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The twist-necked turtle (Platemys platycephala, Schneider 1792) is the only member of the genus Platemys. Despite a pan-Amazonian distribution in South America, ecology and population status of this small, forest-dwelling species are unknown in many countries within its range. Currently it is not listed in the IUCN Red List of Threatened Species, and there are almost no published data on reproduction, feeding, or habitat preferences in the wild. In this article, observations on habitat selection, short-term movements and feeding in the Nouragues Field Reserve, French Guyana, are reported for the first time. Study specimens used the same areas in the late rainy season of 2009 and 2010, moving total distances of 503-686 m over a period of approximately 3 wk within calculated areas of activity ranging in size between 0.73 and 1.59 ha. The main habitats used were palm swamps, temporary flooded forest, and primary nonflooded forest. The analysis of 4 stomach and 2 fecal samples showed that different classes of insects, worms and crustaceans as well as amphibian eggs were consumed as food items. © 2013 Chelonian Research Foundation. Source


Krimmel B.,University of Vienna | Swoboda F.,University of Vienna | Solar S.,University of Vienna | Reznicek G.,Althanstrasse
Radiation Physics and Chemistry | Year: 2010

The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH3 by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed. © 2010 Elsevier Ltd. Source


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Chemists from the University of Vienna around Annette Rompel have analysed the structure of the enzyme in the leaves of Coreopsis. Credit: Annette Rompel What is it that walnut leaves, mushrooms and Coreopsis have in common? An enzyme that is also responsible for the browning reaction in bananas or apples is present in all of them in large amounts. For the first time, chemists from the University of Vienna around Annette Rompel have analyzed the structure of the enzyme in the leaves of Coreopsis. Who doesn't know the brown colour of a sliced apple or overripe fruit? Annette Rompel, Head of the Department of Biophysical Chemistry at the University of Vienna, knows this phenomenon very well. Since more than 20 years, she has studied the tyrosinase, an enzyme that does not only exist in plants but also makes the human skin become brown. The "browning" is caused by a number of complex polyphenols. These are secondary plant metabolites that occur, e.g. as health-promoting colouring and flavouring components. Tyrosinase, in turn, is a metal-containing enzyme that catalyses the hydroxylation and oxidation of phenols. "And this is the reason for the discolouration", explains the chemist. In addition to tyrosinase, a second enzyme called catechol oxidase is capable of oxidising diphenols such as catechol. "Thus, both enzymes are responsible for the browning reaction", says Rompel. The first author Christian Molitor stresses: "The actual physiological role of the enzymes in various cells as well as their natural substrates are still largely unknown." The chemists have addressed this question. Having successfully characterised the enzymes in mushrooms and walnut leaves, the researchers now focus on another plant: Coreopsis—a popular garden plant whose flowers resemble those of sunflowers with their radiant yellow blossoms also found in the University's greenhouse in Althanstrasse. "This is mainly due to the excellent work of the gardeners Thomas Joch and Andreas Schröfl", says Rompel who praises the employees "with the green thumb". Where does the yellow colour come from? "We have chosen Coreopsis for our research, because the "browning enzyme" is found in the petals in high concentrations", says the chemist. The enzyme—in this case a catechol oxidase—is responsible for the conversion of certain flower pigments. "Since the petal dyes are called aurones, the enzyme received the name aurone synthase", explains the chemist. A new classification must be defined Her team comprising Christian Molitor, Stephan Mauracher and Cornelia Kaintz managed to characterise this enzyme for the first time: In the paper recently published in PNAS, the researchers presented the first crystal structure of aurone synthase in both a latent and an active form. "In a third step, we had an inactive form (through sulfonation) isolated and crystallised", says Molitor, adding: "With regard to the crystal structures of the latent, active and inactive form we achieved results that provide further insight into the complex mechanism of activation." With their work, the researchers from the University of Vienna also describe a new mechanism for the catalytic cycle of plant polyphenol oxidases, i.e. the "browning process" in plants. "Our results show that the general classification of tyrosinase and catechol oxidase must be reconsidered", says first author Molitor. The research results could lead to applications in various disciplines, among others in biotechnological, pharmaceutical or agricultural processes. "Based on our results, you could—by controlling the enzymes —, for example, increase the content of bioactive substances in fruit and vegetables", explains Rompel and smiles: "Fruit and vegetables would then become even healthier." Explore further: No need to get browned off: Edible films keep fruit fresh More information: Christian Molitor et al. Aurone synthase is a catechol oxidase with hydroxylase activity and provides insights into the mechanism of plant polyphenol oxidases, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1523575113


