Recombinant protein production by in vivo polymer inclusion display

A novel approach to produce purified recombinant proteins was established. The target protein is produced as polyhydroxyalkanoate (PHA) synthase fusion protein, which mediates intracellular formation of PHA inclusions displaying the target protein. After isolation of the PHA inclusions, the pure target protein was released by simple enterokinase digestion.     

Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem

The major aims of this study were, firstly, to analyse the grazing-induced steppe degradation process and, secondly, to identify an efficient and sustainable grazing management system for the widely degraded Inner Mongolian typical steppe ecosystem. From 2005?C2008 a grazing experiment was conducted to compare two grazing management systems, the Mixed System (MS) and the Traditional System (TS), along a gradient of seven grazing intensities, i.e. ungrazed (GI0), very-light (GI1), light (GI2), light-moderate (GI3), moderate (GI4), heavy (GI5), and very-heavy (GI6). Each grazing intensity treatment was considered a production unit comprising two adjacent plots, one for hay-making (single-cut system) and one for grazing. Hay-making and grazing alternated annually in the MS, while in the TS the same plots were used either for hay-making or for grazing. Effects of management system, grazing intensity, and year on end-of-season standing biomass (ESSB), aboveground net primary production (ANPP), relative difference in ANPP between 2005 and 2008 (ANPP_Diff), relative growth rate (RGR), and sward characteristics (litter accumulation, soil coverage) were analysed. Litter accumulation of production units was affected by grazing intensity (P?<?0.001) and decreased from GI0 to GI6 by 83%. Correspondingly, soil coverage decreased (P?<?0.001) from GI0 to GI6 by 43%, indicating an increased vulnerability to soil erosion. We found varying compensatory growth responses to grazing intensity among years, probably because of temporal variability in precipitation. The ability of plants to partially compensate for grazing damage was enhanced in years of greater seasonal precipitation. The ANPP of production units was negatively affected by grazing intensity and decreased from GI0 to GI6 by 37, 30, and 55% in 2006 (P?<?0.01), 2007 (P?<?0.05), and 2008 (P?<?0.001), respectively. The effect of management system × grazing intensity interaction on ANPP (P?<?0.05) and ANPP_Diff (P?<?0.05) suggested greater grazing resilience of the MS as compared to the TS at GI3 to GI6.     

Effects of fertilization and irrigation on productivity, plant nutrient contents and soil nutrients in southern Mongolia

The study attempts to evaluate the effect of fertilization and irrigation on steppe productivity in dry southern Mongolian desert-steppes. We conducted an irrigation- and NPK fertilization experiment, irrigating at levels of +100 mm and fertilizers at amounts equivalent to 20 gN (m² year)^?1 in a factorial design. We tested the effects on soil nutrients and biomass production. Nutrients in plant tissue were analysed for Stipa krylovii and S. gobica, and for mixed sub-samples of total above- and belowground biomass. Available P and K and total K increased in the soil after fertilization while irrigation reduced total N. Biomass yield almost tripled and inflorescence numbers increased by factors of 4?C8 due to fertilization while irrigation alone had very restricted effects and only increased biomass of Agropyron cristatum. Nutrient content of biomass was elevated on fertilized plots. Results indicate that steppe productivity is severely restricted by nutrient availability even under ambient precipitation levels, raising the question whether nutrient withdrawal caused by current land use practices has detrimental effects on pasture productivity. The anticipated beneficial effect of increasing water availability however could not be confirmed. Whether there is an improvement in productivity due to increasing rainfall, as predicted by some climate change models, will depend on the distribution and intensity of rain events.     

