Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Snooker Structure-Based Pharmacophore Model Explains Differences in Agonist and Blocker Binding to Bitter Receptor hTAS2R39
    Roland, W.S.U. ; Sanders, M.P.A. ; Buren, L. van; Gouka, R.J. ; Gruppen, H. ; Vincken, J.P. ; Ritschel, T. - \ 2015
    PLoS ONE 10 (2015)3. - ISSN 1932-6203
    protein-coupled receptors - class-a gpcrs - taste receptors - activation - identification - requirements - peptides - family - assay - t2r1
    The human bitter taste receptor hTAS2R39 can be activated by many dietary (iso)flavonoids. Furthermore, hTAS2R39 activity can be blocked by 6-methoxyflavanones, 4’-fluoro-6-methoxyflavanone in particular. A structure-based pharmacophore model of the hTAS2R39 binding pocket was built using Snooker software, which has been used successfully before for drug design of GPCRs of the rhodopsin subfamily. For the validation of the model, two sets of compounds, both of which contained actives and inactives, were used: (i) an (iso)flavonoid-dedicated set, and (ii) a more generic, structurally diverse set. Agonists were characterized by their linear binding geometry and the fact that they bound deeply in the hTAS2R39 pocket, mapping the hydrogen donor feature based on T5.45 and N3.36, analogues of which have been proposed to play a key role in activation of GPCRs. Blockers lack hydrogen-bond donors enabling contact to the receptor. Furthermore, they had a crooked geometry, which could sterically hinder movement of the TM domains upon receptor activation. Our results reveal characteristics of hTAS2R39 agonist and bitter blocker binding, which might facilitate the development of blockers suitable to counter the bitterness of dietary hTAS2R39 agonists in food applications.
    Gender mainstreaming and rural development policy; the trivialisation of rural gender issues
    Bock, B.B. - \ 2015
    Gender, Place & Culture : a Journal of Feminist Geography 22 (2015)5. - ISSN 0966-369X - p. 731 - 745.
    european-union - mobilities - areas - state - work - eu - challenges - migration - politics - family
    This paper considers gender mainstreaming of the EU Rural Development Programme. The EU promotes the gender mainstreaming of rural development policies because retaining women in rural areas is seen as crucial to the long-term viability of rural areas. A review of literature and scan of policy documents demonstrates that few rural development plans address gender issues, and generally only by including some separate projects for women. Little is done to address the systemic features of gender inequality and to realise inclusive developments that address the needs of all social groups. The de-politicisation of rural gender issues results in policy makers ticking the obligatory gender box without envisioning any real change in the agenda or process of rural development policy making. I argue that a more fruitful way to go forward is to re-politicise gender in rural development and to tease out at the local level how changing gender relations and rural development coincide.
    Identification of reference genes for gene expression studies during seed germination and seedling establishment Ricinus communis L.
    Ribeiro de Jesus, P.R. ; Dekkers, S.J.W. ; Fernandez, L.G. ; Castro, R.D. De; Ligterink, W. ; Hilhorst, H.W.M. - \ 2014
    Seed Science Research 24 (2014)4. - ISSN 0960-2585 - p. 341 - 352.
    time rt-pcr - fatty-acid - jatropha-curcas - castor-oil - phosphoenolpyruvate carboxylase - arabidopsis - normalization - plant - cloning - family
    Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is an important technology to analyse gene expression levels during plant development or in response to different treatments. An important requirement to measure gene expression levels accurately is a properly validated set of reference genes. In this context, we analysed the potential use of 17 candidate reference genes across a diverse set of samples, including several tissues, different stages and environmental conditions, encompassing seed germination and seedling growth in Ricinus communis L. These genes were tested by RT-qPCR and ranked according to the stability of their expression using two different approaches: GeNorm and NormFinder. GeNorm and Normfinder indicated that ACT, POB and PP2AA1 comprise the optimal combination for normalization of gene expression data in inter-tissue (heterogeneous sample panel) studies. We also describe the optimal combination of reference genes for a subset of root, endosperm and cotyledon samples. In general, the most stable genes suggested by GeNorm are very consistent with those indicated by NormFinder, which highlights the strength of the selection of reference genes in our study. We also validated the selected reference genes by normalizing the expression levels of three target genes involved in energy metabolism with the reference genes suggested by GeNorm and NormFinder. The approach used in this study to identify stably expressed genes, and thus potential reference genes, was applied successfully for R. communis and it provides important guidelines for RT-qPCR studies in seeds and seedlings for other species (especially in those cases where extensive microarray data are not available)
    IL-37 protects against obesity-induced inflammation and insulin resistance
    Ballak, D.B. ; Diepen, J.A. van; Moschen, A.R. ; Jansen, H. ; Hijmans, A. ; Groenhof, G.J. ; Leenders, F. ; Bufler, P. ; Boekschoten, M.V. - \ 2014
    Nature Communications 5 (2014). - ISSN 2041-1723 - 12 p.
