04 Fakultät Energie-, Verfahrens- und Biotechnik
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Item Open Access Item Open Access Frosttoleranz bei Pflanzen - Fliehen, vermeiden oder einfach durchhalten!(2005) Heyer, Arnd G.Nur etwa ein Drittel der Fläche des Planeten Erde ist dauerhaft frostfrei: in den tropischen Regenwaldgebieten des Amazonasbeckens, in Kongo, an der afrikanischen Westküste, auf dem Indomalayischen Archipel, in einem kleinen Teil Australiens und auf den pazifischen Inseln in Äquatornähe fällt die Temperatur nie unter etwa 15 Grad. Der Temperaturunterschied zwischen Tag und Nacht ist hier größer als der zwischen Sommer und Winter. Fast die Hälfte aller Pflanzenarten – 115.000 von 250.000 bekannten Blütenpflanzen – kommen nur hier vor. Daraus lässt sich bereits ablesen, dass der Umgang mit niedrigen Temperaturen eine Herausforderung für lebende Organismen ist, der sich nicht jeder stellen mag. Andererseits locken die kälteren Gegenden mit einem großen Flächen- und Mineralstoffangebot – einer Ressource, die für Pflanzen äußerst attraktiv ist.Item Open Access Neuere Ergebnisse der Photosynthese-Forschung(1971) Kull, UlrichDie komplexen Vorgänge, die wir zusammenfassend als Photosynthese bezeichnen, laufen in allen grünen Pflanzen und nur in diesen (einschließlich bestimmter Bakterien) ab. Diese Vorgänge liefern die Energie für den Lebensprozeß der Pflanzen und indirekt der heterotrophen Organismen, somit insbesondere auch von Tier und Mensch. Weiterhin stammt ein erheblicher Teil der Energiereserven des Menschen aus Photosyntheseprodukten (Kohle, Erdöl). Bei der Photosynthese wird mit Hilfe von Lichtenergie organische Substanz aus anorganischer aufgebaut. Dabei ist Kohlendioxid der C-Lieferant.Item Open Access Molekulare Grundlagen der Evolution(1975) Kull, UlrichDie Etablierung der Molekularbiologie in den letzten 20 Jahren führte zu der Erkenntnis, daß der Evolutionsvorgang eine molekulare Basis hat und mußte somit zwangsläufig die Frage aufwerfen, wie diese molekularen Grundlagen aussehen. Diese Ausführungen behandeln die Untersuchung der molekularen Mechanismen des Evolutionsprozesses, wobei natürlich die molekularen phylogenetischen Schemata zur Erkennung von Gesetzmäßigkeiten herangezogen werden müssen.Item Open Access Incorporation of 14C-photosynthate into major chemical fractions of leaves and bark of Ceratonia siliqua L. at different seasons(1993) Diehl, Susanne; Kull, Ulrich; Diamantoglou, StergosParts of branches of Ceratonia siliqua (L.) were exposed to 14CO2 for 3h during the growth period in April, after termination of growth (end of May), in the summer drought period (August) and in the cool winter (February). Twigs were harvested immediately after the end of the feeding period as well as after 48 and 144h. Simultaneously with the last harvest of exposed plant parts, controls from outside the exposure-chamber were also gathered. The total 14C-incorporation into leaves and bark as well as the labelling and contents of soluble sugars, starch, total lipids and other precipitable soluble compounds were determined. Total 14C-incorporation immediately after termination of 14CO2 application is a measure of the assimilation rate; it was high and nearly identical in April and May, but low (only about 5% of the April value) in summer ;and winter. The incorporation of 14C into soluble structural components was highest in April. Uptake of total 14C and labelling of soluble compounds during the 6-day period of the experiments show that metabolic rates were very low in summer but high during spring. The turnover of soluble compounds in February was remarkably high regarding the low CO2-fixation rate. The labelling of soluble sugars in leaves decreased in all experiments; the specific activity of starch remained rather stable. The incorporation of 14C into the lipid fraction was weak in all seasons and significant alterations took place only during the growing period. Variation in assimilation rates of Ceratonia at different seasons was comparable to that found for other mediterranean species using IRGA methods. There was no indication that lipids in Ceratonia are true storage compounds and participate in cyclic metabolic processes preventing stress effects. The weak turnover of lipids leads to the conclusion that maintenance costs for these compounds, as calculated by Merino et al. (1984). perhaps are too high, at least for Ceratonia. Our results do not suggest a specific adaptation of the metabolism of storage compounds to summer drought in Ceratonia.Item Open Access Field-effect sensors for virus detection : from Ebola to SARS-CoV-2 and plant viral enhancers(2020) Poghossian, Arshak; Jablonski, Melanie; Molinnus, Denise; Wege, Christina; Schöning, Michael