Studies indicate an association between both term labour (TL) and preterm labour (PTL) and the presence of uterine inflammatory cytokines and leukocyte infiltration. We hypothesized that peripheral leukocytes are recruited to uterine tissues by locally produced cytokines where they contribute to the initiation of TL and PTL. The cytokine expression profile was analyzed using an in vivo mouse model of gestation and two PTL models (Lipopolysaccharide- and RU486-induced). Myometrial neutrophil and macrophage infiltration was also studied. My results demonstrate that macrophage infiltration precedes neutrophil infiltration during late gestation and that both leukocyte subsets increase during PTL and further increase post partum. These changes in leukocyte numbers are associated with significant changes in multiple myometrial cytokines with TL and RU486-induced PTL showing similar cytokine profiles. Importantly, post partum involution, the process by which the uterus completes the reproductive cycle and returns to its pre-pregnant state, appears similar in all three models.

Acute Respiratory Distress Syndrome (ARDS) following hemorrhagic shock/resuscitation (S/R) is an important contributor to late morbidity and mortality in trauma patients. S/R promotes ARDS by inducing oxidative stress that primes cells of the innate immune system for excessive responsiveness to small inflammatory stimuli, termed the “twohit” hypothesis. Activated alveolar macrophages (AM) play a central role and when recovered from S/R animals exhibit an exaggerated responsiveness to lipopolysaccharide (LPS) with increased activation of the proinflammatory transcription factor NF-κB, and augmented expression of cytokines. LPS triggers AM signalling through Toll like receptor 4 (TLR4), which resides in plasma membrane lipid rafts. The objective of this work is to define cellular mechanisms of macrophage priming by oxidative stress following shock resuscitation. The main hypothesis investigated is that altered cellular distribution of TLR4 can lead to macrophage priming and antioxidant resuscitation strategies can diminish these effects. AM of rodents, exposed in vivo to oxidant stress following S/R, increase their surface levels of TLR4, which in turn results in augmented NF-κB translocation in response to small doses of LPS. Furthermore, in vitro H2O2 treatment of RAW 264.7 macrophages results in similar TLR4 surface translocation. Depletion of intracellular calcium, disruption of the cytoskeleton or inhibition of the Src kinases prevents the H2O2-induced TLR4 translocation, suggesting the involvement of receptor exocytosis. Further, fluorescent resonance energy iii transfer between TLR4 and lipid rafts as well as biochemical raft analysis demonstrated that oxidative stress redistributes TLR4 to surface lipid rafts. Preventing the oxidant-induced movement of TLR4 to lipid rafts using methyl-ß-cyclodextrin precluded the increased responsiveness of cells to LPS after H2O2 treatment. Further, AM priming by oxidative stress can be diminished by early exposure to resuscitation regimens with direct or indirect systemic antioxidant effects, such as 25% albumin, N-acetylcysteine and hypertonic saline. Hyperosmolarity was found to modulate AM TLR4 gene and protein expression. Collectively, these studies suggest a novel mechanism whereby oxidative stress might prime the responsiveness of cells of the innate immune system. Targeting the TLR4 signalling pathway early during shock resuscitation may represent an anti-inflammatory strategy able to ameliorate late morbidity and mortality following S/R.

