Interacting effects of fertilization, mowing and grazing on plant species diversity of 1500 grasslands in Germany differ between regions

The relationship of different types of grassland use with plant species richness and composition (functional groups of herbs, legumes, and grasses) has so far been studied at small regional scales or comprising only few components of land use. We comprehensively studied the relationship between abandonment, fertilization, mowing intensity, and grazing by different livestock types on plant diversity and composition of 1514 grassland sites in three regions in North-East, Central and South-West Germany. We further considered environmental site conditions including soil type and topographical situation. Fertilized grasslands showed clearly reduced plant species diversity (−15% plant species richness, −0.1 Shannon diversity on fertilized grasslands plots of 16 m2) and changed composition (−3% proportion of herb species), grazing had the second largest effects and mowing the smallest ones. Among the grazed sites, the ones grazed by sheep had higher than average species richness (+27%), and the cattle grazed ones lower (−42%). Further, these general results were strongly modulated by interactions between the different components of land use and by regional context: land-use effects differed largely in size and sometimes even in direction between regions. This highlights the importance of comparing different regions and to involve a large number of plots when studying relationships between land use and plant diversity. Overall, our results show that great caution is necessary when extrapolating results and management recommendations to other regions.

High plant species richness indicates management-related disturbances rather than the conservation status of forests

There is a wealth of smaller-scale studies on the effects of forest management on plant diversity. However, studies comparing plant species diversity in forests with different management types and intensity, extending over different regions and forest stages, and including detailed information on site conditions are missing. We studied vascular plants on 1500 20 m × 20 m forest plots in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). In all regions, our study plots comprised different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests, which resulted from clear cutting or shelterwood logging), various stand ages, site conditions, and levels of management-related disturbances. We analyzed how overall richness and richness of different plant functional groups (trees, shrubs, herbs, herbaceous species typically growing in forests and herbaceous light-demanding species) responded to the different management types. On average, plant species richness was 13% higher in age-class than in unmanaged forests, and did not differ between deciduous age-class and selection forests. In age-class forests of the Schwäbische Alb and Hainich-Dün, coniferous stands had higher species richness than deciduous stands. Among age-class forests, older stands with large quantities of standing biomass were slightly poorer in shrub and light-demanding herb species than younger stands. Among deciduous forests, the richness of herbaceous forest species was generally lower in unmanaged than in managed forests, and it was even 20% lower in unmanaged than in selection forests in Hainich-Dün. Overall, these findings show that disturbances by management generally increase plant species richness. This suggests that total plant species richness is not suited as an indicator for the conservation status of forests, but rather indicates disturbances.

Distinct carbon sources indicate strong differentiation between tropical forest and farmland bird communities

The conversion of forest into farmland has resulted in mosaic landscapes in many parts of the tropics. From a conservation perspective, it is important to know whether tropical farmlands can buffer species loss caused by deforestation and how different functional groups of birds respond to land-use intensification. To test the degree of differentiation between farmland and forest bird communities across feeding guilds, we analyzed stable C and N isotopes in blood and claws of 101 bird species comprising four feeding guilds along a tropical forest-farmland gradient in Kenya. We additionally assessed the importance of farmland insectivores for pest control in C4 crops by using allometric relationships, C stable isotope ratios and estimates of bird species abundance. Species composition differed strongly between forest and farmland bird communities. Across seasons, forest birds primarily relied on C3 carbon sources, whereas many farmland birds also assimilated C4 carbon. While C sources of frugivores and omnivores did not differ between forest and farmland communities, insectivores used more C4 carbon in the farmland than in the forest. Granivores assimilated more C4 carbon than all other guilds in the farmland. We estimated that insectivorous farmland birds consumed at least 1,000 kg pest invertebrates km−2 year−1. We conclude that tropical forest and farmland understory bird communities are strongly separated and that tropical farmlands cannot compensate forest loss for insectivorous forest understory birds. In tropical farmlands, insectivorous bird species provide a quantitatively important contribution to pest control.

