41 results on '"ten Hoopen R"'
Search Results
2. Organ Donation After Euthanasia: A Pure Act of Altruism Fulfilling the Patientʼs Last Wish
- Author
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Bollen, J., de Jongh, W., Hagenaars, H., van Dijk, G., ten Hoopen, R., Ysebaert, D., IJzermans, J., van Heurn, E., and van Mook, W.
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- 2017
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3. Composition and formation of heterochromatin in Arabidopsis thaliana
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Fransz, P., ten Hoopen, R., and Tessadori, F.
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- 2006
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4. Characterisation of the nucleolar organising regions during the cell cycle in two varieties of Petunia hybrida as visualised by fluorescence in situ hybridisation and silver staining
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Montijn, M. B., ten Hoopen, R., Fransz, P. F., Oud, J. L., and Nanninga, N.
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- 1998
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5. Aansprakelijkheid voor het laten werken met chroom-6: Onderzoeksrapport WP9 als onderdeel van het Gezondheidsonderzoek gebruik gevaarlijke stoffen bij Defensie; POMS, Chroom-6 en CARC (Liability in Relation to Working with Chrome-6)
- Author
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Gundt, N, ten Hoopen, R, Meurkens, L, Philipsen, Niels, and Law and Economics
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- 2018
6. Organ Donation After Euthanasia: A Pure Act of Altruism Fulfilling the Patient's Last Wish
- Author
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Bollen, J, de Jongh, W, Hagenaars, JAM, Dijk, Gert, ten Hoopen, R, Ysebaert, D, IJzermans, J.N.M., van Heurn, E, van Mook, W, Bollen, J, de Jongh, W, Hagenaars, JAM, Dijk, Gert, ten Hoopen, R, Ysebaert, D, IJzermans, J.N.M., van Heurn, E, and van Mook, W
- Published
- 2017
7. Erratum to: The Healthy Primary School of the Future: study protocol of a quasi-experimental study
- Author
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Willeboordse, M., primary, Jansen, M. W., additional, van den Heijkant, S. N., additional, Simons, A., additional, Winkens, B., additional, de Groot, R. H. M., additional, Bartelink, N., additional, Kremers, S. P., additional, van Assema, P., additional, Savelberg, H. H., additional, de Neubourg, E., additional, Borghans, L., additional, Schils, T., additional, Coppens, K. M., additional, Dietvorst, R., additional, ten Hoopen, R., additional, Coomans, F., additional, Klosse, S., additional, Conjaerts, M. H. J., additional, Oosterhoff, M., additional, Joore, M. A., additional, Ferreira, I., additional, Muris, P., additional, Bosma, H., additional, Toppenberg, H. L., additional, and van Schayck, C. P., additional
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- 2017
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8. The Healthy Primary School of the Future: study protocol of a quasi-experimental study
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Willeboordse, M, Willeboordse, M, Jansen, M W, van den Heijkant, S N, Simons, A, Winkens, B, de Groot, R H M, Bartelink, N, Kremers, S P, van Assema, P, Savelberg, H H, de Neubourg, E, Borghans, Lex, Schils, T, Coppens, K M, Dietvorst, R, Ten Hoopen, R, Coomans, F, Klosse, S, Conjaerts, M H J, Oosterhoff, M, Joore, M A, Ferreira, I, Muris, P, Bosma, H, Toppenberg, H L, van Schayck, C P, Willeboordse, M, Willeboordse, M, Jansen, M W, van den Heijkant, S N, Simons, A, Winkens, B, de Groot, R H M, Bartelink, N, Kremers, S P, van Assema, P, Savelberg, H H, de Neubourg, E, Borghans, Lex, Schils, T, Coppens, K M, Dietvorst, R, Ten Hoopen, R, Coomans, F, Klosse, S, Conjaerts, M H J, Oosterhoff, M, Joore, M A, Ferreira, I, Muris, P, Bosma, H, Toppenberg, H L, and van Schayck, C P
- Abstract
BACKGROUND: Unhealthy lifestyles in early childhood are a major global health challenge. These lifestyles often persist from generation to generation and contribute to a vicious cycle of health-related and social problems. This design article presents a study evaluating the effects of two novel healthy school interventions. The main outcome measure will be changes in children's body mass index (BMI). In addition, lifestyle behaviours, academic achievement, child well-being, socio-economic differences, and societal costs will be examined.METHODS: In close collaboration with various stakeholders, a quasi-experimental study was developed, for which children of four intervention schools (n = 1200) in the southern part of the Netherlands are compared with children of four control schools (n = 1200) in the same region. The interventions started in November 2015. In two of the four intervention schools, a whole-school approach named 'The Healthy Primary School of the Future', is implemented with the aim of improving physical activity and dietary behaviour. For this intervention, pupils are offered an extended curriculum, including a healthy lunch, more physical exercises, and social and educational activities, next to the regular school curriculum. In the two other intervention schools, a physical-activity school approach called 'The Physical Activity School', is implemented, which is essentially similar to the other intervention, except that no lunch is provided. The interventions proceed during a period of 4 years. Apart from the effectiveness of both interventions, the process, the cost-effectiveness, and the expected legal implications are studied. Data collection is conducted within the school system. The baseline measurements started in September 2015 and yearly follow-up measurements are taking place until 2019.DISCUSSION: A whole-school approach is a new concept in the Netherlands. Due to its innovative, multifaceted nature and sound scientific fou
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- 2016
9. The Healthy Primary School of the Future: study protocol of a quasi-experimental study
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Willeboordse, M., primary, Jansen, M. W., additional, van den Heijkant, S. N., additional, Simons, A., additional, Winkens, B., additional, de Groot, R.H.M., additional, Bartelink, N., additional, Kremers, S. P., additional, van Assema, P., additional, Savelberg, H. H., additional, de Neubourg, E., additional, Borghans, L., additional, Schils, T., additional, Coppens, K. M., additional, Dietvorst, R., additional, ten Hoopen, R., additional, Coomans, F., additional, Klosse, S., additional, Conjaerts, M.H.J., additional, Oosterhoff, M., additional, Joore, M. A., additional, Ferreira, I., additional, Muris, P., additional, Bosma, H., additional, Toppenberg, H. L., additional, and van Schayck, C. P., additional
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- 2016
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10. Evolutionary conservation of kinetochore protein sequences in plants
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ten Hoopen R, Renate Manteuffel, Malysheva L, Ingo Schubert, and Jaroslav Dolezel
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Genetics ,DNA, Complementary ,Base Sequence ,Sequence Homology, Amino Acid ,Kinetochore ,Molecular Sequence Data ,CENPF ,food and beverages ,Hordeum ,Biology ,Zea mays ,Conserved sequence ,Vicia faba ,Evolution, Molecular ,biology.protein ,Homologous chromosome ,Hordeum vulgare ,Amino Acid Sequence ,Kinetochores ,Metaphase ,Mitosis ,Genetics (clinical) ,DNA Primers ,Plant Proteins - Abstract
The evolutionary conservation of structural/functional kinetochore proteins has been studied on isolated nuclei and pro-/metaphase chromosomes of mono- and dicot plants. The cross-reactivities of antibodies against human CENPC, CENPE and CENPF, and against maize CENPCa with the centromeric regions of mitotic chromosomes of Vicia faba and/or Hordeum vulgare are shown. Putative homologs of the kinetochore protein SKP1 (suppressor of kinetochore protein 1p of yeast) were found in both species and of CBF5p (centromere binding factor 5 of yeast) in barley. Antibodies against synthetic peptides derived from partial sequences encoding these proteins were produced and recognized the centromeric regions on mitotic chromosomes as detected by indirect immunofluorescence.
