains, and the levels of Fe, Zn and Se showed inverse relations with the Cd content. There was an interaction between plants the nutritional status and genotype for Cd content in grains of upland rice cultivars. Based on the results, it can be concluded that with adequate management, fertilization can increase crop yields and improve the quality of agricultural products for human and animal consumption
34

Estimativas de parâmetros genéticos e fenotípicos em uma população de cana-de-açúcar e estratégias de seleção / Estimates of genetic and phenotypic parameters in a population of sugarcane and strategies of selection

Barbosa, Pedro Augusto Medeiros 19 February 2016 (has links)
A seleção fenotípica é o método de seleção tradicional utilizado nos estágios iniciais de seleção na maioria dos programas de melhoramento genético de cana-de-açúcar após o desenvolvimento de uma população segregante. A maioria das variedades comerciais utilizadas atualmente deriva deste método. Recentemente tem sido propostas estratégias de seleção baseada na avaliação de famílias em gerações precoces em diversos programas de melhoramento de cana-de-açúcar ao redor do mundo, como o objetivo de melhora a resposta à seleção, bem como reduzir o tempo e custo necessários para o desenvolvimento de novas variedades. No presente estudo foram avaliadas 110 famílias de cana-de-açúcar em um delineamento em blocos ao acaso com duas repetições, no ano agrícola de 2012/2013, na Estação Experimentas da empresa CanaVialis, localizada em Conchal, SP. As parcelas consistiram de um sulco de 50 m, contendo 96 plantas (\"seedlings\"). Os seguintes caracteres foram avaliados no estágio de cana planta: diâmetro do colmo (DIA), altura do colmo (ALT) número de colmos por touceira (NCP), número de colmos por touceira na parcela total (NCT); teor de sólidos solúveis (BRIX), teor de açúcar no laboratório (POL) toneladas de cana por hectare (TCH) e toneladas de açúcar por hectare (TPH). Os resultados indicaram que a população tem grande variabilidade genética entre médias de famílias bem como dentro de famílias. Foram detectadas correlações genotípicas positivas entre TCH e os outros caracteres, bem como entre TPH e os outros caracteres. Com base nestes resultados discute-se uma estratégia de seleção com base na seleção para TPH aplicada nas médias de famílias, seguido da seleção fenotípica para ALT, DIA e NCP dentro das famílias selecionadas, priorizando NCP. / Phenotypic selection is the traditional method used in most of sugarcane breeding programs in early stages after the development of a segregante population. Most of commercial varieties grown currently were developed using this method. Recently, strategies of selection based on family evaluations at early stages have been proposed in sugarcane breeding programs of different research centers around the world, in order to improve the response to selection and to reduce the time and costs necessary to develop new varieties. In the present study 110 sugarcane families and two checks were evaluated using a randomized complete block design with two replications in the 2012/2013 growing season at CanaVialis Experimental Station located in Conchal, state of São Paulo. Plots consisted of a single row with 50 m long, containing 96 plants (seedlings). The following traits were evaluated at plant cane stage: stalk length (ALT), stalk diameter (DIA), stalk number per plant (NCP), soluble solids content (BRIX), average stalk number per plant in the plot (NCT), sugar content (POL), cane yield (TCH) and sugar yield (TPH). The results have shown that the population has enough genetic variability among family means as well as within families. Positive genotypic correlations were detected between TCH and the other traits as well as between TPH and the other traits. Based on these results, a scheme of selection was discussed based on the selection for TPH among family means followed by a phenotypic selection for ALT, DIA and NCP within the selected families, prioritizing NCP.
35

Biodiversidade de amebas de vida livre e bactérias associadas a amebas em reservatórios de água de torres de resfriamento / Biodiversity of free-living amoebae and bacteria associated with amobae in tanks water from cooling towers