Thiazolides, a Novel Class of Anti-Infective Drugs, Effective Against Viruses, Bacteria, Intracellular and Extracellular Protozoan Parasites and Proliferating Mammalian Cells

The thiazolide nitazoxanide (2-acetolyloxy-N-(5-nitro 2-thiazolyl) benzamide; NTZ) is composed of a nitrothiazole- ring and a salicylic acid moiety, which are linked together through an amide bond. NTZ exhibits a broad spectrum of activities against a wide range of helminths, protozoa, enteric bacteria, and viruses infecting animals and humans. Since the first synthesis of the drug, a number of derivatives of NTZ have been produced, which are collectively named thiazolides. These are modified versions of NTZ, which include the replacement of the nitro group with bromo-, chloro-, or other functional groups, and the differential positioning of methyl- and methoxy-groups on the salicylate ring. The presence of a nitro group seems to be the prerequisite for activities against anaerobic or microaerophilic parasites and bacteria. Intracellular parasites and viruses, however, are susceptible to non-nitro-thiazolides with equal or higher effectiveness. Moreover, nitro- and bromo-thiazolides are effective against proliferating mammalian cells. Biochemical and genetic approaches have allowed the identification of respective targets and the molecular basis of resistance formation. Collectively, these studies strongly suggest that NTZ and other thiazolides exhibit multiple mechanisms of action. In microaerophilic bacteria and parasites, the reduction of the nitro group into a toxic intermediate turns out to be the key factor. In proliferating mammalian cells, however, bromo- and nitro-thiazolides trigger apoptosis, which may also explain their activities against intracellular pathogens. The mode of action against helminths may be similar to mammalian cells but has still not been elucidated.

Designing forest biodiversity experiments: general considerations illustrated by a new large experiment in subtropical China

1. Biodiversity-ecosystem functioning (BEF) experiments address ecosystem-level consequences of species loss by comparing communities of high species richness with communities from which species have been gradually eliminated. BEF experiments originally started with microcosms in the laboratory and with grassland ecosystems. A new frontier in experimental BEF research is manipulating tree diversity in forest ecosystems, compelling researchers to think big and comprehensively. 2. We present and discuss some of the major issues to be considered in the design of BEF experiments with trees and illustrate these with a new forest biodiversity experiment established in subtropical China (Xingangshan, Jiangxi Province) in 2009/2010. Using a pool of 40 tree species, extinction scenarios were simulated with tree richness levels of 1, 2, 4, 8 and 16 species on a total of 566 plots of 25.8x25.8m each. 3. The goal of this experiment is to estimate effects of tree and shrub species richness on carbon storage and soil erosion; therefore, the experiment was established on sloped terrain. The following important design choices were made: (i) establishing many small rather than fewer larger plots, (ii) using high planting density and random mixing of species rather than lower planting density and patchwise mixing of species, (iii) establishing a map of the initial ecoscape' to characterize site heterogeneity before the onset of biodiversity effects and (iv) manipulating tree species richness not only in random but also in trait-oriented extinction scenarios. 4. Data management and analysis are particularly challenging in BEF experiments with their hierarchical designs nesting individuals within-species populations within plots within-species compositions. Statistical analysis best proceeds by partitioning these random terms into fixed-term contrasts, for example, species composition into contrasts for species richness and the presence of particular functional groups, which can then be tested against the remaining random variation among compositions. 5. We conclude that forest BEF experiments provide exciting and timely research options. They especially require careful thinking to allow multiple disciplines to measure and analyse data jointly and effectively. Achieving specific research goals and synergy with previous experiments involves trade-offs between different designs and requires manifold design decisions.

Directed Metalation Cascade To Access Highly Functionalized Thieno2,3-fbenzofuran and Exploration as Building Blocks for Organic Electronics

A tandem directed metalation has been successfully applied to the preparation of thieno2,3-fbenzofuran-4,8-dione, providing an efficient and facile approach to symmetrically and unsymmetrically functionalize the thieno2,3-fbenzofuran core at the 2,6 positions as well as to introduce the electron-withdrawing or -donating groups (EWG or EDG) at its 4,8 positions. The presence of various functional groups makes late-stage derivatization attainable.

