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  • Crassulacean acid metabolism  (2)
  • Habitat selection  (1)
  • Liver transplantation, oxygen consumption  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Crassulacean acid metabolism in tropical dicotyledonous trees of the genusClusia (1987)
    Springer
    Trees 1 (1987), S. 238-247 
    Details
    ISSN: 1432-2285
    Schlagwort(e): Citric acid ; Clusia ; Crassulacean acid metabolism ; Malic acid ; Tropics ; Venezuela
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The performance of crassulacean acid metabolism (CAM) by dicotyledonous trees of the genusClusia sampled at three sites in the state of Falcon in northern Venezuela is characterized.Clusia leaves have a somewhat succulent appearance. Unlike leaves of many other CAM plants, which are uniformly built up of very large isodiametric cells, there are distinct layers of palisade and spongy mesophyll, with individual cells being smaller. There is no specialized water storage tissue. δ13C values indicate thatC. multiflora in the elfin-cloud forest on top of Cerro Santa Ana, at ∼800 m altitude, performs C3 photosynthesis (δ13 −27.1‰). However,C. rosea in the tall cloud forest on Cerro Santa Ana (∼600m altitude), andC. rosea andC. alata in the dry forest on Serrania San Luis (∼900 m altitude) perform CAM (δ13C −14.1 to −19.2‰). InC. alta andC. rosea there were large day-night changes in the levels of malic and citric acids ranging from 63 to 240 mmol 1−1 for malid acid and from 35 to 112 mmol 1−1 for citric acid. The sum of the changes in malate and citrate levels accounts for the changes of titratable protons measured. With a day-night change of titratable protons of 768 mmol 1−1 in one of the analyses,C. rosea showed the highest value yet encountered in a CAM plant. Oscillations of free sugars (fructose, glucose, sucrose) and of starch were also analysed in the CAM performingClusia species. Carbon skeletons of the precursors involved in nocturnal malate and citrate synthesis largely derive from free sugars and not from polyglucan. Unlike some other CAM plants, there is no clear and quantitative correlation between day-night changes of organic acid levels and cell sap osmolality.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01816822
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Use of cover and the need to breathe: the effects of hypoxia on vulnerability of dwarf gouramis to predatory snakeheads (1987)
    Springer
    Oecologia 73 (1987), S. 127-132 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Predator-prey relations ; Habitat selection ; Refuge ; Respiration ; Cost of breathing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The behavior of dwarf gouramis (Colisa lalia, Pisces, Belontiidae) and their vulnerability to predation by snakeheads (Channa micropeltes, Pisces, Channidae) were observed at four dissolved oxygen concentrations. When the oxygen level was near saturation (8 ppm) or only moderately reduced (3 ppm), the gouramis rarely breathed air and spent most of their time in a patch of artificial vegetation. At extremely low oxygen concentrations (1 and 0 ppm) the gouramis increased their air-breathing frequency and spent less time in cover. Gouramis were more likely to be captured by the snakeheads when out of the vegetation, and thus were caught more quickly at lower oxygen levels, even though their air-breathing frequency declined and use of cover increased in the presence of the predators. These results indicate that dissolved oxygen concentration, which varies considerably in many fish habitats, can affect use of cover and risk of predation in fishes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00376988
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  • 3
    Digitale Medien
    Digitale Medien
    The relationship of systemic hemodynamics and oxygen consumption to early allograft failure after liver transplantation (1993)
    Springer
    Transplant international 6 (1993), S. 73-76 
    Details
    ISSN: 1432-2277
    Schlagwort(e): Liver transplantation, oxygen consumption ; Failure of liver transplantation, oxygen consumption ; Oxygen consumption, liver transplantation failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The early postoperative hemodynamic data of 88 patients who underwent primary liver transplantation between July 1989 and October 1990 at the University Health Center of Pittsburgh were analyzed to establish the relationship of systemic hemodynamics and oxygen consumption to perioperative allograft function. The 15 patients whose allografts failed within the 1 st month following transplantation were designated as group 1, while 73 patients who retained adequate graft function constituted group 2. Although the cardiac index and oxygen delivery did not differ significantly between the groups, group 1 consistently demonstrated a lower mean arterial pressure, oxygen consumption, arteriovenous oxygen content difference, and arterial ketone body ratio. The etiology of reduced oxygen consumption in group 1 patients is speculative, but the data support the notion that oxygen consumption is a useful, predictive indicator for liver allograft function after transplantation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00336648
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  • 4
    Digitale Medien
    Digitale Medien
    Crassulacean acid metabolism (CAM) in leaves of Aloe arborescens mill (1979)
    Springer
    Planta 145 (1979), S. 357-363 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Aloe ; Crassulacean acid metabolism ; CO2 fixation ; Phosphoenolpyruvate-carboxylase ; Water tissue
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the succulent leaves of Aloe arborescens Mill diurnal oscillations of the malic acid content, being indicative of Crassulacean Acid Metabolism (CAM), were exhibited only by the green mesophyll. In contrast, the malic acid level of the central chloroplast-free water-storing tissue remained constant throughout the day-night cycle. Apart from malate, the green tissue contained high amounts of isocitrat which was lacking in the water tissue. There was no significant transfer from the green mesophyll to the water tissue of 14C fixed originally via dark 14CO2 fixation in the mesophyll. Both isolated mesophyll and water tissue were capable of dark CO2 fixation yielding mainly malate as the first stable product. Both tissues have phosphoenolpyruvate carboxylase. However, the enzymes derived from the both sources could be distinguished by their molecular weights and by their kinetic properties, suggesting different phosphoenolpyruvate carboxylase proteins. The conclusion drawn from the experiments is that in a. arborescens the CAM cycle proceeds exclusively in the green mesophyll and that the water tissue, though capable of malate synthesis via β-carboxylation of phosphoenolpyruvate, behaves as an independent metabolic system where CAM is lacking. This view is supported by the finding that the cell walls bordering the green mesophyll from the water tissue lack plasmodesmata, hence conveniant pathways of metabolite transport.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00388361
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