991 resultados para root-nodule bacteria


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Hyoscyamine 60-hydroxylase (H6H: EC 1.14.11.11), a key enzyme at the terminal step of tropane alkaloid biosynthesis, converts hyoscyamine to scopolamine. The accumulation of scopolamine in different organs, in particular the aerial parts for storage, is subject to the expression of hyoscyamine 6-phydroxylase as well as its transport from the site of synthesis. To understand the molecular basis of this regulation, we have analyzed, in parallel, the relative levels of hyoscyamine and scopolamine, and the accumulation of H6H (both protein and transcript) in leaves, stems and roots of D. metel. The root, stem and leaf tissues all contain about 0.51-0.65 mg g(-1) dry weight of scopolamine. Hyoscyamine content was extremely low in leaf and stem tissues and was about 0.28 mg g(-1) dry weight in the root tissue. H6H protein and its transcript were found only in roots but not in the aerial parts viz. stems and leaves. The immunolocalization studies performed on leaf, stem, root as well as hairy root tissues showed that H6H was present only in the pericycle cells of young lateral and hairy roots. These studies suggest that the conversion of hyoscyamine to scopolamine takes place in the root pericycle cells, and the alkaloid biosynthesized in the roots gets translocated to the aerial parts in D. metel. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

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Epidemiological and experimental studies suggest that changes in gut microbial balance are associated with increases in the prevalence of allergic diseases. Probiotics are proposed to provide beneficial immunoregulatory signals which aid in oral tolerance achievement and alleviation of symptoms of allergic diseases. The present study evaluates both the immunological mechanisms of probiotics in infants with allergic diseases and their preventive aspect among infants prone to allergy. Furthermore, the purpose of the study was to characterise the immunological features of cord blood mononuclear cells (CBMCs) in infants at high genetic risk for allergy. GATA-3 expression (p = 0.03), interleukin (IL) -2(p = 0.026), and IL-5 (p = 0.013) secretion of stimulated CBMCs were higher in IgE-sensitized infants at age 2 than in non-allergic, non-sensitized infants. Lactobacillus GG (LGG) treatment increased secretion of IFN-γ by PBMCs in vitro in infants with cow s milk allergy (CMA) (p = 0.006) and in infants with IgE-associated eczema (p = 0.017), when compared to levels in the placebo group. A probiotic mixture, increased secretion of IL-4 by PBMCs in vitro in infants with CMA (p = 0.028), when compared with placebo-group levels. The LGG treatment induced higher plasma C-reactive protein (CRP) (p = 0.021) and IL-6 (p = 0.036) levels in infants with IgE-associated eczema than in the placebo group. The probiotic mixture induced higher plasma IL-10 levels in infants with eczema (p = 0.016). In the prevention study of allergic dis-eases, the infants receiving the probiotic mixture had higher plasma levels of CRP (p = 0.008), total IgA (p = 0.016), total IgE (p = 0.047), and IL-10 (p = 0.002) than did infants in the placebo group. Increased CRP level at age 6 months was associated with a decreased risk for eczema at age 2 not only in the infants who received probiotics but also in the placebo group (p = 0.034). In conclusion, the priming of the GATA-3 and IL-5 pathway can occur in utero, and a primary feature of T-cells predisposing to IgE-sensitization seems to directly favour Th2 deviation. LGG treatment induced increased plasma levels of CRP and IL-6 in infants with IgE-associated eczema, suggesting an activation of innate immu-nity. The probiotic mixture, when given to allergy-prone infants, induced inflammation, detected as increased plasma CRP levels, which at age 6 months was associated with decreased risk for eczema at age 2.The probiotic-induced response in allergy prone infants was characterized by their higher plasma IL-10, total IgE, and CRP levels, without induction of an allergen-specific IgE response. In this respect, the probiotics in infancy appear to induce protective immune profiles that are characteristic for chronic low-grade inflammation, a response resembling that of helminth-like infections.

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The spread of multidrug-resistant (MDR) bacteria has reached a threatening level. Extended-spectrum betalactamase- producing enterobacteriaceae (ESBLE) are now endemic in many hospitals worldwide as well as in the community, while resistance rates continue to rise steadily in Acinetobacter baumannii and Pseudomonas aeruginosa [1]. Even more alarming is the dissemination of carbapenemase-producing enterobacteriaceae (CPE), causing therapeutic and organizational problems in hospitals facing outbreaks or endemicity. This context could elicit serious concerns for the coming two decades; nevertheless, effective measures exist to stop the amplification of the problem and several axes of prevention remain to be fully exploited, leaving room for realistic hopes, at least for many parts of the world...

