NO donors. Part 16: investigations on structure-activity relationships of organic mononitrates reveal 2-nitrooxyethylammoniumnitrate as a high potent vasodilator

The vasoactive properties of 14 organic mononitrates were investigated in vitro using PGF(2alpha)-precontracted porcine pulmonary arteries. A surprisingly wide range of vasorelaxant potencies was observed (pD(2): 3.36-7.50). Activities showed to be highly sensitive to the molecular structure and the substituents at the molecular carrier of the nitrate group. A correlation between lipophilicity and vasorelaxant potency could not be recognized. 2-Nitrooxyethylammoniumnitrate (1) was found to be slightly superior to the high potency trinitrate GTN.     

Heterologous expression and in vitro assembly of the transmembrane cytochrome b6

Folding and assembly studies with alpha-helical membrane proteins are often hampered by the absence of high-level expression systems as well as by missing suitable in vitro refolding procedures. Experimental constraints and requirements for heterologous expression and in vitro assembly of cytochrome b6 have been examined and conditions for in vitro reconstitutions of the protein have been optimized. Cytochrome b6 can serve as an excellent model system for in vitro studies on the dynamic interplay of an apo-protein and heme cofactors during assembly of a transmembrane b-type cytochrome. In vitro assembled cytochrome b6 binds two hemes with different midpoint potentials and both ferri as well as ferro heme bind to the apo-cytochrome. However, the ferro cytochrome appears to be less stable than the ferri form.     

Activation of the PI3K pathway increases TLR-induced TNF-α and IL-6 but reduces IL-1β production in mast cells

Recognition of bacterial constituents by mast cells (MCs) is dependent on the presence of pattern recognition receptors, such as Toll-like receptors (TLRs). The final cellular response, however, depends on the influence of multiple environmental factors. In the current study we tested the hypothesis that the PI3K-activating ligands insulin-like growth factor-1 (IGF-1), insulin, antigen, and Steel Factor (SF) are able to modulate the TLR4-mediated production of proinflammatory cytokines in murine MCs. Costimulation with any of these ligands caused increased LPS-triggered secretion of IL-6 and TNF-α, but attenuated the production of IL-1β, though all three cytokines were produced in an NFκB-dependent manner. The pan-specific PI3K-inhibitor Wortmannin reverted the altered production of these cytokines. In agreement, MCs deficient for SHIP1, a negative regulator of the PI3K pathway, showed augmented secretion of IL-6/TNF-α and reduced production of IL-1β in response to LPS alone. The differential effects of IGF-1 on TLR4-mediated cytokine production were also observed in the context of TLR2 and IL-33 receptor-mediated MC activation. Importantly, these effects were seen in both bone marrow-derived and peritoneal MCs, suggesting general relevance for MCs. Using pharmacological and genetic tools, we could show that the p110δ isoform of PI3K is strongly implicated in SF-triggered suppression of LPS-induced IL-1β production. Costimulation with antigen was affected to a lesser extent. In conclusion, NFκB-dependent production of proinflammatory cytokines in MCs is differentially controlled by PI3K-activating ligand/receptor systems.     

Mixed messages from multiple information sources on invasive species: a case of too much of a good thing?

Aim The increasing number and availability of online databases of alien species beg a question of their comparability given most do not adopt standard criteria in the definition of species status or taxonomic treatment and vary in their comprehensiveness. In this study, we compare the consistency of two major European databases for the regions they have in common. We assess whether they use consistent terminology to classify species status, provide similar taxonomic classification and coverage, deliver comparable estimates of alien richness per country and identify comparable correlates of alien richness. Location Northern Europe. Methods Data on the total number of alien species as well as the number of established alien species were extracted from the online databases DAISIE and NOBANIS for 13 European countries and classified into comparable taxonomic groups. Analyses across countries examined trends in alien species richness, correlations among taxonomic groups and the explanatory power of population density, country area and per capita GDP on alien species richness. Results Alien species richness, intertaxon correlations and the significance of individual drivers of invasion were all strongly database dependent. Differences were more marked for total numbers of aliens than established aliens. Over all taxonomic groups, DAISIE had lower species richness and fewer significant intertaxon correlations but presented a greater number of significant explanatory models of alien species richness. Trends in species richness were not generally correlated between the two databases with human population density being a more important driver in DAISIE while country area had greater explanatory power in NOBANIS. Main conclusions Considerable caution should be applied when collating data from different databases because often their underlying structure and content may differ markedly. For Europe, the analysis indicates that having two contrasting databases is not an ideal basis for implementing invasive species policy and moves should be made soon to establish a central pan‐European database.     

The importin-alpha/nucleophosmin switch controls taspase1 protease function

Taspase1 is a threonine protease suspected to process (patho)biologically relevant nuclear and cytoplasmic substrates, such as the mixed lineage leukemia protein. However, neither the mechanisms regulating Taspase1's intracellular localization nor their functional consequences are known. Analysis of endogenous and ectopically expressed Taspase1 detected the protease predominantly in the nucleus accumulating at the nucleolus. Microinjection and ectopic expression studies identified an evolutionarily conserved bipartite nuclear import signal (NLS) (amino acids (197) KRNKRKLELA ERVDTDFMQLKKRR(220) ) interacting with importin-α. Notably, an NLS-mutated, import-deficient Taspase1 was biologically inactive. Although the NLS conferred nuclear transport already of the proenzyme, Taspase1's nucleolar localization required its autoproteolytic processing, triggering its interaction with the nucleolar shuttle protein nucleophosmin. In contrast, (auto)catalytically inactive Taspase1 mutants neither accumulated at the nucleolus nor bound nucleophosmin. Active nuclear import and interaction with nucleophosmin was found to be required for the formation of proteolytically active Taspase1 ensuring to efficiently process its nuclear targets. Intriguingly, coexpression of pathological nucleophosmin variants increased the amount of cytoplasmic Taspase1. Hence, Taspase1 appears to exploit the nuclear export activity of nucleophosmin to gain transient access to the cytoplasm required to also cleave its cytoplasmic substrates. Collectively, we here describe a hitherto unknown mechanism regulating the biological activity of this protease.     

Analysis of historic changes in regional ecosystem service provisioning using land use data

Land use change has a major impact on goods and services that our environment supplies for society. While detailed ecological or biophysical field studies are needed to quantify the exact amount of ecosystem service supply at local scales, such a monitoring might be unfeasible at the regional scale. Since field scale monitoring schemes for ecosystem services or ecosystem functioning are missing, proxy based indicators can help to assess the historic development of ecosystem services or ecosystem functioning at the regional scale. We show at the example of the historic development (1964–2004) in the district of Leipzig/Germany how land use/land cover data can be used to derive regional scale indicators for ecosystem functions. We focus thereby on two hypotheses: (1) the ecosystem functioning has degraded over time and (2) changes in land use configuration play an important role in this degradation. The study focuses on indicators for ecosystem functions related to (i) water purification by riparian buffer strips, (ii) pollination, (iii) food production and (iv) outdoor recreation. Each indicator builds on the analysis of land use configuration and land use composition information and is tested on sensitivity/robustness with respect to parameters which had to be estimated based on expert knowledge. We show that land use composition is an important aspect in our ecosystem service assessment. Although our study region is faced with a maximum land use change of 11% in the major land use classes between 1964 and 2004, we see a decrease of ecosystem function indicators up to 23%. The regional assessment shows an overall trend for degradation of ecosystem functioning from 1964 to 1984. This trend is reversed between 1984 and 1994 but the process slowed down until 2004 without reaching the level of 1964.