Horizontal gene transfer (HGT) is now indisputably the predominant driving force, if not the sole force, behind speciation and the evolution of novelty in bacteria. Of all mechanisms of horizontal gene transfer (HGT), conjugation, the contact-dependent plasmid-mediated transfer of DNA from a bacterial donor to a recipient cell, is probably the most universal. First observed between bacteria, conjugation also mediates gene transfer from bacteria to yeast, plant and even animal cells. The range of environments in which bacteria naturally exchange DNA has not been extensively explored. The interior of the animal cell represents a novel and potentially medically relevant environment for gene transfer. Since most antibiotics are ineffective inside mammalian cells, our cells may be a niche for the evolution of resistance and virulence in invasive pathogens. Invading bacteria accumulate in vacuoles inside human cells, protected from antibiotics. Herein, I demonstrate the ability of intracellular Salmonella typhimurium to meet and exchange plasmid DNA by conjugation within animal cells, revealing the animal intracellular milieu as a permissive environment for gene exchange. This finding evokes a model for the simultaneous dissemination of virulence and antibiotic resistance within a niche protected from both antibiotics and the immune system and extends the variety of environments in which bacteria are known to exchange genes. Unlike conjugation between bacteria, conjugation between bacteria and eukaryotic cells requires the import of transferred DNA into the nucleus before the transferred genes can be expressed and inherited. Plant-cell nuclear transformation by the conjugation system of the Agrobacterium tumefaciens Ti plasmid is believed to be mediated by nuclear localization sequences (NLSs) carried within the proteins that accompany the T-DNA during transfer. Whether NLSs are equally important for transmission of other conjugative plasmids to eukaryotic cells is unknown. Herein, I demonstrate nuclear localization potential within the putative conjugative escort protein TraI of the IncPa plasmid RP4. In contrast, MobA, the putative escort protein from the IncQ plasmid RSF1010, lacked any clear nuclear localization potential. It is therefore likely that specific nuclear localization signals within conjugative proteins are not essential for nuclear transformation per se, although they may assist in efficient plasmid transmission.

Zugl.: München, Univ., Diss., 2004/05

Diss.--Kirchengeschichte--Wien, 1973. / Bibliogr. p. 183-196.

Zugl.: Bamberg, Universiẗat, Zulassungsarb., 1997.

Thèse (M.Ps.)--Université Laval, 2003. / Bibliogr.: f. 14-15. Publié aussi en version électronique.

Thèse (M.Ps.)--Université Laval, 2003. / Bibliogr. Publié aussi en version électronique.

Techn. Hochsch., Diss., 1999--Aachen.

Texte remanié de: Th. doct.--Lettres--Pau, 1992. Titre de soutenance : L'iconographie d'Henri IV dans les ouvrages imprimés de 1589 à 1914. / Bibliogr. p. 539-555. Index.

