Inhibition of early steps of de novo fatty-acid biosynthesis by different xenobiotica

The importance of the early steps of de novo fatty-acid biosynthesis is discussed in terms of rate-limiting enzymic reactions with respect to their inhibition by xenobiotics. The inhibitory spectra of allicin as an inhibitor of the acetyl-CoA-synthase, two classes of graminicides (cyclohexane-1,3-diones and aryloxyphenoxypropionic acids) as inhibitors of acetyl-CoA-carboxylase, and the two antibiotics cerulenin and thiolactomycin, which affect the condensing step in fatty-acid biosynthesis, are compared.     

Maintenance of labour.

In 160 women large but variable amounts of intravenous oxytocin were needed to induce labour within a reasonable time interval to 5 cm cervical dilatation. Thereafter 7 mU of oxytocin/min would maintain progress. Since large maintenance doses may cause obstetric problems it is recommended that a maintenance regimen should be used once labour has progressed to this stage.     

Spreading of human fibroblasts in serum-free medium: Inhibition by dithiothreitol and the effect of cold insoluble globulin (plasma fibronectin)

We have tested the effect of dithiothreitol (DTT) treatment on the initial spreading of human fibroblasts in serum-free medium in tissue culture dishes. Cell spreading was inhibited following treatment of these cells with 10 mM DTT. Inhibition occurred when the cells were treated at 37°C but not at 4° and was reversible metabolically but not by the addition of sulfhydryl oxidizing reagents. The inhibition was overcome when DTT-treated human fibroblasts were plated on cold insoluble globulin (plasma fibronectin)—coated dishes. Under these conditions spreading appeared to be completely normal, including the formation of focal adhesions. Analysis of the fibronectin concentrations in the human fibroblasts following DTT treatment indicated that there was little decrease in the absolute level of activity as determined in a biological assay for BHK cell spreading on culture dishes. Analysis of the fibronectin distribution on the DTT-treated human fibroblasts by indirect immunofluorescence using a specific anti-CIG antiserum revealed that fibronectin was no longer deposited onto the culture dish surfaces. Even when the DTT-treated human fibroblasts spread in the presence of fetal calf serum, the cell fibronectin remained for the most part in a perinuclear location. These results indicate that DTT treatment of human fibroblasts prevents the normal translocation of fibronectin from a perinuclear location to the surface of the culture dish. This study further supports our hypothesis that the initial spreading in serum-free medium of fibroblasts from cell strains depends upon secretion of fibronectin onto the culture dish surface.     

Tomographic phase microscopy

We report a technique for quantitative three-dimensional (3D) mapping of refractive index in live cells and tissues using a phase-shifting laser interferometric microscope with variable illumination angle. We demonstrate tomographic imaging of cells and multicellular organisms, and time-dependent changes in cell structure. Our results will permit quantitative characterization of specimen-induced aberrations in high-resolution microscopy and have multiple applications in tissue light scattering.     

Iridoid biosynthesis in staphylinid rove beetles (Coleoptera: Staphylinidae, Philonthinae)

The biosynthesis of chrysomelidial and plagiodial was studied in the rove beetle subtribe Philonthina (Staphylinidae). Glandular homogenates were found to convert synthetic (2E,6E)-[trideuteromethyl-5,5-(2)H(5)]octa-2,6-diene-1,8-diol (10) into nor-chrysomelidial (14) and nor-plagiodial (13). The overall transformation requires; i) oxidation of the substrate at C(1) and C(8), ii) cyclization of the resulting dialdehyde to nor-plagiodial followed by iii) isomerization to give nor-chrysomelidial. The oxidase requires molecular oxygen as a cofactor and operates with removal of the pro-R hydrogen from C(1) and C(8) of synthetic (1R,8R,2E,6E)-[1,8-(2)H(2)]-2,6-dimethyl-octa-2,6-diene-1,8-diol (15), producing a dialdehyde along with H(2)O(2). Unlike enzymes from iridoid-producing leaf beetle larvae, the Philonthus enzyme is able to oxidize saturated substrates such as citronellol. Crude protein extracts prepared from Philonthus glands by ammonium sulfate precipitation, were found to produce hydrogen peroxide at a rate of 0.085+/-0.003 ng H(2)O(2) (ng protein)(-1) hr(-1) with nerol as an oxidase substrate. The cyclase operates with opposite stereochemistry to the enzyme(s) from Phaedon cochleariae and other herbivorous leaf beetles, specifically removing the C(5)-H(R) hydrogen atom from (4R,5S,2E,6E)-[4,5-(2)H(2)]-2-methyl-octa-2,6-diene-1,8-diol (17). These findings have enabled us to construct a detailed account of iridoid biosynthesis in rove beetles, which resembles the biosynthetic route in leaf beetle larvae, but exhibits distinct stereochemical differences.     

Indicators for biodiversity and ecosystem services: towards an improved framework for ecosystems assessment

Ecosystem assessment and monitoring requires the development and application of suitable indicators, i.e. they need to be (i) reliable and capable of simplifying complex relationships, (ii) quantifiable and transparent in order to enable an easy communication, and (iii) fit for the purpose of indication. These requirements are scarcely fulfilled in current ecosystem assessment and monitoring efforts to address the requirements of international biodiversity conventions. Here we present and test a set of seven criteria towards an improved framework for ecosystems indication with particular emphasis on the indication of biodiversity and ecosystem services: purpose of indication, indicator type according to the EEA’s Driver-Pressure-State-Impact-Response scheme, direct/indirect linkages to biodiversity and ecosystem services, spatial scale and scalability across scales, applicability of benchmarks/reference values, availability of data and protocols, and applicability of remote sensing. The criteria are tested using 24 indicators of ecosystem assessment and monitoring at the global, continental and regional scale. Based on the general trends revealed by our evaluation, we present recommendations to streamline and improve ecosystem indication with respect to international biodiversity conventions. The implementation of our recommendations does require concerted international effort, comparable, for instance, to the implementation of the Water Framework Directive in Europe.     

Lessons from practice: assessing early progress and success in river rehabilitation

This article comprises a literature analysis of 41 river rehabilitation projects to assess the short-term (5 years) ability of indicator groups to demonstrate progress towards river rehabilitation goals. Positive indications were compared to land-use, river size, rehabilitation intervention and time. A questionnaire was developed to investigate river manager’s interpretation of rehabilitation success and to assess their level of adherence to recommendations in the literature with regard to rehabilitation assessment on a conceptual level. A total of 54 responses were received from respondents based in Germany, The Netherlands and the United Kingdom. The results indicate that macroinvertebrate indicators, while widely used in assessing river rehabilitation efforts, exhibited a lower frequency of positive responses than most other indicator types in the short term. Conversely, terrestrial floodplain indicators exhibited the most frequent level of positive response for all ecological type indicators leading to recommendations for further investigations into their use for short-term monitoring. Assessment procedures recommended in literature are largely followed, illustrating the advances that have been made with regard to assessment planning. Indicator responses are influenced by scale factors, for example, land-use and river size, that are often not considered by rehabilitation managers. While an emphasis is placed on ecological, hydrological and morphological indicators in monitoring schemes, the socioeconomic perspective (emphasized in the literature as forming an integral part of the river system) is neglected.