30 research outputs found
Correction: Pilot-scale cultivation of the snow alga Chloromonas typhlos in a photobioreactor
No full text[This corrects the article DOI: 10.3389/fbioe.2022.896261.]
Pilot-Scale Cultivation of the Snow Alga Chloromonas typhlos in a Photobioreactor
No full textThe most studied and cultivated microalgae have a temperature optimum between 20 and 35°C. This temperature range hampers sustainable microalgae growth in countries with colder periods. To overcome this problem, psychrotolerant microalgae, such as the snow alga Chloromonas typhlos, can be cultivated during these colder periods. However, most of the research work has been carried out in the laboratory. The step between laboratory-scale and large-scale cultivation is difficult, making pilot-scale tests crucial to gather more information. Here, we presented a successful pilot-scale growth test of C. typhlos. Seven batch mode growth periods were compared during two longer growth tests in a photobioreactor of 350 L. We demonstrated the potential of this alga to be cultivated at colder ambient temperatures. The tests were performed during winter and springtime to compare ambient temperature and sunlight influences. The growth and CO(2) usage were continuously monitored to calculate the productivity and CO(2) fixation efficiency. A maximum dry weight of 1.082 g L(−1) was achieved while a maximum growth rate and maximum daily volumetric and areal productivities of 0.105 d(−1), 0.110 g L(−1) d(−1), and 2.746 g m(−2) d(−1), respectively, were measured. Future tests to optimize the cultivation of C. typhlos and production of astaxanthin, for example, will be crucial to explore the potential of biomass production of C. typhlos on a commercial scale
Onderzoek naar de protease inhibitor geïnduceerde regulatie van de vertering op enzymatisch en transcript niveau in twee sprinkhaansoorten, Schistocerca gregaria en Locusta migratoria
No full textAn important source of alternative insect control proteins is the plant defence system. By millions of years of co-evolution, plants have evolved (some very effective) counter measures to predation by herbivorous insects. Many different plant defensive compounds have been shown to possess some toxic or anti-metabolic effect on insects and hence are considered as possible candidates for the genetic modification of crop plants. Protease inhibitors (PIs) form a group of candidate proteins that have received attention for a long time and are amongst the most advanced in terms of development. PIs target the digestive proteolytic enzymes in the gut of insects. However, frequently, insect adaptation to these anti-nutritional proteins is observed. One of the reasons for this is the large variety of digestive protease genes encoded by insects that can be transcriptionally regulated, thereby compensating for the loss of digestive activity.Little information exists on the digestive enzymes of locusts, especially at the transcript level. Furthermore, to date, our knowledge on insect compensation for PI ingestion is strictly based on studies in a limited number of lepidopteran and coleopteran species. Therefore, the general aim of this thesis was to identify possible PI induced compensatory responses in the gut of the desert locust, Schistocerca gregaria,and the migratory locust, Locusta migratoria, both at the enzyme activity and transcript level. We were able to show that both locust species possess the ability to compensate for the ingestion of PI. ExistingEST databases for L. migratoria were screened for serine protease-like sequences. A total of 5 putative trypsins and 15 putative chymotrypsins could be characterized. The relative gene expression levels of representative members were determined under different feeding conditions. Transcript levels for all measured serine proteases were strongly reduced after starvation. On the other hand, rapid initial upregulation was observed for all tested transcripts after PI ingestion.A microarray based approach was used to identify transcripts that were specifically transcribed in gut, brain, or both tissues. Gut specific transcripts were functionally annotated, and were found to be enriched in transcripts with putative functions closely related to the physiological functions of the gut as a muscular digestive organ, and as the first barrier against micro-organisms and a wide range of toxins. In addition, a second microarray experiment with a selected subset of sequences was conducted, which aimed at revealing underlying transcriptional changes after initial detection of inhibitor presence in the locust midgut. We discovered that several transcripts involved in energy metabolism were quickly altered after PI ingestion. Apart from upregulating digestive proteases, transcripts involved in carbohydrate and lipid metabolism were found to be differentially expressed. In addition, the results suggest that during the physiological challenge of PIingestion, fewer resources are invested in defence, stress responses, and in the