33 research outputs found

    Rote Liste und Artenverzeichnis der Schnecken und Muscheln Baden-Württembergs

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    Die vorliegende Veröffentlichung umfasst zwei Grundbausteine. Zum einen die offizielle Rote Liste mit Nennung der Gefährdungskategorien, zum anderen ein revidiertes systematisches Gesamtartenverzeichnis der Mollusken Baden-Württembergs. Die Rote Liste dient zum schnellen Feststellen der jeweiligen Gefährdungskategorien der einzelnen Arten in Baden-Württemberg und ist wie üblich alphabetisch nach Gattungen geordnet. Sehr großer Wert wurde auf die sorgfältige Analyse der Ergebnisse gelegt (Kapitel 7). Das Gesamtartenverzeichnis dient der aktuellen systematischen Einordnung aller Arten, weshalb hier die Taxa im Kontext des wissenschaftlichen Systems der Mollusken aufgeführt werden. Im systematischen Artenverzeichnis soll der momentane Kenntnisstand über die Mollusken Baden-Württembergs in knapper Darstellung zum Ausdruck kommen. Hier sind auch die bekannten Unterarten aufgeführt und es werden zusätzliche Informationen zum Verbreitungstyp, zur Verbreitung (Vorkommen in den Naturräumen 3. Ordnung) sowie zur Ökologie (Zuordnung einzelner Arten zu bestimmten Biotoptypen) gegeben. Mit diesen Zusatzinformationen werden Rote Listen und Artenverzeichnisse zu Gradmessern der Biodiversitätsforschung. In über 130 ‚Anmerkungen‘ werden die entsprechenden Angaben zur Systematik, Verbreitung und Ökologie präzisiert und es wird auf die hierfür zu Grunde liegende Literatur verwiesen. Alle Angaben der Roten Liste sind auch im ausführlichen systematischen Artenverzeichnis enthalten. In beiden Listen sind die Arten mit ihrer laufenden Nummer aufgeführt. Damit ist ein problemloser Wechsel von der Roten Liste zu den Angaben im systematischen Artenverzeichnis gewährleistet. Der Forschungsstand findet sich vielfach in der historischen Literatur, die deshalb eine sorgfältige und kritische Berücksichtigung erfuhr (siehe Anmerkungen und Literaturverzeichnis). Einen unschätzbaren Wert haben in diesem Zusammenhang die zahlreichen Veröffentlichungen David Geyer‘s, die den Beginn der modernen Regionalfaunisik in Baden-Württemberg kennzeichnen. Ein eigenes Kapitel zur Forschungsgeschichte hätte jedoch den vorgegebenen Rahmen dieser Arbeit gesprengt

    (Re)configuration based on model generation

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    Reconfiguration is an important activity for companies selling configurable products or services which have a long life time. However, identification of a set of required changes in a legacy configuration is a hard problem, since even small changes in the requirements might imply significant modifications. In this paper we show a solution based on answer set programming, which is a logic-based knowledge representation formalism well suited for a compact description of (re)configuration problems. Its applicability is demonstrated on simple abstractions of several real-world scenarios. The evaluation of our solution on a set of benchmark instances derived from commercial (re)configuration problems shows its practical applicability.Comment: In Proceedings LoCoCo 2011, arXiv:1108.609

    Introducing LoCo, a Logic for Configuration Problems

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    In this paper we present the core of LoCo, a logic-based high-level representation language for expressing configuration problems. LoCo shall allow to model these problems in an intuitive and declarative way, the dynamic aspects of configuration notwithstanding. Our logic enforces that configurations contain only finitely many components and reasoning can be reduced to the task of model construction.Comment: In Proceedings LoCoCo 2011, arXiv:1108.609

    Lymnaea schirazensis, an Overlooked Snail Distorting Fascioliasis Data: Genotype, Phenotype, Ecology, Worldwide Spread, Susceptibility, Applicability

