TY - JOUR A1 - Unuabonah, Emmanuel I. A1 - Kolawole, Matthew O. A1 - Agunbiade, Foluso O. A1 - Omorogie, Martins O. A1 - Koko, Daniel T. A1 - Ugwuja, Chidinma G. A1 - Ugege, Leonard E. A1 - Oyejide, Nicholas E. A1 - Günter, Christina A1 - Taubert, Andreas T1 - Novel metal-doped bacteriostatic hybrid clay composites for point-of-use disinfection of water JF - Journal of Environmental Chemical Engineering N2 - This study reports the facile microwave-assisted thermal preparation of novel metal-doped hybrid clay composite adsorbents consisting of Kaolinite clay, Carica papaya seeds and/or plantain peels (Musa paradisiaca) and ZnCl2. Fourier Transformed IR spectroscopy, X-ray diffraction, Scanning Electron Microscopy and Brunauer-Emmett-Teller (BET) analysis are employed to characterize these composite adsorbents. The physicochemical analysis of these composites suggests that they act as bacteriostatic rather than bacteriacidal agents. This bacterostactic action is induced by the ZnO phase in the composites whose amount correlates with the efficacy of the composite. The composite prepared with papaya seeds (PS-HYCA) provides the best disinfection efficacy (when compared with composite prepared with Musa paradisiaca peels-PP-HYCA) against gram-negative enteric bacteria with a breakthrough time of 400 and 700 min for the removal of 1.5 x10(6) cfu/mL S. typhi and V. cholerae from water respectively. At 10(3) cfu/mL of each bacterium in solution, 2 g of both composite adsorbents kept the levels the bacteria in effluent solutions at zero for up to 24 h. Steam regeneration of 2 g of bacteria-loaded Carica papaya prepared composite adsorbent shows a loss of ca. 31% of its capacity even after the 3rd regeneration cycle of 25 h of service time. The composite adsorbent prepared with Carica papaya seeds will be useful for developing simple point-of-use water treatment systems for water disinfection application. This composite adsorbent is comparatively of good performance and shows relatively long hydraulic contact times and is expected to minimize energy intensive traditional treatment processes. KW - Kaolinite KW - Composites KW - Bacteria KW - Breakthrough time KW - Regeneration Y1 - 2017 U6 - https://doi.org/10.1016/j.jece.2017.04.017 SN - 2213-3437 VL - 5 SP - 2128 EP - 2141 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Caron, Maria Mercedes A1 - De Frenne, Pieter A1 - Brunet, Jörg A1 - Chabrerie, Olivier A1 - Cousins, Sara A. O. A1 - Decocq, Guillaume A1 - Diekmann, Martin A1 - Graae, Bente Jessen A1 - Heinken, Thilo A1 - Kolb, Annette A1 - Lenoir, Jonathan A1 - Naaf, Tobias A1 - Plue, Jan A1 - Selvi, Federico A1 - Wulf, Monika A1 - Verheyen, Kris T1 - Divergent regeneration responses of two closely related tree species to direct abiotic and indirect biotic effects of climate change JF - Forest ecology and management N2 - Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change. (C) 2015 Elsevier B.V. All rights reserved. KW - Acer KW - Regeneration KW - Latitudinal gradient KW - Temperature KW - Precipitation KW - Competition Y1 - 2015 U6 - https://doi.org/10.1016/j.foreco.2015.01.003 SN - 0378-1127 SN - 1872-7042 VL - 342 SP - 21 EP - 29 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Unuabonah, Emmanuel I. A1 - El-Khaiary, Mohammad I. A1 - Olu-Owolabi, Bamidele I. A1 - Adebowale, Kayode O. T1 - Predicting the dynamics and performance of a polymer-clay based composite in a fixed bed system for the removal of lead (II) ion JF - Chemical engineering research and design N2 - A polymer-clay based composite adsorbent was prepared from locally obtained kaolinite clay and polyvinyl alcohol. The composite adsorbent was used to remove lead (II) ions from aqueous solution in a fixed bed mode. The increase in bed height and initial metal ion concentration increased the adsorption capacity of lead (II) and the volume of aqueous solution treated at 50% breakthrough. However, the adsorption capacity was reduced by almost 16.5% with the simultaneous presence of Ca2+/Pb2+ and Na+/Pb2+ in the aqueous solution. Regeneration of the adsorbent with 0.1 M of HCl also reduced its adsorption capacity to 