Vibrio vulnificus are marine bacteria causing fatal septicemia through wound infections or consumption of contaminated seafood. V. vulnificus is an excellent model for the study of surface polysaccharides, as it is capable of synthesizing capsular polysaccharide (CPS), lipopolysaccharide (LPS) and exopolysaccharide (EPS). V. vulnificus strains exhibit a multitude of carbotypes that evolve through unknown mechanisms. CPS is a confirmed virulence factor, but the genetics of its biosynthesis are unknown. The main objective of these experiments was to gain insight into the biosynthesis, regulation and evolution of ATCC 27562 outer surface polysaccharides. A miniTn10 transposon (Tn) system was used for mutagenesis and single insertions were confirmed through Southern analysis. A novel 25 kb CPS biosynthesis locus was identified through sequencing of regions surrounding Tn insertions; a region encoding putative LPS core biosynthetic functions was identified adjacent to the CPS cluster. The CPS locus contained features of O-antigen biosynthetic loci and was unusual in carrying characteristics of both group I and IV capsular biosynthetic loci. Mutations in this region resulted in elimination of CPS and LPS, and both were shown to be dependent on the activity of the polymerase Wzy. Evidence is presented here supporting horizontal transfer (HT) as a contributor to V. vulnificus CPS evolution. CPS regions of V. vulnificus 27562, YJ016 and CMCP6 contain strain specific genes surrounded by conserved regions, suggestive of HT. Moreover, a CPS locus virtually identical to that of 27562 was discovered in Shewanella putrefaciens strain 200. 27562 CPS is distinctive as it contains N-acetylmuramic acid. Genes encoding murA and murB activities were identified within the cluster and shown to be functionally redundant, supporting HT acquisition of this region. A screen of V. vulnificus gDNA library using CPS biosynthesis and transport mutants identified a cyclic diguanylate cyclase, dcpA. dcpA-mediated increase in cyclic diguanylate lead to EPS production, rugosity phenotypes and enhanced biofilm formation. Interestingly, virulence and motility were not affected suggesting complexity of cyclic diguanylate regulation in V. vulnificus, supported by the large number of cyclic diguanylate related proteins in Vulnificus strains.

Endotoxin recognition by the innate immune receptor CD14 is a critical part of the innate immune system’s early detection and activation of the inflammatory response during microbial invasion. The differential recognition and high affinity binding of endotoxins from gram-negative and gram-positive bacteria is performed by the innate immune receptor CD14. Upon endotoxin binding, CD14 transfers the specific endotoxins to a Toll-like receptor signaling complex, which is responsible for initiating the intracellular signaling cascade. In the presence of overwhelming infection, the effects of CD14 lead to the over-activation of the inflammatory response, which results in the life threatening condition known as sepsis. Preparation of a 15N isotopically labeled truncated version of soluble CD14, using Pichia pastoris, allowed direct structural observation of the binding interaction between CD14 and two endotoxin ligands, lipopolysaccharide (LPS) and lipoteichoic acid (LTA), from gram-negative and gram-positive bacteria, respectively using solution NMR spectroscopy. These studies revealed that CD14 uses both a common set of residues, and endotoxin specific subsets of residues, to bind LPS and LTA. To further investigate the structural features of each endotoxin recognized by CD14, 13C 15N isotopically labeled Kdo2–Lipid A, a fully active chemically defined gram-negative endotoxin, and LTA lipid anchor, the minimal unit of LTA, were produced. This allowed detailed NMR spectral mapping of these agonist ligands bound to sCD14 which identified, for the first time, structural regions and features in each that are strongly affected during complex formation with sCD14. Additionally, the presence of differential dynamic behavior was seen in both CD14 and the ligands upon complexation. This behavior suggests a likely role for dynamics in the mechanism of pattern recognition by CD14, which uses the dynamic ability of specific residue combinations to differentially affect endotoxin binding. Using NMR, the dynamic behavior of CD14 was further investigated using temperature and pH-dependence studies of isotopically labeled CD14. These studies clearly demonstrated the presence of multiple conformations for several residues, and may provide a possible explanation for the broad specificity of ligand binding by CD14. In addition, the spin-labeling of isotopically labeled lipid A enabled the collection of intermolecular distances on CD14 bound lipid A.

