Dissertations / Theses on the topic 'Conidie'

Aspergillus niger is a black-spored filamentous fungus that forms asexual spores called conidospores (‘conidia’). Germination of conidia, leading to the formation of hyphae, is initiated by conidial swelling and mobilisation of endogenous carbon and energy stores, followed by polarisation and emergence of a hyphal germ tube. These morphological and biochemical changes which define the model of germination have been studied with the aim of understanding how conidia sense and utilise different soluble carbon sources for germination. Microscopy and flow cytometry were used to track the morphological changes and results showed that the germination of A. niger conidia was quicker and more homogenous in rich media than in minimal media. The germination of conidia was also shown to be quicker in the presence of D-glucose than D-xylose. In the absence of a carbohydrate, no visual indicators of germination were evident. Added to this, the metabolism of internal storage compounds was shown to only occur in the presence of a suitable carbon source. Specific environmental carbon sources may therefore serve as triggers of germination, i.e. to initiate the catabolism of stores such as D-trehalose and the swelling of conidia. Studies carried out using D-glucose analogues identified the structural features of sugars that trigger or support conidial germination. These studies showed that the arrangement of atoms on carbons 3 and 4, on the pyranose ring structure of D-glucose, are essential to serve as a trigger of germination. The trigger step preceeds, and is separate from, the energy generation step that supports the continued outgrowth. Transcriptomic studies found that the most significant changes were associated with the breaking of dormancy. The data also revealed that fermentative metabolism present at the early stages of spore germination is rapidly replaced by respiratory metabolism.

Scopo della tesi è presentare una piccola panoramica sulle coniche incentrata principalmente sui contenuti proposti nella scuola superiore: definizioni delle coniche come luoghi geometrici, alcune proprietà elementari, le loro equazioni canoniche, un esempio dei problemi proposti sui testi e applicazioni extra-geometriche. Successivamente sono presentate altre proprietà più specialistiche: similitudine ed eccentricità, classificazione affine e classificazione proiettiva delle coniche, per mostrare come questo argomento per essere affrontato in modo più vasto richieda nozioni che solitamente non fanno parte dei programmi della scuola superiore: similitudini, affinità, trasformazioni proiettive, matrici e loro rango, autovalori ed autovettori, forme quadratiche. Sono inoltre presentate alcune costruzioni realizzate con l’ausilio del software Geogebra, ormai diffuso in molte scuole, che riunisce in una sola pagina grafica sia il piano euclideo, tipico della "Geometria dinamica", sia il piano cartesiano su cui tracciare i grafici di funzioni, ed equazioni di coniche.

Les spores ou les conidies fongiques sont responsables de la dissémination des champignons filamenteux dans l'environnement (air, eau, sol,…). Ensuite les spores fongiques peuvent se déposer sur les équipements dans les ateliers de fabrication, sur les matières premières agricoles et sur les aliments. Au laboratoire, les spores sont obtenues en cultivant les champignons filamenteux en conditions optimales en termes de température, activité de l'eau, nutriments, de manière à obtenir le matériel biologique le plus rapidement possible. Or naturellement, lors de la sporulation, les champignons sont soumis à différents stress, notamment hydrique, ce qui entraîne des différences notables dans l'état physiologique de la spore. Ainsi notre objectif durant cette thèse est d’évaluer l’état physiologique des spores lorsqu’elles sont soumises à certaines conditions. Une première partie de la thèse vise à établir un nouveau modèle pour une meilleure détermination du temps de germination. L’étape suivante présente l’évaluation de l’influence du stress hydrique de la sporogénèse à la germination des spores. Les deux dernières parties présentent enfin l’évaluation des conditions de stockage sur la germination des spores. L’état physiologique est un facteur clé dans le processus de germination, il serait opportun de l’intégrer dans les modèles prédictifs de la germination
Fungal spores or conidia are responsible for filamentous fungi spread in environment (air, water, soil…). Then, they can be found on several environments including foods. In laboratory spores are obtained under favorable conditions. However, these conditions are not real, spores are subject to various stress including water stress after their formation. These conditions can make some interactions with their physiological state. Thus, our aim consists in evaluating spores physiological state after their exposition to various conditions of storage. First part of this thesis is about definition of a new model of germination for improving germination time determination. Next step concerns evaluation of water stress during spore’s germination process. The last two parts are finally dedicated to evaluation of storage condtions on spore’s germination time. Physiological state is a key factor in the germination process. It would be appropriate to include this factor in predictive models

Un problema in geometria è di tipo enumerativo se si cerca di calcolare il numero di certi oggetti geometrici, sotto certe condizioni che lo rendano finito. Tra questi, uno dei più noti, risale al 1848 ed è il problema di Jacob Steiner, professore di geometria all’Università di Berlino: “Date cinque coniche del piano proiettivo, quante sono le coniche tangenti a tutte cinque?”. Nel primo capitolo di questa tesi si richiamano le definizioni sulle coniche affini e proiettive mentre nel secondo si studia il problema di Steiner.

The hyphomycete Pseudozyma prolifica Bandoni was grown in batch and continuous liquid cultures to determine the influence of growth rate and nutrition on conidium development. In batch culture, a period of elongation and branch formation, followed by fragmentation, was typically observed. The stage of branch formation was almost completely eliminated when the amino acids phenylalanine, glutamic acid, or asparagine were substituted for nitrate. Substituting citric acid for glucose had a similar effect. Branch formation was enhanced in sucrose + nitrate medium. In batch cultures, branched growth occurred at the start of the exponential growth phase. In continuous culture, the extent of branching was dependent on the specific growth rate. Maximal branching was observed at growth rates near the maximum. Growth by elongation and "bud" formation was predominant at low growth rates, as at the end of the log phase in batch cultures. The conidia were also examined using fluorescence and electron microscopy. Staining with wheat germ agglutinin conjugated to Fluorescein Isothiocyanate indicated that some intercalary growth occurs.
Science, Faculty of
Botany, Department of
Graduate

Orientador : Claudio Luiz Messias
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Estudou-se a germinação e alguns aspectos da morfologia e fisiologia de Metarhizium anisopliae (METSCH.) SOROKIN, utilizando-se meios de cultura de diversas composições e também substâncias inibidoras de diversas naturezas. Observou-se a formação e o crescimento de tubos germinativos em conidios de linhagens selvagens, mutantes e diplóides. Verificou-se nos estudos iniciais que quando os conidios de M.anisopliae produzidos em meio mínimo, em culturas de superfície, eram expostos a ambiente ventilado, perdiam cerca de 50% de seu peso, pela evaporação da água em 6 horas. Verificou-se também que quando conídios produzidos de igual modo eram inoculados em meio completo líquido aumentavam seu volume em mais de 6 horas.Os estudos subsequentes mostraram que em 12 horas de incubação, mais de 85% de conídios germinaram nos vários meios testados, tanto sólidos como liquidas. Este tempo pode ser considerado como o tempo mínimo de germinação (TGm), para a variedade anisopliae. Os estudos também sugeriram que em meio liquido e à temperatura ambiente, uma concentração de 10_ conidios/ml, parece ser em algumas situações a mais indicada. Houve variabilidade quanto ao número de tubos germinativos em conídios de M.anisopliae num determinado tempo. A germinação e o crescimento de tubos germinativos podem ser representados por um modelo exponencial. Considerando também os vários meios de cultura testados, o meio mínimo + extrato de levedura se mostrou um meio basal para a germinação de conidios e crescimento de co1ônias. Foram ensaiadas várias substâncias inibidoras da germinação de conídios como, glicerol, polietilenoglicol, benzeno, clorofórmio, m-cresol, álcool éter + alquil-sulfato de sódio e cicloheximida, cujos efeitos permitiram em muitos casos um maior sincronismo na germinação. Algumas destas substancias além de osmoreguladoras, também produziram efeitos morfogênicos, aumentando o número de tubos germinativos dentro de um determinado tempo. Com m-cresol, o efeito morfogênico foi mais duradouro. Os mutantes da 1inhagem E9 não diferiram no modo de germinação quando comparados com a linhagem selvagem de origem, o mesmo não acontecendo com os mutantes de F84. A germinação de conídios dos diplóides, revelou cada um deles germinando de maneira diferente. O trabalho permitiu concluir que a germinação de conídios é um processo extremamente complexo, que segue um programa genético, o qual se expressa no tempo e no espaço e influenciado por diversos fatores ambientais
Abstract: Were studied on the germination of the Metarhizium anisopliae (METSCH) SOROKIN, and several aspects the morphology and physiology, utilizing culture media of various compositions and also inhibiting substances of various natures. The formation and growth of germinative tubes were observed in conidia of wild strains, mutant and diploid. The initial studies showed that when conidia the M.anisopliae produced in a minimum medium, in superficial cultures, were exposed to a ventilated environment they would loose 50% of their weight, by water evaporation in 6 hours. It was noticed also that when conidia produced in an equal manner were inoculated in a complete liquid medium they would increase their volume to more than 50% in 6 hours.The subsequent studies showed that in 12 hours of incubation more than 85% of the conidia germinated in the various tested media, such as for solids, as for liquids. This length can be considered as the minimum time for germination (TGm), for the anisopliae variety. The studies also suggested that in a liquid medium at the environmental temperature, a concentration of 10_ conidia/ml, it seems to be in some situations the most indicated. There was variability as to the number of germinative tubes in M.anisopliae conidia in a determined period of time. The germination and growth of germitiative tubes can be represented by an exponential model. Considering also the various tested culture media, the minimum + yeast extract demonstrated to be a basal medium for germination of conidia and growth of colonies. Various inhibiting substances of the conidia germination were tested, as glycerol, poliethileneglycol, benzene, chloroform, m-cresol, alcohol ether + alquil-sulphate of sodium and cicloheximide, being that the effects served in many cases to increase synchronism in germination. Some of these substances, besides being osmoregulators, also produced morphogenic effects, increasing the number of germinative tubes within a certain period of time. With m-cresol the morphogenic effect lasted longer.The mutants of strain E9 did not differ in the germination manner when compared to a wild origen, the same did not occur with the mutants F84. The germination of diploids conidia showed each of them germinating in a different manner. It was concluded by the study that the germination of the conidia is an extremely complex process, following a genetic program, which express in time and space and it is influenced by several environmental factors
Doutorado
Doutor em Ciências