75.1%. Adsorption of lead (II) ions onto the polymer-clay composite adsorbent in the presence of Na+ and Ca2+ electrolyte increased the rate of mass transfer, probably due to competition between cationic species in solution for adsorption sites. Regeneration further increased the rate of mass transfer as a result of reduced adsorption sites after the regeneration process. The length of the mass transfer zone was found to increase with increasing bed height but did not change with increasing the initial metal ion concentration. The models of Yoon-Nelson, Thomas, and Clark were found to give good fit to adsorption data. On the other hand, Bohart-Adams model was found to be a poor predictor for the column operation. The polymer-clay composite adsorbent has a good potential for the removal of lead (II) ions from highly polluted aqueous solutions. KW - Fixed bed KW - Adsorption models KW - Polymer-clay composite KW - Regeneration KW - Breakthrough KW - Mass transfer zone Y1 - 2012 U6 - https://doi.org/10.1016/j.cherd.2011.11.009 SN - 0263-8762 VL - 90 IS - 8 SP - 1105 EP - 1115 PB - Inst. of Electr. and Electronics Engineers CY - Rugby ER - TY - THES A1 - Ahmad Abadi, Mohammad T1 - Development and application of novel genetic transformation technologies in maize (Zea mays L.) T1 - Entwicklung und Anwendung neuer genetischer Transformationstechnologien im Mais (Zea Mays L.) N2 - Plant genetic engineering approaches are of pivotal importance to both basic and applied research. However, rapid commercialization of genetically engineered crops, especially maize, raises several ecological and environmental concerns largely related to transgene flow via pollination. In most crops, the plastid genome is inherited uniparentally in a maternal manner. Consequently, a trait introduced into the plastid genome would not be transferred to the sexually compatible relatives of the crops via pollination. Thus, beside its several other advantages, plastid transformation provides transgene containment, and therefore, is an environmentally friendly approach for genetic engineering of crop plants. Reliable in vitro regeneration systems allowing repeated rounds of regeneration are of utmost importance to development of plastid transformation technologies in higher plants. While being the world’s major food crops, cereals are among the most difficult-to-handle plants in tissue culture which severely limits genetic engineering approaches. In maize, immature zygotic embryos provide the predominantly used material for establishing regeneration-competent cell or callus cultures for genetic transformation experiments. The procedures involved are demanding, laborious and time consuming and depend on greenhouse facilities. In one part of this work, a novel tissue culture and plant regeneration system was developed that uses maize leaf tissue and thus is independent of zygotic embryos and greenhouse facilities. Also, protocols were established for (i) the efficient induction of regeneration-competent callus from maize leaves in the dark, (ii) inducing highly regenerable callus in the light, and (iii) the use of leaf-derived callus for the generation of stably transformed maize plants. Furthermore, several selection methods were tested for developing a plastid transformation system in maize. However, stable plastid transformed maize plants could not be yet recovered. Possible explanations as well as suggestions for future attempts towards developing plastid transformation in maize are discussed. Nevertheless, these results represent a first essential step towards developing chloroplast transformation technology for maize, a method that requires multiple rounds of plant regeneration and selection to obtain genetically stable transgenic plants. In order to apply the newly developed transformation system towards metabolic engineering of carotenoid biosynthesis, the daffodil phytoene synthase (PSY) gene was integrated into the maize genome. The results illustrate that expression of a recombinant PSY significantly increases carotenoid levels in leaves. The beta-carotene (pro-vitamin A) amounts in leaves of transgenic plants were increased