El objetivo de esta Tesis Doctoral fue realizar la caracterización química y tóxica así como analizar la mutagenicidad y antimutagenicidad del extracto acuoso de Baccharis articulata (Lam.) Persoon (EAB). B. articulata, conocida como “Carqueja”, es una hierba silvestre utilizada muy frecuentemente en la medicina folclórica popular en Argentina y Sudamérica. La infusión de carqueja es ampliamente consumida para el tratamiento de afecciones gastrointestinales por su capacidad antiespasmódica y colagoga, entre otras. Mediante caracterización química por cromatografía líquida de fase inversa (RF-HPLC) se determinaron los compuestos fenólicos presentes en el EAB. Asimismo, se analizó la actividad antioxidante del EAB, por determinación de la concentración eficiente cincuenta (CE50) mediante la técnica de DPPH* (2, 2-fenil1-picril hidracilo) y se determinaron los porcentajes de inhibición del EAB frente al radical DPPH*. El análisis químico del EAB reveló que el polifenol mayoritario fue el ácido clorogénico. El contenido de ácido clorogénico en el EAB fué 2,05±0,11 mg/ml y su actividad antioxidante presentó un valor de CE50 de 101,86 µg/ml. Los estudios de toxicidad, mutagenicidad y capacidad antimutagénica se realizaron mediante el Ensayo de Ames empleando las cepas testigo Salmonella typhimurium TA98 (mutante de corrimiento de marco de lectura) y TA100 (mutante de sustitución de bases). Los ensayos de toxicidad se llevaron a cabo por determinación de las unidades formadoras de colonias co-incubando el EAB con las cepas testigo para evaluar concentraciones no tóxicas. Los ensayos de mutagenicidad y antimutagenicidad se realizaron con diferentes concentraciones del EAB (1,0 y 10,0 mg/placa) las cuales se incubaron con diferentes concentraciones de mutágenos diagnóstico: 2-nitrofluoreno (2-NF), azida sódica (AZS), y 2-aminofluoreno (2-AF). Se implementó el método clásico de incorporación en placa y su modificación de pre-incubación. Para la evaluación de la antimutagenicidad se tomaron como parámetros los porcentajes de inhibición (%I) ejercidos por el EAB frente a la mutagenicidad inducida por los mutágenos diagnóstico (correspondiente al 100% de mutagenicidad). Los resultados encontrados indicaron al aplicar el Ensayo de Ames, que el EAB no resultó tóxico ni mutagénico en las concentraciones ensayadas (1,0 y 10,0 mg/placa) y en las condiciones de diseño experimental propuestos. El EAB presentó en el Ensayo de Ames aplicado un %I de 100% frente al mutágeno 2-AF al implementar el método de pre-incubación y con la cepa TA100, independiente de las concentraciones ensayadas (1,0 y 10,0 mg/placa). Los valores máximos de inhibición del EAB ejercidos en la cepa TA98 frente al 2-NF se obtuvieron con 10,0 mg/placa de EAB y el Ensayo de Ames, con el método de pre-incubación, siendo el %I de 91,0%. Frente a la AZS, la máxima inhibición se obtuvo, en el Ensayo de Ames, con el método de pre-incubación con un rango de %I de 40,0-41,0% para 1,0 y 10,0 mg/placa, respectivamente. Asimismo, se evaluó la capacidad antioxidante, tóxica, mutagénica y antimutagénica del ácido clorogénico utilizando la misma metodología implementada para el EAB (DPPH* y el Ensayo de Ames). Los resultados mostraron que la capacidad antioxidante del ácido clorogénico resultó ser mayor que la del EAB con una CE50= 0,269 µg/ml. El ácido clorogénico mostró ser no tóxico y no mutagénico en el Ensayo de Ames, en las concentraciones ensayadas (0,05 y 0,50 mg/placa). Los estudios de antimutagenicidad del ácido clorogénico mostraron que los %I máximos frente a 2-AF se obtuvieron con la cepa TA98 (%I de 75,5) y con la cepa TA100 (%I de 84,0), ensayando 0,50 mg/placa de ácido clorogénico mediante el método de pre-incubación. En base a estos resultados, se concluyó que el EAB y el ácido clorogénico poseen capacidad antioxidante y antimutagénica en los sistemas y condiciones experimentales aplicadas. La comparación de la capacidad antimutagénica entre el EAB y el ácido clorogénico indicó que fue necesaria una concentración cinco veces mayor de ácido clorogénico contenido en la muestra de EAB para alcanzar una actividad antimutagénica similar a la observada en el EAB. Se concluyó que la capacidad antimutagénica del EAB ocurría a