- Published
- 2001
11. The 5S rRNA gene clusters have a defined orientation toward the nucleolus in Petunia hybrida and Crepis capillaris
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Montijn, M., Houtsmuller, A., ten Hoopen, R., Oud, J.L., Nanninga, N., Amstel Institute (FNWI), and Molecular Cytology (SILS, FNWI)
- Published
- 1999
12. Chromosomal mapping and spatial localization of transgenes in Petunia hybrida
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ten Hoopen, R., Nanninga, Nanne, Oud, J.L., Gerats, A.G.M., and Molecular Cytology (SILS, FNWI)
- Published
- 1998
13. FISH of T-DNA on metaphase preparations reveals non-uniform recombination in Petunia hybrida
- Author
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ten Hoopen, R., Fransz, P.F., Montijn, M., Oud, J.L., Gerats, A.G.M., Robbins, T.P., Nanninga, N., and Molecular Cytology (SILS, FNWI)
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- 1995
14. Nuclear kinetics in Petunia hybrida cultivar Mitchell visualized by silver staining and FISH
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Montijn, M., ten Hoopen, R., Oud, J.L., Nanninga, N., and Molecular Cytology (SILS, FNWI)
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- 1995
15. Localization of T-DNA Insertions in Petunia by Fluorescence in Situ Hybridization: Physical Evidence for Suppression of Recombination.
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Ten Hoopen, R., primary, Robbins, T. P., additional, Fransz, P. F., additional, Montijn, B. M., additional, Oud, O., additional, Gerats, AGM., additional, and Nanninga, N., additional
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- 1996
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16. Preferential MGMT hypermethylation in SDH-deficient wild-type GIST.
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Giger OT, Ten Hoopen R, Shorthouse D, Abdullahi S, Bulusu VR, Jadhav S, Maher ER, and Casey RT
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- Humans, DNA Methylation, Epigenesis, Genetic, Mutation, Protein-Tyrosine Kinases genetics, DNA Repair Enzymes genetics, DNA Repair Enzymes metabolism, DNA Modification Methylases genetics, Tumor Suppressor Proteins genetics, Tumor Suppressor Proteins metabolism, Succinate Dehydrogenase, Gastrointestinal Stromal Tumors genetics, Gastrointestinal Stromal Tumors pathology
- Abstract
Aims: Wild-type gastrointestinal stromal tumours (wtGIST) are frequently caused by inherited pathogenic variants, or somatic alterations in the succinate dehydrogenase subunit genes ( SDHx ). Succinate dehydrogenase is a key enzyme in the citric acid cycle. SDH deficiency caused by SDHx inactivation leads to an accumulation of succinate, which inhibits DNA and histone demethylase enzymes, resulting in global hypermethylation. Epigenetic silencing of the DNA repair gene MGMT has proven utility as a positive predictor of the therapeutic efficacy of the alklyating drug temozolomide (TMZ) in tumours such as glioblastoma multiforme. The aim of this study was to examine MGMT promoter methylation status in a large cohort of GIST., Methods: MGMT methylation analysis was performed on 65 tumour samples including 47 wtGIST (33 SDH-deficient wtGIST and 11 SDH preserved wtGIST) and 21 tyrosine kinase (TK) mutant GIST., Results: MGMT promoter methylation was detected in 8 cases of SDH-deficient (dSDH) GIST but in none of the 14 SDH preserved wild-type GIST or 21 TK mutant GIST samples analysed. Mean MGMT methylation was significantly higher (p 0.0449) and MGMT expression significantly lower (p<0.0001) in dSDH wtGIST compared with TK mutant or SDH preserved GIST. No correlation was identified between SDHx subunit gene mutations or SDHC epimutation status and mean MGMT methylation levels., Conclusion: MGMT promoter hypermethylation occurs exclusively in a subset of dSDH wtGIST. Data from this study support testing of tumour MGMT promoter methylation in patients with dSDH wtGIST to identify those patients who may benefit from most from TMZ therapy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)
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- 2023
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17. Organ donation after euthanasia in a patient living with dementia: a landmark case report.
- Author
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van Dijk N, Vliegen F, Ham A, de Jongh W, Berkhout FJ, Blankevoort J, Ten Hoopen R, Bollen J, and van Mook W
- Abstract
Background: Organ donation after euthanasia (ODE) has been performed over 100 times in the Netherlands, primarily involving patients suffering from a neurodegenerative or psychiatric disease. In recent years, the number of euthanasia cases related to dementia has increased in the Netherlands, with some patients living with dementia expressing a wish for organ donation after euthanasia., Methods: We describe a unique case of a 67-year-old female diagnosed with primary progressive aphasia as part of frontotemporal dementia who requested and underwent organ donation after euthanasia., Results: The patient had expressed her explicit wishes for both euthanasia and organ donation, which were discussed with her family physician, the Euthanasia Expertise Center (EE), and an organ donation coordinator. The patient was informed that to proceed with ODE, she should still be capable of voicing a voluntary and well-considered request for organ donation. The legally required euthanasia assessment procedure was carefully completed before ODE. Multiple healthcare professionals assessed the patient's competence, voluntariness, and unbearable suffering. Thereafter the patient's ODE request was granted, and both lungs and kidneys were successfully donated and transplanted. Post hoc analysis confirmed that all due diligence criteria for euthanasia were met, and the patient's relatives received an anonymous letter of gratitude from one of the organ recipients., Conclusions: This unique case demonstrates that ODE is feasible from medical, ethical, and legal perspectives in patients living with dementia. This case highlights several aspects essential to enable an ODE request by a patient living with dementia to be granted, such as the role of the physician performing euthanasia, the relevance of the decision-making capacity of the patient, the presence of an advance directive, and the involvement of and support by relatives and caregivers. However, several unresolved ethical issues surrounding ODE in patients with dementia, especially in patients with advanced stages of dementia, warrant further exploration, including the timing of discussing organ donation after the initial euthanasia request., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 van Dijk, Vliegen, Ham, de Jongh, Berkhout, Blankevoort, ten Hoopen, Bollen and van Mook.)
