References of "Muller, Marc"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailA panel of biological tests reveals developmental effects of pharmaceutical pollutants on late stage zebrafish embryos.
Pruvot, Benoist ULg; