£\1-antitrypsin¡]£\1-AT¡^is one of over 40-member family of serine protease inhibitors, regulating trypsin and elstase activities by the formation of covalently bound complex. The mechanism of which serpin and enzyme form covalent complex is not clear, but two theorise have been proposed. One is opposite pole theory (OPT) proposed by Huntington et al.¡]2000¡^, suggesting that after serpin is cleaved by serine protease, the P1-linked enzyme is over-swinging about 70

Ethylene plays a key role in square and boll abscission in cotton (Gossypium hirsutum L.). When subjected to stress, cotton plants synthesize higher rates of ethylene which can result in the loss of immature fruit. The ethylene action inhibitor 1- methylcyclopropene (1-MCP) is used in many fruit, vegetable, and floriculture crops to counter the effects of ethylene. Protecting a cotton crop from ethylene through its early reproductive stages may boost yields by increasing fruit retention. A two-year field study was conducted in 2005 and 2006 at the Texas Agricultural Experiment Station in Burleson County, Texas to evaluate the effects of 1-MCP concentration and timing on cotton growth and yield components. The study was designed as a randomized complete block with 4 replications. Three rates of 1-MCP (250, 500, and 1250 g ha-1 of actual product) were applied as a foliar spray at a delivery rate of 93.50 L -1 ha. Each rate was applied at pinhead-square and fourteen days after pinhead-square; pinhead-square, fourteen days after pinheadsquare, and early bloom; early bloom and fourteen days after early bloom; early bloom, fourteen days after early bloom, and twenty-eight days after early bloom. Plant heights, total number of nodes per plant, percent square abscission, nodes above white flower (NAWF), relative chlorophyll content, fruit number, fruit size, and fruit distribution were not affected by 1-MCP. In 2006, electrolytic leakage was significantly increased by two, 250 g ha-1, 1-MCP treatments. In 2005, yield was significantly increased by six of the 1- MCP treatments and suggests an increase in boll retention, boll size, seed number, or seed size. The analysis of yield components conducted through box-mapping, however, failed to explain the observed yield response. In 2006, 1-MCP did not significantly influence yield.

Human immunodeficiency virus type 1 (HIV-1) genome consists of two identical RNAs that appear noncovalently linked near their 5' ends. The 5' untranslated region is called leader region. The 3' part of leader, i.e. nucleotides U200 to G335 in HIV-1 genomic RNA, between the primer binding site and the gag gene, can fold into 3 stem-loops: the kissing-loop domain (KLD) or stem-loop 1 (SL1), the 5' splicing junction hairpin (SD) or SL2 and SL3. The KLD, from nucleotide (nt) 243 to 277, forms a stem-loop (kissing loop hairpin) seated on top of a small stem bulge (stem B and loop B). The kissing-loop hairpin, or dimerization initiation site (DIS) hairpin consists of stem C and loop C. Loop C contains the autocomplementary sequence (ACS) GCGCGC262 or GUGCAC262, also called DIS. / In the kissing-loop model of HIV-1 genome dimerization, HIV-1 RNA dimerization is initiated by base pairing between the ACS of one RNA monomer and that of an adjacent monomer. / To understand the role of the ACS in HIV-1 replication and HIV-1 genomic RNA dimerization, we replaced the central CGCG261 (or tetramer) of the HIV-1 Lai ACS by other tetramers. Genomic RNAs containing the UUAA tetramer (non-HIV-1 tetramer) were half dimeric, but UUAA genome packaging was unaffected. This was the first evidence that genomic RNA dimerization and packaging can be dissociated (Chapter 2). Destroying stem-loop C reduced genomic RNA dimerzation by ~50%, proviral DNA synthesis by ~85%, and reduced viral infectivity by ~3 logarithmic units. Destroying stem-loop B had similar effects on genome dimerization, reverse transcription, and viral infectivity. We also observed that mutations in stem-loop B and in the DIS hairpin were "non additive" (Chapter 2). / The existence of stem-loop C is supported by phylogenetic evidence, while that of stem-loop B is not, namely, its sequence is completely conserved. We investigated the role of stem B and loop B nucleotides in viral replication, and genomic RNA dimerization. The putative CUCG246/CGAG277 duplex was replaced by 9 alternative complementary sequences, 4 likely to base pair in long (~500 nts) RNAs, as assessed by the algorithm mfold. Among the 4 sequences, 3 preserved genome dimerzation, 1 did not significantly inhibit it, and 2 preserved viral replication. We also asked if 9 deletions or nucleotide substitutions within nucleotide 200 to 242 and/or 282 to 335 could influence genome dimerization. Delta200--226 and Delta236--242 genomic RNAs dimerized relatively poorly despite having neutral or positive influences on stem B, loop B and klh folding (Chapter 3). / Mutations within the Matrix, Capsid, p2 and nucleocapsid genes suppress several functional defects caused by KLD destruction. We tested the effect of these suppressor mutations on genome dimerization and infectiousness of viruses bearing moderate to crippling KLD mutations. Our conclusion is that these suppressor mutations can restore genomic RNA dimerization when DIS is weakened, but not when DIS is denatured or the KLD is destroyed (Chapter 4).