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Most studies exploring the role of upper airway viruses and bacteria in paediatric acute respiratory infections (ARI) focus on specific clinicaldiagnoses and/or do not account for virus–bacteria interactions. We aimed to describe the frequency and predictors of virus and bacteria codetection in children with ARI and cough, irrespective of clinical diagnosis. Bilateral nasal swabs, demographic, clinical and risk factor data were collected at enrollment in children aged <15 years presenting to an emergency department with an ARI and where cough was a symptom. Swabs were tested by polymerase chain reaction for 17 respiratory viruses and seven respiratory bacteria. Logistic regression was used to investigate associations between child characteristics and codetection of the organisms of interest. Between December 2011 and August 2014, swabs were collected from 817 (93.3%) of 876 enrolled children, median age 27.7 months (interquartile range13.9–60.3 months). Overall, 740 (90.6%) of 817 specimens were positive for any organism. Both viruses and bacteria were detected in 423 specimens (51.8%). Factors associated with codetection were age (adjusted odds ratio (aOR) for age <12 months = 4.9, 95% confidence interval (CI) 3.0, 7.9; age 12 to <24 months = 6.0, 95% CI 3.7, 9.8; age 24 to <60 months = 2.4, 95% CI 1.5, 3.9), male gender (aOR 1.46; 95% CI 1.1, 2.0), child care attendance (aOR 2.0; 95% CI 1.4, 2.8) and winter enrollment (aOR 2.0; 95% CI 1.3, 3.0). Haemophilus influenzae dominated the virus–bacteria pairs. Virus–H. influenzae interactions in ARI should be investigated further, especially as the contribution of nontypeable H. influenzae to acute and chronic respiratory diseases is being increasingly recognized.

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In the absence of specific treatable mutations, platinum-based chemotherapy remains the gold standard of treatment for lung cancer patients. However, 5-year survival rates remain poor due to the development of resistance and eventual relapse. Resistance to conventional cytotoxic therapies presents a significant clinical challenge in the treatment of this disease. The cancer stem cell (CSC) hypothesis suggests that tumors are arranged in a hierarchical structure, with the presence of a small subset of stem-like cells that are responsible for tumor initiation and growth. This CSC population has a number of key properties such as the ability to asymmetrically divide, differentiate and self-renew, in addition to having increased intrinsic resistance to therapy. While cytotoxic chemotherapy kills the bulk of tumor cells, CSCs are spared and have the ability to recapitulate the heterogenic tumor mass. The identification of lung CSCs and their role in tumor biology and treatment resistance may lead to innovative targeted therapies that may ultimately improve clinical outcomes in lung cancer patients. This review will focus on lung CSC markers, their role in resistance and their relevance as targets for future therapies.

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The study focuses on the emergence of tuberculosis as a public health problem and the development of the various methods to counteract it in Finland before the introduction of efficient methods of treatment in the 1940s and 50s. It covers a time period from year 1882 when the tuberculosis bacterium was identified to the 1930s when the early formation of tuberculosis work became established in Finland. During this time there occurred important changes in medicine, public health thinking and methods of personal health care that have been referred to as the bacteriological revolution. The study places tuberculosis prevention in this context and shows how the tuberculosis problem affected the government of health on all these three dimensions. The study is based on foucauldian analytics of government, which is supplemented with perspectives from contemporary science and technology studies. In addition, it utilises a broad array of work in medical history. The central research materials consist of medical journals, official programs and documents on tuberculosis policy, and health education texts. The general conclusions of the study are twofold. Firstly, the ensemble of tuberculosis work was formed from historically diverse and often conflicting elements. The identification of the pathogen was only the first step in the establishment of tuberculosis as a major public health problem. Important were also the attention of the science of hygiene and statistical reasoning that dominated public health thinking in the late 19th century. Furthermore, the adoption of the bacteriological tuberculosis doctrine in medicine, public health work and health education was profoundly influenced by previous understanding of the nature of the illness, of medical work, of the prevention of contagious diseases, and of personal health care. Also the two central institutions of tuberculosis work, sanatorium and dispensary, have heterogeneous origins and multifarious functions. Secondly, bacteriology represented in this study by tuberculosis remodelled medical knowledge and practices, the targets and methods of public health policy, and the doctrine of personal health care. Tuberculosis provided a strong argument for specific causes (if not cures) as well as laboratory methods in medicine. Tuberculosis prevention contributed substantially to the development whereby a comprehensive responsibility for the health of the population and public health work was added to the agenda of the state. Health advice on tuberculosis and other contagious diseases used dangerous bacteria to motivate personal health care and redefined it as protecting oneself from the attacks of external pathogens and strengthening oneself against their effects. Thus, tuberculosis work is one important root for the contemporary public concern for the health of the population and the imperative of personal health care.

