Vegetation development and floristical diversity of newly created sown and unsown field margin strips on ex arable land during the first 3 successional years

Early succesion of newly created sown/unsown margin strips on ex arableland, managed by two cuttings per year with/without removal of cuttings was characterised by the replacement of annuals in favour of perennials, a steadily increase in the importance of monocots and a decrease in non N-fixing dicots. Mowing with removal of cuttings delayed this succession pattern. Sorenson's qualitative similarity index (based solely on species occurrence) revealed that species composition of the sown communities (in terms of species occurrence) became increasingly similar to the unsown plots. Furthermore convergence in vegetation composition between sown and unsown plots occurred also in terms of species importance as assessed by Sorenson's quantitative index (based on the combination of species occurrence and importance). Similarity in species importance (but not of species occurrence) was significantly enhanced by cutting with removal of cuttings. During the first 3 successional years, species diversity of sown and unsown communities converged in time, irrespective of mowing regime or location. The decrease in species diversity, number of sown wildflower species and wildflower density of sown communities was more pronounced under a mowing regime without removal of cuttings. The annual addition of mown roadside herbage significantly enhanced species richness but not the importance of dicots.     

Production of tailor-made fructans in sugar beet by expression of onion fructosyltransferase genes

The consumption of fructans as a low caloric food ingredient or dietary fibre is rapidly increasing due to health benefits. Presently, the most important fructan source is chicory, but these fructans have a simple linear structure and are prone to degradation. Additional sources of high-quality tailor-made fructans would provide novel opportunities for their use as food ingredients. Sugar beet is a highly productive crop that does not normally synthesize fructans. We have introduced specific onion fructosyltransferases into sugar beet. This resulted in an efficient conversion of sucrose into complex, onion-type fructans, without the loss of storage carbohydrate content.     

Project models to improve the ambiance during meal times in Dutch nursing homes: incentives and barriers for implementation

In many Dutch nursing homes, meals are not served in a cozy setting. This study makes an inventory of project models used in nursing homes to improve the ambiance during mealtimes and identifies the beneficial factors (incentives) and barriers of the meal ambiance models. Three different meal ambiance project models were found: restaurant, cooking on the nursing ward and bulkmeals. Each of the three models was experienced as a success by the nursing home inhabitants, the nursing home management and the staff. They pointed out that the cooperation and motivation of staff, sufficient space and management support were the most important beneficial factors of the project models. The most important barriers were absence of cooperation and motivation of the staff, insufficient finances and insufficient personnel.     

Reproductive biology of the epiphytic bromeliad Werauhia gladioliflora in a premontane tropical forest

The floral phenology, fruit and seed production, and self-compatibility of Werauhia gladioliflora, an epiphytic bromeliad with a wide distribution, were studied in a premontane forest in the Monteverde area in Costa Rica. The species presents the pollination syndrome of chiropterophily, and it is visited by the small bats Hylonycteris underwoodi and Glossophaga commissarisi (Glossophaginae). The population flowering period extended from October to early December (end of rainy season) and seed dispersal occurred from February to April (dry season). Most plants opened a single flower per night, either every day or at one-day intervals during the flowering period. In natural conditions, the average fruit set amounted to almost half of the potential output, but individual fecundity (number of seeds) remained high. Seed number per fruit and germination capacity after artificial selfing and out-crossing treatments did not differ from natural pollination conditions. Werauhia gladioliflora exhibited high levels of autonomous self-pollination and self-compatibility at the individual and population level, characters associated with the epiphytic habitat. These reproductive traits are also associated with early colonizer species, yet life history traits, such as seed dispersal, seedling establishment success, and growth, are likely to have a major role in determining the presence of this species in the successional vegetation patches scattered over the studied premontane area.     

How do climate warming and plant species richness affect water use in experimental grasslands?

Climate warming and plant species richness loss have been the subject of numerous experiments, but studies on their combined impact are lacking. Here we studied how both warming and species richness loss affect water use in grasslands, while identifying interactions between these global changes. Experimental ecosystems containing one, three or nine grassland species from three functional groups were grown in 12 sunlit, climate-controlled chambers (2.25 m² ground area) in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration (ET) was higher. After an initial ET increase in response to warming, stomatal regulation and lower above-ground productivity resulted in ET values comparable with those recorded in the unheated communities. As a result of the decreased biomass production, water use efficiency (WUE) was reduced by warming. Higher complementarity and the improved competitive success of water-efficient species in mixtures led to an increased WUE in multi-species communities as compared to monocultures, regardless of the induced warming. However, since the WUE of individual species was affected in different ways by higher temperatures, compositional changes in mixtures seem likely under climatic change due to shifts in competitiveness. In conclusion, while increased complementarity and selection of water-efficient species ensured more efficient water use in mixtures than monocultures, global warming will likely decrease this WUE, and this may be most pronounced in species-rich communities.     

