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Featured researches published by A.J. Koops.


Journal of The American College of Nutrition | 2002

Increased production of nutriments by genetically engineered crops.

Robert Sévenier; Ingrid M. van der Meer; Raoul Bino; A.J. Koops

Plants are the basis of human nutrition and have been selected and improved to assure this purpose. Nowadays, new technologies such as genetic engineering and genomics approaches allow further improvement of plants. We describe here three examples for which these techniques have been employed. We introduced the first enzyme involved in fructan synthesis, the sucrose sucrose fructosyltransferase (isolated from Jerusalem artichoke), into sugar beet. The transgenic sugar beet showed a dramatic change in the nature of the accumulated sugar, 90% of the sucrose being converted into fructan. The use of transgenic sugar beet for the production and isolation of fructans will result in a more efficient plant production system of fructans and should promote their use in human food. The second example shows how the over-expression of the key enzyme of flavonoid biosynthesis could increase anti-oxidant levels in tomato. Introduction of a highly expressed chalcone isomerase led to a seventyfold increase of the amount of quercetin glucoside, which is a strong anti-oxidant in tomato. We were also able to modify the essential amino acid content of potato in order to increase its nutritional value. The introduction of a feedback insensitive bacterial gene involved in biosynthesis of aspartate family amino acids led to a sixfold increase of the lysine content. Because the use of a bacterial gene could appear to be controversial, we also introduced a mutated form of the plant key enzyme of lysine biosynthesis (dihydrodipicolinate synthase) in potato. This modification led to a 15 times increase of the lysine content of potato. This increase of the essential amino acid lysine influences the nutritional value of potato, which normally has low levels of several essential amino acids. These three examples show how the metabolism of primary constituents of the plant cell such as sugar or amino acids, but also of secondary metabolites such as flavonoids, can be modified by genetic engineering. Producing fructan, a soluble fiber, increasing the level of flavonoids, an antioxidant, in tomato or increasing the level of essential amino acids in potato are all clear examples of plant genetic modifications with possible positive effects on human nutrition.


Journal of Plant Physiology | 2012

Sink filling, inulin metabolizing enzymes and carbohydrate status in field grown chicory (Cichorium intybus L.)

Jeroen van Arkel; Rudy Vergauwen; Robert Sévenier; Johanna C. Hakkert; André Van Laere; Harro J. Bouwmeester; A.J. Koops; Ingrid M. van der Meer

Inulin is a fructose-based polymer that is isolated from chicory (Cichorium intybus L.) taproots. The degree of polymerization (DP) determines its application and hence the value of the crop. The DP is highly dependent on the field conditions and harvest time. Therefore, the present study was carried out with the objective to understand the regulation of inulin metabolism and the process that determines the chain length and inulin yield throughout the whole growing season. Metabolic aspects of inulin production and degradation in chicory were monitored in the field and under controlled conditions. The following characteristics were determined in taproots: concentrations of glucose, fructose and sucrose, the inulin mean polymer length (mDP), yield, gene expression and activity of enzymes involved in inulin metabolism. Inulin synthesis, catalyzed by sucrose:sucrose 1-fructosyltransferase (EC 2.4.1.99) (1-SST) and fructan:fructan 1-fructosyltransferase (EC 2.4.1.100) (1-FFT), started at the onset of taproot development. Inulin yield as a function of time followed a sigmoid curve reaching a maximum in November. Inulin reached a maximum mDP of about 15 in September, than gradually decreased. Based on the changes observed in the pattern of inulin accumulation, we defined three different phases in the growing season and analyzed product formation, enzyme activity and gene expression in these defined periods. The results were validated by performing experiments under controlled conditions in climate rooms. Our results show that the decrease in 1-SST that starts in June is not regulated by day length and temperature. From mid-September onwards, the mean degree of polymerization (mDP) decreased gradually although inulin yield still increased. The decrease in mDP combined with increased yield results from fructan exohydrolase activity, induced by low temperature, and the back transfer activity of 1-FFT. Overall, this study provides background information on how to improve inulin yield and quality in chicory.


Carbohydrate Polymers | 2013

Tailor-made fructan synthesis in plants: a review.

