Dissertations / Theses: 'Fumigants'

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Ren, YongLin, and n/a. "Carbonyl sulphide as a fumigant for grain and timber : efficacy towards organisms and formation of residues." University of Canberra. Human & Biomedical Sciences, 1997. http://erl.canberra.edu.au./public/adt-AUC20061107.120137.

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This thesis presents an investigation of carbonyl sulphide as a new fumigant and related methodology studies. The first part involved the investigation of a new fumigant - carbonyl sulphide, which has the potential to replace methyl bromide. Its biological response or activity was investigated, e.g. toxicity to target organisms and phytotoxicity, environmental and worker safety considerations. In the second investigation, analytical methods were developed for the determination of fumigant movement through timber and fumigant residues in grains as well as a method of chemical fractionation to determine the fate of carbonyl sulphide. A comprehensive literature review of 161 references in these two areas is reported. Carbonyl sulphide was highly toxic to adults of three coleopteran species tested, namely Rhyzopertha dominica (F.), Tribolium confusum du Val, and Sitophilus oryzae (L.), the most sensitive species was R. dominica. For 6 hr exposure at 25�C, the L(CxT)95 value for R. dominica, S. oryzae and T. confusum were, respectively, 36.48, 99.82 and 113.0mg h L-1. Carbonyl sulphide inhibited 100% of mould in wet wheat and more than 90% of mould on dry wheat at lOOmg L-1. Both carbonyl sulphide and hydrogen cyanide were low in phytotoxicity without affecting germination of wheat, at levels needed to control insects. Unlike hydrogen cyanide, carbonyl sulphide can be used at minimum levels without decreasing plumule length of wheat. Chemical data on the sorption of carbonyl sulphide are compared with data from methyl bromide. The levels of carbonyl sulphide in the headspace of five commodities (wheat, barley, paddy, sorghum and peanut) and timbers (hardwood and softwood) decay more slowly than do levels of methyl bromide. Carbonyl sulphide was blown through a column of wheat as easily as was phosphine and more easily than was methyl bromide, and its front was blown out faster than phosphine and methyl bromide. Movement of two fumigants (methyl bromide and carbonyl sulphide) through, and sorption on, softwood and hardwood were studied. Each fumigant was sorbed less on softwood than on hardwood and penetrated softwood better than hardwood. Carbonyl sulphide penetrated timber better than did methyl bromide, and was less sorbed on timber. A rapid method of solvent extraction was developed to enable rapid estimation of the amount on intact fumigant sorbed in wood. This procedure enabled near quantitative recovery of methyl bromide as either intact fumigant or as bromide ion. Carbonyl sulphide residue in unfumigated wheat was found to be around 25- SOppb. Carbonyl sulphide left little residue on fumigated grains. Desorption of carbonyl sulphide from the wheat was extremely fast, 85% of it was released after one day aeration which was very much greater than that of methyl bromide and carbon disulphide. After 6 days aeration the incorporation of 14COS on mungbean, wheat, paddy, rice and safflower was lower than 7Oppb (calculated as COS equivalent). Food value or nutritional quality of foodstuffs is not harmed by carbonyl sulphide fumigation. This result was assessed by identifying any nonreversible change or combined residues in biochemical fractions of commodities including lipids, protein, amino acids, carbohydrate, etc., and no irreversible reaction between carbonyl sulphide and any constituent such as B vitamin, atocopherol, lysine, maltose and starch. Fumigants did not affect lipids, although each fumigant was applied to wheat at exaggerated concentrations, nor wheat germ oil and canola oil treated with extremely high concentration of fumigants. Factors which affect analysis of fumigants including stability of chemicals in extraction solvent and partitioning of fumigant between solvent and air, were examined. The partition ratio, defined as the fumigant concentration in extraction solvent to that in the headspace, varied with fumigant. Methods for multi-fumigant analysis were developed or modified and gave high recoveries and efficiency. The procedure of Daft of solvent extraction followed by partitioning was modified by being performed in sealed flasks. This raised the recovery of carbonyl sulphide, methyl bromide, phosphine and carbon disulphide. Recoveries were near quantitative at levels down to 6-16ppb (w/w) for tested fumigants. Thus the modified Daft method can be adapted to enable determination of the main fumigants used on staple foodstuffs. Microwave irradiation method give higher efficiency of removal of fumigants from grains. Limits of quantification were < 0.2ng g-1 (ppb w/w) for each tested fumigant. The detection limit of COS was calculated, as natural levels of the fumigant were detected in commodities. These are feasible, simple and rapid (< 2 min.) to be use to analyse fumigant residue in grains. Carbonyl sulphide has potential as a fumigant for grain and timber and may replace methyl bromide in some uses, subject to further investigation in commercial situations.

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Martin-Lapierre, Andréanne. "Application de composts et de fumigants pour lutter contre la verticilliose (Verticillium dahliae) du fraisier." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28498/28498.pdf.

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Gurban, Ana-Maria. "Biosensors based on dehydrogenases for food and environmental monitoring." Perpignan, 2006. http://www.theses.fr/2006PERP0922.

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Les déshydrogénases NAD-dépendantes constituent une classe d’enzymes particulièrement attractives pour le dosage de nombreux substrats dans le domaine agro-alimentaire, et en particulier dans le secteur viti-vinicole. Cette thèse de doctorat décrit la mise au point de biocapteurs ampérométriques pour le contrôle de la fermentation malolactique du vin. Les différents capteurs développés sont basés sur des systèmes bi-enzymatiques couplant la malate déshydrogénase (MDH) à une NADH oxydase, ou sur des systèmes mono-enzymatiques associant la MDH ou une malate-quinone oxydoréductase (MQO) à des médiateurs électroniques judicieusement sélectionnés. Des capteurs utilisant une aldéhyde déshydrogénase ont été également décrits pour la détection de fongicides et fumigants de la famille chimique des dithiocarbamates
NAD-dependent dehydrogenases constitute a particularly attractive class of enzymes for the determination of various substrates in agrifood industry, and more specifically for wine industry. This thesis describes the development of amperometric biosensors for the monitoring of malo-lactic fermentation of wine. The different sensors designed are based either on bi-enzymatic systems coupling malate dehydrogenase (MDH) and NADH oxidase, or on mono-enzymatic systems associating MDH or a malate-quinone-oxidoreductase (MQO) with suitable electronic mediators. Sensors incorporating an aldehyde dehydrogenase are also described for the detection of dithiocarbamate fungicides and fumigants

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Ha, Wonsook. "Non-isothermal fate and transport of drip-applied fumigants in plastic-mulched soil beds model development and verification /." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0012921.

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Scurich, Justin J. "STRAWBERRY GROWTH, YIELD, FRUIT NUTRITION, AND CONTROL OF VERTICILLIUM WILT WITH PRE-PLANT SOIL FUMIGANTS, OZONE, AND BIOLOGICAL CONTROL." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/714.

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Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, chloropicrin, and 1, 3-Dichloropropene. Additional treatments included ozone gas (six treatments) and biological control (three treatments). Collected data included total plant yield, individual berry weight, number of fruit produced per plant, plant vegetative weight, infection status, and mineral concentration of fruit (calcium, magnesium, potassium, iron, zinc, manganese, carbon, and nitrogen). Plants grown in ‘clean’ soil were less likely than plants grown in ‘infested’ soil to be infected with Verticillium. Plants grown in soil treated with MB had higher plant weight and yield than did non-treated control. Ozone and biological control treatments did not have statistically higher yield than non-treated control plants nor statistically lower yield than plants grown in soil treated with MB. Individual berry weights had a narrow range while the number of berries produced per treatment had a wide range. Data suggests strawberry yield is dependent on the number of berries produced per plant. Plants with high vegetative weight produced the highest yield suggesting large plants produce many berries resulting in higher yield.

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Sekhon, Ramandeep Kaur. "EFFECTS OF VARIOUS FUMIGANTS AND ALTERNATIVE PROCESSING METHODS ON THE SAFETY, VOLATILE COMPOSITION, AND SENSORY QUALITY OF DRY CURED HAM." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11052009-143259/.

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Randomized complete block designs with three replications were utilized to evaluate the effects of fumigation with sulfuryl fluoride (SF) (0, 12, 24, 36 and 72 mg/L), phosphine (PH₃) (0, 200 and 1000 ppm at 48 hr), methyl bromide (MB) (0, 4, 8, 16, and 32 mg/L for 48 hr), carbon dioxide (CO₂) (0, 60% at 48 hr and 60% at 96 hr) and ozone (O₃) (0 ppm and 175 ppm for 48 hr) on the volatile flavor compound concentrations in dry cured ham. Fluoride and SF concentrations increased (P < 0.05) in dry cured hams as SF fumigation concentration increased, but all samples contained fluoride and SF concentrations below the legal limits of 20 and 0.01 ppm, respectively. Also, as phosphine fumigation concentration increased, the residual concentration of phosphine also increased in the hams (P < 0.05), but all samples contained levels that were lower than the legal limit of phosphine in stored food products (0.01 ppm). Minimal differences existed in the presence and concentration of aroma active compounds in fumigated hams when compared to the control. Triangle tests indicated that consumers could not discern (P > 0.75) between the control hams and the fumigated hams. This study revealed that there were minimal aroma/flavor differences among control hams and hams that were fumigated with SF, PH₃, MB, CO₂ or O₃ and that fumigation of dry cured ham with SF and PH₃ were safe and met legal requirements for consumption. This reveals that SF, PH₃, CO₂ and O₃ could be tested at the industrial level to determine their efficacy as potential alternatives to methyl bromide to treat dry cured hams for insect pests.

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Clark, L. J., and E. W. Carpenter. "The Effects of Methyl Bromide Fumigants on Verticillium Wilt on Two Varieties of Short Staple Cotton, Safford Agricultural Center, 1988." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/204842.

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Methyl bromid/chloropicrin formulations were applied to strips in the verticillium nursery at the Safford Agricultural Center where two varieties of short staple cotton were subsequently planted. More robust plant growth and reduced incidence of disease were noted with some of the treatments. Yield increases over the check plots were also seen. A study of the residual effects of the treatments will be performed in 1989.

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Ahmed, Qasim Hussein. "Evaluation of efficacy of fumigants and natural product extracts for management of springtail Hypogastrura vernalis (Collembola: Hypogastruridae) and green peach aphid Myzus persicae (Hemiptera: Aphididae)." Thesis, Ahmed, Qasim Hussein (2018) Evaluation of efficacy of fumigants and natural product extracts for management of springtail Hypogastrura vernalis (Collembola: Hypogastruridae) and green peach aphid Myzus persicae (Hemiptera: Aphididae). PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/46427/.

