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Axenic Culture of House-Fly Larvae and the Influence of Stored Nutrients on Adult Dietary Requirements for Survival and ReproductionTaylor, Grace Catherine 05 1900 (has links)
Larvae of the house fly, Musca domestica L. , were reared axenically on semi-synthetic media and their performance both as larvae and as adults was assessed in comparison to that of flies reared on an undefined wheat-bran medium. Three components of a standard sterile casein-base medium, i.e., sodium oleate, RNA and cholesterol, were assessed as to their effects on both the larval and adult stages. All improved larval growth, with cholesterol being essential. It has been substantiated that specific larval nutrient reserves were transferred to the adult. Larval nutrition influenced fecundity through its effect on adult survival and vigour, number of eggs developed, and the adult hormonal system. / Thesis / Master of Science (MSc)
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Effect of Drought, Flooding, and Potassium Stress on the Quantity and Composition of Root Exudates in Axenic CultureHenry, Amelia 01 May 2003 (has links)
Root exudates include important chelating compounds and can change the rhizosphere pH by several units. These changes are essential for nutrient uptake and can also alter solubility of soil contaminants and increase plant uptake. Mild root-zone stress may increase exudation and more severe stress can damage membranes and increase root turnover, all of which increase root-zone carbon. Increased carbon from this rhizodeposition can increase microbial activity, which might help degrade contaminants. We studied the effect of three types of stress on root exudation of crested wheatgrass (Agropyron cristatum): low K+, drought, and flooding. These stresses were compared to two types of controls: 100% NO3- and high NH4+:NO3- ratio. We developed an improved axenic system to keep plants microbe-free for 70 days while analyzing exudates for total organic carbon (TOC) and organic acids. Axenic conditions were confirmed by plate counts of the leachate and microscopic observations of the leachate and roots. Optimal conditions for plant growth were maintained by monitoring temperature, light, humidity, water, O2, CO2, nutrient availability, and root-zone pH. Plants were grown in Ottawa sand that was layered by size to optimize water availability. Total organic carbon released over the 70-day growth period in mg per gram dry plant was 2.6 in the control, 2.3 in the NH4+ treatment, 3.7 in the flood and K+ stress treatments, and 4.4 in the drought treatment, which was the only treatment significantly higher than controls (p = 0.05). TOC and organic acid levels in the exudates peaked before the end of the study. The peak TOC levels, expressed as mg TOC per gram new dry plant mass, were 1.9 in the control, 3.0 in the NH4+ treatment, 2.9 in the flood, and 5.8 in the drought and K+ stress treatments. Organic acids were measured by gas chromatography-mass spectrometry (GC-MS). Malic acid was the predominant organic acid, and accounted for the majority of the TOC in the drought treatment. Oxalic, succinic, fumaric, and malonic acids accounted for less than 10% of the TOC. These data indicate that stress may enhance phytoremediation by changing root-zone exudate composition.
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Towards a Better Understanding of the Metabolism, Physiology, and Ecology of Rumen Protozoa: New Insights from Culturomics and GenomicsPark, Tansol January 2017 (has links)
No description available.