Oliveira, Scheila da Silva Soares de January 2016 (has links)
Amebas de vida livre (AVL) são protozoários amplamente distribuídos na natureza e em ambientes artificiais. Alguns gêneros são oportunistas ou patogênicos, com característica anfizóica, são esses: Acanthamoeba spp., Naegleria spp., Balamuthia spp., Sappinia spp., e recentemente Vermamoeba spp. AVL podem servirem de reservatórios de várias bactérias patogênicas, uma vez que se alimentam dessas no ambiente por fagocitose, algumas espécies de bactérias após internalizadas escapam da via de degradação sobrevivem e multiplicam-se no interior das amebas. Face ao exposto, o presente trabalho objetivou isolar e identificar AVL e as bactérias associadas presentes em águas de torres de resfriamento, cuja temperatura da água varia entre 25 a 30°C (ideal para o desenvolvimento de diversos microrganismos). Amebas foram isoladas em cultivo monoxênico com Escherichia coli inativadas pelo calor. Das amostras positivas, foram realizadas Reações em Cadeia de Polimerase (PCR), utilizando oligonucleotídeos específicos para cada gênero. Os produtos das PCR foram sequenciados e as sequências geradas foram comparadas com sequências parciais de cada gene alvo depositadas no GenBank. Das 36 amostras, 33 (91,66%) foram positivas para presença de AVL, destas 15 (45,4%) foram positivas para Acanthamoeba spp., 12 (36,3%) para Naegleria spp., 6 (18,2%) para Vermamoeba spp. Dos endossimbiontes pesquisados, somente Pseudomonas spp. foram identificadas em 13 (39,3%) isolados de AVL. Os resultados obtidos no presente estudo confirmam a presença de amebas de vida livre potencialmente patogênicas e carreadoras de bactérias patogênicas oportunistas que podem representar um risco à saúde humana. / Free-living amoebae (FLA) are protozoa widely distributed in natural and artificial environments. Some genus are opportunistic or pathogenic, with anfizoic feature : Acanthamoeba spp., Naegleria spp., Balamuthia spp., Sappinia spp., and recently Vermamoeba spp. AVL may serve as reservoirs for various pathogenic bacteria, since they feed by phagocytosis in the environment, some species of bacteria after internalized escape to the pathway of degradation surviving and multiplying within the amoebae. The aim of this study was to isolate and identify FLA and their associated bacteria present in water from cooling tower, whose temperature water varies between 25 to 30 °C (ideal for the development of different organisms). Amoebae were isolated in monoxenic cultivation with Escherichia coli inactivated by heat. Of the positive samples Polymerase Chain Reactions (PCR) were performed using specific primers for each genus. The PCR products were sequenced and the sequences were generated compared with partial sequences of each gene target deposited in GenBank. From the 36 samples, 33 (91.66%) were positive for the presence of FLA. Of these, 15 (45.4%) were positive for Acanthamoeba spp., 12 (36.3%) for Naegleria spp. and 6 (18.2 %) for Vermamoeba spp. Of the amoeba isolated, 13 (39.3%) were associated to bacteria wich belong to Pseudomonas genus (100%). Another bacteria investigated were absent. The results of this study confirm the presence of potentially pathogenic free-living amoebae as vehicles of opportunistic/pathogenic bacteria that can pose a risk to the human health.
36

Seleção de linhagens F5 de tomateiro em dois sistemas de cultivo sob temperaturas elevadas / Selecting lines F5 tomato in two cropping systems at elevated temperatures

