Kombination von Diiminplatin-Fragmenten mit Catecholato-, Semichinonato- und Olefin-Liganden sowie 4-Hydroxyphenyl-, Ferrocenyl- und Bis(terpyridin)ruthenium–Bausteinen : Festphasensynthese, elektronische Strukturen, Redoxchemie und Photochemie

Im Rahmen dieser Arbeit wurden heteroleptische Diiminplatinkomplexe synthetisiert und charakterisiert. Anhand eines Dichloroplatin(II)-Komplexes wurde eine Festphasensynthese (auf der Basis eines Polystyrol-/Divinylbenzol-Copolymers, mit durch Fluoridionen spaltbarem Silyletherlinker) entwickelt und optimiert. Diese Synthesestrategie wurde anschließend auf die Synthese von ein- und mehrkernigen Catecholatoplatin(II)-Komplexen übertragen. Die Catecholatokomplexe wurden durch Oxidation in die entsprechenden Semichinonatokomplexe überführt, welche durch ESR- und UV/Vis/NIR-Spektroskopie charakterisiert wurden. Sowohl der Dichlorokomplex, als auch die Catecholatokomplexe zeigten in Lösung bei Raumtemperatur keine Lumineszenz. Deprotonierung der Komplexe führte bei den Catecholatokomplexen zu Lumineszenz, nicht jedoch beim Dichlorokomplex. Dieser Befund wurde mit Hilfe von DFT-Rechnungen erklärt, da eine Deprotonierung nur bei den Catecholatokomplexen zu einer Versteifung des Ligandensystems führt und somit möglicherweise eine strahlungslose Relaxation über eine Torsionsmode verringert wird. Durch die Kombination des Diiminfragments mit einem Ferrocenylsubstituenten und anschließender Koordination von Platinfragmenten wurden ein Dichloroplatin(II)-, ein Catecholatoplatin(II)- und ein Olefinplatin(0)-Komplex synthetisiert. Die Redoxeigenschaften dieser Komplexe wurden untersucht und aufgeklärt. Oxidation des Dichlorokomplexes mit [N(p-C6H4Br)3][SbCl6] („Magic Blue“) führte zu dem entsprechenden Ferroceniumkomplex. Einelektronenoxidation des Catecholatokomplexes führte zum Semichinonatokomplex. Ebenso wie beim Olefinkomplex führte eine Dreielektronenoxidation zur Dissoziation der Liganden und dem Entstehen des Dichlorokomplexes. Im ersten Fall wirkte „Magic Blue“ als unschuldiges Oxidationsmittel, im zweiten Fall wurde es jedoch nicht-unschuldig. Dies wurde durch NMR- und UV/Vis/NIR-Spektroskopie belegt. Das Dichlorodiiminplatin(II)-Fragment wurde mit einem photoaktiven Bis(terpyridin)ruthenium(II)-Baustein verknüpft, so dass ein potentieller Photokatalysator erhalten wurde. Tatsächlich wurde durch Bestrahlung in Gegenwart von Wasser und Triethylamin als Protonen- bzw. Elektronenlieferant eine Hydrierung von Tolan zu Stilben beobachtet. Mit Hilfe von DFT-Rechnungen wurden mögliche Wege des photoinduzierten Elektronentransfers bei dieser Reaktion analysiert

Analysis of a normalised expressed sequence tag (EST) library from a key pollinator, the bumblebee Bombus terrestris