Thesis (PhD(Agric))--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Postharvest decay of stone fruit in the Western Cape province of South Africa is caused primarily by Botrytis cinerea (grey mould) and Monilinia laxa (brown rot). Little is known about the relative importance and seasonal occurrence of the two pathogens in nectarine and plum orchards, the mode of penetration of fruits by M laxa, latency and subsequent disease expression by the latter pathogen. These aspects were investigated in this study. By sampling from the Unifruco Quality Evaluation Scheme and from 11 stone fruit orchards, observations were made over a 3-year period of the occurrence of grey mould and brown rot in the major stone fruit regions. Botrytis cinerea was found to be the most important pathogen causing blossom blight and postharvest decay on stone fruit. The pathogen was most prominent on early- and mid-season culti~ars. Brown rot was exclusively caused by M laxa and no evidence was found that M fructicoZa had been introduced into the region. Monilina laxa was most prominent on the later maturing cultivars. Botrytis cinerea blossom infection did not contribute directly to postharvest decay. Both surface inoculum and latent infection consistently occurred on fruit in each orchard, although at fluctuating levels. Disease expression on developing fruit was not governed by the amount of B. cinerea occurring on fruit surfaces, but by the ability of fruit to resist disease expression. The amount of B. cinerea on fruits was generally higher during spring than during summer. Monilinia laxa occurred sporadically on the blossoms of late-maturing cultivars. Immature fruit were generally pathogen-free and disease expression occurred on maturing fruit only. These findings suggest that conidia of M laxa are generally produced in orchards when fruits are approaching maturity and can penetrate and infect maturing fruit only. The behaviour of airborne M laxa conidia was subsequently studied on nectarine (cultivar Flamekist) and plum (cultivar Laetitia) fruit. For these studies, an inoculation method that simulates natural infection by airborne conidia was used. Fruit at pit hardening, 2 wk before harvest, harvest stage and after cold storage (nectarines 4 wk at -o.soC followed by 1 wk at 23°C at ±56% RH; plums 10 days at .....().5°C,18 days at 7.5°C followed by 1 wk at 23°C at ±56% RH) were dusted with dry conidia of M laxa in a settling tower. The fruits were incubated for periods ranging from 3 to 48 h at high relative humidity (2':93%, humid fruit) or covered with a film of water (wet fruit). Behaviour of the solitary conidia was examined with an epifluorescence microscope on skin segments stained in a differential stain containing fluorescein diacetate, aniline blue and blankophor. The ability of solitary conidia to colonise the fruit surface, penetrate fruit skins and to induce disease expression was determined by using a differential set of tests. For these tests, fruit were surface-sterilised (30 s in 70% ethanol) or left Unsterile. From each group, fruit were selected for isolation (skin segment test), immersed in a 3% paraquat solution (paraquat-treated fruit test) or left untreated (sound fruit test). 1be findings demonstrated that solitary conidia of M laxa behaved consistently on plum and nectarine fruit surfaces: appressorium formation and direct penetration was not observed on any of the fruit surfaces and germ tubes penetrated fruit predominantly through stomata, lenticels and microfissures in the fruit skin. The monitoring of airborne conidia revealed subtle effects of the fruits on the behaviour of solitary germlings, which could not be seen when using conidial suspensions. On both fruit types, no deleterious effect was seen on conidial and germling survival when fruit were kept humid at pit hardening, 2 wk before harvest and harvest. However, conidial and germling survival were drastically reduced by prolonged wet incubation of fruits. The findings on disease expression in the skin segment, paraquat-treated fruit and sound fruit tests clearly showed that the skin of both nectarine and plum fruits were not penetrated at the pit hardening stage, latent infections were not established and fruitsreacted resistant to disease expression. These facets on both fruit types were furthermore unaffected by wetness. The barrier capacity of the fruit skin of the two stone fruit types however differed drastically later in the season. On nectarine, fruit skins were more readily penetrated and disease expression became more pronounced when fruit approached maturity. Penetration and disease expression on ripening nectarine fruit were furthermore greatly influenced by wetness. Maturing plum fruit, on the other hand, did not display the drastic change in the barrier capacity of fruit skins as observed on nectarine. The influence of wetness on infection and disease expression was also less pronounced than on nectarine. In fact, plum fruit remained asymptomatic in the sound fruit test after inoculation and humid incubation at the 2 wk before harvest stage, harvest stage and after cold storage. Plum fruit at these stages only developed disease after a prolonged period (~12 h) of wet incubation. The paraquat fruit test revealed that these fruits became more susceptible to latent infection, but they were not as susceptible as nectarine. Collectively, these findings indicate that M. laxa fruit rot epidemics on plum and nectarine are driven by inoculum levels on fruit approaching maturity and by weather conditions prevailing during the preharvest and harvest period. However, the barrier capacity of plum skins is considerably more effective than that of nectarine fruit. Wounds would therefore play an important role in the epidemiology of M. laxa on plum fruit. Infection of fresh wounds by airborne M. laxa conidia, and by conidia and germlings that have established on fruits, was therefore investigated. Plum fruit (cultivar Laetitia) at pit hardening, 2 wk before harvest, harvest stage and after cold storage were dusted with dry conidia of M. laxa in a settling tower.- Infection of rionwounded fruit and of fresh wounds by \ the airborne conidia on dry, humid and wet plum fruit surfaces, and by conidia and germlings that have been established on fruits under the wetness regimes was then investigated. Nonwounded immature and mature fruit remained mostly asymptomatic, whereas nonwounded cold stored fruit decayed readily. Wounding drastically increased infection by airborne conidia. Immature fruits were less susceptible to wound infection by the airborne conidia than mature fruits. Conidia dispersed freshly were more successful in infecting fresh wounds than conidia that were deposited, or germlings that established, on fruit surfaces 4 days prior to wounding. This decrease in infectivity was especially pronounced on humid and even more on wet incubated fruit. This study clearly showed that in order to reduce. the incidence of brown rot, inoculum levels on fruit approaching maturity should be reduced by sanitation practices and fungicide applications. Furthermore, it is essential to protect fruits, especially. near-mature fruits, from being wounded.
AFRIKAANSE OPSOMMING: EPIDEMIOLOGIE VAN MONILINIA LAXA OP NEKTARIEN EN PRUIM: INFEKSIE VAN VRUGTE DEUR KONIDIA OPSOMMING Naoesverrotting van steenvrugte in die Wes-Kaap provinsie van Suid-Afrika word hoofsaaklik veroorsaak deur Botrytis cinerea (vaalvrot) en Monilinia laxa (bruinvrot). Min is bekend oor die relatiewe belang en seisoenale voorkoms van hierdie patogene in nektarienen pruimboorde, asook oor die infeksieweg, latensie en daaropvolgende siekte-uitdrukking van M laxa. Hierdie aspekte is in dié studie nagevors. \ \ Monsters IS oor 'n 3-jaar periode van die Unifruco Kwaliteitsevalueringskema, en ook van 11 steenvrugboorde verkry. Die voorkoms van vaalvrot en bruinvrot in die hoof steenvrugareas is so bepaal. Botrytis cinerea was die belangrikste patogeen wat betref bloeiselversenging en naoesverrotting. Verder was hierdie patogeen ook meer prominent op die vroeë- en middel-seisoen kultivars. Bruinvrot is uitsluitlik deur M Iaxa veroorsaak en geen aanduiding omtrent die moontlike voorkoms van M fructicola in Suid-Afrika is waargeneem nie. Monilinia laxa was meer prominent op die laat-seisoen kultivars. Botrytis cinerea bloeiselinfeksie het nie direk bygedra tot naoesverrotting nie. Beide oppervlakkige inokulum en latente infeksie het deurgaans, maar wel teen wisselende hoeveelhede, op vrugte in die onderskeie boorde voorgekom. Siekte-uitdrukking op ontwikkelende vrugte is egter nie beinvloed deur die hoeveelheid B. cinerea op die vrug nie, maar eerder deur die vermoë van die vrug om siekte-uitdrukking te onderdruk. Die hoeveelheid B. cinerea op vrugte was verder hoër gedurende lente as gedurende somer. Monilinia laxa het slegs sporadies op die bloeisels van laat-seisoen kultivars voorgekom. Groen vrugte was in die algemeen vry van die patogeen en siekte-uitdrukking het slegs op ryp vrugte plaasgevind. Hierdie bevindinge dui daarop dat M laxa in boorde hoofsaaklik op ryper vrugte geproduseer word. Hierdie swam infekteer ook net ryp vrugte. Die gedrag van luggedraagde M laxa conidia is bestudeer op nektarien- (kultivar Flamekist) en pruimvrugte (kultivar Laetitia). 'n Inokulasie-metode wat natuurlike infeksie deur luggedraagde konidia simuleer, is vir hierdie studies gebruik. Vrugte van die pitverharding-, twee weke voor oes-, oesstadium, asook koud-opgebergde vrugte (nektariene, 4 weke by -o.soe gevolg met 1 week by 23°C en ±56% RH; pruime, 10 dae by -O.5°e, 18 dae by 7.Soe gevolg deur 1 week by 23°C en ±56% RH), is met droë konidia in 'n inokulasietoring geïnokuleer. Die vrugte is vir periodes wat gewissel het van 3 tot 48 h geïnkubeer by hoë relatiewe humiditeit (~93% RH, vogtige vrugte), of dit is bedek met'n film water (nat vrugte). Die gedrag van die enkelspore (konidia) op die vrugoppervlak is met 'n epifluorisensiemikroskoop bestudeer. Skilsegmente is gekleur in 'n kleurstof, bevattende fluorisein diasetaat, analien-blou en blankofor. Die vermoë van die enkelspore om die vrugoppervlak te koloniseer, te penetreer en om siekte-uitdrukking te induseer, is met 'n differensiële stel toetse bepaal. Vir hierdie toetse is die vrugte oppervlakkig gesteriliseer (30 s in 70% etanol), of nie-steriel gelaat. In elke groep is vrugte geneem vir isolasie (skilsegment-to\~ts), of gedoop in "n 3% parakwat-oplossing (parakwat vrugtoets), of\, onbehandeld gelaat (onbehandelde vrugtoets ). Die. bevindinge het op die soortgelyke gedrag van M laxa enkelspore op die verskillende vrugsoorte gedui: appressoria en direkte penetrasie is nie waargeneem nie, en kiembuise het die vrugte hoofsaaklik deur huidmondjies, lentiselle en mikro-krakies .in die vrugskil gepenetreer. Deur luggedraagde spore te bestudeer, is sekere subtiele effekte van die vrug op die gedrag van enkelspore op die vrugoppervlak waargeneem. Op beide vrugtipes is geen nadelige effek op konidiurn- en kiembuisoorlewing opgemerk wanneer die vrugte onder hoë vogtoestande geïnkubeer is. Konidiurn- en kiembuisoorlewing is egter drasties verlaag hoe langer die vrugte onder nat toestande geïnkubeer is. Die bevindinge van die skilsegment-, parakwat en onbehandelde vrugtoetse het duidelik daarop gewys dat die vrugskil van nektarien en pruim nie gepenetreer is tydens die pitverhardingstadium nie, latente infeksies is nie gevorm nie, en die vrugte was bestand teen siekte-uitdrukking. Hierdie fasette op beide vrugtipes is ook nie beinvloed deur inkubasie-natheid nie. Die beskermingskapasiteit van die vrugskil van hierdie steenvrugtipes het egter drasties verskil later in die seisoen. Nektarien-vrugskille is meer geredelik gepenetreer en siekte-uitdrukking het toegeneem met rypwording. Penetrasie en siekteuitdrukking is verder in 'n groot mate deur inkubasie-natheid bevoordeel. Rypwordende pruime het egter nie so In drasties verandering in die beskermingskapasiteit van die vrugskil getoon nie. Die invloed van inkubasie-natheid op infeksie en siekte-uitdrukking was ook minder opsigtelik as op nektarien. Pruimvrugte van die twee weke voor oes-, oesstadium, en , koud-opgebergde pruime, wat onder hoë vog geïnkubeer is, het simptoomloos in die onbehandelde vrugtoets gebly. Vrugte van hierdie stadia het slegs simptome ontwikkel na periodes van langer as 12 h onder nat toestande. Die parakwat-behandelde vrugtoets het egter gewys dat die pruimvrugte meer vatbaar vir latente infeksies raak, maar steeds nie so vatbaar soos die nektarienvrugte nie. Gesamentlik dui hierdie bevindinge daarop <41tM laxa bruinvrot epidemies op pruim en nektarien afhanklik is van inokulumvlakke op rypwordende vrugte, asook die weerstoestande gedurende die vooroes- en oesstadia. Die beskermingskapasiteit van pruim vrugskille was egter aansienlik meer effektief as dié van nektarien vrugte. Wonde op vrugte sal dus 'n groter rol speel in die epidemiologic van M laxa op pruim. Infeksie van vars wonde deur luggedraagde M laxa konidia, en deur konidia en kiembuise wat reeds op die vrugoppervlak gevestig is, is gevolglik bestudeer. Pruimvrugte (kultivar Laetitia) van die pitverharding-, twee weke voor oes-, oesstadium, asook koud- \ \ opgebergde vrugte is in 'n inokulasie-toring geïnokuleer met droë M laxa konidia. .Infeksie , , van nie-gewonde vrugte en van vars wonde deur luggedraagde konidia op droë, vogtige en nat pruim vrugoppervlaktes, asook deur konidia en kiembuise wat reeds op die vrugoppervlak onder hierdie toestande gevestig is, is bepaal. Nie-gewonde groen tot ryp vrugte het meestal simptoomloos gebly, terwyl koud-opgebergde ryp vrugte wel verrot het. Wonde .het die hoeveelheid infeksie deur luggedraagde spore drasties vermeerder. Konidia wat geïnokuleer is op vrugte met vars wonde, was meer in staat om hierdie wonde te infekteer as konidia en kiembuise wat 4 dae voor wonding gevestig is. Hierdie afname in infektiwiteit was meer sigbaar op die vogtige, maar veral die nat vrugte. Hierdie studie het duidelik gewys dat inokulumvlakke op rypwordende vrugte verlaag moet word deur sanitasie-praktyke en fungisiedtoedienings. Dit is verder belangrik om vrugte, veral rypwordende vrugte, teen wonding te beskerm.