través de un mecanismo antioxidante, influenciado por la presencia del ácido clorogénico y otros compuestos presentes en el mismo. En base a los datos obtenidos y la bibliografía existente se propone que los efectos antimutagénicos ejercidos por el EAB frente a los mutágenos ensayados respondería a un mecanismo llamado “desmutágeno”, donde la inhibición ejercida por el extracto posiblemente ocurra previamente a que los agentes mutagénicos produzcan un daño total o parcial sobre el ADN. Futuros estudios sobre los mecanismos moleculares implicados en el efecto antimutagénico ejercido por el EAB frente a diferentes mutágenos resultan necesarios y merecen ser estudiados en profundidad para dilucidar el posible mecanismo propuesto en la presente Tesis Doctoral a partir de observaciones realizadas en cepas bacterianas aplicando el Ensayo de Ames.

Causes and consequences of woody encroachment into grass dominated systems have been widely studied, however functional mechanisms which promote encroachment are largely unknown. Many expansive woody species are shrubs with rhizobial or actinorhizal N-fixing symbiotic associations. Morella cerifera L. (Myricaceae) is an actinorhizal N-fixing shrub which rapidly expands into grasslands on the barrier islands off the coast of Virginia, USA. The objective of this research was to determine physiological drivers of woody encroachment resulting in increased woody cover of M. cerifera on Southeastern, US barrier islands. Variations in physiology and resource use efficiencies (RUE) of M. cerifera and co-occurring shrubs were determined, and edaphic characteristics beneath shrub thicket canopies and in open areas were quantified as indications of resource availability. Analysis of dune vegetation and soils showed severe freshwater limitation and reduced plant height of dune forbs suggesting dunes represent an upper elevational boundary for M. cerifera distribution. Soil N availability was higher beneath shrubs compared to open areas, and both physiology and isotope effects showed facilitation of the non-fixing shrub, Baccharis halimifolia, by M. cerifera which may lead to increased rates of woody encroachment as B. halimifolia colonizes expanding thicket edges. Morella cerifera and other N-fixers had higher %refixation within stems which resulted in higher carbon use efficiency (CUE) and water use efficiency of N-fixing shrubs compared to non-fixers. Results of an N-fertilization experiment suggest B. halimifolia has higher dependence on and demand for soil nutrients compared to M. cerifera. Morella cerifera showed no signs of resource deficiency or reduced physiological capacity even at 0 ppm total Nsoil. Morella cerifera transitioned from utilizing solely fixation derived N to soil N as N concentrations increased providing another mechanism leading to increased CUE and, indirectly, overall RUE. In summary greater RUE, lower resource demand, and greater resource availability for M. cerifera compared to co-occurring shrubs may result from symbiotic root associations with bacteria and fungi. While expansion of M. cerifera thickets is limited to lower elevational interdunal depressions, expansion may continue and result in increased rates of woody encroachment through facilitation of co-occurring shrubs.

It is important to understand mechanisms that facilitate expansion of two common shrubs, Morella cerifera and Baccharis halimifolia in coastal environments. The purpose of my study was to investigate the physiological and structural changes that occur as leaves age. Photosynthesis, incident light, chlorophyll, and leaf C:N ratios were quantified for young, intermediate, and old leaves (distal, central and proximal leaves, respectively). Leaf structural differences were also compared. Leaves did not change morphologically with age. Light decreased with leaf age and during winter months. Photosynthesis showed no seasonal or age related patterns. Chlorophyll increased initially and then declined with age due to self shading. Nitrogen content was highest during spring. Seasonality and leaf age had unique effects on the two study species. Understanding senescence adaptations of these two shrubs can help explain their abundance in coastal ecosystems.