    white adipose-tissue - high-fat diet - human interleukin-1-alpha - innate immunity - beta-cells - mice - receptor - family - expression - members
    Cytokines of the IL-1 family are important modulators of obesity-induced inflammation and the development of systemic insulin resistance. Here we show that IL-1 family member ¿IL-37, recently characterized as an anti-inflammatory cytokine, ameliorates obesity-induced inflammation and insulin resistance. Mice transgenic for human ¿IL-37 (¿IL-37tg) exhibit reduced numbers of adipose tissue macrophages, increased circulating levels of ¿adiponectin and preserved ¿glucose tolerance and insulin sensitivity after 16 weeks of HFD. In vitro treatment of adipocytes with recombinant ¿IL-37 reduces adipogenesis and activates AMPK signalling. In humans, elevated steady-state ¿IL-37 adipose tissue mRNA levels are positively correlated with insulin sensitivity and a lower inflammatory status of the adipose tissue. These findings reveal ¿IL-37 as an important anti-inflammatory modulator during obesity-induced inflammation and insulin resistance in both mice and humans, and suggest that ¿IL-37 is a potential target for the treatment of obesity-induced insulin resistance and type 2 diabetes.
    Profiling the secretome and extracellular proteome of the potato late blight pathogen Phytophthora infestans
    Meijer, H.J.G. ; Mancuso, F.M. ; Espadas, G. ; Seidl, M.F. ; Chiva, C. ; Govers, F. ; Sabido, E. - \ 2014
    Molecular and Cellular Proteomics 13 (2014)8. - ISSN 1535-9476 - p. 2101 - 2113.
    phosphate kinase domain - amino-acid-sequence - cell-wall proteins - coupled receptors - genome sequence - identification - family - infection - virulence - effectors
    Oomycetes are filamentous organisms that cause notorious diseases, several of which have a high economic impact. Well known is Phytophthora infestans, the causal agent of potato late blight. Previously, in silico analyses of the genome and transcriptome of P. infestans resulted in the annotation of a large number of genes encoding proteins with an N-terminal signal peptide. This set is collectively referred to as the secretome and comprises proteins involved in, for example, cell wall growth and modification, proteolytic processes, and the promotion of successful invasion of plant cells. So far, proteomic profiling in oomycetes was primarily focused on subcellular, intracellular or cell wall fractions; the extracellular proteome has not been studied systematically. Here we present the first comprehensive characterization of the in vivo secretome and extracellular proteome of P. infestans. We have used mass spectrometry to analyze P. infestans proteins present in seven different growth media with mycelial cultures and this resulted in the consistent identification of over two hundred proteins. Gene ontology classification pinpointed proteins involved in cell wall modifications, pathogenesis, defense responses, and proteolytic processes. Moreover, we found members of the RXLR and CRN effector families as well as several proteins lacking an obvious signal peptide. The latter were confirmed to be bona fide extracellular proteins and this suggests that, similar to other organisms, oomycetes exploit non-conventional secretion mechanisms to transfer certain proteins to the extracellular environment.
    Functional analysis of the conserved transcriptional regulator CfWor1 in Cladosporium fulvum reveals diverse roles in the virulence of plant pathogenic fungi
    Ökmen, B. ; Collemare, J. ; Griffiths, S.A. ; Burgt, A. van der; Cox, R. ; Wit, P.J.G.M. de - \ 2014
    Molecular Microbiology 92 (2014)1. - ISSN 0950-382X - p. 10 - 27.