Cette these est consacree a l'etude experimentale et theorique d'une flamme quasi-conique de premelange air/ch#4 vibrant sous l'effet d'instabilites forcees de l'ecoulement amont. Ce dernier est soumis a une perturbation acoustique dont la frequence et l'amplitude sont imposees. La reponse de l'ecoulement a ete etudiee en presence et en absence de flamme. En reponse a la perturbation, la flamme prend differentes formes suivant le couplage frequence/amplitude ou encore nombre de strouhal/vitesse reduite acoustique. En fonction de ces parametres, nous avons etabli un diagramme regroupant les differentes configurations de flamme. Une etude geometrique et cinematique a ete appliquee a trois configurations de flamme selectionnees sur le diagramme: plissee, parametrique et chaotique. Les deux premieres subissent un plissement sous l'effet d'un ebranlement depuis la base du front jusqu'au sommet. La premiere est caracterise par l'apparition de cusps a forte amplitude et d'un phenomene de filtrage a forte frequence. La seconde se manifeste comme la reponse a une excitation parametrique decrite par l'equation de mathieu. Enfin la derniere presente un chaos uniquement spatial. L'etude geometrique a necessite la mise au point d'un nouveau systeme d'exploitation du traitement d'images. En confrontant les resultats cinematique et geometrique du jet force en presence et en absence de flamme, nous avons mis en evidence l'effet stabilisateur de la flamme sur le jet. Le modele theorique donnant l'equation d'evolution du front de flamme plissee, a ete resolu dans le cas de fortes perturbations en ecoulement compressible et incompressible. La compressibilite du champ de vitesse a introduit une variabilite de la vitesse normale de combustion. L'equation d'evolution du front presente un aspect non lineaire. Pour les fortes amplitudes, la solution correspondante est multivaleurs. Nous avons adapte la methode des caracteristiques pour resoudre cette equation en compressible et incompressible. Celle-ci etant ecrite sous forme conservative, la solution multivaleurs a ete corrigee, ce qui se traduit sur le front par des cusps representant bien le phenomene physique

La conidiation est un mécanisme de reproduction asexuée universel qui permet aux champignons filamenteux de se reproduire et de se propager dans l’environnement sous forme de conidies. Ce mécanisme est très utilisé pour produire des conidies pour fabriquer des produits fermentés comme les fromages, pour les biotechnologies avec la production d’enzymes et de composés d’intérêt, et pour la lutte biologique. Les conidies sont produites le plus souvent en culture de surface en milieu solide car la conidiation en culture liquide mmergée des champignons filamenteux n’est pas possible ou pas maîtrisée. C’est le cas de Penicillium camemberti, un des champignons les plus utilisés en agroalimentaire, mais très peu étudié au niveau physiologique et génétique, qui a servi de modèle pour cette thèse. L’objectif a été d’étudier le comportement de cette espèce en culture solide de surface et en culture liquide en faisant varier certains paramètres du milieu comme notamment la composition en azote et la température de croissance. Sur la base de mécanismes et données bio-informatiques de champignons modèles comme Aspergillus, des gènes clés impliqués dans la conidiation (brlA, wetA) et propriété de surface (rodA) ont été clonés et caractérisés pour la première fois chez P. Camemberti, et leur expression a été étudiée par RT-PCR quantitative dans différents types de cultures. L’absence de conidiation en culture liquide immergée est corrélée avec la très faible expression du gène rodA codant pour une hydrophobine, un type de protéines hydrophobes essentielles pour la biologie des champignons filamenteux. Des modifications de la composition azotée du milieu ont permis d’obtenir une conidiation en culture liquide immergée avec des modifications de propriétés de surface et un phénotype nouveau pour les conidies ainsi produites. Enfin, ce travail a révélé pour la première fois que certaines températures de croissance étaient capables, dans certaines conditions de composition azotée, d’induire une croissance de cette espèce en milieu liquide sous forme de microcycles de conidiation, avec une production massive de conidies (5. 108. Ml-1 de milieu)
Conidiation is an universal asexual reproduction mechanism enabling filamentous fungi to reproduce and propagate in the environment as conidies. This process is used to produce conidies that are employed in the manufacturing of fermented food, like cheese, in biotechnologies with the production of enzymes and compounds of interest and biological control. Conidies are generally produced in surface of solid-state culture because conidiation of submerged filamentous fungi in liquid medium is usually not possible or not controlled. This is particularly true for Penicillium camemberti, a very popular fungi in the food industry but that has not been much studied at the physiological or genetical levels. This microorganism was the subject of our study. The objective was to investigate its behaviour in solid- or liquid-state culture by modifying some medium parameters such as the nitrogen composition and the growth temperature. Based on mechanisms and bio-informatic data from model fungi such as Aspergillus, key genes involved in conidiation (brlA, wetA) and surface properties (rodA) were cloned and characterised for the first time in P. Camemberti, and their expression was studied by quantitative RT-PCR in different types of culture. The absence of conidiation in submerged liquid culture is correlated with the very weak expression of the rodA gene encoding a hydrophobin, a hydrophobic protein essential for the filamentous fungi biology. Modifications of the nitrogen composition of the medium resulted in conidiation in submerged liquid-state culture with a modification of the surface properties and a new phenotype for the conidies obtained in this way. Finally, this work showed for the first time that some growth temperatures, for specific nitrogen compositions, induced growth in liquid medium of conidiation microcycles with a massive production of conidies (5. 108. Ml-1 of medium)

La medecine nucleaire fournit, a partir de rayons emis par un radiotraceur injecte au patient, une information fonctionnelle sur l'organe etudie (cur, cerveau, thyroide, squelette. . . ) on considere aujourd'hui que les performances intrinseques du capteur d'anger - qui a subi de nombreuses ameliorations depuis sa creation en 1958 - liees a la surface sensible du detecteur, efficacite, resolution en energie, resolution spatiale et taux de comptage, ont atteint leurs limites. Deux axes de recherche se sont developpes afin d'ameliorer la qualite des images : les corrections des degradations d'origine physique et les nouvelles geometries d'acquisition. Trois problemes majeurs resident dans la reconstruction tridimensionnelle a partir de projections coniques. En premier lieu, une condition est imposee aux trajectoires d'acquisition pour assurer des mesures suffisamment exhaustives pour qu'une image tridimensionnelle puisse etre theoriquement reconstruite. Ensuite, il est necessaire de developper des algorithmes de reconstruction reellement tridimensionnels. En dernier lieu, des collimateurs coniques suffisamment precis doivent etre concus. Le but de cette these est de developper une methode algebrique de reconstruction tridimensionnelle a partir de donnees d'emission acquises avec un collimateur stenope. Meme si son champ d'application reste identique a celui des examens planaires realises en routine dans tous les services de medecine nucleaire, nous nous sommes fixes comme objectif l'etude de la glande thyroidienne.

Lo scopo principale di questa tesi è quello di fornire vari approcci didattici all'introduzione delle coniche, sia per scuole superiori che per l'università. Verranno studiate le coniche da un punto di vista storico e quindi come sezioni di un cono, analizzando e approfondendo proposizioni e definizioni tratte da Apollonio nel suo libro "Le Coniche" in cui compaiono le proprietà di tali curve, le quasi verranno successivamente studiate nel linguaggio della moderna geometria analitica. Dall'approccio storico si passa poi ad un approccio che usa la teoria generale delle curve algebriche piane (sia dal punto di vista affine che proiettivo), per poi andare a classificare le coniche sempre da un punto di vista affine, proiettivo ed euclideo. Si studieranno, infine le coniche inviluppo. Queste ultime verranno trattate sia geometricamente (attraverso il software di geometria dinamica: "GeoGebra") che analiticamente creando un collegamento tra la geometria e l'analisi in un modo nuovo e visuale.

