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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    Genomic Regions Associated With Skeletal Type Traits in Beef and Dairy Cattle Are Common to Regions Associated With Carcass Traits, Feed Intake and Calving Difficulty
    Doyle, Jennifer L. ; Berry, Donagh P. ; Veerkamp, Roel F. ; Carthy, Tara R. ; Walsh, Siobhan W. ; Evans, Ross D. ; Purfield, Deirdre C. - \ 2020
    Frontiers in Genetics Livestock Genomics 11 (2020). - ISSN 1664-8021
    cattle - genome-wide association study - linear type traits - sequence - single nucleotide polymorphism - skeletal

    Linear type traits describing the skeletal characteristics of an animal are moderately to strongly genetically correlated with a range of other performance traits in cattle including feed intake, reproduction traits and carcass merit; thus, type traits could also provide useful insights into the morphological differences among animals underpinning phenotypic differences in these complex traits. The objective of the present study was to identify genomic regions associated with five subjectively scored skeletal linear traits, to determine if these associated regions are common in multiple beef and dairy breeds, and also to determine if these regions overlap with those proposed elsewhere to be associated with correlated performance traits. Analyses were carried out using linear mixed models on imputed whole genome sequence data separately in 1,444 Angus, 1,129 Hereford, 6,433 Charolais, 8,745 Limousin, 1,698 Simmental, and 4,494 Holstein-Friesian cattle, all scored for the linear type traits. There was, on average, 18 months difference in age at assessment of the beef versus the dairy animals. While the majority of the identified quantitative trait loci (QTL), and thus genes, were both trait-specific and breed-specific, a large-effect pleiotropic QTL on BTA6 containing the NCAPG and LCORL genes was associated with all skeletal traits in the Limousin population and with wither height in the Angus. Other than that, little overlap existed in detected QTLs for the skeletal type traits in the other breeds. Only two QTLs overlapped the beef and dairy breeds; both QTLs were located on BTA5 and were associated with height in both the Angus and the Holstein-Friesian, despite the difference in age at assessment. Several detected QTLs in the present study overlapped with QTLs documented elsewhere that are associated with carcass traits, feed intake, and calving difficulty. While most breeding programs select for the macro-traits like carcass weight, carcass conformation, and feed intake, the higher degree of granularity with selection on the individual linear type traits in a multi-trait index underpinning the macro-level goal traits, presents an opportunity to help resolve genetic antagonisms among morphological traits in the pursuit of the animal with optimum performance metrics.

    Genetic Characterization of Porcine Circovirus Type 2 (PCV2) in Pigs of Bhutan
    Monger, V.R. ; Loeffen, W.L.A. ; Kus, K. ; Stegeman, J.A. ; Dukpa, K. ; Szymanek, K. ; Podgórska, K. - \ 2017
    Transboundary and Emerging Diseases 64 (2017)2. - ISSN 1865-1674 - p. 442 - 448.
    Bhutan - genome - phylogenetic analysis - pigs - porcine circovirus type 2 - sequence

    Porcine circovirus (PCV) is a small non-enveloped virus with a single-stranded circular DNA with two antigenically and genetically different species, PCV1 and PCV2. Among these two, PCV2 is responsible for multifactorial disease syndromes, the most important disease known as PCV2-systemic disease (PCV2-SD), previously known as post-weaning multisystemic wasting syndrome (PMWS). The epidemiological situation is dynamically changing and new strains including recombinant PCV2 have emerged in Asia. In Bhutan, pigs are important livestock and play a very important role in providing meat and income for rural farmers. Although high rate of pigs seropositive against PCV2 was described in Bhutan, there was no virological evidence for PCV2 infections. This study was conducted to confirm the presence of PCV2 through detection of PCV2 DNA and molecular characterization of PCV2 strains in tissue and blood samples collected from Bhutanese pigs. Porcine circovirus type 2 genome was detected in 16 of 34 tissue samples pigs from the government farm. In 9 pigs, very high level of viral replication indicated that PCV2-SD was detected. Phylogenetic analysis performed with a set of GenBank sequences revealed that the Bhutanese PCV2 strains belonged to the PCV2b genotype and grouped with cluster 1C.

