In this thesis, patterns of variation in plant metabolomes and insect communities were described in GM and non-GM potato plants in both laboratory and field experiments. Differences between plant... Show moreIn this thesis, patterns of variation in plant metabolomes and insect communities were described in GM and non-GM potato plants in both laboratory and field experiments. Differences between plant genotypes in insect abundances were small when compared to year-to-year differences, location effects and differences between developmental stages of plants. Standardized effect sizes are discussed as an alternative scale for measuring effects. Leaf age, aphid infestation and virus infection were found to cause significant alterations in leaf metabolism in a laboratory study as measured by 1H NMR. However, these changes were similar in quantity and quality in both GM and non-GM plants. Furthermore, 1H NMR metabolomic profiles of potato plants were measured in a 2-year field study. Large changes in metabolomic profiles occurred across years and locations, and throughout the growth period of plants within years. Only weak relationships were found between metabolomics data and insect abundances on the same experimental fields. GxE interactions imply that conclusions from field trials are not valid outside the range of tested environments. This emphasizes the need for a careful choice of representative geographical zones for risk assessment studies. However, it also shows that a residual level of uncertainty in NTO safety is unavoidable. Show less
Agrobacterium tumefaciens is a phytopathogen which is known to be the causal agent of crown gall disease in dicotyledonous plants. Virulent Agrobacterium strains are always carrier of a tumor... Show moreAgrobacterium tumefaciens is a phytopathogen which is known to be the causal agent of crown gall disease in dicotyledonous plants. Virulent Agrobacterium strains are always carrier of a tumor-inducing (Ti) plasmid. As a result of the expression of Vir proteins, a section of this plasmid termed the T-DNA is transferred via a type four secretion system (T4SS) as a T-strand to the recipient cell where it can integrate into the genomic DNA of the recipient cell. In this thesis the prerequisites of T-DNA circle formation using yeast as a model were assayed. It was found that the homologous repair (HR) protein Rad52 is of importance to the formation of T-DNA circles. In addition to this, the effects of double strand break (DSB) induction on the efficiency of T-DNA integration via the HR pathway in yeast and the role the nucleosome occupancy of the target locus has on DSB induction were assayed. It was found that a decrease in the nucleosome occupancy of a target locus had no measurable impact on the efficiency of T-DNA integration at this locus. However, the combined translocation of nuclease proteins aimed at the target locus and T-strands during AMT greatly facilitated HR-mediated integration of T-DNA. Show less
The (seco)iridoids and their derivatives, the monoterpenoid indole alkaloids (MIAs), form two large families of plant-derived bioactive compounds with a wide spectrum of high-value pharmacological... Show moreThe (seco)iridoids and their derivatives, the monoterpenoid indole alkaloids (MIAs), form two large families of plant-derived bioactive compounds with a wide spectrum of high-value pharmacological and insect-repellent activities. Vinblastine and vincristine, MIAs used as anti-cancer drugs, are produced by Catharanthus roseus in extremely low levels, leading to high market prices and poor availability. Their biotechnological production is hampered by the fragmentary knowledge of their biosynthesis. Here we report the discovery of the last four missing steps of the (seco)iridoid biosynthesis pathway. Expression of the eight genes encoding this pathway together with two genes boosting precursor formation and two downstream alkaloid biosynthesis genes in an alternative plant host allowed the heterologous production of the complex MIA strictosidine. This confirms the functionality of all enzymes of the pathway and highlights their utility for synthetic biology programs towards a sustainable biotechnological production of valuable (seco)iridoids and alkaloids with pharmaceutical and agricultural applications. Show less
