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Search Results: 1 - 10 of 401509 matches for " Peer M. Schenk "
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High Lipid Induction in Microalgae for Biodiesel Production
Kalpesh K. Sharma,Holger Schuhmann,Peer M. Schenk
Energies , 2012, DOI: 10.3390/en5051532
Abstract: Oil-accumulating microalgae have the potential to enable large-scale biodiesel production without competing for arable land or biodiverse natural landscapes. High lipid productivity of dominant, fast-growing algae is a major prerequisite for commercial production of microalgal oil-derived biodiesel. However, under optimal growth conditions, large amounts of algal biomass are produced, but with relatively low lipid contents, while species with high lipid contents are typically slow growing. Major advances in this area can be made through the induction of lipid biosynthesis, e.g., by environmental stresses. Lipids, in the form of triacylglycerides typically provide a storage function in the cell that enables microalgae to endure adverse environmental conditions. Essentially algal biomass and triacylglycerides compete for photosynthetic assimilate and a reprogramming of physiological pathways is required to stimulate lipid biosynthesis. There has been a wide range of studies carried out to identify and develop efficient lipid induction techniques in microalgae such as nutrients stress (e.g., nitrogen and/or phosphorus starvation), osmotic stress, radiation, pH, temperature, heavy metals and other chemicals. In addition, several genetic strategies for increased triacylglycerides production and inducibility are currently being developed. In this review, we discuss the potential of lipid induction techniques in microalgae and also their application at commercial scale for the production of biodiesel.
Microalgae Isolation and Selection for Prospective Biodiesel?Production
Van Thang Duong,Yan Li,Ekaterina Nowak,Peer M. Schenk
Energies , 2012, DOI: 10.3390/en5061835
Abstract: Biodiesel production from microalgae is being widely developed at different scales as a potential source of renewable energy with both economic and environmental benefits. Although many microalgae species have been identified and isolated for lipid production, there is currently no consensus as to which species provide the highest productivity. Different species are expected to function best at different aquatic, geographical and climatic conditions. In addition, other value-added products are now being considered for commercial production which necessitates the selection of the most capable algae strains suitable for multiple-product algae biorefineries. Here we present and review practical issues of several simple and robust methods for microalgae isolation and selection for traits that maybe most relevant for commercial biodiesel production. A combination of conventional and modern techniques is likely to be the most efficient route from isolation to large-scale cultivation.
Culture-Independent Molecular Tools for Soil and Rhizosphere Microbiology
Vivian A. Rincon-Florez,Lilia C. Carvalhais,Peer M. Schenk
Diversity , 2013, DOI: 10.3390/d5030581
Abstract: Soil microbial communities play an important role in plant health and soil quality. Researchers have developed a wide range of methods for studying the structure, diversity, and activity of microbes to better understand soil biology and plant-microbe interactions. Functional microbiological analyses of the rhizosphere have given new insights into the role of microbial communities in plant nutrition and plant protection against diseases. In this review, we present the most commonly used traditional as well as new culture-independent molecular methods to assess the diversity and function of soil microbial communities. Furthermore, we discuss advantages and disadvantages of these techniques and provide a perspective on emerging technologies for soil microbial community profiling.
Ethylene Response Factor 6 Is a Regulator of Reactive Oxygen Species Signaling in Arabidopsis
Nasser Sewelam, Kemal Kazan, Skye R. Thomas-Hall, Brendan N. Kidd, John M. Manners, Peer M. Schenk
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070289
Abstract: Reactive oxygen species (ROS) are produced in plant cells in response to diverse biotic and abiotic stresses as well as during normal growth and development. Although a large number of transcription factor (TF) genes are up- or down-regulated by ROS, currently very little is known about the functions of these TFs during oxidative stress. In this work, we examined the role of ERF6 (ETHYLENE RESPONSE FACTOR6), an AP2/ERF domain-containing TF, during oxidative stress responses in Arabidopsis. Mutant analyses showed that NADPH oxidase (RbohD) and calcium signaling are required for ROS-responsive expression of ERF6. erf6 insertion mutant plants showed reduced growth and increased H2O2 and anthocyanin levels. Expression analyses of selected ROS-responsive genes during oxidative stress identified several differentially expressed genes in the erf6 mutant. In particular, a number of ROS responsive genes, such as ZAT12, HSFs, WRKYs, MAPKs, RBOHs, DHAR1, APX4, and CAT1 were more strongly induced by H2O2 in erf6 plants than in wild-type. In contrast, MDAR3, CAT3, VTC2 and EX1 showed reduced expression levels in the erf6 mutant. Taken together, our results indicate that ERF6 plays an important role as a positive antioxidant regulator during plant growth and in response to biotic and abiotic stresses.