Évaluer quantitativement les mouvements d'un patient lors d'un traitement par radiothérapie est un enjeu majeur. En effet, ces mouvements et ces déformations anatomiques induisent une incertitude balistique conduisant les thérapeutes à augmenter les marges de sécurité, ce qui peut empêcher de délivrer une dose suffisante à la région tumorale. Dans le cadre de cette thèse, nous nous sommes intéressés à l'estimation de ces mouvements dans les images obtenues juste avant le traitement par le scanner à faisceau conique. Pour cela, nous avons utilisé des algorithmes de recalage déformable. Dans un premier temps, nous avons cherché à améliorer la modélisation du mouvement respiratoire. Pour cela, nous nous sommes basés sur un modèle utilisant une segmentation de l'intérieur de la cage thoracique afin d'autoriser le glissement des organes internes contre cette dernière, tout en préservant un champ de déformation cohérent. La segmentation de l'intérieur de la cage thoracique est effectuée automatiquement par un algorithme qui prend en paramètres une segmentation des poumons et de la cage thoracique. Les algorithmes permettant de segmenter ces deux régions se sont avérés peu robustes, ce qui nous a poussé à les améliorer. Une fois ces structures bien segmentées, le modèle de transformation souffre d'un inconvénient majeur empêchant son utilisation dans un algorithme de recalage entre des projections 2D et une image 3D. En effet, il nécessite une segmentation 3D de l'intérieur de la cage thoracique dans les 2 images à recaler, ce qui est impossible à obtenir pour la série de projections 2D. Le modèle proposé dans cette thèse permet de contraindre les déformations à représenter des mouvements physiologiquement plausibles, tout en ne nécessitant qu'une seule segmentation de l'image 3D. Dans un deuxième temps, nous avons implémenté un algorithme de recalage 2D/3D utilisant le modèle de déformation proposé afin d'extraire le mouvement respiratoire des projections 2D de l'imageur à faisceau conique. Cet algorithme a été testé sur des images simulées dont les déformations étaient connues. Les résultats étant concluants, nous avons utilisé un algorithme de reconstruction compensée en mouvement dans le but de produire des images 3D sans flou respiratoire sur des données réelles. L'approche proposée permet d'obtenir une connaissance approfondie de l'anatomie du patient et de son mouvement respiratoire le jour du traitement, ce qui ouvre de nouvelles perspectives comme l'adaptation journalière du traitement, le calcul de dose prenant en compte le mouvement respiratoire et la re-planification de traitement. Cette approche de recalage entre une image 3D et des projections 2D est généralisable à d'autres mouvements et d'autres régions anatomiques
Motion estimation is a challenge in radiotherapy. It requires security margins to account for the incertitude on the tumor position. In this thesis, we address the problem of estimating the motion directly in the treatment room using the cone-beam projections. Firstly, we proposed a new breathing motion model that takes into account the sliding discontinuity between the rib-cage and the lungs. This method uses a segmentation of the inner part of the rib-cage which is obtained by an algorithm that requires the segmentation of the lungs and the rib-cage. The algorithms segmenting these parts were not robust enough and we proposed methods to improve their robustness. Compared to previous methods using this mask, our motion model is more robust to segmentation inconsistencies because it only requires a single mask instead of two consistent masks. Moreover, in case of 2D/3D registration, the computation of the second mask is usually not possible. The proposed model restricts the transformation to physically plausible motions and rely on a single segmentation. Secondly, we proposed a 2D/3D registration algorithm that uses our breathing model to extract motion from the cone-beam projections obtained just before the treatment. This algorithm was tested on simulated data. Then, we applied it to real data to reconstruct motion compensated images to remove motion blur from cone-beam CT. The proposed approach gives access to the patient motion just before the treatment, which can be used to daily adapt the treatment or to compute 4D dose maps. This approach can be used for other motions in other anatomic regions

Sorghum ergot, caused by Claviceps africana Frederickson, Mantle & de Milliano, is a disease that affects non-fertilized ovaries in sorghum male-sterile plants and infects hybrids if there is pollen sterility at flowering time. Sphacelia containing macroconidia could play a role in the survival of the pathogen. This study developed risk assessment models and evaluated environmental conditions affecting viability of macroconidia and transition from sphacelial to sclerotial tissues. Effect of weather on ergot severity was evaluated under natural conditions (in monthly planting dates) in nine sorghum genotypes at College Station, Weslaco, Rio Bravo, and Celaya. Panicles were inoculated daily beginning at flower initiation with a suspension of 1.6 x 106 C. africana conidia ml-1. Weather triad values were used to identify weather parameters correlated with the disease. Ergot severity was statistically greater in A-lines than hybrids because of the possible interference of pollen on some dates. Celaya had the greatest amount of ergot in hybrids. A-line ATx2752 had the lowest average ergot severity throughout years, locations and planting dates, as did the hybrid NC+8R18. Maximum and minimum temperature had a negative correlation with ergot at Rio Bravo, College Station and Weslaco, while at Celaya it was positive. The highest correlation was 7 to 9 days before initiation of flowering, suggesting that cooler temperatures during this period could cause male sterility. A-lines showed the same relationships between ergot and maximum and minimum temperatures after initiation of flowering. Minimum relative humidity had a positive correlation with ergot after initiation of flowering in both sorghum plant types. Sphacelia stored under cool temperatures (-3oC to 7oC) maintained conidial viability, and newly-formed sphacelia located on the sphacelia surface had the highest conidial viability. However, they show a greater viability reduction through time compared with conidia from older sphacelia, showing that conidial maturity can play a role in the survival of the conidia. Sphacelia on plants grown at 10oC, 20oC and 30oC with low relative humidity did not had any sclerotial development up to 4 weeks after formation of sphacelia. However, higher temperatures promoted an increase in the sphacelia dry weight during that time.

L'un des interets des antennes pastilles reside dans leur adaptabilite a etre integrees sur des surfaces courbes. Par contre dans la plage de frequences allant de 100 mhz a 1 ghz (bande u. H. F. Et v. H. F), leur principale limitation est due a leur taille. En effet, la longueur des antennes pastilles demi-onde est inversement proportionnelle a la frequence de travail. Pour diminuer d'une maniere importante la taille de ces antennes, il faut augmenter la permittivite effective ou la permeabilite effective des substrats. L'augmentation de la permittivite du substrat se faisant au detriment de la largeur de bande, nous examinons dans la premiere partie de ce travail l'interet des materiaux a forte permeabilite relativement a la bande passante. Pour analyser un reseau d'antennes pastilles gravees sur un substrat ferrimagnetique, nous utilisons une methode frequencielle qui permet de prendre en compte l'evolution de la permeabilite. L'approche dans le domaine spectral bidimensionnelle utilisee est bien adaptee, relativement simple a mettre en uvre, et efficace au niveau des temps de calcul. Cette methode predit la frequence de travail de l'antenne et permet d'acceder aux caracteristiques de rayonnement. Le logiciel developpe a ete valide, les nombreuses simulations effectuees n'ont pas permis de montrer l'interet des substrats magnetiques par rapport aux substrats dielectriques. Dans un second temps, nous avons modelise un reseau d'antennes pastilles conforme sur la surface exterieure d'un cone, recouvert ou non d'un radome de protection. Pour cela, nous avons adapte l'approche dans le domaine spectral au systeme de coordonnees cylindrique et spherique. Le logiciel developpe permet d'acceder a la frequence de resonance et aux caracteristiques de rayonnement des antennes

The cells of the airway epithelium play critical roles in host defense to inhaled irritants, and in asthma pathogenesis. These cells are constantly exposed to environmental factors, including the conidia of the ubiquitous mould Aspergillus fumigatus, which are small enough to reach the alveoli. A. fumigatus is associated with a spectrum of diseases ranging from asthma and allergic bronchopulmonary aspergillosis to aspergilloma and invasive aspergillosis. Airway epithelial cells have been shown to internalize A. fumigatus conidia in vitro, but the implications of this process for pathogenesis remain unclear. We have developed a cell culture model for this interaction using the human bronchial epithelium cell line 16HBE and a transgenic A. fumigatus strain expressing green fluorescent protein (GFP). Immunofluorescent staining and nystatin protection assays indicated that cells internalized upwards of 50% of bound conidia. Using fluorescence-activated cell sorting (FACS), cells directly interacting with conidia and cells not associated with any conidia were sorted into separate samples, with an overall accuracy of 75%. Genome-wide transcriptional profiling using microarrays revealed significant responses of 16HBE cells and conidia to each other. Significant changes in gene expression were identified between cells and conidia incubated alone versus together, as well as between GFP positive and negative sorted cells. The identification of biologically relevant responses in both species validates this methodology, and motivates further work to characterize the interactions between A. fumigatus conidia and primary airway epithelial cells obtained from normal and asthmatic patients.