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Vegetables are one of the most important crops in the world and especially in Australia. Under this research, three study cases were investigated for controlling vegetable pests, purple scum springtail Hypogastrura vernalis in export celery and green peach aphid Myzus persicae in Brassica crops. They are a serious quarantine and production pests of economically important celery and crucifer crops and hence were selected for the current study. This research investigates and assesses the impact of the use of various fumigants on infested celery with H. vernalis along with the use of plant volatiles and natural plant-based essential oils for control of M. persicae. Celery bunches become host to the Australian native springtail (Hypogastrura vernalis) (Collembola: Hypogastruridae). Springtails live inside the celery bunch and do not cause damage to the product. Springtails are, however, considered a quarantine pest and have had a significant impact on celery exports. On the other side, using chemical pesticides against aphids has led to resistant aganist chemical pesticides so that require further experiments on the prospective role of factors affecting M. persicae pest status, including plant volatile compound and essential oils are urgently needed. Australia has widely grown celery Apium graveolens var. dulce for domestic and export markets. In the field, celery bunches become host to the Australian native springtail. These insects live inside the celery head, contaminating fresh celery but do not cause any visible damage. In chapter study, evaluation of ethyl formate (EF), phosphine (PH3) and their combination were used for celery fumigation against purple scum springtails that naturally infest celery. The selection of EF and PH3 was because both provide fast kill of insect within a few hours and are registered as fumigants in Australia. The material of EF breakdown is ethanol and formic acid, while the PH3 is slightly soluble in water and be broken down quickly into other products in the atmosphere. These are the first experiments that have used EF and PH3 for harvest celery fumigation. In the laboratory experiments, three concentrations of EF 50, 60 and 90 mg L-1; four concentrations of PH3 1, 1.5, 2 and 2.5 mg L-1 and three concentrations of EF 20, 30 and 40 mg L-1 combined with 1 mg L-1 of PH3 were used for various exposure times at the laboratory temperature 25˚C. The result indicated that 100% mortality was achieved at 90 mg L-1 of EF for 2 h and 100% mortality was also achieved at 30 and 40 mg L-1 EF combined with 1 mg L-1 of PH3 for 2 and 4 h exposure time, however, phytotoxicity was observed in celery treated with EF at all concentrations both in combination and alone. PH3 at 2.5 mg L-1 achieved 100% mortality within 6 h, and no phytotoxicity was evident. From these data, we conclude that PH3 alone has potential as a fumigant for the pre-shipment treatment of celery infested with purple scum springtails. In order to further develop natural or biological methods to manage the interaction between insect pests and host plants (three replicates per treatment) was studied using volatile organic compounds (VOCs). The VOCs from uninfested and infested Brassica plants with M. persicae were investigated by headspace solid microextraction (HS-SPME) combined with gas chromatography mass spectrometry (GC-MS). There is a need for chemical pesticides replacement with environmentally friendly alternatives because of chemical pesticides have been widely used against various pests including aphids have been shown a negative side of environments and an effect on non-target organisms and to understand the communication between aphid and the host plant. Understanding the biological and chemical basis of volatiles could lead to new approaches to the biocontrol of aphids. In Chapter two, the study was evaluated on VOCs from uninfested and infested Brassica plants with M. persicae. The results show that 29 compounds were detected in both infested and uninfested cabbage Brassica oleracea L. var. capitata, and 25 compounds were identified in both infested and uninfested broccoli Brassica oleracea L. var. italica plant samples. The HS-SPME combined with GC-MS analysis of the volatiles describes the differences between the infested and uninfested Cruciferous plant samples. Based on peak area from the GC-MS analysis, the VOCs from infested cabbage consisted of Propane, 2-methoxy, alpha- and beta-pinene, Myrcene, 1-Hexanone, 5-methyl-1-phenyl, Limonene, Decane, gamma-Terpinen and 2,4,4-trimethyl Heptane, all these volatiles were higher in the infested cabbage compared with their peak area in the uninfested cabbage. Similarly, the VOCs from infested broccoli were significantly greater than that from uninfested broccoli, such as D-limonene, Undecane, 3,4-dimethyl-, Heptane, alpha-Pinene, Oxalic acid, Citronellol, Tridecane, n-Decanoic acid, Cyclopentane, pentyl and n-Hexadecanoic acid compared with volatiles released from uninfested broccoli. The results presented in this chapter three outline the response of aphids and parasitoids to plant volatiles by using Y-tube olfactometer. The results show that M. persicae were significantly attracted to infested and uninfested cabbage and broccoli plants compared with clean air; the percentage of aphid choice was 80% and 70% toward infested cabbage and broccoli, respectively, and 7% and 10% were attracted to the clean air choice. While 75.5% and 84% of aphids attracted to uninfested plants comparison with clean air 3% and 7%, for the cabbage and broccoli, respectively. Comparing infested and uninfested plants, the aphids were attracted by 63% and 26.6% for infested cabbage and broccoli respectively, versus 57% and 30% for uninfested cabbage and broccoli, respectively. The results indicate that using an olfactometer, tested parasitoids prefer and are attracted to, the cabbage plants infested with M. persicae compared with clean air. Parasitoids can discriminate the infested plant and significantly responsed to the infested plant odour and attracted by 86.6% and 100% for both parasitoids toward infested Brassica plants. Another way to reduce chemical pesticides usage is with alternatives such as biopesticides for insect pest management. Therefore, chapter four describes the use of different essential oils (black pepper, eucalyptus, rosemary and tea tree), in combination and alone, against M. persicae. These essential oils have insecticidal activity and repellency against many insects including aphids and bioassay studies showed significant control of the green peach aphid through higher mortality. The results show that black pepper and tea tree pure essential oils were effective and caused 80% mortality of aphids for the contact treatment. However, the residual toxins were the most effective on aphids with 100% mortality for pure black pepper and tea tree oil and less than 96% for eucalyptus and rosemary. The combination of essential oils was tested with bioassay as contact and residual toxins. For the contact treatment, the mortality was 98.33% for black pepper + tea tree and rosemary + tea tree. While, in the residual treatment, the mortality was 100% for black pepper + eucalyptus, rosemary + eucalyptus and rosemary tea tree. The essential oil combinations exhibited synergistic, additive and antagonistic interactions for insecticidal activity. The combination of binary essential oils black pepper + tea tree oil showed enhanced activity, with a synergistic rate of 2.19. Essential oil formulation showed effective mortality of aphids, but phytotoxicity appeared on cabbage plants. The Fourier Transform Infrared Spectroscopy (FTIR) analysis of stability of a mixture of essential oils showed that it was not affected by store temperature (15, 25 and 35˚C) and all functional groups were not changed during the storage for three months. Based on the results, essential oils can be used as a commercial insecticide against M. persicae thereby reducing the use of chemical pesticides and their negative impact on the environment and human health. Natural products based on essential oils can be an excellent alternative to synthetic pesticides. In summary, the use of EF fumigant in combination with PH3 and alone achieved high mortality on purple scum springtails, however, phytotoxicity on treated celery is a negative. Alternatively, PH3 alone achieved 100% mortality after 6 h without any observed phytotoxicity, therefore, PH3 has potential as a fumigant for the pre-shipment treatment of celery infested with purple scum springtails. Plant volatile organic compounds that release from the infested cabbage and broccoli can use as an indicator tool for the field infestation related to the differences between the infested and uninfested plant. Base on Y-tube olfactometer, Myzus persicae response to both infested and uninfested plants and parasitoids response to the infested plants. From the laboratory experiments, essential oils show high mortality on green peach aphids and could be used as an alternative to chemical pesticides. According to the FTIR analysis, essential oils can be stored at between 15 and 35˚C with no effect on the properties of the oil. Therefore, I suggest that tested essential oil constituents both pure and in combination could be screened as a potential natural insecticides. Further they could be involved in the chemical synthesis of new types of pesticides, based on essential oils and their constituents.

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McAvoy, Theodore Porter. "Managing Weeds and Soilborne Pests with Fumigant and Non-Fumigant Alternatives to Methyl Bromide." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/37813.

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Methyl bromide (MBr) was widely used as a soil fumigant to manage soilborne pests in plasticulture vegetable production; however, it has been banned by the United Nations Environment Programme. Alternatives to MBr must be implemented to sustain fresh market tomato productivity. Possible MBr alternatives include new fumigant compounds, improved plastic mulch, and grafting. Methyl iodide (MeI) and dimethyl disulfide (DMDS) were tested as fumigant alternatives to MBr for the control of yellow nutsedge and soilborne pathogens of tomato. Virtually impermeable film (VIF) and totally impermeable film (TIF) were tested for fumigant retention and yellow nutsedge control in tomato. Grafting onto resistant rootstocks was tested for bacterial wilt and nematode management in tomato. In the absence of a soil fumigant, TIF suppressed yellow nutsedge better than VIF. TIF increased fumigant retention compared to VIF at similar application rates. Reduced fumigant application rates could be used in combination with TIF while maintaining fumigant concentrations, weed control, and crop yields comparable to greater use rates with VIF. Shank applied DMDS rates could be lowered to 281 L/ha under TIF from 468 L/ha under VIF; shank applied MeI application rates could be reduced to 56 L/ha under TIF compared to 93 L/ha under VIF and drip applied DMDS could be reduced from 561 L/ha under VIF film to 374 L/ha under TIF. Grafting susceptible commercial tomato cultivars onto resistant tomato hybrid rootstocks increased yields and plant survival in bacterial wilt infested fields. â Cheong Gangâ , â BHN 998â , and â BHN 1054â were the best performing rootstocks for bacterial wilt resistance and tomato fruit yield in severely infested fields. Grafting increased tomato yield and decreased root galling from root-knot nematodes in an infested field. Hybrid rootstock â RST 106â resulted in the lowest root-knot nematode galling. In conclusion, TIF with reduced rates of DMDS or MeI is a viable MBr alternative for fresh market tomato production to retain effective doses of fumigant, manage yellow nutsedge and maintain yields. Grafting is an effective MBr alternative to manage bacterial wilt and root-knot nematode and maintain tomato yields.
Ph. D.

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Rozado, Adriano Ferreira. "Ozônio como fumigante na proteção de milho armazenado." Universidade Federal de Viçosa, 2005. http://locus.ufv.br/handle/123456789/3642.

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The current work aimed to assess the susceptibility of adults of Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), subjected to ozone treatment at different depths in the grain mass, thus estimating the lethal time for 50% and 95% of each species population, and also assess the physiological quality of the maize grains subjected to the ozone treatment. Maize grains with moisture level around 13% (wb) were distributed in cylindrical PVC containers with 20 cm diameter, 100 cm high and connections for gas injection and exhaustion. At 10 cm from the base of the container, a metallic net was placed to sustain the grain and to form a plenum for better gas distribution. Maize grains infested with adults of Sitophilus zeamais and Tribolium castaneum, obtained from laboratory colonies from climatic chamber of the B.O.D. type, were placed in cages of 3.0 cm high and 15.0 cm diameter with top and bottom of voil to evaluate the efficiency of ozone as fumigant. These cages were placed at different grain mass depths (over the plenum, middle and top of grain column) and subjected to a modified atmosphere of 50 ppm ozone under different exposure periods. The ozone was injected in a continuous flow of 8.0 L min-1 in connection located at the base (plenum) of the container. Tests of electrical conductivity, germination potential and humidity level were carried out in the maize grains to assess the ozone effect on them. The grain mass temperature was maintained around 25 oC throughout the experiment. To do that, a temperature controlled chamber was built where the containers were placed. The temperature was monitored through a data acquisition and store system called f-wire. Six cylindrical containers were used in all of the assays and in three of these ozone was injected, while the remaining ones were injected with atmospheric air (control). It was concluded that in general the increase in exposure period increased the efficiency of the treatments with 50 ppm ozone for adults S. zeamais and T. castaneum. The species S. zeamais was more susceptible. The highest exposure period to control 95% of the insects was of 240.75 h for S. zeamais and 390.18 h for T. castaneum. The greatest exposure period to control 50% of the adult insects was 124.20 h for S. zeamais and 234.75 h for T. castaneum. In general, the treatments with modified atmosphere containing 50 ppm ozone and atmospheric air did not affect the physiological quality of the maize grains.
O presente trabalho teve por meta avaliar a suscetibilidade dos adultos de Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) e Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), submetidos ao tratamento com ozônio em diferentes camadas da massa de grãos, estimando-se, assim, os tempos letais (TL) para 50% e 95% da população de cada espécie e, ainda, avaliar a qualidade fisiológica dos grãos de milho submetidos aos tratamentos com ozônio. Grãos de milho com teor de umidade em torno de 13% (b.u.) foram distribuídos em recipientes cilíndricos, construídos em PVC, com 20 cm de diâmetro, 100 cm de altura e conexões para injeção e exaustão de gás. A 10 cm da base do recipiente, colocou-se uma tela metálica para sustentação dos grãos e formação de um plenum para melhor distribuição do gás. Para avaliar a eficácia do ozônio como fumigante, grãos de milho infestados com adultos de Sitophilus zeamais e Tribolium castaneum, obtidos de criação contínua em câmara climática do tipo B.O.D., foram distribuídos em gaiolas de 3,0 cm de altura e 15,0 cm de diâmetro, também em PVC, sendo o fundo e a tampa confeccionados em tecido do tipo organza. Estas gaiolas foram dispostas em diferentes camadas da massa de grãos (sobre o plenum, mediana e superior) e submetidas a uma atmosfera modificada com 50 ppm de ozônio em diferentes períodos de exposição. O ozônio foi injetado em fluxo contínuo de 8,0 L min-1, em conexão localizada na base (plenum) do recipiente. Para avaliar o efeito da fumigação com o ozônio na qualidade do milho, foram realizados testes de condutividade elétrica, potencial de germinação e teor de umidade. Em todo o experimento, a temperatura da massa de grãos foi mantida próxima de 25 oC. Para tanto, construiu-se uma câmara com controle de temperatura onde foram acondicionados os recipientes cilíndricos, sendo esta monitorada por meio de um sistema de aquisição e armazenamento de dados denominado 1-wire. Em todos os ensaios foram utilizados seis recipientes cilíndricos, sendo que em três destes injetou-se ozônio e nos outros foi injetado ar atmosférico (testemunha). Concluiu-se que, em geral, o aumento do período de exposição resultou no aumento da eficácia dos tratamentos com 50 ppm de ozônio para os adultos de S. zeamais e T. castaneum. A espécie que se mostrou mais susceptível foi S. zeamais. O maior período de exposição para o controle de 95% dos insetos foi de 240,75 h para o S. zeamais e de 390,18 h para o T. castaneum. O maior período de exposição para o controle de 50% dos insetos adultos foi de 124,20 h para o S. zeamais e de 234,75 h para o T. castaneum. Em geral, os tratamentos com atmosfera modificada com 50 ppm de ozônio e com ar atmosférico, não afetaram a qualidade fisiológica dos grãos de milho.