<p>Abstract</p> <p>Background</p> <p>The bumblebee, <it>Bombus terrestris </it>(Order Hymenoptera), is of widespread importance. This species is extensively used for commercial pollination in Europe, and along with other <it>Bombus </it>spp. is a key member of natural pollinator assemblages. Furthermore, the species is studied in a wide variety of biological fields. The objective of this project was to create a <it>B. terrestris </it>EST resource that will prove to be valuable in obtaining a deeper understanding of this significant social insect.</p> <p>Results</p> <p>A normalised cDNA library was constructed from the thorax and abdomen of <it>B. terrestris </it>workers in order to enhance the discovery of rare genes. A total of 29'428 ESTs were sequenced. Subsequent clustering resulted in 13'333 unique sequences. Of these, 58.8 percent had significant similarities to known proteins, with 54.5 percent having a "best-hit" to existing Hymenoptera sequences. Comparisons with the honeybee and other insects allowed the identification of potential candidates for gene loss, pseudogene evolution, and possible incomplete annotation in the honeybee genome. Further, given the focus of much basic research and the perceived threat of disease to natural and commercial populations, the immune system of bumblebees is a particularly relevant component. Although the library is derived from unchallenged bees, we still uncover transcription of a number of immune genes spanning the principally described insect immune pathways. Additionally, the EST library provides a resource for the discovery of genetic markers that can be used in population level studies. Indeed, initial screens identified 589 simple sequence repeats and 854 potential single nucleotide polymorphisms.</p> <p>Conclusion</p> <p>The resource that these <it>B. terrestris </it>ESTs represent is valuable for ongoing work. The ESTs provide direct evidence of transcriptionally active regions, but they will also facilitate further functional genomics, gene discovery and future genome annotation. These are important aspects in obtaining a greater understanding of this key pollinator species.</p

Identification of disulfiram as a secretase-modulating compound with beneficial effects on Alzheimer’s disease hallmarks

ADAM10 is a metalloproteinase acting on the amyloid precursor protein (APP) as an alpha-secretase in neurons. Its enzymatic activity results in secretion of a neuroprotective APP cleavage product (sAPPalpha) and prevents formation of the amyloidogenic A-beta peptides, major hallmarks of Alzheimer’s disease (AD). Elevated ADAM10 levels appeared to contribute to attenuation of A-beta-Plaque formation and learning and memory deficits in AD mouse models. Therefore, it has been assumed that ADAM10 might represent a valuable target in AD therapy. Here we screened a FDA-approved drug library and identified disulfiram as a novel ADAM10 gene expression enhancer. Disulfiram increased ADAM10 production as well as sAPP-alpha in SH-SY5Y human neuronal cells and additionally prevented A-beta aggregation in an in vitro assay in a dose-dependent fashion. In addition, acute disulfiram treatment of Alzheimer model mice induced ADAM10 expression in peripheral blood cells, reduced plaque-burden in the dentate gyrus and ameliorated behavioral deficits. Alcohol-dependent patients are subjected to disulfiram-treatment to discourage alcohol-consumption. In such patients, enhancement of ADAM10 by disulfiram-treatment was demonstrated in peripheral blood cells. Our data suggest that disulfiram could be repurposed as an ADAM10 enhancer and AD therapeutic. However, efficacy and safety has to be analyzed in Alzheimer patients in the future

Absence of autoantibodies against correctly folded recombinant fibrillin-1 protein in systemic sclerosis patients

Autoantibodies against short recombinant fragments of fibrillin-1 produced in bacterial expression systems have been found in tight-skin mouse, systemic sclerosis, mixed connective tissue disease, and primary pulmonary hypertension syndrome. In patients with scleroderma, the frequency of anti-fibrillin-1 antibodies was 42% in Caucasians. Until now it has been unclear whether this immune response has a primary function in disease pathogenesis or is a secondary phenomenon. In the present study we analyzed the frequency of autoantibodies against two overlapping recombinant polypeptides spanning the N-terminal and C-terminal halves of human fibrillin-1, which were produced in human embryonic kidney (HEK-293) cells. Correct three-dimensional structures of the recombinant fibrillin-1 polypeptides were shown by electron microscopy and immunoreactivity with antibodies. Screening of fibrillin-1 antibodies was performed in 41 sera from systemic sclerosis patients and in 44 healthy controls with a Caucasian background. Microtiter plates were coated with the recombinant polypeptides of fibrillin-1 and incubated with 1:100 diluted sera. Positive binding was defined as being more than 2 SD above the mean of the control group. ELISAs showed that none of the sera of patients with systemic sclerosis contained autoantibodies against the N-terminal or C-terminal recombinant fibrillin-1 polypeptide. The data show the absence of autoantibodies against recombinant fibrillin-1 protein in Caucasian systemic sclerosis patients. Because the correct three-dimensional folding of the recombinant proteins has been substantiated by several independent methods, we conclude that autoantibodies against correctly folded fibrillin are not a primary phenomenon in the pathogenesis of systemic sclerosis