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Who doesn't know the brown color of a sliced apple or overripe fruit? Annette Rompel, Head of the Department of Biophysical Chemistry at the University of Vienna, knows this phenomenon very well. Since more than 20 years, she has studied the tyrosinase, an enzyme that does not only exist in plants but also makes the human skin become brown. The "browning" is caused by a number of complex polyphenols. These are secondary plant metabolites that occur, e.g. as health-promoting coloring and flavoring components. Tyrosinase, in turn, is a metal-containing enzyme that catalyses the hydroxylation and oxidation of phenols. "And this is the reason for the discolouration", explains the chemist. In addition to tyrosinase, a second enzyme called catechol oxidase is capable of oxidising diphenols such as catechol. "Thus, both enzymes are responsible for the browning reaction", said Rompel. The first author Christian Molitor stresses: "The actual physiological role of the enzymes in various cells as well as their natural substrates are still largely unknown." The chemists have addressed this question. Having successfully characterized the enzymes in mushrooms and walnut leaves, the researchers now focus on another plant: Coreopsis -- a popular garden plant whose flowers resemble those of sunflowers with their radiant yellow blossoms also found in the University's greenhouse in Althanstrasse. "This is mainly due to the excellent work of the gardeners Thomas Joch and Andreas Schröfl", said Rompel who praises the employees "with the green thumb". Where does the yellow color come from? "We have chosen Coreopsis for our research, because the "browning enzyme" is found in the petals in high concentrations", said the chemist. The enzyme -- in this case a catechol oxidase -- is responsible for the conversion of certain flower pigments. "Since the petal dyes are called aurones, the enzyme received the name aurone synthase", explains the chemist. A new classification must be defined Her team comprising Christian Molitor, Stephan Mauracher and Cornelia Kaintz managed to characterize this enzyme for the first time: In the paper recently published in PNAS, the researchers presented the first crystal structure of aurone synthase in both a latent and an active form. "In a third step, we had an inactive form (through sulfonation) isolated and crystallised", said Molitor, adding: "With regard to the crystal structures of the latent, active and inactive form we achieved results that provide further insight into the complex mechanism of activation." With their work, the researchers from the University of Vienna also describe a new mechanism for the catalytic cycle of plant polyphenol oxidases, i.e. the "browning process" in plants. "Our results show that the general classification of tyrosinase and catechol oxidase must be reconsidered", said first author Molitor. The research results could lead to applications in various disciplines, among others in biotechnological, pharmaceutical or agricultural processes. "Based on our results, you could -- by controlling the enzymes --, for example, increase the content of bioactive substances in fruit and vegetables", explains Rompel and smiles: "Fruit and vegetables would then become even healthier."


The diversity, abundance and habitat of breeding raptors in the Austrian March floodplain forests, located in the border area between Austria, Slovakia and the Czech Republic, were studied in 2008. The study area (19.7 km?) had not been explored by ornithologists until the 1990s due to the considerable flood dynamics and the subsequent limited accessibility. The present field study was performed between January and July 2008 between Hohenau and Drösing (Lower Austria), consisting of two reference areas of comparable size but with different cultivation techniques, i.e. the high forest cultivation in the North (960 ha) and the middle forest cultivation in the South (1010 ha). Additionally, the field study was conducted to explore the influence of the vegetation structure around the nesting site (microhabitat, r=15 m, 706.5 m 2) and the landscape characteristics (macrohabitat, r=250 m, 19.6 ha) on the habitat choices of birds of prey. To get a representative sample for comparison, the same data were collected at 50 randomly selected sites. Aeries were mapped along transects between 50 m intervals, and 167 were found in total. 57 out of 167 aeries were occupied by birds of prey. In total, nine breeding raptor species were recorded. The most abundant species was the Common Buzzard (Buteo buteo), occupying 34 aeries, followed by the Marsh Harrier (Circus aeroginosus) with five or six pairs. The Red Kite (Milvus milvus) population, with a quantity of three pairs was remarkable on a national scale. The Black Kite (Milvus migrans) (three pairs), the Honey Buzzard (Pernis apivorus) (three pairs), the Goshawk (Accipiter gentilis) (three pairs), the Kestrel (Falco tinnunculus) (two pairs) and the Hobby (Falco subbuteo) (two pairs) also bred in the study area. Since 2002 the White-tailed Eagle (Haliaeetus albkiUa) has bred successfully in the floodplains. The Sparrowhawk (Accipiter nisus), the Saker Falcon (Falco cherrug) and the Imperial Eagle (Aquila heliaca) were not found as breeders in the study area, but were known to breed nearby. The results indicated a population growth of the Common Buzzard, whereas the density of other predatory birds has been steady for the last 15 years. The density is high compared to other places in central Europe, including the Danube floodplains in Austria. Besides, the density seems to be independent from the type of cultivation. The data concerning the habitat structure were analyzed in a Geographic Information System (GIS) and indicate the March flood-plain forests as very attractive for raptors. The investigation area offers a varied and structured landscape with abundant waterbodies and meadows. Predatory birds prefer old growth trees, particularly oaks (Quercus sp.) and poplars (Populus sp.) for nesting. These types of trees are numerous in middle forest cultivation. Additionally, a higher number of older aeries can be found there compared to high forest cultivations. Birds of prey prefer a distinctive forest structure with plenty of deadwood, far away from paths or protected by dense shrub and undergrowth. Therefore, the conservation of mature forests, the reduction of human disturbance and the reactivation of the flood dynamics could have a positive effect on the raptor population in the long term. © IfV, MPG 2010. Source

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