References of "Muller, Marc"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailAutomatic localization of interest points in zebrafish images with tree-based methods
Stern, Olivier ULg; Marée, Raphaël ULg; Aceto, Jessica ULg et al

in Proceedings of the 6th IAPR International Conference on Pattern Recognition in Bioinformatics (2011)

In many biological studies, scientists assess effects of experimental conditions by visual inspection of microscopy images. They are able to observe whether a protein is expressed or not, if cells are ... [more ▼]

In many biological studies, scientists assess effects of experimental conditions by visual inspection of microscopy images. They are able to observe whether a protein is expressed or not, if cells are going through normal cell cycles, how organisms evolve in different experimental conditions, etc. But, with the large number of images acquired in high-throughput experiments, this manual inspection becomes lengthy, tedious and error-prone. In this paper, we propose to automatically detect specific interest points in microscopy images using machine learning methods with the aim of performing automatic morphometric measurements in the context of Zebrafish studies. We systematically evaluate variants of ensembles of classification and regression trees on four datasets corresponding to different imaging modalities and experimental conditions. Our results show that all variants are effective, with a slight advantage for multiple output methods, which are more robust to parameter choices. [less ▲]

Detailed reference viewed: 61 (17 ULg)
Peer Reviewed
See detailZebrafish as model in toxicology/pharmacology.
Voncken, Audrey ULg; Piot, Amandine ULg; Stern, Olivier ULg et al

Poster (2010, March 17)

Detailed reference viewed: 76 (30 ULg)
Full Text
Peer Reviewed
See detailA short upstream promoter region mediates transcriptional regulation of the mouse doublecortin gene in differentiating neurons.
Piens, M.; Muller, Marc ULg; Bodson, Marguerite ULg et al

in BMC Neuroscience (2010), 11(1), 64

ABSTRACT: BACKGROUND: Doublecortin (Dcx), a MAP (Microtubule-Associated Protein), is transiently expressed in migrating and differentiating neurons and thereby characterizes neuronal precursors and ... [more ▼]

ABSTRACT: BACKGROUND: Doublecortin (Dcx), a MAP (Microtubule-Associated Protein), is transiently expressed in migrating and differentiating neurons and thereby characterizes neuronal precursors and neurogenesis in developing and adult neurogenesis. In addition, reduced Dcx expression during development has been related to appearance of brain pathologies. Here, we attempt to unveil the molecular mechanisms controlling Dcx gene expression by studying its transcriptional regulation during neuronal differentiation. RESULTS: To determine and analyze important regulatory sequences of the Dcx promoter, we studied a putative regulatory region upstream from the mouse Dcx coding region (pdcx2kb) and several deletions thereof. These different fragments were used in vitro and in vivo to drive reporter gene expression. We demonstrated, using transient expression experiments, that pdcx2kb is sufficient to control specific reporter gene expression in cerebellar cells and in the developing (E14.5) brain. We determined the temporal profile of Dcx promoter activity during neuronal differentiation of mouse embryonic stem cells (mESC) and found that transcriptional activation of the Dcx gene varies along with neuronal differentiation of mESC. Deletion experiments and sequence comparison of Dcx promoters across rodents, human and chicken revealed the importance of a highly conserved sequence in the proximal region of the promoter required for specific and strong expression in neuronal precursors and young neuronal cells. Further analyses revealed the presence in this short sequence of several conserved, putative transcription factor binding sites: LEF/TCF (Lymphoid Enhancer Factor/T-Cell Factor) which are effectors of the canonical Wnt pathway; HNF6/OC2 (Hepatocyte Nuclear Factor-6/Oncecut-2) members of the ONECUT family; and NF-Y/CAAT (Nuclear Factor-Y). CONCLUSIONS: Studies of Dcx gene regulatory sequences using native, deleted and mutated constructs suggest that fragments located upstream of the Dcx coding sequence are sufficient to induce specific Dcx expression in vitro: in heterogeneous differentiated neurons from mESC, in primary mouse cerebellar neurons (PND3) and in organotypic slices cultures. Furthermore, a region in the 3'-end region of the Dcx promoter is highly conserved across several species and exerts positive control on Dcx transcriptional activation. Together, these results indicate that the proximal 3'-end region of the mouse Dcx regulatory sequence is essential for Dcx gene expression during differentiation of neuronal precursors. [less ▲]