SANTOS, Lucas da Silva 20 February 2012 (has links)
Submitted by (ana.araujo@ufrpe.br) on 2017-02-20T16:17:19Z No. of bitstreams: 1 Lucas da Silva Santos.pdf: 797064 bytes, checksum: c0db6a54d580614585740db051e28ad9 (MD5) / Made available in DSpace on 2017-02-20T16:17:19Z (GMT). No. of bitstreams: 1 Lucas da Silva Santos.pdf: 797064 bytes, checksum: c0db6a54d580614585740db051e28ad9 (MD5) Previous issue date: 2012-02-20 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Adverse environmental conditions, particularly high temperatures in tomato cause lower fertilization of the flowers, reducing fruit set and consequently the productivity. The ideal temperature for a better development and fruiting plant is 25 to 28ºC during the day and 15 to 18ºC overnight, outside these limits, the plant has trouble setting fruit. Thus, the aim of this work was to select F5 lines of tomato high temperature tolerance and genetic stability and adaptability in two culture environments. We evaluated 20 lines F5, and two controls Yoshimatsu and hybrid SE 1055 F1. The maximum mean temperature during the experiment inside the greenhouse and in the field were 37.46ºC and 32.55ºC, respectively, considered out of range to the ideal development of tomato, especially in the greenhouse, where the average maximum temperature was far above the ideal. Lines 08, 12 and 13 showed the highest percentage of fruit in a greenhouse, however in the field, there was no difference between lines. In field experiment, the cultivar Yoshimatsu and lines 06 and 08, showed average mass commercial fruit per plant more than 4.0 kg. Lines 06 and 08 showed high adaptability and stability and productivity for mass marketable fruits per plant, in the two environments, and for purposes of selection, the most suitable. / As condições ambientais adversas, principalmente temperaturas elevadas ao qual o tomateiro é submetido, provocam menor fertilização das flores, diminuindo o pegamento dos frutos e consequentemente a produtividade. A temperatura ideal para o melhor desenvolvimento e frutificação da planta é de 25 a 28ºC durante o dia e 15 a 18ºC durante a noite, fora desses limites, a planta passa a ter problemas na fixação de frutos. Desse modo, objetivou-se com esse trabalho selecionar linhagens F5 de tomateiro quanto à tolerância a altas temperaturas e a adaptabilidade e estabilidade genética em dois ambientes de cultivo. Foram avaliadas 20 linhagens F5, e como testemunhas a cultivar Yoshimatsu e o híbrido SE 1055 F1. Os valores médios da temperatura máxima durante o período do experimento no interior da casa de vegetação e no campo foram de 37,46ºC e 32,55ºC, respectivamente, considerados fora dos limites ideais ao desenvolvimento do tomateiro, principalmente em casa de vegetação, onde a média da temperatura máxima ficou muito acima da ideal. As linhagens 08, 12 e 13 apresentaram maior porcentagem de pegamento de frutos na casa de vegetação, já no campo, não houve diferença entre as linhagens. As linhagens 06 e 08 e a cultivar Yoshimatsu, no experimento de campo, apresentaram média de massa comercial de frutos por planta superior a 4,0 kg. As linhagens 06 e 08 apresentaram maior adaptabilidade e estabilidade e produtividade para massa de frutos comerciais por planta, aos dois ambientes, sendo, para efeito de seleção, as mais indicadas.
37

Estimativas de parâmetros genéticos em populações segregantes de amendoim

LUZ, Lucas Nunes da 20 February 2009 (has links)