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Berlin, Humboldt-Universiẗat, Diss., 2003.

The thermal decomposition of pentene-1 in a static system has been investigated over a temperature range of 470 to 530°C. and a pressure range of 50 to 250 mm. The decomposition was a homogeneous first-order reaction with an average overall activation energy of 52 kcal./mole. The reaction rate was retarded by propylene and by inert gases, but was unaffected by nitric oxide. Free radicals from lead tetraethyl produced an acceleration. The activation energy exhibits a slight increase with increasing initial pressure of pentene. Evidence is presented for a composite reaction mechanism involving both a free-radical chain process and a direct intramolecular rearrangement. . / Science, Faculty of / Chemistry, Department of / Graduate

YB-1 est membre de la superfamille de protéines de choc thermique. YB-1 se lie à l'ARN et l'ADN. Des corrélations entre niveau élevé de YB-1, expression élevée de la P-glycoprotéine MDR1 et un mauvais pronostic ont été faites pour plusieurs types de cancer. Le rôle de YB-1 dans la cancérogenèse peut être soutenu par plusieurs mécanismes: i) l'activation de la transcription; ii) la participation à la réparation de l'ADN; iii) la régulation de la traduction. Les deux premiers modèles supposent une localisation nucléaire de YB-1, et cela malgré le fait que YB-1 est apparaît principalement dans cytoplasme dans des conditions physiologiques et les mécanismes de son accumulation nucléaire restent obscurs. Dans ce travail, nous avons tenté d’identifier les mécanismes qui déclenchent la translocation nucléaire de YB-1. Il est apparu que cette localisation nucléaire dépend principalement du niveau d’ARNm dans le cytoplasme et ainsi d’une transcription active, plutôt que de la présence de lésion à l'ADN nucléaire. A l'inverse, le rôle de YB-1 comme régulateur de la traduction est clairement établi. YB-1 peut influencer la traduction et favoriser la progression du cancer, indépendamment de ses fonctions éventuelles dans le noyau. Nous avons démontré par microscopie à force atomique et à l’aide de méthodes biochimiques, que YB-1 se lie aux ARNm d'une manière coopérative à l’ARNm, ce qui a des conséquences directes sur sa capacité à sélectionner des ARNm spécifiques et à moduler la traduction. Au-delà de ces recherches, nous nous sommes appuyés sur notre maitrise de la biologie de YB-1 pour développer une méthode innovante pour mettre en évidence les interactions protéine-protéine dans le contexte cellulaire. Nous avons ainsi confirmé à l’aide de cette méthode la capacité de YB-1 de former des oligomères en présence d'ARNm, et également révélé son interaction potentielle avec Lin28. / YB-1 is a member of the cold-shock protein superfamily. It binds to both RNA and DNA. Correlations between high level of YB-1, elevated expression of P-glycoprotein MDR1 and poor patient prognosis were made for several types of cancer. The role of YB-1 in cancerogenesis can be accounted by several mechanisms: i) activation of transcription; ii) participation in DNA repair; iii) regulation of translation. The first two proposals imply a nuclear localization for YB-1, despite the fact that it appears mainly in the cytoplasm under physiological conditions and the mechanisms for its nuclear accumulation remain unclear. In this work we attempted to identify the mechanisms that trigger the nuclear translocation of YB-1. It appeared that this depends on the level of mRNA in the cytoplasm and thus on active transcription, rather than on the presence of nuclear DNA damages. In contrast to its function in the nucleus, the role of YB-1 in the regulation of translation was clearly established. YB-1 may therefore orchestrate a translation bias in order to promote cancer progression independently of its putative functions in the nucleus. Here we demonstrated, using atomic force microscopy and biochemical methods, that YB-1 binds mRNA in a highly cooperative manner and this has direct consequences on mRNA selection and following translational modulation. Beyond this research, we took advantage of our knowledge of the biology of YB-1 to develop a new method to detect protein-protein interactions in cellular context, using YB-1 as model protein. Besides the fact that we confirmed ability of YB-1 to make oligomers in the presence of mRNA, we also highlighted its potential interaction with Lin28, using this method.