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Avaliação do potencial antileishmania dos compostos naturais isolados ácido úsnico, cumarin, quercetina e reserpina sobre as formas promastigotas e amastigotas de Leishmania ChagasiMartins, Amely Branquinho 19 August 2008 (has links)
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Previous issue date: 2008-08-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Leishmaniases are a complex of infectious parasitic diseases caused by
species of the Leishmania genus. These diseases comprise a large spectrum
of manifestations ranging from localized self-healing cutaneous lesions to
fatal visceral infections. In Brazil, the visceral leishmaniasis is caused by
Leishmania chagasi which affects ca. 2 million people every year with
estimated 90% of cases occurring in Northeastern. Current treatments of
leishmaniasis are based on first line pentavalent antimonials or other drugs
like amphotericin B and pentamidine. Toxicity of those drugs, their high sideeffects,
besides the high cost of treatment, difficulty for administering them
and the surge of resistance are their great drawbacks. These aspects have
stimulated the search for new leishmanicide agents, like the isolation and
identification of natural compounds which could provide new therapeutic
models for the treatment of leishmaniases. It was aimed in the present work
a comparative evaluation of potentially antileishmania natural isolate
compounds and their action on promastigote and amastigote forms of
Leishmania chagasi by observing the cycle of this parasite in vitro. Assays
were carried out with usnic acid, coumarin, quercetin, and reserpine which
showed to have significant antileishmanial activity on promastigote forms of
Leishmania chagasi, presenting IC50 equal to 0.0417; 1.07; 0.271 and 1.7
mM, respectively. It was possible in our experimental conditions of
standardized cultivation of parasites, to establish their life cycle in vitro, by
observing their metamorphosis from promastigote to mastigote. The in vitro
life cycle was characterized by parasite cultivations with establishment of: 1)
lag (initial), log or exponential and stationary stages of promastigotes; 2)
transformation of promastigotes to intracellular amastigotes by infection of
murine macrophages; this step favoured the promastigotes infectivity; and 3)
amastigote isolation and transformation to promastigotes completing the
cycle. Furthermore, it was also possible to establish the in vitro
transformation of promastigotes in axenic amastigotes of Leishmania chagasi
and its use for the evaluation of antileishmanial activity. In this case, the
natural compound usnic acid exhibited antileishmanial activity against axenic
amastigote forms with IC50 of 1,16 mM. It was not observed any similarity of
IC50 on antileishmanial activity of usnic acid and pentamidine between the
axenic amastigote and promastigote forms. This demonstrates that it is
important to characterize the action of compound on each life form of the
parasites. It is concluded that all assayed compounds carried out in this work
had antileishmanial activity on promastigote forms, mainly, and the effect of
concentration was different between promastigote, of lower IC50 values, and
axenic amastigotes forms, of greater IC50 values. / As leishmanioses constituem-se por um complexo de doenças infectoparasitárias,
causadas por parasitas do gênero Leishmania, e apresentam um
espectro de sintomas variando de simples lesões cutâneas de cicatrização
espontânea a lesões viscerais letais. A leishmaniose visceral, causada pela
espécie Leishmania chagasi, no Brasil infecta cerca de duas mil pessoas por
ano, sendo cerca de 90% dos casos no Nordeste. Os tratamentos atuais são
baseados em compostos antimôniais pentavalentes, ou na utilização de
outras drogas como a anfotericina B e a pentamidina. A toxicidade desses
agentes, com efeitos colaterais graves, o alto custo dos tratamentos, as
dificuldades de administração e o surgimento de resistência são grandes
desvantagens, tornando essencial a busca por novos agentes leishmanicidas,
como a identificação de compostos naturais isolados, que podem fornecer
novos modelos terapêuticos no tratamento das leishmanioses. A presente
pesquisa teve como objetivo avaliar comparativamente o potencial
antileishmania de compostos naturais isolados sobre as formas promastigotas
e amastigotas de Leishmania chagasi, estabelecendo o ciclo do parasito in
vitro. Os compostos naturais ensaiados, ácido úsnico, cumarina, quercetina e
reserpina apresentaram significativa atividade antileishmania sobre as formas
promastigotas de Leishmania chagasi, com IC50 igual a 0,0417; 1,07; 0,271 e
1,7 mM respectivamente. Nas condições de cultivo padronizadas no presente
estudo foi possível estabelecer o ciclo de vida in vitro dos parasitos, com
passagem destes pelas duas principais formas de vida: promastigotas e
amastigotas. O ciclo in vitro foi caracterizado pelo cultivo das promastigotas
com estabelecimento: 1) das fases: lag (inicial), log ou exponencial e
estacionária dos parasitos; 2) transformação das formas promastigotas em
amastigotas intracelulares, pela infecção de macrófagos murinos, o que
favoreceu a infectividade das promastigotas; e 3) pelo isolamento das formas
amastigotas e transformação destas em promastigotas novamente,
completando o ciclo. Além disto, foi também possível estabelecer a
transformação in vitro das promastigotas em amastigotas axênicas de L.