    Novel introner-like elements in fungi are involved in parallel gains of spliceosomal introns
    Collemare, J. ; Beenen, H.G. ; Crous, P.W. ; Wit, P.J.G.M. de; Burgt, A. van der - \ 2015
    PLoS ONE 10 (2015)6. - ISSN 1932-6203 - 12 p.
    daphnia populations - maximum-likelihood - evolution - gene - positions - conservation - selection - sequence - genomes
    Spliceosomal introns are key components of the eukaryotic gene structure. Although they contributed to the emergence of eukaryotes, their origin remains elusive. In fungi, they might originate from the multiplication of invasive introns named Introner-Like Elements (ILEs). However, so far ILEs have been observed in six fungal species only, including Fulvia fulva and Dothistroma septosporum (Dothideomycetes), arguing against ILE insertion as a general mechanism for intron gain. Here, we identified novel ILEs in eight additional fungal species that are phylogenetically related to F. fulva and D. septosporum using PCR amplification with primers derived from previously identified ILEs. The ILE content appeared unique to each species, suggesting independent multiplication events. Interestingly, we identified four genes each containing two gained ILEs. By analysing intron positions in orthologues of these four genes in Ascomycota, we found that three ILEs had inserted within a 15 bp window that contains regular spliceosomal introns in other fungal species. These three positions are not the result of intron sliding because ILEs are newly gained introns. Furthermore, the alternative hypothesis of an inferred ancestral gain followed by independent losses contradicts the observed degeneration of ILEs. These observations clearly indicate three parallel intron gains in four genes that were randomly identified. Our findings suggest that parallel intron gain is a phenomenon that has been highly underestimated in ILE-containing fungi, and likely in the whole fungal kingdom.
    Phylogenetic analysis of highly pathogenic avian influenza A (H5N8) virus outbreak strains provides evidence for four separate introductions and one between-poultry farm transmission in the Netherlands, November 2014
    Bouwstra, R.J. ; Koch, G. ; Heutink, C.G. ; Harders, F.L. ; Spek, A. van der; Elbers, A.R.W. ; Bossers, A. - \ 2015
    Eurosurveillance 20 (2015)26. - ISSN 1025-496X
    mitochondrial-dna - a viruses - sequence - amplification - china - h5
    Phylogenetic analysis of highly pathogenic avian influenza A(H5N8) virus strains causing outbreaks in Dutch poultry farms in 2014 provides evidence for separate introduction of the virus in four outbreaks in farms located 16–112 km from each other and for between-farm transmission between the third and fourth outbreak in farms located 550 m from each other. In addition, the analysis showed that all European and two Japanese H5N8 virus strains are very closely related and seem to originate from a calculated common ancestor, which arose between July and September 2014. Our findings suggest that the Dutch outbreak virus strain ‘Ter Aar’ and the first German outbreak strain from 2014 shared a common ancestor. In addition, the data indicate that the Dutch outbreak viruses descended from an H5N8 virus that circulated around 2009 in Asia, possibly China, and subsequently spread to South Korea and Japan and finally also to Europe. Evolution of the virus seemed to follow a parallel track in Japan and Europe, which supports the hypothesis that H5N8 virus was exchanged between migratory wild waterfowl at their breeding grounds in Siberia and from there was carried by migrating waterfowl to Europe.
    Genome-wide transcriptional profiling of Clostridium perfringens SM101 during sporulation extends the core of putative sporulation genes and genes determining spore properties and germination characteristics
    Xiao, Y. ; Hijum, S.A.F.T. van; Abee, T. ; Wells-Bennik, M.H.J. - \ 2015
    PLoS ONE 10 (2015)5. - ISSN 1932-6203 - 19 p.
