Metabolic fingerprinting to assess the impact of salinity on carotenoid content in developing tomato fruits

As the presence of health-promoting substances has become a significant aspect of tomato fruit appreciation, this study investigated nutrient solution salinity as a tool to enhance carotenoid accumulation in cherry tomato fruit (Solanum lycopersicum L. cv. Juanita). Hereby, a key objective was to uncover the underlying mechanisms of carotenoid metabolism, moving away from typical black box research strategies. To this end, a greenhouse experiment with five salinity treatments (ranging from 2.0 to 5.0 decisiemens (dS) m(-1)) was carried out and a metabolomic fingerprinting approach was applied to obtain valuable insights on the complicated interactions between salinity treatments, environmental conditions, and the plant's genetic background. Hereby, several hundreds of metabolites were attributed a role in the plant's salinity response (at the fruit level), whereby the overall impact turned out to be highly depending on the developmental stage. In addition, 46 of these metabolites embraced a dual significance as they were ascribed a prominent role in carotenoid metabolism as well. Based on the specific mediating actions of the retained metabolites, it could be determined that altered salinity had only marginal potential to enhance carotenoid accumulation in the concerned tomato fruit cultivar. This study invigorates the usefulness of metabolomics in modern agriculture, for instance in modeling tomato fruit quality. Moreover, the metabolome changes that were caused by the different salinity levels may enclose valuable information towards other salinity-related plant processes as well

The central role of modern analytical tools in studying the link between oceans & human health

A plethora of human activities (e.g. industrial processes, domestic households and agriculture) severely impacts our marine environment, and as a result thereof also human health. In this context, it is essential to acquire valuable insights on 1) the presence of potentially bioactive residues, contaminants and toxins in our marine environment originating from human activities, 2) the uptake, bioaccumulation and metabolisation of these bioactive substances by edible aquatic species, and 3) the health risks or benefits associated with human exposure to these substances and their conjugates. New tools for monitoring (i.e. passive samplers) as well as high-end analytical instrumentation (i.e. high-resolution mass spectrometry for profiling and fingerprinting) are indispensable to acquire a correct view on the status of the marine environment and its impact on human health. In this presentation, several practical examples will be shared that demonstrate this

Application of drought and salt stress can improve tomato fruit quality without jeopardising production

High-tech tomato greenhouse systems, which are the standard in Northern Europe (especially in Belgium and the Netherlands), mainly aim for high yields, up to 60 kg m-2. However, quality should be considered equally important, as consumers are willing to pay higher prices per kg for a high quality product. Influencing the plant water status is acknowledged to strongly influence fruit quality, as water deficit or increased salinity may result in higher dry matter content, a main determinant of tomato quality. Unfortunately, this increase in quality is often associated with a decrease in fresh yield, making a thorough insight on the controlling factors of both aspects critical if one aspires to optimise the final product value. The objective of the current research was therefore to combine plant water status monitoring with the assessment of an array of fruit quality parameters and yield, for both drought and salinity treatments in order to further clarify this interrelationship. To this end, we set up an experiment in a controlled greenhouse environment, where tomato plants (Solanum lycopersicum 'Dirk') were exposed to four different treatments: control, drought stress, and two levels of salt stress (EC levels of 4 and 6 dS cm-1). Plant water status was monitored by measuring stem water potential. Furthermore, fruit yield, as well as a set of fruit quality parameters (hexose sugars content, organic acids content, and firmness) was evaluated. Results showed that fruit quality does benefit from both drought and increased salinity, and that the highest salinity level scored the best on all measured quality aspects. Moreover, we observed that even small water deficits, induced either by mild drought or salt stress, improved fruit quality, without jeopardising yield. The acquired insights, combined with mechanistic modelling, may ultimately lead to a more efficient greenhouse management with higher quality tomatoes

UHPLC-HRMS based targeted and untargeted screening of plasticizers in the marine environment

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Metabolomic analysis of cricket paralysis virus infection in Drosophila S2 cells reveals divergent effects on central carbon metabolism as compared with silkworm Bm5 cells

High-throughput approaches have opened new opportunities for understanding biological processes such as persistent virus infections, which are widespread. However, the potential of persistent infections to develop towards pathogenesis remains to be investigated, particularly with respect to the role of host metabolism. To explore the interactions between cellular metabolism and persistent/pathogenic virus infection, we performed untargeted and targeted metabolomic analysis to examine the effects of Cricket paralysis virus (CrPV, Dicistroviridae) in persistently infected silkworm Bm5 cells and acutely infected Drosophila S2 cells. Our previous study (Viruses 2019, 11, 861) established that both glucose and glutamine levels significantly increased during the persistent period of CrPV infection of Bm5 cells, while they decreased steeply during the pathogenic stages. Strikingly, in this study, an almost opposite pattern in change of metabolites was observed during different stages of acute infection of S2 cells. More specifically, a significant decrease in amino acids and carbohydrates was observed prior to pathogenesis, while their abundance significantly increased again during pathogenesis. Our study illustrates the occurrence of diametrically opposite changes in central carbon mechanisms during CrPV infection of S2 and Bm5 cells that is possibly related to the type of infection (acute or persistent) that is triggered by the virus

Metabolomics-based biomarker discovery for bee health monitoring : a proof of concept study concerning nutritional stress in Bombus terrestris

Bee pollinators are exposed to multiple natural and anthropogenic stressors. Understanding the effects of a single stressor in the complex environmental context of antagonistic/synergistic interactions is critical to pollinator monitoring and may serve as early warning system before a pollination crisis. This study aimed to methodically improve the diagnosis of bee stressors using a simultaneous untargeted and targeted metabolomics-based approach. Analysis of 84 Bombus terrestris hemolymph samples found 8 metabolites retained as potential biomarkers that showed excellent discrimination for nutritional stress. In parallel, 8 significantly altered metabolites, as revealed by targeted profiling, were also assigned as candidate biomarkers. Furthermore, machine learning algorithms were applied to the above-described two biomarker sets, whereby the untargeted eight components showed the best classification performance with sensitivity and specificity up to 99% and 100%, respectively. Based on pathway and biochemistry analysis, we propose that gluconeogenesis contributed significantly to blood sugar stability in bumblebees maintained on a low carbohydrate diet. Taken together, this study demonstrates that metabolomics-based biomarker discovery holds promising potential for improving bee health monitoring and to identify stressor related to energy intake and other environmental stressors