The relation between cartilage biomarkers (C2C,C1,2C,CS846, and CPII) and the long-term outcome of rheumatoid arthritis patients within the CAMERA trial

Introduction  

The aim of this study was to investigate whether serum biomarker levels of C2C, C1,2C, CS846, and CPII can predict the long-term course of disease activity and radiographic progression early in the disease course of rheumatoid arthritis (RA).     

Mixed effects of landscape complexity and farming practice on weed seed removal

Agricultural intensification negatively affects farmland biodiversity, and thereby, ecosystem services such as predation of weed seeds. Landscape complexity (large and diverse areas of semi-natural habitats) and organic farming (without pesticides and mineral fertilizers) can counteract this negative trend, but little is known about their relative importance. We experimentally studied seed removal of four economically relevant weed species by excluding (i) vertebrates, (ii) vertebrates plus large invertebrates and (iii) neither vertebrates nor invertebrates (control) at the field edge and in the interior of 22 organically or conventionally managed winter wheat fields, located across a gradient of landscape complexity (41–94% arable land). Arable land (%) was used as a simple predictor of landscape complexity, as it is closely related to landscape parameters such as habitat type diversity. Seed predation and removal were mainly influenced by large invertebrates, seed species identity, with Cirsium arvense being more affected than Poa trivialis, Apera spica-venti and Galium aparine and landscape complexity in interaction with farming practice, as it increased in conventional fields, but decreased in organic fields as landscape complexity decreased. Seed predation and removal did not consistently correspond to seed predator densities, as small mammal abundances decreased in conventional fields, but increased in organic fields as landscape complexity decreased and carabid activity densities were higher in organic compared to conventional fields. Slug activity density showed same response to landscape complexity and farming practice like seed removal and appeared to additionally influence the movement of seeds. In conclusion, our assessment of interacting local and landscape effect adds to the current knowledge of seed predation and removal. Farming practice and landscape complexity affect seed predator species differentially, thereby resulting in complex pattern of seed predation and removal. The service of weed seed predation is provided by small mammals and invertebrates and the disservice of seed dispersal and movement is provided by slugs.     

The landscape context of cereal aphid-parasitoid interactions

Analyses at multiple spatial scales may show how important ecosystem services such as biological control are determined by processes acting on the landscape scale. We examined cereal aphid-parasitoid interactions in wheat fields in agricultural landscapes differing in structural complexity (32-100% arable land). Complex landscapes were associated with increased aphid mortality resulting from parasitism, but also with higher aphid colonization, thereby counterbalancing possible biological control by parasitoids and lastly resulting in similar aphid densities across landscapes. Thus, undisturbed perennial habitats appeared to enhance both pests and natural enemies. Analyses at multiple spatial scales (landscape sectors of 0.5-6 km diameter) showed that correlations between parasitism and percentage of arable land were significant at scales of 0.5-2 km, whereas aphid densities responded to percentage of arable land at scales of 1-6 km diameter. Hence, the higher trophic level populations appeared to be determined by smaller landscape sectors owing to dispersal limitation, showing the 'functional spatial scale' for species-specific landscape management.     

Local diversity of arable weeds increases with landscape complexity

Patterns of plant diversity are often related to local site conditions and to competitive interactions, but landscape context may also be important for local plant species richness. This is shown here by analysing the relationship between landscape complexity and local species richness of arable weeds in wheat fields. The fields were located in 18 landscapes characterised by a gradient in landscape complexity from structurally complex to structurally simple (39–94% arable land). We quantified local site conditions, field management intensity and landscape characteristics, and used principle component analyses to ordinate the environmental variables. The percentage of arable land was negatively correlated with perimeter–area ratio, habitat-type diversity and topographical heterogeneity, but landscape characteristics did not correlate with local site conditions and field management intensity. The number of plant species was mainly related to landscape characteristics and to a lesser extent to field management intensity (nitrogen fertilisation), whereas local soil characteristics did not contribute to the explanation of arable weed richness. In a geographic scale analysis using circular landscape sectors ranging from 1 km up to 5 km diameter, the predictive power of landscape complexity for local plant species richness was strongest at 2 km indicating a scale-dependent relationship between landscape context and plant species richness. Our results support the hypothesis that local plant species richness in arable fields is greatly influenced by processes operating at the landscape scale. Seed rain from ruderal source habitats and disturbed edges may be the most important underlying process.     