    bacillus-subtilis - dipicolinic acid - bacterial-spores - heat-resistance - ser/thr kinase - killing factor - identification - difficile - proteins - sequence
    The formation of bacterial spores is a highly regulated process and the ultimate properties of the spores are determined during sporulation and subsequent maturation. A wide variety of genes that are expressed during sporulation determine spore properties such as resistance to heat and other adverse environmental conditions, dormancy and germination responses. In this study we characterized the sporulation phases of C. perfringens enterotoxic strain SM101 based on morphological characteristics, biomass accumulation (OD600), the total viable counts of cells plus spores, the viable count of heat resistant spores alone, the pH of the supernatant, enterotoxin production and dipicolinic acid accumulation. Subsequently, whole-genome expression profiling during key phases of the sporulation process was performed using DNA microarrays, and genes were clustered based on their time-course expression profiles during sporulation. The majority of previously characterized C. perfringens germination genes showed upregulated expression profiles in time during sporulation and belonged to two main clusters of genes. These clusters with up-regulated genes contained a large number of C. perfringens genes which are homologs of Bacillus genes with roles in sporulation and germination; this study therefore suggests that those homologs are functional in C. perfringens. A comprehensive homology search revealed that approximately half of the upregulated genes in the two clusters are conserved within a broad range of sporeforming Firmicutes. Another 30% of upregulated genes in the two clusters were found only in Clostridium species, while the remaining 20% appeared to be specific for C. perfringens. These newly identified genes may add to the repertoire of genes with roles in sporulation and determining spore properties including germination behavior. Their exact roles remain to be elucidated in future studies.
    Genomics and the challenging translation into conservation practice
    Shafer, A.B.A. ; Wolf, J.B.W. ; Alves, P.C. ; Bergstrom, L. ; Bruford, M.W. ; Brannstrom, I. ; Colling, G. ; Dalen, L. van; Meester, L. de; Ekblom, R. ; Vergeer, P. - \ 2015
    Trends in Ecology and Evolution 30 (2015)2. - ISSN 0169-5347 - p. 78 - 87.
    genetic diversity - background selection - population genomics - insular population - dna - divergence - speciation - evolution - sequence - markers
    The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.
    Identification of Spodoptera exigua nucleopolyhedrovirus genes involved in pathogenicity and virulence
    Serrano, A. ; Pijlman, G.P. ; Vlak, J.M. ; Muñoz, D. ; Williams, T. ; Caballero, P. - \ 2015
    Journal of Invertebrate Pathology 126 (2015). - ISSN 0022-2011 - p. 43 - 50.
    in-vitro - multiple nucleopolyhedrovirus - myristoylated proteins - baculovirus - sequence - prediction - deletion - finger - genome - vivo
    Genome sequence analysis of seven different Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) isolates that differed in insecticidal phenotype permitted the identification of genes likely to be involved in pathogenicity of occlusion bodies (OBs) and speed of kill (virulence) of this virus: se4 (hoar), se5 (unknown function), se28 (unknown function), se76 (cg30), se87 (p26) and se129 (p26). To study the role of these genes experimentally on the insecticidal phenotype, a bacmid-based recombination system was constructed to delete selected genes from a SeMNPV isolate, VT-SeAL1, designated as SeBacAL1. All of the knockout viruses were viable and the repair viruses behaved like the wild-type control, vSeBacAL1. Deletion of se4, se5, se76 and se129 resulted in decreased OB pathogenicity compared to vSeBacAL1 OBs. In contrast, deletion of se87 did not significantly affect OB pathogenicity, whereas deletion of se28 resulted in significantly increased OB pathogenicity. Deletion of se4, se28, se76, se87 and se129 did not affect speed of kill compared to the bacmid vSeBacAL1, whereas speed of kill was significantly extended following deletion of se5 and in the wild-type isolate (SeAL1), compared to that of the bacmid. Therefore, biological assays confirmed that several genes had effects on virus insecticidal phenotype. Se5 is an attractive candidate gene for further studies, as it affects both biological parameters of this important biocontrol virus.
    The heat shock transcription factor PsHSF1 of Phytophthora sojae is required for oxidative stress tolerance and detoxifying the plant oxidative burst
    Sheng, Yuting ; Wang, Yonglin ; Meijer, H.J.G. ; Yang, Xinyu ; Hua, C. ; Ye, Wenwu ; Tao, Kai ; Liu, Xiaoyun ; Govers, F. ; Wang, Yuanchao - \ 2015
    Environmental Microbiology 17 (2015)4. - ISSN 1462-2912 - p. 1351 - 1364.