Master of Science / Periodontal disease is one of the most widespread diseases in humans and is characterised by chronic gingival inflammation and B cell accumulation and resorption of the crest of alveolar bone with subsequent loss of teeth. Porphyromonas gingivalis has been identified as a putative aetiological agent for periodontitis. The aim of the research presented in this thesis was to investigate, using in vitro systems, the responses of autoreactive B-1 and B-2 cells to enterobacterial and nonenterobacterial lipopolysaccharide (LPS) to shed light on the pathogenesis of chronic periodontitis and other diseases involving B cell accumulation and autoantibody production. The hypotheses tested were: (1) B cells respond differently to enterobacterial and non-enterobacterial LPS. (2) B-1 cells are activated by a lower concentration of LPS than B-2 cells. (3) LPS stimulation results in preferential accumulation of B-1 cells. Findings consistent with these hypotheses would provide new evidence for different roles for B-1 and B-2 cells in immune responses and that LPS stimulation could lead to B-1 cell accumulation in diseases thus characterised. Initial experiments investigated the responses of representative B-1 (CH12) and B-2 (WEHI-279) cell lines to preparations of P. gingivalis and Salmonella enteritidis LPS utilising flow cytometric and quantitative molecular methods. The cell lines responded differently to the two LPS preparations. There were significant but limited effects on viability and proliferation in the WEHI-279 cell line, but no significant changes in mRNA expression levels for genes including Toll-like receptors (TLR2, TLR4, RP105), immunoglobulin (IgM), cytokines (IL-6, IL-10), co-stimulatory molecules (CD80, CD86), and regulators of apoptosis (Bcl-2, Bax). In the CH12 cell line however, LPS stimulation had greater effect. Addition of S. enteritidis LPS from a threshold level of 100ng/mL was found to rescue the cells from death, reflected by the percentage viability and proliferation. Stimulation of CH12 cells with S. enteritidis LPS also led to a decrease in expression of RP105 mRNA, which may be part of a negative feedback loop. Interestingly, stimulation with low concentrations P. gingivalis LPS appeared to inhibit proliferation but high LPS concentrations stimulated proliferation of CH12 cells, although no further significant effects were noted in other analyses. Evidence was found that CH12 cells have a high basal level of activation. This suggests that this line is constitutively activated. Stimulation with P. gingivalis or S. enteritidis LPS did not affect the level of CD80 mRNA expression. It is possible that the CH12 line constitutively expresses a maximal level of CD80 (and possibly CD86) and further stimulation will not cause any increase. Since S. enteritidis LPS appeared to have more pronounced effects on both B cell populations, this LPS was used to further investigate B cell subset responses in a mixed splenocyte culture system. Experiments examining percentage viability and number of viable cells indicated that B-1 and B-2 B cells responded differently to LPS stimulation. A threshold level for B-2 cell response (significant increase in cell number) was found to be 100ng/mL LPS, in contrast to the B-1 B cell subset which were only significantly different to the unstimulated cells when stimulated with 50μg/mL LPS. By examining the expression of CD80, the majority of murine splenic B-1 cells were found to activated prior to any LPS stimulation in vitro. In contrast, the B-2 subset showed significant increase in CD80 expression only at high (≥10μg/mL) LPS concentrations. Studies of the division index of B-1 and B-2 cells showed a significant response in both subsets following stimulation with 1μg/mL and 10μg/mL LPS. However, overall, the results are inconsistent with LPS driving the preferential accumulation of B-1 cells in disease states. These experiments provided useful evidence that supported the idea that B-1 and B-2 cells respond differently to LPS. However, these studies were unable to directly address the role of P. gingivalis LPS in periodontitis. It may be that P. gingivalis LPS could have different effects to S. enteritidis LPS on primary B cells. It is still possible that B-1 cells may be more sensitive to P. gingivalis, as opposed to S. enteritidis LPS. Studies by other groups have suggested that the TH1/TH2 profile is skewed towards TH2 in chronic periodontitis and that P. gingivalis may drive this shift via its ability to signal through TLR2 (and modulate TLR4 signalling). Further, recent studies in our laboratories have found that P. gingivalis gingipains are able to polyclonally activate B cells and to break down both IFNγ and IL-12. Future studies should further examine the effects of B-1 and B-2 interactions in the mixed lymphocyte system together with subsequent studies utilising human periodontitis biopsies. The results presented in this thesis, together with work undertaken by other investigators, suggests that LPS could perturb the normal homeostatic mechanisms of the B-1 B cell-subset and increase polyclonal activation therefore contributing to the genesis of pathologies such as chronic periodontitis.

