Experimente über das Regulationsvermögen der Blastula von Triton taeniatus und Bombinator pachypus

Ohne Zusammenfassung     

The identity of Vincetoxicum in Norway

Norwegian Vincetoxicum has previously been referred to V. hirundinaria in standard floras but partly to an aberrant form, called var.fuscatum or ssp. fuscatum . Our comparative morphological and allozymatic data unambiguously relate present day Norwegian Vincetoxicum populations to V. rossicum as circumscribed in standard European floras, i. e. with brown corollas, dark purple coronas, and twining stems up to 2 m in height. However, specific status of this taxon is questionable and varietal rank has been suggested, e. g. V. hirundinaria var. rossicum . Present Norwegian occurrences probably represent descendants from introductions by man prior to 1865 (first Norwegian record). The species has established itself as a permanent member of the Norwegian flora and although restricted to relatively small areas in Oslo (Oslo Co.) and Drammen (Buskerud Co.), it shows invasive tendencies at present.     

Nitrilotriacetate Stimulation of Anaerobic Fe(III) Respiration by Mobilization of Humic Materials in Soil

An enrichment culture capable of naphthalene mineralization reduced Fe(III) oxides without direct contact in anaerobic soil microcosms when the Fe(III) was placed in dialysis membranes or entrapped within alginate beads. Both techniques demonstrated that a component in soil, possibly humic materials, facilitated Fe(III) reduction when direct contact between cells and Fe(III) was not possible. The addition of the synthetic Fe(III) chelator, nitrilotriacetic acid (NTA), to soil enhanced Fe(III) reduction across the dialysis membrane and alginate beads, with the medium changing from clear to a dark brown color. An NTA-soil extract was more effective in Fe(III) reduction than the extracted soil itself. Characteristics of the NTA extract were consistent with that of humic substances. The results indicate that NTA improved Fe(III) reduction not by Fe(III) solubilization but by extraction of humic substances from soil into the aqueous medium. This is the first study in which stimulation of Fe(III) reduction through the addition of chemical chelators is shown to be due to the extraction of electron-shuttling compounds from the soil and not to solubilization of the Fe(III) and indicates that mobilization of humic materials could be an important component of anaerobic biostimulation.