Syntheses of Four Methyl-branched Secondary Acetates and a Methyl-branched Ketone as Possible Candidates for the Female Pheromone of the Screwworm Fly,Cochliomyia hominivorax

6-Acetoxy-19-methylnonacosane (1), 7-acetoxy-19-methylnonacosane (2), 8-acetoxy-19-methylnonacosane (3), 7-acetoxy-15-methylnonacosane (4), and 21-methyl-7-hentriacontanone (5) were synthesized as racemic and diastereomeric mixtures. These are new compounds isolated from an HPLC fraction of the female hexane extract which elicited mating responses in the male screwworm fly, Cochliomyia hominivorax.     

Hollandite as a Functional and Structural Model for the Biological Water Oxidizing Complex: Manganese-Calcium Oxide Minerals as a Possible Evolutionary Origin for the CaMn4 Cluster of the Biological Water Oxidizing Complex

Oxygen evolution was observed upon mixing either hollandite, which has been proposed as a structural model for the biological water oxidizing complex, or hausmannite with an aqueous solution of cerium (IV) ammonium nitrate. Oxygen evolution from water during irradiation with visible light (λ > 400 nm) was also observed upon adding either hollandite or hausmannite to an aqueous solution containing tris (2,2′-bipyridyl)ruthenium(II) chloride and chloro pentaammine cobalt(III) chloride in acetate buffer. These experiments showed that hollandite is a good catalyst for oxygen evolution in presence of cerium (IV) ammonium nitrate or tris (2,2′-bipyridyl)ruthenium (III). Thus, hollandite is not only a structural but also a functional model for the biological water oxidizing complex. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental file.     

Development and Use of an Aquatic Micro-Ecosystem as a Test System for Toxic Substances. Properties of an Aquatic Micro-Ecosystem IV

Experiments were performed using several modifications of a micro-ecosystem made up of three subsystems connected by a unidirectional flow of recirculating water. The three subsystems represent roughly the trophic levels of autotrophs (algae), herbivores (Daphnia magna), and decomposers (sandfilter with bacteria). The particle concentration was determined weekly, using a Coulter Counter, and the Daphnia population was counted. At regular intervals, the species composition of the algae was determined. The changes in the algal concentration and Daphnia population are described, and the different modifications are discussed. In several micro-ecosystems, the herbicide dichlobenil was introduced once or several times, and in one micro-ecosystem, the herbicide diuron was added. The response of the micro-ecosystems is discussed. For the periods without a toxic substance present, a normal operating range is suggested in relation to which the response of the systems to the introduced herbicide is discussed. Besides the separate analysis of the data, the algal concentrations and the Daphnia numbers were correlated to each other. This was done by regression analysis and according to a dynamic system approach. In both cases, the effect of herbicides was better discerned than in the separate analysis of the data. In the dynamic systems approach, a normalized ecosystem strain was defined as a parameter to measure effects of stress on the ecosystem level.