Techn. Universiẗat, Diss., 2005--Darmstadt.

Preterm labour (PTL) is defined as labour before 37 completed weeks of gestation. Despite advances in medical research, PTL remains a major clinical problem. Preterm birth (PTB) rates range from approximately 5-18% worldwide. Importantly, PTB is the leading cause of childhood morbidity and mortality. PTL is difficult to predict and the aetiology is poorly understood but infection and inflammation are believed to be major factors. It has been suggested that the presence of intrauterine infection or inflammation may initiate the pathological, preterm activation of the inflammatory cascade associated with term labour. Therefore, PTL therapeutics should aim to inhibit these inflammatory pathways. Statins, 5-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, are potent inhibitors of cholesterol biosynthesis, which act on the mevalonate pathway. In addition to their lipid-lowering effects, statins also have anti-inflammatory and anti-contraction properties. The hypothesis of this thesis was that statins will prevent PTB by reducing inflammation. The aims of this thesis were firstly to investigate the effect of the statins, simvastatin and pravastatin, on inflammation and contractility in a pregnant human myometrial cell line. Secondly, to determine whether simvastatin and/or pravastatin can prevent PTB or improve neonatal outcome in a lipopolysaccharide (LPS)-induced mouse model of PTB. Myometrial cells were either co-treated with LPS and simvastatin/pravastatin, pretreated with simvastatin/pravastatin or treated with simvastatin/pravastatin post-LPS stimulation. The effect of statin treatment on the mRNA expression and the release of inflammatory mediators was then investigated. Simvastatin treatment reduced LPS-induced inflammation by both lowering the expression of pro-inflammatory mediators and increasing the expression of anti-inflammatory mediators. Pravastatin treatment did not alter the expression of inflammatory mediators following LPS stimulation. The effect of simvastatin on the contraction of myometrial cells was investigated by embedding the cells in rat tail collagen to form gels. As these are smooth muscle cells, basal contraction was observed causing the gel size to reduce. When LPS was introduced, this caused the gels to contract further than the vehicle treated gels. Simvastatin attenuated the contraction of the myometrial cells, both alone and in the presence of LPS. These effects were reversed by the addition of mevalonate pathway metabolites, mevalonate and geranylgeranyl pyrophosphate (GG-PP) but not by farnesyl pyrophosphate (F-PP). Simvastatin also lowered levels of phosphorylated myosin light chain (pMLC) in the myometrial cells, which is essential for smooth muscle contraction. Again, this effect was abolished by mevalonate and GG-PP but not F-PP. It is hypothesised that simvastatin attenuated myometrial cell contraction by inhibiting Rho isoprenylation by GG-PP, preventing Rho-associated kinase (ROCK) activation, which then prevented the phosphorylation of MLC. A mouse model of intrauterine LPS-induced PTB was utilised to investigate the effect of statin treatment on PTB and fetal survival. Mice received an intraperitoneal injection of pravastatin (10μg) or simvastatin (20μg or 40μg) on gestational day (D)16. This was followed by ultrasound-guided intrauterine injection of LPS (1μg) on D17 and another pravastatin/simvastatin treatment two hours later. When mice were treated with LPS, 77.8% of mice delivered preterm. When mice received LPS and 20μg simvastatin, 50% delivered preterm. However, when mice were treated with LPS and 40μg simvastatin, 40% delivered preterm, more pups were born alive and uterine pro-inflammatory mRNA expression was downregulated. Conversely, pravastatin did not prevent PTB or improve the percentage of live born pups. In summary, simvastatin treatment exerted anti-inflammatory and anti-contraction effects on human myometrial cells in vitro. The anti-contractile properties were likely due to the inhibition of the Rho/ROCK pathway. Furthermore, in our LPS-induced mouse model of PTB, fewer mice delivered preterm with simvastatin treatment, simvastatin attenuated LPS-induced pup mortality and reduced uterine inflammatory gene expression. These results suggest that statin therapy may be a novel treatment for PTL.

