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Search Results: 1 - 10 of 28 matches for " Marnik Vuylsteke "
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Linkage Mapping Identifies the Sex Determining Region as a Single Locus in the Pennate Diatom Seminavis robusta
Ives Vanstechelman, Koen Sabbe, Wim Vyverman, Pieter Vanormelingen, Marnik Vuylsteke
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060132
Abstract: The pennate diatom Seminavis robusta, characterized by an archetypical diatom life cycle including a heterothallic mating system, is emerging as a model system for studying the molecular regulation of the diatom cell and life cycle. One of its main advantages compared with other diatom model systems is that sexual crosses can be made routinely, offering unprecedented possibilities for forward genetics. To date, nothing is known about the genetic basis of sex determination in diatoms. Here, we report on the construction of mating type-specific linkage maps for S. robusta, and use them to identify a single locus sex determination system in this diatom. We identified 13 mating type plus and 15 mating type minus linkage groups obtained from the analysis of 463 AFLP markers segregating in a full-sib family, covering 963.7 and 972.2 cM, respectively. Five linkage group pairs could be identified as putative homologues. The mating type phenotype mapped as a monogenic trait, disclosing the mating type plus as the heterogametic sex. This study provides the first evidence for a genetic sex determining mechanism in a diatom.
A first AFLP-Based Genetic Linkage Map for Brine Shrimp Artemia franciscana and Its Application in Mapping the Sex Locus
Stephanie De Vos, Peter Bossier, Gilbert Van Stappen, Ilse Vercauteren, Patrick Sorgeloos, Marnik Vuylsteke
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057585
Abstract: We report on the construction of sex-specific linkage maps, the identification of sex-linked markers and the genome size estimation for the brine shrimp Artemia franciscana. Overall, from the analysis of 433 AFLP markers segregating in a 112 full-sib family we identified 21 male and 22 female linkage groups (2n = 42), covering 1,041 and 1,313 cM respectively. Fifteen putatively homologous linkage groups, including the sex linkage groups, were identified between the female and male linkage map. Eight sex-linked AFLP marker alleles were inherited from the female parent, supporting the hypothesis of a WZ–ZZ sex-determining system. The haploid Artemia genome size was estimated to 0.93 Gb by flow cytometry. The produced Artemia linkage maps provide the basis for further fine mapping and exploring of the sex-determining region and are a possible marker resource for mapping genomic loci underlying phenotypic differences among Artemia species.
At-TAX: a whole genome tiling array resource for developmental expression analysis and transcript identification in Arabidopsis thaliana
Sascha Laubinger, Georg Zeller, Stefan R Henz, Timo Sachsenberg, Christian K Widmer, Na?ra Naouar, Marnik Vuylsteke, Bernhard Sch?lkopf, Gunnar R?tsch, Detlef Weigel
Genome Biology , 2008, DOI: 10.1186/gb-2008-9-7-r112
Abstract: The generation of genome-wide gene expression data for the reference plant Arabidopsis thaliana yielded important insights into transcriptional control of development, with genome-wide expression maps having become an indispensable tool for the research community. Specific gene expression profiles for various plant organs, developmental stages, growth conditions, treatments, mutants, or even single cell types are available (for example [1-7]). These data have helped to elucidate transcriptional networks and attending promoter motifs, to uncover gene functions, and to reveal molecular explanations for mutant phenotypes (for review [8]).The most widely used platform for Arabidopsis is the Affymetrix ATH1 array [9,10]. Its design used prior information in the form of experimentally confirmed transcripts and gene predictions, and was intended to provide information on most known transcripts. Although the ATH1 array includes more than 22,500 probe sets, it lacks almost one-third of the 32,041 genes found in the most recent TAIR7 annotation [11]. All users of ATH1 arrays are confronted with a problem; as the number of newly discovered genes is rising, expression analysis becomes more and more restricted.More unbiased detection of transcriptional activity can be achieved by sequencing techniques such as massively parallel signature sequencing and serial analysis of gene expression or, alternatively, by microarrays that interrogate the entire genomic sequence, so called 'whole genome tiling arrays' [12-14]. In contrast to arrays that are focused on gene expression, which contain only probes complementary to annotated genes, whole-genome tiling arrays are designed irrespectively of gene annotations and contain probes that are regularly spaced throughout the nonrepetitive portion of the genome [15]. This includes intergenic and intronic regions, and whole-genome tiling arrays can therefore measure transcription from annotated genes, identify new splice and transcript variants
