Photomorphogenetic mutants of higher plants

In this thesis the hypothesis that different molecular types of phytochrome have different physiological roles has been elaborated and an attempt has been made to assign functions to these phytochrome types. For this purpose a genetic approach was chosen and the following potential phytochrome mutants were used: the tomato aurea ( au ) mutant; the cucumber long-hypocotyl ( lh ) mutant and the Arabidopsis long-hypocotyl ( hy3 ) mutant. Comparing the response of the mutant affected in the abundance or function of a particular phytochrome type with that of its isogenic wild type shows directly the relevance of the phytochrome type concerned. The au mutant is proposed to lack the light-labile phytochrome type (phy A), while normal levels of the lightstable phytochrome type (phy B) are present. This results in a reduction of. (i) the inhibition of the hypocotyl growth; (ii) the anthocyanin synthesis; (iii) the chlorophyll content, but a normal end-of-day far-red (EOD FR) response. In the lh and hy3 mutants the opposite situation appears to be found: normal levels of phy A, but a lack of phy B. Both the lh and hy3 mutant do not show the EOD FR response, while the hypocotyl growth in continuous R and B is less inhibited when compared to the wild type. Therefore it is proposed that phy B plays a role in the EOD FR response, while both phy A and phy B are important for the inhibition of the hypocotyl growth. With the help of other mutants described in the literature a more detailed assignment of functions to the different phytochrome types is proposed.In addition, a potential phytochrome signal transduction mutant, the tomato high- pigment ( hp ) mutant, was characterized. This mutant exhibits exaggerated phytochrome responses, e.g. high anthocyanin synthesis and short hypocotyl length when compared to wild type. It. is proposed that the hp mutation affects an amplification step in the phytochrome transduction chain

Vitamin D Pathway Gene Variants and Prostate Cancer Risk

Vitamin D has antiproliferative, antiangiogenic, and apoptotic properties. There is some evidence supporting an association between vitamin D-related gene variants and prostate cancer risk. We report results from this population-based case-control study of genes encoding for the vitamin D receptor (VDR), the vitamin D activating enzyme 1-alpha-hydroxylase (CYP27B1), and deactivating enzyme 24-hydroxylase (CYP24A1). Forty-eight tagging single nucleotide polymorphisms (tagSNP) were analyzed in 827 incident prostate cancer cases diagnosed from 2002 to 2005, and in 787 age-matched controls. Contrary to some earlier studies, we found no strong evidence of altered risk of developing prostate cancer overall or within clinical measures of tumor aggressiveness for any of the tagSNPs when they were assessed individually or in haplotypes

Using microsatellites to obtain genetic structure data for Red-backed shrike (Lanius collurio) : a pilot study

Contains fulltext : 33090.pdf (publisher's version ) (Open Access

The JWS online simulation database

Summary: JWS Online is a web-based platform for construction, simulation and exchange of models in standard formats. We have extended the platform with a database for curated simulation experiments that can be accessed directly via a URL, allowing one-click reproduction of published results. Users can modify the simulation experiments and export them in standard formats. The Simulation database thus lowers the bar on exploring computational models, helps users create valid simulation descriptions and improves the reproducibility of published simulation experiments. Availability and Implementation: The Simulation Database is available on line at https://jjj.bio.vu. nl/models/experiments/

COVID-19 and Cancer: Current Challenges and Perspectives.

Patients with cancer have been disproportionately affected by the COVID-19 pandemic. This effect has included the adverse outcomes in patients with cancer who develop COVID-19, the impact of the COVID-19 pandemic on the delivery of cancer care, and the severe disruption to cancer research. However, patients with cancer are a heterogeneous population, and recent studies have now documented factors that allow risk stratification of patients with cancer in order to optimize care. In this review, we highlight data at the intersection of COVID-19 and cancer, including the biological interplay between the two diseases and practical recommendations for the treatment of patients with cancer during the pandemic. We additionally discuss the potential long-lasting impact of the pandemic on cancer care due to its deleterious effect on cancer research, as well as biological insights from the cancer research community that could help develop novel therapies for all patients with COVID-19

Observed photodetachment in parallel electric and magnetic fields

We investigate photodetachment from negative ions in a homogeneous 1.0-T magnetic field and a parallel electric field of approximately 10 V/cm. A theoretical model for detachment in combined fields is presented. Calculations show that a field of 10 V/cm or more should considerably diminish the Landau structure in the detachment cross section. The ions are produced and stored in a Penning ion trap and illuminated by a single-mode dye laser. We present preliminary results for detachment from S- showing qualitative agreement with the model. Future directions of the work are also discussed.Comment: Nine pages, five figures, minor revisions showing final publicatio

Constrained Willmore Surfaces

Constrained Willmore surfaces are conformal immersions of Riemann surfaces that are critical points of the Willmore energy $W=\int H^2$ under compactly supported infinitesimal conformal variations. Examples include all constant mean curvature surfaces in space forms. In this paper we investigate more generally the critical points of arbitrary geometric functionals on the space of immersions under the constraint that the admissible variations infinitesimally preserve the conformal structure. Besides constrained Willmore surfaces we discuss in some detail examples of constrained minimal and volume critical surfaces, the critical points of the area and enclosed volume functional under the conformal constraint.Comment: 17 pages, 8 figures; v2: Hopf tori added as an example, minor changes in presentation, numbering changed; v3: new abstract and appendix, several changes in presentatio