Natural deep eutectic solvents (NADES) ionic liquids (ILs) and deep eutectic solvents (DES) were proposed by our group to extend the range of ILs and DES, particularly to develop cheap, nontoxic,... Show moreNatural deep eutectic solvents (NADES) ionic liquids (ILs) and deep eutectic solvents (DES) were proposed by our group to extend the range of ILs and DES, particularly to develop cheap, nontoxic, and low viscosity green solvents, and to apply them in health-related fields. They are liquid supramolecules composed of common metabolites in certain molar ratios, including some water in some cases, which are characterized by extensive intermolecular interactions e.g. hydrogen bonds and ionic bonds. NADES present many advantages including low cost, simple preparation, low or negligible toxicity profile and sustainability in view of environment and economics benefits. Their preparation methods, physicochemical properties, supramolecules structures are reported in this thesis. For application, compare to conventional solvents, they show higher solubilization and extraction ability, especially for non-water soluble compounds. They are stable liquids even below zero oC, and their physicochemical properties can be adjusted by changing the water content. In the presence of NADES, anthocyanins and phenolic compounds such as carthamin show higher stability. In addition, we hypothesize that NADES might be involved in the biosynthesis, storage, and transport of various non-water soluble metabolites in cells. In-vitro evidences for their possible functions are also explored in this thesis. Show less
Agrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium... Show moreAgrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium can also transform many different non-plant organisms such as the yeast Saccharomyces cerevisiae. During this process, a number of virulence proteins, including VirF and VirE3, are translocated into the host cell. VirF contains an F-box domain and, according to current theory, in plants and in yeast may induce degradation of the virulence protein VirE2 and the transcription factor VIP1, required for the integration of the T-DNA into host chromosomal DNA. VirE3 functions as a potential plant transcriptional activator. In our study, we expressed the Agrobacterium virulence proteins VirF and VirE3 in Saccharomyces cerevisiae and Arabidopsis thaliana and studied the effect of virF and virE3 expression on the genome-wide transcription in S. cerevisiae and A.thaliana using DNA microarrays and RNA-sequencing. Show less
Freshwater eels (Anguilla spp.) intrigued scientists for centuries. Their life cycle involves for example two distinct larval stages and a long distance migration, which may cover thousands of... Show moreFreshwater eels (Anguilla spp.) intrigued scientists for centuries. Their life cycle involves for example two distinct larval stages and a long distance migration, which may cover thousands of kilometers. The farming of eels is still dependent on the influx of wild glass eels, because eels do not mature naturally in captivity due to strong neural inhibition. Since the 1980s, the glass eel influx of several eel species drastically declined. The European eel (A. anguilla) was recently enlisted by the IUCN as a critically endangered species; therefore there is an urgent call for eel management and artificial reproduction. Artificial reproduction may contribute to restoration of the eel population by releasing the current fishing pressures on the wild stocks, and allowing a sustainable eel aquaculture in the future. Although, artificial reproduction by applying hormone treatments is possible to some extent, success ra tes are still far from creating a sustainable aquaculture. This thesis focuses on the spawning migration, maturation and reproduction of eels. New tools are developed that may improve current artificial maturation and reproduction protocols for eel aquaculture. Show less
This thesis provides a comparison of mostly perceptual development during vocal learning in songbirds (zebra finches) and human infants. The aim is to disentangle experience dependent and... Show moreThis thesis provides a comparison of mostly perceptual development during vocal learning in songbirds (zebra finches) and human infants. The aim is to disentangle experience dependent and independent processes during vocal learning. In both human infants and juvenile songbirds, a perceptual preference for __universal__ sounds was found, independent of adult auditory input. Later in development, both infants and juvenile songbirds show a change is preference. The juvenile songbirds clearly change their preference towards sounds they have been auditorily exposed to (chapter 3). In human infants in the influence of experience is less clear in this thesis. In combination with previous literature the most likely scenario is a combination of experience dependent and independent processes (chapter 2). To further compare human and birdsong phonology, a __typology__ of zebra finch song elements was performed (chapter 4). The results of this study indicate commonality as well as variation between populations in terms of phonology. In the order of elements within a sequence however, there is little evidence for common patterns across populations and there is variation within and between populations. In summary, this thesis shows similarities in developmental mechanisms in two vocally learning species. There might be a link between development and typology. Show less