maintenance of structural integrity. Furthermore, several transcripts encoding juvenile hormone binding proteins were found to be upregulated. Their involvement in PI compensation in L. migratoria was further assessed using RNA interference.In conclusion, the findings in this thesis contribute to a better understanding of protease inhibitor induced compensatory responses in insects. The fact that also orthopteran insects were able to compensate quickly for ingestion of dietary inhibitors is especially interesting, and suggests that the basic mechanisms responsible for the changes in proteolytic enzyme expression may have arose early in insect evolution. Our results further indicate that for PI to be successful as biopesticides, the insects adaptive mechanisms have to be circumvented, or that a combined approach, simultaneously targeting the digestive system and other vulnerable physiological systems might be preferred.<w:latentstyles deflockedstate="false" defunhidewhenused="true" <w:lsdexception="" locked="false" priority="0" semihidden="false" <w:latentstyles=""status: Publishe
Uptake and degradation of dsRNA in the gut lumen of insects in relation to environmental RNAi efficiency
No full textCompensatory responses to dietary protease inhibitors in the migratory locust, Locusta migratoria
No full textstatus: Publishe
Energy storage in Parkstad
No full textParkstad is planning to power most of its electrical grid by solar energy, resulting in an intermittent power supply. One of the methods to solve this intermittency is to create facilities for energy storage. The landscape differs from the rest of the Netherlands by its hilly profile. The most important difference is presence of a large subterranean infrastructure which is a relic from the mining past. This vast infrastructure holds potential for energy storage. Energy storage demand exists on three levels. Daily storage demand, inter seasonal storage demand and incidental storage demand could benefit from energy storage among other solutions. The actual methods to achieve this energy storage are mechanical, electrochemical, chemical and thermal. For Parkstad compressed air storage, underground pumped hydro and gravitational storage hold potential.Architecture, Urbanism and Building Science
Real-Time Monitoring of Microalgal Biomass in Pilot-Scale Photobioreactors Using Nephelometry
No full textsponsorship: This research was funded by Interreg North-West Europe, Grant No. NWE 639. (Interreg North-West Europe)status: Publishe
Timber Joints: A parametric study on the dimensional interaction between joints and members in timber frame structures
No full textThe importance of joints in timber structures is strongly emphasized in the existing literature (e.g., Blaß & Sandhaas, 2017; McLain, 1998). The aim of this project is to provide insight into whether the cross-sectional sizes of the member are dictated by the dimensional sizes of the laterally loaded dowel-type connection or the strength and stiffness requirements of the member itself in timber frame structures. In this research project, a parametric study is performed. The parameters in this study represent the global frame structure and the laterally loaded dowel-type connections. Together, these parameters form a parametric model that lays the foundation for the tool that is constructed in this study. This tool is built in order to generate a number of unique configurations that fulfill the design verifications. Using the tool, two analyses are performed. In analysis 1, the effect of different distances between the secondary beams is examined. In analysis 2, the effect of different grid sizes of the column in the frame structure is studied. In both analyses, two member sizes are first selected based on the criteria 'lowest cross-sectional area' (LCA) and 'lowest height beam' (LHB). These two member sizes form the starting point for generating different configurations of laterally loaded dowel-type connections. In this research project, three factors are found to contribute to the largest reduction in the number of unique configurations for all constructed cases examined in analysis 1 and 2. These three factors are small column widths combined with high shear forces, the effect of a 'compact' member, and the effect of 'brittle' failure mechanisms on the LCA-members, which was selected as a design constraint in this study. These factors may be relevant for engineers to take into account when designing the structural members.However, in this study, no constructed case is found in which the member needs to be redesigned in order to fit the connection. This means that one can conclude that the dimensional size of the structural member is dictated by the strength and stiffness requirements of the member itself. Important to note is that, although a large number of parameters was incorporated into this study, not all potentially relevant parameters were taken into account. When incorporating factors such as the horizontal forces in the connection, the