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41.
Koopman WJ Wissemann V De Cock K Van Huylenbroeck J De Riek J Sabatino GJ Visser D Vosman B Ritz CM Maes B Werlemark G Nybom H Debener T Linde M Smulders MJ 《American journal of botany》2008,95(3):353-366
The genus Rosa has a complex evolutionary history caused by several factors, often in conjunction: extensive hybridization, recent radiation, incomplete lineage sorting, and multiple events of polyploidy. We examined the applicability of AFLP markers for reconstructing (species) relationships in Rosa, using UPGMA clustering, Wagner parsimony, and Bayesian inference. All trees were well resolved, but many of the deeper branches were weakly supported. The cluster analysis showed that the rose cultivars can be separated into a European and an Oriental cluster, each being related to different wild species. The phylogenetic analyses showed that (1) two of the four subgenera (Hulthemia and Platyrhodon) do not deserve subgeneric status; (2) section Carolinae should be merged with sect. Cinnamomeae; (3) subsection Rubigineae is a monophyletic group within sect. Caninae, making sect. Caninae paraphyletic; and (4) there is little support for the distinction of the five other subsections within sect. Caninae. Comparison of the trees with morphological classifications and with previous molecular studies showed that all methods yielded reliable trees. Bayesian inference proved to be a useful alternative to parsimony analysis of AFLP data. Because of their genome-wide sampling, AFLPs are the markers of choice to reconstruct (species) relationships in evolutionary complex groups. 相似文献
42.
The kinetic effects of the binding of various metal ions (Ca(2+), Cd(2+), Co(2+), Mg(2+), Mn(2+), Sr(2+) and Zn(2+)) to apo bovine alpha-lactalbumin has been monitored by means of stopped-flow fluorescence spectroscopy. Our results show that the measured rate constant for the binding of metal ions to the Ca(2+)-site increases with increasing binding constant. This is, however, not the case for metal ions binding to the Zn(2+)-site. The binding experiments performed at different temperatures allowed us to calculate the activation energy for the transition from the metal-free to the metal-loaded state of the protein. These values do not depend on the nature of the metal ion but are correlated with the type of binding site. As a result, we were able to demonstrate that Mg(2+), a metal ion which was thought to bind to the Ca(2+)-site, shows the same binding characteristics as Co(2+) and Zn(2+) and therefore most likely interacts with the residues belonging to the Zn(2+)-binding site. 相似文献
43.
Katrien Bortier Karine Vandermeiren Ludwig De Temmerman Reinhart Ceulemans 《Trees - Structure and Function》2001,15(2):75-82
Beech seedlings (Fagus sylvatica L.) were exposed to episodes of O3 in environmentally controlled growth chambers during one growing season. Three treatments were applied: charcoal-filtered air, charcoal-filtered air with the addition of 40 ppb O3 for seven episodes of 5 days' duration (9000-1700 hours), and charcoal-filtered air with the addition of 100 ppb O3 for seven episodes of 5 days' duration (9000-1700 hours). The accumulated exposure over a threshold of 40 ppb in the last treatment reached 13,911 ppb h. Throughout the growing season we measured growth as well as photosynthetic properties and related effects to external and calculated internal doses of O3, using stomatal conductance (gs) data. Growth, measured as diameter increment and biomass, was not significantly affected by the O3 treatments. In the 100-ppb treatment, light-saturated CO2 assimilation rates and chlorophyll content were significantly reduced, and the chlorophyll fluorescence parameter Fv/Fm was significantly reduced at times of high uptake rates and coincided with strong reductions of assimilation rates. O3 uptake was lowered in the 100-ppb treatment due to reduced gs. There was serious visible damage by the end of the exposure period in the 100-ppb treatment, while the treatment with 40 ppb O3 did not seem to cause any significant changes. 相似文献
44.