by ~21% in comparison to the wild-type. These results represent evidence for maize to have significant potential to accumulate higher amounts of carotenoids, especially beta-carotene, through transgenic expression of phytoene synthases. Finally, progresses were made towards developing transformation technologies in Peperomia (Piperaceae) by establishing an efficient leaf-based regeneration system. Also, factors determining plastid size and number in Peperomia, whose species display great interspecific variation in chloroplast size and number per cell, were investigated. The results suggest that organelle size and number are regulated in a tissue-specific manner rather than in dependency on the plastid type. Investigating plastid morphology in Peperomia species with giant chloroplasts, plasmatic connections between chloroplasts (stromules) were observed under the light microscope and in the absence of tissue fixation or GFP overexpression demonstrating the relevance of these structures in vivo. Furthermore, bacteria-like microorganisms were discovered within Peperomia cells, suggesting that this genus provides an interesting model not only for studying plastid biology but also for investigating plant-microbe interactions. N2 - Pflanzliche Gentechnik spielt sowohl in der Grundlagenforschung als auch der Biotechnologie eine große Rolle. Allerdings bringt die landwirtschaftliche Nutzung gentechnisch veränderter Pflanzen (GM) ökologische Umweltrisiken mit sich, wie z.B. die Kreuzung GM Pflanzen mit sexuell kompatiblen Verwandten durch Fremdbestäubung. Gegenüber den Kerntransformanden haben Plastidtransformanden für die biotechnologische Nutzung große Vorteile, unter anderem da die Vererbung des Plastidgenoms bei höheren Angiospermen ausschließlich maternal geschieht. Somit kann ein Gentransfer transplastomischer Pflanzen über Pollen ausgeschlossen werden. Zuverlässige in-vitro-Regenerationssysteme, die wiederholte Regenerationsrunden erlauben, sind von großem Wert für die Etablierung der Plastidentransformationstechnologie. Trotz Sein die Hauptgetreidenahrungsmittel der Welt, Zerealie Pflanzen gehören zu schwierigsten in der Gewebekultur zu handeln, die Annäherungen der genetischen Technik streng begrenzt. Im Mais werden hauptsächlich junge zygotische Embryonen für die Herstellung der Regenerations-kompetenten Kalluskulturen benutzt. Der Arbeitsaufwand dafür ist hoch und die Prozedur schwierig und von den Gewächshausbedingungen abhängig. Im Rahmen dieser Arbeit wurden neue Gewebekultursysteme für Mais etabliert, welches junge Blattgewebe nutzt und somit unabhängig von Embryonen und Gewächshaus ist. Weiterhin wurden die aus Blättern gebildeten Kalluskulturen für die Generierung der genetisch veränderten Maispflanzen benutzt. Ebenso wurden verschiedene Selektionsmethoden für die Entwicklung eines Plastidentransformationssystems in Mais getestet. Jedoch konnten keine transplastomischen Maispflanzen erhalten werden. Sowohl die möglichen Ursachen als auch Vorschläge für weiterführende Versuche diesbezüglich werden im Rahmen dieser Arbeit diskutiert. Dennoch stellt diese Arbeit den ersten wesentlichen Schritt für die Entwicklung eines Plastidentransformationssystems in Mais vor. In einem zweiten Teil dieses Projekts wird die erfolgreiche Integration der Narzissen Phytoene Synthase in das Maisgenom durch das neu entwickelte nukleäre Transformationssystem gezeigt. Dadurch konnte eine signifikante Steigerung um 17% des Gesamtcarotinoid- und 21% des Beta-Carotengehalts in Maisblättern beobachtet werden. Schließlich wurden Fortschritte für die Entwicklung eines Transformationssystems für Peperomia (Piperaceae) durch die Etablierung eines Regenerationssystems aus Blättern gemacht. Außerdem wurden Faktoren, die die Plastidengröße und –zahl bestimmen, untersucht. Diese Ergebnisse geben Hinweise darauf, dass die Organellengröße und –zahl eher gewebespezifisch als in Abhängigkeit vom Plastidentyp reguliert wird. KW - Mais KW - genetische Manipulation KW - Regeneratin KW - Plastid KW - Maize KW - Genetic transformation KW - Regeneration KW - Plastid Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14572 ER -