Thesis (MScAgric)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The evaluation of fungicide efficacy in commercial vineyards can be influenced by the sporadic occurrence of Botrytis cinerea at various positions on vines, differences in bunch structure during bunch development and the phenomenon that symptom expression in shoots and bunches is governed by the resistance reaction of the various shoot and bunch parts. It has been postulated that, following air and water dispersal, infection by solitary conidia should playa prominent role in the epidemiology of B. cinerea on grapevine. The aim of this study was to determine (i) infection and (ii) fungicide efficacy at specific sites on shoots of vinelets and bunches (table grape cultivar Dauphine and the wine grape cultivar Merlot) inoculated with dry, airborne conidia of B. cinerea. Vinelets, prepared from cuttings, and bunches obtained from the vineyards at full bloom, pea size, bunch closure, véraison and harvest stages, were sprayed in a spray chamber at the recommended dosages with iprodione, pyrimethanil, cyprodinil/fludioxonil and fenhexamid or were left unsprayed. After 24 h the vinelets or bunches were dusted with dry conidia of Botrytis cinerea in a settling tower and incubated for 24 h at a high relative humidity (±93%). Following incubation, both the vinelets or bunches were divided into three groups. Vinelets and bunches of the one group were surface-sterilised, the others were left unsterile. Vinelets and bunches of one unsterile group were placed in dry chambers, kept for 14 days at 22°C with a 12 h photoperiod daily and monitored for symptom expression and the development of B. cinerea. Vinelets and bunches of the sterile group, and from one unsterile group were used for isolation. From each of these vinelets leaf blades, leaf petioles, shoots and inflorescences were removed. Sites used for isolation in bunch parts were rachises, laterals and pedicels, and sites on berries were the pedicel-end, cheek and style-end. The different parts and segments were placed in Petri dishes on Kerssies' B. cinerea selective medium, or on water agar medium supplemented with paraquat and incubated for 14 days at 22°C with a 12 h photoperiod daily. Infection and fungicide efficacy was determined by observing intact vinelets and bunches for symptom expression, and by estimating the amount of B. cinerea at the various sites on the vinelets and bunches with isolation studies. No symptoms of B. cinerea decay developed on sprayed and unsprayed vinelets that were kept in dry chambers during the 2 wk observation period. The isolation and incubation studies showed that the different fungicides were highly and nearly equally efficient in reducing superficial B. cinerea inoculum and latent infection. .In the case of leaf blades, which showed a high amount of B. cinerea on unsprayed vinelets under the two sterility regimes, decay was significantly reduced by each fungicide on both cultivars. This was not the case for the other parts, which yielded B. cinerea at low incidences under the two sterility regimes. The study with bunches showed that dry, airborne conidia, and the fungicide sprays, penetrated loose and tight clustered bunches from bloom to harvest and evenly landed on the various bunch parts. At full bloom, the amount of B. cinerea in unsprayed bunches was high on the laterals and pedicels, but low on the embryos. Unsprayed intact bunches at full bloom were highly susceptible to B. cinerea and developed symptoms of grey mould. The fungicides inhibited symptom expression at full bloom, but could not prevent infection. Unsprayed bunches inoculated at the other stages remained asymptomatic. The amount of B. cinerea was generally high in the rachises and laterals at pea size and bunch closure stages, and in the pedicel end of berries at harvest. Infection was constantly low in the berry cheek. The fungicides had a differential effect on infection at the various sites. In the case of rachises, the amount of B. cinerea was at each growth stage drastically reduced by each fungicide. In laterals, it was effectively reduced at pea size and bunch closure. However, at these two sites, significant differences were found between the fungicides in efficacy at stages when the amount of B. cinerea was high. This study showed that if these fungicides are applied properly to vine in commercial vineyards between budding and prebloom, during flowering, and at bunch closure, they should effectively prevent infection and symptom expression and thus the development of B. cinerea epiphytotics.
AFRIKAANSE OPSOMMING: INFEKSIE DEUR DROË, LUGGEDRAAGDE BOTRYTIS CINEREA KONIDIA EN DIE EFFEK VAN FUNGISlEDE OP VERSKILLENDE SETELS BINNE WINGERDTROSSE EN OP LOTE: Evaluering van fungisieddoeltreffendheid in kommersiële wingerde word beïnvloed deur die sporadiese voorkoms van Botrytis cinerea op verskeie posisies van wingerddele, verskille in trosstruktuur tydens trosontwikkeling, en die feit dat simptoomuitdrukking in lote en trosse deur die weerstandsaksie van die verskillende morfologiese dele van lote en trosse beheer word. In die natuur speel infeksie deur enkel konidia 'n prominente rol in die epidemiologie van B. cinerea van wingerd. Die doel van hierdie studie was om (i) infeksie en (ii) die effek van fungisiede op verskillende posisies op lote en trosse (tafeldruif kultivar Dauphine, wyndruif kultivar Merlot), wat met droë, luggedraagde konidia van B. cinerea geïnokuleer is, te bepaal. Lote, verkry vanaf steggies, en trosse versamel vanuit die wingerde tydens blom-, ertjiekorrel-, trostoemaak-, deurslaan- en oesstadium, is teen aanbevole dosisse met iprodione, pyrimethanil, cyprodinillfludioxonil of fenhexamid in 'n spuitkas bespuit, of is onbehandeld gelaat. Na 24 h is die lote en trosse met droë konidia van B. cinerea in 'n inokulasietoring geïnokuleer en daarna vir 24 h onder hoë humiditeit [±93% RH] geïnkubeer. Na inkubasie is die lote en trosse in drie groepe verdeel. Die een groep lote en trosse is oppervlakkig gesteriliseer om die patogeen op die oppervlakte te elimineer, en die ander twee groepe is onbehandeld gelaat. Die lote en trosse van een nie-steriele groep is vir 14 dae in droë voghokke by 22°C met 'n 12 uur daaglikse fotoperiode geplaas, en daagliks vir siekteuitdrukking en die ontwikkeling van B. cinerea gemonitor. Lote en trosse van die ander twee groepe is vir isolasiestudies gebruik. Vanaf elke loot is blaarskywe, blaarstele, internodes en ongeopende blomtrossies verwyder. Vanaftrosse is ragisse, laterale en korreisteie verwyder, en vanaf korrels is skilsegmente aangrensend aan die korrelsteel, die stempel-end, en die wang verwyder. Die dele en segmente is op B. cinerea selektiewe medium, en op paraquat medium in Petri bakkies geplaas en vir 14 dae by 22°C met 'n 12 uur daaglikse fotoperiode geïnkubeer. Infeksie en die fungisiedeffek is bepaal deur die intakte lote en trosse vir siekte- uitdrukking te monitor, en deur die hoeveelheid B. cinerea op verskeie posisies op lote en trosse te bepaal. Geen simptome het op enige posisie op bespuite en onbespuite lote, wat in droë hokke gehou is, ontwikkel nie. Die isolasie- en inkubasiestudies het getoon dat die verskillende fungisiede hoogs effektief op lote was, en inokulumvlakke van die patogeen doeltreffend verlaag het. In die geval van blaarskywe, wat hoë vlakke van B. cinerea op onbespuite steggies onder die twee steriliteitskondisies getoon het, is verrotting op beide kultivars betekenisvol deur die fungisiedes verlaag. Dit het egter nie vir die ander dele, waarop daar 'n lae voorkoms van B. cinerea onder die twee steriliteitskondisies was, gegeld me. Die studie met trosse het getoon dat droë, luggedraagde konidia en fungisiednewels beide oop en kompakte trosse vanaf blomstadium tot oes penetreer en eweredig op die verskillende dele land. Met blomstadium was die hoeveelheid B. cinerea in onbespuite trosse hoog op laterale en korrelstele, maar laag op die embrios. Onbespuite, intakte trosse was hoogs vatbaar vir B. cinerea by blomstadium en het simptome van vaalvrot ontwikkel. Die fungisiede het siekte-uitdrukking by blomstadium voorkom, maar kon nie infeksie voorkom me. Onbespuite trosse wat op ander stadia geïnokuleer is, het geen siekte-uitdrukking getoon me. Die hoeveelheid B. cinerea was hoër in die ragi, asook in laterale by ertjiekorrel- en trostoemaak stadium, en hoër in korreisteie by oesstadium. Infeksie was konstant laag in die korrelskil. Die fungisiede het 'n differensiële effek op infeksie by die verskillende posisies gehad. In die geval van ragi was die hoeveelheid B. cinerea drasties deur elke fungisied by alle groeistadia verlaag. In laterale was dit effektief by ertjiekorrel- en trostoemaakstadium verminder. By hierdie twee posisies waar die hoeveelheid B. cinerea hoog was, is daar egter betekenisvolle verskille in die doeltreffendheid van fungisiedes gevind. Hierdie studie toon dat as fungisiede behoorlik in kommersiële wingerde tussen botvorming en blomstadium, en tydens blom- en trostoemaakstadium toegedien word, infeksie en siekte-uitdrukking, en dus ook die epifitotiese ontwikkeling van B. cinerea, voorkom behoort te word.

Les espèces du complexe Scedosporium apiospermum sont des agents pathogènes émergents qui se situent au deuxième rang parmi les champignons filamenteux rencontrés au cours de la mucoviscidose. Ils sont omniprésents et particulièrement rencontrés dans les zones polluées. En dépit de leur importance clinique, nos connaissances sur leur biologie moléculaire et leur physiologie restent limitées. Chez les champignons, la paroi constitue un bouclier protecteur face à des conditions environnementales défavorables, et joue un rôle essentiel dans la pathogénicité. Ici, nous avons étudié les changements dynamiques de la paroi des conidies de S. boydii, l’une des deux espèces majeures de ce complexe avec S. apiospermum, avec pour objectif d'identifier des facteurs de virulence potentiels. En utilisant une large variété de techniques, allant de la microscopie électronique à balayage ou à transmission à l’analyse protéomique des protéines à ancre glycosylphosphatidylinositol (GPI) en passant par la microélectrophorèse et la partition de phase, la cytométrie en flux, la microscopie de force atomique, la résonance paramagnétique électronique, ou encore des techniques moléculaires, nous avons mis en évidence diverses modifications qui se produisent dans la paroi pendant la maturation et la germination des conidies de S. boydii et nous avons identifié la DHN-mélanine ainsi qu'un nombre important de protéines à ancre GPI. Enfin, nous avons fourni la première séquence complète du génome de S. apiospermum qui appuierait les différents domaines de la recherche sur ces champignons que ce soit pour l’étude des mécanismes pathogènes ou pour des applications biotechnologiques
Species of the Scedosporium apiospermum complex are emerging human pathogens which rank the second, after Aspergillus fumigatus, among the filamentous fungi colonizing the airways of patients with cystic fibrosis. These fungi are ubiquitous in nature and particularly encountered in polluted areas. Despite their clinical relevance, our knowledge about their molecular biology and physiology remains rather limited. In fungi, the cell wall forms a protective shield against adverse environmental conditions, and therefore plays a key role in pathogenesis, which makes it an interesting target for antifungal drug development. Here, in an attempt to identify potential virulence factors, we investigated the dynamic changes of the cell wall of conidia in S. boydii, one of the main pathogenic species within this species complex with Scedosporium apiospermum. Using various techniques, ranging from scanning and transmission electron microscopy to proteomic analysis of glycosylphosphatidylinositol (GPI)- anchored proteins, through two-phase partitioning and microelectrophoresis, atomic force microscopy and chemical force spectroscopy, flow 5 cytometry, electron paramagnetic resonance and molecular techniques, we highlighted various modifications occurring in the cell wall during maturation and germination of S. boydii and we identified DHN-melanin as well as a substantial number of GPI-anchored proteins in the cell wall. Finally, we provided the first publicly available genome sequence of S. apiospermum that would support various research fields on these fungi whether for understanding their pathogenic mechanisms or for various biotechnological applications

In questa tesi vengono studiate le sottovarietà di P^5 legate alla geometria delle coniche di P^2 e delle quadriche di P^3. L'insieme di tutte le coniche di P^2 costituisce uno spazio proiettivo di dimensione 5, le coniche degeneri costituiscono una ipersuperficie di grado 3 di P^5, mentre le coniche doppiamente degeneri costituiscono una superficie di grado 4, nota come superficie di Veronese. La grassmanniana delle rette di P^3 può essere vista come una ipersuperficie di grado 2 di P^5, detta quadrica di Klein, sulla quale le due famiglie di rette di una quadrica non singolare di P^3(C) corrispondono a due famiglie di coniche.

La tomographie à faisceau conique (CBCT) est devenue la modalité de référence pour les praticiens du domaine dentaire. Sa relative nouveauté et ses spécificités impliquent que le domaine du traitement de ces images est peu développé à l’heure actuelle. En partenariat industriel avec Carestream Dental, le premier volet de la thèse a conduit à développer une méthode de segmentation semi-automatique de chaque dent, reposant sur l’utilisation de contraintes de forme et d’intensité, et formulée comme un problème de minimisation d’énergie résolu par coupure de graphe. Les résultats montrent une bonne qualité de segmentation avec un coefficient de Dice moyen de 0, 958. Une application logicielle a été réalisée pour la mise en œuvre de la méthode de segmentation auprès des praticiens, en tenant compte des contraintes techniques et temporelles imposées par le contexte clinique, ainsi que du profil des utilisateurs. Un travail préliminaire d’extension de l’approche par coupure de graphe pour segmenter simultanément plusieurs dents à été réalisé, montrant la nécessité de rendre les contraintes de formes plus adaptées aux images et de modifier la méthode d’optimisation pour atteindre des temps de calcul compatibles avec la pratique clinique. Un second volet prospectif des travaux concerne la constitution d’un modèle structurel de la région maxillo-faciale pour formaliser les connaissances a priori sur les organes et leurs interactions. Ce modèle est un graphe conceptuel où sont représentés les concepts des structures et des relations. En particulier, les relations d’alignement et “le long de” ont été modélisées en 3D dans le cadre des ensembles flous
Cone-Beam computed tomography (CBCT) is the new standard imaging method for dental practitioners. The image processing field of CBCT data is still underdeveloped due to the novelty of the method and its specificities compared to traditional CT. With Carestream Dental as industrial partner, the first part of this work is a new semi-automatic segmentation protocol for teeth, based on shape and intensity constraints, through a graph-cut optimization of an energy formulation. Results show a good quality of segmentation with an average Dice coefficient of 0.958. A fully functional implementation of the algorithm has led to a software available for dentists, taking into account the clinical context leading to temporal and technical difficulties. A preliminary extension to multi-objects segmentation showed the necessity to get more stringent shape constraints as well as a better optimization algorithm to get acceptable computation times. The second part of this thesis, more prospective, is about the creation of a structural model of the maxillo-facial space, to formalize the a priori knowledge on organs and theirs spatial relations. This model is a conceptual graph where structures and relationships are seen as concepts. In particular, the spatial relations “Along” and “Aligned”, modeled in a fuzzy set framework, have been extended to 3D objects