Listeria monocytogenes é um bastonete Gram-positivo, anaeróbio facultativo, psicrotrófico, patogênico a humanos e transmitido por alimentos. É causador da listeriose, doença severa que acomete grupos de risco específicos, tais como idosos, imunocomprometidos, gestantes, crianças e recém-nascidos. Neste trabalho foi investigada a expressão diferencial de L. monocytogenes na presença de óleo essencial extraído de Baccharis psiadioides, planta da família Asteraceae popularmente chamada de “alecrim-do-campo”, “vassoura” ou “erva formiga”, utilizada pela população como planta medicinal. Além disso, os genomas de dois diferentes sorotipos de L. monocytogenes, frequentemente associados a surtos de listeriose, foram sequenciados através de plataforma MiSeq Illumina, sequências estas depositadas no GenBank, e comparados com genomas de referência. Anteriormente à execução das análises genômica e transcriptômica, foi determinada a composição do óleo essencial extraído de B. psiadioides utilizado nos experimentos, através de cromatografia gasosa com espectrômetro de massa (GC – MS), a qual demonstrou uma maior quantidade de β-pineno na fração composta majoritariamente por monoterpenos, composto este frequentemente encontrado em plantas medicinais aromáticas e apontado como um dos responsáveis pelo potencial antimicrobiano das mesmas. Os demais resultados obtidos no presente trabalho indicam que o óleo essencial testado apresenta potencial ação bacteriostática na concentração estudada, sendo que genes relacionados à virulência do microrganismo foram menos transcritos na sua presença, ao contrário do que foi observado para genes de resposta ao estresse, que apresentaram maiores níveis de transcrição nesta condição. A comparação genômica entre os genomas bacterianos sequenciados neste trabalho e as cepas referência sugere um maior número de proteínas expressas em L. monocytogenes do sorotipo 4b relacionadas à defesa e metabolismo do microrganismo, indicando mecanismos que podem estar envolvidos com a capacidade deste sorotipo estar mais envolvido nos casos humanos de listeriose. / LLiisstteerriiaa mmoonnooccyyttooggeenneess is a Gram-positive rod-shaped microorganism, facultative anaerobic, psychrotrophic, pathogenic to humans and transmitted by food. It causes listeriosis, a severe disease that affects specific risk groups such as elderly, immunocompromised, pregnant women, children and newborns. In this study, differential expression of LL.. mmoonnooccyyttooggeenneess in the presence of essential oil extracted from BBaacccchhaarriiss ppssiiaaddiiooiiddeess, a plant from AAsstteerraacceeaaee family popularly named as "alecrim-do-campo", "vassoura" or "erva formiga" used by population as a medicinal plant, was investigated. In addition, the genomes of two different LL.. mmoonnooccyyttooggeenneess serotypes, often associated with listeriosis outbreaks, were sequenced through the MiSeq Illumina platform. These sequences were deposited in GenBank and compared with reference genomes. Prior to the execution of genomic and transcriptomic analyzes, composition of the essential oil extracted from BB.. ppssiiaaddiiooiiddeess used in the experiments was determined by gas chromatography with mass spectrometer (GC-MS), which demonstrated a higher amount of β-pinene in the fraction composed mainly by monoterpenes. This compound is often found in aromatic medicinal plants and also pointed as one of those responsible for their antimicrobial potential. The other results obtained in the present study indicate that the essential oil tested has a potential bacteriostatic activity at the concentration studied, and genes related to the virulence of the microorganism were less transcribed in its presence, contrary to what was observed for stress response genes, which presented higher transcription levels on that condition. Comparative genomics between the bacterial genomes sequenced in this work and the reference strains suggests a higher number of proteins expressed in LL.. mmoonnooccyyttooggeenneess serotype 4b related to the defense and metabolism of the microorganism, indicating mechanisms that may be involved with the greater ability of this serotype to cause human listeriosis.