    signal-transduction - in-vivo - pathogen - infestans - expression - sequence - defense - laccase - binding - yeast
    In the interaction between plant and microbial pathogens, reactive oxygen species (ROS) rapidly accumulate upon pathogen recognition at the infection site and play a central role in plant defence. However, the mechanisms that plant pathogens use to counteract ROS are still poorly understood especially in oomycetes, filamentous organisms that evolved independently from fungi. ROS detoxification depends on transcription factors (TFs) that are highly conserved in fungi but much less conserved in oomycetes. In this study, we identified the TF PsHSF1 that acts as a modulator of the oxidative stress response in the soybean stem and root rot pathogen Phytophthora sojae. We found that PsHSF1 is critical for pathogenicity in P.¿sojae by detoxifying the plant oxidative burst. ROS produced in plant defence can be detoxified by extracellular peroxidases and laccases which might be regulated by PsHSF1. Our study extends the understanding of ROS detoxification mechanism mediated by a heat shock TF in oomycetes.
    Bovine Neonatal Pancytopenia is a heritable trait of the dam rather than the calf and correlates with the magnitude of vaccine induced maternal alloantibodies not the MHC haplotype
    Benedictus, L. ; Otten, H.G. ; Schaik, G. van; Ginkel, G.J. ; Heuven, H.C.M. ; Nielen, M. ; Rutten, V.P.M.G. ; Koets, A.P. - \ 2014
    Veterinary Research 45 (2014). - ISSN 0928-4249 - 13 p.
    class-i genes - hemorrhagic diathesis - cattle - antibody - calves - bnp - association - responses - sequence - beta-2-microglobulin
    Bovine Neonatal Pancytopenia (BNP), a bleeding syndrome of neonatal calves, is caused by alloantibodies absorbed from the colostrum of particular cows. A commercial BVD vaccine is the likely source of alloantigens eliciting BNP associated alloantibodies. We hypothesized that the rare occurrence of BNP in calves born to vaccinated dams could be associated with genetic differences within dams and calves. We found that the development of BNP within calves was a heritable trait for dams, not for calves and had a high heritability of 19%. To elucidate which genes play a role in the development of BNP we sequenced candidate genes and characterized BNP alloantibodies. Alloantigens present in the vaccine have to be presented to the dam’s immune system via MHC class II, however sequencing of DRB3 showed no differences in MHC class II haplotype between BNP and non-BNP dams. MHC class I, a highly polymorphic alloantigen, is an important target of BNP alloantibodies. Using a novel sequence based MHC class I typing method, we found no association of BNP with MHC class I haplotype distribution in dams or calves. Alloantibodies were detected in both vaccinated BNP and non-BNP dams and we found no differences in alloantibody characteristics between these groups, but alloantibody levels were significantly higher in BNP dams. We concluded that the development of BNP in calves is a heritable trait of the dam rather than the calf and genetic differences between BNP and non-BNP dams are likely due to genes controlling the quantitative alloantibody response following vaccination.
    Analysis of the A-U rich hairpin from the intergenic region of tospovirus S RNA as target and inducer of RNA silencing
    Hedil, M. ; Hassani-Mehraban, A. ; Lohuis, D. ; Kormelink, R.J.M. - \ 2014
    PLoS ONE 9 (2014)9. - ISSN 1932-6203 - 10 p.
    spotted-wilt-virus - small interfering rnas - double-stranded-rna - viral suppressors - gene - protein - plants - sequence - arabidopsis - resistance
    Earlier work indicated that Tomato spotted wilt virus (TSWV) messenger transcripts, and not the (anti)genomic RNAs, are targeted by the RNA silencing machinery. Here, the predicted AU-rich hairpin (HP) structure encoded by the intergenic region (IGR) of the TSWV S RNA, and present at the 3' end of viral mRNAs, was analyzed as a target and inducer for RNA silencing. Virus-derived siRNAs (vsiRNAs) purified from virus infected plants were found to derive from all three genomic RNA segments but predominantly the ambisense M and S RNAs. Further profiling on the S RNA sequence revealed that vsiRNAs were found from almost the entire S RNA sequence, except the IGR from where hardly any vsiRNAs were found. Similar profiles were observed with the distantly related Tomato yellow ring tospovirus (TYRV). Dicer cleavage assays using Drosophila melanogaster (Dm) embryo extracts showed that synthetic transcripts of the IGR-HP region were recognized as substrate for Dicer. Transient agroinfiltration assays of a GFP-sensor construct containing the IGR-HP sequence at its 3' UTR (GFP-HP) did not show more rapid/strong silencing and profiling of the corresponding siRNAs, generated outside the context of a viral infection, still revealed relatively low levels of IGR-HP-derived siRNAs. These data support the idea that the IGR-HP is a weak inducer of RNA silencing and only plays a minor role in the amplification of a strong antiviral RNAi response.