Submitted by (ana.araujo@ufrpe.br) on 2017-02-20T16:33:34Z No. of bitstreams: 1 Lucas Nunes da Luz.pdf: 382023 bytes, checksum: 08d92e3154572bc09390dc2370ab2019 (MD5) / Made available in DSpace on 2017-02-20T16:33:34Z (GMT). No. of bitstreams: 1 Lucas Nunes da Luz.pdf: 382023 bytes, checksum: 08d92e3154572bc09390dc2370ab2019 (MD5) Previous issue date: 2009-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present work had for objective esteem the genetic parameters in hybrid populations of peanut for on characters the production, related to the peg and evaluate through the genotypic correlation and of the coefficient of path analysis contribution in the selection for production of pods per plant. One used F2 lines of a crossing between varieties BR 1 and advanced line CNPA 280 AM. The crossings had been carried through in house of vegetation of the UFRPE and gotten lines F 1 inbreeding. The F2 lines had been cultivated in field in the cities of Abreu e Lima and GoianaPE, in regimen of dry land, the period of May the Agost in 2008. The adoptedexperimental delineation was blocks to random with 3 blocks. The reproductive efficiency (EF1 and EF2), the total number of pegs (NGT), the number of pegs in first part of the plant (NGTI), the height of the main stem (AHP) and the number of pods (NVP) for plant had been evaluated. The data had been processed by applicatory the computational SAS assuming a mixing model. The estimates of the genetic parameters had been gotten by method RELM (Restricted Maximum Likelihood) and the individual genotypics values predicted by BLUP (Best Linear Unbiased Prediction). The environment variance was biggest the genotypic, in all the describers in the two studied environments. The magnitude of the heritability for all the describers was environments enters low and medium, indicating bigger perspective of selection in post generations. The magnitude of the heritability all the describers in the two studied environments showed enters low and medium, indicating bigger perspective of selection in post generations. The lines L.8 e L.11 showed biggest level of reproductive efficiency, more than hability for transform pegs in mature pods. The describers NGTI offers to greater possibility of selection for production of pods. / O presente trabalho teve por objetivo estimar os parâmetros genéticos em populações segregantes de amendoim para caracteres ligados a produção, associados ao ginóforo e avaliar via correlação genotípica e coeficiente de trilha os de maior contribuição na seleção para produção de vagens por planta. Foram utilizados progênies F2 de um cruzamento entre as variedades BR 1 e a linha avançada CNPA 280 AM, que possuem: alta capacidade produtiva e floração concentrada na base da planta com alta eficiência reprodutiva, respectivamente. Os cruzamentos foram realizados em casa de vegetação da UFRPE, sendo as progênies F 1 obtidas postas para autofecundar. As progênies F2 foram cultivadas em campo nos municípios de Abreu e Lima e GoianaPE, em regime de sequeiro, noperíodo de maio a agosto de 2008. O delineamento experimental adotado foi blocos ao acaso com 3 blocos. A colheita procedeu-se em média aos 90 dias após o plantio. Foram avaliadas a eficiência reprodutiva (EF1 e EF2), o número total de ginóforos (NGT), o número de ginóforos no terço inferior da planta (NGTI), a altura da haste principal (AHP) e o número de vagens por planta (NVP). Os dados foram processados pelo aplicativo computacional SAS assumindo um modelo misto. As estimativas dos parâmetros genéticos foram obtidas pelo método RELM (Restricted Maximum Likelihood) e os valores genotípicos individuais preditos pelo método BLUP (Best Linear Unbiased Prediction). A variância ambiental foi superior as demais para todos os descritores nos dois locais estudados. A magnitude da herdabilidade para todos os descritores situou-se entre baixa e mediana, indicando maior perspectiva de seleção em gerações posteriores. Os maiores valores genotípicos individuas foram obtidos para o descritor NGTI. A predição dos valores genéticos individuais obtidos BLUP auxilia melhor na seleção das linhagens deamendoim no inicio do melhoramento do que as estimativas de herdabilidade, para os descritores estudados. As linhagens L.8 e L.11, apresentaram os melhores níveis de eficiência reprodutiva EF1 e EF2, se mostrando mais aptas a transformar ginóforos em vagens maduras. Pela análise de trilha, observa-se que o descritor número de ginóforos no terço inferior da planta oferece maior possibilidade de seleção para produção de vagens.
38