Phenology of neotropical pepper plants (Piperaceae) and their association with their main dispersers, two short-tailed fruit bats, Carollia perspicillata and C. castanea (Phyllostomidae)

To relate differences in phenological strategies of a group of closely related plants to biotic (pollinators, dispersers) and abiotic (water, light) factors, we studied leafing, flowering, and fruiting phenology of 12 species of Piper (Piperaceae) in a neotropical lowland forest in Panama for 28 months. We asked how Piper may partition time and vertebrate frugivores to minimize possible competition for dispersal agents. Based on habitat preferences and physiological characteristics we discriminate between forest Piper species (eight species) and gap Piper species (four species). Forest Piper species flowered synchronously mostly at the end of the dry season. Gap Piper species had broader or multiple flowering peaks distributed throughout the year with a trend towards the wet season. Both groups of Piper species showed continuous fruit production. Fruiting peaks of forest Piper species were short and staggered. Gap Piper species had extended fruiting seasons with multiple or broad peaks. Both groups of Piper species also differed in their time of ripening and disperser spectrum. Forest Piper species ripened in late afternoon and had a narrow spectrum consisting mainly of two species of frugivorous bats: Carollia perspicillata and C. castanea (Phyllostomidae). Fruits of gap Piper species, in contrast, ripened early in the morning and were eaten by a broader range of diurnal and nocturnal visitors, including bats, birds, and ants. We conclude that the differences in flowering phenology of forest and gap Piper species are primarily caused by abiotic factors, particularly the availability of water and light, whereas differences in fruiting patterns are mostly influenced by biotic factors. The staggered fruiting pattern of forest Piper species may reflect competition for a limited spectrum of dispersers. The long and overlapping fruiting periods of gap Piper species are associated with a larger spectrum of dispersers and may be a strategy to overcome the difficulty of seed dispersal into spatially unpredictable germination sites with suitable light conditions.     

Aphid suppression by natural enemies in mulched cereals

Large populations of natural enemies are the basis for natural pest control. Effects of mulch on predator–prey interactions in arable fields are poorly known, despite its potential to enhance ground‐dwelling predators and thereby reduce pest infestations. We studied the densities of predators and parasitoids, and their impact on cereal aphids in the presence and absence of mulch. Released populations of the bird cherry aphid, Rhopalosiphum padi (L.) (Homoptera: Aphididae), and two naturally occurring aphid species, were monitored under experimentally reduced densities of: (i) ground‐dwelling predators, (ii) flying predators and parasitoids, and (iii) with straw mulch. The three treatments were applied in a 2 × 2 × 2 factorial design in a field of spring wheat (Triticum aestivum L.). The exclusion of ground‐dwelling predators increased aphid populations by 55% in June and 40% in July, respectively. Mulched plots had 25% lower aphid densities in June. This was presumably due to enhanced densities of spiders (Araneida) in mulched plots. The exclusion of flying predators and parasitoids led to 94% higher aphid populations in late July (109 vs. 56 individuals per 100 shoots), irrespective of mulch or ground predator manipulation. This was attributed to the larvae of gall midges Aphidoletes cf. aphidimyza (Rondani) (Diptera: Cecidomyiidae) and hoverflies (Diptera: Syrphidae). The results indicate that a scarcity of predators and a bare soil surface renders crops more susceptible to arthropod pests. Farming schemes should aim at enhancing both ground‐dwelling and flying predators for elevated levels of natural pest control.     

Effects of landscape context on herbivory and parasitism at different spatial scales

Local community structure and interactions have been shown to depend partly on landscape context. In this paper we tested the hypothesis that the spatial scale experienced by an organism depends on its trophic level. We analyzed plant-herbivore and herbivore-parasitoid interactions in 15 agricultural landscapes differing in structural complexity using the rape pollen beetle ( Meligethes aeneus ), an important pest on oilseed rape ( Brassica napus ), and its parasitoids. In the very center of each landscape a patch of potted rape plants was placed in a grassy field margin strip for standardized measurement. Percent non-crop area of landscapes was negatively related to plant damage caused by herbivory and positively to the herbivores' larval mortality resulting from parasitism. In a geographic scale analysis, we quantified the structure of the 15 landscapes for eight circular sectors ranging from 0.5 to 6 km diameter. Correlations between parasitism and non-crop areas as well as between herbivory and non-crop area were strongest at a scale of 1.5 km, thereby not supporting the view that higher trophic levels experience the world at a larger spatial scale. However, the predictive power of non-crop area changed only slightly for herbivory, but greatly with respect to parasitism as scales from 0.5 to 1.5 km and from 1.5 to 6 km diameter increased. Furthermore, the effect of non-crop area tended to be stronger in parasitism than herbivory suggesting a greater effect of changes in landscape context on parasitoids. This is in support of the general idea that higher trophic levels should be more susceptible to disturbance.     