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- 2023
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18. Inherited MUTYH mutations cause elevated somatic mutation rates and distinctive mutational signatures in normal human cells.
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Robinson PS, Thomas LE, Abascal F, Jung H, Harvey LMR, West HD, Olafsson S, Lee BCH, Coorens THH, Lee-Six H, Butlin L, Lander N, Truscott R, Sanders MA, Lensing SV, Buczacki SJA, Ten Hoopen R, Coleman N, Brunton-Sim R, Rushbrook S, Saeb-Parsy K, Lalloo F, Campbell PJ, Martincorena I, Sampson JR, and Stratton MR
- Subjects
- DNA Glycosylases metabolism, Genetic Predisposition to Disease, Germ-Line Mutation, Humans, Mutation, Mutation Rate, Adenomatous Polyposis Coli genetics, Adenomatous Polyposis Coli pathology, Colorectal Neoplasms genetics, Colorectal Neoplasms pathology, DNA Glycosylases genetics
- Abstract
Cellular DNA damage caused by reactive oxygen species is repaired by the base excision repair (BER) pathway which includes the DNA glycosylase MUTYH. Inherited biallelic MUTYH mutations cause predisposition to colorectal adenomas and carcinoma. However, the mechanistic progression from germline MUTYH mutations to MUTYH-Associated Polyposis (MAP) is incompletely understood. Here, we sequence normal tissue DNAs from 10 individuals with MAP. Somatic base substitution mutation rates in intestinal epithelial cells were elevated 2 to 4-fold in all individuals, except for one showing a 31-fold increase, and were also increased in other tissues. The increased mutation burdens were of multiple mutational signatures characterised by C > A changes. Different mutation rates and signatures between individuals are likely due to different MUTYH mutations or additional inherited mutations in other BER pathway genes. The elevated base substitution rate in normal cells likely accounts for the predisposition to neoplasia in MAP. Despite ubiquitously elevated mutation rates, individuals with MAP do not display overt evidence of premature ageing. Thus, accumulation of somatic mutations may not be sufficient to cause the global organismal functional decline of ageing., (© 2022. The Author(s).)
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- 2022
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19. A Diffusion-like Process Accommodates New Crypts During Clonal Expansion in Human Colonic Epithelium.
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Olpe C, Khamis D, Chukanova M, Skoufou-Papoutsaki N, Kemp R, Marks K, Tatton C, Lindskog C, Nicholson A, Brunton-Sim R, Malhotra S, Ten Hoopen R, Stanley R, Winton DJ, and Morrissey E
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- Adolescent, Adult, Age Factors, Aged, Aged, 80 and over, Cell Transformation, Neoplastic metabolism, Cell Transformation, Neoplastic pathology, Colonic Polyps metabolism, Colonic Polyps pathology, Colorectal Neoplasms metabolism, Colorectal Neoplasms pathology, Diffusion, Epithelial Cells metabolism, Female, Histone Demethylases metabolism, Humans, Intestinal Mucosa metabolism, Male, Middle Aged, Models, Biological, Neoplastic Stem Cells metabolism, Proto-Oncogene Proteins p21(ras) metabolism, Young Adult, Cell Proliferation, Cell Transformation, Neoplastic genetics, Colonic Polyps genetics, Colorectal Neoplasms genetics, Epithelial Cells pathology, Histone Demethylases genetics, Intestinal Mucosa pathology, Mutation, Neoplastic Stem Cells pathology, Proto-Oncogene Proteins p21(ras) genetics
- Abstract
Background & Aims: Colorectal cancer (CRC) is thought to arise when the cumulative mutational burden within colonic crypts exceeds a certain threshold that leads to clonal expansion and ultimately neoplastic transformation. Therefore, quantification of the fixation and subsequent expansion of somatic mutations in normal epithelium is key to understanding colorectal cancer initiation. The aim of the present study was to determine how advantaged expansions can be accommodated in the human colon., Methods: Immunohistochemistry was used to visualize loss of the cancer driver KDM6A in formalin-fixed paraffin-embedded (FFPE) normal human colonic epithelium. Combining microscopy with neural network-based image analysis, we determined the frequencies of KDM6A-mutant crypts and fission/fusion intermediates as well as the spatial distribution of clones. Mathematical modeling then defined the dynamics of their fixation and expansion., Results: Interpretation of the age-related behavior of KDM6A-negative clones revealed significant competitive advantage in intracrypt dynamics as well as a 5-fold increase in crypt fission rate. This was not accompanied by an increase in crypt fusion. Mathematical modeling of crypt spacing identifies evidence for a crypt diffusion process. We define the threshold fission rate at which diffusion fails to accommodate new crypts, which can be exceeded by KRAS activating mutations., Conclusions: Advantaged gene mutations in KDM6A expand dramatically by crypt fission but not fusion. The crypt diffusion process enables accommodation of the additional crypts up to a threshold value, beyond which polyp growth may occur. The fission rate associated with KRAS mutations offers a potential explanation for KRAS-initiated polyps., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
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20. Next-generation sequencing demonstrates the rarity of short kinase variants specific to quadruple wild-type gastrointestinal stromal tumours.
- Author
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Wong NACS, Giger OT, Ten Hoopen R, Casey RT, Russell K, and Faulkner C
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- Adolescent, Adult, Aged, Cohort Studies, Female, Formaldehyde, Gastrointestinal Stromal Tumors classification, High-Throughput Nucleotide Sequencing, Humans, Male, Middle Aged, Paraffin Embedding, Young Adult, Gastrointestinal Stromal Tumors genetics, Genetic Variation, Phosphotransferases genetics
- Abstract
Aim: There is no known specific biomarker or genetic signal for quadruple wild-type (qWT) gastrointestinal stromal tumours (GISTs). By next-generation sequencing (NGS) of different GIST subgroups, this study aimed to characterise such a biomarker especially as a potential therapeutic target., Methods and Results: An NGS panel of 672 kinase genes was applied to DNA extracted from 11 wild-type GISTs (including three qWT GISTs) and 5 KIT/PDGFRA mutated GISTs. Short variants which were present in qWT GISTs but no other GIST subgroup were shortlisted. After removing common population variants, in silico-classified deleterious variants were found in CSNK2A1 , MERTK , RHEB , ROCK1 , PIKFYVE and TRRAP . None of these variants were demonstrated in a separate cohort of four qWT GISTs., Conclusions: Short kinase variants which are specific to qWT GISTs are rare and are not universally demonstrated by this whole subgroup. It is therefore possible that the current definition of qWT GIST still covers a heterogenous population., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2021
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21. medische coronaclaims.
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Ten Hoopen R and Zanders B
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- 2020
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22. Organ donation after euthanasia in children: Belgian and Dutch perspectives.