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Andrade, Nathália Curty. "Estudo proteômico da interação do Aspergillus fumigatus com células endoteliais da veia umbilical humana (HUVECs)." Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9181.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
O Aspergillus fumigatus é o principal agente etiológico da aspergilose invasiva, uma infecção fúngica oportunista que acomete, principalmente, pacientes de Unidades Hematológicas, como aqueles com neutropenia profunda e prolongada. Após a filamentação este fungo angioinvasivo é capaz de ativar e causar danos em células endoteliais de veia umbilical humana (HUVEC) que passam a expressar um fenótipo pró-trombótico. A ativação destas células, dependente de contato célulacélula, é mediada por TNF-α e caracterizada pela expressão de moléculas próinflamatórias, como citocinas, quimiocinas e moléculas de adesão. Recentemente, nosso grupo comparou a ativação endotelial de HUVECs desafiadas com cepas selvagens e uma cepa mutante para o gene UGM1. Nestes experimentos a cepa mutante Δugm1, que apresenta um fenótipo de maior produção de galactosaminogalactana (GAG) na parede celular, mostrou um fenótipo hiperadesivo e uma capacidade maior de ativar células endoteliais. Entretanto, os receptores e as vias de sinalização envolvidos nesta ativação permanecem desconhecidos. Assim, o objetivo deste trabalho foi verificar as proteínas envolvidas nestes processos através do estudo das proteínas diferencialmente expressas nas HUVECs após a interação com A. fumigatus, usando a técnica proteômica 2D-DIGE. Brevemente, as HUVECs foram infectadas com tubos germinativos da cepa selvagem (AF293) e da cepa Δugm1 de A. fumigatus. Em seguida, as proteínas foram marcadas com diferentes fluorocromos e separadas por eletroforese bidimensional. A análise quantitativa foi realizada utilizando o software DeCyder. Foram identificadas por MS/MS cinco proteínas diferencialmente expressas, incluindo a galectina-1 e a anexina A2, ambas mais expressas após a interação, sendo a primeira ~25% mais expressa após a interação com a mutante Δugm1. Este trabalho propõe que a galectina-1 poderia ser o receptor endotelial para polímeros de galactose presentes na parede celular do A. fumigatus, e que a Anexina A2 poderia estar envolvida na sinalização intracelular em resposta a este patógeno. No entanto, experimentos complementares, em curso, são necessários para comprovar esta hipótese.
Aspergillus fumigatus is the main etiological agent of invasive aspergillosis, the main opportunistic fungal infection of Hematologial Unitys patients, especially those with long-term neutropenia. Upon filamentation, this angioinvasive fungus can activate and damage the human umbilical vein endothelial cells (HUVEC), which in response switch to a pro-thrombotic phenotype. HUVEC activation is mediated by TNF-α once cell-cell contact occurs. This activation is characterized by the expression of pro-inflammatory molecules such cytokines, chemokines and adhesion molecules. Recently, our group performed the comparison of HUVEC activation upon interaction with a wild type and the UGM1 mutant strains of A. fumigatus. The Δugm1 strain, which presents an increased production of the cell wall galactosaminogalactan, showed a hyper adherent phenotype and an increased capability to cause endothelial cell stimulation and activation, when compared with the wild type strain. The receptors involved in the pathogen-host interaction or the signaling pathways after endothelial activation by A. fumigatus remain unknown. Thus, the aim of this study was to investigate the differentially expressed proteins in HUVECs upon interaction with A. fumigatus, using the 2D-DIGE proteomic approach. Briefly, HUVECs were challenged with germlings of A. fumigatus wild type Af293 and Δugm1 strains and then submitted to protein extraction. The total HUVEC protein extracts were labeled with different CyDyes and fractionated by 2D electrophoresis. Quantitative analysis to determine the differences in protein abundance amongst interacted cells vs. control endothelial cells was performed using the software DeCyder. Five differentially expressed proteins were identified by MS/MS including galectin-1 and annexin A2, both overexpressed after the interaction. These two proteins are described elsewhere to be associated with host-pathogen interaction. Besides, galectin-1 showed an ~25% increase after interaction with the Δugm1 strain and it is plausible that this particular protein could be a putative receptor for galactose-containing polymers of the A. fumigatus cell wall and annexin A2 could be involved in signalizing pathways upon interaction. However, other experimental evidences, under development, are necessary to confirm this hypothesis.

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Mat, Isa Zaiton. "Mathematical modelling of fumigant transport in stored grain." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/75420/1/Zaiton_Mat%20Isa_Thesis.pdf.

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Computational fluid dynamics, analytical solutions, and mathematical modelling approaches are used to gain insights into the distribution of fumigant gas within farm-scale, grain storage silos. Both fan-forced and tablet fumigation are considered in this work, which develops new models for use by researchers, primary producers and silo manufacturers to assist in the eradication grain storage pests.

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Weaver, Sean. "Heterokaryon incompatibility in Aspergillus fumigatus." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/heterokaryon-incompatibility-in-aspergillus-fumigatus(c0db26be-8326-4a93-8bcb-2648069e256c).html.

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Invasive aspergillosis (IA) is associated with high mortality rates and can be difficult and expensive to treat with current drugs. The drugs used to treat IA are also associated with undesirable, and often severe, side-effects of the patient. The main causative agent of this disease is the opportunistic pathogen Aspergillus fumigatus. This study identifies genes which play a role in a fungal-specific type of programmed cell death (PCD) in A. fumigatus, known as heterokaryon incompatibility. The development of drugs specifically targeting the products of these genes could lead to fewer side-effects than those arising from currently available anti-fungal drugs. The drug amphotericin B is currently used to treat IA and has been shown to induce an apoptotic-like phenotype in A. fumigatus; however, the sterols targeted are present in both fungal and mammalian cell membranes. HI is a fungal-specific self/non-self recognition system that results in rapid compartmentalisation and cell death of hyphal fusion sites if the two fusing fungi are not genetically compatible. The HI system could be exploited as a novel drug target against invasive fungal pathogens through targeting a component of the molecular pathway to induce cell death. In contrast to current drugs, novel drugs could target HI components to induce PCD without affecting non-desirable targets that cause side-effects. The non-self recognition systems used by Neurospora crassa, Aspergillus Nidulans and Podospora anserina are the well characterised, and they each differ significantly in their modes of action. BLAST searches found 30 homologues of HI genes from other the systems of characterised species in A. fumigatus, with 8 containing the fungal-specific het domain. The first assay to determine whether disruption of het genes could affect HI was to observe the barrage phenotype between incompatible A. fumigatus individuals. However, there was no barrage visible as the leading edge of colonies stopped growing when in close proximity to another colony. Instead, nitrate non-utilising (Nit) A. fumigatus mutant strains were generated using chlorate and pair-wise crosses of 46 environmentally and clinically isolates on nitrate-containing media resulted in the formation of 16 viable heterokaryons. All of the heterokaryons fell into exclusive compatibility groups where no intergroup crossing was possible. Homologous recombination was used to disrupt five of the identified het domain genes with gene replacement cassettes, generated through fusion-PCR, in an akuB(KU80Delta) A. fumigatus strain. The mutant strains displayed both detrimental growth on standard agar growth media and reduced ability to recognise non-self strains. Full and partial heterokaryons were formed during intergroup pair-wise compatibility crosses using the mutants and strains that the akuB(KU80Delta) parent strain was previously incompatible with. This was followed with a non-bias approach of gene disruption using the Fusarium oxysporum impala160 transposable element in a Nit A. fumigatus mutant. Inducing transposon mutagenesis through exposure to low temperature generated a mutant library of spores in which the transposon had disrupted different open reading frames at different locations across the A. fumigatus genome. The mutant spore library was also screened for the ability to form viable intergroup heterokaryons with strains belonging to different compatibility groups. PCR recovery and DNA sequencing was able to identify the locus of impala160 in three isolates able to form viable heterokaryons. The sequences revealed the transposable element had disrupted the same gene, AFUA_2G05070, in each of the three isolates. This gene encodes an uncharacterised conserved hypothetical protein which may be a critical component for non-self recognition in A. fumigatus HI, and a potential target for novel anti-fungal drugs to induce PCD.

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MOUTAOUAKIL, MOHAMMED. "Caracterisation des exoantigenes d'aspergillus fumigatus." Paris 7, 1992. http://www.theses.fr/1992PA077137.

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A. Fumigatus est un pathogene opportuniste qui est responsable de plusieurs types de mycoces: asthme allergique, aspergillose broncho-pulmonaire allergique, aspergillome et aspergillose invasive. Le diagnostic de l'aspergillose est base sur la detection soit d'anticorps circulants specifiques (igg ou/et ige en fonction de la maladie) soit d'antigenes circulants dans le cas de l'aspergillose invasive. A ce jour, moins d'une dizaine d'antigenes ont ete purifies. L'identification et la purification des antigenes est donc une des etapes essentielles a franchir en vue d'ameliorer les tests de detection deja existant ou de mettre au point de nouveaux tests originaux. Les antigenes secretes par a. Fumigatus sont identiques d'une souche a l'autre mais varient en fonction des conditions de culture. Ces antigenes ont des poids moleculaires apparents compris entre 10 et 205 kda. Quatre antigenes secretes par a. Fumigatus in vitro ont ete caracterises. L'antigene de 35 kda est reconnu de facon specifique par 55% des serums de patients. Sa purification reste difficile car cet antigene est present en tres faibles quantites dans le filtrat de culture. L'antigene de 18 kda a ete purifie a homogeneite. Cet antigene fait partie de la famille des ribotoxines capables de bloquer la synthese proteique. Cette proteine a ete detectee dans les urines de patients atteints d'aspergillose invasive et pourrait donc servir pour le developpement d'une nouvelle methode diagnostique. L'antigene de 33 kda est une serine protease purifiee a partir du filtrat de culture lorsque a. Fumigatus est cultive dans un milieu a base de collagene ou d'hydrolysats de proteines si le ph est maintenu entre 7 et 8. A cause de leur activite enzymatique et de leur presence in vivo, la proteine de 33 kda et la ribotoxine de 18 kda pourrait jouer un role dans la pathogenicite de ce champignon. L'antigene de 94 kda a ete purifie a partir du filtrat de culture d'a. Fumigatus produit dans un milieu contenant exclusivement de l'extrait de levure. Les souris ayant survecu a une infection aspergillaire ont des anticorps diriges de facon quasi exclusive contre cet antigene de 94 kda, ce qui suggere un role protecteur de ces anticorps contre l'infection par a. Fumigatus. Enfin la comparaison des antigenes produits par a. Fumigatus in vitro et in vivo dans les poumons de souris infectees a permis l'identification d'un grand nombre d'antigenes dont deux seulement avec des poids moleculaires de 20 et 38 kda semblent specifiquement produits in vivo

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15

Robertson, Maura Diane. "Host defences against Aspergillus fumigatus." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/26892.

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The potential of the filamentous fungus Aspergillus fumigatus to act as an opportunistic pathogen may be related to its ability to resist the host defence network. Whilst phagocytic cells are clearly important in host defences against invading microorganisms their precise role in the killing of A. fumigatus remains undefined. The purpose of this study was to examine the basic interactions between phagocytic cells, from humans and rodents, with spores of A. fumigatus. In particular the mechanisms whereby phagocytic cells bind and kill spores of A. fumigatus, when compared with the relatively non-pathogenic fungus Penicillium ochrochloron were investigated. In order to investigate why people with asthma may develop some hypersensitivity reactions to A. fumigatus, in particular, rather than to the many other fungi in the atmosphere, the possibility that there may be a defect in the handling of the fungus by such patients has been tested. A comparison of the fungal handling by phagocytes from asthmatic patients, both sensitised and unsensitised to A. fumigatus with phagocytes from non-asthmatic subjects has been made. The principal findings from this study are that spores of A. fumigatus bind to the surface of the phagocytic cell yet are relatively resistant to phagocytosis. The spores also fail to trigger the phagocytic cells into releasing the potentially microbicidal reactive oxygen intermediates. These results may be related to a further finding which is that spores of A. fumigatus release a low molecular weight substance (diffusate) which interferes with various aspects of phagocytic cell activation. Spore diffusates were shown to inhibit the phagocytosis of radiolabelled antibody-coated sheep red blood cells and to suppress the spontaneous release of reactive oxygen intermediates by Corynebacterium parvum stimulated mouse peritoneal exudate cells. In addition spores diffusates inhibited the ability of phagocytic cells to spread on glass and reduce the number of phagocytic cells migrating towards a known chemoattractant. Studies on spore killing showed that spores of A. fumigatus opsonised in autologous serum were more resistant to killing by phagocytic cells from humans and rodents than similarly opsonised spores of P. ochrochloron. However, the ability of the phagocytic cells to kill spores of A. fumigatus was substantially increased when the spores were opsonised in sera which had been heat-treated for 30 minutes at 56?C. No increased killing was found with P. ochrochloron. People with asthma sensitised to A. fumigatus showed significant differences in their handling of A. fumigatus in vitro when compared with the control group. Monocytes from these sensitised patients killed significantly fewer spores of A. fumigatus (opsonised in auto? logous sera) whilst their polymorphonuclear leucocytes killed significantly more. No such differences were found for P. ochrochloron. The work reported in this Thesis has given us a clearer understanding of why Aspergillus fumigatus is an important cause of disease in man, and how the defence mechanisms that it has evolved in its natural environment the soil, enable it to act as a saprophyte or parasite in the lungs of humans and animals. The results also suggest a mechanism whereby heat-labile serum components may be an advantage to the survival of the fungus, thus perhaps explaining why it may be a particular problem in the airways of asthmatic patients.

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Melloul, Elise. "Aspergillose aviaire : développement d’un modèle d’aspergillose chez la dinde (Meleagris gallopavo) et évaluation de l’efficacité de l’énilconazole." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1183/document.