The Cytotoxic Mode of Action of the Venom of Cupiennius salei (Ctenidae)

The venom of the ctenid spider Cupiennius salei (Fig.16.1) is rich in components which belong to different functional groups. Besides low molecular mass compounds, the venom contains several disulphide-rich peptides, also called mini-proteins, which act as neurotoxins on ion channels or as enhancers of neurotoxins. Likewise, a variety of small cytolytic peptides, which destroy membranes very efficiently, and enzymes are present in the venom. Neurotoxins with cytolytic activity, cytolytic a-helical small cationic peptides and enzymes most probably attacking connective tissue and phospholipid membranes cause the overall cytotoxic effect of this venom. Synergistic and enhancing interactions between components enable the spider to achieve a maximum of toxicity with a minimum of venom quantity.

The Value of Adding Optics to Ecosystem Models: A Case Study

Many ecosystem models have been developed to study the ocean's biogeochemical properties, but most of these models use simple formulations to describe light penetration and spectral quality. Here, an optical model is coupled with a previously published ecosystem model that explicitly represents two phytoplankton (picoplankton and diatoms) and two zooplankton functional groups, as well as multiple nutrients and detritus. Surface ocean color fields and subsurface light fields are calculated by coupling the ecosystem model with an optical model that relates biogeochemical standing stocks with inherent optical properties (absorption, scattering); this provides input to a commercially available radiative transfer model (Ecolight). We apply this bio-optical model to the equatorial Pacific upwelling region, and find the model to be capable of reproducing many measured optical properties and key biogeochemical processes in this region. Our model results suggest that non-algal particles largely contribute to the total scattering or attenuation (> 50% at 660 nm) but have a much smaller contribution to particulate absorption (< 20% at 440 nm), while picoplankton dominate the total phytoplankton absorption (> 95% at 440 nm). These results are consistent with the field observations. In order to achieve such good agreement between data and model results, however, key model parameters, for which no field data are available, have to be constrained. Sensitivity analysis of the model results to optical parameters reveals a significant role played by colored dissolved organic matter through its influence on the quantity and quality of the ambient light. Coupling explicit optics to an ecosystem model provides advantages in generating: (1) a more accurate subsurface light-field, which is important for light sensitive biogeochemical processes such as photosynthesis and photo-oxidation, (2) additional constraints on model parameters that help to reduce uncertainties in ecosystem model simulations, and (3) model output which is comparable to basic remotely-sensed properties. In addition, the coupling of biogeochemical models and optics paves the road for future assimilation of ocean color and in-situ measured optical properties into the models.

Biodiversity effects on nitrate concentrations in soil solution: a Bayesian model

Ecosystems are faced with high rates of species loss which has consequences for their functions and services. To assess the effects of plant species diversity on the nitrogen (N) cycle, we developed a model for monthly mean nitrate (NO3-N) concentrations in soil solution in 0-30 cm mineral soil depth using plant species and functional group richness and functional composition as drivers and assessing the effects of conversion of arable land to grassland, spatially heterogeneous soil properties, and climate. We used monthly mean NO3-N concentrations from 62 plots of a grassland plant diversity experiment from 2003 to 2006. Plant species richness (1-60) and functional group composition (1-4 functional groups: legumes, grasses, non-leguminous tall herbs, non-leguminous small herbs) were manipulated in a factorial design. Plant community composition, time since conversion from arable land to grassland, soil texture, and climate data (precipitation, soil moisture, air and soil temperature) were used to develop one general Bayesian multiple regression model for the 62 plots to allow an in-depth evaluation using the experimental design. The model simulated NO3-N concentrations with an overall Bayesian coefficient of determination of 0.48. The temporal course of NO3-N concentrations was simulated differently well for the individual plots with a maximum plot-specific Nash-Sutcliffe Efficiency of 0.57. The model shows that NO3-N concentrations decrease with species richness, but this relation reverses if more than approx. 25 % of legume species are included in the mixture. Presence of legumes increases and presence of grasses decreases NO3-N concentrations compared to mixtures containing only small and tall herbs. Altogether, our model shows that there is a strong influence of plant community composition on NO3-N concentrations.