Resumo: O presente estudo teve como objetivo avaliar o potencial de atividade antimicrobiana in vitro dos extratos de algumas plantas endêmicas do Cerrado, tais como Baccharis dracunculifolia, Cochlospermum regium, Croton antisyphiliticus, Eugenia dysenterica e Lippia sidoides, frente a estirpes de Staphylococcus aureus isoladas de leite de vacas com mastite e de fontes de contaminação envolvidas na epidemiologia da mastite bovina. Os extratos foram preparados a partir das partes aéreas e sistema radicular das plantas, utilizando os solventes metanol, hexano e clorofórmio, por processo de maceração estática. Para avaliação da atividade antimicrobiana foram aplicadas as técnicas de difusão em disco, microdiluição em caldo para determinação da Concentração Inibitória Mínima (CIM) e Concentração Bactericida Mínima (MBC). Dentre os extratos que apresentaram atividade bacteriostática, o extrato hexânico de Baccharis dracunculifolia destacou-se com CIM de 10 mg/mL sobre 45% das estirpes. Enquanto o extrato clorofórmico de Croton antisyphiliticus, com atividade bactericida, inibiu a multiplicação de 100% das estirpes de Staphylococcus aureus, com CIM variando entre 1,03mg/mL e 4,15 mg/mL. O estudo demonstra ainda, que tais extratos vegetais apresentaram resultados superiores aos obtidos com a gentamicina, princípio ativo muito utilizado no combate à mastite bovina, reforçando a importância das plantas medicinais como recurso terapêutico. / Abstract: The purpose of this study was to assess the potential of in vitro antimicrobial activity of the extracts of certain endemic plants in the Brazilian Cerrado, such as Baccharis dracunculifolia, Cochlospermum regium, Croton antisyphiliticus, Eugenia dysenterica and Lippia sidoides, against strains of Staphylococcus aureus isolated from the milk of cows with mastitis and sources of contamination involved in the epidemiology of bovine mastitis. The extracts were prepared by using aerial parts and radicular systems of the plants, using methanol, hexane and chloroform as solvents, extracted with static maceration. Techniques of disc diffusion, broth microdillution for the determination of Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were used for the assessment of antimicrobial activity. Among the extracts with bacteriostatic activity, the hexanic extract of Baccharis dracunculifolia had a 10 mg/mL MIC against 45% of the strains, whereas the chloroformic extract of Croton antisyphiliticus, with bactericidal activity, inhibited the multiplication of 100% of the Staphylococcus aureus strains, whose MIC varied between 1.03mg/mL and 4.15 mg/mL. The study also demonstrated that the results of these plant extracts are superior to the results obtained with gentamicin, an active principle commonly used against bovine mastitis, reinforcing the importance of medicinal plants as a therapeutic resource. / Orientador:Luiz Augusto do Amaral / Coorientadora: Ana Maria Soares Pereira / Banca: Bianca Waléria Bertoni / Banca: Oswaldo Durival Rossi Junior / Mestre

Bachelor project. / Haves kun i elektronisk udg.