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Aspergillus fumigatus est un agent pathogène respiratoire majeur chez les oiseaux d’ornement comme de production. L’aspergillose qui peut être responsable de mortalités importantes et de chutes de performances est difficile à traiter. Nous avons développé un modèle d’aspergillose aiguë chez le dindonneau en inoculant différents lots d’oiseaux âgés de moins d’une semaine via une aérosolisation intratrachéale de doses croissantes de conidies (105 à 108/animal) en utilisant un MicroSprayer®. Le développement de la masse fongique a été évalué par qPCR, dosage du galactomannane (GM), culture fongique et évaluation histopathologique dans le but de comparer les résultats obtenus en fonction du nombre de conidies inoculées. Une mortalité significative a été observée dans les 4 jours suivant l’inoculation uniquement pour l’inoculum le plus concentré. Les résultats des différents marqueurs du développement du champignon (culture, qPCR et GM), sont très bien corrélés avec la dose de l’inoculum administrée. Les moyennes d’équivalents conidies/g de poumon obtenues par qPCR étaient 1,3 log10 plus importantes que les numérations obtenues par culture sur gélose. Ce nouveau modèle incluant une combinaison inédite de biomarqueurs chez la dinde a été utilisé pour évaluer l’efficacité de l’énilconazole, seule molécule utilisée en élevage avicole pour lutter contre l’aspergillose
Aspergillus fumigatus remains a major respiratory pathogen in both ornamental and poultry. Aspergillosis can be responsible for high mortality rates and induces significant economic losses, particularly in turkey production, and it is still difficult to treat. We developed a new model of acute aspergillosis in young turkeys by inoculating few-days-old turkeys via intratracheal aerosolization with increasing concentrations (105 up to 108) of conidia using a MicroSprayer® device. The fungal burden was assessed and compared by real-time PCR, galactomannan (GM) dosage, fungal colony (CFU) counting and by histopathology. Early death occurred in the first 96 h post-inoculation only at the highest inoculum dose. We observed a correlation between inoculum size and results obtained by real-time PCR, GM dosage and CFU counting. The mean fungal burden detected by qPCR was 1.3 log10 units higher than the mean values obtained by CFU measurement. Furthermore, this new model, with its unique combination of markers, has been used to evaluate the efficacy of enilconazole

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17

Bernard-Cardona, Muriel. "Protéines et paroi chez Aspergillus fumigatus." Phd thesis, INAPG (AgroParisTech), 2003. http://tel.archives-ouvertes.fr/tel-00005702.

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La paroi du champignon filamenteux A. fumigalus conditionne la croissance et est responsable du maintien de l'intégrité cellulaire lors de l'infection. Les protéines de la paroi de ce champignon filamenteux n'avaient pas été étudiées jusqu'à présent alors qu'elles semblent jouer un rôle essentiel dans la structuration de la paroi de la levure modèle S. cereviciae. Une approche essentiellement biochimique a permis de caractériser les protéines associées à la paroi de A..fumigatus. La majorité des protéines pariétales chez A. fumigatus sont des protéines solubles. Une seule protéine est relarguée à partir de la paroi par un traitement f3- (1 .3) glucanase : c'est une phosphatase acide qui possède une ancre GPl et dont l'expression est réprimée en présence de phosphate inorganique. Par ailleurs, une étude des protéines GPl chez A. fumigatus par génomique comparative a montré que les protéines GPI décrites comme associées de façon covalente à la paroi chez la levure n'ont pas d'homologue chez A. fumigatus. Ainsi. l'organisation des protéines au sein de la paroi de A..fumigatus est différente de celle de la levure : les protéines pariétales ne semblent pas avoir un rôle essentiel dans l'élaboration de la paroi. Ensuite, une nouvelle famille de glycoprotéines portant un N-glycane lié à un galactofuranose en position terminale a été décrite. Cette famille comprend une phospholipase C, une phosphatase alcaline et une phytase. Enfin, une analyse morphologique de deux mutants chitine synthase et gluconosyltransférase a permis d'associer la réduction de la croissance à un hyper-branchement du mycélium et à une diminution de la taille de la cellule apicale sans que l'organisation globale des polysaccharides pariétaux et le taux de croissance spécifique soient affectés.

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18

Brown, Jeremy Stuart. "Signature tagged-mutagenesis of aspergillus fumigatus." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322287.

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19

Kong, Yun-cheung, and 江潤祥. "Multilocus sequence typing of aspergillus fumigatus." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B4593972X.

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20

Marsh, Rachael. "Cytochrome P450 studies in Aspergillus fumigatus." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364267.

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21

Rosa, Carla Maria de Gouveia. "Detecção de Aspergillus fumigatus em Hemoculturas." Master's thesis, Faculdade de Farmácia da Universidade do Porto, 2007. http://hdl.handle.net/10216/9491.

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22

SPENTCHIAN, MARC. "Interaction aspergillus fumigatus - laminine : etude preliminaire." Nantes, 1990. http://www.theses.fr/1990NANT016M.

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23

Rosa, Carla Maria de Gouveia. "Detecção de Aspergillus fumigatus em Hemoculturas." Dissertação, Faculdade de Farmácia da Universidade do Porto, 2007. http://hdl.handle.net/10216/9491.

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24

Neves, Gabriela Westerlund Peixoto. "Perfil de secreção de citocinas e de ativação de células endoteliais após interação com cepas selvagens e mutantes de Aspergillus fumigatus." Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9177.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Apesar do desenvolvimento de novas drogas antifúngicas e da sua utilização como terapia profilática visando à prevenção de infecções fúngicas invasivas, estas ainda constituem-se num problema emergente, com elevadas taxas de mortalidade. Neste contexto, destaca-se a aspergilose invasiva, uma infecção fúngica oportunista que acomete pacientes com neutropenia profunda e prolongada, principalmente os pacientes com leucemia aguda ou submetidos a transplante de medula óssea. Aspergillus fumigatus, um fungo filamentoso, é o principal agente etiológico da aspergilose invasiva, sendo um patógeno angioinvasivo. As hifas deste fungo são capazes de causar injúria e ativação endotelial, induzindo o endotélio a um fenótipo pró-trombótico, que por sua vez, é mediado pela secreção de citocinas pró-inflamatórias, em especial, o TNF-α. O presente trabalho teve como objetivo estudar a capacidade de cepas mutantes de A. fumigatus em ativar células endoteliais, avaliando o perfil de secreção de citocinas em meio condicionado e a expressão de fator tecidual. Resumidamente, monocamadas confluentes de células endoteliais isoladas da veia umbilical humana foram incubadas com conídios e tubos germinativos de cepas selvagens (Af293 e Ku80) e mutantes (Δugm1, ΔcalA, ΔcrzA, ΔprtT) de A. fumigatus. A taxa de adesão e endocitose destas cepas às monocamadas de HUVEC foi avaliada a partir de um ensaio quantitativo de imunofluorescência diferencial. O perfil cinético de secreção de citocinas foi determinado em meio condicionado das HUVECs, por ensaio de multiplex para IL-6, IL-8 e TNF-α. A ativação endotelial, por sua vez, foi determinada pela expressão de fator tecidual por RT-PCR em tempo real. Os resultados obtidos demonstraram que a mutante para o gene ugm1, responsável por codificar a enzima UDP-galactopiranose mutase, que converte resíduos de galactopiranose a galactofuranose, apresentou um fenótipo hiperaderente às células endoteliais e um estímulo 10 vezes maior à secreção de TNF-α e 2,5 vezes maior a secreção de IL-6, quando comparada a ativação observada para as cepas selvagens. A galactofuranose é um componente importante de glicoconjugados da parede celular de A. fumigatus. Dessa forma, a ausência desse monossacarídeo na célula fúngica leva a um mecanismo compensatório caracterizado por um aumento na expressão de moléculas de galactosaminogalactana na parede celular. De maneira contrária, mutantes para os genes calA e crzA, apresentaram um fenótipo hipoaderente às HUVECs e uma perda na capacidade de induzir a secreção de citocinas e ativar o endotélio. Essas mutantes apresentam deleções que interferem na via de cálcio/calcineurina, responsável por regular a morfogênese e virulência de A. fumigatus, além de apresentarem alterações no conteúdo de beta-1-3 glucana. Já a cepa ΔprtT, mutante para o fator de transcrição prtT que regula a secreção de múltiplas proteases, apresentou um fenótipo de adesão, estímulo e ativação endotelial semelhante ao observado para as cepas selvagens. A comparação entre a capacidade de conídios e tubos germinativos em ativar células endoteliais, corroborou achados anteriores da literatura que reportam que só hifas são capazes de ativar células endoteliais, independentemente da sua viabilidade. Os dados deste estudo permitiram concluir que dentre os componentes de superfície celular de A. fumigatus, os polímeros de galactose, em especial a galactosaminogalactana, parecem ser responsáveis, pelo menos em parte, pelos mecanismos de interação e ativação endotelial.
Besides the emergency of more active and less toxic antifungal agents and the conventional use of antifungal prophylaxis, invasive mold infections have still high mortality rates, especially, invasive aspergillosis (IA). This life-threatening disease is a predominant fungal opportunistic infection for patients with long-term neutropenia, mostly HSCT recipients. Aspergillus fumigatus is the most important species causing IA and is already known as an angioinvasive fungal pathogen. Upon filamentation this fungus can damage and activate human vein endothelial cells (HUVEC) which in turn switch to a pro-thrombotic phenotype. HUVEC activation is known to be mediated by TNF-α once cell-cell contact occurs. The aim of this study was to investigate the endothelial activation ability of several mutants of A. fumigatus. Briefly, HUVECs were infected with germ tubes and conidia of A. fumigatus wild type (WT) Af293 and Ku80 and mutant (Δugm1, ΔcalA, ΔcrzA, ΔprtT) strains and a differential quantitative fluorescence assay performed to determine adhesion and internalization rates. Thus, a kinetic study of secreted pro-inflammatory cytokines and chemokines in HUVEC conditioned medium was achieved by a multiplex immuneassay. The cytokine production was assayed at three time points (4, 8 and 16 hours) using dead germ tubes, and at one time point (16 hours) using dead conidia, for an E:T ratio of 2:1. Additionally, to investigate endothelial activated phenotype, the expression of tissue factor was performed by a real time RT-PCR assay. The ugm1 mutant, which lacks the ugm1 gene encoding UDP-galactopyranose mutase, an enzyme responsible for the conversion of galactopyranose in galactofuranose, showed a hiperadherent phenotype and an increased capability to cause endothelial cell stimulation and activation. This mutant stimulated at least a 10-fold and 2.5-fold increase of TNF-alfa and IL-6 secretion, respectively and 2-fold increase of tissue factor expression by host cells, as compared to WT strains. Galactofuranose is an uncommon 5-membered ring form of galactose and a very important component of glycostructures of the A. fumigatus cell wall. The lack of this monosaccharide in the fungal cell wall leads to a compensatory mechanism characterized by an increment in the galactosaminogalactan expression. In contrast, the calA and crzA mutants, with upstream and downstream dysfunction in the calcium/calcineurin pathway, with alteration in the cell wall β-1,3-glucan content, showed a decrease capacity to adhere to HUVECs and did not induce both the secretion of pró-inflammatory cytokine and activation on endothelial cells. Furthermore, the mutant ΔprtT, witch lacks the transcriptional factor (prtT) that regulates the secretion of multiple proteases, showed the same adhesion and endothelial cell activation phenotype as observed for WT strains. As indicated in previous investigations, our data showed that conidia of A. fumigatus werent able to cause the same endothelial cell cytokine stimulation observed for germ tubes, and that endothelial cell activation is independent on fungal cell viability. Finally, its possible to conclude that the polymers of galactose in the cell wall of A. fumigatus, especially the galactosaminogalactan molecule, seem to be responsible for the endothelial cell interaction mechanisms and activation.

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Haddad, Ziad. "Monozytäre Zellantwort gegen Aspergillus fumigatus Untersuchung der Phagozytose, Genexpression und Peptidpräsentation = Monocytic cell responses to Aspergillus fumigatus /." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980508169.

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Urb, Mirjam. "Mechanisms of «Aspergillus fumigatus» chronic airway disease." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110500.