    avirulence gene avr9 - dna-binding domains - candida-albicans - alternaria-brassicicola - magnaporthe-grisea - master regulator - expression - tomato - family - penetration
    Fungal Wor1-like proteins are conserved transcriptional regulators that are reported to regulate the virulence of several plant pathogenic fungi by affecting the expression of virulence genes. Here, we report the functional analysis of CfWor1, the homologue of Wor1 in Cladosporium fulvum. ¿cfwor1 mutants produce sclerotium-like structures and rough hyphae, which are covered with a black extracellular matrix. These mutants do not sporulate and are no longer virulent on tomato. A CE.CfWor1 transformant that constitutively expresses CfWor1 produces fewer spores with altered morphology and is also reduced in virulence. RNA-seq and RT-qrtPCR analyses suggest that reduced virulence of ¿cfwor1 mutants is due to global downregulation of transcription, translation and mitochondrial respiratory chain. The reduced virulence of the CE.CfWor1 transformant is likely due to downregulation of effector genes. Complementation of a non-virulent ¿fosge1 (Wor1-homologue) mutant of Fusarium oxysporum f. sp. lycopersici with CfWor1 restored expression of the SIX effector genes in this fungus, but not its virulence. Chimeric proteins of CfWor1/FoSge1 also only partially restored defects of the ¿fosge1 mutant, suggesting that these transcriptional regulators have functionally diverged. Altogether, our results suggest that CfWor1 primarily regulates development of C.¿fulvum, which indirectly affects the expression of a subset of virulence genes.
    Systematic review on cashew nut allergy
    Valk, J.P.M. van der; Dubois, A.E.J. ; Wichers, H.J. ; Jong, N.W. de; Wijk, R. van - \ 2014
    Allergy 69 (2014). - ISSN 0105-4538 - p. 692 - 698.
    cross-reactivity - pistachio nut - clinical-features - peanut allergy - children - anaphylaxis - food - vicilin - family - ige
    Recent studies on cashew nut allergy suggest that the prevalence of cashew nut allergy is increasing. Cashew nut consumption by allergic patients can cause severe reactions, including anaphylaxis. This review summarizes current knowledge on cashew nut allergy to facilitate timely clinical recognition and to promote awareness of this emerging food allergy amongst clinicians. The goal of this study is to present a systematic review focused on the clinical aspects of allergy to cashew nut including the characteristics of cashew nut, the prevalence, allergenic components, cross-reactivity, diagnosis and management of cashew nut allergy. The literature search yielded 255 articles of which 40 met our selection criteria and were considered to be relevant for this review. The 40 articles included one prospective study, six retrospective studies and seven case reports. The remaining 26 papers were not directly related to cashew nut allergy. The literature suggests that the prevalence of cashew nut allergy is increasing, although the level of evidence for this is low. A minimal amount of cashew nut allergen may cause a severe allergic reaction, suggesting high potency comparable with other tree nuts and peanuts. Cashew allergy is clearly an underestimated important healthcare problem, especially in children.
    Structural Basis for DNA Binding Specificity by the Auxin-Dependent ARF Transcription Factors
    Boer, D.R. ; Freire Rios, A. ; Berg, W.A.M. van den; Saaki, T. ; Manfield, I.W. ; Kepinski, S. ; López-Vidrieo, I. ; Franco-Zorilla, J.M. ; Vries, S.C. de; Solano, R. ; Weijers, D. ; Coll, M. - \ 2014
    Cell 156 (2014). - ISSN 0092-8674 - p. 577 - 589.
    arabidopsis gene monopteros - response elements - vascular development - plant development - domains - family - embryo - embryogenesis - dimerization - recognition
    Auxin regulates numerous plant developmental processes by controlling gene expression via a family of functionally distinct DNA-binding auxin response factors (ARFs), yet the mechanistic basis for generating specificity in auxin response is unknown. Here, we address this question by solving high-resolution crystal structures of the pivotal Arabidopsis developmental regulator ARF5/MONOPTEROS (MP), its divergent paralog ARF1, and a complex of ARF1 and a generic auxin response DNA element (AuxRE). We show that ARF DNA-binding domains also homodimerize to generate cooperative DNA binding, which is critical for in vivo ARF5/MP function. Strikingly, DNA-contacting residues are conserved between ARFs, and we discover that monomers have the same intrinsic specificity. ARF1 and ARF5 homodimers, however, differ in spacing tolerated between binding sites. Our data identify the DNA-binding domain as an ARF dimerization domain, suggest that ARF dimers bind complex sites as molecular calipers with ARF-specific spacing preference, and provide an atomic-scale mechanistic model for specificity in auxin response.