Detailed reference viewed: 45 (15 ULg)
Full Text
Peer Reviewed
See detailRemoval of Androgens and Estrogens from Water by Reactive Materials
Kai, Cai; Phillips, D. H.; Elliott, Christian et al

in Journal of Water Resource and Protection (2010), 2(11), 990-993

Nowadays, endocrine disruptor compounds in the water system have become a concern due to the risk of contamination to wild life and humans even at the nanogram level. Excess estrogens and androgens are a ... [more ▼]

Nowadays, endocrine disruptor compounds in the water system have become a concern due to the risk of contamination to wild life and humans even at the nanogram level. Excess estrogens and androgens are a major contributor group of endocrine compounds. Statistical surveys have shown that dairy farms contribute to over 90% of the total estrogens in the UK and US. An analytical system is being developed to assess the efficiency of reactive materials to remove target hormonal contaminants from dairy farm effluent. This can be achieved using reporter gene assays (RGAs) to detect low level steroid hormones. A preliminary study comparing the efficiency of granular activated carbon, zero-valent iron, and organoclay was carried out using bench-scale evaluations in negative control HPLC water. Their potential ability to remove testosterone and 17-β- estradiol spiked at reported environmental levels was measured by androgenic and estrogenic luminescent reporter assay respectively. [less ▲]

Detailed reference viewed: 43 (10 ULg)
Full Text
Peer Reviewed
See detailAt least two expressed genes for transcription factors Pitx2 and Rpx are present in common carp and are upregulated during winter acclimatization.
Kausel, G.; Vera, T.; Valenzuela, G. et al

in General and Comparative Endocrinology (2010), 169(3), 250-257

The mechanisms of seasonal acclimatization in eurythermal fish such as common carp are not fully understood. Here, we concentrate on the regulation of pituitary factors, as this organ was shown to be ... [more ▼]

The mechanisms of seasonal acclimatization in eurythermal fish such as common carp are not fully understood. Here, we concentrate on the regulation of pituitary factors, as this organ was shown to be highly affected by seasonal changes. We cloned and sequenced two different cDNAs for each of the transcription factors Pitx2 and Rpx, known to play a role in pituitary development. We show that these genes are conserved throughout evolution, to different degrees depending on the specific domain considered. Finally, we show that the cDNAs for both factors are clearly up-regulated during the winter season, in sharp contrast to other regulators such as Pit1 or pituitary hormone genes such as prolactin (prl) and growth hormone (gh). Our results suggest that increased expression of Pitx2 and Rpx contributes to seasonal adaptation of common carp to winter conditions. [less ▲]

Detailed reference viewed: 19 (6 ULg)
Peer Reviewed
See detailRemoval of Androgens and Estrogens from Water by Reactive Materials
Kai, Cai; Phillips, D. H.; Elliott, Chris et al

in 2010 4th International Conference on Bioinformatics and Biomedical Engineering (iCBBE 2010) (2010)

Nowadays, endocrine disruptor compounds in the water system have become a concern due to the risk of contamination to wild life and humans even at the nanogram level. Excess estrogens and androgens are a ... [more ▼]

Nowadays, endocrine disruptor compounds in the water system have become a concern due to the risk of contamination to wild life and humans even at the nanogram level. Excess estrogens and androgens are a major contributor group of endocrine compounds. Statistical surveys have shown that dairy farms contribute to over 90% of the total estrogens in the UK and US. An analytical system is being developed to assess the efficiency of reactive materials to remove target hormonal contaminants from dairy farm effluent. This can be achieved using reporter gene assays (RGAs) to detect low level steroid hormones. A preliminary study comparing the efficiency of granular activated carbon, zero-valent iron, and organoclay was carried out using bench-scale evaluations in negative control HPLC water. Their potential ability to remove testosterone and 17- beta -estradiol spiked at reported environmental levels was measured by androgenic and estrogenic luminescent reporter assay respectively. [less ▲]