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Colonization of airways by Aspergillus fumigatus hyphae in immunocompetent patients with chronic lung disease leads to progressive decline in pulmonary function. While a minority of these patients develop a severe allergic response to the fungus, the majority of patients show a decline in lung function and airway hyperreactivity despite the absence of elevated IgE levels, eosinophilia or other evidence of hypersensitivity. Treatment of these non-allergic patients with antifungal drugs improves the symptoms, suggesting that pulmonary complications might be directly caused by A. fumigatus. The mechanisms underlying the acquisition of A. fumigatus colonization and the pathogenesis of pulmonary inflammation have not been studied. Our central hypothesis is that A. fumigatus interacts directly with elements of the immune system to facilitate its own colonization and induces ineffective inflammatory responses that damage host airways. To begin to investigate this hypothesis we used two complementary approaches to examine the interactions of A. fumigatus with elements of the pulmonary immune system. First, we studied the in vitro interactions of A. fumigatus with mast cells, key effector cells involved in orchestrating inflammatory responses and airway reactivity. We found that A. fumigatus triggers mast cell degranulation, while suppressing cytokine expression in an IgE-independent manner. While both degranulation and cytokine transcription required direct contact with mature hyphae, cytokine suppression could also be induced in part by A. fumigatus culture supernatant. Further studies revealed that A. fumigatus hyphae modulated mast cell function by downregulating protein tyrosine phosphorylation and in part by cleavage-dependent activation of protein tyrosine phosphatase 1B (PTP1B). The cleavage of PTP1B was caused by A. fumigatus serine proteases. In parallel, we developed a murine model of A. fumigatus colonization, where airways of healthy mice were colonized with live A. fumigatus by intratracheal injection of conidia embedded within agar beads. Unlike previously described models that induce airway hyperreactivity by repeated challenge with antigen or A. fumigatus spores, infection with this approach resulted in chronic colonization with fungi for up to 28 days. Fungal lesions within the airways were surrounded by a robust neutrophilic inflammation and peribronchial infiltration of lymphocytes. During the first 2 weeks of infection, low level Th2 type responses were seen in the infection, including increased pulmonary IL-4 levels, elevated serum IgE, and a mild increase in airway responsiveness. In addition, significant levels of pro-inflammatory cytokines and chemokines including TNF-α and MIG were observed, suggesting a mixed inflammatory picture. Furthermore, elevated IL-17 levels and presence of RORγ-positive mononuclear cells during late phase of the infection indicated the development of a Th17 response in association with reduction in pulmonary fungal load. Collectively, these results provide insight into the pathogenesis of A. fumigatus-induced chronic airways disease in patients without allergic bronchopulmonary aspergillosis, and suggest a possible role for mast cells in the pathogenesis of this condition.
La colonisation des voies respiratoires par les hyphes d'Aspergillus fumigatus chez des patients immunocompétents, mais avec une maladie pulmonaire chronique, entraîne le déclin progressif de la fonction des poumons. Alors qu'une minorité de ces patients développe une réponse allergique aigue au champignon, la majorité montre un déclin dans la fonction des poumons et une hyperréactivité des voies respiratoires malgré l'absence d'une augmentation du niveau des IgE, des éosinophiles ou d'autres indications d'hyper-sensibilité. Le traitement antifongique chez ces patients améliore les symptômes suggérant que le champignon peut être la cause directe des complications observées. Les mécanismes qui sous-tendent la colonisation par A. fumigatus et la pathogenèse de l'inflammation des voies respiratoires restent largement indéterminés. Notre hypothèse centrale stipule que le champignon interagit directement avec des éléments du système immunitaire pour faciliter la colonisation et induire une réponse inflammatoire inefficace qui cause des dégâts aux voies respiratoires de l'hôte. Pour vérifier cette hypothèse, nous avons développé deux approches complémentaires visant à tester l'interaction d'A. fumigatus avec des éléments du système immunitaire pulmonaire. D'abord, nous avons étudié l'interaction in vitro entre A. fumigatus avec les mastocytes, une population clé de cellules impliquées dans la réponse inflammatoire. Nous avons montré que le champignon déclenche la dégranulation des ces cellules, tout en bloquant l'expression des cytokines indépendamment des IgE. Les processus de dégranulation et de transcription des cytokines nécessitent un contact direct avec les hyphes matures, alors que la suppression des cytokines quant à elle peut être induite en partie par le surnageant de culture d'A. fumigatus. Une étude plus approfondie nous a permis de montrer que les hyphes d'A. fumigatus peuvent moduler la fonction des mastocytes via une régulation négative de la phosphorylation d'une protéine tyrosine kinase et, en partie, via l'activation clivage-dépendante de la protéine tyrosine phosphatase 1B (PTP1B). Ce clivage de PTP1B est causé par la serine protéase du champignon. Dans une seconde approche, nous avons développé un modèle murin pour la colonisation par A. fumigatus, où nous avons fait coloniser les voies respiratoires de souris saines avec le champignon par injection intra-trachéale de conidies encapsulées dans des billes en agar. Ce modèle, au contraire des précédents, qui induisent l'hyperréactivité des voies respiratoires par exposition répétée à un antigène ou des spores de A. fumigatus, permet une colonisation chronique par le champignon allant jusqu'à 28 jours. Après ce traitement, les lésions des voies respiratoires, causées par le champignon, se retrouvent entourées par une inflammation neutrophilique robuste ainsi qu'une infiltration péri-bronchiale des lymphocytes. Durant les deux premières semaines qui suivent l'infection, nous avons détecté des niveaux bas d'une réponse type Th2, y compris une augmentation des niveaux des IL-4 pulmonaires, élévation des IgE dans le sérum, et une augmentation légère de la réponse des voies respiratoires. En plus, une augmentation significative des cytokines et des chémokines pro-inflammatoires, y compris les TNF-α et MIG, a été observée suggérant une réponse inflammatoire mixte. Les niveaux élevés des IL-7 et la présence des cellules mononucléaires RORγ-positives durant la phase tardive de l'infection indiquent le développement d'une réponse de type Th-17 associée à une réduction de la charge fongique pulmonaire. Collectivement, ces résultats nous permettent de mieux comprendre le processus de pathogenèse lié aux maladies chroniques des voies respiratoires induites par A. fumigatus chez les patients sans aspergillose bronchopulmonaire allergique, et suggèrent que les mastocytes peuvent jouer un rôle dans cette pathogenèse.

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Leslie, Carolyn Elizabeth. "Studies on clinical isolates of Aspergillus Fumigatus." Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1653.

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Baillie, George Scott. "Characterisation of cytochromes P450 from Aspergillus fumigatus." Thesis, University of Kent, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334500.

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Taib, Mariam. "The complex chitinolytic system of 'Aspergillus fumigatus'." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416841.

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30

Rajendran, Ranjith. "Adaptive resistance mechanisms of Aspergillus fumigatus biofilms." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4333/.

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Biofilm formation is one of several significant virulence factors associated with life threatening pulmonary infections in immunocompromised individuals caused by Aspergillus fumigatus. Previous studies have demonstrated phase dependant antifungal activity against A. fumigatus biofilms. Antifungal resistance associated with fungal biofilms is a complex multifactorial phenomenon, and it remains unclear specifically how this manifests itself in A. fumigatus. This study therefore aimed to investigate adaptive resistance mechanisms in A. fumigatus biofilms. Different phases of A. fumigatus biofilms were grown for 8, 12, 24 and 48h in polystyrene plates in RPMI media. Functional efflux pump activity was subsequently assessed using an Ala-Nap fluorescent uptake assay. Extracellular material was extracted from each phase and the level of extracellular DNA (eDNA) was quantifiedusing a microplate fluorescence assay. The minimum inhibitory concentrations (MIC) of different classes of antifungals were assessed in the presence and absence of different inhibitors using a checkerboard assay, or with a fixed concentration, by the broth microdilution method to assess synergism, antagonism, or otherwise. The presence of eDNA and phenotypic changes in biofilm caused by antifungal agents and inhibitors were assessed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. The resultant biofilm biomass for different experiments was evaluated using a crystal violet assay. SYBR green qRT-PCR was used to assess the expression of different genes implicated in biofilm resistance (AfuMDR 1-4, ChiA-E, HSP90 and Fks1) over the period of multicellular development, using a diffusion chamber in a murine model and a Galleria mellonella infection model. The results from this study demonstrated phase dependant expression of efflux pumps in A. fumigatus biofilm populations, which actively contributes to azole resistance. Moreover, voriconazole treatment induced efflux pump expression in both in vitro and in vivo models.These data suggest that A. fumigatus efflux pump proteins, which evolved to become integral to their natural physiological function, have inadvertently induced resistance to azole drugs, albeit in the early phases of biofilm development. Assessment of A. fumigatus biofilm extracellular matrix (ECM), associated with maturing biofilms, showed that eDNA is an important architectural component of the biofilm, helping to maintain its stability. The antifungal sensitivity of different phases of A. fumigatus growth decreased significantly in the presence of DNase, indicating that decreased susceptibility to antifungals in the A. fumigatus is mediated in part by eDNA.Its release was shown to correlate withchitinase activity, a marker of autolysis, suggestive that autolysis was associated with eDNA release. It was hypothesised that heat shock protein 90 (HSP90) was involved in this autolytic pathway. Therefore, when HSP90 was pharmacologically inhibited this led to a decrease in matrix eDNA level, providing a compelling mechanism through which HSP90 might regulate biofilm antifungal resistance. To test whether these mechanisms of adaptive resistance had any bearing clinically, a G. mellonella model was developed. It was shown that each of the key genes were expressed during infection, both in control and antifungal treated larvae. This validates the potential use of this insect model for resistance and virulence studies. Overall, this study establishes several novel adaptive resistance mechanisms regulating biofilm drug resistance in A. fumigatus biofilms. Moreover, it highlights the potential to target these mechanisms as a therapeutic strategy for managing and improving clinical outcomes in these hard-to-treat infections.

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Pillé, Ariane. "Amyloïdes fonctionnelles du pathogène opportuniste Aspergillus fumigatus." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066696/document.

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Les hydrophobines sont des protéines fongiques caractérisées par leurs propriétés amphipathiques et un motif de quatre ponts disulfures. Leur forme soluble s’auto-assemble aux interfaces hydrophobe/hydrophile pour former une couche amphipatique. Ces protéines sont utilisées par les champignons pour franchir la barrière air/eau, former des hyphes aériennes ou recouvrir les spores les rendant hydrophobes, ce qui facilite leur dispersion dans l’air. L’hydrophobine RodA du pathogène opportuniste Aspergillus fumigatus forme une couche de fibres amyloïdes avec une morphologie en bâtonnets qui recouvre la surface des spores ce qui les rend inertes vis-à-vis du système immunitaire. Nous aspirons à décrire l’auto-association de RodA en bâtonnets, caractériser la structure des fibres et établir les potentiels liens entre structure et inertie immunologique. La protéine recombinante RodA exprimée chez E. coli peut être correctement repliée in vitro et s’auto-associe sous forme de fibres amyloïdes. Comme première étape, la structure et la dynamique de RodA ont été étudiées par RMN en solution. Par rapport aux autres hydrophobines, RodA présente de nouveaux éléments structuraux ainsi que d’autres conservés. Grâce à une étude de mutagénèse, des régions importantes dans la formation des fibres ont été identifiées, certaines impliquées dans le cœur des fibres et d’autres dans les interactions latérales des bâtonnets. Les relations entre la structure et les propriétés immunologiques ont également été établies. L’étude d’autres hydrophobines d’A. fumigatus, probablement impliquées dans la formation du biofilm ou importantes pour la conidiation et la survie des spores, a été initiée.dC), a été initiée
Hydrophobins are fungal proteins characterised by their amphipatic properties and a pattern of four disulfide bridges. Their soluble form self-assembles at hydrophobic/hydrophilic interfaces to form an amphipatic layer. These proteins are used by fungi to breach the air/water barrier, to form aerial hyphae, or to cover spores rendering them hydrophobic, thus facilitating spore dispersal. The RodA hydrophobin of the opportunistic pathogen Aspergillus fumigatus forms an amyloid monolayer with a rodlet morphology that covers the surface of spores rendering them inert relative to the immune system. We aim at describing the self-association of RodA into rodlets, characterising the structure of the amyloid rodlets and shedding light on the possible relationships between structure and immunological inertness. Recombinant RodA expressed in Escherichia coli can be successfully refolded in vitro and it can auto-associate into amyloid rodlets. As a first step, we have studied the structure and dynamics of RodA by solution NMR and shown that the protein displays new as well as conserved structural features relative to other hydrophobins. A mutational analysis has highlighted important residues for rodlet formation that may be involved on the one hand in the spine of the amyloid fibres and on the other hand on the lateral association of the rodlets to form a monolayer. We have also established the relationship between structure and immunological inertness. We have initiated the study of other hydrophobins from A. fumigatus, that are most likely involved in biofilm formation or in conidiation and spore survival

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Fillaux, Judith Sophie. "Évaluation de la sensibilisation à Aspergillus fumigatus et du portage persistant comme facteurs de détérioration de la fonction respiratoire des patients atteints de mucoviscidose au CHU de Toulouse." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2323/.

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Aspergillus fumigatus (Af) est responsable de maladies respiratoires. La mucoviscidose est une maladie génétique fréquente, à transmission autosomique récessive au cours de laquelle les manifestations respiratoires déterminent le pronostic de la maladie. Les publications sur les infections fongiques au cours de la mucoviscidose sont rares. Au CHU de Toulouse, deux CRCM, pédiatrique et adulte, suivent les patients de la région Midi-Pyrénées. Les médecins implémentent à chaque consultation un dossier informatisé. A partir de ces données, une étude a été menée afin de déterminer si le fait de présenter des signes directs et/ou indirects de la présence d'Af, en l'absence d'ABPA, pouvait être responsable de l'altération de la fonction pulmonaire. Dans un deuxième temps, après avoir identifié deux nouvelles entités morbides, la sensibilisation à Af et le portage persistant de ce champignon, un algorithme de calcul de risque a été proposé
Aspergillus fumigatus (Af) is a ubiquitous fungus that causes a wide range of pulmonary diseases. Cystic fibrosis (CF) is one of the most common life-shortening autosomal recessive diseases in which chronic endobrochial infection contributes to progressive obstructive pulmonary disease. The literature provides scarce information about the impact of fungal infection on the pulmonary function of CF patients. At the Toulouse CF Resources and Competence Centre, details of patients with CF are entered into a database during each visit. From these data, a study was conducted to assess Af related-status modulating the forced expiratory volume in one second of CF patients. We have determined that Af may be of clinical relevance in some CF patients who do exhibit manifestations of sensitisation or persistent carriage. Secondly, we assess the putative predictive factors for CF patients to become either sensitised to or carriers of Af, and we proposed a tree diagram for risk calculation

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Luther, Kathrin. "Interaktionen des humanpathogenen Schimmelpilzes Aspergillus fumigatus mit Wirtszellen." Diss., kostenfrei, 2007. http://edoc.ub.uni-muenchen.de/7678/.