Establishing life is a calcium-dependent TRiP: Transient receptor potential channels in reproduction
Katrien De Clercq Joris Vriens 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2018,1865(11):1815-1829
Calcium plays a key role in many different steps of the reproduction process, from germ cell maturation to placental development. However, the exact function and regulation of calcium throughout subsequent reproductive events remains rather enigmatic. Successful pregnancy requires the establishment of a complex dialogue between the implanting embryo and the endometrium. On the one hand, endometrial cell will undergo massive changes to support an implanting embryo, including stromal cell decidualization. On the other hand, trophoblast cells from the trophectoderm surrounding the inner cell mass will differentiate and acquire new functions such as hormone secretion, invasion and migration. The need for calcium in the different gestational processes implicates the presence of specialized ion channels to regulate calcium homeostasis. The superfamily of transient receptor potential (TRP) channels is a class of calcium permeable ion channels that is involved in the transformation of extracellular stimuli into the influx of calcium, inducing and coordinating underlying signaling pathways. Although the necessity of calcium throughout reproduction cannot be negated, the expression and functionality of TRP channels throughout gestation remains elusive. This review provides an overview of the current evidence regarding the expression and function of TRP channels in reproduction. 相似文献
45.
Michael Dumbacher Tom Van Dooren Katrien Princen Koen De Witte Mélissa Farinelli Sam Lievens Jan Tavernier Wim Dehaen Stefaan Wera Joris Winderickx Sara Allasia Amuri Kilonda Stéphane Spieser Arnaud Marchand Patrick Chaltin Casper C. Hoogenraad Gerard Griffioen 《Molecular neurodegeneration》2018,13(1):50
Background
Neuronal Ca2+ dyshomeostasis and hyperactivity play a central role in Alzheimer’s disease pathology and progression. Amyloid-beta together with non-genetic risk-factors of Alzheimer’s disease contributes to increased Ca2+ influx and aberrant neuronal activity, which accelerates neurodegeneration in a feed-forward fashion. As such, identifying new targets and drugs to modulate excessive Ca2+ signalling and neuronal hyperactivity, without overly suppressing them, has promising therapeutic potential.Methods
Here we show, using biochemical, electrophysiological, imaging, and behavioural tools, that pharmacological modulation of Rap1 signalling by inhibiting its interaction with Pde6δ normalises disease associated Ca2+ aberrations and neuronal activity, conferring neuroprotection in models of Alzheimer’s disease.Results
The newly identified inhibitors of the Rap1-Pde6δ interaction counteract AD phenotypes, by reconfiguring Rap1 signalling underlying synaptic efficacy, Ca2+ influx, and neuronal repolarisation, without adverse effects in-cellulo or in-vivo. Thus, modulation of Rap1 by Pde6δ accommodates key mechanisms underlying neuronal activity, and therefore represents a promising new drug target for early or late intervention in neurodegenerative disorders.Conclusion
Targeting the Pde6δ-Rap1 interaction has promising therapeutic potential for disorders characterised by neuronal hyperactivity, such as Alzheimer’s disease.46.
Allometric equations for yield predictions of enset (Ensete ventricosum) and khat (Catha edulis) grown in home gardens of southern Ethiopia
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B.T. Mellisse K. Descheemaeker M.J. Mourik G.W.J. van de Ven 《The Annals of applied biology》2017,171(1):95-102
Enset is a large, single‐stemmed perennial herbaceous plant domesticated as a staple food crop only in Ethiopia. Khat is a perennial plant cultivated for its economically important leaves and twigs that are the sources of stimulant when chewed. We address the issue of yield estimation of both crops, as they are important for the livelihoods of smallholders in the home garden systems in Southern Ethiopia and have received little attention so far. The objective of this study was to develop linear allometric models for estimating the edible (food and feed) and commercial yields of enset and khat plants, respectively. Data were collected from 20 enset and 100 khat plants. Diameter at 50‐cm height (d50), pseudostem height (hp) and their combination were good predictor variables for the food products of enset with adjusted R2 values above 0.85, while d50, hp, edible pseudostem height (hep), total height (ht) and their combination were good predictor variables for the feed products of enset with adjusted R2 values above 0.70. For dwarf khat plants crown area (ca) combined with total height (ht) resulted in the best prediction with an adjusted R2 of 0.77, while the leaf and twig dry weight for tall khat plants was best predicted by ca with adjusted R2 of 0.43. In all cases linear models were used. 相似文献
47.