Detailed reference viewed: 48 (7 ULg)
Full Text
See detailEvaluation of the endorcine disrupting chemicals contamination in the North Sea porpoise population using in vitro assays
Didimo Imazaki, Pedro Henrique ULg; Brose, François ULg; Van Der Heiden, Edwige ULg et al

Poster (2009)

During the last decades, the production endocrine disrupting chemicals reached such levels that they are now spread all over nature. They are known to be very slowly degraded, decreasing the environmental ... [more ▼]

During the last decades, the production endocrine disrupting chemicals reached such levels that they are now spread all over nature. They are known to be very slowly degraded, decreasing the environmental quality and posing ecological risks. Marine mammals inhabiting polluted environments accumulate high levels of these chemicals, so they can be considered good indicators of marine pollution. Thirteen major organochloride pollutants were chosen to make subject of this study: o,p’-DDD; p,p’-DDD; p,p’-DDE; o,p’-DDT; p,p’-DDT; HCB; α-HCH; β-HCH; γ-HCH; δ-HCH; PCB 138; PCB 153 and PCB 180. All these chemicals will have their endocrine disrupting effects characterized individually and collectively by report gene expression assays. The MCF7-ERE cells used in these assays were produced in the Molecular Biology and Genetic Engineering Laboratory of the University of Liège and are originated from a human mammary carcinoma. They carry a gene expressing the synthesis of luciferase and controlled by oestrogen receptors. Then, the thirteen chemicals will be searched in the blubber tissues of porpoises by the use of gas chromatography-mass spectrometry. The blubber samples will also have their endocrine disrupting effect characterized. For the moment, the estrogenic effects of the HCH isomers were put in evidence. The next steps of this work must be soon accomplished. It is expected a great level of these compounds to be found in the samples. On the other hand, their endocrine disrupting effects and how they act in agonist, antagonist and synergist ways are subject that still needs to be cleared. [less ▲]

Detailed reference viewed: 15 (2 ULg)
Full Text
See detailEvaluation of the contamination of North Sea Porpoises (Phocoena phocoena) by endocrine disrupting chemicals using CG-MS and in vitro assays
Didimo Imazaki, Pedro Henrique ULg; Brose, François ULg; Remacle, Anne-Sophie ULg et al

Poster (2009)

During the last decades, the production of endocrine disrupting chemicals reached such elevated levels that they are now spread all over the environment. Endocrine disrupting chemicals are known to be ... [more ▼]

During the last decades, the production of endocrine disrupting chemicals reached such elevated levels that they are now spread all over the environment. Endocrine disrupting chemicals are known to be very slowly degraded, decreasing the environmental quality and causing ecological risks. Marine mammals inhabiting polluted environments accumulate high quantities of these chemicals, and are good indicators of marine pollution Thirteen major organochloride pollutants (known from literature to contaminate north sea porpoise) were chosen in this study – o,p’-DDD; p,p’-DDD; p,p’-DDE; o,p’-DDT; p,p’-DDT; HCB; α-HCH; β-HCH; γ-HCH; δ-HCH; PCB 138; PCB 153 and PCB 180. The thirteen chemicals were tested individually and in mixtures by the use of report gene expression assays. The MCF7-ERE cells used in the assays were originated from MCF7 human mammary tumor cells transfected with the ERE-luciferase reporter system. Preliminary results suggest that o,p’-DDD; p,p’-DDD; o,p’-DDT; HCB; β-HCH; δ-HCH; PCB 138 and PCB 180 are able to stimulate the luciferase expression of MCF7-ERE cells when they are present individually or in mixtures. No synergism was observed within mixtures. When MCF7-ERE cells were exposed to the chemicals and 17β-oestradiol simultaneously, p,p’-DDE; α-HCH; PCB 138 and PCB 180 could raise the luciferase expression in comparison to the exposition of 17β-oestradiol alone; on the other hand, o,p’-DDD; p,p’-DDT; HCB; β-HCH; γ-HCH and δ-HCH seem to inhibit the luciferase expression at low doses. In the next step, the pollutants will be searched and quantified in the blubber tissue of porpoises by use of gas chromatography-mass spectrometry. The blubber tissue samples will also have their endocrine disrupting effects characterized. This work is ongoing and It is expected a relevant level of these compounds to be found in the samples. Conversely, their endocrine disrupting effects and how they act in agonist, antagonist ways are subject that still needs to be studied. [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailCYP1A1 induction and CYP3A4 inhibition by the fungicide imazalil in the human intestinal Caco-2 cells-Comparison with other conazole pesticides
Sergent, Thérèse; Dupont, Isabelle; Jassogne, Coralie et al