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Amaar, Yousef Grera. "Molecular characterizations of nitrate assimilation in Aspergillus fumigatus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24287.pdf.

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Fraczek, Marcin Grzegorz. "The molecular analysis of allergens in Aspergillus fumigatus." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508896.

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Albarrag, Ahmed. "Azole resistance in clinical isolates of Aspergillus fumigatus." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487927.

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Aspergillus fil1nigatus is the most common aetiological agent of aspergillosis. Invasive aspergillosis is a major cause of death in leukaemic and organ transplant patients. The azoles are the largest and the most widely used class of antifungals. Antifungal drug resistance has been observed in many fungi. In many organisms, acquiring resistance to a drug can confer a biological fitness cost that is expressed for example as decreased growth rate or virulence. A total number of 21 A. fill11igatus clinical isolates were used in this project. Sixteen of these isolates were recovered serially from four patients at different times during the treatment period with azoles, including three cases of acquired azole resistance. The antifungal susceptibilities of isolates were determined. The genetic relatedness of the isolates was confirmed by microsatellite length polymorphism typing. Various measures of fitness were used to determine variation between susceptible and resistant isolates. Growth rate (colony radial growth rate and specific growth rate), germination time and conidial yields were determined on various media. Although some resistant isolates had a reduced growth rate compared to their susceptible match, there was no clear evidence of fitness cost of resistance has been found. The mechanisms of drug resistance in these isolates were investigated. Sequencing of the cyp5JA gene was carried out. Novel and previously described mutations in cyp5JA were identified. Three new mutations were detected in isolates recovered from patient D which were shown to have the same genotype. These mutations were G138C (in six isolates), Y431C (in one isolate) and G434C (in one isolate). These isolates have decreased susceptibility to itraconazole (>8.0 mg/l), voriconazole (4-8.0 mg/l), ravuconazole (4-8.0 mg/l), and posaconazole 0-4.0 mg/l). Azole cross-resistance observed in these isolates was confirmed to be caused by two of these mutations, G138C and Y431C, by expression of the mutated cyp5JA alleles in the yeast S. cerevisiae. The relative levels of expression of cyp5JA, cyp5JB and five efflux transporters, AfuMDRJ, AfilMDR2, AfiIMDR3, AfuMDR4 and atrF, genes were analysed using real-time RT-PCR. Gene expression analysis revealed that isolates from patient D had their cyp5JA gene up-regulated by 7.2- to 13.4-fold. Generally, susceptible and resistant isolates had the same level of expression of all five efflux transporters examined. Interestingly, a type II transposon insertion (1882 bp) in the region upstream of the start codon of cyp5JA, at position -317, was detected in one isolate from patient D, which exhibited the highest level of cyp5JA expression and so transposon insertion was associated with elevation of cyp5JA expression. In conclusion, this thesis describes novel mutations in the cyp5JA gene of clinical isolates that confer and azole cross-resistance. It also identified up-regulation of the cyp5JA gene as an additional azole resistance mechanism in some isolates. An active transposon was identified and found to be associated with resistance by elevating gene expression, an observation not previously made in A. fill11igatus for any phenotype. Up-regulation of 5 transporters and mutations in the cyp5JB gene were not related to resistance.

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Mowat, Eilidh. "In vitro modelling of chronic Aspergillus fumigatus infections." Thesis, Glasgow Caledonian University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501309.

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Recent studies have demonstrated the potential of Aspergillus fumigatus to form biofilm structures similar to those identified with Candida albicans. In contrast to the wide berth of knowledge relating to the biology of C. albicans biofilms, relatively little is known regarding the development and morphology of multicellular communities of A. fumigatus. This alternate lifestyle may have profound clinical implications with regard to the pathogenic potential of the organism and the likelihood of successful detection and treatment. A reproducible biofilm model of A. fumigatus was developed using several different substrates, which were used to macroscopically and microscopically investigate the phenotypic attributes and general characteristics of biofilm formation, and to investigate antifungal susceptibility profiles.

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Júnior, André Oliveira Mota. "Caracterização molecular do gene ncsA de Aspergillus fumigatus." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/17/17136/tde-05012009-123104/.

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O foco do trabalho está direcionado para a construção da linhagem knock-out do gene ncsA de A. fumigatus, bem como a caracterização do fenótipo da linhagem DncsA e a investigação de interações deste gene com vias de sinalização importantes para o desenvolvimento do fungo. A linhagem mutante ncsA foi construída através da transformação do WT (Dku80) com o gene marcador pyrG de A. fumigatus. Foi confirmada a deleção por Southern blot e as alterações fenotípicas da linhagem foram analisadas. O gene ncsA em A. fumigatus não é essencial e a linhagem DncsA apresentou-se sensível EGTA e SDS, alé, de tolerante a altas concentrações de íons cálcio. Na linhagem NcsA:mRFP foi localizado a proteína NcsA no citoplasma das células e sua localização não é alterada pela em resposta ao aumento da concentração de cálcio. A linhagem DncsA foi sensível a drogas que afetam a biossíntese e a manutenção da membrana plasmática, tais como voriconazole, anfotericina e itraconazole. O crescimento polarizado em presença de lovastatina nessa linhagem foi consideravelmente mais afetado que no tipo selvagem. O Spitzenkörper não foi visualizado no mutante DncsA, e existe uma significante diminuição de estruturas vacuolares e endossomos. Os resultados obtidos em ensaios de TRPCR em tempo real sugerem que NcsA modula a expressão dos genes pmcA e pmcB, que codificam proteínas ATPases transportadoras de íons cálcio. Os ensaios de virulência no modelo animal revelaram que a mutação do gene ncsA não causa perda de virulência no A. fumigatus.
Here, we characterize the A. fumigatus Neuronal Calcium Sensor, ncsA homologue. We showed that ncsA is not an essential gene and ncsA growth was decreased in the presence of EGTA and SDS. Furthermore, the ncsA mutant is more resistant to calcium chloride. NcsA:mRFP localizes to the cytoplasm that its cellular localization is not affected by the cellular response to calcium chloride. The ncsA mutant strain is more sensitive to voriconazole, itraconazole, and the ergosterol intercalating agent, amphotericin. Polar growth in the DncsA mutant strain was also considerably more affected by lovastatin than in the wild type mutant strain. The Spitzenkörper cannot be visualized in the DncsA mutant, and there is a significant decrease of the endosome/vacuole structures. NcsA supports pmcA and pmcB expression therefore reduced expression of these ion pumps, and also of other genes involved in the response to calcium in A. fumigatus. The ncsA inactivation mutation is not causing loss of virulence in a low dose murine infection when compared to the corresponding wild type strain.

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Hündling, Dörte. "Caractérisation biochimique et structurale de lectines d'Aspergillus fumigatus." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV055/document.

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L'objectif de cette thèse a été de contribuer à la compréhension des stratégies d'infection du pathogène opportuniste Aspergillus fumigatus. Ce pathogène est une cause émergente de morbidité et de mortalité chez les patients dont l'immunité est compromise et dans les milieux hospitaliers. Une infection avec Aspergillus est en général appelée une Aspergillose et ellepeut se développer dans un certain nombre d'organes, le plus fréquemment dansl'appareil respiratoire (poumons et sinus). Outre les infections (Aspergillosis invasive), la colonisation par ce champignon peut causer des réactions allergiques (Aspergilloses broncho pulmonaire allergique) et de l'asthme. Le nombre de patients immunodéprimés augmente régulièrement à cause des avancées des traitements du SIDA, du cancer, de la mucoviscidose ainsi que par le nombre grandissant de transplantation d'organes. De nouveaux médicaments antifongiques et des médicaments préventifs sont nécessaires pour venir en soutienaux soins médicaux des patients. Bien que plusieurs fongicides existent déjà sur le marché, l'Aspergillosisinvasive reste souvent fatale. Ceci est lié d'une part à la difficulté d'établir le diagnostic, et d'autre part au fait que des résistances émergent rapidement. La motivation de cette thèse est de comprendre les mécanismes impliqués dans le premier contact entre les conidies et le tissu de l'hôte. Ces mécanismes d'adhésion initiaux sont souvent réalisés par des liaisons entre les lectines et les carbohydrates. Le tissu épithélial et la surface muqueuse du système respiratoire sont couverts de structures possédants des carbohydratestels que les glycoprotéines, les glycolipides et les glycosaminoglycanes. L'identification des lectines d'A. fumigatus et leurs caractérisations devraient dorénavant contribuer à la compréhension de la glycostratégie de ce pathogène opportuniste ainsi que des mécanismes impliqués dans l'adhésion et l'infection. L'analyse détaillée de la structure des lectines permettra d'établir le rôle de cesprotéinesdans la virulence et de guider la conception de glycomimétiques, afin d'inhiber le phénomène d'adhésion. Cettenouvelle approche consistant à bloquer l'adhésion de l'agent pathogène plutôt que sa prolifération, vise à diminuer les résistances par une réduction de la pression évolutive. Deuxstratégies différentes ont été utilisées pouridentifier de nouvelleslectines. Tout d'abord une purification des lectinesà partir d'extraits fongiques brutsa été tentée et d'autre part un criblage pour trouver des séquences similaires avec les protéines codées par A. fumigatusa été réalisé parmi une banque de lectines fongiques connues
The aim of this thesis was to contribute to the understanding of infection strategies of the opportunistic pathogen Aspergillusfumigatus. This pathogenic mould is an emerging cause of morbidity and mortality in immuno-compromised patients and hospital environments. An infection with Aspergillus is generally referred to as Aspergillosis; it can develop in a variety of organs but the most common sites are the respiratory apparatus i.e. lungs and sinuses. Besides infections (invasive aspergillosis), colonization with the fungus can cause allergic reactions (allergic broncho pulmonary aspergillosis) and asthma. The number of immuno-suppressed patients is steadily increasing due to advancement in the HIV, cancer and cystic fibrosis medical care, as well as an increasing number of organ transplantations. Needless to say that new antifungal drugs and preventive medication is desperately needed to support medical care for those patients. Even though several fungicides already exist on the market, invasive aspergillosis remains to be often fatal. On one hand, this is due to difficulties in diagnosis and on the other hand, resistances are emerging rapidly. The motivation behind this thesis is to understand the underlying mechanisms that are involved in the first contact between conidial spores and host tissues. Initial adhesion steps often involve carbohydrate binding proteins, called lectins. They recognize glycoconjugates such as glycoproteins, glycolipids and glycosaminoglycans which cover the epithelial tissue and mucosal surface of the respiratory tract.. Identification and characterization of the lectins from A. fumigatus will therefore contribute to the understanding of the glycostrategy of this opportunistic pathogen and of the mechanisms involved in adhesion and infection. Detailed structural analysis of the carbohydrate-protein interactions will allow ascertaining the lectins role in virulence and guide the design of glycomimetics, as adhesion inhibitors. With this novel approach of targeting the pathogen adhesion rather than its proliferation, resistances are believed to be less frequent due to the lack of evolutionary pressure. In this work, two different strategies were employed to obtain novel lectins. Firstly, lectins were purified from crude fungal extracts and secondly the A. fumigatus genome was screened for encoded proteins showing sequence similarity with known fungal lectins. While lectin purification from the crude extracts was inconclusive due to low lectin activity in the starting material, genome screening showed that several putative lectins were present. One of these lectins, named AFL6, belonged to the cyanovirin-N homolog (CVNH) family and it was recombinantly expressed and purified. Glycan array and micro calorimetry techniques were carried out to investigate its carbohydrate binding specificityand the three dimensional structure was determined using X-ray crystallography. The structure showed an overall similarity with other CVNHs with slight differences in the presumed carbohydrate binding sites. Unlike other family members, it shows a low affinity for mannosides and an apparent affinity for lactosamine containing glycan structures

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40

Jamal, Atif. "Incidence and characterisation of mycoviruses from Aspergillus fumigatus." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6092.