Made available in DSpace on 2015-12-06T23:03:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2004 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Fundo de Auxílio aos Docentes e Alunos (FADA) / Programa de Apoio a Núcleos de Excelência (PRONEX) / A mitocondria e importante no processo de manutencao da homeostase do calcio, na manutencao do potencial de membrana do neuronio, no processo de apoptose e na formacao de radicais livres (RL). Essas caracteristicas relacionam a mitocondria com a excitotoxicidade vista na epilepsia .Lesoes do DNA mitocondrial (DNAmt) via lesao oxidativa sao vistas em varias doencas sendo presumivel seu) aparecimento na epilepsia pela presenca de RL, ja largamente documentada nessa patologia. Nosso objetivo, no presente estudo, foi avaliar o possivel envolvimento da mitocondria no processo de epileptogenese, no modelo de epilepsia do lobo temporal induzido por pilocarpina. Para tanto, nos propusemos al avaliar o aparecimento de alteracoes do DNAmt, bem como o ocorrencia del disfuncoes de proteinas da cadeia respiratoria. Delecoes ou alteracoes da quantidade das moleculas de DNAmt e disfuncoes da citocromo c oxidade e na succinato desidrogenase foram estudadas em hipocampos de ratos submetidos ao modelo de epilepsia induzida por pilocarpina, com as tecnicas de Southern Blot ,I PCR, histoquimica, Western Blot e Imunohistoquimica. Foram utilizados animais) durante a fase cronica do modelo, quando inicia-se o aparecimento de crises) espontaneas e recorrentes. A analise do DNAmt nao mostrou deplecao ou um aumento de delecoes dos DNAmt nos animais experimentais. Esses dados sugerem que danos do DNAmt nao estejam envolvidos na patogenese da epilepsiaa(au) / Mitochondria have important fuctions in intracellular calcium homeostases, maintenance of neuronal membrane potential, apoptotic signalling and in free radicals production. These features may link mitochondria to a possible role on epilepsy excitotoxicity. Mitochondrial DNA (mtDNA) damage by oxidative lesions are observed in many diseases and it is supposed to occur in epilepsy due to the well stabilished presence of free radicals in this disease. Our aim in this study was to evaluate the possible role of mitochondria in epilepy. The study was performed in the pilocarpine model of temporal lobe epilepsy by studying mtDNA and respiratory chain proteins abnormalities. Deletions or quantitative alterations of mtDNA and dysfuntion of cytocrome c oxidase and succinate dehydrogenase were studied with Southern Blot, polymerase chain reaction (PCR), histochemistry, imunohistochemistry and Western Blot techniques. The animals were in chronic phase of the PILO model of epilepsy when spontaneous and recurrent seizures begin to occur. No mtDNA depletion was observed and increased frequency of mtDNA damage was not detected in epileptic animals. These data do not support the involvement of mtDNA damage in the pathogenesis epilepsy. The expression and distribution of the respiratory chain proteins (COX I, COX IV, SDH) enzymes studied were similar in both groups (control and epileptic animals) in the hippocampus. Furthermore, no difference in COX activity was observed by hystochemistry. The preservation of mtDNA and respiratory chain proteins show a relative maintenance of basal metabolism in epileptic hippocampus. Such data is reinforced by previous study that show no changes in glucose utilization in the chronic phase of this same model of epilepsy. It has been reported that NA+/K+ ATPase is upregulated in epilepsy, and this enzyme is crucial to the maintenance of membrane potential. In addition, this enzyme is highly dependent of mitochondrial ATP production. Considering that NA+/K+ ATPase is upregulated in epilepsy, we would expect a propotional increase in mitochondrial activity to mantain ATPase well function. However, our data do not demonstrate this increase in activity, which could indicate abnormalities in the link between energetic need and mitochondrial function. This hypothesis could be a possible target for future studies. / BV UNIFESP: Teses e dissertações

abstract: Standardized intelligence tests are some of the most widely used tests by psychologists. Of these, clinicians most frequently use the Wechsler scales of intelligence. The most recent version of this test for children is the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV); given the multiple test revisions that have occurred with the WISC, it is essential to address evidence regarding the structural validity of the test; specifically, that the internal structure of the test corresponds with the structure of the theoretical construct being measured. The current study is the first to investigate the factor structure of the WISC-IV across time for the same individuals. Factorial invariance of the WISC-IV was investigated using a group of 352 students eligible for psychoeducational evaluations tested, on average, 2.8 years apart. One research question was addressed: Does the structure of the WISC-IV remain invariant for the same individuals across time? Using structural equation modeling methods for a four-factor oblique model of the WISC-IV, this study found invariance at the configural and weak levels and partial invariance at the strong and strict levels. This indicated that the overall factor structure remained the same at test and retest with equal precision of the factor loadings at both time points. Three subtest intercepts (BD, CD, and SI) were not equivalent across test and retest; additionally, four subtest error variances (BD, CD, SI, and SS) were not equivalent across test and retest. These results indicate that the WISC-IV measures the same constructs equally well across time, and differences in an individual's cognitive profile can be safely interpreted as reflecting change in the underlying construct across time rather than variations in the test itself. This allows clinicians to be more confident in interpretation of changes in the overall cognitive profile of individual's across time. However, this study's results did not indicate that an individual's test scores should be compared across time. Overall, it was concluded that there is partial measurement invariance of the WISC-IV across time, with invariance of all factor loadings, invariance of all but three intercepts, and invariance of all but four item error variances. / Dissertation/Thesis / Ph.D. Educational Psychology 2012