in Toxicology Letters (2009), 184(3), 159-168

Imazalil (IMA) is a widely used imidazole-antifungal pesticide and. therefore. a food contaminant. This compound is also used as a drug (enilconazole). As intestine is the first site of exposure to ... [more ▼]

Imazalil (IMA) is a widely used imidazole-antifungal pesticide and. therefore. a food contaminant. This compound is also used as a drug (enilconazole). As intestine is the first site of exposure to ingested drugs and pollutants, we have investigated the effects of IMA, at realistic intestinal concentrations, on xenobiotic-metabolizing enzymes and efflux pumps by using Caco-2 cells, as a validated in vitro model of the human intestinal absorptive epithelium. For comparison, other conazole fungicides, i.e. ketoconazole, propiconazole and tebuconazole. were also studied. IMA induced cytochrome P450 (CYP) 1A1 activity to the same extent as benzo(a)pyrene (B(a)P) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), in a dose-and time-dependent manner. Cell-free aryl hydrocarbon receptor (AhR) binding assay and reporter gene assay suggested that IMA is not an AhR-ligand, implying that IMA-mediated induction should involve an AhR-independent pathway. Moreover, IMA strongly inhibited the CYP3A4 activity in 1,25-vitamin D-3-induced Caco-2 cells. The other fungicides had weak or nil effects on CYP activities. Study of the apical efflux pump activities revealed that ketoconazole inhibited both P-glycoprotein (Pgp) and multidrug resistance-associated protein 2 (MRP-2) or breast cancer resistance protein (BCRP), whereas IMA and other fungicides did not. Our results imply that coingestion of IMA-contaminated food and CYP3A4- or CYP1A1-metabolizable drugs or chemicals could lead to drug bioavailability modulation or toxicological interactions, with possible adverse effects for human health. (C) 2008 Elsevier Ireland Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 85 (24 ULg)
Full Text
Peer Reviewed
See detailFood flavonoid aryl hydrocarbon receptor-mediated agonistic/antagonistic/synergic activities in human and rat reporter gene assays
Van Der Heiden, Edwige ULg; Bechoux, Nathalie ULg; Muller, Marc ULg et al

in Analytica Chimica Acta (2009), 637

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic ... [more ▼]

