5-methyl-3-butyl-octahydroindolizine,a novel type of pheromone attractive to Pharaoh's ants (Monomorium pharaonis (L.)

Zusammenfassung Aus Arbeiterinnen der AmeiseMonomorium pharaonis (L.) wurde 5-Methyl-3-butyl-octahydroindolizin isoliert. Dieses Pheromon übt eine starke Lockstoffwirkung auf die Arbeiterinnen dieser Ameisenart aus. Die Struktur wurde durch Spektral-analyse und Synthese aufgeklärt. Unseres Wissens ist dies das erste Pheromon aus Insekten mit dem Indolizingerüst.

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Acknowledgment. This work was supported by the Ministry of Health and Environmental Hygiene of the Netherlands. Pharaoh's ants were supplied by Dr.A. Buschinger, Bonn, and Mr.W. R. C. M. van der Loo, Rotterdam. The spectroscopical work was done by a team includingR. Deen, P. J. F. Nooijen andS. J. Spijk andJ. M. Timmner assisted in the synthesis.     

Geochemistry: does U-Pb date Earth's core formation?

Constraining the timing of the formation of Earth's core, which defines the birth of our planet, is essential for understanding the early evolution of Earth-like planets. Wood and Halliday and Halliday discuss the apparent discrepancy between the U-Pb (60-80 Myr) and Hf-W clocks (30 Myr) in determining the timescale of Earth's accretion and core formation. We find that the information the authors present is at times contradictory (for example, compare Fig. 1 in ref. 1 with Fig. 1 in ref. 2) and confusing and could suggest that the U-Pb clock constrains core formation better than the Hf-W system. Here we point out the limitations of the U-Pb system and show that the U-Pb age cannot be used to argue for protracted accretion and/or core formation (>50 Myr) because this clock only records the processes that occurred during the last 1% of Earth's accretion and core formation in the Wood and Halliday mechanism.     

Tectonic contraction across Los Angeles after removal of groundwater pumping effects

After the 1987 Whittier Narrows and 1994 Northridge earthquakes revealed that blind thrust faults represent a significant threat to metropolitan Los Angeles, a network of 250 continuously recording global positioning system (GPS) stations was deployed to monitor displacements associated with deep slip on both blind and surface faults. Here we augment this GPS data with interferometric synthetic aperture radar imagery to take into account the deformation associated with groundwater pumping and strike-slip faulting. After removing these non-tectonic signals, we are left with 4.4 mm yr-1 of uniaxial contraction across the Los Angeles basin, oriented N 36 degrees E (perpendicular to the major strike-slip faults in the area). This indicates that the contraction is primarily accommodated on thrust faults rather than on the northeast-trending strike-slip faults. We have found that widespread groundwater and oil pumping obscures and in some cases mimics the tectonic signals expected from the blind thrust faults. In the 40-km-long Santa Ana basin, groundwater withdrawal and re-injection produces 12 mm yr-1 of long-term subsidence, accompanied by an unprecedented seasonal oscillation of 55 mm in the vertical direction and 7 mm horizontally.     

Einfluss von Streptomycin und von Tetracyclinen auf die Entwicklung keimender Samen

Summary Euler (1947) andM. L. Stein (1953) had observed that germinating seeds of barley, rye, wheat and other grasses are colourless when exposed to solutions containing more than 0.2% of streptomycin or dihydrostreptomycin. These plants are not inhibited in growth. The chlorophyll already formed is not destroyed by streptomycin.The present authors describe the bleaching effect on germinating seeds of chlortetracycline and tetracycline. These antibiotics inhibit or reduce the formation of chlorophyll in germinating seeds but the authors could not obtain this inhibition without toxic effects (reduced growth). Contrary to streptomycin, the tetracyclines are not able to precipitate nucleic acids and nucleoproteins.