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Microorganisms exist predominantly as sessile multispecies communities in natural habitats. Most bacterial species can form these matrix-enclosed microbial communities called biofilms. Biofilms occur in a wide range of environments, on every surface with sufficient moisture and nutrients, also on surfaces in industrial settings and engineered water systems. This unwanted biofilm formation on equipment surfaces is called biofouling. Biofouling can significantly decrease equipment performance and lifetime and cause contamination and impaired quality of the industrial product. In this thesis we studied bacterial adherence to abiotic surfaces by using coupons of stainless steel coated or not coated with fluoropolymer or diamond like carbon (DLC). As model organisms we used bacterial isolates from paper machines (Meiothermus silvanus, Pseudoxanthomonas taiwanensis and Deinococcus geothermalis) and also well characterised species isolated from medical implants (Staphylococcus epidermidis). We found that coating of steel surface with these materials reduced its tendency towards biofouling: Fluoropolymer and DLC coatings repelled all four biofilm formers on steel. We found great differences between bacterial species in their preference of surfaces to adhere as well as their ultrastructural details, like number and thickness of adhesion organelles they expressed. These details responded differently towards the different surfaces they adhered to. We further found that biofilms of D. geothermalis formed on titanium dioxide coated coupons of glass, steel and titanium, were effectively removed by photocatalytic action in response to irradiation at 360 nm. However, on non-coated glass or steel surfaces irradiation had no detectable effect on the amount of bacterial biomass. We showed that the adhesion organelles of bacteria on illuminated TiO2 coated coupons were complety destroyed whereas on non-coated coupons they looked intact when observed by microscope. Stainless steel is the most widely used material for industrial process equipments and surfaces. The results in this thesis showed that stainless steel is prone to biofouling by phylogenetically distant bacterial species and that coating of the steel may offer a tool for reduced biofouling of industrial equipment. Photocatalysis, on the other hand, is a potential technique for biofilm removal from surfaces in locations where high level of hygiene is required. Our study of natural biofilms on barley kernel surfaces showed that also there the microbes possessed adhesion organelles visible with electronmicroscope both before and after steeping. The microbial community of dry barley kernels turned into a dense biofilm covered with slimy extracellular polymeric substance (EPS) in the kernels after steeping in water. Steeping is the first step in malting. We also presented evidence showing that certain strains of Lactobacillus plantarum and Wickerhamomyces anomalus, when used as starter cultures in the steeping water, could enter the barley kernel and colonise the tissues of the barley kernel. By use of a starter culture it was possible to reduce the extensive production of EPS, which resulted in a faster filtration of the mash.

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Evidence has been presented to show that the autotrophic nitrifying organisms get stimulated in the mulberry rhizosphere. Three species of Pseudomonas, one each of Achromobacter and Bacillus capable of degrading methionine were shown to be stimulated in the rhizosphere. These bacteria were capable of reversing the inhibitory effect of methionine on soil nitrification. Two of them were able to form nitrite from methionine. The possibility that the increased nitrifying activity in the mulberry rhizosphere in the presence of methionine found in mulberry root exudations was the result of the activity of these organisms was suggested.

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Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment.The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. (C) 2010 Elsevier B.V. All rights reserved.

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Dynamics of raw milk associated bacteria during cold storage of raw milk and their antibiotic resistance was reviewed, with focus on psychrotrophic bacteria. This study aimed to investigate the significance of cold storage of raw milk on antibiotic-resistant bacterial population and analyse the antibiotic resistance of the Gram-negative antibiotic-resistant psychrotrophic bacteria isolated from the cold-stored raw milk samples. Twenty-four raw milk samples, six at a time, were obtained from lorries that collected milk from Finnish farms and were stored at 4°C/4 d, 6°C/3 d and 6°C/4 d. Antibiotics representing four classes of antibiotics (gentamicin, ceftazidime, levofloxacin and trimethoprim-sulfamethoxazole) were used to determine the antibiotic resistance of mesophilic and psychrotrophic bacteria during the storage period. A representative number of antibiotic-resistant Gram-negative isolates retrieved from the cold-stored raw milk samples were identified by the phenotypic API 20 NE system and a few isolates by the 16S rDNA gene sequencing. Some of the isolates were further evaluated for their antibiotic resistance by the ATB PSE 5 and HiComb system. The initial average mesophilic counts were found below 105 CFU/mL, suggesting that the raw milk samples were of good quality. However, the mesophilic and psychrotrophic population increased when stored at 4°C/4 d, 6°C/3 d and 6°C/4 d. Gentamicin- and levofloxacin-resistant bacteria increased moderately (P < 0.05) while there was a considerable rise (P < 0.05) of ceftazidime- and trimethoprim-sulfamethoxazole-resistant population during the cold storage. Of the 50.9 % (28) of resistant isolates (total 55) identified by API 20 NE, the majority were Sphingomonas paucimobilis (8), Pseudomonas putida (5), Sphingobacterium spiritivorum (3) and Acinetobacter baumanii (2). The analysis by ATB PSE 5 system suggested that 57.1% of the isolates (total 49) were multiresistant. This study showed that the dairy environment harbours multidrug-resistant Gramnegative psychrotrophic bacteria and the cold chain of raw milk storage amplifies the antibioticresistant psychrotrophic bacterial population.