Plant diversity effects on the water balance of an experimental grassland

In the literature, contrasting effects of plant species richness on the soil water balance are reported. Our objective was to assess the effects of plant species and functional richness and functional identity on soil water contents and water fluxes in the experimental grassland of the Jena Experiment. The Jena Experiment comprises 86 plots on which plant species richness (0, 1, 2, 4, 8, 16, and 60) and functional group composition (zero to four functional groups: legumes, grasses, tall herbs, and small herbs) were manipulated in a factorial design. We recorded meteorological data and soil water contents of the 0·0–0·3 and 0·3–0·7 m soil layers and calculated actual evapotranspiration (ETa), downward flux (DF), and capillary rise with a soil water balance model for the period 2003–2007. Missing water contents were estimated with a Bayesian hierarchical model. Species richness decreased water contents in subsoil during wet soil conditions. Presence of tall herbs increased soil water contents in topsoil during dry conditions and decreased soil water contents in subsoil during wet conditions. Presence of grasses generally decreased water contents in topsoil, particularly during dry phases; increased ETa and decreased DF from topsoil; and decreased ETa from subsoil. Presence of legumes, in contrast, decreased ETa and increased DF from topsoil and increased ETa from subsoil. Species richness probably resulted in complementary water use. Specific functional groups likely affected the water balance via specific root traits (e.g. shallow dense roots of grasses and deep taproots of tall herbs) or specific shading intensity caused by functional group effects on vegetation cover. Copyright © 2013 John Wiley & Sons, Ltd.

Biotic and Abiotic Properties Mediating Plant Diversity Effects on Soil Microbial Communities in an Experimental Grassland

Plant diversity drives changes in the soil microbial community which may result in alterations in ecosystem functions. However, the governing factors between the composition of soil microbial communities and plant diversity are not well understood. We investigated the impact of plant diversity (plant species richness and functional group richness) and plant functional group identity on soil microbial biomass and soil microbial community structure in experimental grassland ecosystems. Total microbial biomass and community structure were determined by phospholipid fatty acid (PLFA) analysis. The diversity gradient covered 1, 2, 4, 8, 16 and 60 plant species and 1, 2, 3 and 4 plant functional groups (grasses, legumes, small herbs and tall herbs). In May 2007, soil samples were taken from experimental plots and from nearby fields and meadows. Beside soil texture, plant species richness was the main driver of soil microbial biomass. Structural equation modeling revealed that the positive plant diversity effect was mainly mediated by higher leaf area index resulting in higher soil moisture in the top soil layer. The fungal-to-bacterial biomass ratio was positively affected by plant functional group richness and negatively by the presence of legumes. Bacteria were more closely related to abiotic differences caused by plant diversity, while fungi were more affected by plant-derived organic matter inputs. We found diverse plant communities promoted faster transition of soil microbial communities typical for arable land towards grassland communities. Although some mechanisms underlying the plant diversity effect on soil microorganisms could be identified, future studies have to determine plant traits shaping soil microbial community structure. We suspect differences in root traits among different plant communities, such as root turnover rates and chemical composition of root exudates, to structure soil microbial communities.

Functionalization of β-caryophyllene generates novel polypharmacology in the endocannabinoid system

The widespread dietary plant sesquiterpene hydrocarbon β-caryophyllene (1) is a CB2 cannabinoid receptor-specific agonist showing anti-inflammatory and analgesic effects in vivo. Structural insights into the pharmacophore of this hydrocarbon, which lacks functional groups other than double bonds, are missing. A structure-activity study provided evidence for the existence of a well-defined sesquiterpene hydrocarbon binding site in CB2 receptors, highlighting its exquisite sensitivity to modifications of the strained endocyclic double bond of 1. While most changes on this element were detrimental for activity, ring-opening cross metathesis of 1 with ethyl acrylate followed by amide functionalization generated a series of new monocyclic amides (11a, 11b, 11c) that not only retained the CB2 receptor functional agonism of 1 but also reversibly inhibited fatty acid amide hydrolase (FAAH), the major endocannabinoid degrading enzyme, without affecting monoacylglycerol lipase (MAGL) and α,β hydrolases 6 and 12. Intriguingly, further modification of this monocyclic scaffold generated the FAAH- and endocannabinoid substrate-specific cyclooxygenase-2 (COX-2) dual inhibitors 11e and 11f, which are probes with a novel pharmacological profile. Our study shows that by removing the conformational constraints induced by the medium-sized ring and by introducing functional groups in the sesquiterpene hydrocarbon 1, a new scaffold with pronounced polypharmacological features within the endocannabinoid system could be generated. The structural and functional repertoire of cannabimimetics and their yet poorly understood intrinsic promiscuity may be exploited to generate novel probes and ultimately more effective drugs.

Hydrogen-bonding complexes of functionalized BEDT-TTF derivatives with chloranilic acid

The two crystalline donor-acceptor complexes showing hydrogen-bondings between bis(ethylenedithio) tetrathiofulvalene (BEDT-TTF) derivatives containing pyridine and pyrazine groups and 2,5-dichloro-3,6-dihydroxyl-1,4-benzoquinone (chloranilic acid) were prepared. X-ray structure analyses revealed that functional groups play an important role in constructing the unique crystal structures.

Distamycin-NA: A DNA analog with an aromatic heterocyclic polyamide backbone. Part 2. Solid-phase synthesis of distamycin-NAs containing the nucleobase uracil: Unexpected solvent participation in the coupling step

10.1002/hlca.19980810512.abs The synthesis of the Fmoc-protected amino acid 2 is presented. First attempts of amide-bond formation to the homodimer 4 in solution showed only poor coupling yields indicative for the low reactivity of the amino and carboxy groups in the building blocks 1 and 2, respectively (Scheme 1). Best coupling yields were found using dicyclohexylcarbodiimide (DCC) without any additive. The oligomerization of building block 2 adopting the Fmoc ((9H-fluoren-9-ylmethoxy)carbonyl) solid-phase synthesis yielded a mixture of N-terminal-modified distamycin-NA derivatives. By combined HPLC and MALDI-TOF-MS analysis, the N-terminal functional groups could be identified as acetamide and N,N-dimethylformamidine functions, arising from coupling of the N-terminus of the growing chain with residual AcOH or DCC-activated solvent DMF. An improved preparation of building block 2 and coupling protocol led to the prevention of the N-terminal acetylation. However, ‘amidination’ could not be circumvented. A thus isolated tetramer of 2, containing a lysine unit at the C-terminus and a N,N-dimethylformamidine-modified N-terminus, not unexpectedly, showed no complementary base pairing to DNA and RNA, as determined by standard UV-melting-curve analysis.

Structure of the histone mRNA hairpin required for cell cycle regulation of histone gene expression.

Expression of replication-dependent histone genes requires a conserved hairpin RNA element in the 3' untranslated regions of poly(A)-less histone mRNAs. The 3' hairpin element is recognized by the hairpin-binding protein or stem-loop-binding protein (HBP/SLBP). This protein-RNA interaction is important for the endonucleolytic cleavage generating the mature mRNA 3' end. The 3' hairpin and presumably HBP/SLBP are also required for nucleocytoplasmic transport, translation, and stability of histone mRNAs. RNA 3' processing and mRNA stability are both regulated during the cell cycle. Here, we have determined the three-dimensional structure of a 24-mer RNA comprising a mammalian histone RNA hairpin using heteronuclear multidimensional NMR spectroscopy. The hairpin adopts a novel UUUC tetraloop conformation that is stabilized by base stacking involving the first and third loop uridines and a closing U-A base pair, and by hydrogen bonding between the first and third uridines in the tetraloop. The HBP interaction of hairpin RNA variants was analyzed in band shift experiments. Particularly important interactions for HBP recognition are mediated by the closing U-A base pair and the first and third loop uridines, whose Watson-Crick functional groups are exposed towards the major groove of the RNA hairpin. The results obtained provide novel structural insight into the interaction of the histone 3' hairpin with HBP, and thus the regulation of histone mRNA metabolism.