    Lettuce necrotic leaf curl virus, a new plant virus infecting lettuce and a proposed member of the genus Torradovirus
    Verbeek, M. ; Dullemans, A.M. ; Raaij, H.M.G. van; Verhoeven, J.Th.J. ; Vlugt, R.A.A. van der - \ 2014
    Archives of Virology 159 (2014)4. - ISSN 0304-8608 - p. 801 - 805.
    stranded rna viruses - picorna-like virus - tomato - family
    A new virus was isolated from a lettuce plant grown in an open field in the Netherlands in 2011. This plant was showing conspicuous symptoms that consisted of necrosis and moderate leaf curling. The virus was mechanically transferred to indicator plants, and a total RNA extract of one of these indicator plants was used for next-generation sequencing. Analysis of the sequences that were obtained and further biological studies showed that the virus was related to, but clearly distinct from, viruses belonging to the genus Torradovirus. The name “lettuce necrotic leaf curl virus” (LNLCV) is proposed for this new torrad
    Sibling Position and Marriage Timing in the Netherlands, 1840-1922: A Comparison across Social Classes, Local Contexts, and Time
    Suanet, B. ; Bras, H. - \ 2014
    Journal of Family History 39 (2014)2. - ISSN 0363-1990 - p. 126 - 139.
    example - family
    Research on the effects of sibling position on marriage timing has produced ambivalent findings, suggesting that birth order effects were contingent on social, local, and historical contexts. Based on a large database of marriage certificates from five Dutch provinces between 1840 and 1922, we examine the influence of birth order on marriage timing. Our main conclusion is that sibling position became less important for marriage timing during the nineteenth century. This trend can be considered part of the transition from the West-European marriage pattern to a marriage pattern characterized by more universal marriage in which personal preferences became more significant.
    Characterisation of the transcriptome of Aphelenchoides besseyi and identification of a GHF 45 cellulase
    Kikuchi, T. ; Cock, P.J.A. ; Helder, J. ; Jones, J.T. - \ 2014
    Nematology 16 (2014)1. - ISSN 1388-5545 - p. 99 - 107.
    expressed sequence tags - nematode bursaphelenchus-xylophilus - horizontal gene-transfer - root-lesion nematode - radopholus-similis - plant parasitism - signal peptides - family - technology - tools
    While the majority of Aphelenchoides species are fungivorous, some species are plant parasites that have retained the ability to feed on fungi. Aphelenchoides besseyi is an important and widespread pathogen that causes ‘white tip’ disease on rice. This migratory endoparasitic nematode makes a significant contribution to the estimated $US 16 billion worth of damage caused by nematodes to rice crops. Here we describe a small-scale analysis of the transcriptome of A. besseyi. After sequencing, QC and assembly, approximately 5000 contigs were analysed. Bioinformatic analysis allowed 375 secreted proteins to be identified, including orthologues of proteins known to be secreted by other nematodes. One contig could encode an A. besseyi orthologue of a GHF45 cellulase, similar to those present in Bursaphelenchus xylophilus. No transcripts similar to GHF5 cellulases were present in this dataset.
    Auxin reflux between the endodermis and pericycle promotes lateral root initiation
    Marhavy, P. ; Vanstraelen, M. ; Rybel, B.P.M. de; Ding, Z.J. ; Bennett, M.J. ; Beeckman, T. ; Benkova, E. - \ 2013
    The EMBO Journal 32 (2013)1. - ISSN 0261-4189 - p. 149 - 158.
    arabidopsis-thaliana - gene-expression - cell-cycle - efflux - transport - family - organization - gradients - proteins - meristem
    Lateral root (LR) formation is initiated when pericycle cells accumulate auxin, thereby acquiring founder cell (FC) status and triggering asymmetric cell divisions, giving rise to a new primordium. How this auxin maximum in pericycle cells builds up and remains focused is not understood. We report that the endodermis plays an active role in the regulation of auxin accumulation and is instructive for FCs to progress during the LR initiation (LRI) phase. We describe the functional importance of a PIN3 (PIN-formed) auxin efflux carrier-dependent hormone reflux pathway between overlaying endodermal and pericycle FCs. Disrupting this reflux pathway causes dramatic defects in the progress of FCs towards the next initiation phase. Our data identify an unexpected regulatory function for the endodermis in LRI as part of the fine-tuning mechanism that appears to act as a check point in LR organogenesis after FCs are specified. The EMBO Journal (2013) 32, 149-158. doi:10.1038/emboj.2012.303; Published online 23 November 2012
    Complete Sequence of pSAM7, an IncX4 Plasmid Carrying a Novel blaCTX-M-14b Transposition Unit Isolated from Escherichia coli and Enterobacter cloacae from Cattle
    Stokes, M.O. ; Abuoun, M. ; Umur, S. ; Wu, G. ; Partridge, S.R. ; Mevius, D.J. ; Coldham, N.G. ; Fielder, M.D. - \ 2013
    Antimicrobial Agents and Chemotherapy 57 (2013)9. - ISSN 0066-4804 - p. 4590 - 4594.