Mátrai J Lammens W Jonckheer A Le Roy K Rabijns A Van den Ende W De Maeyer M 《Proteins》2008,71(2):552-564
In the present study, we report on the X-ray crystallographic structure of a GH32 invertase mutant, (i.e., the Arabidopsis thaliana cell-wall invertase 1-E203Q, AtcwINV1-mutant) in complex with sucrose. This structure was solved to reveal the features of sugar binding in the catalytic pocket. However, as demonstrated by the X-ray structure the sugar binding and the catalytic pocket arrangement is significantly altered as compared with what was expected based on previous X-ray structures on GH-J clan enzymes. We performed a series of docking and molecular dynamics simulations on various derivatives of AtcwINV1 to reveal the reasons behind this modified sugar binding. Our results demonstrate that the E203Q mutation introduced into the catalytic pocket triggers conformational changes that alter the wild type substrate binding. In addition, this study also reveals the putative productive sucrose binding modus in the wild type enzyme. 相似文献
48.
Katrien Janssens Line De Kimpe Michele Balsamo Sandy Vandoninck Jackie R. Vandenheede Frank Gertler Johan Van Lint 《Cellular signalling》2009,21(2):282-292
EVL-I is a splice variant of EVL (Ena/VASP like protein), whose in vivo function and regulation are still poorly understood. We found that Protein Kinase D (PKD) interacts in vitro and in vivo with EVL-I and phosphorylates EVL-I in a 21 amino acid alternately-included insert in the EVH2 domain. Following knockdown of the capping protein CPβ and spreading on laminin, phosphorylated EVL-I can support filopodia formation and the phosphorylated EVL-I is localized at filopodial tips. Furthermore, we found that the lamellipodial localization of EVL-I is unaffected by phosphorylation, but that impairment of EVL-I phosphorylation is associated with ruffling of lamellipodia upon PDBu stimulation. Besides the lamellipodial and filopodial localization of phosphorylated EVL-I in fibroblasts, we determined that EVL-I is hyperphosphorylated and localized in the cell–cell contacts of certain breast cancer cells and mouse embryo keratinocytes. Taken together, our results show that phosphorylated EVL-I is present in lamellipodia, filopodia and cell–cell contacts and suggest the existence of signaling pathways that may affect EVL-I via phosphorylation of its EVH2 domain. 相似文献
49.
50.
Bentahir M Nyabi O Verhamme J Tolia A Horré K Wiltfang J Esselmann H De Strooper B 《Journal of neurochemistry》2006,96(3):732-742
Mutations in human presenilin (PS) genes cause aggressive forms of familial Alzheimer's disease. Presenilins are polytopic proteins that harbour the catalytic site of the gamma-secretase complex and cleave many type I transmembrane proteins including beta-amyloid precursor protein (APP), Notch and syndecan 3. Contradictory results have been published concerning whether PS mutations cause 'abnormal' gain or (partial) loss of function of gamma-secretase. To avoid the possibility that wild-type PS confounds the interpretation of the results, we used presenilin-deficient cells to analyse the effects of different clinical mutations on APP, Notch, syndecan 3 and N-cadherin substrate processing, and on gamma-secretase complex formation. A loss in APP and Notch substrate processing at epsilon and S3 cleavage sites was observed with all presenilin mutants, whereas APP processing at the gamma site was affected in variable ways. PS1-Delta9 and PS1-L166P mutations caused a reduction in beta-amyloid peptide Abeta40 production whereas PS1-G384A mutant significantly increased Abeta42. Interestingly PS2, a close homologue of PS1, appeared to be a less efficient producer of Abeta than PS1. Finally, subtle differences in gamma-secretase complex assembly were observed. Overall, our results indicate that the different mutations in PS affect gamma-secretase structure or function in multiple ways. 相似文献