Systemic inflammation is thought to be an important driver in chronic neurodegeneration. During systemic infection, the inflammatory status of the periphery is communicated to the brain and conserved sickness behaviours initiated. However, in the context of dementia the same inflammatory stimulus might trigger delirium. Delirium is a severe, transient neuropsychiatric condition characterised by altered levels of arousal, inattention, cognitive deficits and psychoses. Delirium and systemic inflammation exacerbate the trajectory of pre-existing dementia, and are associated with increased risk of future dementia. Accumulating experimental studies suggest microglia are “primed” by chronic neurodegeneration, such that a subsequent inflammatory insult – central or systemic – induces an increased inflammatory response which manifests as exaggerated sickness behaviours. To date there have been no studies of microglial priming in the context of pure tau pathology, without amyloid pathology, and none investigating acute sickness behaviour in such a model. The overarching aim of this thesis is to address this gap in the literature and further our understanding of the interactions between systemic inflammation, neuroinflammation and neurodegeneration in the context of tauopathy. The P301S mouse over-expresses human mutant tau protein under the Thy1.2 promoter. It develops hyperphosphorylated and insoluble tau accumulations and progressive neuronal loss. Consequently, P301S mice develop progressive hind limb paralysis. This study identified the horizontal bar task, a test of motor control and coordination, conducted at weekly intervals from 8-22 weeks of age, as a non-invasive measure of disease progression. In addition, a detailed temporal profile of pathological hallmarks at 8, 9, 10, 11, 12, 16 and 20 weeks of age was determined. Key results presented here demonstrate progressive, superficial neuronal loss in the cortex of P301S mice, with associated astrogliosis and surprisingly this occurs in the absence of apparent cortical microgliosis. In stark contrast, there is progressive microgliosis in the spinal cord of P301S mice. On this background, lipopolysaccharide (LPS), a chemical moiety found on the outer surface of gram-negative bacteria, was used to mimic a systemic bacterial infection. P301S mice and C57BL/6 control mice were injected, at 10 or 16 weeks of age, intraperitoneally with 500 μg/kg LPS or saline and were monitored in the following hours and weeks. Acutely, P301S mice showed signs of an exaggerated, longer lasting sickness response. Importantly, exaggerated acute symptoms extended beyond those typically associated with sickness behaviour; LPS induced an exaggerated acute impairment of horizontal bar performance in P301S mice and not C57BL/6 mice – a function which is known to be impaired in P301S mice later in disease. Impairments were age-dependent in terms of timing of injection. These data suggest an interaction between acute infection and existing CNS vulnerability leading to acute neurological dysfunction that is not a feature observed in sickness in a normal animal. LPS-injected P301S mice also showed, again age-dependent, increased rate of decline in motor performance compared with controls. There was no evidence of microglial priming in P301S mice. LPS caused an acute increase in AT8-positive phospho-tau however this did not persist until end stage. At 22 weeks of age there was significant disease-associated cortical neuronal loss in the vehicle-injected P301S mice, and additional superficial cortical neuronal loss in LPS-injected P301S mice and control mice. There was significant IBA1-positive microgliosis in the spinal cord of P301S mice at end stage which was further increased in LPS-injected P301S mice. Taken together these data indicate a clear and clinically relevant interaction between systemic inflammation and tau-associated neuropathology with acute and long-term functional consequences. In the absence of evidence of microglial priming, future work will explore potential mechanisms.