Flagellate algae (Chrysophyceae, Dinophyceae, Cryptophyceae) in 48 high mountain lakes of the Northern and Southern slope of the Eastern Alps: biodiversity, taxa distribution and their driving variables

Survey samplings on late summer phytoplankton communities were carried out on 48 high mountain lakes located on the Austrian and Italian slopes of the Eastern Alps. The lakes of North Tyrol (A) and South Tyrol (I) were sampled in 2000 as part of the EU project EMERGE (EVK1-CT-1999- 00032). The lakes of Trentino (I) were investigated in other research projects during 1996 and 1997 (Adamello mountain range) and 2000 (catchment of the River Avisio), respectively. The objectives of this paper are: (1) to study taxonomy and biodiversity of Chrysophyceae, Dinophyceae and Cryptophyceae in high altitude lakes of the Eastern Alps; (2) to identify functional flagellate groups characterising lakes with similar habitat properties, (3) to identify the environmental variables driving abundance and distribution of the three selected algal groups, thus contributing to the selection of sensitive bioindicator taxa. The lakes investigated show rather wide morphological, chemical and trophic state gradients. Flagellate algae account for a median relative abundance (R.A.) of 68%. Chrysophyceae are the most important group in terms of biodiversity and R.A. Special flagellate associations could be related to lake features, like catchment geology, mineralization level and nutrient concentrations. However, the distribution of flagellate algae did not allow a complete geographical separation of the lakes studied in the different districts. Multivariate canonical analyses indicate that the distribution of Chrysophyceae is mainly driven by NO₃-N concentration and thermal conditions, while Dinophyceae are driven by a combination of alkalinity, altitude, thermal condition and, less importantly, nutrient concentration. Physical properties of the lakes, such as thermal condition and lake depth, represent the principal driving variables for Cryptophyceae. The responses to the different environmental variables suggest that the three flagellate groups analysed might be used as indicators for environmental changes in high mountain lakes of the Eastern Alps.     

Upregulation of acetylcholine synthesis by bone morphogenetic protein 9 in a murine septal cell line.

Previous studies showed that bone morphogenetic protein 9 (BMP-9) induces the expression of choline acetyltransferase and the vesicular acetylcholine (ACh) transporter, and upregulates ACh synthesis in cultured primary neurons from embryonic mouse septum [I. López-Coviella, B. Berse, R. Krauss, R.S. Thies, J.K. Blusztajn, Induction and maintenance of the neuronal cholinergic phenotype in the central nervous system by BMP-9. Science 289 (2000) 313-316]. In the present studies we investigated the effects of BMP-9 on ACh synthesis in the cholinergic mouse SN56T17 septal cell line. BMP-9 increased ACh synthesis in these cells up to 2.5-fold in a time- and dose-dependent, saturable manner. The maximal effect of BMP-9 was observed after a 3-day treatment and the median effective concentration of BMP-9 was 0.5 ng/ml. These data show that SN56T17 cells are a useful model for studies of the effects of BMPs on the cholinergic phenotype.     

Light and electron microscopical postembedding lectin histochemistry for WGA-binding sites in the renal cortex of the mouse embedded in polyhydroxy aromatic resins LR-White and LR-Gold

This work describes a technique which permits study of the postembedding lectin histochemistry for WGA-binding sites at the light and electron microscopical level on the same resin embedded tissue without removing or etching of the resin. Unfixed kidney pieces or kidney pieces fixed in 4% formaldehyde were embedded in the hydrophilic polyhydroxy aromatic resins LR-Gold and LR-White, following dehydration in up to 70% ethanol, 90% ethanol or 100% ethanol. LR-Gold was cryopolymerised at -25 degrees C using the light sensitive initiator benzil, whereas LR-White was heat-cured at +50 degrees C. The localisation of WGA-binding sites at the light microscopical level was investigated using FITC-labelled WGA. The ultrastructural localisation of WGA-binding sites was performed using 15 nm gold-labelled WGA. The best fluorescence staining results were obtained on fixed or unfixed tissue dehydrated in up to 70% ethanol and embedded in LR-Gold. At the ultrastructural level, the best staining results for WGA-binding sites were seen on tissue sections, dehydrated in up to 90% ethanol prior to embedding in LR-Gold.