Molecular characterization of Malaysian methicillin-resistant Staphylococcus aureus

Lim, Tien Tze January 2007 (has links)
Seventy-four methicillin-resistant Staphylococcus aureus (MRSA) from two Malaysian hospitals were characterised by both phenotypic and genotypic techniques. These isolates were collected over an 18 year time period in the years, 1982, 1989, 1994 and 2000. All of the Malaysian MRSA isolates were found to be multiresistant and resistant to at least five different antimicrobial agents. Over 30% of them were non-typable by the International Basic Set of bacteriophages. The majority of the typable isolates were susceptible to the group III phages, especially phage 85. The majority of the isolates carried one to six plasmids. Only two isolates were plasmid free. The plasmid profiles of these isolates, other than the 1982 isolates, were very similar to each other. Contour-clamped homogeneous electric field (CHEF) gel electrophoresis was used to examine the genetic relatedness of the isolates. Twenty-six CHEF patterns were found among the isolates. These CHEF patterns were closely related to each other. The predominant CHEF pattern A was found in the 1982, 1989 and 1994 isolates. The CHEF patterns of the year 2000 isolates were different to CHEF pattern A, but still closely related. All of the isolates were found to carry the Allotype III SCCmec and have coagulase-gene type 24. Multilocus sequence typing was preformed on the isolates with CHEF pattern A collected in different years. These isolates were found to have either sequence type 239 (ST239), or its single locus variant. The predominant Malaysian clone belongs to the pandemic clone ST239-MRSA-III that is pandemic in Asian countries. (Enright, 2003, Ko et al., 2005). / A 1.5 kb cryptic plasmid found in Malaysian isolates was indistinguishable from a cryptic plasmid found in an Australian isolate. A 3.0 kb cryptic plasmid found in Malaysian isolates was undistinguishable from a 3.0 kb plasmid found in Singaporean isolates. Class II multiresistance plasmids of 28, 30.5 and 35 kb were commonly found together in many Malaysian MRSA isolates. Both the 28 and 30.5 kb plasmids encode resistance to the heavy-metals and nucleic acid-binding (NAB) compounds. The 35 kb plasmid carries heavy-metal and NAB resistance but also encodes β-lactamase. Structurally these three plasmids are almost identical and probably have the same origin. The differences observed between these plasmids is probably due to excision or partial deletion of the β-lactamase transposon of the original plasmid. The 28 kb plasmid is identical to the 28 kb plasmid of Singaporean and some Australian isolates. A 20 kb plasmid in Indonesian isolates was found to be closely related to these three plasmids. A conjugative plasmid, pWBG707, conferring trimethoprim-resistance was found in Malaysian isolates. It did not carry either of the two staphylococcal trimethoprim-resistance genes, dfrA and dfrD. (Lyon and Skurray, 1987, Dale et al., 1995b) It either encodes a novel resistance gene or the recently discovered dfrG gene. (Sekiguchi et al., 2005) pWBG707 was also found to mobilise a small 3.0 kb kanamycin-resistance plasmid during conjugation. / The mecR1 and mecI genes regulating the transcription of the methicillin-resistance gene, mecA, were also examined in the isolates. The Malaysian isolate, WBG7422, with the predominant CHEF pattern A has a nonsense mutation in its mecI gene that disables it. However, its mecR1 gene is intact. The eastern Australia MRSA (EA MRSA), WBG525, has a CHEF pattern that is closely related to the Malaysian predominant CHEF pattern A and its mecI gene has a mutation identical to the Malaysian isolate. Unlike the Malaysian isolate however, its mecR1 gene has a 166 bp deletion. Both WBG7422 and WBG525 express Class III heterogeneous methicillin resistance. However, WBG525 has more highly resistant cell in its population than WBG7422. The loss of aminoglycoside resistance, together with c. 114 kb of chromosomal DNA, was observed in some Malaysian isolates. The deleted segment was found to carry the aacA-aphD gene that encodes a bifunctional aminoglycoside-modifying enzyme conferring resistance to many of the aminoglycosides. The Malaysian isolates were compared with MRSA from different countries. These MRSA included 18 epidemic MRSA (EMRSA) from the United Kingdom, 15 Australian nosocomial MRSA, five classical MRSA, 22 community-acquired MRSA (CMRSA) from Australia and New Zealand and 46 nosocomial MRSAs from eight Asian-Pacific countries and South Africa. These Asian-Pacific countries were Australia, PR China, Hong Kong, Indonesia, Japan, Philippines, Singapore and Taiwan. / The CHEF patterns of most of the Asian-Pacific and South African isolates were closely related to the Malaysian isolates. Isolates from Singapore, Indonesia and Philippines were found to have an identical CHEF pattern to the Malaysian CHEF patterns A5. The Asian-Pacific and South African isolates, including the Malaysian isolates, were found to be closely related to EMRSA-1, -4 and -7. These EMRSA belong to the ST239-MRSA-III clone and are coagulase-gene type 24. The isolates from Japan were the only Asian-Pacific isolates not related to the other Asian-Pacific isolates and EMRSAs. EMRSA-1 and EA MRSA have the same 166 bp deletion in their mecR1 gene. Both of these strains have closely related CHEF patterns, the same sequence type, coagulase-gene type and SCCmec. These results indicate that these two strains belongs to the same clone and confirms the international spread of this clone in the early 1980s. However, the Malaysian isolates have CHEF patterns that are more closely related to EMRSA-4 than to EMRSA-1. Similar to the Malaysian isolates EMRSA-4 has an intact mecR1 gene. The CMRSA isolates were not related to any of the nosocomial MRSA. They also have very diverse genetic backgrounds but carry less diverse SCCmec allotypes. Most of the CMRSA carry either Allotype IV or V SCCmec These results show that the spread of Malaysian MRSA is due to a single clonal expansion. Infection control measures would have to have been more efficient if this clone was to have been contained. The Malaysian epidemic clone is the Asian pandemic clone, ST239-MRSA-III. The Malaysian isolates and EMRSA-4 probably share the same ancestor. / The presence of the same MRSA strain in Malaysian hospitals and in the hospitals of neighbouring countries indicates that the inter-hospital spread of an epidemic MRSA has occurred. This observation also suggests that the infection control measures in Malaysian hospitals have not been totally effective. The ineffectiveness of infection control has left Malaysian hospitals vulnerable to the future importation of new pandemic clones and/or highly virulent or resistant clones.
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Biodiversidade de amebas de vida livre e bactérias associadas a amebas em reservatórios de água de torres de resfriamento / Biodiversity of free-living amoebae and bacteria associated with amobae in tanks water from cooling towers