    spectrum-beta-lactamases - klebsiella-pneumoniae - identification - gene - bacteria - strains - ctx-m-9 - humans - family
    The same plasmid carrying blaCTX-M-14b was identified from an Escherichia coli isolate and an Enterobacter cloacae isolate collected from cattle in the United Kingdom by complete plasmid sequencing. This 35,341-bp plasmid, pSAM7, had an IncX4 backbone that is 99% identical to that of pJIE143 from a human isolate in Australia. PCR screening identified pSAM7-like plasmids in three other E. coli isolates of different multilocus sequence types isolated from cattle on different farms in the United Kingdom.
    Loss of Function in Mlo Orthologs Reduces Susceptibility of Pepper and Tomato to Powdery Mildew Disease Caused by Leveillula taurica
    Zheng, Z. ; Nonomura, T. ; Appiano, M. ; Pavan, S.N.C. ; Matsuda, Y. ; Toyoda, H. ; Wolters, A.M.A. ; Visser, R.G.F. ; Bai, Y. - \ 2013
    PLoS ONE 8 (2013)7. - ISSN 1932-6203 - 14 p.
    real-time pcr - capsicum-annuum - subcellular-localization - nonhost resistance - gene-expression - oryza-sativa - cell-death - barley - family - identification
    Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse tomato and pepper production. In contrast to most powdery mildew species which are epiphytic, L. taurica is an endophytic fungus colonizing the mesophyll tissues of the leaf. In barley, Arabidopsis, tomato and pea, the correct functioning of specific homologues of the plant Mlo gene family has been found to be required for pathogenesis of epiphytic powdery mildew fungi. The aim of this study was to investigate the involvement of the Mlo genes in susceptibility to the endophytic fungus L. taurica. In tomato (Solanum lycopersicum), a loss-of-function mutation in the SlMlo1 gene results in resistance to powdery mildew disease caused by Oidium neolycopersici. When the tomato Slmlo1 mutant was inoculated with L. taurica in this study, it proved to be less susceptible compared to the control, S. lycopersicum cv. Moneymaker. Further, overexpression of SlMlo1 in the tomato Slmlo1 mutant enhanced susceptibility to L. taurica. In pepper, the CaMlo2 gene was isolated by applying a homology-based cloning approach. Compared to the previously identified CaMlo1 gene, the CaMlo2 gene is more similar to SlMlo1 as shown by phylogenetic analysis, and the expression of CaMlo2 is up-regulated at an earlier time point upon L. taurica infection. However, results of virus-induced gene silencing suggest that both CaMlo1 and CaMlo2 may be involved in the susceptibility of pepper to L. taurica. The fact that overexpression of CaMlo2 restored the susceptibility of the tomato Slmlo1 mutant to O. neolycopersici and increased its susceptibility to L. taurica confirmed the role of CaMlo2 acting as a susceptibility factor to different powdery mildews, though the role of CaMlo1 as a co-factor for susceptibility cannot be excluded.
    Women's identity as farmers: A case study from ten households in Syria
    Galiè, A. ; Jiggins, J.L.S. ; Struik, P.C. - \ 2013
    NJAS Wageningen Journal of Life Sciences 64-65 (2013). - ISSN 1573-5214 - p. 25 - 33.
    This article presents the results of a study on women's roles and identity as farmers, as perceived by 17 women and 24 men in three Syrian villages, which was carried out between 2007 and 2009 as part of long-term, in-depth research in these villages in the context of a participatory plant breeding programme. The findings reveal that understanding who is considered a farmer, at household and community levels, is biased by gender norms. Women in the study villages play substantial roles in farming and are increasingly involved in agricultural management, but they are generally overlooked or under-valued as farmers by both men and women, at the household and community levels. Men typically are considered to be ‘the farmers’ and women to be only their helpers. However, the findings also reveal a more nuanced understanding of the contribution of women and men to farming as households pragmatically deal with their needs and possibilities in the actual conditions they encounter. The article presents some of the reasons behind this ‘invisibility of women as farmers’, as understood by the respondents, and discusses the implications for the participatory plant breeding programme.