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic-, time-, dose-, species- and tissue-dependent AhR-mediated agonistic/ antagonistic activities of three food flavonoids: quercetin, chrysin and genistein. To that end, four stably transfected cell lines were used in cell-based luciferase reporter gene assays: three lines were transformed with the ptKLuc vector harbouring four dioxinresponsive elements (DREs) upstream of the thymidine kinase promoter and the luciferase gene (HepG2-Luc, T-47D-Luc and H4IIE-ULg). The fourth is a patented cell line transformed with a different construct: H4IIE DR-CALUX®. Both H4IIE cells were compared for their genetic construction. Human hepatoma (HepG2-Luc) and human breast tumour (T-47D-Luc) cells were compared for tissue-dependent effects. Rat hepatoma (H4IIE-ULg) and human hepatoma (HepG2-Luc) cellswere compared for species-dependent activities.We concluded that quercetin, chrysin and genistein act in a time-, dose-, species- and tissue-specific way. For example, genistein displayed agonistic activities when exposed to rat hepatoma cells during 6h but not after 24 h. Flavonoids displayed agonistic/antagonistic activities in human breast tumour cells, depending on the exposure time, while in human hepatoma cells, only antagonistic activities of flavonoids were measured. In addition, we report, in all the cells, a synergy between an isoflavone and two food contaminants; the 2,3,7,8-tetrachlorodibenzop- dioxin and 3-methylcholanthrene, a PAH. In rat cells, this synergy occurred when cells were exposed to flavonoids and contaminant for 6h, while it was observed in human cells only after 24 h. [less ▲]

Detailed reference viewed: 77 (13 ULg)
Full Text
Peer Reviewed
See detailDetection of glucocorticoid bioactivity in bovine urine samples using a reporter gene assay
Connolly, Lisa; Cai, Kai; Van Der Heiden, Edwige ULg et al

in Analytica Chimica Acta (2009), 637

The illegal use of anabolic substances in the meat producing industry is an ongoing problem due to the continual production of new synthetic compounds and/or the practice of lowlevel cocktail ... [more ▼]

The illegal use of anabolic substances in the meat producing industry is an ongoing problem due to the continual production of new synthetic compounds and/or the practice of lowlevel cocktail administration to avoid detection by the surveillance schemes of EU member states National Plan surveillance systems. We present a highly sensitive reporter gene assay and sample extraction procedure based on a two step solid phase extraction and high performance liquid chromatography, developed for the detection of glucocorticoid abuse in bovine urine. The assay is capable of detecting compounds with glucocorticoid bioactivity and is extremely sensitive with an EC50 of 0.79 ngmL−1 for dexamethasone. New or unknown compounds with glucocorticoid bioactivity and low-level cocktail mixtures are detectable by this assay. Cross-reactivity data for a range of 11 -hydroxyglucocorticoids has been provided. This assay shows low interference from the 11-keto prohormones and other steroidal hormones. The assay may be suitable for application in other matrices such as hair. In conclusion this screening assay offers advantages over existing analytical techniques. [less ▲]

Detailed reference viewed: 50 (12 ULg)
Peer Reviewed
See detailModulation of cytochrome P450 1A1 expression and activity in intestinal Caco-2 cells by components of Ginkgo biloba-based dietary supplements
Ribonnet, Laurence; Callebaut, Alfons; Scippo, Marie-Louise ULg et al

in Toxicology Letters (2009), 189

Detailed reference viewed: 33 (12 ULg)
Full Text
Peer Reviewed
See detailIdentification of differentially expressed genes in the zebrafish hypothalamic-pituitary axis.
Toro, Sabrina; Wegner, Jeremy; Muller, Marc ULg et al

in Gene Expression Patterns (2009), 9(4), 200-8

The vertebrate hypothalamic-pituitary axis (HP) is the main link between the central nervous system and endocrine system. Although several signal pathways and regulatory genes have been implicated in ... [more ▼]

The vertebrate hypothalamic-pituitary axis (HP) is the main link between the central nervous system and endocrine system. Although several signal pathways and regulatory genes have been implicated in adenohypophysis ontogenesis, little is known about hypothalamic-neurohypophysial development or when the HP matures and becomes functional. To identify markers of the HP, we constructed subtractive cDNA libraries between adult zebrafish hypothalamus and pituitary. We identified previously published genes, ESTs and novel zebrafish genes, some of which were predicted by genomic database analysis. We also analyzed expression patterns of these genes and found that several are expressed in the embryonic and larval hypothalamus, neurohypophysis, and/or adenohypophysis. Expression at these stages makes these genes useful markers to study HP maturation and function. [less ▲]

Detailed reference viewed: 21 (4 ULg)