Oliveira, Scheila da Silva Soares de January 2016 (has links)
Amebas de vida livre (AVL) são protozoários amplamente distribuídos na natureza e em ambientes artificiais. Alguns gêneros são oportunistas ou patogênicos, com característica anfizóica, são esses: Acanthamoeba spp., Naegleria spp., Balamuthia spp., Sappinia spp., e recentemente Vermamoeba spp. AVL podem servirem de reservatórios de várias bactérias patogênicas, uma vez que se alimentam dessas no ambiente por fagocitose, algumas espécies de bactérias após internalizadas escapam da via de degradação sobrevivem e multiplicam-se no interior das amebas. Face ao exposto, o presente trabalho objetivou isolar e identificar AVL e as bactérias associadas presentes em águas de torres de resfriamento, cuja temperatura da água varia entre 25 a 30°C (ideal para o desenvolvimento de diversos microrganismos). Amebas foram isoladas em cultivo monoxênico com Escherichia coli inativadas pelo calor. Das amostras positivas, foram realizadas Reações em Cadeia de Polimerase (PCR), utilizando oligonucleotídeos específicos para cada gênero. Os produtos das PCR foram sequenciados e as sequências geradas foram comparadas com sequências parciais de cada gene alvo depositadas no GenBank. Das 36 amostras, 33 (91,66%) foram positivas para presença de AVL, destas 15 (45,4%) foram positivas para Acanthamoeba spp., 12 (36,3%) para Naegleria spp., 6 (18,2%) para Vermamoeba spp. Dos endossimbiontes pesquisados, somente Pseudomonas spp. foram identificadas em 13 (39,3%) isolados de AVL. Os resultados obtidos no presente estudo confirmam a presença de amebas de vida livre potencialmente patogênicas e carreadoras de bactérias patogênicas oportunistas que podem representar um risco à saúde humana. / Free-living amoebae (FLA) are protozoa widely distributed in natural and artificial environments. Some genus are opportunistic or pathogenic, with anfizoic feature : Acanthamoeba spp., Naegleria spp., Balamuthia spp., Sappinia spp., and recently Vermamoeba spp. AVL may serve as reservoirs for various pathogenic bacteria, since they feed by phagocytosis in the environment, some species of bacteria after internalized escape to the pathway of degradation surviving and multiplying within the amoebae. The aim of this study was to isolate and identify FLA and their associated bacteria present in water from cooling tower, whose temperature water varies between 25 to 30 °C (ideal for the development of different organisms). Amoebae were isolated in monoxenic cultivation with Escherichia coli inactivated by heat. Of the positive samples Polymerase Chain Reactions (PCR) were performed using specific primers for each genus. The PCR products were sequenced and the sequences were generated compared with partial sequences of each gene target deposited in GenBank. From the 36 samples, 33 (91.66%) were positive for the presence of FLA. Of these, 15 (45.4%) were positive for Acanthamoeba spp., 12 (36.3%) for Naegleria spp. and 6 (18.2 %) for Vermamoeba spp. Of the amoeba isolated, 13 (39.3%) were associated to bacteria wich belong to Pseudomonas genus (100%). Another bacteria investigated were absent. The results of this study confirm the presence of potentially pathogenic free-living amoebae as vehicles of opportunistic/pathogenic bacteria that can pose a risk to the human health.
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Perfil genotípico do HIV-1 em crianças infectadas tratadas e não tratadas com antiretrovirais