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This study investigated the incidence and characterisation of mycoviruses in a range of different fungi including Phytophthora spp. Phlebiopsis gigantea and Aspergillus fumigatus and their effects on their hosts. The investigation developed methodology for rapid molecular characterisation of dsRNA elements from different fungi which were applied in detail to a range of isolates of A. fumigatus. DsRNA elements or mycoviruses are present in almost all major classes of fungi where they lack an extracellular phase and are transmitted intracellulary via anastomosis or spores. Mycoviruses can confer a range of phenotypes on their fungal hosts ranging from symptomless to debilitating and hypovirulence to hypervirulence. In most cases most fungal mycovirus infections are symptomless and the effects of A. fumigatus mycoviruses on fitness and growth of infected isolates were also investigated. A screen of thirty nine clinical isolates of A. fumigatus, which is an opportunistic human pathogen and causes aspergillosis in immunocompromised patients, revealed the presence of dsRNA elements which were hitherto unknown. Two mycoviruses were identified including a chrysovirus (isolate A-56) and an unclassified, triripartite dsRNA-containing mycovirus (isolate A-54). All four dsRNA segments of the A-56 chrysovirus were sequenced in their entirety using the methodologies developed earlier in the investigation and the sequences analysed and compared to other members of the family Chrysoviridae and other characterised mycovirus families. Also the effects of the chrysovirus on the fitness of the host fungus were studied as was transfer of the purified chrysovirus to cured strains of A. fumigatus via protoplast fusion and direct transfection by different methods. It is intended to develop the use of dsRNA elements for gene silencing in A. fumigatus and towards this aim a full-length clone of the smallest A-56 dsRNA has been constructed and characterised and used to produce dsRNA transcripts for infection and amplification in the fungus.

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Griffiths, James. "CLRs and their role during Aspergillus fumigatus infection." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/114588/.

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CLRs are vital for orchestrating anti-fungal immunity. These receptors are expressed on myeloid immune cells and induce robust anti-A.f. responses including phagocytosis, cytokine and chemokine release, respiratory burst, and inflammasome activation. The role of Dectin-1 has been thoroughly investigated; however, the CLRs requirement during anti-A.f. response is controversial. The impact of Dectin-2, Mcl and Mincle during anti-A.f. immunity is not well understood. A.f. is complex and poses many challenges for the immune system. PRR collaboration is likely required for A.f. clearance. Collaboration between TLRs and CLRs has been identified. Recently, the first CLR:CLR collaboration was demonstrated between Dectin-1 and Dectin-2; however, this was not in response to A.f. The research in this thesis describes many novel interactions between CLRs and A.f. and seeks to further the understanding of the complex collaborative anti-A.f. immune response. Firstly, a novel role for NE inducing Dectin-1 Isoform A cleavage was described. This impaired A.f. recognition and the anti-A.f. response. CF patients possess high airway NE activity and experience a severe A.f. disease burden. My research suggests blocking the action of NE in CF patient’s airway may restore Dectin-1 expression and improve patient’s anti-A.f. immune response. Secondly, in vivo CLR KO and DKO models were used to elicit alveolar macrophages reliance on CLRs when generating anti-A.f. responses. My research suggests Dectin-1 might exclusively be required during early anti-A.f. responses. Unfortunately, discrepancies between the sex and microbiome of mice restricted the conclusions drawn from in vivo CLR KO and DKO A.f. infection experiments. Finally, I identified novel risk factors that can be used to stratify patients according to their susceptibility to A.f. infection. A.f. disease incidence and mortality rates are unacceptably high in immune-suppressed patients. Patients are often prophylactically treated with inadequate anti-fungal therapeutics. Stratifying patients according to their A.f. disease susceptibility would allow a personalised medicine approach and reduce unnecessary treatment.

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Cardoso, Fernanda Gomes. "Vias alternativas mitocondriais: estudos moleculares e bioquímicos de uma UCP-like de Aspergillus fumigatus." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/17/17131/tde-08012016-124834/.

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A. fumigatus é um patógeno oportunista que causa infecções invasivas em hospedeiros imunocomprometidos. Estudos de respiração mitocondrial sugeriram a presença de componentes alternativos em sua cadeia respiratória envolvidos com processos de adaptação a ambientes adversos, como a proteína desacopladora (UCP). UCPs são proteínas mitocondriais cuja atividade dissipa o potencial de membrana gerado durante o transporte de elétrons. Um gene contendo características das três assinaturas moleculares das Proteínas Transferidoras de Energia foi clonado e sequenciado. O alinhamento das sequências genômica e de cDNA mostrou a presença de dois íntrons que, após o splicing, codifica uma proteína contendo 341 aminoácidos, com uma massa molecular de 37 kDa e um pI de 10,02. A fim de se avaliar as propriedades bioenergéticas da UCP-like, essa sequência foi clonada no vetor pYES2 e leveduras S. cerevisiae foram transformadas. Esferoplastos foram preparados e o potencial elétrico transmembrana mitocondrial foi estimado. Os resultados mostraram que o potencial de membrana de esferoplastos de leveduras expressando a proteína UCP-like foi ligeiramente menor e que o decréscimo momentâneo do potencial associado com a fosforilação do ADP foi mais lento quando comparado com o controle, indicando desacoplamento da respiração. Além disso, esse comportamento dos esferoplastos recombinantes foi similar ao controle quando GDP foi adicionado ao meio de reação, sugerindo uma inibição da proteína por esse composto. Para sua caracterização funcional em sistemas reconstituídos, a sequência foi clonada no vetor pET SUMO. A expressão foi realizada em E. coli e a proteína recombinante, purificada por cromatografia em resina de níquel, foi analisada por Western blot com anticorpos anti-(His)6-tag e anti-UCP2 e por espectrometria de massas. A formação dos lipossomos foi confirmada através de medidas de distribuição de partícula por espalhamento de luz dinâmico, as quais sugeriram a formação de vesículas estáveis. Em adição, foi investigada a participação da UCP-like na proteção do A. fumigatus contra danos oxidativos. O nível de mRNA foi determinado por PCR em tempo real na presença de paraquat e menadiona. Em A. fumigatus, a presença dessas drogas pró-oxidantes resultou em um aumento no nível de mRNA desse gene, sugerindo que essa proteína possa também fazer parte de um sistema de defesa antioxidante do fungo.
A. fumigatus is an opportunistic pathogen that causes invasive infections in immunocompromised hosts. Mitochondrial respiration studies suggested the presence of alternative components on its respiration chain, which are involved with the adaptation to hostile environments, such as the uncoupling protein (UCP). UCPs are mitochondrial proteins whose activity dissipates the membrane potential generated during electron transport. A gene containing features of three molecular signatures of Energy Carrier Protein was cloned and sequenced. The alignment between the cDNA and genomic DNA sequences revealed the existence of two introns which after splicing encodes a 341 amino acids protein with a molecular mass of 37 kDa and a pI of 10.02. In order to study bioenergetics properties of UCP-like, the cDNA sequence was cloned into pYES2 vector and transformed in S. cerevisiae. Spheroplasts were prepared and the mitochondrial electrical transmembrane potential was estimated. The results showed that, compared with control cells, mitochondrial electrical transmembrane potential of transformant spheroplasts was slightly smaller and the transient potential decrease associated with ADP phosphorylation was longer, indicating uncoupling of respiration. Moreover, this behavior of recombinant spheroplasts was similar to control cells when GDP was added to the reaction medium, suggesting the inhibition of uncoupling protein. For its functional characterization in reconstituted systems, the cDNA sequence was cloned into pET SUMO vector. The expression was carried out in E. coli and the recombinant protein, purified by chromatography on a nickel-chelating resin, was analyzed by Western blot using anti- (His)6-tag or UCP2 antibodies and by mass spectrometry. Liposome formation was confirmed by light scattering, suggesting the formation of stable vesicles. In addition, the participation of UCP-like in A. fumigatus protection against oxidative damage was investigated. mRNA level was determined by real time PCR in the presence of paraquat and menadione. In A. fumigatus, the presence of these pro-oxidants drugs resulted in increased mRNA level of this gene, suggesting that this protein might also be part of an antioxidant defense system of this fungus.

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Fischer, Sandra Elena. "Vergleich von konventionellen PCR Methoden mit den Aspergillus fumigatus spezifischen Primern TS2 und AfLC2 und dem Panfungal-Primer für die Aspergillus fumigatus Diagnostik bei Risikopatienten." [S.l. : s.n.], 2007.

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44

Larsen, Jean. "Farmworkers and Strawberry Cultivation in Oxnard, California: A Political Economy Approach." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/scripps_theses/502.

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I argue that although the abusive conditions experienced by farmworkers have complicated causes, they have persisted and will continue to persist as long as farmworkers are stripped of virtually any political and economic power. The chapters build upon each other logically, beginning with the second chapter, which uses farmworker testimony to establish that a combination of economic and political circumstances have kept farmworkers from protesting not only methyl bromide, but every other dangerous condition they face in the fields. In the third chapter, I argue that despite commonly held assumptions, growers are virtually powerless to change the circumstances of farm workers because competition they face in the strawberry market precludes any single grower from paying their workers more than the going rate. I will conclude by arguing that to begin to improve the working conditions of farm workers, consumers will need to engage with the issue on both political and economic levels. The conclusion builds on the arguments established in the second and third chapters; namely, given that neither growers nor farmworkers will be able to leverage change within the current political and economic context, consumers are the only remaining actors with both the incentives and power to influence both the political and economic arenas. Just as scholarship that focuses on only one set of actors (i.e. only growers or only regulators) will necessarily fail to provide practical solutions because such papers tend to discount the pressures faced by and produced by other actors, so too will change be impossible without consumers who advocate that farmworkers both receive a just share of political voice and fair wages.

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Massango, Handina da Graça Lurdes Langa. "Atividade fumigante do óleo essencial de salsa sobre Callosobruchus maculatus em feijão-caupi." Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/8239.

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O feijão-caupi, Vigna unguiculata, (L.), Walp. é uma leguminosa de ampla distribuição mundial, encontrada principalmente nas regiões tropicais. Os grãos de feijão-caupi apresentam problemas sérios de perdas pós-colheita, grande parte ocorrendo em razão do armazenamento inadequado e do ataque por insetos-praga, destacando-se o Callosobruchus maculatus (Coleoptera: Bruchidae). O controle de C. maculatus em feijão-caupi armazenado é feito principalmente com o fumigante fosfina, no entanto, o uso em longo prazo de um único inseticida aumenta o risco do crescimento de populações resistentes. Como alternativa, tem sido pesquisado o uso de inseticidas de origem vegetal que têm relativa toxicidade a diversas espécies de insetos. Este trabalho foi conduzido com o objetivo de avaliar a atividade fumigante do óleo essencial de salsa, Petroselinum sativum, (Mill.) Fuss, sobre C. maculatus, em feijão-caupi. A toxicidade do óleo essencial e do gás fosfina (controle positivo) foi avaliada para estimar as concentrações letais de 50 e 95% (CL 50 e CL 95 ). As unidades experimentais foram constituídas por frascos de vidro com 0,8 L de capacidade, contendo 100 g de feijão-caupi e 20 insetos adultos com idade de 1 a 3 dias. O óleo essencial foi aplicado em recortes de papel colocados dentro de sachês de organza e colados nas tampas dos frascos. A toxicidade foi avaliada 48 h após a exposição dos insetos ao óleo essencial e à fosfina. A taxa instantânea de crescimento populacional dos insetos na presença do óleo essencial e da fosfina foi determinada utilizando as concentrações letais CL 10 , CL 30 , CL 50 , CL 70 e CL 90 obtidas nos bioensaios de toxicidade. O experimento foi montado no delineamento inteiramente casualizado com 5 repetições. A progênie adulta foi contabilizada após 45 dias. Os resultados da toxicidade indicaram CL 50 de 489,5 μL L -1 e CL 95 de 635,8 μL L -1 para o óleo essencial de salsa e CL 50 de 35,7 μL L -1 e CL 95 de 68,5 μL L -1 para a fosfina. Verificou-se que o óleo essencial de salsa apresenta efeito inseticida fumigante no controle de adultos de C. Maculatus e depende da concentração aplicada. Além disso, a perda de massa do feijão-caupi tratado com óleo essencial de salsa e com o gás fosfina foi menor em relação ao controle negativo (sem tratamento), indicando que a exposição dos insetos ao óleo essencial e ao gás fosfina reduziu o número de insetos de C. maculatus. O poder germinativo dos grãos de feijão- caupi foi diretamente proporcional às concentrações do óleo essencial e do gás fosfina.
Cowpea, Vigna unguiculata (L.) Walp. is a legume of worldwide distribution, mainly found in tropical regions. The cowpea grains has serious problems of post-harvest losses, largely occurring due to improper storage and attack by insect pests, highlighting the Callosobruchus maculatus (Coleoptera: Bruchidae). The control of C. maculatus in stored cowpea is done primarily with the phosphine fumigation, however, the long term use of a single insecticide increases the risk of resistant populations development. Alternatively, it has been investigated the use of insecticides of plant origin that have relative toxicity to various insect species. This work was carried out to evaluate the fumigant activity of the essential oil of parsley, Petroselinum sativum (Mill.) Fuss, on C. maculatus in cowpea. Toxicity of essential oil and phosphine gas (positive control) was evaluated to estimate the lethal concentrations of 50 and 95% (LC 50 and LC 95 ). The experimental units consisted of glass bottles with 0.8 liter capacity containing 100 g of cowpea and 20 adult insects aged 1-3 days. The essential oil was applied to paper cutouts placed inside organza sachets and glued to the bottle caps. Toxicity was assessed 48 h after exposure of the insects to the essential oil and phosphine. The instantaneous rate of growth of the insects in presence of the essential oil and phosphine gas was determined using lethal concentration LC 10 , LC 30 , LC 50 , LC 70 and LC 90 obtained in bioassays of toxicity. The experiment was conducted in a completely randomized design with 5 repetitions. The adult progeny was recorded after 45 days. The results of toxicity indicated 489.5 μL -1 to LC 50 and 635.8 μL -1 to LC 95 for essential oil of parsley and 35.7 μL -1 to LC 50 and 68.5 μL -1 to LC 95 for phosphine. It was found that the essential oil of parsley has a fumigant insecticidal effect in controlling adults of C. maculatus which effectiveness depends on the applied concentration. Moreover, the weight loss of the cowpea treated with essential oil of parsley and with phosphine gas was lower compared to the negative control (no treatment), indicating that exposure of the insects to the essential oil and phosphine gas reduced the number of C. maculatus. The germination of cowpea grain was directly proportional to the concentrations of the essential oil and phosphine gas.

