04 Fakultät Energie-, Verfahrens- und Biotechnik

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Publication Type: search.filters.UBSTyp.ZeitschriftenartikelAuthor: search.filters.author.Diamantoglou, Stergos

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    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, Stergos
    Parts 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.
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    Kohlenhydratgehalte und osmotische Verhältnisse bei Blättern und Rinden von Arbutus unedo L. und Arbutus andrachne L. im Jahresgang
    (1984) Diamantoglou, Stergos; Kull, Ulrich
    In den letzten Jahren wurden an den beiden Arbutus-Arten des Mittelmeergebiets mehrfach ökophysiologische Untersuchungen durchgeführt, insbesondere nachdem sich gezeigt hatte, daß sie sich beim mittäglichen Spaltenschluß unterschiedlich verhalten. Befunde zur Speicherungsphysiologie liegen von verschiedenen Ericaceen Mitteleuropas vor; daher schien es von Interesse, die mediterrane Gattung Arbutus damit zu vergleichen. Über den Lipidhaushalt der beiden Arbutus-Arten wurde bereits berichtet; dabei zeigte sich, daß im Gegensatz zu verschiedenen mitteleuropäischen Ericaccen und zu anderen mediterranen Sklerophyllen in Arbutus keine sehr starke Lipidakkumulation stattfindet. Wie bei anderen Sklerophyllen liegt das Minimum des Lipidgehaltes in der Zeit der sommerlichen Dürre. Wir berichten hier über die Jahresperiodik der Kohlenhydrate und des Energiehaushaltes der Reservestoffe in Blättern und Rinden der beiden Arbutus-Arten.
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    Das jahresperiodische Verhalten der Fettsäuren in Rinden und Blättern von Pinus halepensis Mill. und Schinus molle L.
    (1981) Diamantoglou, Stergos; Kull, Ulrich
    The fatty acid composition of the saponifiable lipids from barks and leaves of Pinus halepensis and of Schinus molle was investigated throughout the period of a year by gas liquid chromatography. Both species showed a great variety of different fatty acids of saponifiable lipids. In barks of Pinus, the contents of stearic, oleic and linoleic acids are higher during late winter and the growth period, whereas the percentage of behenic, lignocerinic, octadecatetraenoic, eicosatrienoic, and eicosatetraenoic acids was larger during the summer drought period and the autumn months. In the needles of Pinus, the contents of linolenic acid and of the short-chain acids (caprinic and laurinic) showed maxima during the winter and the growth period. In barks of Schinus we found a larger fraction of linolenic, erucic, and lignocerinic acids during the same period; in the leaves of this species linoleic, linolenic, behenic, and lignocerinic acids accumulated during the winter. There is no unequivocal influence of summer-drought on fatty acid pattern. In all species of linoleic and linolenic acids the highest percentage is shown during the humid winter and growth periods, which seems to reflect the metabolic activity of the investigated tissues.
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    Seasonal trends in energy content and storage substances in the mediterranean shrub Ephedra
    (1989) Diamantoglou, Stergos; Rhizopoulou, Sophia; Herbig, Astrid; Kull, Ulrich
    Green branches of a shrub of Ephedra distachya L., growing in Athens, Greece, were investigated. The crude fibre content rises during the late growth period, levels off during winter, then declines as new shoots emerge in spring. The content of soluble sugars and of starch is high during winter, but rather low during the dry season. The content of total lipids rises during winter, especially during the late growth period until June and declines during the drought period. During the winter months in the total saponifiable lipids the percentage of linoleic and linolenic acids is high; however, during the growth and the drought period the content of palmitic acid is rather high. The contents of total nitrogen and protein nitrogen decrease in late spring and remain low until the end of the summer drought. Thereafter, both values rise markedly. Stored energy is lowest at the end of the summer drought period. The ashfree calorific values vary little throughout the year (but the difference is significant) : the highest value is obtained in November (19782 J/g), the lowest in May (19298 J/g). From our data, the tissue.construction cost was estimated to be 1.41-1.47 g glucose/g dry weigth. Ephedra distachya is suited to the mediterranean climate, as seen by its ability to adjust to climatic changes during the year while undergoing periods of growth and quiescence. The accumulation of sugar during the winter months suggests that Ephedra is also capable of growing under cold-stress conditions.
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    Die Jahresperiodik der Fettspeicherung und ihre Beziehungen zum Kohlenhydrathaushalt bei immergrünen mediterranen Holzpflanzen
    (1982) Diamantoglou, Stergos; Kull, Ulrich
    The content of total lipids of barks and leaves from Quercus coccifera, Pinus halepensis and Schinus molle are -in accordance with our earlier findings concerning mediterranean shrub species- high during the winter and low during the summer months. The amount of lipids in leaves and barks of Quercus as well as in Ieaves of Schinus increases already towards the end of the summerdrought period. During winter, the fraction of linoleic and linolenic acids of the total sapenifiable lipids increases, most probably due to low lemperature. This is in accordance with the results of our previous investigations on sclerophylous shrubs, such as Ceratonia siliqua und Pistacia lentiscus. Summarizing the data from all species, we find an accumulation of sugars during the period of climatic stress in summer and an accumulation of lipids mainly during periods of relatively high metabolic activity and little growth intensity in winter. There is no accumulation of soluble sugars during winter in the mediterranean specics. The leaves of the sclerophyllous species show a rather high lipid content throughout the year; this could be advantageous for CO2-recycling during the summerdrought. Based on the calculation of energy values of storage products one can conclude that lipids in the skerophyllous species Ceratonia, Pistacia and Quercus contain the main portion or the total energy. Minimal values of stored energy are round during the summer-drought period.