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo do presente estudo foi investigar o envolvimento do estresse oxidativo na lesão pulmonar aguda (LPA) induzida por lipopolissacarídeo (LPS) e as repercussões inflamatórias, estruturais e funcionais, através de análises bioquímicas de estresse oxidativo, prova de função pulmonar, análise histológica e RT-PCR para citocinas e fatores de transcrição pró-inflamatórios. Na primeira etapa foram utilizados camundongos machos C57BL6 foram divididos em sete grupos: Grupo controle (CTR) (50 &#956;L de solução fisiológica) administrados via intratraqueal [it], LPS 6 horas (10 &#956;L de LPS) [it], LPS 12 horas (10 &#956;L de LPS) [it], LPS 24 horas (10 &#956;L de LPS) [i], LPS 48 horas (10 &#956;L de LPS). Para verificar que as alterações observadas eram estresse oxidativo dependentes camundongos machos C57BL6 foram pré-tratados com N-acetilcisteína (NAC) 1 hora antes do estímulo com LPS e sacrifícados 24 horas depois do estímulo com LPS. Os animais foram divididos da seguinte forma: Grupo LPS 24 horas (10 &#956;L) [it], grupo NAC 40 mg/kg (gavagem) + LPS (10 &#956;L) [it] e grupo NAC 100 mg/kg (gavagem) + LPS (10 &#956;L) [it]. O sistema antioxidante enzimático protegeu o pulmão do estresse oxidativo nas primeiras 12 horas. O estresse oxidativo foi caracterizado em 24 horas e em 48 horas observou-se falência do sistema antioxidante enzimático. Parâmetros de função pulmonar se mostraram alterados nos grupo estimulados com LPS principalmente no grupo LPS. A elastância (p<0,001), resistência de via aérea periférica (&#916;P2) (p<0,001), resistência de via aérea central (&#916;P1) (p<0,001) e resistência de via aérea total (&#916;Ptot) (p<0,001) se mostraram principlamente alteradas no grupo LPS 24 horas. O pré-tratamento com NAC impediu o aumento dos parâmetros de elastância (p<0,001), resistência de via aérea periférica (&#916;P2) (p<0,001) resistência de via aérea central (&#916;P1) (p<0,05) e resistência de via aérea total (&#916;Ptot) (p<0,001) comparado com o grupo LPS 24 horas. As alterações histológicas como espessamento de septo alveolar, influxo de células inflamatórias e hemorragia mostraram-se tempo dependentes. O pré-tratamento NAC impediu as alterações observadas nos grupo estimulados com LPS. Alterações inflamatórias foram observadas no grupo estimulado com LPS como IL-6 (p<0,001), iNOS (p<0,001), COX2 (p<0,05), TNF-&#945; (p<0,001) e NF&#954;B (p<0,001) quando comparados ao grupo controle. O pré-tratamento com NAC impediu o aumento desses parâmetros como IL-6 (p<0,001), iNOS (p<0,001), COX2 (p<0,05), TNF-&#945; (p<0,05) e NF&#954;B (p<0,001) quando comparados ao grupo LPS 24 horas. Nossos resultados sugerem que o estresse oxidativo desempenha um papel importante nas respostas inflamatórios, estruturais e funcionais no modelo de LPA induzido por LPS e que essas alterações são estresse oxidativo dependentes. / The aim of this study was to investigate the involvement of oxidative stress in acute lung injury (ALI) induced by lipopolysaccharide (LPS) and inflammatory effects, structural and functional, through biochemical analysis of oxidative stress, pulmonary function test, histological and RT-PCR for cytokines and transcription factors pro-inflammatory. In the first stage were used C57BL6 male mice were divided into seven groups: control group (CTR) (50 &#956;L saline) administered via intratracheal [it], LPS 6 hours (10 &#956;L of LPS) [it], LPS 12 hours (10 &#956;L of LPS) [it], LPS 24 hours (10 &#956;L of LPS) [it], LPS 48 hours (10 &#956;L of