La tomodensitométrie avec faisceau conique (CBCT) est actuellement utilisée en radiothérapie externe pour visualiser le patient dans la salle de traitement. Le mouvement respiratoire des patients y est encore difficilement pris en compte et des avancées sur le sujet pourraient améliorer la précision des traitements. En ce sens, l’obtention d’une séquence imageant les mouvements dans la région d’intérêt serait souhaitable. Ce mémoire présente le développement d’un algorithme de reconstruction 4D pour CBCT qui tente de répondre à certains besoins cliniques, soit l’obtention d’une qualité d’image suffisante, une facilité de mise en place clinique et une rapidité de calcul. L’algorithme 4D développé se base sur l’algorithme itératif convexe avec sous-ensembles ordonnés et régularisation de variation totale. Cette méthode a été choisie pour sa rapidité d’exécution, procurée par l’utilisation de sous-ensembles et la parallélisation des calculs sur carte graphique, et pour sa capacité à diminuer les artéfacts de rayons, communs en imagerie 4D, procurée par la régularisation de variation totale. La méthode développée pour obtenir une image 4D à partir d’acquisitions CBCT standards a fait appel à l’algorithme Amsterdam Shroud pour déduire le mouvement respiratoire de l’ensemble de projections CBCT. Elle a été validée sur un fantôme numérique et sur des acquisitions cliniques. Les résultats obtenus démontrent le potentiel de l’algorithme, puisqu’une image de résolution spatiale et temporelle satisfaisante a été reconstruite en moins de 5 minutes. Un tel temps de calcul se compare avantageusement à d’autres méthodes disponibles et ouvre la porte à une visualisation rapide du mouvement respiratoire en salle de traitement.
Cone beam computed tomography (CBCT) is currently used to visualize patients directly in the treatment room. However, the respiratory movement is still hardly taken into account and new developments could improve the precision of treatment. To this end, obtaining a film imaging movements in the region of interest would be beneficial. This master’s thesis presents the development of a reconstruction algorithm for 4D CBCT which seeks to respond to particular clinical needs, namely sufficient image quality, clinical implementation simplicity and high computational speed. The developed 4D algorithm is based on the ordered subsets convex iterative algorithm combined with the total variation minimization regularization technique. This method was chosen for its fast execution time, enabled by the use of subsets and the parallelization on GPU, and for its capability to reduce streaking artifacts, common on 4D imaging, enabled by the total variation regularization. The method developed to reconstruct a 4D image from standard CBCT scans employed the Amsterdam Shroud algorithm to deduce respiratory movement of a CBCT projections’ set. Its validation was performed on a numerical phantom and on clinical datasets. Results demonstrate the potential of the algorithm, since an image with sufficient spatial and temporal resolution was reconstructed in less than 5 minutes. Such computational times can be compared favorably with other available methods and could allow for online applications.

Septoria blight of celery (Apium graveolens var. dulce), induced by Septoria apiicola Speg., is a destructive disease that requires fungicide applications for its management. A reliable method of inoculum production was established. Best sporulation was obtained on celery agar (CA) at a predicted optimum temperature of 22.4$ sp circ$C. A moderate inoculum density within a range of 17-35 conidia/cm$ sp2$ of leaf surface provided non-coalescing lesions necessary for rapid enumeration. Initial blight incidence thresholds of about 0.6 and 0.5% to time the first fungicide application were established based on the proportion of maximum plant weight equivalent to the cost of one fungicide application calculated plant weight and petiole number per plant, respectively, in the summers of 1990 and 1991. The IBI levels of 0 and 2% to time the first fungicide application provided non-significant results in terms of the final amount of blight and yield. (Abstract shortened by UMI.)

Aspergillus ochraceus et Aspergillus carbonarius, contaminants fongique fréquents dans plusieurs produits agricoles, produisent de nombreux polycétones dont les mycotoxines. Durant ce travail, la diversité des gènes de polycétones synthases (PKSs), enzymes responsables de la biosynthèse des polycétones, présentes chez ces champignons a été étudiée en utilisant des couples d’amorces spécifiques et dégénérées. Au total, neuf PKSs différentes chez Aspergillus ochraceus NRRL 3174 et cinq PKSs différentes chez Aspergillus carbonarius 2Mu134 ont été identifiées. Elles sont distribuées dans les trois principaux groupes de PKS connus chez les champignons. Un des gènes identifiés chez Aspergillus ochraceus, AoKS1, est responsable de la biosynthèse de l’ochratoxine A. D’autre part, nous avons développé un système de détection et de quantification d’Aspergillus carbonarius par PCR en temps réel en ciblant un gène de polycétone synthase. Le système développé nous a ainsi permis aussi d’avoir une estimation rapide de la contamination en ochratoxine A dans le raisin à partir de la quantification d’ADN d’Aspergillus carbonarius. Enfin, une étude physiologique menée chez Aspergillus carbonarius pour connaître la répartition d’ochratoxine A dans les spores, le mycélium et le substrat a montré que la majorité de cette toxine se trouve accumulée au niveau des spores. Les résultats ont aussi montré que la toxine accumulée se rediffuse dans le milieu et arrive après 4 heures d’incubation à un niveau plus grand que celui de la valeur initiale. Ceci montre que les spores d’Aspergillus carbonarius peuvent participer à l’augmentation de l’ochratoxine A durant la macération dans les procèdes oenologiques. L’ensemble de ces travaux se situe dans le cadre de la gestion du problème des mycotoxines dans la chaîne alimentaire.

The fluffy gene of Neurospora crassa is required for asexual sporulation. It encodes an 88 kDa polypeptide containing a typical fungal Zn2Cys6 DNA binding motif. To identify the target genes on which FL may act, I sought to identify target sequences to which the FL protein binds. Several strategies were attempted to obtain purified FL protein. Purification was achieved by expressing the DNA binding domain of FL in Escherichia coli as a fusion with glutathione S-transferase followed by affinity purification using glutathione sepharose chromatography. DNA binding sites were selected by in vitro binding assays. Comparison of the sequences of selected clones suggested that FL binds to the motif 5??-CGG(N)9CCG-3??. A potential binding site was found in the promoter region of the eas (ccg-2) gene, which encodes a fungal hydrophobin. In vitro competitive binding assays revealed a preferred binding site for FL in the eas promoter, 5??-CGGAAGTTTCCTCCG-3??, which is located 1498 bp upstream of the eas translation initiation codon. In vivo experiments using a foreign DNA sequence tag confirmed that this sequence is a target site for FL regulation. Using Saccharomyces cerevisiae as an experimental system, I demonstrated that the C-terminal portion of FL functions in transcriptional activation. Microarray analysis was performed to study the role of fl in gene regulation on a large scale. mRNA levels in a fl mutant were compared to those in a strain overexpressing the fl gene. Experiments with cDNA microarray containing 13% of the total number of predicted N. crassa genes revealed 122 genes differentially expressed in response to overexpression of fl. Among these, eas displayed the greatest level of response. The cDNA microarray approach also revealed a number of genes that may be indirectly regulated by fl but may be involved in development. This information provides a foundation for further analysis of the role of fl in conidial development.

L'etude presentee dans ce document se place dans le cadre des antennes imprimees conformes et de leurs applications interferometriques. L'objectif de ce travail est d'evaluer l'efficacite d'une reception multicapteur pour effectuer des mesures goniometriques a bord d'un vehicule se deplacant a grande vitesse. Un reseau de quatre capteurs sur une surface de revolution conique a ete developpe. Ce reseau, couple a un systeme de mesures, permet de realiser la mesure coherente (amplitude et phase) des signaux recus sur chacune des voies. Afin de concevoir puis de caracteriser les antennes de reception, une methode analytique a ete developpee et implementee sur un systeme de calcul. Cette approche permet de connaitre les diagrammes de rayonnement des capteurs sur l'ensemble du secteur de mesures. Une methode numerique basee sur la resolution d'une equation integrale par la methode des moments (nec) permet egalement d'obtenir les caracteristiques de rayonnement des antennes. Des mesures ont ete realisees sur des antennes imprimees de revolution et sur des antennes patch imprimees sur une surface conique. Le test des methodes developpees a permis de valider les codes de calcul pour les differentes configurations envisagees. La determination de la direction d'incidence d'une source est proposee. Une etude theorique presente la modelisation d'un systeme de detection basee sur la connaissance des diagrammes de rayonnement des capteurs. Differents algorithmes de detection-estimation ont pu etre implementes et testes. Une comparaison des performances experimentales et theoriques des differents algorithmes est effectuee a partir d'un systeme permettant d'acquerir les donnees issues des voies des differents capteurs

Dans le contexte du traitement du cancer de la prostate, l’utilisation de la tomodensitométrie à faisceau conique (CBCT) pour la radiothérapie guidée par l’image, éventuellement adaptative, présente certaines difficultés en raison du faible contraste et du bruit important dans les images pelviennes. L’objectif principal de cette thèse est d’apporter des contributions méthodologiques pour le recalage automatique entre l’image scanner CT de référence et l’image CBCT acquise le jour du traitement. La première partie de nos contributions concerne le développement d’une stratégie de correction du positionnement du patient à l’aide du recalage rigide (RR) CT/CBCT. Nous avons comparé plusieurs algorithmes entre eux : (a) RR osseux, (b) RR osseux suivi d’un RR local dans une région qui correspond au clinical target volume (CTV) de la prostate dans l’image CT élargie d’une marge allant de 1 à 20 mm. Une analyse statistique complète des résultats quantitatifs et qualitatifs utilisant toute la base de données, composée de 115 images cone beam computed tomography (CBCT) et de 10 images computed tomography (CT) de 10 patients atteints du cancer de la prostate, a été réalisée. Nous avons également défini une nouvelle méthode pratique et automatique pour estimer la distension rectale produite dans le voisinage de la prostate entre l’image CT et l’image CBCT. A l’aide de notre mesure de distension rectale, nous avons évalué l’impact de la distension rectale sur la qualité du RR local et nous avons fourni un moyen de prédire les échecs de recalage. Sur cette base, nous avons élaboré des recommandations concernant l’utilisation du RR automatique pour la localisation de la prostate sur les images CBCT en pratique clinique. La seconde partie de la thèse concerne le développement méthodologique d’une nouvelle méthode combinant le recalage déformable et la segmentation. Pour contourner le problème du faible rapport qualité/bruit dans les images CBCT qui peut induire le processus de recalage en erreur, nous avons imaginé une nouvelle énergie composée de deux termes : un terme de similarité globale (la corrélation croisée normalisée (NCC) a été utilisée, mais tout autre mesure de similarité pourrait être utilisée à la place) et un terme de segmentation qui repose sur une adaptation locale du modèle de l’image homogène par morceaux de Chan-Vese utilisant un contour actif dans l’image CBCT. Notre but principal était d’améliorer la précision du recalage comparé à une énergie constituée de la NCC seule. Notre algorithme de recalage est complètement automatique et accepte comme entrées (1) l’image CT de planification, (2) l’image CBCT du jour et (3) l’image binaire associée à l’image CT et correspondant à l’organe d’intérêt que l’on cherche à segmenter dans l’image CBCT au cours du recalage
The use of CBCT imaging for image-guided radiation therapy (IGRT), and beyond that, image-guided adaptive radiation therapy (IGART), in the context of prostate cancer is challenging due to the poor contrast and high noise in pelvic CBCT images. The principal aim of the thesis is to provide methodological contributions for automatic intra-patient image registration between the planning CT scan and the treatment CBCT scan. The first part of our contributions concerns the development of a CBCT-based prostate setup correction strategy using CT-to-CBCT rigid registration (RR). We established a comparison between different RR algorithms: (a) global RR, (b) bony RR, and (c) bony RR refined by a local RR using the prostate CTV in the CT scan expanded with 1- to-20-mm varying margins. A comprehensive statistical analysis of the quantitative and qualitative results was carried out using the whole dataset composed of 115 daily CBCT scans and 10 planning CT scans from 10 prostate cancer patients. We also defined a novel practical method to automatically estimate rectal distension occurred in the vicinity of the prostate between the CT and the CBCT scans. Using our measure of rectal distension, we evaluated the impact of rectal distension on the quality of local RR and we provided a way to predict registration failure. On this basis, we derived recommendations for clinical practice for the use of automatic RR for prostate localization on CBCT scans. The second part of the thesis provides a methodological development of a new joint segmentation and deformable registration framework. To deal with the poor contrast-to-noise ratio in CBCT images likely to misguide registration, we conceived a new metric (or enery) which included two terms: a global similarity term (the normalized cross correlation (NCC) was used, but any other one could be used instead) and a segmentation term based on a localized adaptation of the piecewise-constant region-based model of Chan-Vese using an evolving contour in the CBCT image. Our principal aim was to improve the accuracy of the registration compared with an ordinary NCC metric. Our registration algorithm is fully automatic and takes as inputs (1) the planning CT image, (2) the daily CBCT image and (3) the binary image associated with the CT image and corresponding to the organ of interest we want to segment in the CBCT image in the course of the registration process