Spatial and temporal variation of soil moisture in dependence of multiple environmental parameters in semi-arid grasslands

Grazing of grasslands changes soil physical and chemical properties as well as vegetation characteristics, such as vegetation cover, species composition and biomass production. In consequence, nutrient allocation and water storage in the top soil are affected. Land use and management changes alter these processes. Knowledge on the impacts of grazing management on nutrient and water fluxes is necessary because of the global importance of grasslands for carbon sequestration. Soil water in semi-arid areas is a limiting factor for matter fluxes and the intrinsic interaction between soil, vegetation and atmosphere. It is therefore desirable to understand the effects of grazing management and stocking rate on the spatial and temporal distribution of soil moisture. In the present study, we address the question how spatio-temporal soil moisture distribution on grazed and ungrazed grassland sites is affected by soil and vegetation properties. The study took place in the Xilin river catchment in Inner Mongolia (PR China). It is a semi-arid steppe environment, which is characterized by still moderate grazing compared to other regions in central Inner Mongolia. However, stocking rates have locally increased and resulted in a degradation of soils and vegetation also in the upper Xilin River basin. We used a multivariate geostatistical approach to reveal spatial dependencies between soil moisture distribution and soil or vegetation parameters. Overall, 7 soil and vegetation parameters (bulk density, sand, silt and clay content, mean weight diameter, mean carbon content of the soil, vegetation cover) and 57 soil moisture data sets were recorded on 100 gridded points on four sites subject to different grazing intensities. Increasing stocking rates accelerated the influence of soil and vegetation parameters on soil moisture. However, the correlation was rather weak, except for a site with high stocking rate where higher correlations were found. Low nugget ratios indicate spatial dependency between soil or plant parameters and soil moisture on a long-term ungrazed site. However, the effect was not found for a second ungrazed site that had been excluded from grazing for a shorter period. Furthermore the most important soil and vegetation parameters for predicting soil moisture distribution varied between different grazing intensities. Therefore, predicting soil moisture by using secondary variables requires a careful selection of the soil or vegetation parameters.     

Modelling photo-modulated internode elongation in growing glasshouse cucumber canopies

? Growing glasshouse plant canopies are exposed to natural fluctuations in light quantity, and the dynamically changing canopy architecture induces local variations in light quality. This modelling study aimed to analyse the importance of both light signals for an accurate prediction of individual internode lengths. ? We conceptualized two model approaches for estimating final internode lengths (FILs). The first one is only photosynthetically active radiation (PAR)-sensitive and ignores canopy architecture, whereas the second approach uses a functional-structural growth model for considering variations in both PAR and red : far-red (R : FR) ratio (L-Cucumber). Internode lengths measured in three experiments were used for model parameterization and evaluation. ? The overall trends for the simulated FILs using the exclusively PAR-sensitive model approach were already in line with the measured FILs, but they underestimated FILs at higher ranks. L-Cucumber provided considerably better FIL predictions under various light conditions and canopy architectures. ? Both light signals are needed for an accurate estimation of the FILs, and only L-Cucumber is able to consider R : FR signals from the growing canopy. Yet this study highlights the significance of the PAR signal for predicting FILs as neighbour effects increase, which indicates a potential role of photosynthate signalling in internode elongation.     

Seed-dispersal distributions by trumpeter hornbills in fragmented landscapes

Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investigated movement and seed-dispersal patterns of trumpeter hornbills (Bycanistes bucinator) in a fragmented landscape in South Africa. Novel GPS loggers provide high-quality location data without bias against recording long-distance movements. We found a very weakly bimodal seed-dispersal distribution with potential dispersal distances up to 14.5 km. Within forest, the seed-dispersal distribution was unimodal with an expected dispersal distance of 86 m. In the fragmented agricultural landscape, the distribution was strongly bimodal with peaks at 18 and 512 m. Our results demonstrate that seed-dispersal distributions differed when birds moved in different habitat types. Seed-dispersal distances in fragmented landscapes show that transport among habitat patches is more frequent than previously assumed, allowing plants to disperse among habitat patches and to track the changing climatic conditions.     

