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Multiple Environmental Variables Affect Germination and Mortality of an Annual Salt Marsh Pioneer: Salicornia procumbens
No full textSalt marshes, providing numerous ecosystem services, are degrading worldwide. To effectively aid conservation and restoration efforts, increased knowledge on marsh expansion processes and the initial establishment of pioneer vegetation is essential. In this study, we disentangle environmental drivers that affect the lifecycle of the annual pioneer Salicornia procumbens at the salt marsh edge. We studied the effect of various environmental variables on the start of germination, germination success and mortality before seed-set in a field experiment in the DutchWadden Sea atWesthoek. Our results indicate that temperature and sedimentation inhibited the initiation of germination. Once germination occurred, higher precipitation rates increased germination success. In contrast,sedimentation rates above 0.5 mm day−1 halved germination success through burial of freshly sprouted seedlings. Unexpectedly, natural germination was low, indicating that seed availability may have been limited, despite a seed source nearby. Frequent inundation, extended periods without inundation (through desiccation of the soil) and a highly dynamic bed level increased mortality beforeseed-set. Consequently, bed-level dynamics (erosion, sedimentation and bed-level variation) impact seed production dually (decrease germination and increase mortality) and thus potentially reproduction success. A high seed reproduction is crucial for annuals, such as S. procumbens, to re-establish the following year. Next to advancing our general knowledge of natural salt marsh expansion, results in this study can also be used to assess the potential of a given site for saltmarsh stimulation or restoration. Seed availability and local bedlevel dynamics are key in the successful establishment of a salt marsh pioneer: Salicornia procumbens
Application of headspace solid-phase micro-extraction gas chromatography for the assessment of the volatiles profiles of ultra-high temperature hydrolysed-lactose milk during production and storage
No full textUHT hydrolysed-lactose milk (HLM) is prone to chemical changes, giving rise to off-flavours in the product. To investigate this better, headspace solid-phase micro-extraction gas chromatography (HS-SPME/GC–MS) was applied to monitor the volatiles profile of HLM during production and shelf-life. Optimum extraction conditions for volatiles were explored, focussing on compounds affecting milk aroma. This study is the first investigating industrial scale manufacturing under controlled conditions, allowing direct associations between specific reactions and changes in milk volatiles. The effect of UHT treatment on milk flavour was shown, while the lactase, potentially containing undesirable proteases and odours, did not alter the milk “volatilome” after addition. Commercial samples exhibited different trends in the volatiles along the shelf-life due to differences in production systems, lactase purity and packaging. Merging all results, HS-SPME/GC–MS successfully mapped the phenomena causing modifications in the volatiles profile of UHT HLM at each step of the product life-cycle.</p
Microtechnological Tools to Achieve Sustainable Food Processes, Products, and Ingredients
No full textOne of the major challenges we face as humankind is supplying a growing world population with sufficient and healthy foods. Although from a worldwide perspective sufficient food is produced, locally, the situation can be dire. Furthermore, the production needs to be increased in a sustainable manner for future generations, which also implies prevention of food waste, and making better use of the available resources. How to contribute to this as food technologists is an ultimate question, especially since the tools that can investigate processes at relevant time scales, and dimensions, are lacking. Here we propose the use of microtechnology and show examples of how this has led to new insights in the fields of ingredient isolation (filtration), and emulsion/foam formation, which will ultimately lead to better-defined products. Furthermore, microfluidic tools have been applied for testing ingredient functionality, and for this, various examples are discussed that will expectedly contribute to making better use of more sustainably sourced starting materials (e.g., novel protein sources). This review will wrap up with a section in which we discuss future developments. We expect that it will be possible to link food properties to the effects that foods create in vivo. We thus expand the scope of this review that is technical in nature, toward physiological functionality, and ultimately to rational food design that is targeted to improve human health.</p
Quantitative mapping of lignin : Comprehensive insight into fungal delignification of plant biomass
No full textPlant biomass delignification is crucial for terrestrial carbon cycling and is essential for incentives aiming at the valorization of lignocellulose. For understanding this central process in nature and biorefinery, we need to elucidate and comprehend the mechanisms that govern recalcitrance and conversion at the molecular level. This insight can only be obtained by accurate analysis of the molecules involved, both contentwise and structurewise. This research, therefore, aimed to advance the quantitative mapping of lignin and employ the developed analytical toolkit to unravel the underlying mechanisms of a process that has largely remained elusive to date: the fungal delignification of plant biomass. We demonstrate through careful method validation that py-GC-MS analysis can be used for the concurrent quantification and structural characterization of grass, hardwood and softwood lignin, when employing uniformly 13C labeled lignin internal standards and relative response factors for the individual pyrolysis products. The developed method was used to assess three white-rot fungal species in terms of delignification effectivity and selectivity. In both important traits, Ceriporiopsis subvermispora outperformed Lentinula edodes and Pleurotus eryngii. Comprehensive structural analyses of the residual lignin after growth of C. subvermispora allowed us to reconstruct various degradation routes of lignin’s most abundant β-O-4’ ethers and determine the relative susceptibility of various β-O-4’ substructures. Our results imply that one-electron oxidation initiates in situ ligninolysis, which then cascades into the cleavage of Ca-Cb, Cb-O and O-4’-aryl bonds. Ligninolysis was shown to depend on the electron density of the 4’-O­-subunit, diastereochemistry and γ-acylation. In addition to white-rot basidiomycete fungi, we studied the ligninolytic capacity of the ascomycete fungus P. anserina. Substrate characterization unambiguously confirmed lignin degradation and secretome analysis suggested that laccases and H2O2 producing enzymes were likely involved in the observed ligninolysis
Resilience of River Deltas in the Anthropocene