chagasi e o cultivo das formas axênicas para ensaios de ação antileishmania
sobre essa forma. Nesse caso, o composto natural isolado ácido úsnico
apresentou atividade antileishmania sobre amastigotas axênicas de L.
chagasi, com IC50 igual a 1,16 mM. Não foi observada similaridade da IC50 na
atividade antileishmania do ácido úsnico e da pentamidina entre as formas
amastigotas axênicas e promastigotas, o que demonstra a importância de
caracterizar a ação dos compostos sobre cada forma de vida dos parasitos.
Conclui-se que os compostos isolados têm atividade antileishmania sobre as
formas promastigotas e o ácido úsnico sobre as formas amastigotas axênicas
de L. chagasi.
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Coxiella burnetii : de la culture aux manifestations cliniques / Coxiella burnetii : from culture to clinical manifestationsEldin, Carole 07 February 2017 (has links)
C. burnetii est une bactérie intracellulaire strcite. Récemment, un milieu axénique, nommé ACCM 2 a été développé, et permet la culture de cette bactérie en atmosphère microaérophile. Nous avons testé si l’ajout d’acide urique dans le milieu de culture pouvait permettre une culture en milieu aérobie. Nous avons observé une croissance de C. burnetii incubée en conditions aérobies dans le milieu ACCM2 enrichi en acide urique. A Cayenne, en Guyane Française, les pneumopathies causées par C. burnetii sont fréquentes et sévères. Nous avons analysé le génome d’une souche isolée à Cayenne. Ce travail a mis en évidence une délétion de 6105 pb intéressant le gène du système de sécrétion de type 1 (T1SS). Cette réduction de génome est probablement impliquée dans l’hypervirulence des souches de Cayenne. Enfin, nous avons testé la sensibilité aux antibiotiques de 6 souches isolées à partir de patients vivant à Cayenne. Ces souches étaient toutes sensibles à la doxycycline et résistantes aux macrolides. Dans une troisième partie nous avons analysé l’apport du TEP scanner dans le diagnostic des infections à C. burnetii. 167 patients atteints d’infections à C. burnetii ont bénéficié d’un TEP scanner. Nous avons retrouvé une proportion élevée de fixations ostéo-articulaires (21) et ganglionnaires (27), et nous avons proposé de nouvelles définitions pour ces localisations. Nous avons ensuite étudié l’impact du traitement chirurgical chez les patients atteints d’infections vasculaires. Une analyse rétrospective de 86 patients atteints d’infections vasculaires a montré que la chirurgie était associée à une diminution de la mortalité à 2,5 ans et à une meilleure évolution sérologique / C. burnetii is an intracellular bacterium. Recently, an axenic medium, named ACCM 2, has been developed and allows the culture of this bacterium in a microaerophilic atmosphere. We tested if the addition of uric acid in the medium could allow an aerobic culture. We observed growth of C. burnetii incubated under aerobic conditions in the ACCM2 medium enriched with uric acid. In Cayenne, French Guiana, pneumonia caused by C. burnetii are frequent and severe. We analyzed the genome of a strain from Cayenne. This work revealed a 6105 bp deletion in the gene of the type 1 secretion system (T1SS). This genome reduction is probably involved in the hypervirulence of Cayenne strains. Finally, we tested the antibiotic suceptibility of 6 strains isolated from patients living in Cayenne. These strains were all susceptible to doxycycline and resistant to macrolides. In a third part we analyzed the contribution of PET scanner in the diagnosis of C. burnetii infections. 167 patients with C. burnetii infections benefited from a PET scan. We found a high proportion of osteo-articular (21) and lymphadenitis (27) fixations, and we proposed new definitions for these locations. We then investigated the impact of surgical treatment in patients with vascular infections. A retrospective analysis of 86 patients with vascular infections showed that surgery was associated with a lower mortality at 2.5 years and a better serological outcome
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