118,413 research outputs found
Characterisation of sugar beet (<it>Beta vulgaris </it>L. ssp. vulgaris) varieties using microsatellite markers
No full textAbstract Background Sugar beet is an obligate outcrossing species. Varieties consist of mixtures of plants from various parental combinations. As the number of informative morphological characteristics is limited, this leads to some problems in variety registration research. Results We have developed 25 new microsatellite markers for sugar beet. A selection of 12 markers with high quality patterns was used to characterise 40 diploid and triploid varieties. For each variety 30 individual plants were genotyped. The markers amplified 3-21 different alleles. Varieties had up to 7 different alleles at one marker locus. All varieties could be distinguished. For the diploid varieties, the expected heterozygosity ranged from 0.458 to 0.744. The average inbreeding coefficient Fis was 0.282 ± 0.124, but it varied widely among marker loci, from Fis = +0.876 (heterozygote deficiency) to Fis = -0.350 (excess of heterozygotes). The genetic differentiation among diploid varieties was relatively constant among markers (Fst = 0.232 ± 0.027). Among triploid varieties the genetic differentiation was much lower (Fst = 0.100 ± 0.010). The overall genetic differentiation between diploid and triploid varieties was Fst = 0.133 across all loci. Part of this differentiation may coincide with the differentiation among breeders' gene pools, which was Fst = 0.063. Conclusions Based on a combination of scores for individual plants all varieties can be distinguished using the 12 markers developed here. The markers may also be used for mapping and in molecular breeding. In addition, they may be employed in studying gene flow from crop to wild populations.</p
On one's own feet - Falls, risk factors and falls prevention in persons with intellectual disabilities.
No full textContains fulltext :
125602.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 16 april 2014Promotores : Geurts, A.C.H., Schrojenstein Lantman, H.M.J. van Co-promotores : Weerdesteyn, V.G.M., Smulders, C.J.M.209 p
Trade Pessimists vs Technology Optimists: Induced Technical Change and Pollution Havens
No full textOur paper focuses on the role of endogenous technology and technology spillovers in explaining cross country differences in pollution and the pollution haven effect of international trade. In our North-South trade model, technology is endogenously developed by the North and imitated by the South. Environmental regulators choose national environmental policies by trading off the income gains and the disutility from a rise in pollution. Differences in environmental stringency are entirely driven by differences in investment opportunities and distortions that follow from the difference in intellectual property rights protection. We show that without goods trade and in the absence of technology subsidies, the North imposes more stringent environmental regulation than the South. When opening up to trade, the South experiences a rise in prices for pollution-intensive goods and tends to raise pollution as in a standard trade model. Induced technical change, however, may reverse this pollution haven effect
A genetic analysis of the introgression process from cultivated lettuce (Lactuca sativa L.) to wild prickly lettuce (L. serriola L.)
No full text Many plant species can hybridise and produce fertile offspring. Hybridization between cultivated species and their wild relatives has raised concerns with regard to GM crops, as it constitutes a possible route along which the transgene could disperse from crops into related wild species, establish itself in the natural population, and persist under natural conditions. This may cause unintended ecological consequences such as the formation of more invasive weeds and genetic erosion. After crop-wild hybridization, the persistence of the hybrids and of the crop genes (including the transgenes) in later generations depends on their genetic make-up, which consists of specific combinations of wild and crop genomic segments, and on the environmental conditions. Therefore, knowledge on the dynamics of crop-wild hybridization and introgression using conventional crop varieties is needed as it constitutes the baseline for putting into perspective the effects of transgene introgression under natural conditions. This study focused on understanding the genetic process of hybridization and introgression from cultivated to wild relative species using cultivated lettuce (Lactuca sativa L.) and its closest wild relative, prickly lettuce (L. serriola L.) as a crop-wild complex model. Natural populations of prickly lettuce in Europe were tested for the occurrence of crop-wild hybrids using Bayesian-based programmes (Structure, InStruct and NewHybrids) which returned a crop-wild hybrid occurrence of 7%. However, the geographical location of the hybrids led to the conclusion that crop-wild hybridization is not the cause of the recent northward spread of L. serriola in Europe. To test for the importance of the crop genomic segments to the performance of lettuce crop-wild hybrids, three hybrid generations were created (F2 as a selfing generation, and BC1 and BC2, backcrossed to the wild genotype to mimick the introgression process) by crossing L. sativa (cv. Dynamite) with L. serriola collected from Eys (the Netherlands). The three populations were genotyped with Single Nucleotide Polymorphism markers for genetic analysis. Because of the importance of the abiotic stresses as selection factors under natural conditions and the prospective of generating GM crop varieties with enhanced abiotic stress tolerance, the three populations were evaluated for vigour at the rosette stage under greenhouse conditions of non-stress, drought, salinity and nutrient deficiency. The BC1 population was also evaluated under field conditions at two locations (Wageningen and Sijbekarspel, the Netherlands) for hybrid germination, vigour, survival and reproduction. Based on the location and allelic effect of the QTLs for germination, vigour, survival and reproductive traits in the current lettuce crop-wild cross, genomic regions were suggested where transgenes could be or could not be located in order to mitigate their persistence in crop-wild hybrids through genetic hitchhiking and background selection. </p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
De Erfenis.
No full textResearch, scenario en advies: Moniek Hover, Jeroen Vandeneijnde, Andreas Smulders
De Erfenis.
No full textResearch, scenario en advies: Moniek Hover, Jeroen Vandeneijnde, Andreas Smulders
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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