Universität Stuttgart
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Item Open Access Cytokinins in different cell compartments after treatment with [8-14C]-kinetin : [abstract](1985) Graf, Josef A.; Dietz, B.; Kull, Ulrich-Item Open Access Prosomes of higher plants share biochemical properties : [abstract](1988) Schliephacke, Martin; Kremp, Anette; Schmid, Hans-Peter; Kull, Ulrich-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 Konstruktion, Leichtbau und Ökonomie bei Pflanzen(1989) Kull, Ulrich; Herbig, AstridDie Festigkeitseigenschaften von Achsen aus Pflanzenarten unterschiedlicher Stellung werden mit Hilfe der BIO-Methode (nach F. Otto) beschrieben und zu Energiegrößen in Beziehung gesetzt. Damit lassen sich Aufwandswerte K (dirnensionslos) berechnen, die dann auf die Lebensdauer der Achsen bezogen werden. Konstruktiv gute Wirtschaftlichkeit zeigen Achsen vom Bautypus der Gräser, Blattstiele von Farnen und Achsen vom Hopfen (Liane). Der K-Wert ausdauernder Achsen liegt höher, K/Lebensdauer ist aber ähnlich wie bei einjährigen. Kurzlebige Blüten- und Fruchtstiele haben einen hohen Aufwand je Zeit. Die Größe K/Lebensdauer wird in Verbindung mit der Selektion gebracht. Vergleiche mit menschlichen Konstruktionen schließen sich an.Item Open Access Der Stickstoffhaushalt immergrüner mediterraner Hartlaubblätter(1988) Diamantoglou, Stergos; Kull, UlrichThe seasonal variations of major nitrogenous components (total N, protein N) in sclerophyllous leaves of four mediterranean species - Ceratonia siliqua, Olea europaea var. sylvestris, Pistacia lentiscus and Quercus coccifera - were investigated throughout the whole lifetime of the leaves. The leaf-longevity of the first two species mentioned is about two yars, that of the latter two species is somewhat longer than one year. As reference values the raw fibre content and the total chlorophyll content of the leaves were also measured. The raw fibre content increase during leaf-growth, there-after it remains constant. In the leaves having a lifetime of two years, in the spring of the second year an additional increase, although weak, is observed. The chlorophyll content rises during the leaf growth, then remains unchanged for some time, but begins to decrease early. In the leaves of Ceratonia and Olea the shrinkage is recognized already in the spring of the second year. During the period of senescence, the decrease of chlorophyll a is more distinct than that of chlorophyll b. The total N content in all cases decreases during leaf-growth and then remains constant. In Ceratonia leaves it is reasonably high considering that it is an evergreen species. Rather early the N-content begins to decrease; which is intensified during the last months of the lifetime the leaves. This is due to the well-known export of N-compounds from senescent tissues. In Ceratonia leaves the N-content increases during the first winter; obviously they serve as N-storage organs. The content of protein-N in all species shows essentially the same variations as that of total N. Results of tests carried out in the months of January and August revealed that the proline content in the leaves of all species is higher during the drought period than during the cold period. Using the different reference-values, the variations of N-content during leaf longevity of the four species are discussed in connection with reflections on maintenance costs.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.