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Soriani, Frederico Marianetti. "Caracterização de uma cálcio ATPase PMR1 de \'Aspergillus fumigatus\'." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/60/60135/tde-02102008-163023/.

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Os conhecimentos sobre a regulação dos níveis de cálcio e manganês no Aspergillus fumigatus são bastante limitados, sendo que a homeostase destes íons pode ser diretamente controlada pela ação de ATPases específicas, dentre elas as cálcio ATPases da subfamília PMR1. Desta forma, o objetivo do presente estudo foi a expressão, caracterização e validação como alvo quimioterapêutico do gene Afpmr1 de A. fumigatus. Inicialmente, foi realizada a complementação funcional, de uma cepa de S. cerevisiae nocaute para a PMR1, em meios de cultura suplementados com EGTA ou manganês, revertendo o fenótipo da cepa nocute. Além disto, após expressão do gene Afpmr1, foi verificada uma reversão na intensa distribuição de quitina na parede celular da cepa nocaute. Paralelamente, para a RNAi, um fragmento do gene Afpmr1 apresentando baixa identidade com outros genes de cálcio ATPases de diferentes espécies foi clonado em vetor de expressão em A. fumigatus (pALB1). Após indução da expressão, a construção de RNA dupla fita para RNAi silenciou tanto o gene alb1 isoladamente (clone controle), quanto o duplo silenciamento com o gene de interesse Afpmr1, conferindo à ambas construções coloração branca às colônias. Uma vez confirmado o silenciamento gênico, por técnicas de RT-PCR quantitativo, os clones selecionados foram utilizados em ensaios de fagocitose e killing de macrófagos. O clone com o gene Afpmr1 silenciado apresentou diminuição na porcentagem de fagocitose, no número médio de conídios fagocitados e na eficiência de eliminação destes conídios quando comparados com seus controles. Estes resultados mostram que o gene Afpmr1 pode ser expresso funcionalmente em sistemas heterólogos e seu silenciamento, em A. fumigatus, influencia processos celulares que podem estar relacionados à manutenção da estrutura e composição da parede celular, além de desencadear alterações na fagocitose e killing de macrófagos.
The knowledge about the regulation of Aspergillus fumigatus calcium and manganese levels are very limited, while these ions homeostasis could be directly controlled by the function of specific ATPases, like the PMR1 calcium ATPase. In this way, the aim of the present work was the expression, characterization e validation, as chemotherapeutic target, of the A. fumigatus Afpmr1 gene. Initially, the functional complementation of a PMR1 knock-out strain phenotype was analyzed in EGTA or manganese supplemented culture media. Besides, after Afpmr1 expression, an intense distribution of chitin through the cell wall of the knock-out strain was reversed. At the same time, a fragment of the Afpmr1 gene, showing low identity values for another calcium ATPase genes, was cloned in an A. fumigatus expression vector (pALB1) for RNAi. After the induction of gene expression, a double strand RNA construct for RNAi has properly silenced either the alb1 gene alone (control clone), or the double silencing with the gene of interest Afpmr1, leading to both constructions white colored colonies. After confirmation of the gene silencing by quantitative RT-PCR techniques, the selected clones were used in macrophages killing and phagocytosis assays. The Afpmr1 silenced clone showed a decrease in the phagocytosis percentage, in the mean number of internalized conidia and in the killing percentage when compared with control groups. These results show that the Afpmr1 gene can be functionally expressed in eukaryotic heterologous systems and its silencing, in A. fumigatus, alters cellular processes that can be related with the maintenance of the cell wall structure and composition, as well as promote alterations in the macrophages phagocytosis and killing.

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Vieira, Fabíola Giovanna Nesello. "Otimização da produção de β-xilosidase por Aspergillus fumigatus." Universidade Estadual do Oeste do Parana, 2014. http://tede.unioeste.br:8080/tede/handle/tede/187.

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The abundant lignocellulosic biomass in agro-industrial waste can be reused as an inexpensive substrate for inducing the production of enzymes such as β-xylosidases. The purpose of this study was to analyze the production of β-xylosidase from Aspergillus fumigatus (PC-7S-2 M), isolated from the Atlantic Forest of the Dog Head State Park (Paraná, Brazil) and later identified by morphological and molecular (ITS) methods. The mesophilic fungus was grown at 28 °C in liquid culture media containing Czapeck and 1% of different agroindustrial residues (w/v): passion fruit peel, Ponkan peel, barley brewing residue, soy flakes and ripe banana peel. Inoculants of 105 conidia ml-1 were incubated for 7 days, filtered and assayed for β-xylosidase intracellular activity obtaining a maximum value of 15 U ml-1 of the enzyme in the presence of barley brewing residue after 4 days of cultivation. Then, it was used a Central Composite Rotational Design (CCRD) to optimize the production of β-xylosidase, using barley brewing residue as carbon source at a significance level of p<0.10 which generated a predicted model of 245.04 U ml-1. Model validation provided an average optimized result equal to 229.06 U ml-1 for the enzyme. Thus, the production of β-xylosidase increased in 1,500% over the initially obtained for A. fumigatus in the presence of the barley brewing residue, therefore, achieving 93.47% of the predicted model. This finding emphasizes the availability of A. fumigatus β-xylosidase production with possible applications in several biotechnological process.
A biomassa lignocelulósica abundante nos resíduos agroindustriais, pode ser reutilizada como substrato barato para induzir a produção de enzimas, como β-Xilosidases. O objetivo deste trabalho foi analisar a produção de β-Xilosidase de Aspergillus fumigatus (PC-7S-2 M), isolado da Mata Atlântica do Parque Estadual Cabeça do Cachorro (Paraná, Brasil) e posteriormente identificado por métodos morfológicos e moleculares (ITS). O fungo mesofílico foi cultivado à temperatura de 28 °C em meios líquidos de cultura Czapeck, contendo 1% de diferentes resíduos agroindustriais (w/v): casca de maracujá, casca de pokan, bagaço de cevada, flocos de soja e casca de banana madura. Inóculos de 105 conídios mL-1 foram incubados durante 7 dias, filtrados e submetidos a dosagem de β-Xilosidase intracelular, obtendo-se um valor máximo de 15 U ml-1 para a enzima na presença de bagaço de cevada com 4 dias de cultivo. Assim, utilizou-se um delineamento composto central rotacional (DCCR) para otimizar a produção de -Xilosidase, usando o bagaço de cevada como fonte de carbono em um nível de significância p < 0,10, o qual gerou um modelo predito de 245,04 U ml-1. A validação do modelo forneceu um resultado otimizado médio igual a 229,06 U ml-1 para a enzima. Assim, a produção de β-Xilosidase aumentou em 1.500% em relação à obtida inicialmente para o fungo A. fumigatus na presença de bagaço de cevada como fonte de carbono (15 U ml-1), permitindo, deste modo, alcançar 93,47 % do modelo predito. Este achado ressalta a viabilidade de produção de β-Xilosidase de A. fumigatus com possíveis aplicações em vários processos biotecnológicos.

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48

Vieira, Fabíola Giovanna Nesello. "Otimização da produção de β-xilosidase por Aspergillus fumigatus." Universidade Estadual do Oeste do Parana, 2014. http://tede.unioeste.br:8080/tede/handle/tede/2646.

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The abundant lignocellulosic biomass in agro-industrial waste can be reused as an inexpensive substrate for inducing the production of enzymes such as β-xylosidases. The purpose of this study was to analyze the production of β-xylosidase from Aspergillus fumigatus (PC-7S-2 M), isolated from the Atlantic Forest of the Dog Head State Park (Paraná, Brazil) and later identified by morphological and molecular (ITS) methods. The mesophilic fungus was grown at 28 °C in liquid culture media containing Czapeck and 1% of different agroindustrial residues (w/v): passion fruit peel, Ponkan peel, barley brewing residue, soy flakes and ripe banana peel. Inoculants of 105 conidia ml-1 were incubated for 7 days, filtered and assayed for β-xylosidase intracellular activity obtaining a maximum value of 15 U ml-1 of the enzyme in the presence of barley brewing residue after 4 days of cultivation. Then, it was used a Central Composite Rotational Design (CCRD) to optimize the production of β-xylosidase, using barley brewing residue as carbon source at a significance level of p<0.10 which generated a predicted model of 245.04 U ml-1. Model validation provided an average optimized result equal to 229.06 U ml-1 for the enzyme. Thus, the production of β-xylosidase increased in 1,500% over the initially obtained for A. fumigatus in the presence of the barley brewing residue, therefore, achieving 93.47% of the predicted model. This finding emphasizes the availability of A. fumigatus β-xylosidase production with possible applications in several biotechnological process.
A biomassa lignocelulósica abundante nos resíduos agroindustriais, pode ser reutilizada como substrato barato para induzir a produção de enzimas, como β-Xilosidases. O objetivo deste trabalho foi analisar a produção de β-Xilosidase de Aspergillus fumigatus (PC-7S-2 M), isolado da Mata Atlântica do Parque Estadual Cabeça do Cachorro (Paraná, Brasil) e posteriormente identificado por métodos morfológicos e moleculares (ITS). O fungo mesofílico foi cultivado à temperatura de 28 °C em meios líquidos de cultura Czapeck, contendo 1% de diferentes resíduos agroindustriais (w/v): casca de maracujá, casca de pokan, bagaço de cevada, flocos de soja e casca de banana madura. Inóculos de 105 conídios mL-1 foram incubados durante 7 dias, filtrados e submetidos a dosagem de β-Xilosidase intracelular, obtendo-se um valor máximo de 15 U ml-1 para a enzima na presença de bagaço de cevada com 4 dias de cultivo. Assim, utilizou-se um delineamento composto central rotacional (DCCR) para otimizar a produção de -Xilosidase, usando o bagaço de cevada como fonte de carbono em um nível de significância p < 0,10, o qual gerou um modelo predito de 245,04 U ml-1. A validação do modelo forneceu um resultado otimizado médio igual a 229,06 U ml-1 para a enzima. Assim, a produção de β-Xilosidase aumentou em 1.500% em relação à obtida inicialmente para o fungo A. fumigatus na presença de bagaço de cevada como fonte de carbono (15 U ml-1), permitindo, deste modo, alcançar 93,47 % do modelo predito. Este achado ressalta a viabilidade de produção de β-Xilosidase de A. fumigatus com possíveis aplicações em vários processos biotecnológicos.

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49

Morley, Joseph Peter. "Studies of clinical and environmental isolates of Aspergillus fumigatus." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39567.

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Aspergillus fumigatus is a fungus of great environmental importance as well as being the most common filamentous fungal respiratory pathogen. Airborne A. fumigatus spores can reach potentially dangerous concentrations, particularly in the air around industrial composting sites. Drug resistant A. fumigatus infections are an increasingly common problem and the limited range of drugs available for the treatment of Aspergillus infections means that any resistance developing is a major cause for concern. Mycoviruses may offer an alternative approach to conventional treatment and exist in many fungal populations, including A. fumigatus, but there is little understanding of their importance or the influence they may have on their hosts. Different air samplers used in bioaerosol studies were evaluated. An enrichment protocol for the isolation of mycoviruses from environmental samples was assessed as well as further characterisation and genome sequencing of a mycovirus of the A. fumigatus type strain NCPF7367. For clinical and environmental A. fumigatus collections drug susceptibility was assessed using the EUCAST protocol, virulence compared using a Galleria model and the mating type of the fungi determined by PCR. Significant differences in sampler efficacy were observed. Putative mycoviruses were obtained from environmental samples and sequencing of the NCPF7367 virus genome suggests that this is a capsid-less virus. Increased azole resistance and virulence was found amongst compost-derived A. fumigatus relative to clinical isolates. This study highlights the importance of sampler selection in bioaerosol studies. A novel enrichment procedure for mycovirus isolation from environmental samples appears promising and the genome sequencing sheds new light on the lifecycle of an A. fumigatus mycovirus. The study also suggests that compost-derived A. fumigatus may be less susceptible to azole drugs and more virulent than clinical populations. Drug resistance may be more geographically variable than previously thought and intermediate-level resistance appears not to be mediated by cyp51-A mechanisms.

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Pihet, Marc. "Rôle de la mélanine dans la virulence d'Aspergillus fumigatus." Angers, 2013. http://www.theses.fr/2013ANGE0017.

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Dissertations / Theses on the topic 'Fumigants'

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