Transcriptional analysis of cell growth and morphogenesis in the unicellular green alga Micrasterias (Streptophyta), with emphasis on the role of expansin
Katrijn Vannerum, Marie JJ Huysman, Riet De Rycke, Marnik Vuylsteke, Frederik Leliaert, Jacob Pollier, Ursula Lütz-Meindl, Jeroen Gillard, Lieven De Veylder, Alain Goossens, Dirk Inzé, Wim Vyverman
BMC Plant Biology , 2011, DOI: 10.1186/1471-2229-11-128
Abstract: Genome-wide transcript expression profiling of synchronously growing cells identified 107 genes of which the expression correlated with the growth phase. Four transcripts showed high similarity to expansins that had not been examined previously in green algae. Phylogenetic analysis suggests that these genes are most closely related to the plant EXPANSIN A family, although their domain organization is very divergent. A GFP-tagged version of the expansin-resembling protein MdEXP2 localized to the cell wall and in Golgi-derived vesicles. Overexpression phenotypes ranged from lobe elongation to loss of growth polarity and planarity. These results indicate that MdEXP2 can alter the cell wall structure and, thus, might have a function related to that of land plant expansins during cell morphogenesis.Our study demonstrates the potential of M. denticulata as a unicellular model system, in which cell growth mechanisms have been discovered similar to those in land plants. Additionally, evidence is provided that the evolutionary origins of many cell wall components and regulatory genes in embryophytes precede the colonization of land.Although the form and function of plant cells are strongly correlated, the processes that determine the cell shape remain largely unknown. Plant cell morphogenesis is regulated in a non-cell-autonomous fashion by the surrounding tissues [1], hormone interference during ontogenesis, and sometimes by polyploidy as a consequence of endoreduplication [2,3]. In contrast, in unicellular relatives of land plants, it is possible to study the endogenous controls of cell morphogenesis without the interference by interacting cells and to better understand how these mechanisms have evolved in the green lineage.The desmid Micrasterias denticulata is a member of the conjugating green algae (Zygnematophyceae) that comprise the closest extant unicellular relatives of land plants [4-8]. M. denticulata cells consist of two bilaterally symmetrical flat semicells, no
Bayesian Data Fusion (BDF) of Monitoring Data with a Statistical Groundwater Contamination Model to Map Groundwater Quality at the Regional Scale  [PDF]
Samuel Mattern, Walid Raouafi, Patrick Bogaert, Dominique Fasbender, Marnik Vanclooster
Journal of Water Resource and Protection (JWARP) , 2012, DOI: 10.4236/jwarp.2012.411109
Abstract: Groundwater contamination by nitrate within an unconfined sandy aquifer was mapped using a Bayesian Data Fusion (BDF) framework. Groundwater monitoring data was therefore combined with a statistical groundwater contamination model. In a first step, nitrate concentrations, measured at 99 monitoring stations irregularly distributed within the study area, were spatialized using ordinary kriging. Secondly, a statistical regression tree model of nitrate contamination in groundwater was constructed using land use, depth to the water table, altitude and slope as predictor variables. This allowed the construction of a regression tree based contamination map. In a third step, BDF was used to combine optimally the kriged nitrate contamination map with the regression tree based model into one single map, thereby weighing the kriged and regression tree based contamination maps in terms of their estimation uncertainty. It is shown that BDF allows integrating different sources of information about contamination in a final map, allowing quantifying the expected value and variance of the nitrate contamination estimation. It is also shown that the uncertainty in the final map is smaller than the uncertainty from the kriged or regression tree based contamination map.