    Extensive expansion of A1 family aspartic proteinases in fungi revealed by evolutionary analyses of 107 complete eukaryotic proteomes
    Revuelta, M.V. ; Kan, J.A.L. van; Kay, J. ; Have, A. ten - \ 2014
    Genome Biology and Evolution 6 (2014)6. - ISSN 1759-6653 - p. 1480 - 1494.
    botrytis-cinerea secretome - x-ray analyses - candida-albicans - saccharomyces-cerevisiae - phylogenetic trees - unique member - sequence - proteases - prediction - nepenthesin
    The A1 family of eukaryotic aspartic proteinases (APs) forms one of the 16 AP families. Although one of the best characterized families, the recent increase in genome sequence data has revealed many fungal AP homologs with novel sequence characteristics. This study was performed to explore the fungal AP sequence space and to obtain an in-depth understanding of fungal AP evolution. Using a comprehensive phylogeny of approximately 700 AP sequences from the complete proteomes of 87 fungi and 20 nonfungal eukaryotes, 11 major clades of APs were defined of which clade I largely corresponds to the A1A subfamily of pepsin-archetype APs. Clade II largely corresponds to the A1B subfamily of nepenthesin-archetype APs. Remarkably, the nine other clades contain only fungal APs, thus indicating that fungal APs have undergone a large sequence diversification. The topology of the tree indicates that fungal APs have been subject to both “birth and death” evolution and “functional redundancy and diversification.” This is substantiated by coclustering of certain functional sequence characteristics. A meta-analysis toward the identification of Cluster Determining Positions (CDPs) was performed in order to investigate the structural and biochemical basis for diversification. Seven CDPs contribute to the secondary structure of the enzyme. Three other CDPs are found in the vicinity of the substrate binding cleft. Tree topology, the large sequence variation among fungal APs, and the apparent functional diversification suggest that an amendment to update the current A1 AP classification based on a comprehensive phylogenetic clustering might contribute to refinement of the classification in the MEROPS peptidase database.
    Green genes: bioinformatics and systems-biology innovations drive algal biotechnology
    Reijnders, M.J.M.F. ; Heck, R.G.A. van; Lam, C.M.C. ; Scaife, M.A. ; Martins dos Santos, V.A.P. ; Smith, A.G. ; Schaap, P.J. - \ 2014
    Trends in Biotechnology 32 (2014)12. - ISSN 0167-7799 - p. 617 - 626.
    protein function prediction - subcellular-localization prediction - metabolic network reconstruction - flux balance analysis - chlamydomonas-reinhardtii - lipid-accumulation - expression data - genome - microalgae - sequence
    Many species of microalgae produce hydrocarbons, polysaccharides, and other valuable products in significant amounts. However, large-scale production of algal products is not yet competitive against non-renewable alternatives from fossil fuel. Metabolic engineering approaches will help to improve productivity, but the exact metabolic pathways and the identities of the majority of the genes involved remain unknown. Recent advances in bioinformatics and systems-biology modeling coupled with increasing numbers of algal genome-sequencing projects are providing the means to address this. A multidisciplinary integration of methods will provide synergy for a systems-level understanding of microalgae, and thereby speed up the improvement of industrially valuable strains. In this review we highlight recent advances, challenges, their application in microalgae research, and their potential.
    Genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida
    Thorpe, P. ; Mantelin, S. ; Cock, P.J.A. ; Blok, V.C. ; Coke, M.C. ; Evers-van den Akker, S. ; Guzeeva, E. ; Lilley, C.J. ; Smant, G. ; Reid, A.J. ; Wright, K.M. ; Urwin, P.E. ; Jones, J.T. - \ 2014
    BMC Genomics 15 (2014). - ISSN 1471-2164 - 15 p.