- Author
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Bollen JAM, Ten Hoopen R, van der Hoeven MAHBM, Shaw D, Brierley J, Ysebaert D, van Heurn LWE, and van Mook WNKA
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- Belgium epidemiology, Child, Child, Preschool, Decision Making, Euthanasia psychology, Female, Health Services Research, Humans, Male, Medical Futility legislation & jurisprudence, Netherlands epidemiology, Personal Autonomy, Terminal Care ethics, Tissue and Organ Procurement ethics, Euthanasia legislation & jurisprudence, Medical Futility psychology, Mental Competency legislation & jurisprudence, Terminal Care psychology, Tissue Donors psychology, Tissue and Organ Procurement legislation & jurisprudence
- Abstract
Competing Interests: Competing interests: None declared.
- Published
- 2019
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23. SDHC epi-mutation testing in gastrointestinal stromal tumours and related tumours in clinical practice.
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Casey RT, Ten Hoopen R, Ochoa E, Challis BG, Whitworth J, Smith PS, Martin JE, Clark GR, Rodger F, Maranian M, Allinson K, Madhu B, Roberts T, Campos L, Anstee J, Park SM, Marker A, Watts C, Bulusu VR, Giger OT, and Maher ER
- Subjects
- Adolescent, Adrenal Gland Neoplasms genetics, Adult, Aged, DNA Methylation genetics, Epigenomics methods, Female, Gastrointestinal Stromal Tumors metabolism, Genes, Regulator genetics, Germ-Line Mutation, High-Throughput Nucleotide Sequencing methods, Humans, Male, Membrane Proteins genetics, Membrane Proteins metabolism, Middle Aged, Mutation, Paraganglioma genetics, Pheochromocytoma genetics, Promoter Regions, Genetic genetics, Succinate Dehydrogenase metabolism, Transcriptome genetics, Epigenesis, Genetic genetics, Gastrointestinal Stromal Tumors genetics, Succinate Dehydrogenase genetics
- Abstract
The enzyme succinate dehydrogenase (SDH) functions in the citric acid cycle and loss of function predisposes to the development of phaeochromocytoma/paraganglioma (PPGL), wild type gastrointestinal stromal tumour (wtGIST) and renal cell carcinoma. SDH-deficient tumours are most commonly associated with a germline SDH subunit gene (SDHA/B/C/D) mutation but can also be associated with epigenetic silencing of the SDHC gene. However, clinical diagnostic testing for an SDHC epimutation is not widely available. The objective of this study was to investigate the indications for and the optimum diagnostic pathways for the detection of SDHC epimutations in clinical practice. SDHC promoter methylation analysis of 32 paraffin embedded tumours (including 15 GIST and 17 PPGL) was performed using a pyrosequencing technique and correlated with SDHC gene expression. SDHC promoter methylation was identified in 6 (18.7%) tumours. All 6 SDHC epimutation cases presented with SDH deficient wtGIST and 3/6 cases had multiple primary tumours. No case of constitutional SDHC promoter hypermethylation was detected. Whole genome sequencing of germline DNA from three wtGIST cases with an SDHC epimutation, did not reveal any causative sequence anomalies. Herein, we recommend a diagnostic workflow for the detection of an SDHC epimutation in a service setting.
- Published
- 2019
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24. Euthanasia through living organ donation: Ethical, legal, and medical challenges.
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Bollen JAM, Shaw D, de Wert G, Ten Hoopen R, Ysebaert D, van Heurn E, and van Mook WNKA
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- Belgium, Humans, Netherlands, Tissue and Organ Procurement ethics, Warm Ischemia legislation & jurisprudence, Euthanasia legislation & jurisprudence, Living Donors ethics, Organ Transplantation legislation & jurisprudence, Tissue and Organ Procurement legislation & jurisprudence
- Abstract
Euthanasia is categorically prohibited in almost all countries throughout the world. In Belgium and the Netherlands, combining euthanasia and subsequent organ donation in a so-called donation after circulatory-death (DCD) procedure is feasible on legal and medical grounds, and is increasingly gaining social and ethical acceptance. However, heart transplantation after DCD is currently not performed in Belgium and the Netherlands after euthanasia due to concerns surrounding the prolonged warm ischemia time associated with DCD and its effect on subsequent heart function. A number of patients who undergo euthanasia explicitly express their wish to donate their organs in a "living organ donation" procedure, which then causes death. Assuming that euthanasia is permitted, as expressed in Dutch and Belgian legislation, this exploratory article addresses whether it is legally and ethically sound to donate organs, especially the heart, as a living donor and to perform euthanasia in the same procedure in a patient who fulfills the due diligence requirements for euthanasia. Organ donation euthanasia (ODE) would then cause death by the associated surgical procedure, and in addition would improve the quality of the other donated organs, a procedure that would fully respect the patient's autonomy., (Copyright © 2018 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)
- Published
- 2019
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25. Metabolite quantification of faecal extracts from colorectal cancer patients and healthy controls.
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Le Gall G, Guttula K, Kellingray L, Tett AJ, Ten Hoopen R, Kemsley EK, Savva GM, Ibrahim A, and Narbad A
- Abstract
Colorectal cancer (CRC), a primary cause of morbidity and mortality worldwide is expected to rise in the coming years. A better understanding of the metabolic changes taking place during the disease progression is needed for effective improvements of screening strategies and treatments. In the present study, Nuclear Magnetic Resonance (NMR) metabolomics was used to quantify the absolute concentrations of metabolites in faecal extracts from two cohorts of CRC patients and healthy controls. The quantification of over 80 compounds revealed that patients with CRC had increased faecal concentrations of branched chain fatty acids (BCFA), isovalerate and isobutyrate plus valerate and phenylacetate but diminished concentrations of amino acids, sugars, methanol and bile acids (deoxycholate, lithodeoxycholate and cholate). These results suggest that alterations in microbial activity and composition could have triggered an increase in utilisation of host intestinal slough cells and mucins and led to an increase in BCFA, valerate and phenylacetate. Concurrently, a general reduction in the microbial metabolic function may have led to reduced levels of other components (amino acids, sugars and bile acids) normally produced under healthy conditions. This study provides a thorough listing of the most abundant compounds found in human faecal waters and presents a template for absolute quantification of metabolites. The production of BCFA and phenylacetate in colonic carcinogenesis warrants further investigations., Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest.
- Published
- 2018
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26. Fixation and Spread of Somatic Mutations in Adult Human Colonic Epithelium.
