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Clonal diversity and population genetic structure of the grain aphid Sitobion avenae(F.) in central Europe / Klonale Diversität und populationsgenetische Struktur der Großen Getreidelaus Sitobion avenae (F.) in ZentraleuropaReimer, Lars 16 July 2004 (has links)
No description available.
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Asexuelle und sexuelle Reproduktion bei der Vogelkirsche (Prunus avium L.) / Asexual and sexual reproduction in populations of wild cherry (Prunus avium L.)Kownatzki, Dierk 08 February 2001 (has links)
No description available.
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Egr-2 and PD-1 Are Required for Induction and Maintenance of T Cell Anergy: A DissertationBishop, Kenneth D. 13 July 2005 (has links)
The prevalence of diabetes is approaching epidemic proportions worldwide. There is currently no cure for type 1 diabetes, and successful treatment requires constant monitoring of blood sugars and use of exogenous insulin to prevent hyperglycemia. Diabetes will be curable when pancreatic β-islet cells can be transplanted into diabetes patients without requiring long-term immunosuppression. This will require learning more about the induction of functional tolerance, a state that maintains the competence of the immune system to most antigens but protects graft-specific antigens from immune rejection, permitting transplantation. One known mechanism of peripheral tolerance is T cell anergy, a phenotype of hypo-reponsiveness in CD4+ T cells. The focus of this thesis is a description of factors shown to be specific to the induction and maintenance of T cell anergy, whose loss reverses the anergic phenotype, restoring the ability of the cells to proliferate in response to antigen. The first of these is Egr-2, a zinc-finger transcription factor, whose presence is required for the induction of anergy induced in T cell clones by TCR stimulation in the absence of costimulation. Egr-2 is shown to be important to anergy induction but not anergy maintenance. In contrast, a negative costimulation receptor, PD-1, is shown to be necessary for the maintenance of anergy. It is possible that learning more about the genetic factors that orchestrate T cell anergy will prove useful in the development of tolerance-based protocols for organ and tissue transplantation without the use of long-term immunosuppression.
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Fylogeneze krvetvorby obratlovců / Origins of vertebrate hematiopoiesisSvoboda, Ondřej January 2015 (has links)
(ENGLISH) Hematopoiesis is dependent on the actions of hematopoietic stem cells (HSCs). This process is tightly controlled through a complex array of extrinsic and intrinsic factors. Even though the hematopoiesis seems to be well conserved across the disparate vertebrate animals, erythroid and thrombocytic differentiation have changed during the evolution of mammals. Specifically, adult mammalian red blood cells have the unique feature of being enucleated, and mammalian thrombocytes are not individual cells, but fragments of megakaryocytes, instead. It is likely that these enhancements provided a survival advantage to early mammalian species; however, they also bring up the question of evolutionary origin of these cells that studied using zebrafish (Danio rerio) model. First, it was necessary to generate a toolbox of a recombinant cytokines and optimized culture media that allowed us to manipulate zebrafish hematopoietic cells ex vivo in liquid and clonal cultures. Interestingly, teleost species underwent an extra duplication event during their evolution and as a result, two copies (paralogs) of some of the genes are present in zebrafish. This was also the case for majority of the cytokines from our toolbox and here, we provide functional characterization of these paralogs. Strikingly, our results...
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Genomic characterisation and antimicrobial resistance profiles of Listeria monocytogenes isolated from pig farmsMasemola, Puseletso Maselepe 07 1900 (has links)
Listeria monocytogenes is a zoonotic foodborne pathogen, transmissible from the natural
agricultural environment to animals and humans. In recent years, the pig production industry has
experienced a series of monetary losses as a result of the L. monocytogenes outbreak which
threatened the economy of South Africa. This outbreak also had a detrimental effect on the health
system of the country. In South Africa however, there is limited information regarding the genomic
diversity of L. monocytogenes. Therefore, an overview of the genomic diversity of L.