    plant-parasitic nematodes - esophageal gland-cells - heterodera-glycines - meloidogyne-incognita - phytophthora-infestans - arabidopsis-thaliana - chorismate mutase - giant-cells - protein - sequence
    Background The potato cyst nematode Globodera pallida has biotrophic interactions with its host. The nematode induces a feeding structure – the syncytium – which it keeps alive for the duration of the life cycle and on which it depends for all nutrients required to develop to the adult stage. Interactions of G. pallida with the host are mediated by effectors, which are produced in two sets of gland cells. These effectors suppress host defences, facilitate migration and induce the formation of the syncytium. Results The recent completion of the G. pallida genome sequence has allowed us to identify the effector complement from this species. We identify 128 orthologues of effectors from other nematodes as well as 117 novel effector candidates. We have used in situ hybridisation to confirm gland cell expression of a subset of these effectors, demonstrating the validity of our effector identification approach. We have examined the expression profiles of all effector candidates using RNAseq; this analysis shows that the majority of effectors fall into one of three clusters of sequences showing conserved expression characteristics (invasive stage nematode only, parasitic stage only or invasive stage and adult male only). We demonstrate that further diversity in the effector pool is generated by alternative splicing. In addition, we show that effectors target a diverse range of structures in plant cells, including the peroxisome. This is the first identification of effectors from any plant pathogen that target this structure. Conclusion This is the first genome scale search for effectors, combined to a life-cycle expression analysis, for any plant-parasitic nematode. We show that, like other phylogenetically unrelated plant pathogens, plant parasitic nematodes deploy hundreds of effectors in order to parasitise plants, with different effectors required for different phases of the infection process.
    Determination of the Influence of Substrate Concentration on Enzyme Selectivity Using Whey Protein Isolate and Bacillus licheniformis Protease
    Butré, C.I. ; Sforza, S. ; Gruppen, H. ; Wierenga, P.A. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)42. - ISSN 0021-8561 - p. 10230 - 10239.
    beta-lactoglobulin - functional-properties - mass-spectrometry - hydrolysis - peptide - endopeptidase - sequence - casein - model
    Increasing substrate concentration during enzymatic protein hydrolysis results in a decrease in hydrolysis rate. To test if changes in the mechanism of hydrolysis also occur, the enzyme selectivity was determined. The selectivity is defined quantitatively as the relative rate of hydrolysis of each cleavage site in the protein. It was determined from the identification and quantification of the peptides present in the hydrolysates. Solutions of 0.1–10% (w/v) whey protein isolate (WPI) were hydrolyzed by Bacillus licheniformis protease at constant enzyme-to-substrate ratio. The cleavage sites were divided into five groups, from very high (>10%) to very low selectivity (
    From micelles to fibers: balancing self-assembling and random coiling domains in pH-responsive silk-collagen-like protein-based polymers
    Beun, L.H. ; Storm, I.M. ; Werten, M.W.T. ; Wolf, F.A. de; Cohen Stuart, M.A. ; Vries, R.J. de - \ 2014
    Biomacromolecules 15 (2014)9. - ISSN 1525-7797 - p. 3349 - 3357.
    elastin-like polypeptide - periodic polypeptides - pichia-pastoris - copolymers - hydrogels - sequence - nanoparticles - biosynthesis - secretion - networks
    We study the self-assembly of genetically engineered protein-based triblock copolymers consisting of a central pH-responsive silk-like middle block (SHn, where SH is a silk-like octapeptide, (GA)3GH and n is the number of repeats) flanked by hydrophilic random coil outer blocks (C2). Our previous work has already shown that triblocks with very long midblocks (n = 48) self-assemble into long, stiff protein filaments at pH values where the middle blocks are uncharged. Here we investigate the self-assembly behavior of the triblock copolymers for a range of midblock lengths, n = 8, 16, 24, 48. Upon charge neutralization of SHn by adjusting the pH, we find that C2SH8C2 and C2SH16C2 form spherical micelles, whereas both C2SH24C2 and C2SH48C2 form protein filaments with a characteristic beta-roll secondary structure of the silk midblocks. Hydrogels formed by C2SH48C2 are much stronger and form much faster than those formed by C2SH24C2. Enzymatic digestion of much of the hydrophilic outer blocks is used to show that with much of the hydrophilic outer blocks removed, all silk-midblocks are capable of self-assembling into stiff protein filaments. In that case, reduction of the steric repulsion by the hydrophilic outer blocks also leads to extensive fiber bundling. Our results highlight the opposing roles of the hydrophilic outer blocks and central silk-like midblocks in driving protein filament formation. They provide crucial information for future designs of triblock protein-based polymers that form stiff filaments with controlled bundling, that could mimick properties of collagen in the extracellular matrix.