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Nicholson AM, Olpe C, Hoyle A, Thorsen AS, Rus T, Colombé M, Brunton-Sim R, Kemp R, Marks K, Quirke P, Malhotra S, Ten Hoopen R, Ibrahim A, Lindskog C, Myers MB, Parsons B, Tavaré S, Wilkinson M, Morrissey E, and Winton DJ
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Algorithms, Alleles, Antigens, Nuclear metabolism, Cell Cycle Proteins, Child, Humans, Middle Aged, Models, Statistical, Monoamine Oxidase metabolism, Stem Cells cytology, Stem Cells metabolism, Young Adult, Antigens, Nuclear genetics, Colon cytology, Epithelial Cells metabolism, Epithelium metabolism, Monoamine Oxidase genetics, Mutation
- Abstract
We investigated the means and timing by which mutations become fixed in the human colonic epithelium by visualizing somatic clones and mathematical inference. Fixation requires two sequential steps. First, one of approximately seven active stem cells residing within each colonic crypt has to be mutated. Second, the mutated stem cell has to replace neighbors to populate the entire crypt in a process that takes several years. Subsequent clonal expansion due to crypt fission is infrequent for neutral mutations (around 0.7% of all crypts undergo fission in a single year). Pro-oncogenic mutations subvert both stem cell replacement to accelerate fixation and clonal expansion by crypt fission to achieve high mutant allele frequencies with age. The benchmarking of these behaviors allows the advantage associated with different gene-specific mutations to be compared irrespective of the cellular mechanisms by which they are conferred., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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27. Translating in vivo metabolomic analysis of succinate dehydrogenase deficient tumours into clinical utility.
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Casey RT, McLean MA, Madhu B, Challis BG, Ten Hoopen R, Roberts T, Clark GR, Pittfield D, Simpson HL, Bulusu VR, Allinson K, Happerfield L, Park SM, Marker A, Giger O, Maher ER, and Gallagher FA
- Abstract
Purpose: Mutations in the mitochondrial enzyme succinate dehydrogenase (SDH) subunit genes are associated with a wide spectrum of tumours including phaeochromocytoma and paraganglioma (PPGL) 1, 2, gastrointestinal stromal tumours (GIST) 3, renal cell carcinoma (RCC) 4 and pituitary adenomas5. SDH-related tumorigenesis is believed to be secondary to accumulation of the oncometabolite succinate. Our aim was to investigate the potential clinical applications of MRI spectroscopy (
1 H-MRS) in a range of suspected SDH-related tumours., Patients and Methods: Fifteen patients were recruited to this study. Respiratory-gated single-voxel1 H-MRS was performed at 3T to quantify the content of succinate at 2.4 ppm and choline at 3.22 ppm., Results: A succinate peak was seen in six patients, all of whom had a germline SDHx mutation or loss of SDHB by immunohistochemistry. A succinate peak was also detected in two patients with a metastatic wild-type GIST (wtGIST) and no detectable germline SDHx mutation but a somatic epimutation in SDHC. Three patients without a tumour succinate peak retained SDHB expression, consistent with SDH functionality. In six cases with a borderline or absent peak, technical difficulties such as motion artefact rendered1 H-MRS difficult to interpret. Sequential imaging in a patient with a metastatic abdominal paraganglioma demonstrated loss of the succinate peak after four cycles of [177 Lu]-DOTATATE, with a corresponding biochemical response in normetanephrine., Conclusions: This study has demonstrated the translation into clinical practice of in vivo metabolomic analysis using1 H-MRS in patients with SDH-deficient tumours. Potential applications include non-invasive diagnosis and disease stratification, as well as monitoring of tumour response to targeted treatments., Competing Interests: The authors have nothing to declare and there are no conflict of interests to report. Disclosure: The authors have declared no conflicts of interest.- Published
- 2018
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28. Potential Number of Organ Donors After Euthanasia in Belgium.
- Author
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Bollen J, van Smaalen T, Ten Hoopen R, van Heurn E, Ysebaert D, and van Mook W
- Subjects
- Age Factors, Belgium, Donor Selection standards, Guidelines as Topic, Humans, Kidney, Liver, Lung, Pancreas, Donor Selection statistics & numerical data, Euthanasia statistics & numerical data, Tissue Donors supply & distribution
- Published
- 2017
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29. Legal and ethical aspects of organ donation after euthanasia in Belgium and the Netherlands.
- Author
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Bollen J, Ten Hoopen R, Ysebaert D, van Mook W, and van Heurn E
- Subjects
- Age Factors, Attitude of Health Personnel, Belgium epidemiology, Humans, Netherlands epidemiology, Personal Autonomy, Policy Making, Public Policy, Euthanasia ethics, Euthanasia legislation & jurisprudence, Informed Consent ethics, Informed Consent legislation & jurisprudence, Tissue Donors ethics, Tissue Donors legislation & jurisprudence, Tissue and Organ Procurement ethics, Tissue and Organ Procurement legislation & jurisprudence
- Abstract
Organ donation after euthanasia has been performed more than 40 times in Belgium and the Netherlands together. Preliminary results of procedures that have been performed until now demonstrate that this leads to good medical results in the recipient of the organs. Several legal aspects could be changed to further facilitate the combination of organ donation and euthanasia. On the ethical side, several controversies remain, giving rise to an ongoing, but necessary and useful debate. Further experiences will clarify whether both procedures should be strictly separated and whether the dead donor rule should be strictly applied. Opinions still differ on whether the patient's physician should address the possibility of organ donation after euthanasia, which laws should be adapted and which preparatory acts should be performed. These and other procedural issues potentially conflict with the patient's request for organ donation or the circumstances in which euthanasia (without subsequent organ donation) traditionally occurs., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)
- Published
- 2016
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30. 5-hydroxymethylcytosine marks promoters in colon that resist DNA hypermethylation in cancer.
- Author
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Uribe-Lewis S, Stark R, Carroll T, Dunning MJ, Bachman M, Ito Y, Stojic L, Halim S, Vowler SL, Lynch AG, Delatte B, de Bony EJ, Colin L, Defrance M, Krueger F, Silva AL, Ten Hoopen R, Ibrahim AE, Fuks F, and Murrell A
- Subjects
- 5-Methylcytosine analogs & derivatives, Cell Proliferation genetics, Colonic Neoplasms pathology, Cytosine metabolism, DNA-Binding Proteins genetics, Dioxygenases, Gene Expression Regulation, Neoplastic, HCT116 Cells, Humans, Proto-Oncogene Proteins genetics, Colonic Neoplasms genetics, Cytosine analogs & derivatives, DNA Methylation genetics, DNA-Binding Proteins biosynthesis, Proto-Oncogene Proteins biosynthesis
- Abstract
Background: The discovery of cytosine hydroxymethylation (5hmC) as a mechanism that potentially controls DNA methylation changes typical of neoplasia prompted us to investigate its behaviour in colon cancer. 5hmC is globally reduced in proliferating cells such as colon tumours and the gut crypt progenitors, from which tumours can arise., Results: Here, we show that colorectal tumours and cancer cells express Ten-Eleven-Translocation (TET) transcripts at levels similar to normal tissues. Genome-wide analyses show that promoters marked by 5hmC in normal tissue, and those identified as TET2 targets in colorectal cancer cells, are resistant to methylation gain in cancer. In vitro studies of TET2 in cancer cells confirm that these promoters are resistant to methylation gain independently of sustained TET2 expression. We also find that a considerable number of the methylation gain-resistant promoters marked by 5hmC in normal colon overlap with those that are marked with poised bivalent histone modifications in embryonic stem cells., Conclusions: Together our results indicate that promoters that acquire 5hmC upon normal colon differentiation are innately resistant to neoplastic hypermethylation by mechanisms that do not require high levels of 5hmC in tumours. Our study highlights the potential of cytosine modifications as biomarkers of cancerous cell proliferation.