LPS). To confirm that the observed changes were dependent on oxidative stress in C57BL6 male mice were pretreated with N-acetylcysteine (NAC) 1 hours before stimulation with LPS and sacrificed 24 hours after stimulation with LPS. The animals were divided as follows: LPS group 24 hours (10 &#956;L) [it], NAC group 40 mg / kg (gavage) + LPS (10 &#956;L) [it] NAC group and 100 mg / kg (gavage) + LPS (10 &#956;L) [it]. The enzymatic antioxidant system protected the lungs against oxidative stress in the first 12 hours. Oxidative stress was characterized in 24 hours and 48 hours there was failure of the enzymatic antioxidant system. Pulmonary function parameters were shown in the altered group stimulated with LPS mainly in the LPS group. Elastance (p <0,001), peripheral airway resistance (&#916;P2) (p <0,001), central airway resistance (&#916;P1) (p <0,001) and total airway resistance (&#916;Ptot) (p <0,001) if especially in the group showed altered LPS 24 hours. Pretreatment with NAC prevented the increase in elastance parameters (p <0,001), peripheral airway resistance (&#916;P2) (p <0,001) central airway resistance (&#916;P1) (p <0,05) and resistance total airway (&#916;Ptot) (p <0,001) compared with the LPS group 24 hours. Histological changes such as thickening of alveolar septa, inflammatory cells and hemorrhage proved to be time dependent. The NAC pretreatment prevented the changes observed in the group stimulated with LPS. Inflammatory changes were observed in the group stimulated with LPS and IL-6 (p <0,001), iNOS (p <0,001), COX2 (p <0,05), TNF-&#945; (p <0,001) and NF&#954;B (p <0,001) compared with the control group. Pretreatment with NAC prevented the increase of these parameters as IL-6 (p <0,001), iNOS (p <0,001), COX2 (p <0,05), TNF-&#945; (p <0,05) and NF&#954;B ( p <0,001) when compared with LPS 24 hours. Our results suggest that oxidative stress plays an important role in inflammatory responses, structural and functional model of ALI induced by LPS and that these changes are dependent oxidative stress.

Made available in DSpace on 2014-06-11T19:28:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-26Bitstream added on 2014-06-13T18:34:44Z : No. of bitstreams: 1 castellane_tcl_me_jabo.pdf: 528856 bytes, checksum: bad471ecc220d47ecbe832fa3f7acba8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O estabelecimento da simbiose é baseado em um complexo diálogo entre o rizóbio e a planta hospedeira. Polissacarídeos de superfície de origem rizobiana aparentam ser essenciais para o processo de infecção. A composição dos EPSs das estirpes de Rhizobium tropici SEMIA 40]7 e SEMIA 4080 diferiram quantitativamente. Os quatro tipos de fontes de carbono têm efeitos diferentes na concentração da galactose e glicose, sendo maior para SEMIA 4080 cultivada em meio contendo sacarose. Mesmo a estirpe SEMIA 4080, apresentando grande quantidade de exopolissacarídeos liberado na cultura, não apresenta diferenças significativas no número de nódulos em relação às inoculações com a estirpe SEMIA 4077, sendo esta última, a que apresenta pior desempenho quanto à massa seca dos nódulos. / The establishment of symbiosis is based on a complex molecular dialogue between rhizobia and host plant. Rhizobial surface polysaccharides appear to be essential for the infection processo The EPSs composition produced by Rhizobium tropici SEMIA 4077 and SEMIA 4080, differed quantitatively from one another. . Four types •of culture. media showed differential effects on the concentrations of the galactose and glucose, particularly the SEMIA 4080 strain, which was cultivated in sucrose medium. Even though the SEM IA 4080 strain produced a large quantity of EPS in culture, it was not significantly different from the number of nodules related to inoculations using strain SEMIA 4077.