Invasive plants have a significant detrimental effect on ecosystems globally, with impacts estimated at millions of dollars per invasive species each year. Biological control has long been used as a management tool for invasive plants, as it is considered a long–term cost–effective control strategy. Surprisingly, the impact of biological agents is rarely quantified. Any form of impact evaluation is generally conducted soon after agent release and establishment; with few studies examining the impact of the agents on the population dynamics of the invader, particularly once the agents have been established for a long time. The aim of the research in my thesis is to evaluate the biological control program of groundsel bush (Baccharis halimifolia L. Asteraceae) in Australia. The groundsel bush biological control agents were released up to 40 years ago and no quantitative assessment of agent impact has ever been conducted, despite the fact that the program has cost about $9.6 million. More specifically, the overall aim of this thesis is to investigate the impact of the released biological control agents on individual plants and populations of groundsel bush. In addition, my thesis aims to examine the impacts of climate as a potential confounding factor of the biological control program. My thesis provides a unique example of biological control evaluation by using a combination of observational damage studies, insect exclusion experiments, and statistical, population and climate modelling to assess, a posteriori, the effectiveness of biological control. This is the first time a long term biological control program has ever been evaluated. To assess the efficacy of the agents, I conducted a large field survey to examine whether the agents were distributed throughout the entire range of groundsel bush and if any biotic or abiotic factors influenced their effectiveness. In addition to this, I assessed the effect of the agents on the growth, survival and fecundity of individual plants under field conditions, and subsequently population growth rate. To do this, I used statistical models of observed effects of biological control agent damage and insect exclusion experiments on plant growth and fecundity to parameterise matrix population models. My results indicate that the groundsel bush biological control agents may be patchy in their effectiveness due to factors such as rainfall and plant size. At their current rate of damage, the groundsel bush biological control agents do not reduce plant growth or fecundity significantly. However, simulation models demonstrated that the agents have the potential to reduce individual plant and population growth when damage is at high levels. A reduction in an invader’s population growth rate, following the introduction of biological control agents, does not necessarily signify that the agents were responsible for the reduction. Factors such as land clearing, chemical and mechanical control, ecosystem health and climate may reduce populations of invasive plant species. With this in mind, I developed a series of climate models to examine how the favourability for growth of groundsel bush may change under different climate scenarios. The climate simulations demonstrated that the distribution and abundance of groundsel bush populations may have contracted in the past 50 years (post–biological control agent release) due to changing rainfall and temperature patterns. The results of the research in my thesis clearly show the need for thorough biological control evaluations, and for detailed data to be collected on the target plant’s demography and population sizes pre- and post-agent release. At a minimum, this should enable biological control practitioners to determine some level of agent impact and demonstrate support for further agent releases or integrative management strategies if necessary. Groundsel bush is a significant invader in Europe where biological control has not yet been carried out. Lessons from the evaluation of the Australian biological control program could be applied to new biological control programs elsewhere such as Europe. Overall, my research findings contribute to a better understanding of how to best evaluate a post-release biological control program, using groundsel bush as a case study. This is the first study to demonstrate an effective set of strategies and quantitative tools to evaluate a biological control program, which can be similarly applied to any biological control program and contributes significantly to an area of biological control which has only recently received significant attention.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-03-24T17:35:42Z No. of bitstreams: 1 texto compelto.pdf: 576732 bytes, checksum: 71f65814b643bd9956f27054a48ca690 (MD5) / Made available in DSpace on 2017-03-24T17:35:42Z (GMT). No. of bitstreams: 1 texto compelto.pdf: 576732 bytes, checksum: 71f65814b643bd9956f27054a48ca690 (MD5) Previous issue date: 2016-08-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os plásticos derivados de petróleo representam um grande problema ambiental, devido à sua dificuldade de biodegradabilidade. Uma alternativa aos polímeros sintéticos é o uso de biopolímeros biodegradáveis, que são de fontes naturais, renováveis e de baixo custo. Os biopolímeros ainda têm seu uso limitado, devido às baixas propriedades mecânicas, térmicas e de barreira. O uso dos nanocompósitos pode melhorar as propriedades dos filmes