No full textAt a global scale, delta morphologies are subject to rapid change as a result of direct and indirect effects of human activity. This jeopardizes the ecosystem services of deltas, including protection against flood hazards, facilitation of navigation, and biodiversity. Direct manifestations of delta morphological instability include river bank failure, which may lead to avulsion, persistent channel incision or aggregation, and a change of the sedimentary regime to hyperturbid conditions. Notwithstanding the in-depth knowledge developed over the past decades about those topics, existing understanding is fragmented, and the predictive capacity of morphodynamic models is limited. The advancement of potential resilience analysis tools may proceed from improved models, continuous observations, and the application of novel analysis techniques. Progress will benefit from synergy between approaches. Empirical and numerical models are built using field observations, and, in turn, model simulations can inform observationists about where to measure. Information theory offers a systematic approach to test the realism of alternative model concepts. Once the key mechanism responsible for a morphodynamic instability phenomenon is understood, concepts from dynamic system theory can be employed to develop early warning indicators. In the development of reliable tools to design resilient deltas, one of the first challenges is to close the sediment balance at multiple scales, such that morphodynamic model predictions match with fully independent measurements. Such a high ambition level is rarely adopted and is urgently needed to address the ongoing global changes causing sea level rise and reduced sediment input by reservoir building.</p
Improved Understanding of the Link Between Catchment-Scale Vegetation Accessible Storage and Satellite-Derived Soil Water Index
No full textThe spatiotemporal dynamics of water volumes stored in the unsaturated root zone are a key control on the response of terrestrial hydrological systems. Robust, catchment-scale root-zone soil moisture estimates are thus critical for reliable predictions of river flow, groundwater recharge, or evaporation. Satellites provide estimates of near-surface soil moisture that can be used to approximate the moisture content in the entire unsaturated root zone through the Soil Water Index (SWI). The characteristic time length (T, in days), as only parameter in the SWI approach, characterizes the temporal variability of soil moisture. The factors controlling T are typically assumed to be related to soil properties and climate; however, no clear link has so far been established. In this study, we hypothesize that optimal T values (Topt) are linked to the interplay of precipitation and evaporation during dry periods, thus to catchment-scale vegetation accessible water storage capacities in the unsaturated root zone. We identify Topt by matching modeled time series of root-zone soil moisture from a calibrated process-based hydrological model to SWI from several satellite-based near-surface soil moisture products in 16 contrasting catchments in the Meuse river basin. Topt values are strongly and positively correlated with vegetation accessible water volumes that can be stored in the root zone, here estimated for each study catchment both as model calibration parameter and from a water-balance approach. Differences in Topt across catchments are also explained by land cover (% agriculture), soil texture (% silt), and runoff signatures (flashiness index).</p
Bouwstenen voor nieuw stikstofbeleid
No full textMomenteel is de vergunningverlening gebaseerd op een toelaatbare toename van de stikstof-depositie op een nabijgelegen natuurgebied. Dat beleid is ingewikkeld en om meer redenen niet optimaal. Het is zinvol om de focus te verleggen van lokaal depositiebeleid naar meer generiek emissiebeleid, met daarin opgenomen het realiseren van een nationaal emissieplafond in 2030 en 2050. Dit sluit aan op de systematiek van het klimaatakkoord en is bestuurlijk en juridisch beter te verdedigen. Het haalt bovendien de overmatige aandacht weg van economische activiteiten rondom Natura 2000-gebieden en zal positief uitpakken voor de natuur
Microfluidic chip for culturing intestinal epithelial cell layers: Characterization and comparison of drug transport between dynamic and static models
No full textDynamic flow in vitro models are currently widely explored for their applicability in drug development research. The application of gut-on-chip models in toxicology is lagging behind. Here we report the application of a gut-on-chip model for biokinetic studies and compare the observed biokinetics of reference compounds with those obtained using a conventional static in vitro model. Intestinal epithelial Caco-2 cells were cultured on a porous membrane assembled between two glass flow chambers for the dynamic model, or on a porous membrane in a Transwell model. Confocal microscopy, lucifer yellow translocation, and alkaline phosphatase activity evaluation revealed that cells cultured in the gut-on-chip model formed tight, differentiated, polarized monolayers like in the static cultures. In the dynamic gut-on-chip model the transport of the high permeability compounds antipyrine, ketoprofen and digoxin was lower (i.e. 4.2-, 2.7- and 1.9-fold respectively) compared to the transport in the static Transwell model. The transport of the low permeability compound, amoxicillin, was similar in both the dynamic and static in vitro model. The obtained transport values of the compounds are in line with the compound Biopharmaceuticals Classification System. It is concluded that the gut-on-chip provides an adequate model for transport studies of chemicals.</p
Carbon-nitrogen interactions in European forests and semi-natural vegetation - Part 2 : Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials
No full textThe effects of atmospheric nitrogen deposition (Ndep) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of Ndep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dryCwet) reactive nitrogen (Nr) deposition.We propose a methodology for untangling the effects of Ndep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO2 exchange fluxes from a Europe-wide network of 22 forest flux towers. Total Nr deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition (dNEP= dNdep) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP=dNdep value. This model-enhanced analysis of the C and Ndep flux observations at the scale of the European network suggests a mean overall dNEP= dNdep response of forest lifetime C sequestration to Ndep of the order of 40 50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus Ndep were non-linear, with no further growth responses at high Ndep levels (Ndep >2.5 3 gNm2 yr1) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high Ndep levels implies that the forecast increased Nr emissions and increased Ndep levels in large areas of Asia may not positively impact the continent s forest CO2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC=dN response.</p