- Published
- 2015
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31. Spindle pole body history intrinsically links pole identity with asymmetric fate in budding yeast.
- Author
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Juanes MA, Twyman H, Tunnacliffe E, Guo Z, ten Hoopen R, and Segal M
- Subjects
- Cell Division, Cytoskeletal Proteins genetics, Cytoskeletal Proteins metabolism, Microtubule-Associated Proteins genetics, Microtubule-Associated Proteins metabolism, Nuclear Proteins genetics, Nuclear Proteins metabolism, Polymerase Chain Reaction, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism, Tubulin genetics, Tubulin metabolism, Microtubules metabolism, Saccharomyces cerevisiae cytology, Saccharomyces cerevisiae genetics, Spindle Poles metabolism
- Abstract
Background: Budding yeast is a unique model for exploring differential fate in a cell dividing asymmetrically. In yeast, spindle orientation begins with the old spindle pole body (SPB) (from the preceding cell cycle) contacting the bud by its existing astral microtubules (aMTs) while the new pole delays astral microtubule organization. This appears to prime the inheritance of the old pole by the bud. The basis for this asymmetry and the discrimination of the poles by virtue of their history remain a mystery., Results: Here, we report that asymmetric aMT organization stems from an outstanding structural asymmetry linked to the SPB cycle. We show that the γ-tubulin nucleation complex (γTC) favors the old spindle pole, an asymmetry inherent to the outer plaque (the cytoplasmic face of the SPB). Indeed, Spc72 (the receptor for the γTC) is acquired by the new SPB outer plaque partway through spindle assembly. The significance of this asymmetry was explored in cells expressing an Spc72(1-276)-Cnm67 fusion that forced symmetric nucleation at the SPB outer plaques. This manipulation triggered simultaneous aMT organization by both spindle poles from the outset and led to symmetric contacts between poles and the bud, effectively disrupting the program for spindle polarity. Temporally symmetric aMT organization perturbed Kar9 polarization by randomizing the choice of the pole to be guided toward the bud. Accordingly, the pattern of SPB inheritance was also randomized., Conclusions: Spc72 differential recruitment imparting asymmetric aMT organization represents the most upstream determinant linking SPB historical identity and fate., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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32. Mechanism for astral microtubule capture by cortical Bud6p priming spindle polarity in S. cerevisiae.
- Author
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Ten Hoopen R, Cepeda-García C, Fernández-Arruti R, Juanes MA, Delgehyr N, and Segal M
- Subjects
- Actins metabolism, Actins ultrastructure, Blotting, Western, Densitometry, Dyneins metabolism, Electrophoresis, Polyacrylamide Gel, Kymography, Microtubules metabolism, Saccharomyces cerevisiae metabolism, Time-Lapse Imaging, Cell Cycle Proteins metabolism, Kinesins metabolism, Microfilament Proteins metabolism, Microtubule Proteins metabolism, Microtubules physiology, Models, Molecular, Saccharomyces cerevisiae growth & development, Saccharomyces cerevisiae Proteins metabolism, Spindle Apparatus physiology
- Abstract
Background: Budding yeast is a unique model to dissect spindle orientation in a cell dividing asymmetrically. In yeast, this process begins with the capture of pole-derived astral microtubules (MTs) by the polarity determinant Bud6p at the cortex of the bud in G(1). Bud6p couples MT growth and shrinkage with spindle pole movement relative to the contact site. This activity resides in N-terminal sequences away from a domain linked to actin organization. Kip3p (kinesin-8), a MT depolymerase, may be implicated, but other molecular details are essentially unknown., Results: We show that Bud6p and Kip3p play antagonistic roles in controlling the length of MTs contacting the bud. The stabilizing role of Bud6p required the plus-end-tracking protein Bim1p (yeast EB1). Bim1p bound Bud6p N terminus, an interaction that proved essential for cortical capture of MTs in vivo. Moreover, Bud6p influenced Kip3p dynamic distribution through its effect on MT stability during cortical contacts via Bim1p. Coupling between Kip3p-driven depolymerization and shrinkage at the cell cortex required Bud6p, Bim1p, and dynein, a minus-end-directed motor helping tether the receding plus ends to the cell cortex. Validating these findings, live imaging of the interplay between dynein and Kip3p demonstrated that both motors decorated single astral MTs with dynein persisting at the plus end in association with the site of cortical contact during shrinkage at the cell cortex., Conclusions: Astral MT shrinkage linked to Bud6p involves its direct interaction with Bim1p and the concerted action of two MT motors-Kip3p and dynein., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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33. Ase1p phosphorylation by cyclin-dependent kinase promotes correct spindle assembly in S. cerevisiae.
- Author
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Juanes MA, ten Hoopen R, and Segal M
- Subjects
- Cathepsin A, Microscopy, Phosphorylation, Cyclin-Dependent Kinases metabolism, Microtubule-Associated Proteins metabolism, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Spindle Apparatus metabolism
- Abstract
Spindle morphogenesis and dynamics follow an orderly sequence of events coupled to the oscillatory activation of cyclin-dependent kinase (CDK). Using S. cerevisiae, we have addressed the requirement of CDK for phosphorylation of the spindle midzone component Ase1p and its significance to spindle assembly. Ase1p is related to human PRC1, a protein negatively regulated by CDK until late mitosis, when it is required for central spindle organization and cytokinesis. By contrast, we show here that Ase1p phosphorylation by CDK promotes correct spindle assembly. Indeed, Ase1p phosphorylation coincident with spindle assembly requires Clb5p, Clb3p and Clb4p. Moreover, in clb5Δ cells, Ase1p recruitment and the kinetics of spindle formation were perturbed. These phenotypes were enhanced in a cdc28-4 clb5Δ mutant to the extent that midzone disruption resulted in transient breaks of the short spindle. By contrast, clb3Δ clb4Δ cells delayed spindle assembly downstream to Ase1p recruitment. Expression of Ase1(7D) p that mimics the phosphorylated state restored timely recruitment in clb5Δ cells and fully rescued the corresponding spindle phenotypes. Finally, Ase1(7D) p partially suppressed the spindle assembly delay in clb3Δ clb4Δ cells. Thus, Ase1p phosphorylation by CDK promotes the assembly and stability of the mitotic spindle. It follows that CDK may differentially alter the functionality of members of the Ase1p/PRC1 family to place their distinct roles in their respective stage-specific contexts, a further factor of complexity in the organization of pathways promoting spindle assembly and dynamics.