biodegradáveis. Atualmente, há um grande interesse pelos consumidores por alimentos mais saudáveis, seguros e livres de conservantes sintéticos. As nanoemulsões de óleos essenciais vêm conferindo maiores propriedades antimicrobianas aos óleos essenciais, sendo utilizadas para a produção de embalagens ativas, com o objetivo de estender a vida de prateleira e inibir a multiplicação ou eliminar micro-organismos patogênicos e deteriorantes nos alimentos. Neste trabalho, foi desenvolvida uma embalagem ativa de hidroxipropilmetilcelulose, nanoemulsão de óleo essencial de carqueja (OE) e argila laponita (LAP). Na primeira etapa, foi produzida a nanoemulsão de óleo essencial de carqueja e caracterizada quanto à sua estabilidade físico-química. Avaliou-se o tamanho e a estabilidade da nanoemulsão durante sete dias de armazenamento, através das análises macroscópica, estresse térmico, diâmetro médio da gotícula, potencial zeta, índice de polidispersão e pH. A nanoemulsão apresentou-se estável sem a ocorrência de separação de fases, ou processos de instabilidade durante os sete dias de armazenamento. Na segunda etapa, avaliou-se a atividade antibacteriana do óleo essencial de carqueja sobre Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 15442) e Escherichia coli (ATCC 11229), determinando sua concentração mínima inibitória. Posteriormente, os filmes foram desenvolvidos e avaliados por meio de análise da atividade antimicrobiana in vitro, espessura, propriedades mecânicas, microscopia eletrônica de varredura (MEV), perfilometria óptica, taxa de permeabilidade ao vapor d’água (TPVA), e análise termogravimétrica (TGA). O óleo essencial apresentou atividade antibacteriana sobre S. aureus e P. aeruginosa, com concentração mínima inibitória de 1% (m/v). Quando avaliada a atividade antimicrobiana in vitro dos filmes, observou-se halo de inibição apenas para Gram-positiva (S. aureus). A espessura dos filmes não foi influenciada pela adição de LAP e OE. Quanto às propriedades mecânicas dos filmes, a resistência à tração e módulo de elasticidade foram influenciados apenas pela adição de OE. Já o alongamento na ruptura não foi afetado pela adição de OE e LAP. As análises de microscopia eletrônica de varredura e perfilometria óptica revelaram a formação de gotículas de óleo essencial, fissuras e poros na superfície dos filmes. Os valores de TPVA diminuíram quando a concentração de OE e LAP foi aumentada. O OE e LAP não influenciaram na estabilidade térmica dos filmes. Resultados sugerem que o filme de hidroxipropilmetilcelulose incorporado com nanoemulsão de óleo essencial de carqueja e argila laponita pode ser utilizado como embalagem ativa para aumentar a segurança e vida de prateleira dos alimentos. / Petroleum-based plastics are a major environmental problem because of their difficult degradability. An alternative to synthetic polymers is the use of biodegradable biopolymers, which are from natural sources, renewable and low cost. Biopolymers still have limited use due to the low mechanical, thermal and barrier properties. The use of nanocomposites can improve the properties of biodegradable films. Currently, there is a big interest by consumers for healthy foods, safe and free of synthetic additives. Nanoemulsions of essential oils provide major antimicrobial properties to essential oils, being used for the production of active packaging, aiming to extend the shelf life and inhibit the multiplication or eliminate pathogenic and spoilage microorganisms in food. In this work an active packaging was developed incorporated with nanoemulsion of carqueja essential oil (OE) and laponite clay (LAP). In the first stage, the nanoemulsions of carqueja essential oil were characterized as to their physical and chemical stability. The size and stability of the nanoemulsion were evaluated during seven days of storage through macroscopic analysis, thermal stress, average droplet diameter, zeta potential, polydispersity index and pH. The nanoemulsion was stable without the occurrence of phase separation, or instability processes during the seven days of storage. In the second stage, the antibacterial activity of carqueja essential oil on Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 15442) and Escherichia coli (ATCC 11229) was evaluated, determining its minimum inhibitory concentration. The films were developed and characterized by in vitro antimicrobial activity, thickness, mechanical properties, scanning electron microscopy (SEM), optical profilometry, water transmission rate (WVTR) and thermal gravimetric analysis (TGA). The carqueja essential oil showed antibacterial activity of against S. aureus and P. aeruginosa with minimal inhibitory concentration of 1% (w/v). When evaluated in vitro antimicrobial activity of the films was observed zones of inhibition only for Gram- positive (S. aureus). The thickness of the films was not influenced by the addition of LAP and OE. The mechanical properties were influenced by addition of OE. The SEM analysis and optical profilometry revealed the formation of essential oil droplets, fissures and pores on the surface of the films. The WVTR values decreased when increased the concentration of OE and LAP. The OE and LAP did not influence the thermal stability of the films. Results suggest that the hydroxypropyl methylcellulose film incorporated with nanoemulsions carqueja essential oil and laponite clay can be used as active packaging to increase the safety and shelf life of food.

