Spatial heterogeneity in plant-soil feedbacks alters competitive interactions between two grassland plant species

Plant science

Amphiphilic poly(ether ester amide) multiblock copolymers as biodegradable matrices for the controlled release of proteins

Amphiphilic poly(ether ester amide) (PEEA) multiblock copolymers were synthesized by polycondensation in the melt from hydrophilic poly(ethylene glycol) (PEG), 1,4-dihydroxybutane and short bisester-bisamide blocks. These amide blocks were prepared by reaction of 1,4-diaminobutane with dimethyl adipate in the melt. A range of multiblock copolymers were prepared, with PEG contents varying from 23-66 wt %. The intrinsic viscosity of the PEEA polymers varied from 0.58-0.78. Differential scanning calorimetry showed melting transitions for the PEG blocks and for the amide-ester blocks, suggesting a phase separated structure. Both the melting temperature and the crystallinity of the hard amide-ester segments decreased with increasing PEG content of the polymers. The equilibrium swelling ratio in phosphate buffered saline (PBS) increased with increasing amount of PEG in the polymers and varied from 1.7 to 3.7, whereas the polymer that contained 66 wt % PEG was soluble in PBS. During incubation of PEEA films in PBS, weight loss and a continuous decrease in the resulting inherent polymer viscosity was observed. The rate of degradation increased with increasing PEG content. The composition of the remaining matrices did not change during degradation. A preliminary investigation of the protein release characteristics of these PEEA copolymers showed that release of the model protein lysozyme was proportional to the square root of time. The release rate was found to increase with increasing degree of swelling of the polymers

Light condition experienced by parent plants influences the response of offspring to light via both parental effects and soil legacy effects

1. Environmental conditions experienced by parent plants can influence offspring performance through parental effects induced by DNA methylation. The offspring can also be influenced by environmental conditions experienced by their parents via soil legacy effects due to plant-mediated changes in the composition of soil microbes. These two effects are likely to act simultaneously, but empirical evidence for combined effects is limited.2. We conducted a two-phase experiment with five genotypes of a clonal plant Hydrocotyle vulgaris. In the first phase, we grew parent plants of each genotype under two light conditions (ambient vs. shade) and two DNA demethylation treatments (treated with water vs. 5-azacytidine). We then collected soils and clonal offspring for each genotype from each of these four treatments and measured soil (a)biotic properties. In the second phase, we grew the offspring from each of the four treatments in the four different soils, under the two light conditions.3. When grown under ambient light condition and in soil from ambient parents, offspring produced by ambient parents grew larger than offspring produced by shaded parents when the parents were treated with water. This difference was smaller when the parents were treated with 5-azacytidine, and disappeared when the offspring were grown in soil from shaded parents. The growth difference was also observed when the offspring were grown under shaded condition and in soil from shaded parents. However, this difference was greater when the parents were treated with 5-azacytidine, and disappeared when the offspring were grown in soil from ambient parents. Moreover, offspring growth was associated with fungal composition and total phosphorus of the soil in which the parents had grown.4. Our results show, for the first time, that light condition experienced by parents can influence offspring responses to light through both parental effects and soil legacies. The parental effects were mediated by changes in DNA methylation and the soil legacies were due to plant-mediated changes in a combination of soil biotic and abiotic properties. These impacts may eventually influence the ecological and evolutionary trajectories of clonal plant populations.Plant science

Conditioning the soil microbiome through plant–soil feedbacks suppresses an aboveground insect pest

Plant science

Single introductions of soil biota and plants generate long-term legacies in soil and plant community assembly

Recent demonstrations of the role of plant-soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long-term consequences of plant- soil interactions for above-belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one-time additions of soil biota and plant seeds alter soil-borne nematode and plant community composition in semi-natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long-lasting impact on the trajectory of community assembly

Rapid automatic assessment of microvascular density in sidestream dark field images

The purpose of this study was to develop a rapid and fully automatic method for the assessment of microvascular density and perfusion in sidestream dark field (SDF) images. We modified algorithms previously developed by our group for microvascular density assessment and introduced a new method for microvascular perfusion assessment. To validate the new algorithm for microvascular density assessment, we reanalyzed a selection of SDF video clips (n = 325) from a study in intensive care patients and compared the results to (semi-)manually found microvascular densities. The method for microvascular perfusion assessment (temporal SDF image contrast analysis, tSICA) was tested in several video simulations and in one high quality SDF video clip where the microcirculation was imaged before and during circulatory arrest in a cardiac surgery patient. We found that the new method for microvascular density assessment was very rapid (<30 s/clip) and correlated excellently with (semi-)manually measured microvascular density. The new method for microvascular perfusion assessment (tSICA) was shown to be limited by high cell densities and velocities, which severely impedes the applicability of this method in real SDF images. Hence, here we present a validated method for rapid and fully automatic assessment of microvascular density in SDF images. The new method was shown to be much faster than the conventional (semi-)manual method. Due to current SDF imaging hardware limitations, we were not able to automatically detect microvascular perfusion

Changes in litter quality induced by N deposition alter soil microbial communities

Plant science