Arthrobacter belongs to an underexplored genus of antimicrobial-producing bacteria. All species in this genus are Gram-positive and commonly isolated from soil and marine sources. This genus is known to exhibit metabolic versatility greatly influenced by environmental conditions and nutrition. Arthrobacter sp. strain TAJX1902 isolated from an unknown soil sample is shown to inhibit a filamentous indicator type bacterium. It produced a few bioactive secondary metabolites in rich medium (RM) broth and agar culture. TAJX1902 crude extract was primarily fractionated using a Sephedex LH-20 column. Further purification achieved via Flash Column Chromatography and Preparative Thin layer Chromatography yielded five prominent crude products. The scope of this project is to fully determine the structure of potential novel antibacterial compounds from TAJX1902 via spectroscopic techniques including full 2D-NMR spectroscopic data set in combination with High-Resolution Mass Spectroscopy (HRMS). The research work is currently underway towards the final purification of the compounds using High-Performance Liquid Chromatography (HPLC) method to enable structural determination and evaluation of their antimicrobial activities.

Bioactive glasses exhibit unique characteristics as a material for bone tissue engineering. Unfortunately, their extensive application for the repair of load-bearing bone defects is still limited by low mechanical strength and fracture toughness. The main aim of this work was two-fold: the reinforcement of brittle Bioglass®-based porous scaffolds and the production of bulk Bioglass® samples exhibiting enhanced mechanical properties. For the first task, scaffolds were coated by composite coating constituted by polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC). The addition of PVA/MFC coating led to a 10 fold increase of compressive strength and a 20 fold increase of tensile strength in comparison with non-coated scaffolds. SEM observations of broken struts surfaces proved the reinforcing and toughening mechanism of the composite coating which was ascribed to crack bridging and fracture of cellulose fibrils. The mechanical properties of the coating material were investigated by tensile testing of PVA/MFC stand–alone specimens. The stirring time of the PVA/MFC solution came out as a crucial parameter in order to achieve a more homogeneous dispersion of the fibres and consequently enhanced strength and stiffness. Numerical simulation of a PVA coated Bioglass® strut revealed the infiltration depth of the coating until the crack tip as the most effective criterion for the struts strengthening. Contact angle and linear viscosity measurements of PVA/MFC solutions showed that MFC causes a reduction in contact angle and a drastic increase in viscosity, indicating that a balance between these opposing effects must be achieved. Concerning the production of bulk samples, conventional furnace and spark plasma sintering technique was used. Spark plasma sintering performed without the assistance of mechanical pressure and at heating rates ranging from 100 to 300°C /min led to a material having density close to theoretical one and fracture toughness nearly 4 times higher in comparison with conventional sintering. Fractographic analysis revealed the crack deflection as the main toughening mechanisms acting in the bulk Bioglass®. Time–dependent crack healing process was also observed. The further investigation on the non-equilibrium phases crystallized is required. All obtained results are discussed in detail and general recommendations for scaffolds with enhanced mechanical resistance are served.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21004号 / 医博第4350号 / 新制||医||1028(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 戸口田 淳也, 教授 妻木 範行, 教授 開 祐司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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京都大学 / 新制・論文博士 / 博士(工学) / 乙第13456号 / 論工博第4196号 / 新制||工||1770(附属図書館) / (主査)教授 中村 正治, 教授 大江 浩一, 教授 村田 靖次郎 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

<p>  </p> <p>A concise and scalable total synthesis of the therapeutically relevant methyl ester of the prostaglandin D₂ metabolite, tricyclic-PGDM, was accomplished in 8 steps from a known and easily accessed cyclopentene-diol derivative. The route features three key transition metal catalyzed steps. These steps include: a nickel catalyzed Ueno-Stork type dicarbofunctionalization which generates two consecutive stereocenters on the central cyclopentane core, a late-stage palladium-catalyzed carbonylative oxaspirolactonization, and a <em>Z</em>-selective cross metathesis to introduce the <em>Z</em>-butenoate side chain- a motif difficult to introduce through traditional protocols and which caused significant issues in the previous total syntheses of tricyclic-PGDM. Through this route, we have accumulated 75 mg of material for an ¹⁸O tricyclic-PGDM clinical assay which previously suffered from a material shortage. In addition to completing the synthesis, we generalized the <em>Z</em>-selective cross metathesis and nickel catalyzed Ueno-Stork protocols to numerous other substrates further demonstrating the utility of these transformations. </p> <p><br></p> <p>Protein arginine methyltransferases (PRMTs) catalyze the transfer of methyl groups from the cofactor SAM to arginine residues on various cytosolic and nuclear proteins. Of the nine members of the PRMT family, PRMT5 has been the most extensively studied and has been shown to regulate processes such as the DNA damage response, cell proliferation, and mRNA translation. Although numerous pathways have been identified that regulate PRMT5 activity, the cytosolic protein MEP50 has been identified as a key regulator in many diseases. PRMT5 and MEP50 interact to form a hetero-octameric complex, which can modulate the activity of PRMT5 for many cellular processes. Two new generations of PRMT5:MEP50 inhibitors were strategically designed and synthesized, which do not suffer from chemical instability like our previously most potent analogues. Our best compounds have IC₅₀ values ranging from 512 to 2.5 nM in LNCaP cells, and were confirmed to target the PRMT5:MEP50 interaction through BiFC analysis.</p>