Em comunidades vegetais podem existir diversos tipos de interações entre os indivíduos presentes, independente destes serem da mesma espécie (intraespecíficas) ou de espécies diferentes (interespecíficas). Em campo nativo caracterizado por efeitos de abandono, fortes modificações da estrutura da vegetação e reduções na diversidade têm sido observadas, atribuídos, entre outros fatores, à entrada de espécies arbustivas. Através de dados ecofisiológicos dos indivíduos participantes no processo, como taxa fotossintética, condutância estomática e transpiração foliar, é possível determinar se existe alguma interação entre as espécies presentes, Baccharis dracunculifolia, Baccharis trimera e Andropogon lateralis, se esta é benéfica, o que poderia caracterizar um processo de facilitação, se estas espécies estão competindo por recursos, ou até mesmo a ocorrência de neutralismo entre elas. Além disso, a caracterização da vegetação campestre em situações com ou sem arbustos pode contribuir para a avaliação do efeito dos arbustos. Para a realização desse estudo foram alocadas 15 parcelas com a presença da espécie arbustiva B. dracunculifolia e 15 parcelas, pareadas às primeiras, onde tal espécie não se encontra, totalizando 30 parcelas. Verificaram-se parâmetros fisiológicos, como taxas de fotossíntese e transpiração, a condutância estomática e a eficiência do uso da água das espécies selecionadas baseado na sua representatividade no ambiente de estudo, B. trimera e A. lateralis, bem como a estrutura, composição e diversidade da vegetação. Também foi realizado um censo da própria população de B. dracunculifolia. A fim de caracterizar as interações entre a espécie arbustiva e as espécies em sua sub-copa foram comparadas as médias dos parâmetros fisiológicos bem como parâmetros (diversidade, composição, riqueza) da comunidade vegetal em parcelas com ou sem arbustos por meio de análise de variância. Os resultados mostraram que B. dracunculifolia exerce certa competição para as duas espécies-alvo, mas não causa mudanças muito fortes na estrutura da vegetação. Como também foi observado que a população de B. dracunculifolia não esta conseguindo se regenerar num campo abandonado, pode ser concluído que a espécie, apesar da modificação forte da fisionomia vegetal, tem pouco impacto na dinâmica sucessional de um campo abandonado. / In plant communities, several types of interactions between individuals can occur, regardless of these being of the same species (intraspecific) or of different species (interspecific). In a grassland areas characterized by natural effects of abandonment, strong changes in vegetation structure and reduction in diversity have been observed, attributed, among other factors, to encroachment by a shrub species. Through ecophysiological data of individuals participating in the process, such as photosynthetic rate, stomatal conductance and leaf transpiration, it is possible to determine whether there is any interaction between the shrub species, Baccharis dracunculifolia, and two species growing under its canopy, Baccharis trimera and Andropogon lateralis, and, if so, if this it is beneficial, which could characterize facilitation of a process, if these species are competing for resources, or even neutrality between them. Furthermore, the characterization of the grassland community in situations with or without shrub can contribute to evaluate the effect of the latter. To conduct this study, 15 plots with the presence of shrub species B. dracunculifolia and 15 plots, paired with the first, where that species is not found were allocated in an abandonend grassland, totaling 30 plots. Physiological parameters (rates of photosynthesis and transpiration and stomatal conductance) of the two species selected based on their high abundance in the environment were studied, as well as the structure, composition and diversity of vegetation. Also, a census of the population of B. dracunculifolia itself was conducted. In order to characterize the interactions between the shrub species and the species in growing in its subcanopy the mean physiological parameters as well as parameters (diversity, composition, richness) of the plant community in plots with or without shrubs were compared by analysis of variance (ANOVA). The results showed that B. dracunculifolia exerts some competition between species, but does not cause strong changes in vegetation structure. As also could be noted that B. dracunculifolia is not regenerating in the abandoned grassland, it can be concluded that the species, despite the strong modification of vegetation physionomy, has little impact on the successional dynamics of abandoned grassland.

