Health monitoring of plants by their emitted volatiles: A temporary increase in the concentration of nethyl salicylate after pathogen inoculation of tomato plants at greenhouse scale

This paper describes a method to alert growers of the presence of a pathogen infection in their greenhouse based on the detection of pathogen-induced emissions of volatile organic compounds (VOCs) from plants. Greenhouse-grown plants were inoculated with spores of a fungus to learn more about this concept. The specific objective of the present study was to determine whether VOCs are detectable after inoculation, and if so, to determine the time course of the concentrations of these compounds. To achieve this objective, we inoculated 60 greenhouse-grown tomato plants (Lycopersicon esculentum) with an aqueous suspension of Botrytis cinerea spores. Upon inoculation, the greenhouse air was sampled semi-continuously with a one hour time interval until 72 hours after inoculation (HAI). The samples were transferred to the laboratory and analysed using gas chromatography - mass spectrometry. Ten leaves were randomly selected to monitor the visible symptoms of infection. The severity of these visual symptoms was assessed at 0, 24, 48, and 72 HAI. Results demonstrated no detection of C6-compounds, and an almost constant concentration of all monoterpenes, most sesquiterpenes, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. However, the concentration of methyl salicylate increased 10-fold and 3-fold at 32 and 34 HAI respectively. At 24 HAI, 10% of the selected leaves showed mild symptoms while 20% of the selected leaves showed mild symptoms at 48 HAI. These results indicate that methyl salicylate might alert a grower of the presence of a B. cinerea infection of tomato plants at greenhouse scale. Further research is required to confirm these findings

A method to detect baseline emission and plant damage induced volatile emission in a greenhouse

The objective of this research was to ascertain if 1) baseline emission and 2) damage induced emission of volatile plant substances could be detected under greenhouse conditions. A laboratory method was validated for analysing the air in a semi-closed greenhouse with 44 m2 floor area. This greenhouse, with a volume of 270 m3, was climate controlled and light was supplied with assimilation lamps. Sixty tomato plants (Lycopersicon esculentum Mill cv. Moneymaker) were grown in this greenhouse. These plants were artificially damaged on a weekly interval by stroking the stems. Continuous flow pumps were used to purge the air surrounding the plants through tubes containing an adsorbent. This sampling step was performed before and directly after damage of the plants. After sampling, the tubes were transferred to the lab for analysis. The analysis of volatile compounds was performed using a high-throughput gas chromatography-mass spectrometry system. The method enabled the detection of baseline level emission and the emission of volatiles released after artificially damaging the tomato plants during a 6 weeks growing period. Most dominant compounds for baseline emission were the monoterpenes ß-phellandrene, 2-carene, limonene, ¿-phellandrene and ¿-pinene. Directly after damage, these compounds showed an increase of up to 100 times compared to baseline level emission. With these results, we prove that it is possible to detect baseline- and plant damage induced volatile emission in a greenhouse. This area of research is promising but more research needs to be done to determine whether it is possible to detect plant damage due to pests and pathogens using volatile sensing

One-year follow-up effects of two obesity treatments on psychological well-being and weight.

Objectives. The effectiveness of a cognitive and a behavioural treatment for obese binge eaters and obese non-binge eaters was evaluated at I-year follow-up. Furthermore, we examined the role of weight changes on psychological well-being at I-year follow-up. Design and method. Participants were reassessed 6 months and I year after they had finished a group cognitive treatment or a group behavioural treatment. The outcome measures were; psychological well-being (concerns about shape, weight and eating, self-esteem and depression), binge eating, and weight. Results and conclusions. Analyses on the completers' sample revealed that both treatments had a markedly positive and lasting impact on shape concern, weight concern and eating concern, binge eating, self-esteem, and depression at 1-year followup. Cognitive treatment was not superior to behavioural treatment on most outcome measures. This might be due to selective drop-out, Analyses including non-responders showed that the cognitive treatment was superior on shape, weight and eating concern, and binge eating. The I-year follow-up results for weight-loss were disappointing. Between pre-treatment and 1-year follow-up participants in the behaviour treatment lost 3.0 kg, while participants in the cognitive treatment lost 0.3 kg. However, participants who gained weight were as successful on changes in psychological well-being changes as participants who lost weight

Anterior-posterior axis formation in Xenopus laevis

The research described in this thesis mainly focussed on making and refining a model that describes axial patterning during gastrulation in the frog Xenopus laevis. Chapter 2 and 3 describe that axial information arises in the mesoderm and subsequently in the neurectoderm. Also is shown that this information, under influence of the Spemann organiser and cellular movements, is translated from a time sequence into a space sequence. The function of the Spemann organiser, important for AP patterning is neural induction. In chapter 4 is described that retinoids, important for axial patterning and formed in the mesoderm, have a patterning effect on neurectoderm. An important conclusion in this chapter is that retinoids are candidates for transfer of axial information from mesoderm to neurectoderm and can, in this way, coordinate the expression of axial information between mesoderm and neurectoderm. In chapter 5 a study is described where the transcriptional targets of Hoxc6 or Antennapedia in the frog Xenopus laevis and the fruitfly Drosophila melanogaster are compared. From this comparison conclusions can be drawn about the processes that are important for the function of Hoxc6/Antp. From this study could be concluded that celldivision, cellmigration, and suppresion of head formation are processes that are important for the function of Hoxc6/Antp.LEI Universiteit LeidenAnimal science

Is Twitter a Public Sphere for Online Conflicts? A Cross-Ideological and Cross-Hierarchical Look

The rise in popularity of Twitter has led to a debate on its impact on public opinions. The optimists foresee an increase in online participation and democratization due to social media's personal and interactive nature. Cyber-pessimists, on the other hand, explain how social media can lead to selective exposure and can be used as a disguise for those in power to disseminate biased information. To investigate this debate empirically, we evaluate Twitter as a public sphere using four metrics: equality, diversity, reciprocity and quality. Using these measurements, we analyze the communication patterns between individuals of different hierarchical levels and ideologies. We do this within the context of three diverse conflicts: Israel-Palestine, US Democrats-Republicans, and FC Barcelona-Real Madrid. In all cases, we collect data around a central pair of Twitter accounts representing the two main parties. Our results show in a quantitative manner that Twitter is not an ideal public sphere for democratic conversations and that hierarchical effects are part of the reason why it is not.Comment: To appear in the 6th International Conference on Social Informatics (SocInfo 2014), Barcelon