    Bacillus anthracis-like bacteria and other B. cereus group members in a microbial community within the international space station: a challenge for rapid and easy molecular detection of virulent B. anthracis.
    Tongeren, S.P. van; Roest, H.I.J. ; Degener, J.E. ; Harmsen, H.J.M. - \ 2014
    PLoS ONE 9 (2014)9. - ISSN 1932-6203
    polymerase-chain-reaction - toxin genes - identification - purification - sequence - strains - gyrb
    For some microbial species, such as Bacillus anthracis, the etiologic agent of the disease anthrax, correct detection and identification by molecular methods can be problematic. The detection of virulent B. anthracis is challenging due to multiple virulence markers that need to be present in order for B. anthracis to be virulent and its close relationship to Bacillus cereus and other members of the B. cereus group. This is especially the case in environments where build-up of Bacillus spores can occur and several representatives of the B. cereus group may be present, which increases the chance for false-positives. In this study we show the presence of B. anthracis-like bacteria and other members of the B. cereus group in a microbial community within the human environment of the International Space Station and their preliminary identification by using conventional culturing as well as molecular techniques including 16S rDNA sequencing, PCR and real-time PCR. Our study shows that when monitoring the microbial hygiene in a given human environment, health risk assessment is troublesome in the case of virulent B. anthracis, especially if this should be done with rapid, easy to apply and on-site molecular methods.
    Field vaccinated chickens with low antibody titres show equally insufficient protection against matching and non-matching genotypesof virulent Newcastle disease virus
    Dortmans, J.C.F.M. ; Venema-Kemper, S. ; Peeters, B.P.H. ; Koch, G. - \ 2014
    Veterinary Microbiology 172 (2014)1-2. - ISSN 0378-1135 - p. 100 - 107.
    shedding following vaccination - wild-type - outbreaks - strains - sequence - china - pathogenesis - challenge - genetics - poultry
    Newcastle disease (ND) is a severe threat to the poultry industry and is caused by virulent strains of Newcastle disease virus (NDV). Many countries maintain a vaccination policy, but NDV is rapidly evolving as shown by the discovery of several new genotypes in the last decades. We tested the efficacy of the currently used classical commercial ND vaccine based on the genotype II strain VG/GA, applied under standard field conditions, against outbreak strains. Field vaccinated broilers were challenged with four different viruses belonging to genotype II, V or VII. A large proportion of field vaccinated broilers showed suboptimal immunity and the protection level against early and recent NDV isolates was dramatically low. Furthermore, there were no significant differences in protection afforded by a genotype II vaccine against a genotype II virus challenge compared to a challenge with viruses belonging to the other genotypes. This study suggests that the susceptibility of vaccinated poultry to NDV infection is not the result of vaccine mismatch, but rather of poor vaccination practices
    DNA-guided DNA interference by a prokaryotic Argonaute
    Swarts, D.C. ; Jore, M.M. ; Westra, E.R. ; Zhu, Y. ; Janssen, J.H. ; Snijders, A.P. ; Wang, Y. ; Patel, D.J. ; Berenguer, J. ; Brouns, S.J.J. ; Oost, J. van der - \ 2014
    Nature 507 (2014)7491. - ISSN 0028-0836 - p. 258 - 261.
