Pierre Albrecht

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The organic matter found in sedimentary rocks must derive from many sources; not only from ancient primary producers but also from consumers and secondary producers. In all of these organisms, isotope effects can affect the abundance and distribution of 13C in metabolites. Here, by using an improved form of a previously described technique in which the(More)
Fig. 1. Lead-lead diagram for whole meteorite samples of Appley Bridge (e l , 2, A D). The data, with Cation Diablo troilite lead but without 1, form an isochron with slope corresponding with an age of (4.569 + 0.018) AE. The diagram shows also the isotopic compositions corrected back 4.57 AE according to the individual g values (v l, 2, ~c); the corrected(More)
The sediments that now comprise the Messel shale accumulated 47 +/- 2 million years ago in anaerobic waters at the bottom of a lake. Subsequent depths of burial have not exceeded 300 m, nor has the temperature of the shale exceeded 40 degrees C. Contents of organic carbon reach 25%, and preservation of molecular structures has been excellent. Sixteen(More)
and molecular beams P. Sutter, M. Minniti, P. Albrecht, D. Farı́as, R. Miranda, and E. Sutter Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA Departamento de Fı́sica de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain Instituto de Ciencia de Materiales “Nicolás Cabrera,”(More)
Treibs [1-4] first isolated porphyrins from sediments and postulated their origin from biological tetrapyrroles. Specifically, through the diagenetic sequence now known as the Treibs Scheme (Fig. 1), he proposed that petroporphyrins of the DPEP type (1) formed from chlorophyll a (3) and that etioporphyrin III (2) derived from the heme group (4) of animal(More)
We analyzed temperature-induced changes of variant surface antigen (vsAg) expression in Paramecium primaurelia, using immuno-techniques and mRNA determinations. Upon a 23°C to 33°C shift, the old vsAg, type 156G, remains on the cell surface for a time, when already mRNA for the new form, 156D, is expressed. A considerable amount of 156D-specific mRNA is(More)
coprostanol supply. Konstanz is the largest harbor city in the lake area and thousands of people either arrive at or depart from Konstanz each day during the summer. The direct disposal of feces by passenger ships was banned in 1976, but legislative measures were slow to develop; the input of human excreta from pleasure boats will only be prohibited by law(More)
Glycerol tetraethers with head-to-head isoprenoid 40-carbon chains that are typical of archaebacteria, in particular of methanogens, were identified in the polar lipids of sediments and petroleums. These structures are at least partially preserved in the subsurface beyond the stage of petroleum formation. Their identification provides further evidence that(More)