- Published
- 2011
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34. Actin-mediated delivery of astral microtubules instructs Kar9p asymmetric loading to the bud-ward spindle pole.
- Author
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Cepeda-García C, Delgehyr N, Juanes Ortiz MA, ten Hoopen R, Zhiteneva A, and Segal M
- Subjects
- Bridged Bicyclo Compounds, Heterocyclic pharmacology, Cell Polarity drug effects, Green Fluorescent Proteins metabolism, Microtubules drug effects, Models, Biological, Mutation genetics, Nocodazole pharmacology, Protein Transport drug effects, Recombinant Fusion Proteins metabolism, Saccharomyces cerevisiae cytology, Saccharomyces cerevisiae drug effects, Spindle Apparatus drug effects, Thiazolidines pharmacology, Actins metabolism, Microtubules metabolism, Nuclear Proteins metabolism, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Spindle Apparatus metabolism
- Abstract
In Saccharomyces cerevisiae, Kar9p, one player in spindle alignment, guides the bud-ward spindle pole by linking astral microtubule plus ends to Myo2p-based transport along actin cables generated by the formins Bni1p and Bnr1p and the polarity determinant Bud6p. Initially, Kar9p labels both poles but progressively singles out the bud-ward pole. Here, we show that this polarization requires cell polarity determinants, actin cables, and microtubules. Indeed, in a bud6 Delta bni1 Delta mutant or upon direct depolymerization of actin cables Kar9p symmetry increased. Furthermore, symmetry was selectively induced by myo2 alleles, preventing Kar9p binding to the Myo2p cargo domain. Kar9p polarity was rebuilt after transient disruption of microtubules, dependent on cell polarity and actin cables. Symmetry breaking also occurred after transient depolymerization of actin cables, with Kar9p increasing at the spindle pole engaging in repeated cycles of Kar9p-mediated transport. Kar9p returning to the spindle pole on shrinking astral microtubules may contribute toward this bias. Thus, Myo2p transport along actin cables may support a feedback loop by which delivery of astral microtubule plus ends sustains Kar9p polarized recruitment to the bud-ward spindle pole. Our findings also explain the link between Kar9p polarity and the choice setting aside the old spindle pole for daughter-bound fate.
- Published
- 2010
- Full Text
- View/download PDF
35. Transient CENP-E-like kinetochore proteins in plants.
- Author
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ten Hoopen R, Schleker T, Manteuffel R, and Schubert I
- Subjects
- Amino Acid Sequence, Cell Nucleus metabolism, Centromere metabolism, Chromosomal Proteins, Non-Histone chemistry, Chromosomal Proteins, Non-Histone metabolism, Chromosomes metabolism, Conserved Sequence, Escherichia coli genetics, Hordeum genetics, Humans, Lymphocytes metabolism, Meristem cytology, Meristem metabolism, Mitosis, Molecular Sequence Data, Recombinant Proteins isolation & purification, Recombinant Proteins metabolism, Sequence Homology, Amino Acid, Vicia genetics, Chromosomal Proteins, Non-Histone genetics, Kinetochores metabolism, Plant Proteins genetics
- Abstract
Derived from candidate sequences of a barley EST database two proteins with homology to the coiled coil region of the human kinetochore protein (KP) CENP-E were generated and classified as centromere protein E-like 1 and 2 (Cpell and Cpe12). Specific antibodies produced against recombinant Cpe11 and Cpe12 proteins labeled the centromere on mitotic chromosomes of barley and field bean and recognized specifically proteins from nuclear/chromosomal protein extracts on immunoblots. No function was predicted for homologues of Cpe11 within the databases for Arabidopsis and rice genomes. However, the centromeric location of Cpe11 and Cpe12 suggests they may have a function within the kinetochore. Plant homologues to barley Cpe12 are N-type kinesins, suggesting that Cpe12 is functionally homologous to human CENP-E.
- Published
- 2002
- Full Text
- View/download PDF
36. Sequence organization of barley centromeres.
- Author
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Hudakova S, Michalek W, Presting GG, ten Hoopen R, dos Santos K, Jasencakova Z, and Schubert I
- Subjects
- Blotting, Southern, Cloning, Molecular, DNA Restriction Enzymes metabolism, DNA, Plant chemistry, DNA, Plant metabolism, In Situ Hybridization, Fluorescence, Molecular Sequence Data, Mutagenesis, Insertional, Retroelements, Sequence Analysis, DNA, Centromere genetics, DNA, Plant genetics, Hordeum genetics
- Abstract
By sequencing, fingerprinting and in situ hybridization of a centromere-specific large insert clone (BAC 7), the sequence organization of centromeric DNA of barley could be elucidated. Within 23 kb, three copies of the Ty3/gypsy-like retroelement cereba were present. Two elements of approximately 7 kb, arranged in tandem, include long terminal repeats (LTRs) (approximately 1 kb) similar to the rice centromeric retrotransposon RIRE 7 and to the cereal centromeric sequence family, the primer binding site, the complete polygene flanked by untranslated regions, as well as a polypurine tract 5' of the downstream LTR. The high density (approximately 200 elements/centromere) and completeness of cereba elements and the absence of internally deleted elements and solo LTRs from the BAC 7 insert represent unique features of the barley centromeres as compared to those of other cereals. Obviously, the conserved cereba elements together with barley-specific G+C-rich satellite sequences constitute the major components of centromeric DNA in this species.
- Published
- 2001
- Full Text
- View/download PDF
37. Evolutionary conservation of kinetochore protein sequences in plants.
- Author
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ten Hoopen R, Manteuffel R, Dolezel J, Malysheva L, and Schubert I
- Subjects
- Amino Acid Sequence, Base Sequence, DNA Primers, DNA, Complementary, Hordeum genetics, Molecular Sequence Data, Sequence Homology, Amino Acid, Zea mays genetics, Evolution, Molecular, Kinetochores metabolism, Plant Proteins genetics
- Abstract
The evolutionary conservation of structural/functional kinetochore proteins has been studied on isolated nuclei and pro-/metaphase chromosomes of mono- and dicot plants. The cross-reactivities of antibodies against human CENPC, CENPE and CENPF, and against maize CENPCa with the centromeric regions of mitotic chromosomes of Vicia faba and/or Hordeum vulgare are shown. Putative homologs of the kinetochore protein SKP1 (suppressor of kinetochore protein 1p of yeast) were found in both species and of CBF5p (centromere binding factor 5 of yeast) in barley. Antibodies against synthetic peptides derived from partial sequences encoding these proteins were produced and recognized the centromeric regions on mitotic chromosomes as detected by indirect immunofluorescence.
