Transverse sectioning of Arabidopsis thaliana leaves using resin embedding

The leaf is the major functional part of the shoot performing the bulk of photosynthetic activity. Its development is relatively plastic allowing the plant to adapt to environmental changes by modifying leaf size and anatomy. Moreover, a leaf is made up of various distinct cell layers, each having specialized functions. To understand functional adaptation and the development of the leaf it is essential to obtain cross sections throughout leaf development and at maturity (Kalve et al., 2014). Here, we describe a protocol for transverse sectioning of Arabidopsis thaliana leaves using resin embedding. This protocol provides a reliable platform to yield high quality images of cross sections allowing study of development of various tissue layers across the transversal axis of the leaf. As this method is an adaptation of the protocol developed for the Arabidopsis root tip by Beeckman and Viane (1999) and De Smet et al. (2004), it can easily be modified to accommodate other organs and species

Quality improvement of vocational rehabilitation in patients with chronic musculoskeletal pain and reduced work participation

Research has shown that multi-domain vocational rehabilitation (VR) is beneficial in achieving sustainable levels of work participation in sick-listed workers with chronic musculoskeletal pain (CMP). There are however some research gaps regarding “clinimetrics” and “dose-content” of VR. Some of these parts are studied in this thesis, with the aim to contribute to the quality improvement of VR for patients with chronic musculoskeletal pain and reduced work participation.The most important findings of the thesis are:- The development of a core set consisting of diagnostic and evaluative questionnaires. The core set was implemented in 2014 and since then used by seven Dutch VR centers.- Insights into the clinimetric properties of relevant questionnaires on the constructs of “work participation”, “healthcare usage”, and “pain-related disability.” This provided information detailing which questionnaires, and/or cut-off scores can be used for diagnostic, process-related, and evaluative purposes in VR.- Experiences from patients, professionals, and managers with comprehensive and less-comprehensive VR were collected. The overall conclusion is that it is not useful to deliver one VR program for all patients and that treatment should be personalized through the use of quasi-flexible and tailored VR. - The relationship between multicomponent VR both with and without an additional work module on work participation showed to be non-significant. It should therefore be recommended to not include a work module to VR as part of standardized care, but the decision to include or not should be determined on a patient by patient basis

WTAQ and the Green Bay Countree

A brochure that highlights the regions served by WTAQ. Each region has its own detailed section that includes history on its beginning. Throughout the brochure there are pictures and names of the WTAQ staff

The plant-specific cyclin-dependent kinase CDKB1;1 and transcription factor E2Fa-DPa control the balance of mitotically dividing and endoreduplicating cells in Arabidopsis

Transgenic Arabidopsis thaliana plants overproducing the E2Fa-DPa transcription factor have two distinct cell-specific phenotypes: some cells divide ectopically and others are stimulated to endocycle. The decision of cells to undergo extra mitotic divisions has been postulated to depend on the presence of a mitosis-inducing factor (MIF). Plants possess a unique class of cyclin-dependent kinases (CDKs; B-type) for which no ortholog is found in other kingdoms. The peak of CDKB1;1 activity around the G2-M boundary suggested that it might be part of the MIF. Plants that overexpressed a dominant negative allele of CDKB1;1 underwent enhanced endoreduplication, demonstrating that CDKB1;1 activity was required to inhibit the endocycle. Moreover, when the mutant CDKB1;1 allele was overexpressed in an E2Fa-DPa–overproducing background, it enhanced the endoreduplication phenotype, whereas the extra mitotic cell divisions normally induced by E2Fa-DPa were repressed. Surprisingly, CDKB1;1 transcription was controlled by the E2F pathway, as shown by its upregulation in E2Fa-DPa–overproducing plants and mutational analysis of the E2F binding site in the CDKB1;1 promoter. These findings illustrate a cross talking mechanism between the G1-S and G2-M transition points

Transport van X-virus in de aardappel (Solanum tuberosum L.) bij primaire infectie

The time needed for potato virus X to reach the tubers from the inoculated leaf depended closely on the age of the potato plant. In young plants the virus could be detected in the tubers after about five days. However in the period of maximum tuber formation, virus translocation occurred only incidentally. The phenomenon of gradually decreased speed of virus translocation was called old-age resistance. It also played a part in infections with aphid-borne viruses such as potato leafroll virus and virus Y. It had practical significance for the production of seed potatoes as it was already noticeable in the period of highest aphid populations. When potato plants were inoculated in an advanced stage of development only part of the vegetative progeny got infected. This meant that a plant produced infected and uninfected tubers, and also that a single tuber had infected as well as uninfected parts. The bigger tubers of a primarily infected plant were more often infected than smaller ones. Moreover, the eyes at the top end of the tuber had a greater chance of attracting infection than those occurring close to the heel end.<p/

The cyclin-dependent kinase inhibitor Orysa;KRP1 plays an important role in seed development of rice

Kip-related proteins (KRPs) play a major role in the regulation of the plant cell cycle. We report the identification of five putative rice (Oryza sativa) proteins that share characteristic motifs with previously described plant KRPs. To investigate the function of KRPs in rice development, we generated transgenic plants overexpressing the Orysa; KRP1 gene. Phenotypic analysis revealed that overexpressed KRP1 reduced cell production during leaf development. The reduced cell production in the leaf meristem was partly compensated by an increased cell size, demonstrating the existence of a compensatory mechanism in monocot species by which growth rate is less reduced than cell production, through cell expansion. Furthermore, Orysa; KRP1 overexpression dramatically reduced seed filling. Sectioning through the overexpressed KRP1 seeds showed that KRP overproduction disturbed the production of endosperm cells. The decrease in the number of fully formed seeds was accompanied by a drop in the endoreduplication of endosperm cells, pointing toward a role of KRP1 in connecting endocycle with endosperm development. Also, spatial and temporal transcript detection in developing seeds suggests that Orysa; KRP1 plays an important role in the exit from the mitotic cell cycle during rice grain formation