monocytogenes strains circulating at different levels of the pork production chain needs to be
determined so as to be able to identify routes of contamination of the pathogen and thus improve
meat safety. This study was aimed to determine the antimicrobial resistance patterns and
population structure of L. monocytogenes isolated from pig farms in South Africa. Based on wholegenome
sequence analysis, 77 isolates of L. monocytogenes were differentiated into four molecular
serogroups with IIa (45.5%) being the most prevalent followed by IIc (26.0%), IVb (22.1%) and IIb (6.5%). Overall, 11 clonal complexes (CCs) were identified in this study, with the
predominance being observed from; CC204 (23.4%), CC1 (19.5%) and CC2 (16.9%). Genetic
elements associated with biocide, antimicrobial and heavy metal resistance were noted in 24.7 %,
48% and 11.7% of the isolates, respectively. Listeria pathogenicity island 1 and 3 that harbored
clusters of virulence genes were present in 38.8% of the isolates. Five different plasmids were
found in 68.9% of the isolates. This study has given baseline data on the genomic diversity of L.
monocytogenes strains that are associated with biocides, heavy metal and antibiotics resistance
genes. The data again demonstrated the genotypes of L. monocytogenes that are prone to
contaminate the farm environment and possibly cause diseases in animals and humans. / Life and Consumer Sciences / M. Sc. (Life Sciences)
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Caractérisation génotypique des réservoirs viraux qui persistent chez les personnes vivant avec le VIH sous traitement antirétroviralDufour, Caroline 05 1900 (has links)
Les personnes qui vivent avec le VIH (PVVIH) doivent prendre un traitement d’antirétroviraux combinés (ART) pour contrôler la réplication virale et empêcher le développement d’une immunodéficience dont l’issue est fatale. Les ART protègent les cellules saines de l’infection et permettent ainsi de rendre la charge virale plasmatique indétectable. Cependant, l’arrêt des ART entraine presque inévitablement un rebond de la charge virale, puisque le virus n’est jamais complètement éliminé par le système immunitaire. En effet, de multiples cellules infectées, où le virus s’est intégré et demeure dans un état de latence, restent présentes tout au long de la vie des PVVIH. Une partie de ces cellules infectées forme le réservoir compétent pour la réplication. Les provirus responsables du rebond de la charge virale possèdent trois caractéristiques : ils gardent la capacité d’être réactivés (sortie de latence), ils sont génétiquement intacts, et ils peuvent produire de nouvelles particules virales infectieuses. Afin de guérir les PVVIH de l’infection, il faut donc cibler les quelques rares cellules portant un provirus intact et inductible. Pour ce faire, il est impératif de comprendre comment ces cellules sont maintenues pendant les années de ART, de les localiser dans tout l’organisme, et d’identifier ce qui peut les distinguer des autres. Ce sont ces trois aspects que nous avons abordés au cours des travaux de recherche présentés dans cette thèse, autant à l’échelle de la cellule unique que de l’organisme entier. Nos résultats montrent que les provirus compétents pour la réplication persistent dans des lymphocytes T CD4+ mémoires exprimant l’intégrine VLA-4 en grande quantité, que les provirus intacts peuvent subsister au sein de différents compartiments anatomiques, que les provirus inductibles et compétents pour la traduction de la protéine virale p24 sont majoritairement défectifs, et que l’expansion clonale est un mécanisme important qui favorise le maintien du réservoir viral dans le sang et dans les tissus tout en favorisant la diversité phénotypique de ces cellules. / People with HIV (PWH) must take combinational antiretroviral therapy (ART) to control
viral replication and avoid developing fatal immunodeficiency. ART allows achieving undetectable
plasma viral load, and thus protects uninfected cells from HIV. However, ART interruption will
almost inevitably result in a viral rebound since HIV is never completely cleared by the immune
system. Indeed, a group of infected cells, where the virus has integrated and remains in a latent
state, persists throughout the life course of PWH, and some of these cells form the replicationcompetent
reservoir. Proviruses responsible for viral rebound have three characteristics: they can
be induced to exit their latent state, they are genetically intact, and they are able to produce new
infectious viral particles. Therefore, in order to cure PWH, it is essential to target the few cells
with intact and inducible provirus, and to be able to do so, it is imperative to understand how
these cells are maintained during years of ART, to localize them throughout the body, and to
identify what distinguishes them from other cells. These three aspects are the focus of the work
presented in this thesis, whether at the single-cell level or looking through the whole body. Our
results show that replication-competent proviruses persist in memory CD4+ T cells expressing
high levels of the integrin VLA-4, that intact proviruses can persist among various anatomical
compartments, that inducible and translation-competent proviruses are predominantly
defective, and that clonal expansion is an important mechanism that favors the maintenance of
reservoir cells both in the blood and in deep tissues in addition to diversify phenotypically those
cells.
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