Inflammation is an immune reaction of the body to the external stimuli such as toxins or pathogens, and is characterized by redness, swelling, pain, and heat. The process of inflammation is... Show moreInflammation is an immune reaction of the body to the external stimuli such as toxins or pathogens, and is characterized by redness, swelling, pain, and heat. The process of inflammation is regulated by several pro-inflammatory and antiinflammatory cytokines. Tumor necrosis factor-_ (TNF-_) is a major pro-inflammatory cytokine involved in the inflammatory response.Elevated TNF-_ expression has been found to be associated with the development of diabetes, atherosclerosis, septic shock, and tumorigenesis. Thus inhibition of TNF-_ at any step of inflammatory pathways provides an attractive treatment for inflammatory diseases as well as for series of other common diseases.Plants provide an alternative sources of medicines used traditionally by people worldwide since thousands of years ago. The aim of this thesis was to develop methods for the rapid identification of active compounds in plant extracts by correlating NMR metabolomics and bioassay results by means of multivariate data analysis. This work demonstrates the great potential of NMR spectroscopy in combination with chemometrics for the screening of large set of crude extracts, to study the effects of different variables on the activity, and identifying sets of active compounds in complex mixtures like plant extracts. Show less
A scientific correlational study on human resource and organisational policy-oriented study, which was conducted in the Mara Region of Tanzania. It specifically investigates major factors,... Show moreA scientific correlational study on human resource and organisational policy-oriented study, which was conducted in the Mara Region of Tanzania. It specifically investigates major factors, which correlate to interprofessional collaborative behaviours in the context of health service delivery between traditional and modern medical practitioners. Interprofessional collaboration is a sine qua non stage towards fully integrated health care encapsulated in a coined Swahili concept of afya jumuishi. The sample population in this study includes medical practitioners from both Modern Medicine (MM) and Traditional Medicine (TM) systems in the Mara Region. The operationalisation of the concept of interprofessional collaboration as used in the analytical model of this study follows the definition by the ‘Centre for Advancement of Collaborative Strategies in Health’ (2003), which defines it as behavioural patterns as part of synergy formation among different professionals. Such behavioural patterns have two interrelated components of dependent factors which include: the behavioural patterns of sharing resources; and - the behavioural patterns of working jointly for clients. The analytical model used is based on Slikkerveer (1990) which is built up on seven blocks of variables. These variables are independent variables, which include socio-demographic, psycho-social, enabling, trustworthiness, organisational and intervening variables as well as the dependent variables which include collaborative behavioural patterns of exchange of resources and collaborative behavioural patterns of working jointly for clients and patients. The general major challenges of the Twenty-First Century facing Traditional Medicine (TM) in the country include: - Lack of enabling environment towards Traditional Medicine (TM); - Absence of a mechanism, which promotes integration between modern and Traditional Medicine (TM); - Weak protection of indigenous intellectual property rights and unsustainable harvesting of medicinal plants; - Dwindling of natural resources; - Lack of indigenous information system and reliable data bank; - The need to carry out education, research and development on Traditional Medicine (TM); - The problem of safety of products of Traditional Medicine (TM); contextualization of the world’s eligions on teachings about Traditional Medicine (TM); - Moral degradation and the breaking of social structures;- Shocking poverty in the society. Show less
This thesis is concerns research on monoterpenoids, sesquiterpenoids, and diterpenoids with medicinal properties. Terpenoids from commond herbs as well as Cannabis sativa, Inula britannica,... Show moreThis thesis is concerns research on monoterpenoids, sesquiterpenoids, and diterpenoids with medicinal properties. Terpenoids from commond herbs as well as Cannabis sativa, Inula britannica, Tanacetum parthenium, and Salvia officinalis were investigated Show less
