Vitamin D and skeletal muscle structure and function

Haan, A. de [Promotor]Rittweger, J. [Promotor]Degens, H. [Copromotor]Jaspers, R.T. [Copromotor

Phenotyping tomato root developmental plasticity in response to salinity in soil rhizotrons

Plants have developed multiple strategies to respond to salt stress. In order to identify new traits related to salt tolerance, with potential breeding application, the research focus has recently been shifted to include root system architecture (RSA) and root plasticity. Using a simple but effective root phenotyping system containing soil (rhizotrons), RSA of several tomato cultivars and their response to salinity was investigated. We observed a high level of root plasticity of tomato seedlings under salt stress. The general root architecture was substantially modified in response to salt, especially with respect to position of the lateral roots in the soil. At the soil surface, where salt accumulates, lateral root emergence was most strongly inhibited. Within the set of tomato cultivars, H1015 was the most tolerant to salinity in both developmental stages studied. A significant correlation between several root traits and aboveground growth parameters was observed, highlighting a possible role for regulation of both ion content and root architecture in salt stress resilience

Roots Withstanding their Environment: Exploiting Root System Architecture Responses to Abiotic Stress to Improve Crop Tolerance

To face future challenges in crop production dictated by global climate changes, breeders and plant researchers collaborate to develop productive crops that are able to withstand a wide range of biotic and abiotic stresses. However, crop selection is often focused on shoot performance alone, as observation of root properties is more complex and asks for artificial and extensive phenotyping platforms. In addition, most root research focuses on development, while a direct link to the functionality of plasticity in root development for tolerance is often lacking. In this paper we review the currently known root system architecture (RSA) responses in Arabidopsis and a number of crop species to a range of abiotic stresses, including nutrient limitation, drought, salinity, flooding, and extreme temperatures. For each of these stresses, the key molecular and cellular mechanisms underlying the RSA response are highlighted. To explore the relevance for crop selection, we especially review and discuss studies linking root architectural responses to stress tolerance. This will provide a first step toward understanding the relevance of adaptive root development for a plant's response to its environment. We suggest that functional evidence on the role of root plasticity will support breeders in their efforts to include root properties in their current selection pipeline for abiotic stress tolerance, aimed to improve the robustness of crops

The societal roles and responsibilities of plant scientists in the context of genome-edited crops

Societal Impact Statement The societal debate on the use of genome-edited crops has been polarised from the start. While policymakers struggle to democratically resolve this dilemma, plant scientists have been criticised for taking up advocative roles and thereby risking further polarisation. This study demonstrates how plant scientists themselves perceive their roles and responsibilities. Indeed, those scientists active in the debate were found to fulfil advocative roles, and there seems to be an underlying, persistent?and very traditional?view on roles and responsibilities of scientists within the community. Critical reflection on this view is required for better democratic dialogue and decision-making. More interdisciplinary interaction could facilitate this reflection. Summary In this paper, we examine how plant scientists from Wageningen University and Research (WUR) demarcate their roles and responsibilities in relation to the societal impact of their research, in response to calls for public legitimacy of their research, and within the societal debate on the governance of genome-edited crops (GE crops) in Europe. We analysed 16 semi-structured interviews, 5-day journals, and (social) media contributions of plant scientists at WUR. Our study demonstrates that the perceived roles and responsibilities of the interviewees were aligned with the ideal of the scientist as value-free, as separate from society, and as producing knowledge that leads to unproblematic societal benefits through industry. When confronted with the polarised debate on the governance of genome editing (GE) technology, the reflexivity that our respondents had demonstrated in general, tended to be dispersed. Respondents rarely considered the GE crop debate, or their own position, to be value-based. Those respondents active in the debate were found to fulfil advocative roles, and they struggled to recognise the validity of viewpoints other than their own. We hypothesise that this decreased reflexive capacity is a product of the long-term polarisation of the GM/GE debate, mediated by both their conceptual alignment with the linear model of innovation and their limited interactions outside of their field. In order to better align the perspectives of social and natural scientists on the topic of science-responsibility, and to constructively contribute to the debate on GE crops, we argue for more interaction between the these two communities

Replacement of Retinyl Esters by Polyunsaturated Triacylglycerol Species in Lipid Droplets of Hepatic Stellate Cells during Activation

Activation of hepatic stellate cells has been recognized as one of the first steps in liver injury and repair. During activation, hepatic stellate cells transform into myofibroblasts with concomitant loss of their lipid droplets (LDs) and production of excessive extracellular matrix. Here we aimed to obtain more insight in the dynamics and mechanism of LD loss. We have investigated the LD degradation processes in rat hepatic stellate cells in vitro with a combined approach of confocal Raman microspectroscopy and mass spectrometric analysis of lipids (lipidomics). Upon activation of the hepatic stellate cells, LDs reduce in size, but increase in number during the first 7 days, but the total volume of neutral lipids did not decrease. The LDs also migrate to cellular extensions in the first 7 days, before they disappear. In individual hepatic stellate cells. all LDs have a similar Raman spectrum, suggesting a similar lipid profile. However, Raman studies also showed that the retinyl esters are degraded more rapidly than the triacylglycerols upon activation. Lipidomic analyses confirmed that after 7 days in culture hepatic stellate cells have lost most of their retinyl esters, but not their triacylglycerols and cholesterol esters. Furthermore, we specifically observed a large increase in triacylglycerol-species containing polyunsaturated fatty acids, partly caused by an enhanced incorporation of exogenous arachidonic acid. These results reveal that lipid droplet degradation in activated hepatic stellate cells is a highly dynamic and regulated process. The rapid replacement of retinyl esters by polyunsaturated fatty acids in LDs suggests a role for both lipids or their derivatives like eicosanoids during hepatic stellate cell activation