The Streptomyces are invaluable as a natural source of antibiotics and other bioactive compounds used in medicine and agriculture. S. coelicolor is the model streptomycete, and is studied for its complex secondary metabolism and multicellular life cycle. The subject of this work is bldB, a gene essential for development and antibiotic production in S. coelicolor, and one of its many homologues, located in the abaA antibiotic regulatory locus. The aim was to study the transcriptional regulation of bldB using a luminescent reporter, and investigate the role of each of the genes in the abaA cluster in regulation of antibiotic production, in order to understand the function and mechanism of action of bldB and its homologues. Individual deletion of each of the four genes in the abaA cluster resulted in varying effects on production of the antibiotic CDA. The bldB homologue, SCO0703, was shown to be a positive regulator of CDA, as the null mutant was severely defective in CDA production. It was found that bldB is expressed in most other bld developmental mutants, with the exception of bldD. There was no direct interaction observed between BldD and the bldB promoter, and possible mechanisms of indirect regulation are proposed. / Thesis / Master of Science (MSc)

Fisetin, a flavanol with anti-inflammatory, anti-cancer, and anti-aging properties, has shown promise for reducing fat accumulation in tissue culture and animal models. This plant sourced compound has limited studies supporting its effects on fat accumulation. Therefore, this study was completed to determine fisetin’s role in fat reduction along with its mechanism of action using Caenorhabditis elegans. C. elegans is a small roundworm with roughly 65% of its genes being conserved in humans related to disease. In this study, 100 and 200 µM fisetin has shown to reduce fat accumulation in wild-type worms. Body size, locomotion, and pumping rate were assessed in wild-type worms to determine if fisetin modified worm size, speed, and feed behavior, respectively. Mutant strains were tested to elucidate a potential pathway, of which tub-1 knockout mutants failed to reduce fat accumulation after fisetin treatment, suggesting this gene’s involvement. Gene expression of tub-1 was not altered by fisetin treatment, suggesting potential post-transcriptional regulation of fisetin. This study serves as an introduction to fisetin’s fat reducing effects via a tub-1 dependent mechanism.

No / The structural and functional diversity of lipids accounts for their involvement into a wide range of homeostatic processes and disease states, including lifestyle-related diseases as well as genetic conditions. Challenges presented by this diversity have been addressed to a great extent by the development of lipidomics, a platform that makes possible the detailed profiling and characterisation of lipid species present in any cell, organelle, tissue or body fluid, and allows for a wider appreciation of the biological role of lipid networks. Progress in the field of lipidomics has been greatly facilitated by recent advances in MS and includes a range of analytical platforms supporting applications spanning from qualitative and quantitative assessment of multiple species to lipid imaging. Here we review these MS techniques currently in routine use in lipidomics, alongside with new ones that have started making an impact in the field. Recent applications in health, disease and nutrition-related questions will also be discussed with a view to convey the importance of lipidomics contributions to biosciences and food technology.

L'immobilisation de biomacromolécules à la surface de polymères peu réactifs est une voie de synthèse de nanomatériaux qui fait actuellement l'objet de nombreuses recherches pour le développement d'applications biologiques et médicales. Nous avons synthétisé de nouveaux nanomatériaux à base de polypropylène (PP) greffé par des dendrimères de lysine (DGL). Les DGL sont parfaitement solubles dans l'eau, biocompatibles, polycationiques à pH neutre et leur structure dendritique particulière font d'eux des macromolécules de plus en plus étudiées en interactions avec les milieux biologiques. Différents traitements par plasma ont permis de fonctionnaliser la surface du PP et plusieurs stratégies ont été adoptées pour greffer les DGL sous forme de monocouche, multicouche ou à partir de brosses de polymères : le greffage direct, les polymérisations non contrôlée et contrôlée de type RAFT associées au plasma d'iode et à la chimie click de surface. L'aptitude des matériaux PP fonctionnalisés par le DGL à interagir avec les milieux biologiques a été étudiée, en particulier l'immobilisation de l'ATP et le comportement vis-à-vis des bactéries et des virus. Les propriétés de ces nanomatériaux sont liées à la réactivité des groupements amine des DGL ainsi qu'à la structure régulière et sphérique des dendrimères. Les résultats obtenus ouvrent de nombreuses applications potentielles pour le traitement des eaux, le diagnostic et la prévention du développement des micro-organismes. / Great attention has been focused these last years on tailoring polymer surfaces by immobilizationof suitable molecules for biological and medical applications such as tissue engineering, drug delivery systems, antibacterial supports, and biosensors. In that context, we report the preparation of an original hybrid material based on polypropylene and poly-L-Lysine dendrigrafts (DGL) which are perfectly water soluble, and biocompatible. First, activation of the polypropylene surface (PP) was achieved using plasma treatment. Then, several strategies have been developed to graft DGL onto the PP surface such as (i) direct grafting of DGL after surface activation, (ii) the use of conventional radical polymerization or (iii) RAFT polymerization of monomers from the PP surface. The last methodology favored the increase of the DGL grafts density onto the surface. The ability of PP surface functionalized with DGL to interact with biological media was studied and the modified surfaces open the way to many potential applications in water treatment, diagnosis and prevention of the development of microorganisms.