Novel method for high-throughput colony PCR screening in nanoliter-reactors

We introduce a technology for the rapid identification and sequencing of conserved DNA elements employing a novel suspension array based on nanoliter (nl)-reactors made from alginate. The reactors have a volume of 35 nl and serve as reaction compartments during monoseptic growth of microbial library clones, colony lysis, thermocycling and screening for sequence motifs via semi-quantitative fluorescence analyses. nl-Reactors were kept in suspension during all high-throughput steps which allowed performing the protocol in a highly space-effective fashion and at negligible expenses of consumables and reagents. As a first application, 11 high-quality microsatellites for polymorphism studies in cassava were isolated and sequenced out of a library of 20 000 clones in 2 days. The technology is widely scalable and we envision that throughputs for nl-reactor based screenings can be increased up to 100 000 and more samples per day thereby efficiently complementing protocols based on established deep-sequencing technologie

The salmon louse genome: Copepod features and parasitic adaptations

Copepods encompass numerous ecological roles including parasites, detrivores and phytoplankton grazers. Nonetheless, copepod genome assemblies remain scarce. Lepeophtheirus salmonis is an economically and ecologically important ectoparasitic copepod found on salmonid fish. We present the 695.4 Mbp L. salmonis genome assembly containing ≈60% repetitive regions and 13,081 annotated protein-coding genes. The genome comprises 14 autosomes and a ZZ-ZW sex chromosome system. Assembly assessment identified 92.4% of the expected arthropod genes. Transcriptomics supported annotation and indicated a marked shift in gene expression after host attachment, including apparent downregulation of genes related to circadian rhythm coinciding with abandoning diurnal migration. The genome shows evolutionary signatures including loss of genes needed for peroxisome biogenesis, presence of numerous FNII domains, and an incomplete heme homeostasis pathway suggesting heme proteins to be obtained from the host. Despite repeated development of resistance against chemical treatments L. salmonis exhibits low numbers of many genes involved in detoxification.publishedVersio

Temporal Pattern of ICAM-I Mediated Regulatory T Cell Recruitment to Sites of Inflammation in Adoptive Transfer Model of Multiple Sclerosis

Migration of immune cells to the target organ plays a key role in autoimmune disorders like multiple sclerosis (MS). However, the exact underlying mechanisms of this active process during autoimmune lesion pathogenesis remain elusive. To test if pro-inflammatory and regulatory T cells migrate via a similar molecular mechanism, we analyzed the expression of different adhesion molecules, as well as the composition of infiltrating T cells in an in vivo model of MS, adoptive transfer experimental autoimmune encephalomyelitis in rats. We found that the upregulation of ICAM-I and VCAM-I parallels the development of clinical disease onset, but persists on elevated levels also in the phase of clinical remission. However, the composition of infiltrating T cells found in the developing versus resolving lesion phase changed over time, containing increased numbers of regulatory T cells (FoxP3) only in the phase of clinical remission. In order to test the relevance of the expression of cell adhesion molecules, animals were treated with purified antibodies to ICAM-I and VCAM-I either in the phase of active disease or in early remission. Treatment with a blocking ICAM-I antibody in the phase of disease progression led to a milder disease course. However, administration during early clinical remission aggravates clinical symptoms. Treatment with anti-VCAM-I at different timepoints had no significant effect on the disease course. In summary, our results indicate that adhesion molecules are not only important for capture and migration of pro-inflammatory T cells into the central nervous system, but also permit access of anti-inflammatory cells, such as regulatory T cells. Therefore it is likely to assume that intervention at the blood brain barrier is time dependent and could result in different therapeutic outcomes depending on the phase of CNS lesion development