EFHC1, a protein mutated in juvenile myoclonic epilepsy, associates with the mitotic spindle through its N-terminus

A novel gene, EFHC1, mutated in juvenile myoclonic epilepsy (JME) encodes a protein with three DM10 domains of unknown function and one putative EF-hand motif. To study the properties of EFHC1, we expressed EGFP-tagged protein in various cell lines. In interphase cells, the fusion protein was present in the cytoplasm and in the nucleus with specific accumulation at the centrosome. During mitosis EGFP-EFHC1 colocalized with the mitotic spindle, especially at spindle poles and with the midbody during cytokinesis. Using a specific antibody, we demonstrated the same distribution of the endogenous protein. Deletion analyses revealed that the N-terminal region of EFHC1 is crucial for the association with the mitotic spindle and the midbody. Our results suggest that EFHC1 could play an important role during cell division.     

Human-induced hybridization among congeneric endemic plants on Tenerife, Canary Islands

Endemic genera on oceanic islands often evolved striking morphological and ecological differences among species, with weak postzygotic reproductive isolation. Human activities can lead to increased connectivity and can thereby promote secondary contact and hybridization between previously isolated species. We studied this phenomenon in three species of the genus Pericallis (Asteraceae) on Tenerife, Canary Islands. A total of 53 populations was sampled, including morphologically uniform as well as mixed populations containing morphologically diverse individuals. All plants were analyzed both genetically using AFLP markers and morphometrically. As expected, morphological analysis clearly separated the plants from the uniform populations in three clusters, with distinguishing characters corresponding to those used in species identification. The three species were also grouped into distinct genetic clusters in a structure analysis, although no private alleles were observed. Adding the mixed population data to the analyses provided evidence for extensive hybridization among species, predominantly between P. cruenta and P. echinata, and between P. cruenta and P. tussilaginis, and morphological and genetic signals were congruent. The mixed populations were geographically located in between the uniform populations and were found in road verges significantly more often than the uniform populations. The observed distribution strongly suggests that hybridization between originally isolated species is recent, promoted by secondary contact due to human disturbance and the construction of roads.     

Immunosuppression induced by immature dendritic cells is mediated by TGF-beta/IL-10 double-positive CD4+ regulatory T cells.

Dendritic cells (DC) have important functions in T cell immunity and T cell tolerance. Previously, it was believed that T cell unresponsiveness induced by immature DC (iDC) is caused by the absence of inflammatory signals in steady-state in vivo conditions and by the low expression levels of costimulatory molecules on iDC. However, a growing body of evidence now indicates that iDC can also actively maintain peripheral T cell tolerance by the induction and/or stimulation of regulatory T cell populations. In this study, we investigated the in vitro T cell stimulatory capacity of iDC and mature DC (mDC) and found that both DC types induced a significant increase in the number of transforming growth factor (TGF)-beta and interleukin (IL)-10 double-positive CD4(+) T cells within 1 week of autologous DC/T cell co-cultures. In iDC/T cell cultures, where antigen-specific T cell priming was significantly reduced as compared to mDC/T cell cultures, we demonstrated that the tolerogenic effect of iDC was mediated by soluble TGF-beta and IL-10 secreted by CD4(+)CD25(-)FOXP3(-) T cells. In addition, the suppressive capacity of CD4(+) T cells conditioned by iDC was transferable to already primed antigen-specific CD8(+) T cell cultures. In contrast, addition of CD4(+) T cells conditioned by mDC to primed antigen-specific CD8(+) T cells resulted in enhanced CD8(+) T cell responses, notwithstanding the presence of TGF-beta(+)/IL-10(+) T cells in the transferred fraction. In summary, we hypothesize that DC have an active role in inducing immunosuppressive cytokine-secreting regulatory T cells. We show that iDC-conditioned CD4(+) T cells are globally immunosuppressive, while mDC induce globally immunostimulatory CD4(+) T cells. Furthermore, TGF-beta(+)/IL-10(+) T cells are expanded by DC independent of their maturation status, but their suppressive function is dependent on immaturity of DC.     

Line tensions, correlation lengths, and critical exponents in lipid membranes near critical points

Membranes containing a wide variety of ternary mixtures of high chain-melting temperature lipids, low chain-melting temperature lipids, and cholesterol undergo lateral phase separation into coexisting liquid phases at a miscibility transition. When membranes are prepared from a ternary lipid mixture at a critical composition, they pass through a miscibility critical point at the transition temperature. Since the critical temperature is typically on the order of room temperature, membranes provide an unusual opportunity in which to perform a quantitative study of biophysical systems that exhibit critical phenomena in the two-dimensional Ising universality class. As a critical point is approached from either high or low temperature, the scale of fluctuations in lipid composition, set by the correlation length, diverges. In addition, as a critical point is approached from low temperature, the line tension between coexisting phases decreases to zero. Here we quantitatively evaluate the temperature dependence of line tension between liquid domains and of fluctuation correlation lengths in lipid membranes to extract a critical exponent, ν. We obtain ν = 1.2 ± 0.2, consistent with the Ising model prediction ν = 1. We also evaluate the probability distributions of pixel intensities in fluorescence images of membranes. From the temperature dependence of these distributions above the critical temperature, we extract an independent critical exponent of β = 0.124 ± 0.03, which is consistent with the Ising prediction of β = 1/8.