Jeroen van Arkel; Robert Sévenier; Johanna C. Hakkert; Harro J. Bouwmeester; A.J. Koops; Ingrid M. van der Meer

Fructan, a fructose polymer, is produced by many bacteria and plants. Fructan is used as carbohydrate reserve, and in bacteria also as protective outside layer. Chicory is a commercial fructan producing crop. The disadvantage of this crop is its fructan breakdown before harvest. Studies using genetically modification showed that fructan biosynthesis is difficult to steer in chicory. Alternatives for production of tailor-made fructan, fructan with a desired polymer length and linkage type, are originally non-fructan-accumulating plants expressing introduced fructosyltransferase genes. The usage of bacterial fructosyltransferases hindered plant performance, whereas plant-derived fructan genes can successfully be used for this purpose. The polymer length distribution and the yield are dependent on the origin of the fructan genes and the availability of sucrose in the host. Limitations seen in chicory for the production of tailor-made fructan are lacking in putative new platform crops like sugar beet and sugarcane and rice.


Archive | 2017

New Skills for Entrepreneurial Researchers

Mirjam Leloux; Florentin Popescu; A.J. Koops

Knowledge exchange between universities and business in collaborative/contractual research and public-private partnerships has become far more significant. These developments instigate new mind-sets and skills for academic researchers, that should be able to translate their new technological concepts into new (business) developments. Using the two entrepreneurial functions—identification and exploitation— Park (Technovation 25: 739–752, 2005); Wright et al. (J. Technol. Transfer 29: 235–246, 2004) as well as the Vitae Researcher Development Framework (www.vitae.ac.uk) and Entrepreneurial competency framework (Int. J. Entrepreneur. Behav. Res. 6(2): 92–111, 2010), this chapter looks at the new, entrepreneurial skills that any academic researcher needs to make commercial exploitation of research a success. The purpose of this article is to investigate which (i.e. entrepreneurial) skills academic researchers need to facilitate to be more effective in exploiting their research. We especially focus on the academic researcher with a beta-scientific background.


Nature Biotechnology | 1998

High level fructan accumulation in a transgenic sugar beet

Robert Sévenier; Robert D. Hall; I.M. van der Meer; Johanna C. Hakkert; A.J. van Tunen; A.J. Koops


Plant Journal | 1998

Cloning of the fructan biosynthesis pathway of Jerusalem artichoke

Ingrid M. van der Meer; A.J. Koops; Johanna C. Hakkert; Arjen J. van Tunen


Microbial Cell Factories | 2014

Expression of the Aspergillus terreus itaconic acid biosynthesis cluster in Aspergillus niger

Laura van der Straat; Marloes Vernooij; Marieke Lammers; Willy A. M. van den Berg; Tom Schonewille; Jan Cordewener; Ingrid M. van der Meer; A.J. Koops; Leo H. de Graaff


Plant Science | 2008

Differential expression of genes involved in C1 metabolism and lignin biosynthesis in wooden core and bast tissues of fibre hemp (Cannabis sativa L.).

Hetty C. van den Broeck; Chris Maliepaard; Michel J.M. Ebskamp; M.A.J. Toonen; A.J. Koops


Plant Science | 2007

Developmental modulation of inulin accumulation in storage organs of transgenic maize and transgenic potato

Johan Stoop; Jeroen van Arkel; Johanna C. Hakkert; Cheryl Tyree; Perry G. Caimi; A.J. Koops


Archive | 2009

NUCLEOTIDE SEQUENCES CODING FOR CIS-ACONITIC DECARBOXYLASE AND USE THEREOF

A.J. Koops; Leendert Hendrik De Graaff; Ingrid M. van der Meer; Wilhelmus Antonius Maria Van Den Berg

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Robert Sévenier

Wageningen University and Research Centre

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Johanna C. Hakkert

Wageningen University and Research Centre

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Ingrid M. van der Meer

Wageningen University and Research Centre

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Harro J. Bouwmeester

Wageningen University and Research Centre

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Jeroen van Arkel

Wageningen University and Research Centre

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A.J.M. Jansman

Wageningen University and Research Centre

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Elisabeth Hm Temme

Wageningen University and Research Centre

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Florentin Popescu

HAN University of Applied Sciences

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