    Jasmonoyl-L-isoleucine hydrolase 1 (JIH1) regulates jasmonoyl-L-isoleucine levels and attenuates plant defenses against herbivores
    Woldemariam, M.G. ; Onkokesung, N. ; Baldwin, I.T. ; Galis, I. - \ 2012
    The Plant Journal 72 (2012)5. - ISSN 0960-7412 - p. 758 - 767.
    agrobacterium-mediated transformation - auxin conjugate hydrolase - nicotiana-attenuata - manduca-sexta - proteinase-inhibitors - arabidopsis-thaliana - insect herbivores - acid - responses - family
    For most plant hormones, biological activity is suppressed by reversible conjugation to sugars, amino acids and other small molecules. In contrast, the conjugation of jasmonic acid (JA) to isoleucine (Ile) is known to enhance the activity of JA. Whereas hydroxylation and carboxylation of JA-Ile permanently inactivates JA-Ilemediated signaling in plants, the alternative deactivation pathway of JA-Ile by its direct hydrolysis to JA remains unstudied. We show that Nicotiana attenuata jasmonoyl-L-isoleucine hydrolase 1 (JIH1), a close homologue of previously characterized indoleacetic acid alanine resistant 3 (IAR3) gene in Arabidopsis, hydrolyzes both JA-Ile and IAA-Ala in vitro. When the herbivory-inducible NaJIH1 gene was silenced by RNA interference, JA-Ile levels increased dramatically after simulated herbivory in irJIH1, compared with wild-type (WT) plants. When specialist (Manduca sexta) or generalist (Spodoptera littoralis) herbivores fed on irJIH1 plants they gained significantly less mass compared with those feeding on wild-type (WT) plants. The poor larval performance was strongly correlated with the higher accumulation of several JA-Ile-dependent direct defense metabolites in irJIH1 plants. In the field, irJIH1 plants attracted substantially more Geocoris predators to the experimentally attached M. sexta eggs on their leaves, compared with empty vector plants, which correlated with higher herbivory-elicited emissions of volatiles known to function as indirect defenses. We conclude that NaJIH1 encodes a new homeostatic step in JA metabolism that, together with JA and JA-Ilehydroxylation and carboxylation of JA-Ile, rapidly attenuates the JA-Ile burst, allowing plants to tailor the expression of direct and indirect defenses against herbivore attack in nature.
    Entpd5 is essential for skeletal mineralization and regulates phosphate homeostasis in zebrafish (online)
    Huitema, L.F.A. ; Apschner, A. ; Logister, I. ; Spoorendonk, K.M. ; Bussmann, J. ; Hammond, C.L. ; Schulte-Merker, S. - \ 2012
    Proceedings of the National Academy of Sciences of the United States of America 109 (2012)52. - ISSN 0027-8424 - p. 21372 - 21377.
    bone - model - osteoblasts - expression - calcification - members - cd39l4 - family - genes - acid
    Bone mineralization is an essential step during the embryonic development of vertebrates, and bone serves vital functions in human physiology. To systematically identify unique gene functions essential for osteogenesis, we performed a forward genetic screen in zebrafish and isolated a mutant, no bone (nob), that does not form any mineralized bone. Positional cloning of nob identified the causative gene to encode ectonucleoside triphosphate/diphosphohydrolase 5 (entpd5); analysis of its expression pattern demonstrates that entpd5 is specifically expressed in osteoblasts. An additional mutant, dragonfish (dgf), exhibits ectopic mineralization in the craniofacial and axial skeleton and encodes a loss-of-function allele of ectonucleotide pyrophosphatase phosphodiesterase 1 (enpp1). Intriguingly, generation of double-mutant nob/dgf embryos restored skeletal mineralization in nob mutants, indicating that mechanistically, Entpd5 and Enpp1 act as reciprocal regulators of phosphate/pyrophosphate homeostasis in vivo. Consistent with this, entpd5 mutant embryos can be rescued by high levels of inorganic phosphate, and phosphate-regulating factors, such as fgf23 and npt2a, are significantly affected in entpd5 mutant embryos. Our study demonstrates that Entpd5 represents a previously unappreciated essential player in phosphate homeostasis and skeletal mineralization.