    thermophile thermus-thermophilus - silencing complex - structural basis - rna - archaebacteria - recognition - eubacteria - cleavage - sequence - protein
    RNA interference is widely distributed in eukaryotes and has a variety of functions, including antiviral defence and gene regulation. All RNA interference pathways use small single-stranded RNA (ssRNA) molecules that guide proteins of the Argonaute (Ago) family to complementary ssRNA targets: RNA-guided RNA interference. The role of prokaryotic Ago variants has remained elusive, although bioinformatics analysis has suggested their involvement in host defence. Here we demonstrate that Ago of the bacterium Thermus thermophilus (TtAgo) acts as a barrier for the uptake and propagation of foreign DNA. In vivo, TtAgo is loaded with 5'-phosphorylated DNA guides, 13-25 nucleotides in length, that are mostly plasmid derived and have a strong bias for a 5'-end deoxycytidine. These small interfering DNAs guide TtAgo to cleave complementary DNA strands. Hence, despite structural homology to its eukaryotic counterparts, TtAgo functions in host defence by DNA-guided DNA interference
    Genome analyses of the carboxydotrophic sulfate-reducers Desulfotomaculum nigrificans and Desulfotomaculum carboxydivorans and reclassification of Desulfotomaculum caboxydivorans as a later synonym of Desulfotomaculum nigrificans
    Visser, M. ; Parshina, S.N. ; Alves, J.I. ; Sousa, D.Z. ; Pereira, I.A.C. ; Muyzer, G. ; Kuever, J. ; Lebedinsky, A.V. ; Koehorst, J.J. ; Worm, P. ; Plugge, C.M. ; Schaap, P.J. ; Goodwin, L.A. ; Lapidus, A. ; Kyrpides, N.C. ; Detter, J.C. ; Woyke, T. ; Chain, P. ; Davenport, K.W. ; Spring, S. ; Rohde, M. ; Klenk, H.P. ; Stams, A.J.M. - \ 2014
    Standards in Genomic Sciences 9 (2014)3. - ISSN 1944-3277 - p. 655 - 675.
    reducing bacterium - sp nov. - sequence - growth - classification - hydrogenase - evolution - standard - archaea - system
    Desulfotomaculum nigrificans and D. carboxydivorans are moderately thermophilic members of the polyphyletic spore-forming genus Desulfotomaculum in the family Peptococcaceae. They are phylogenetically very closely related and belong to ‘subgroup a’ of the Desulfotomaculum cluster 1. D. nigrificans and D. carboxydivorans have a similar growth substrate spectrum; they can grow with glucose and fructose as electron donors in the presence of sulfate. Additionally, both species are able to ferment fructose, although fermentation of glucose is only reported for D. carboxydivorans. D. nigrificans is able to grow with 20% carbon monoxide (CO) coupled to sulfate reduction, while D. carboxydivorans can grow at 100% CO with and without sulfate. Hydrogen is produced during growth with CO by D. carboxydivorans. Here we present a summary of the features of D. nigrificans and D. carboxydivorans together with the description of the complete genome sequencing and annotation of both strains. Moreover, we compared the genomes of both strains to reveal their differences. This comparison led us to propose a reclassification of D. carboxydivorans as a later heterotypic synonym of D. nigrificans
    High-resolution mapping of the barley Ryd3 locus controlling tolerance to BYDV
    Lüpken, T. ; Stein, N. ; Perovic, D. ; Habekuss, A. ; Serfling, A. ; Krämer, I. ; Hähnel, U. ; Steuernagel, B. ; Scholz, U. ; Ariyadasa, R. ; Martis, M. ; Mayer, K. ; Niks, R.E. ; Collins, N.C. ; Friedt, W. ; Ordon, F. - \ 2014
    Molecular Breeding 33 (2014)2. - ISSN 1380-3743 - p. 477 - 488.
    yellow-dwarf-virus - hordeum-vulgare l. - recessive bymovirus resistance - leaf rust resistance - comparative genomics - consensus map - winter barley - linkage map - yd2 gene - sequence
    Barley yellow dwarf disease (BYD) is transmitted by aphids and is caused by different strains of Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV). Economically it is one of the most important diseases of cereals worldwide. Besides chemical control of the vector, growing of tolerant/resistant cultivars is an effective way of protecting crops against BYD. The Ryd3 gene in barley (Hordeum vulgare L.) confers tolerance to BYDV-PAV and BYDV-MAV and the locus was previously mapped on the short arm of barley chromosome 6H near the centromere. We applied a strategy for high-resolution mapping and marker saturation at the Ryd3 locus by exploiting recent genomic tools available in barley. In a population of 3,210 F2 plants, 14 tightly linked markers were identified, including 10 that co-segregated with Ryd3. The centromeric region where Ryd3 is located suffers suppressed recombination or reduced recombination rate, suggesting potential problems in achieving (1) map-based cloning of Ryd3 and (2) marker selection of the resistance in breeding programmes without the introduction of undesirable traits via linkage drag.
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