Biogeochemical transformations occurring in the anoxic zones of stratified sedimentary microbial communities can profoundly influence the isotopic and organic signatures preserved in the fossil record. Accordingly, we have determined carbon isotope discrimination that is associated with both heterotrophic and lithotrophic growth of pure cultures of sulfate-reducing bacteria (SRB). For heterotro...

The aim of this study was to investigate the possible existence and magnitude of stable carbon isotope discrimination by human 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). The catalytic portion of HMGR was expressed and purified. The reaction product mevalonate was lactonized and extracted from the reaction mixture by a solid-phase extraction protocol. Stable carbon isotope ratios of...

Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the...

Isotopic discrimination and turn-over are fundamental to the application of stable isotope ecology in animals. However, detailed information for specific tissues and species are widely lacking, notably for herbivorous species. We provide details on tissue-specific carbon and nitrogen discrimination and turn-over times from food to blood, feathers, claws, egg tissues and offspring down feathers ...

The appearance of agriculture in the Fertile Crescent propelled the development of Western civilization. Here we investigate the evolution of agronomic conditions in this region by reconstructing cereal kernel weight and using stable carbon and nitrogen isotope signatures of kernels and charcoal from a set of 11 Upper Mesopotamia archaeological sites, with chronologies spanning from the onset o...

A comparative study has been made of the photosynthetic physiological ecology and carbon isotope discrimination characteristics for modern-day bryophytes and closely related algal groups. Firstly, the extent of bryophyte distribution and diversification as compared with more advanced land plant groups is considered. Secondly, measurements of instantaneous carbon isotope discrimination (Delta), ...

the upper cretaceous carbonate sequence of ab-deraz formation is well exposed in the kopet- dagh basin. this formation comprises marly limestone and three chalky limestone units. chalky limestone of ab-deraz formation is mainly composed of calcareous dinoflagellate (pithonellid calcispher), cocolithofore and planktonic foraminifera. carbon and oxygen stable isotopes analysis of the third chalky...