Listeria monocytogenes é um bastonete Gram-positivo, anaeróbio facultativo, psicrotrófico, patogênico a humanos e transmitido por alimentos. É causador da listeriose, doença severa que acomete grupos de risco específicos, tais como idosos, imunocomprometidos, gestantes, crianças e recém-nascidos. Neste trabalho foi investigada a expressão diferencial de L. monocytogenes na presença de óleo essencial extraído de Baccharis psiadioides, planta da família Asteraceae popularmente chamada de “alecrim-do-campo”, “vassoura” ou “erva formiga”, utilizada pela população como planta medicinal. Além disso, os genomas de dois diferentes sorotipos de L. monocytogenes, frequentemente associados a surtos de listeriose, foram sequenciados através de plataforma MiSeq Illumina, sequências estas depositadas no GenBank, e comparados com genomas de referência. Anteriormente à execução das análises genômica e transcriptômica, foi determinada a composição do óleo essencial extraído de B. psiadioides utilizado nos experimentos, através de cromatografia gasosa com espectrômetro de massa (GC – MS), a qual demonstrou uma maior quantidade de β-pineno na fração composta majoritariamente por monoterpenos, composto este frequentemente encontrado em plantas medicinais aromáticas e apontado como um dos responsáveis pelo potencial antimicrobiano das mesmas. Os demais resultados obtidos no presente trabalho indicam que o óleo essencial testado apresenta potencial ação bacteriostática na concentração estudada, sendo que genes relacionados à virulência do microrganismo foram menos transcritos na sua presença, ao contrário do que foi observado para genes de resposta ao estresse, que apresentaram maiores níveis de transcrição nesta condição. A comparação genômica entre os genomas bacterianos sequenciados neste trabalho e as cepas referência sugere um maior número de proteínas expressas em L. monocytogenes do sorotipo 4b relacionadas à defesa e metabolismo do microrganismo, indicando mecanismos que podem estar envolvidos com a capacidade deste sorotipo estar mais envolvido nos casos humanos de listeriose. / LLiisstteerriiaa mmoonnooccyyttooggeenneess is a Gram-positive rod-shaped microorganism, facultative anaerobic, psychrotrophic, pathogenic to humans and transmitted by food. It causes listeriosis, a severe disease that affects specific risk groups such as elderly, immunocompromised, pregnant women, children and newborns. In this study, differential expression of LL.. mmoonnooccyyttooggeenneess in the presence of essential oil extracted from BBaacccchhaarriiss ppssiiaaddiiooiiddeess, a plant from AAsstteerraacceeaaee family popularly named as "alecrim-do-campo", "vassoura" or "erva formiga" used by population as a medicinal plant, was investigated. In addition, the genomes of two different LL.. mmoonnooccyyttooggeenneess serotypes, often associated with listeriosis outbreaks, were sequenced through the MiSeq Illumina platform. These sequences were deposited in GenBank and compared with reference genomes. Prior to the execution of genomic and transcriptomic analyzes, composition of the essential oil extracted from BB.. ppssiiaaddiiooiiddeess used in the experiments was determined by gas chromatography with mass spectrometer (GC-MS), which demonstrated a higher amount of β-pinene in the fraction composed mainly by monoterpenes. This compound is often found in aromatic medicinal plants and also pointed as one of those responsible for their antimicrobial potential. The other results obtained in the present study indicate that the essential oil tested has a potential bacteriostatic activity at the concentration studied, and genes related to the virulence of the microorganism were less transcribed in its presence, contrary to what was observed for stress response genes, which presented higher transcription levels on that condition. Comparative genomics between the bacterial genomes sequenced in this work and the reference strains suggests a higher number of proteins expressed in LL.. mmoonnooccyyttooggeenneess serotype 4b related to the defense and metabolism of the microorganism, indicating mechanisms that may be involved with the greater ability of this serotype to cause human listeriosis.