Cardiac tamponade and clinical acumen
Wijesuriya Shanelle,Vuylsteke Alain
Annals of Cardiac Anaesthesia , 2011,
Evaluating AVAHAN’s design, implementation and impact: lessons learned for the HIV Prevention Community
Laga Marie,Vuylsteke Bea
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-s6-s16
Perioperative melatonin secretion in patients undergoing coronary artery bypass graft surgery: a pilot study
X Guo, E Kuzumi, A Vuylsteke
Critical Care , 2001, DOI: 10.1186/cc979
Abstract: After local ethics committee approval and informed consent, 11 male patients aged between 60 and 78 years, who were scheduled for elective coronary artery bypass graft surgery under hypothermic cardiopulmonary bypass, were enrolled in the study. All patients received the same anaesthesia regimen, which is used routinely at Papworth Hospital. Blood samples for measurements of melatonin were taken during the day of surgery at specific time points and every 3 h on postoperative days 2 and 3. Plasma concentrations of melatonin were measured using a radioimmunoassay method.During surgery melatonin levels were below the minimum sensitivity level in most patients, but low levels, without circadian variation, were measured during the first postoperative night in some patients (n = 7; Fig. 1). Circadian secretion was observed on the third postoperative night, irrespective of whether the patient was on the ward (n = 6) or in the intensive care unit (ICU; n = 3; Fig. 1). However, the peak level of melatonin was observed 3 h later in patients who remained in the ICU (Fig. 1).Melatonin secretion is impaired during cardiac surgery and in the immediate postoperative period. However, a circadian rhythm is present from postoperative day 2. The clinical implication of this observation has to be evaluated further.X Guo is sponsored by the Royal Society Fellowship.
Sustainability of programs to reach high risk and marginalized populations living with HIV in resource limited settings: implications for HIV treatment and prevention
Brian T Montague, Bea Vuylsteke, Anne Buvé
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-701
Abstract: When the first programs providing access to antiretroviral treatment were launched in Africa in the early years of the 21st century, they were met with a lot of skepticism. There were concerns about the costs and the feasibility, and about adherence. The experiences of the past 10 years have shown that it is feasible to treat HIV infected patients with ART even in severely resource constrained settings, and that immunological reconstitution and virological suppression can be achieved for large numbers of patients resulting in declines in mortality [1]. Nonetheless there are still huge challenges ahead. In surveillance data from the World Health Organization in 2009, antiretroviral coverage according to 2006 guidelines with a CD4 cell count threshold of < = 200 was 52% worldwide. Coverage based on the higher 2010 threshold of CD4 count < = 350 was only 36%. Only 8 low or middle income countries have been able to achieve ART coverage rates of greater than or equal to 80% [2]. A substantial portion of HIV care has been subsidized through contributions from programs such as the US President's Emergency Plan for AIDS Relief (PEPFAR) and the Global Fund and it is unclear whether the present level of funding will be maintained, let alone increased.In the context of limited and at times declining funding for antiretroviral therapy (ART), ART programs targeting marginalized and difficult to reach populations such as female sex workers (FSW), may not be considered a priority. Concerns about feasibility and adherence in ART programs for FSW resonate with the skepticism that was voiced 10 years ago about ART programs in low resource settings. ART programs for FSW indeed do face a number of challenges. FSW are hard to reach and tend to be mobile; and adhering to a strict treatment regimen may be difficult for them because of the nature of their work and their lifestyles. The question is whether these barriers can be overcome. The study by Huet et al. demonstrates that it is poss
Perspectives on the application of biotechnology to assist the genetic enhancement of plantain and banana (Musa spp.)
Crouch,Jonathan H.; Vuylsteke,Dirk; Ortiz,Rodomiro;
Electronic Journal of Biotechnology , 1998,
Abstract: bananas and plantains (musa spp.) are the most important tropical fruit crops. they form an integral component of the farming systems in the humid agroecological zones of the tropics. a broad array of applied cell and molecular techniques are increasingly being used worldwide to facilitate and enhance the handling and improvement of plantain and banana germplasm. tissue culture is used for germplasm exchange, conservation and rapid multiplication, while in vitro seed germination (based on embryo culture or rescue) plays a critical role in generating hybrid plants. dna marker systems have been developed in musa to assist germplasm management, selection within the breeding pool or gene introgression from wild species, and for disease diagnosis. likewise, genetic transformation using the particle gun method or through agrobacterium co-cultivation shows potential for the genetic betterment of the crop. this article discusses the applications of biotechnology for the genetic enhancement of banana and plantain. it highlights current advances by research teams across the world and reviews progress in molecular breeding of musa by the international institute of tropical agriculture and its collaborators
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