La sulfatation protéique est une modification post-traductionnelle qui intervient principalement sur les récepteurs cellulaires. Parmi eux, le récepteur CXCR4 est particulièrement étudié en raison de son implication dans de nombreux processus physiopathologiques (réponse immunitaire, infection au VIH). Le domaine extracellulaire de 38 acides aminés de CXCR4 (le peptide P38), contenant trois tyrosines connues pour être sulfatées, est important pour l’interaction avec son ligand spécifique, la chimiokine SDF-1α/CXCL12 (Stromal Cell-Derived Factor-1α). Le rôle de la sulfatation de CXCR4 dans cette interaction est encore méconnu.Le peptide P38 a été synthétisé et sulfaté de façon régiosélective sur toutes les tyrosines (peptides mono-, di- ou tri-sulfatés, soit 7 combinaisons). L’impact du nombre et de la position des groupements sulfate le long du peptide P38 sur son interaction avec SDF-1α a été étudié par électrophorèse capillaire d’affinité (ACE) couplée ou non à la spectrométrie de masse électrospray (ESI-MS). Une interaction entre P38 et SDF-1α a été mise en évidence par ACE. Une augmentation de l’affinité peut être associée à l’augmentation du degré de sulfatation de P38. La stœchiométrie des complexes a ensuite été déterminée en utilisant l’ACE-MS, qui a mis en évidence une majorité de complexes 1:1, quel que soit le peptide étudiéCes travaux ouvrent la voie à l'étude d'une interaction à trois partenaires avec des glycosaminoglycanes. / Sulfation is one of the most important post-translational modifications of proteins. The known sulfated proteins are mostly cell receptors and among them, CXCR4 attracts growing attention because of its involvement in numerous physio-pathological processes (immune response, HIV infection). The 38 amino-acid extracellular domain of CXCR4 (P38 peptide), containing three tyrosine residues known to be sulfated, is important for the interaction with its specific ligand, the SDF-1α/CXCL12 chemokine (Stromal cell-derived factor-1α). The role of sulfation in this interaction remains to be established.The P38 peptide was chemically synthesized and regioselectively sulfated on all the tyrosines (mono-, di- or tri-sulfated peptides, 7 combinations). The impact of both distribution and position of sulfate groups on the interaction between P38 and SDF-1α was studied by affinity capillary electrophoresis (ACE) hyphenated to electrospray mass spectrometry (ESI-MS).An interaction between P38 and SDF-1α was highlighted by ACE. It was strongly enhanced by the increase of P38 sulfation degree. The complex stoichiometry was then determined by ACE-MS, and 1:1 complexes were predominantly obtained, with all the peptides. This work opens the orad to the three-partner interaction studies involving glycosaminoglycans.

No description available.

I denna studie söker vi svar på vilka föreställningar som finns kring 1-till-1-datorer. Vad vet man och vad tror man sig veta? Vilka problem förutser man vid införande av 1 till 1-datorer? Vilka är motiven bakom införandet och de uppfattade vinsterna av 1-till-1- datorer? Fyra personer med olika anknytning till 1-till-1-projekt har intervjuats i en öppen samtalsform i syfte att få ett kvalitativt resultat. Intervjuerna har sedan analyserats med metoden kvalitativ innehållsanalys. De teman och vissa av de kategorier som framkom efter denna analys har sedan diskuterats vidare tillsammans med observation som författarna gjort i sin yrkesroll som gymnasielärare. Resultatet av intervjuerna visar att våra intervjupersoner tänker mycket kring risker och möjligheter samt nya sätt att arbeta. Det uttrycks stor oro inför den förändring som ett 1-till-1-projekt innebär samtidigt som man har positiva förväntningar. Verkligheten är väldigt komplex och utvecklingen går snabbt framåt vilket gör att det är svårt att med enkla samband beskriva den förändring som skett och hur den påverkar undervisningen i skolan.