Activation of the Jasmonic Acid Plant Defence Pathway Alters the Composition of Rhizosphere Bacterial Communities
Lilia C. Carvalhais, Paul G. Dennis, Dayakar V. Badri, Gene W. Tyson, Jorge M. Vivanco, Peer M. Schenk
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056457
Abstract: Jasmonic acid (JA) signalling plays a central role in plant defences against necrotrophic pathogens and herbivorous insects, which afflict both roots and shoots. This pathway is also activated following the interaction with beneficial microbes that may lead to induced systemic resistance. Activation of the JA signalling pathway via application of methyl jasmonate (MeJA) alters the composition of carbon containing compounds released by roots, which are implicated as key determinants of rhizosphere microbial community structure. In this study, we investigated the influence of the JA defence signalling pathway activation in Arabidopsis thaliana on the structure of associated rhizosphere bacterial communities using 16S rRNA gene amplicon pyrosequencing. Application of MeJA did not directly influence bulk soil microbial communities but significant changes in rhizosphere community composition were observed upon activation of the jasmonate signalling pathway. Our results suggest that JA signalling may mediate plant-bacteria interactions in the soil upon necrotrophic pathogen and herbivorous insect attacks.
Isolation and Evaluation of Oil-Producing Microalgae from Subtropical Coastal and Brackish Waters
David K. Y. Lim, Sourabh Garg, Matthew Timmins, Eugene S. B. Zhang, Skye R. Thomas-Hall, Holger Schuhmann, Yan Li, Peer M. Schenk
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040751
Abstract: Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species.
Klinische Studien/Klinische Praxis: Corifollitropin alpha (Elonva) in der t glichen Praxis Erfahrungen aus dem Kinderwunschinstitut
Schenk M
Journal für Gyn?kologische Endokrinologie , 2013,
Das Hepatopulmonale Syndrom
Schenk P,Müller C
Journal für Gastroenterologische und Hepatologische Erkrankungen , 2004,
Abstract: Das Hepatopulmonale Syndrom kommt als Komplikation einer Reihe von Lebererkrankungen vor. Es ist durch die typische Trias Lebererkrankung (meist Zirrhose), intrapulmonale Vasodilatation auf kapill rem und pr kapill rem Niveau und pathologische arterielle Oxygenierung charakterisiert. Es kann mit anderen, prim r kardialen und pulmonalen Erkrankungen koexistieren. Neben diffuser pulmonaler Vasodilatation nahe der Gasaustauschzone (mit verminderter H moglobin-Oxygenierung im zentralen kapill ren Blutstrom) kommt es weit seltener zu lokalisierten, arterioven sen Anastomosen. Als hauptverantwortlicher Mediator wird vermehrt produziertes Stickoxid angenommen. Die Diagnose beruht einerseits auf einem erniedrigten PaO2 oder einer erh hten AaDO2 in der arteriellen Blutgasanalyse, andererseits auf einer positiven Kontrastechokardiographie oder positiven Perfusionsszintigraphie mit 99mTechnetium-makroaggregiertem Albumin. Die Pr valenz betr gt bei Patienten mit Zirrhose 5 32 %, das Mortalit tsrisiko ist erh ht (unabh ngiger Risikoparameter). Die einzige anerkannte Therapie stellt die Lebertransplantation dar.
Fixed point theorems using reciprocal continuity in 2 non Archimedean Menger PM-spaces
S. Ranjeth Kumar,Loganathan,M. Peer Mohamed
International Journal of Contemporary Mathematical Sciences , 2012,
A Framework for Agent-based Human Interaction Support
Axel Bürkle,Wilmuth Müller,Uwe Pfirrmann,Manfred Schenk
Journal of Systemics, Cybernetics and Informatics , 2008,
Abstract: In this paper we describe an agent-based infrastructure for multimodal perceptual systems which aims at developing and realizing computer services that are delivered to humans in an implicit and unobtrusive way. The framework presented here supports the implementation of human-centric context-aware applications providing non-obtrusive assistance to participants in events such as meetings, lectures, conferences and presentations taking place in indoor "smart spaces". We emphasize on the design and implementation of an agent-based framework that supports "pluggable" service logic in the sense that the service developer can concentrate on coding the service logic independently of the underlying middleware. Furthermore, we give an example of the architecture's ability to support the cooperation of multiple services in a meeting scenario using an intelligent connector service and a semantic web oriented travel service.
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