Über den Zusammenhang von Glykolsäure und lichtabhängiger Phosphorylierung

Zusammenfassung Glykolsäure fördert im Licht die Aufnahme von³²P und die Markierung der organisch-löslichen Fraktion inAnkistrodesmus braunii. Der relative Anteil der organisch-löslichen Fraktion an der Gesamteinlagerung wird durch steigenden Phosphatgehalt der Zelle erhöht. Die Ergebnisse werden dahingehend diskutiert, daß Glykolsäure oder eine aus ihr resultierende Verbindung durch das bei der Photosynthesephosphorylierung angelieferte ATP phosphoryliert wird.Mit 2 TextabbildungenMeinem hochverehrten Lehrer, Herrn Prof. Dr.C. Hoffmann, Kiel, in Verehrung und Dankbarkeit zum 60. Geburtstag gewidmet.     

Simulated VLF-fields as a risk factor of thrombosis

VLF (Very Low Frequencies)-fields are damped electromagnetic waves of atmospheric origin (sferics). Sferics were artificially produced within a steel-built chamber; blood was drawn and platelet adhesiveness, platelet cyclic AMP and coagulation factors were measured in human volunteers placed within the chamber. Following frequency of the impulses of 10 Hz and a field strength of 400 mV/m increased platelet adhesiveness and decreased platelet cyclic AMP. Medication of the anti-platelet drugs were not effective at all, but the pretreatment of dipyridamole 75 mg combined with acetylsalicylic acid 100 mg blocked the sferics induced increment in platelet adhesiveness. Psychologically labile volunteers exhibited more marked effects of sferics upon platelet adhesiveness. Simulation of stressors upon platelets showed the same effect. The increase in platelet adhesiveness induced by all kind of stressors is not a risk factor of thrombosis in itself. Only if the vessel walls are damaged, e.g. by atherosclerotic plaques, or if the blood flow is reduced, e.g. by heart failure, then the increased platelet adhesiveness will cause thrombosis.Supported by Deutsche Forschungsgemeinschaft and Landesamt für Forschung NRW.     

Isolation of Carnation Italian Ringspot Virus from a Creek in a Forested Area South West of Bonn

During a survey of plant viruses in small ponds and creeks in a forested area near Bad Münstereifel about 30 km south-west of Bonn several viruses were isolated. One of these was identified as carnation Italian ringspot virus which previously has been isolated only twice from carnations originating from Italy and USA and which infected carnations only with difficulty. The role of this virus in the forest ecosystem is so far unknown.     

Effects of invasive alien kahili ginger (Hedychium gardnerianum) on native plant species regeneration in a Hawaiian rainforest

Questions: Does the invasive alien Hedychium gardnerianum (1) replace native understory species, (2) suppress natural regeneration of native plant species, (3) increase the invasiveness of other non‐native plants and (4) are native forests are able to recover after removal of H. gardnerianum. Location: A mature rainforest in Hawai'i Volcanoes National Park on the island of Hawai'i (about 1200 m a.s.l.; precipitation approximately 2770 mm yr^?1). Study sites included natural plots without effects of alien plants, ginger plots with a H. gardnerianum‐dominated herb layer and cleared plots treated with herbicide to remove alien plants. Methods: Counting mature trees, saplings and seedlings of native and alien plant species. Using non‐parametric H‐tests to compare impact of H. gardnerianum on the structure of different sites. Results: Results confirmed the hypothesis that H. gardnerianum has negative effects on natural forest dynamics. Lower numbers of native tree seedlings and saplings were found on ginger‐dominated plots. Furthermore, H. gardnerianum did not show negative effects on the invasive alien tree species Psidium cattleianum. Conclusions: This study reveals that where dominance of H. gardnerianum persists, regeneration of the forest by native species will be inhibited. Furthermore, these areas might experience invasion by P. cattleianum, resulting in displacement of native canopy species in the future, leading to a change in forest structure and loss of other species dependent on natural rainforest, such as endemic birds. However, if H. gardnerianum is removed the native Hawaiian forest is likely to regenerate and regain its natural structure.     

Morphologie und Anatomie des Enteropneusten Saccoglossus pygmaeus Hinr. & Jac.

Ohne ZusammenfassungMit 28 Abbildungen im Text.     

Abiotic factors controlling the establishment and abundance of the invasive golden mussel Limnoperna fortunei

Limnoperna fortunei (Bivalvia, Mytilidae), a freshwater bivalve native to Southern Asia, has been an invasive species in South America since 1991. It spread upstream in the La Plata basin reaching the Paraguay River in the vicinity of the Pantanal wetland, Brazil, around 1998. The role of abiotic factors in controlling establishment and abundance of this species is not well known, making projections of its risk of further spread difficult. This study evaluates the importance of abiotic factors to L. fortunei populations established in rivers of the Pantanal, focusing on larval and juvenile densities and taking advantage of a wide range of seasonal variability in water temperature, flow, dissolved oxygen, and suspended material. Temperature, river stage (influencing several water characteristics) and water velocity are the main variables related to the larval and juvenile densities. In the Pantanal, environmental variables vary over a broader range compared with other South American locations, subjecting L. fortunei to oxygen depletion, low calcium, low pH, and high water velocity and suspended solids, associated with low chlorophyll a concentrations. The combined effect of several of these conditions may explain the relatively low densities in some Pantanal sites. However, they probably will not prevent the persistence of populations in the Pantanal and the eventual establishment of viable populations in upriver systems connected to the Pantanal. These results are pertinent not only to this species but also to other aquatic invasive invertebrates whose expansion may be limited by thermal extremes, episodic oxygen depletion, and waters that are too dilute or acidic for optimal biocalcification.