Synthesis, conformation and biology of naphthoxylosides

Proteoglycans (PG) are polyanionic proteins consisting of a core protein substituted with carbohydrate chains, that is, glycosaminoglycans (GAG). The biosynthesis of GAG can be manipulated by simple xylosides carrying hydrophobic aglycons, which can enter the cell and initiate the biosynthesis. While the importance of the aglycon is well investigated, there is far less information on the effect of modifications in the xylose residue. We have developed a new synthetic protocol, based on acetal protection and selective benzylation, for modification of the three hydroxyl groups in xylose. Thus we have synthesized twelve analogs of 2-naphthyl β-d-xylopyranoside (XylNap), where each hydroxyl group has been epimerized or replaced by methoxy, fluoro, or hydrogen. To gain more information about the properties of xylose, conformational studies were made on some of the analogs. It was found that the (4)C(1) conformation is highly predominant, accompanied by a nonnegligible population of the (2)S(0) conformation. However, deoxygenation at C3 results in a large portion of the (1)C(4) conformation. The GAG priming ability and proliferation activity of the twelve analogs, were investigated using a matched pair of human breast fibroblasts and human breast carcinoma cells. None of the analogs initiated the biosynthesis of GAG, but an inhibitory effect on endogenous PG production was observed for analogs fluorinated or deoxygenated at C4. From our data it seems reasonable that all three hydroxyl groups in XylNap are essential for the priming of GAG chains and for selective toxicity for tumor cells.     

Different apparent CO2 compensation points in nitrate- and ammonium-grown Phaseolus vulgaris and the relationship to non-photorespiratory CO2 evolution

The classical theory of the relationship between gas fluxes and photosynthetic electron fluxes was extended by two additional terms: J_L describing flux to electron sinks other than the Calvin cycle, and R_L accounting for light-induced changes in non-photorespiratory CO₂ evolution. R_L comprises two main components, R_r resulting from light-induced decrease in tricarboxylic acid activity, and R_S related to extra CO₂ evolution resulting from citrate-to-2-oxoglutarate conversion for N-assimilation in NO₃^– grown leaves. This extended theory was applied to two experiments. First, A–C_i curves (dependence of CO₂ flux on stomatal CO₂ concentration) revealed a higher apparent CO₂ compensation point (Γ*_app) in NO₃^–-grown plants than in NH₄⁺-grown plants. Secondly, photosynthetic electron fluxes at different light intensities were determined by means of the Genty parameter of chlorophyll fluorescence and compared with those calculated from measured CO₂ uptake. Curve-fitting based on the extended theory provided a coincidence of these two measurements and resulted in higher R_S in NO₃^–-grown than in NH₄⁺-grown plants. This difference in R_S (about 15% of the CO₂ flux bound by carboxylation) is the same as that obtained from the analysis of Γ*_app. Further, the analysis suggests that J_L related to the extra electron flux used for N-assimilation in NO₃^–-grown plants is diverted to other sinks in NH₄⁺-grown plants. SHAM decreased photosynthetic electron flow and O₂ evolution in NH₄⁺-grown plants, antimycin A in NO₃^–-grown plants. The effect of oligomycin was small. The results are discussed in terms of different mechanisms of chloroplast/mitochondrion interaction in NO₃^–- and NH₄⁺-grown plants, their effects on non-photorespiratory CO₂ evolution and on Γ*_app.     

Life-history of two African Sylvia warblers: low annual fecundity and long post-fledging care

The investigation of factors that cause differences in life-history traits between temperate and tropical birds is often hampered by a lack of knowledge about tropical species. Even within the well-known warblers of the genus Sylvia , which include resident species from temperate and tropical regions as well as migrants, there are few data from tropical species. We investigated the breeding biology of the tropical species Sylvia lugens and S. boehmi in a 2-year study in Kenya. Both species had a clutch size of 2.0 and laid c.  3.7 clutches per year. Breeding was characterized by long incubation periods ( S. lugens 14.5 days, S. boehmi 15.0 days), long nestling periods (16.0 and 12.9 days, respectively) and high predation rates (Mayfield nest success S. lugens 33.2%, S. boehmi 19.4%). Annual fecundity was 2.3 fledglings in S. lugens and 1.4 fledglings in S. boehmi . After fledging, the young birds were fed for 37.5 days ( S. lugens ) and 58.5 days ( S. boehmi ) (time to independence) and they stayed in their parents' territory for days or weeks, even after feeding had stopped. Fledgling survival until independence was 55.4% in S. lugens and 69.2% in S. boehmi . In general, S. lugens and S. boehmi have smaller but more numerous clutches, longer developmental periods, higher nest predation rates, lower annual fecundity and longer post-fledging care than their temperate congenerics.