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Bacteria growing in paper machines can cause several problems. Biofilms detaching from paper machine surfaces may lead to holes and spots in the end product or even break the paper web leading to expensive delays in production. Heat stable endospores will remain viable through the drying section of paper machine, increasing the microbial contamination of paper and board. Of the bacterial species regularly found in the end products, Bacillus cereus is the only one classified as a pathogen. Certain B. cereus strains produce cereulide, the toxin that causes vomiting disease in food poisonings connected to B. cereus. The first aim of this thesis was to identify harmful bacterial species colonizing paper machines and to assess the role of bacteria in the formation of end product defects. We developed quantitative PCR methods for detecting Meiothermus spp. and Pseudoxanthomonas taiwanensis. Using these methods I showed that Meiothermus spp. and Psx. taiwanensis are major biofoulers in paper machines. I was the first to be able to show the connection between end product defects and biofilms in the wet-end of paper machines. I isolated 48 strains of primary-biofilm forming bacteria from paper machines. Based on one of them, strain K4.1T, I described a novel bacterial genus Deinobacterium with Deinobacterium chartae as the type species. I measured the transfer of Bacillus cereus spores from packaging paper into food. To do this, we constructed a green fluorescent protein (GFP) labelled derivative of Bacillus thuringiensis and prepared paper containing spores of this strain. Chocolate and rice were the recipient foods when transfer of the labelled spores from the packaging paper to food was examined. I showed that only minority of the Bacillus cereus spores transferred into food from packaging paper and that this amount is very low compared to the amount of B. cereus naturally occurring in foods. Thus the microbiological risk caused by packaging papers is very low. Until now, the biological function of cereulide for the producer cell has remained unknown. I showed that B. cereus can use cereulide to take up K+ from environment where K+ is scarce: cereulide binds K+ ions outside the cell with high affinity and transports these ions across cell membrane into the cytoplasm. Externally added cereulide increased the growth rate of cereulide producing strains in medium where potassium was growth limiting. In addition, cereulide producing strains outcompeted cereulide non-producing B. cereus in potassium deficient environment, but not when the potassium concentration was high. I also showed that cereulide enhances biofilm formation of B. cereus.

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The aim of this thesis was to unravel the functional-structural characteristics of root systems of Betula pendula Roth., Picea abies (L.) Karst., and Pinus sylvestris L. in mixed boreal forest stands differing in their developmental stage and site fertility. The root systems of these species had similar structural regularities: horizontally-oriented shallow roots defined the horizontal area of influence, and within this area, each species placed fine roots in the uppermost soil layers, while sinker roots defined the maximum rooting depth. Large radial spread and high ramification of coarse roots, and the high specific root length (SRL) and root length density (RLD) of fine roots indicated the high belowground competitiveness and root plasticity of B. pendula. Smaller radial root spread and sparser branching of coarse roots, and low SRL and RLD of fine roots of the conifers could indicate their more conservative resource use and high association with and dependence on ectomycorrhiza-forming fungi. The vertical fine root distributions of the species were mostly overlapping, implying the possibility for intense belowground competition for nutrients. In each species, conduits tapered and their frequency increased from distal roots to the stem, from the stem to the branches, and to leaf petioles in B. pendula. Conduit tapering was organ-specific in each species violating the assumptions of the general vascular scaling model (WBE). This reflects the hierarchical organization of a tree and differences between organs in the relative importance of transport, safety, and mechanical demands. The applied root model was capable of depicting the mass, length and spread of coarse roots of B. pendula and P. abies, and to the lesser extent in P. sylvestris. The roots did not follow self-similar fractal branching, because the parameter values varied within the root systems. Model parameters indicate differences in rooting behavior, and therefore different ecophysiological adaptations between species.