Yamaguti, Elizabete Pires 26 May 2006 (has links)
Made available in DSpace on 2016-12-23T13:55:57Z (GMT). No. of bitstreams: 1 tese Bete atual 3 maio 2006.pdf: 1008546 bytes, checksum: 47a15ef84c9d3ffd6d4e5ae6595331a5 (MD5) Previous issue date: 2006-05-26 / Embora os protocolos de prevenção da transmissão vertical do HIV-1 atualmente preconizados venham contribuindo para a redução da infecção na população pediátrica nos países desenvolvidos, um grande número de crianças continua sendo infectado pelo HIV em países em desenvolvimento. Dados sobre a infecção nesta população ainda são escassos. Neste trabalho, realizamos um levantamento do perfil genotípico do HIV em uma coorte de crianças infectadas pelo HIV-1 no Setor de Infectologia/AIDS Pediátrico do Centro de Referência do Hospital Infantil Nossa Senhora da Glória - Vitória / ES Os dados aqui apresentados demonstram que a prevalência e o nível de mutações de resistência às drogas foram mais evidentes no grupo de pacientes recebendo terapia com ARVs quando comparados ao grupo de pacientes virgem de tratamento, corroborando com o conceito de ação da pressão seletiva na emergência de cepas virais resistentes. Mutações de resistência primária aos ARVs não foram encontradas na grande maioria das crianças não tratadas (Grupo A), sustentando a hipótese que a transmissão vertical ocorreu a partir de mães que não tinham consciência do seu status sorológico e conseqüentemente não faziam uso de antiretrovirais. Neste grupo foi encontrado uma maior prevalência de mutações acessórias não conferindo resistência aos ARVs. A supressão máxima da replicação viral continua ser a principal meta a ser atingida pela terapia visando prevenir a emergência de cepas resistentes. Infelizmente, em 20-50% dos pacientes que iniciam HAART essa supressão viral sustentada não é atingida e podendo ser ainda maior em pacientes em esquemas de tratamentos seqüenciais. Embora, muitos fatores possam ser associados com falha virológica, incluindo baixa aderência, farmacocinética dos ARVs e regimes de tratamento sub-ótimos, a emergência de variantes virais resistentes aos ARVs tem sido a principal causa de falha de tratamento. O desenvolvimento de resistência aos ARVs tem um maior impacto no tratamento destas crianças por poder levar ao aparecimento de resistência cruzada, limitando opções futuras. A grande maioria das crianças no Grupo B já estavam em tratamento com ARVs há mais de 7 anos, sendo que alguns já haviam passado pela fase de monoterapia com AZT, depois terapia dupla e hoje se encontram no seu 2º, 3º e até mesmo 4º esquema de HAART. Estes fatos podem explicar a dificuldade de supressão da replicação viral e a conseqüente falha no tratamento encontrada nesta população. Os dados aqui apresentados enfatizam a importância de identificarmos o momento apropriado para o início da terapia com ARVs, bem como a escolha mais adequada da combinação de ARVs que leve à supressão da replicação viral de forma efetiva, sem deixarmos de considerar a importância da adesão ao esquema terapêutico por parte dos responsáveis legais por estas crianças. / Although existing protocols to prevent HIV-1 vertical transmission have contributed to reduce infection within the pediatric population in developed countries, a significant large number of children is still been infected vertically in undeveloped countries. Data regarding the latter population is still scarce. The HIV genotypic profile of a cohort of HIV-1 infected children attending to the Infectious Disease/Pediatric AIDS Ward of the Children s Hospital Nossa Senhora da Glória - Vitória / ES was evaluated in the present work. Our data demonstrated that both the prevalence and the level of genotypic resistance mutations were more evident among patients receiving HAART therapy (Group B) when compared to treatment naive patients (Group A), which supports the previous data showing the key role of antiretroviral (ARV) drugs selective pressure on the emergence of resistant virus isolates. Antiretroviral primary resistance mutations were not found in the great majority of treatment naive children, supporting the hypothesis that vertical transmission occurred from mother that didn t know their serological status and were not under treatment with ARV, the highest prevalence of viral polymorphism non-related to ARV resistance was found in this group. The main goal of ARV therapy is to achieve total suppression of viral replication, in order to prevent the emergence of ARV resistant strain. Unfortunately, in 20-50% of patients initiating HAART this total suppression is not achieved, this failure rate may be even higher among patients in sequential treatment regimens. Although several factors could be associated with treatment failure, such as non-compliance, ARV pharmacokinetics and inadequate treatment regimens, the emergence of ARV resistant viral mutants is still the main responsible for treatment failure. The development of ARV resistance has a greater impact among pediatric patients due to the fact that it may lead to cross-resistance, which may limit the use of other ARV later on. Most of the children in Group B were under treatment with ARV for more than 7 years, including some that received AZT monotherapy, than double therapy and today are in their 2nd, 3rd or even 4th HAART regimen. This fact may explain the difficulty in achieving total suppression of viral replication and consequently the high frequency of treatment failure found among patients in this group. Data presented here emphasize the importance of the correct timing for beginning ARV therapy, as well as the correct choice of ARV to achieve viral replication suppression efficiently, without forgetting the importance of patient compliance to the therapeutic regimen enforced by the legal guardians of these children.

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