effect of shrinkage and swelling, the level of difficultly in terms of assembling the joints on site, and adjustments to guarantee a certain level of fire resistance, certain turning points in the dimensional interaction between joints and members may be found. Finally, beyond allowing for the dimensional interaction between joints and members to be studied, the tool constructed in this study is also valuable to practical engineering. The large amount of data that is generated by the tool allows the engineer to explore the different possible configurations in the process of designing joints. By connecting the output of the tool to the Design Explorer interface, the engineer has the opportunity to search through all the individual characteristics or a specific range and examine different possible connections in an efficient manner. One of the main contributions of this research project, therefore, lies in the tool itself.Civil Engineering | Building Engineering - Structural Desig
Growth-inhibition effects of pacifastin-like peptides on a pest insect: The desert locust, Schistocerca gregaria
No full textThe main reason for the varying degrees of success of peptidase inhibitors (PI) as biological insecticides is the existence of a poorly understood mechanism, which allows pest insects to compensate for PI present in their diet. To challenge this highly flexible physiological mechanism and to prolong the inhibitory effect of PI on insect growth, a number of measures were taken into account before and during experiments with a notorious pest insect, the desert locust, Schistocerca gregaria: (i) non-plant PI (pacifastin-related inhibitors) were used to reduce the risk of a specific co-evolutionary adaptation of the pest insect, (ii) based on the main types of digestive enzymes present in the midgut, mixtures of multiple PI with different enzyme specificity were selected, allowing for a maximal inhibition of the proteolytic activity and (iii) digestive peptidase samples were taken during oral administration experiments to study compensatory mechanisms. Contrary to larvae fed on a diet containing plant-derived PI, a significant growth impediment was observed in larvae that were fed a mixture of different pacifastin-like PI. Nevertheless, the growth inhibition effect of this PI mixture attenuated after a few days, Moreover, a comprehensive study of the observed responses after oral administration of PI revealed that S. gregaria larvae can adjust their secreted digestive enzyme activities in two distinct ways depending on the composition/concentration of the PI-mixture.sponsorship: The authors especially thank Joost Van Duppen and Koen Van Dingenen for their technical assistance, Julie Puttemans for assisting with the figures and Roger Jonckers for maintaining the animal culture. The authors gratefully acknowledge the K.U. Leuven Research Foundation (GOA/11/02), the Research Foundation of Flanders (FWO-Flanders) and the Interuniversity Attraction Poles program (Belgian Science Policy Grant P6/14) for financial support. B.B. obtained a postdoctoral research fellowship from the FWO. J.S. and S.Z. were supported by a PhD fellowship from the IWT (Instituut voor de aanmoediging van Innovatie door Wetenschap en Technologie in Vlaanderen). (K.U. Leuven Research Foundation|GOA/11/02, Research Foundation of Flanders (FWO-Flanders), Interuniversity Attraction Poles program|P6/14, FWO, IWT (Instituut voor de aanmoediging van Innovatie door Wetenschap en Technologie in Vlaanderen))status: Publishe
Transcriptional analysis of the adaptive digestive system of the migratory locust in response to plant defensive protease inhibitors
No full textAbstract: Herbivorous insects evolved adaptive mechanisms to compensate for the presence of plant defensive protease inhibitors (PI) in their food. The underlying regulatory mechanisms of these compensatory responses remain largely elusive. In the current study, we investigated the initiation of this adaptive response in the migratory locust, Locusta migratoria, via microarray analysis of gut tissues. Four hours after dietary uptake of PIs, 114 and 150 transcripts were respectively found up- or downregulated. The results suggest a quick trade-off between compensating for potential loss of digestive activity on the one hand, and stress tolerance, defense, and structural integrity of the gut on the other hand. We additionally addressed the role of a group of related upregulated hexamerin-like proteins in the PI-induced response. Simultaneous knockdown of corresponding transcripts by means of RNA interference resulted in a reduced capacity of the locust nymphs to cope with the effects of PI. Moreover, since insect hexamerins have been shown to bind Juvenile Hormone (JH), we also investigated the effect of JH on the proteolytic digestion in L. migratoria. Our results indicate that JH has a stimulatory effect on the expression of three homologous chymotrypsin genes, while knocking down the JH receptor (methoprene tolerant) led to opposite effects