J.Coronavirus disease 2019 (COVID-19) is a novel human infectious disease provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, no specific vaccines or drugs against COVID-19 are available. Therefore, early diagnosis and treatment are essential in order to slow the virus spread and to contain the disease outbreak. Hence, new diagnostic tests and devices for virus detection in clinical samples that are faster, more accurate and reliable, easier and cost-efficient than existing ones are needed. Due to the small sizes, fast response time, label-free operation without the need for expensive and time-consuming labeling steps, the possibility of real-time and multiplexed measurements, robustness and portability (point-of-care and on-site testing), biosensors based on semiconductor field-effect devices (FEDs) are one of the most attractive platforms for an electrical detection of charged biomolecules and bioparticles by their intrinsic charge. In this review, recent advances and key developments in the field of label-free detection of viruses (including plant viruses) with various types of FEDs are presented. In recent years, however, certain plant viruses have also attracted additional interest for biosensor layouts: Their repetitive protein subunits arranged at nanometric spacing can be employed for coupling functional molecules. If used as adapters on sensor chip surfaces, they allow an efficient immobilization of analyte-specific recognition and detector elements such as antibodies and enzymes at highest surface densities. The display on plant viral bionanoparticles may also lead to long-time stabilization of sensor molecules upon repeated uses and has the potential to increase sensor performance substantially, compared to conventional layouts. This has been demonstrated in different proof-of-concept biosensor devices. Therefore, richly available plant viral particles, non-pathogenic for animals or humans, might gain novel importance if applied in receptor layers of FEDs. These perspectives are explained and discussed with regard to future detection strategies for COVID-19 and related viral diseases.Item Open Access Item Open Access Rapid kinetin effects on lipid synthesis in isolated mesophyll protoplasts of Petunia(1980) Kull, Ulrich; Ultes, U.-Item Open Access Vorkommen von Sedoheptulose in Samen und vegetativen Teilen einiger Angiospermen(1968) Kull, UlrichSedoheptulose wild erstmals in freier Form in Samen einiger höherer Pflanzen (Vertretern der Gattung Saxifraga) nachgewiesen. In den Samen von 4 Arten werden die freien Zucker quantitativ bestimmt. Außerdem wird über weitere Vorkommen von Sedoheptulose in vegetativen Teilen verschiedener höherer Pflanzen berichtet.Item Open Access Physiological investigations of leaf mucilages. 2, The mucilage of Taxus baccata L. and of Thuja occidentalis L.(1985) Distelbarth, Heidrun; Kull, UlrichSeasonal variations of the content of leaf mucilages of Taxus baccata and Thuja occidentalis were determined. In Taxus the content is highest during the late winter and early spring and lowest in the summer. In Thuja it is highest in the winter, decreasing during spring and low in the summer months. Under the light microscope, Taxus mucilage was located in the vacuoles of mesophyll cells and that of Thuja in mucilage idioblasts. Temperature experiments show that storage of mucilage is not temperature dependent and is not reduced by prolonged darkness. Taxus mucilage consists of the sugars galactose, rhamnose, glucose, arabinose and xylose and contains a low percentage (<5%) of uronic acid. Furthemore, a peptidic component is found and shows annual variations from 6% to 15% of total mucilage. Seasonal variations of the sugar components are pronounced only during the spring in the period of intensive mucilage synthesis. Purified Taxus mucilage could not be separated into different components by gel chromatography. All fractions showed a similar composition of sugars and peptide. These findings, in addition to the IR spectra, lead to the conclusion that the mucilage is a proteoglycan and perhaps a mixture of polymers of similar molecular weights. Isolated and dried mucilage has a high water-binding capacity; at 96% relative humidity it equilibrates to 180%, and at 100% rh to 280-300% of its dry weight. From mucilage content and cell volume the mucilage concentration of the vacuoles can be estimated as being higher than 5-6%, which must give rise to a remarkable matric potential. It is suggested that the water-binding capacity of the mucilage plays an important role in stabilizing the water relations of the needles, thereby increasing frost resistance.