Le séchage est une opération unitaire pratiquée depuis des millénaires pour laquelle les connaissances scientifiques sont encore très incomplètes. Il est cependant de plus en plus nécessaire de « bien » sécher afin d’atteindre une combinaison optimale du temps de séchage, de l’énergie consommée et surtout de la qualité du produit final. Ceci est d’autant plus vrai dans le cadre du séchage alimentaire où de nombreux produits sont très sensibles à la température et à la déshydratation. C’est le cas de la levure de boulanger dont la capacité à dégager du CO2, pour faire gonfler la pâte à pain par exemple, diminue très souvent lorsque le séchage est réalisé dans des mauvaises conditions opératoires. L’utilisation de séchoirs particuliers tels que les lits à jet coniques devrait permettre d’améliorer le séchage en terme d’efficacité et de qualité finale. L’objectif principal de cette thèse est de contribuer à mieux comprendre et modéliser le séchage de levures en lit à jet conique en utilisant une approche multi-échelles.

Le séchage d’un grain de levure isolé est caractérisé à l’aide d’un nouveau dispositif thermogravimétrique dans lequel il est possible de mesurer l’évolution des dimensions du grain ainsi que sa température de surface. Les résultats obtenus sont alors utilisé pour construire et valider un nouveau modèle du séchage d’un grain de levure basé sur l’existence de trois types d’eau et permettant de prédire l’évolution du contenu en eau et de la température du grain. L’analyse combinée du modèle et des résultats expérimentaux permet de mettre en avant que le rétrécissement des grains de levures au cours du séchage n’a pas d’impact significatif sur la vitesse de séchage et qu’il est essentiel de modéliser correctement la température du grain.

L’écoulement de solides dans le lit à jet conique est caractérisé expérimentalement au moyen de la technique de poursuite de particule radioactive (RPT). Un post-traitement des données brutes (évolution temporelle de la position du traceur) est développé pour déduire un certain nombre de paramètres liés à l’écoulement du solide :forme des régions du lit à jet (jet, anneau et fontaine), distributions de l’écoulement des solides entre les régions, distribution de temps de séjour des solides dans le lit, vitesses et débits moyens des solides, et taux de gaz dans le jet et l’anneau. Les résultats expérimentaux ont notamment permis de montrer que la forme du jet ne dépend quasiment pas de la vitesse d’injection de l’air; de même, le rapport du débit volumique de solides d’une région du lit à l’autre avec la vitesse moyenne du solide dans l’anneau donne une valeur constante pour une hauteur de lit stagnant donnée. Des corrélations empiriques sont également développées pour prédire les vitesses et débits moyens de solides ainsi que les temps de séjour moyens des solides dans les différentes régions du lit.

L’écoulement du gaz dans le lit à jet conique est caractérisé expérimentalement par la mesure des distributions de temps de séjour (RTD) du gaz dans le lit par l’injection et la détection d’un gaz radioactif dans le lit à jet en opération. L’existence d’un écoulement non négligeable du gaz dans l’anneau du lit est mise en évidence. Les vitesses moyennes du gaz dans le jet et l’anneau ainsi que la portion du débit total qui passe dans le jet sont déduites des courbes de RTD. Il est identifié que le gaz circule au moins deux fois plus vite dans le jet que dans l’anneau, ce qui mène à des échanges de matières entre un solide et le gaz plus intenses dans le jet que dans l’anneau.

Des expériences de séchage de levure sont réalisées dans un lit à jet conique afin de caractériser l’effet des conditions opératoires sur le séchage. Un nouveau modèle multi-échelles décrivant le séchage de levure en lit à jet est présenté; celui-ci est basé sur les résultats des caractérisations expérimentales et des modélisations du séchage d’un grain de levure isolé et de l’écoulement solide-gaz dans le lit à jet conique. Le modèle phénoménologique ne possède qu’un seul paramètre et permet de très bien reproduire les résultats des expériences de séchage de levure en lit à jet conique. Il tient notamment compte du fait que dans un lit à jet, la saturation de l’air en vapeur d’eau au passage du lit peut être un phénomène limitant pour la vitesse de séchage, surtout en début de séchage.

La caractérisation de l’évolution au cours du séchage de la capacité de la levure à dégager du CO2 dans une pâte à pain a également été réalisée pour un grain de levure isolé et pour le séchage en lit à jet conique. Des conclusions similaires sont présentées dans les deux cas. En effet, la dégradation de la levure est liée à l’enlèvement de l’eau intracellulaire (type D, fin du séchage en-dessous de contenu en eau d’environ 0,5 (d.b.)) et c’est avant tout la vitesse avec laquelle cette eau est enlevée qui contrôle la qualité finale du produit. L’enlèvement de l’eau intercellulaire (type E, début du séchage) n’a pas d’influence significative sur la dégradation de la levure. Dans tous les cas, la dégradation est amplifiée lorsque la température du solide dépasse 40°C.

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Drying is a unit operation that is practiced since thousands of years and which for scientific knowledge is still very incomplete. However it is more and more necessary to dry « well » in order to reach an optimal combination between drying duration, consumed energy and also final product quality. This is even truer in the case of food drying involving a lot of products that are very sensitive to temperature and dehydration. Baker’s yeast often encounters a drastic decrease of its gassing power, which makes for instance inflate bread dough, when drying is operated in wrong conditions. Using special driers such as conical spouted beds should allow improving drying in terms of efficiency and final quality. The main objective of this thesis is to contribute to better understand and model Baker’s yeast drying in a conical spouted bed by using a multiscale approach.

Drying of a single Baker’s yeast pellet is characterised by using a new thermogravimetric set up where the evolution of the pellet dimensions and surface temperature can be measured during drying. The obtained results are then used to develop and validate a new model of the drying of a Baker’s yeast pellet. The model is based on the existence of three types of water in yeast and it allows predicting the evolution of the pellet’s moisture content and temperature during drying. The combined analysis of the model and the experimental results permits to put forward that pellet’s shrinkage during drying have no significant influence on the drying rate and that it is really essential to correctly model the pellet’s temperature.

Solid flow in the conical spouted bed is experimentally characterised by using a radioactive particle tracking technique (RPT). A post-treatment of rough data (time-evolution of the tracer position) is developed in order to predict a series of parameters linked to the solid flow: shape of the bed regions (spout, annulus and fountain), distributions of solid flow in the bed regions, residence time distribution of the solids in the bed, mean solids velocities and flowrates, and voidage in the spout and annulus. Experimental results allowed to show that the shape of the spout is nearly not influenced by inlet air velocity; also, the ratio of volumetric solid flowrate between the different regions of the bed and of the mean solids velocity in the annulus has a constant value for a given static bed height. Empirical correlations are also developed in order to predict the mean solids’ velocities and flowrates, and the mean residence time of the solids in each region of the bed.

Gas flow in the conical spouted bed is experimentally characterised by measuring gas residence time distributions (RTD) in the bed through the injection and detection of a radioactive gas tracer into the operated spouted bed. The existence of non-negligible gas flow in the annulus of the bed is highlighted. Mean gas velocities in the spout and annulus, and the part of the total gas flow going to the spout are deducted from the RTD curves. It is identified that gas moves at least twice faster in the spout than in the annulus, which leads to mass exchanges between solid and gas that are more intense in the spout than in the annulus.

Baker’s yeast drying experiments are done in a conical spouted bed in order to characterise the effects of operating conditions on drying. A new multiscale model, describing Baker’s yeast drying in conical spouted bed, is presented; it is based on experimental results and on the models of a single pellet drying and of gas-solid flows in the conical spouted bed. This phenomenological model has only one unknown parameter and permits reproducing the experimental results of Baker’s yeast drying in conical spouted bed. It takes into account the fact that, in a spouted bed, vapour saturation of the air during its residence time in the bed can be a limiting phenomena for the drying rate, especially in the beginning of the drying.

The characterisation of the evolution of the Baker’s yeast gassing power in a bread dough during the drying has also been done in the case of a single pellet drying and in the case of spouted bed drying. Similar conclusions are presented for both cases. Indeed, yeast degradation is linked to intracellular water removal (type D, end of the drying below a moisture content of around 0,5 (d.b.)) and it is mostly the rate of this water removal that controls the final quality of the product. Intercellular water removal (type E, beginning of the drying) has no significant influence on yeast degradation. In all the cases, degradation is amplified when solid temperature is higher than 40°C.

Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Alternaria solani, cause of early blight, threatens potato yields. Fungicide resistance has made control of early blight difficult and there are concerns that in-season fungicide use results in resistance to boscalid, fluopyram, and chlorothalonil. Concern of high levels of resistance to boscalid a group 7 fungicide may confer cross-resistance to fungicides of the same group such as fluopyram. From 2014 to 2015, A. solani isolates were collected from field plots treated with boscalid, fluopyram, and chlorothalonil to test resistance levels. Isolates were determined resistant if EC50 values were higher than 5 µg ml-1. Boscalid and chlorothalonil mean EC50 values decreased two fold from 2014 to 2015, while fluopyram values increased two fold. A negative correlation between fluopyram and boscalid indicate no cross-resistance. Higher resistance levels to fluopyram (17.1 µg ml-1) were observed in the treatment C-14 where only fluopyram was applied in 2014. Treatments D-14 and D-15, only treated with chlorothalonil, had the highest mean EC50 values to chlorothalonil (2.3 and 1.1 µg ml-1, respectively). Field trials show fluopyram+chlorothalonil had lowest disease severity of 6.6 to 6.8%. Leaf residues of boscalid fluopyram, and chlorothalonil measured an average of 10.2, 4.9, and 55.0 ppm on leaves throughout the canopy. After 14 days average residues diminished to 0.74, 0.39, and 16.9 ppm for boscalid, fluopyram and chlorothalonil, respectively. Boscalid is not effective for early blight control because of high resistance; fluopyram resistance is increasing as treatments of fluopyram are applied; and chlorothalonil does not seem to be affected by continued fungicide application.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The paracoccidioidomycosis (PCM) is a systemic disease caused by the thermo dimorphic fungus Paracoccidioides spp.. The route of infection of the PCM occurs by the inhalation of conidia or mycelia fragments. Until now, no proteomic studies were performed with conidia of Paracoccidioides sp. In this sense, characterize the proteome of the conidia, may contribute to the detailed knowledge of the proteins expressed during the propagation phase and their potential roles in virulence and pathogenicity, providing possible targets for antifungal strategies. For the conidia production, the mycelia of isolate Pb01 (ATCC MYA-826) were cultured in potato agar medium during 90 days at 18 ºC. After production, the conidias were collected and purified. The proteins were extracted and subjected to tryptic digestion with subsequent identification by NanoUPLC-MSE. We identified a total of 242 proteins of conidia of Paracoccidioides. The in silico analysis were used to characterize the proteins present in Paracoccidioides conidia. Proteins as GAPDH, enolase, triosephosphate isomerase, and some glycoproteins like ECM33 and β-1,3-glucanosyltransferase gel2 were identified during analysis. Some of these have been described as adhesins in Paracoccidioides and in other pathogenic fungi. Were also identified proteins related to signal transduction pathways, such as: Ras GTPase, RhoA GTPase and calmodulin, described in other fungi involved in morphologic changes. Proteins related to evasion, defense and virulence of the fungus, such as HSP90, catalase, mitochondrial peroxiredoxin Prx1, have been described with functions related to temperature shifts or oxidative stress provided by the host environment, were also identified. These results highlight that Paracoccidioides conidia contain proteins that can contribute to its maintenance in the environment and have molecules related to important processes necessary for the initial steps of infection in the host.
A paracoccidioidomicose (PCM) é uma micose sistêmica causada pelo fungo termodimórfico Paracoccidioides spp.. A principal rota de infecção da PCM ocorre por inalação de conídios ou fragmentos de micélio. Até o momento, estudos proteômicos não foram realizados com conídios de Paracoccidoides sp. Neste sentido, caracterizar o proteoma do conídio poderá contribuir para o conhecimento detalhado das proteínas expressas durante a fase de propagação e seus potenciais papéis na virulência e patogenicidade, fornecendo prováveis alvos para estratégias antifúngicas. Para a produção de conídios, o micélio do isolado Pb01 (ATCC MYA-826) foi cultivado em meio ágar batata durante 90 dias a 18 ºC. Após a produção, os conídios foram coletados e purificados. As proteínas foram extraídas e submetidas a digestão tríptica com subsequente identificação por NanoUPLC-MSE. Foram identificados um total de 242 proteínas de conídios de Paracoccidioides. As análises in silico foram utilizadas para caracterizar as proteínas presentes em conídios de Paracoccidioides. Proteínas como a GAPDH, enolase, triosefosfato isomerase e algumas glicoproteínas como ECM33 e β-1,3-glicanosiltransferase Gel2 foram identificadas durante as análises. Algumas destas já foram descritas como adesinas em Paracoccidioides e em outros fungos patogênicos. Também foram identificadas proteínas relacionadas as vias de transdução de sinais, tais como: Ras GTPase, RhoA GTPase e calmodulina, descritas em outros fungos envolvidas em alterações morfológicas. Proteínas relacionadas à evasão, defesa e virulência do fungo, tais como HSP90, catalase B, peroxiredoxina mitocondrial Prx1, foram descritos com funções relacionadas a mudanças de temperatura ou estresse oxidativo proporcionado pelo ambiente hospedeiro, também foram identificados. Esses resultados demonstram que o conídio de Paracoccidioides contem proteínas que podem contribuir para sua manutenção no meio ambiente e possuem moléculas relacionadas a processos importantes necessários para os passos iniciais da infecção no hospedeiro.

La conidiation de Penicillium camemberti, un ferment d'affinage, a été étudiée en culture de surface, d'un point de vue physiologique et moléculaire. Le développement d'une technique d'inoculation par trempage de filtre a permis de travailler sur un matériel biologique homogène et de réaliser des transferts de mycélium d'un milieu à un autre. Dans ces conditions de culture, il a été démontré que le nitrate de potassium stimule la conidiation, alors que le sulfate d'ammonium l'inhibe. Le temps nécessaire à l'acquisition de la compétence a été évalué à 51 heures. Différents facteurs nutritionnels ont ensuite été testés pour déterminer leur influence, soit positive, soit négative, sur la conidiation de Penicillium camemberti. L'étude de l'effet du calcium et du rapport carbone sur azote (C/N) a alors été approfondie. D'une point de vue moléculaire, nous avons identifiés les gènes brlA et wetA, potentiellement impliqués dans le contrôle de la conidiation de Penicillium camemberti. L'analyse de l'expression du gène brlA a mis en évidence une corrélation entre le niveau d'expression de ce gène et le taux de conidiation. La qualité des conidies a été étudiée en fonction des conditions de culture, notamment liquide et solide. Le dosage du contenu des conidies en polyols et tréhalose ainsi qu'une analyse ultrastructurale nous a permis d'interpréter les différences de résistance à la lyophilisation et de capacité de couverture d'un milieu fromage
The conidiation of Penicillium camemberti, a ripening fungus, was examined on solid media from a physiological and molecular point of view. The development of a technique of inoculation by soaking filters made possible to work on a homogeneous biological material and to transfer easily mycelium from a medium to an another. Under these conditions of culture, it was shown that potassium nitrate stimulates the conidiation, whereas ammonium sulfate inhibits it. The time necessary to acquire the competence was evaluated at 51 hours. Various nutritional factors were then tested to determine their influence, either positive, or negative, on the conidiation of Penicillium camemberti. The effect of calcium and the carbon to nitrogen ratio (C/N was then thoroughly studied. From a molecular point of view, we identified the brlA and wetA genes, potentially implied in the control of the conidiation of Penicillium camemberti. The analysis of the expression of the brlA gene highlighted a correlation between the level of expression of this gene and the rate of conidiation. The quality of the conidies was studied according to the conditions of culture, in particular liquid and solid. The determination of the polyols and trehalose contents of the conidies as well as an ultrastructural analysis enabled us to interpret differences into resistance to freeze-drying and capacity of covering a cheese medium

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Os fungos são reconhecidamente cosmopolitas e desenvolvem diversas funções ecológicas no ecossistema, entre elas a decomposição da matéria orgânica. Eles reciclam a serapilheira presente no solo, contribuindo para mineralização de nutrientes. Nos ambientes aquáticos, esse papel saprofítico, contribui para aumentar a palatabilidade do material vegetal utilizado por organismos de outros níveis tróficos. Diversos representantes do reino Fungi estão presentes nos ambientes aquáticos e, dentre esses, os fungos conidiais. No bioma da Mata Atlântica os estudos sobre fungos no ambiente aquático ainda são escassos. Assim, o presente trabalho teve como objetivo realizar um estudo taxonômico e filogenético das espécies de fungos conidiais associadas a substratos vegetais em decomposição submersos em corpos d’água de três fragmentos florestais localizados na Serra do Brigadeiro, Minas Gerais. As amostras coletadas foram levadas ao Laboratório de Micologia e Etiologia de Doenças Fúngicas de Plantas da Universidade Federal de Viçosa onde foram feitos os isolamentos e identificação dos fungos associados. O gênero Cladosporium foi o grupo de fungos mais abundante. Por meio da morfologia das estruturas vegetativas e reprodutivas desse fungo, do crescimento das culturas in vitro e de análises filogenéticas, concluiu-se que todos os isolados pertencem ao complexo Cladosporium cladosporioides, sendo dois deles relatados pela primeira vez no Brasil e uma espécie nova a ser proposta. Este estudo contribui para ampliar o conhecimento da diversidade de fungos conidiais em ambientes aquáticos na Mata Atlântica Brasileira e ressalta a importância de se explorar novos habitats em pesquisas micológicas.
Fungi are recognized as cosmopolitan and carry out various ecological functions in the ecosystem, including the decomposition of organic matter. They recycle the litter present in the soil, contributing to mineralization of nutrients. In aquatic environments, this saprophytic role contributes to increase the palatability of plant material used by organisms of other trophic levels. Several representatives of the Fungi kingdom are present in the aquatic environments and, among these, the conidial fungi. In the Atlantic Forest biome, studies on fungi in the aquatic environment are still scarce. The aim of this work was to carry out a taxonomic and phylogenetic study of the conidial fungi species associated with decomposed plant substrates submerged in water bodies of three forest fragments located in the Serra do Brigadeiro, Minas Gerais. The collected samples were taken to the Laboratório de Micologia e Etiologia de Doenças Fúngicas de Plantas of Universidade Federal de Viçosa, where the isolations and identification of associated fungi were made. The genus Cladosporium was the most abundant fungal group. By means of the morphology of vegetative and reproductive structures of this fungus, the growth of in vitro cultures and phylogenetic analyzes, it was concluded that all the isolates belong to the Cladosporium cladosporioides complex, two species reported for the first time in Brazil and a new species be proposed. This study contributes to increasing the knowledge of the diversity of conidial fungi in aquatic environments in the Brazilian Atlantic Forest and emphasizes the importance of exploring new habitats in mycological researches.

Le principe de la tomographie d'emission mono-photonique est d'administrer au patient un radioelement qui va se fixer dans l'organe a etudier. A partir d'un ensemble de mesures du rayonnement emis acquises autour du patient, un algorithme de reconstruction calcule la distribution de l'activite d'emission, fournissant une information fonctionnelle de l'organe. Les mesures sont perturbees par differents phenomenes, en particulier par l'attenuation a travers les tissus traverses qui constitue un obstacle majeur pour assurer une bonne quantification de l'activite emise. Ce travail a pour but de batir une methode de reconstruction corrigeant l'attenuation. On suppose que la distribution d'attenuation de l'objet a ete obtenue par reconstruction a partir de mesures de transmission. La methode de reconstruction proposee est une methode algebrique ou les mesures sont reliees a l'image recherchee par une equation matricielle qu'il s'agit de resoudre. Nous nous placons dans le cadre des methodes de type gradient. Nos travaux portent sur l'acceleration et la regularisation de l'algorithme de reconstruction. L'acceleration resulte d'une part du preconditionnement du systeme par un inverse approche de l'operateur que l'on cherche a inverser, de facon a se ramener a un systeme quasi-symetrique. D'autre part, le systeme preconditionne est resolu par l'algorithme du residu minimal afin d'eviter le passage aux equations normales. La regularisation est accomplie par un filtrage passe-bas des mesures et par une methode de regularisation pouvant etre vue comme une extension de celle de tikhonov-phillips a un probleme quasi-symetrique. Cette methode est rendue spatialement adaptative pour eviter de surlisser dans les regions d'interet. Une approche adaptative basee sur le gradient de l'image est egalement envisagee. La methode de reconstruction est appliquee a la geometrie parallele sur 180 degres et a la geometrie conique. L'imagerie cardiaque est choisie pour evaluer la methode.