217 000-year-old DNA sequences of green sulfur bacteria in Mediterranean sapropels and their implications for the reconstruction of the paleoenvironment

Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Society for Applied Microbiology and Blackwell for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 9 (2007): 238–249, doi:10.1111/j.1462-2920.2006.01134.x.Deep-sea sediments of the eastern Mediterranean harbor a series of dark, organic carbon-rich layers, so-called sapropels. Within these layers, the carotenoid isorenieratene was detected. Since it is specific for the obligately anaerobic phototrophic green sulfur bacteria, the presence of isorenieratene may suggest that extended water column anoxia occurred in the ancient Mediterranean Sea during periods of sapropel formation. Only three carotenoids (isorenieratene, β-isorenieratene and chlorobactene) are typical for green sulfur bacteria and thus do not permit to differentiate between the ~80 known phylotypes. In order to reconstruct the paleoecological conditions in more detail, we searched for fossil 16S rRNA gene sequences of green sulfur bacteria employing ancient DNA methodology. 540 bp-long fossil sequences could indeed be amplified from up to 217,000-year-old sapropels. In addition, such sequences were also recovered from carbon-lean intermediate sediment layers deposited during times of an entirely oxic water column. Unexpectedly, however, all the recovered 16S rRNA gene sequences grouped with freshwater or brackish, rather than truly marine, types of green sulfur bacteria. It is therefore feasible that the molecular remains of green sulfur bacteria originated from populations which thrived in adjacent freshwater or estuarine coastal environments rather than from an indigenous pelagic population.This work was funded by the Deutsche Forschungsgemeinschaft (grants Ov 20/3-2 and Ov 20/8-1 to 8-3)

Expression of cocaine-induced conditioned place preference in apomorphine susceptible and unsusceptible rats.

Contains fulltext : 49895.pdf (publisher's version ) (Closed access)Differences in cocaine self-administration can be attributed to differences in the rewarding value that cocaine has for the individual. An ongoing debate, however, exists whether a high rewarding or a low rewarding value leads to an increase in self-administration. To investigate which of these two alternatives is correct, we investigated the occurrence of cocaine-induced conditioned place preference in apomorphine susceptible and apomorphine unsusceptible rats. We have recently shown that under specific environmental conditions (challenged-not habituated to the environment-as measured by distance travelled) apomorphine susceptible rats consistently self-administer more cocaine than apomorphine unsusceptible rats do. As conditioned place preference allows the assessment of the rewarding value of cocaine, we investigated the expression of cocaine-induced conditioned place preference in apomorphine susceptible and apomorphine unsusceptible rats under the same conditions as the self-administration experiments in order to establish whether the rewarding value of cocaine is greater or smaller in challenged apomorphine susceptible rats than in challenged apomorphine unsusceptible rats. The data clearly showed that challenged apomorphine susceptible rats had a preference for the cocaine-paired compartment with lower doses of cocaine (10 mg/kg) than challenged apomorphine unsusceptible rats. Apomorphine unsusceptible rats expressed conditioned place preference only with the highest dose tested (20 mg/kg). On the basis of these data, we concluded that the rewarding value that cocaine has in challenged apomorphine susceptible rats is greater than that in challenged apomorphine unsusceptible rats. It is suggested that challenged apomorphine susceptible rats self-administer more of a lower dose of cocaine than challenged apomorphine unsusceptible rats do, because the rewarding value of cocaine is greater in challenged apomorphine susceptible rats than in challenged apomorphine unsusceptible rats

Effects of seabed protection on the Frisian Front and Central Oyster Grounds; A Cost Benefit Analysis

This report provides an overview of the important benefits and costs for six variant closures for the protection of the benthic ecosystem on the Frisian Front and the Central Oyster Grounds. The proposed closures lead to a range of ecological benefits and economic costs. The current study facilitates an informed discussion about an optimal allocation of the closures