- Published
- 2000
- Full Text
- View/download PDF
38. The 5S rRNA gene clusters have a defined orientation toward the nucleolus in Petunia hybrida and Crepis capillaris.
- Author
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Montijn MB, Houtsmuller AB, ten Hoopen R, Oud JL, and Nanninga N
- Subjects
- Asteraceae ultrastructure, Chromosome Mapping, In Situ Hybridization, Fluorescence, Karyotyping, Meristem genetics, Meristem ultrastructure, Metaphase genetics, Microscopy, Confocal, Prophase genetics, Solanaceae ultrastructure, Asteraceae genetics, Multigene Family, Nucleolus Organizer Region genetics, RNA, Ribosomal, 5S genetics, Solanaceae genetics
- Abstract
The 3D localization of the 5S ribosomal RNA genes was studied in cells of the cortex zone of roots in the plant species Petunia hybrida inbred line V26 and in Crepis capillaris. The analysis was carried out on interphase nuclei (both species) and on prophase nuclei (C. capillaris). The 5S ribosomal RNA genes were detected by fluorescence in-situ hybridization and 3D images were obtained by confocal scanning laser microscopy. In both plant species, the 5S ribosomal genes were localized at the short arm of chromosome 2, which, in both plants, also possesses a satellite at its end. Statistical and visual analysis of interphase nuclei showed that: (1) there is a preference for an association of the 5S rRNA gene clusters of the two homologous chromosomes, and (2) the 5S rRNA gene clusters in both species had a preserved spatial position within the interphase nucleus and they tended to be polarized with respect to their neighbouring cells (i.e. a relic telophase orientation). Moreover, tracing of the chromosomal segment between the 5S loci and the active NOR revealed that the homologous chromosomes during early/mid prophase were aligned and that they entered the nucleolus side by side, at least for these chromosome segments. We interpret our data to mean that location of 5S rRNA near the nucleolus favours their functioning in ribosome biogenesis.
- Published
- 1999
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- View/download PDF
39. The spatial localization of T-DNA insertions in petunia interphase nuclei: consequences for chromosome organization and transgene insertion sites.
- Author
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ten Hoopen R, Montijn BM, Veuskens JT, Oud OJ, and Nanninga N
- Subjects
- In Situ Hybridization, Fluorescence, Solanaceae ultrastructure, Cell Nucleus metabolism, Chromosomes, DNA, Bacterial genetics, Interphase, Solanaceae genetics, Transgenes
- Abstract
In an earlier fluorescent in-situ hybridization (FISH) study on petunia (ten Hoopen et al. 1996), we found a considerable discrepancy between the genetic map and the physical map with respect to T-DNA insertions on metaphase chromosomes. For some transgenes we found a preference to integrate near the telomeres. Here, we studied the spatial position of transgenes in interphase nuclei by FISH and 3D-confocal microscopy to elucidate a possible structural preference for the nuclear localization of transgenes. Three transgenes located near telomeres on three different metaphase chromosomes showed a much more internal distribution in interphase root meristem than the telomeres, whereas a proximal transgene appeared to be distributed in a random fashion. The results point to local differences in chromatin compacting along a chromosome. These differences might explain a preference for T-DNA insertion in distal regions of the chromosome.
- Published
- 1999
- Full Text
- View/download PDF
40. A new approach for isolating cell wall mutants in Saccharomyces cerevisiae by screening for hypersensitivity to calcofluor white.
- Author
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Ram AF, Wolters A, Ten Hoopen R, and Klis FM
- Subjects
- Anti-Bacterial Agents pharmacology, Antifungal Agents pharmacology, Caffeine pharmacology, Cell Fractionation, Cell Wall chemistry, Glucosamine analysis, Glucose analysis, Glycoside Hydrolases isolation & purification, Mannose analysis, Microbial Sensitivity Tests, Saccharomyces cerevisiae drug effects, Selection, Genetic, beta-Fructofuranosidase, Aminoglycosides, Benzenesulfonates pharmacology, Cell Wall genetics, Mutation genetics, Saccharomyces cerevisiae genetics
- Abstract
To study cell wall assembly, a simple screening method was devised for isolating cell wall mutants. Mutagenized cells were screened for hypersensitivity to Calcofluor White, which interferes with cell wall assembly. The rationale is that Calcofluor White amplifies the effect of cell wall mutations. As a result, the cells stop growing at lower concentrations of Calcofluor White than cells with normal cell wall. In this way, 63 Calcofluor White-hypersensitive (cwh), monogenic mutants were obtained, ordered into 53 complementation groups. The mannose/glucose ratios of the mutant cell walls varied from 0.15 to 3.95, while wild-type cell walls contained about equal amounts of mannose and glucose. This indicates that both low-mannose and low-glucose cell wall mutants had been obtained. Further characterization showed the presence of three low-mannose cell wall mutants with a mnn9-like phenotype, affected, however, in different genes. In addition, four new killer-resistant (kre) mutants were found, which are presumably affected in the synthesis of beta 1,6-glucan. Most low-glucose cell wall mutants were not killer resistant, indicating that they might be defective in the synthesis of beta 1,3-glucan. Eleven cwh mutants were found to be hypersensitive to papulacandin B, which is known to interfere with beta 1,3-glucan synthesis, and four cwh mutants were temperature-sensitive and lysed at the restrictive temperature. Finally, nine cwh mutants were hypersensitive to caffeine, suggesting that these were affected in signal transduction related to cell wall assembly.
- Published
- 1994
- Full Text
- View/download PDF
41. Vacuolar segregation to the bud of Saccharomyces cerevisiae: an analysis of morphology and timing in the cell cycle.
- Author
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Gomes de Mesquita DS, ten Hoopen R, and Woldringh CL
- Subjects
- Cell Cycle, Cell Division, Fluorescein-5-isothiocyanate, Microscopy, Phase-Contrast, Nocodazole pharmacology, Photomicrography methods, Saccharomyces cerevisiae drug effects, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae growth & development, Time Factors, Saccharomyces cerevisiae ultrastructure, Vacuoles ultrastructure
- Abstract
Vacuoles of Saccharomyces cerevisiae were visualized by phase-contrast microscopy. Visualization was enhanced by adding polyvinylpyrrolidone. Vacuolar segregation during the cell cycle was analysed in 42 individual cells of strain X2180 by time-lapse photomicrography. Within 15 min of bud emergence, more than 80% of the cells contained a vacuolar segregation structure in the form of either a tubule or an alignment of vesicles. The structure emerged from one point of the mother vacuole, then elongated and moved into the bud in a few minutes. The vacuolar segregation structure disappeared, usually within 20 min, before nuclear migration, leaving a separate vacuole in the bud. To test the generality of this observation several strains were grown in the presence of the vacuolar vital dye fluorescein isothiocyanate. The bud size was used to measure progress in the cell cycle. All strains formed vacuolar segregation structures in cells with small buds, although with variations in duration and timing in the cell cycle. In the presence of nocodazole vacuolar segregation occurred normally, thus, microtubules seem not to be essential in this process.
- Published
- 1991
- Full Text
- View/download PDF
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