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    BACKGROUND: Lymnaeid snails transmit medical and veterinary important trematodiases, mainly fascioliasis. Vector specificity of fasciolid parasites defines disease distribution and characteristics. Different lymnaeid species appear linked to different transmission and epidemiological patterns. Pronounced susceptibility differences to absolute resistance have been described among lymnaeid populations. When assessing disease characteristics in different endemic areas, unexpected results were obtained in studies on lymnaeid susceptibility to Fasciola. We undertook studies to understand this disease transmission heterogeneity. METHODOLOGY/PRINCIPAL FINDINGS: A ten-year study in Iran, Egypt, Spain, the Dominican Republic, Mexico, Venezuela, Ecuador and Peru, demonstrated that such heterogeneity is not due to susceptibility differences, but to a hitherto overlooked cryptic species, Lymnaea schirazensis, confused with the main vector Galba truncatula and/or other Galba/Fossaria vectors. Nuclear rDNA and mtDNA sequences and phylogenetic reconstruction highlighted an old evolutionary divergence from other Galba/Fossaria species, and a low intraspecific variability suggesting a recent spread from one geographical source. Morphometry, anatomy and egg cluster analyses allowed for phenotypic differentiation. Selfing, egg laying, and habitat characteristics indicated a migration capacity by passive transport. Studies showed that it is not a vector species (n = 8572 field collected, 20 populations): snail finding and penetration by F. hepatica miracidium occur but never lead to cercarial production (n = 338 experimentally infected). CONCLUSIONS/SIGNIFICANCE: This species has been distorting fasciolid specificity/susceptibility and fascioliasis geographical distribution data. Hence, a large body of literature on G. truncatula should be revised. Its existence has henceforth to be considered in research. Genetic data on livestock, archeology and history along the 10,000-year post-domestication period explain its wide spread from the Neolithic Fertile Crescent. It is an efficient biomarker for the follow-up of livestock movements, a crucial aspect in fascioliasis emergence. It offers an outstanding laboratory model for genetic studies on susceptibility/resistance in F. hepatica/lymnaeid interaction, a field of applied research with disease control perspectives

    Investigating orphan cytochromes P450 from Mycobacterium tuberculosis : the search for potential drug targets

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    Tuberculosis (TB) is a disease that the World Health Organisation (WHO) regards as a global pandemic. There is a great need for new drugs to combat this threat. Drug resistant strains of the causative agent, Mycobacterium tuberculosis (Mtb), have increased the urgency of this quest for novel anti-mycobacterial medicines. Publication of the Mtb genome sequence revealed a large number of cytochrome P450 (CYP) enzymes [Cole, S. T. et al. 1998]. These mono-oxygenase enzymes have been studied for many years and are responsible for metabolic functions in every kingdom of life. Research on the Mtb P450s to date has highlighted several of them as having critcal roles within the organism. CYP121 and CYP128 have been implicated as essential through gene knockout studies. It has been demonstrated that CYP125 is not essential for viability. However, it is part of a gene cluster highly important for Mtb infectivity and virulence. Due to the prospective importance of P450s to Mtb, this group of enzymes is under investigation as a source of novel drug targets. CYP142 was discovered as a potential drug target after it was located to a gene cluster involved in cholesterol catabolism during Mtb dormancy. As part of this PhD project, it was demonstrated that CYP142 performs an almost identical role to that reported for CYP125. These enzymes both perform C27 hydroxylation and carboxylation of the cholesterol side chain. However, variations in the level of oxidation have been identified, dependent upon the redox system with which these P450s are associated. A crystal structure of CYP142 showing high similarity in active site architecture to CYP125 supports the physiological role of CYP142 in cholesterol catabolism. Combining this with in vitro data which demonstrates that CYP142 possesses high affinity for a range of azole anti-fungal agents [Ahmad, Z. et al. 2005, 2006] supports the suggestion that it is a candidate target for the next generation of anti-mycobacterial drugs. CYP144 was highlighted as being important during the latent phase of Mtb growth, a phase that is not targeted by any of the current antimycobacterials. Work performed as part of this PhD has shown that many characteristics of CYP144 are highly comparable to those reported for other MtbP450s. CYP144 shows high affinity and specificity towards many azole molecules. Econazole, clotrimazole and miconazole have repeatedly been shown to bind to MtbP450s, including CYP144 and CYP142, with high affinity and are excellent potential candidates as novel anti-mycobacterial agents. An N-terminally truncated form of CYP144, CYP144-T, has been investigated in the pursuit of a CYP144 crystal structure. It is hoped that this will enable the elucidation of a physiological role for CYP144. Both CYP142 and CYP144 have demonstrated biochemical and biophysical characteristics that contribute to our knowledge of P450 enzymes. This PhD has established that CYP142 exhibits an equilibrium between P450 and P420 species in its CO-bound, ferrous form. A conversion from P420, and stabilisation of P450, upon substrate binding was also demonstrated. CYP144 displays unusual azole coordination characteristics when examined by EPR and removal of the CYP144 gene from Mtb increased sensitivity of the strain to clotrimazole. Studies of these enzymes has advanced knowledge of P450 and Mtb redox chemistry, established roles for the MtbP450 cohort and identified the potential of anti-mycobacterial drugs and associated targets.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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