    Mycorrhizal symbiosis: ancient signalling mechanisms co-opted
    Geurts, R. ; Vleeshouwers, V.G.A.A. - \ 2012
    Current Biology 22 (2012)23. - ISSN 0960-9822 - p. R997 - R999.
    medicago-truncatula - transcription - requires - family - cutin - nsp1
    Mycorrhizal root endosymbiosis is an ancient property of land plants. Two parallel studies now provide novel insight into the mechanism driving this interaction and how it is used by other filamentous microbes like pathogenic oomycetes.
    The lipid droplet coat protein perilipin 5 also localizes to muscle mitochondria
    Bosma, M. ; Minnaard, R. ; Sparks, L.M. ; Schaart, G. ; Losen, M. ; Baets, M.H. de; Duimel, H. ; Kersten, A.H. ; Bickel, P.E. ; Schrauwen, P. ; Hesselink, M.K.C. - \ 2012
    Histochemistry and Cell Biology 137 (2012)2. - ISSN 0948-6143 - p. 205 - 216.
    carnitine-palmitoyltransferase-i - human skeletal-muscle - substrate metabolism - lipolysis - adipocytes - peptides - promotes - tissues - family - signal
    Perilipin 5 (PLIN5/OXPAT) is a lipid droplet (LD) coat protein mainly present in tissues with a high fat-oxidative capacity, suggesting a role for PLIN5 in facilitating fatty acid oxidation. Here, we investigated the role of PLIN5 in fat oxidation in skeletal muscle. In human skeletal muscle, we observed that PLIN5 (but not PLIN2) protein content correlated tightly with OXPHOS content and in rat muscle PLIN5 content correlated with mitochondrial respiration rates on a lipid-derived substrate. This prompted us to examine PLIN5 protein expression in skeletal muscle mitochondria by means of immunogold electron microscopy and Western blots in isolated mitochondria. These data show that PLIN5, in contrast to PLIN2, not only localizes to LD but also to mitochondria, possibly facilitating fatty acid oxidation. Unilateral overexpression of PLIN5 in rat anterior tibialis muscle augmented myocellular fat storage without increasing mitochondrial density as indicated by the lack of change in protein content of five components of the OXPHOS system. Mitochondria isolated from PLIN5 overexpressing muscles did not possess increased fatty acid respiration. Interestingly though, (14)C-palmitate oxidation assays in muscle homogenates from PLIN5 overexpressing muscles revealed a 44.8% (P = 0.05) increase in complete fatty acid oxidation. Thus, in mitochondrial isolations devoid of LD, PLIN5 does not augment fat oxidation, while in homogenates containing PLIN5-coated LD, fat oxidation is higher upon PLIN5 overexpression. The presence of PLIN5 in mitochondria helps to understand why PLIN5, in contrast to PLIN2, is of specific importance in fat oxidative tissues. Our data suggests involvement of PLIN5 in directing fatty acids from the LD to mitochondrial fatty acid oxidation.
    Different Auxin Response Machineries Control Distinct Cell Fates in the Early Plant Embryo
    Rademacher, E.H. ; Lokerse, A.S. ; Schlereth, A. ; Llavata Peris, C.I. ; Bayer, M. ; Kientz, M. ; Freire Rios, A. ; Borst, J.W. ; Lukowitz, W. ; Juergens, G. ; Weijers, D. - \ 2012
    Developmental Cell 22 (2012)1. - ISSN 1534-5807 - p. 211 - 222.
    arabidopsis embryo - transcription factor - seed development - expression map - root-meristem - aux/iaa genes - proteins - monopteros - family - transformation
    The cell types of the plant root are first specified early during embryogenesis and are maintained throughout plant life. Auxin plays an essential role in embryonic root initiation, in part through the action of the ARF5/MP transcription factor and its auxin-labile inhibitor IAA12/BDL. MP and BDL function in embryonic cells but promote auxin transport to adjacent extraembryonic suspensor cells, including the quiescent center precursor (hypophysis). Here we show that a cell-autonomous auxin response within this cell is required for root meristem initiation. ARF9 and redundant ARFs, and their inhibitor IAA10, act in suspensor cells to mediate hypophysis specification and, surprisingly, also to prevent transformation to embryo identity. ARF misexpression, and analysis of the short suspensor mutant, demonstrates that lineage-specific expression of these ARFs is required for normal embryo development. These results imply the existence of a prepattern for a cell-type-specific auxin response that underlies the auxin-dependent specification of embryonic cell types
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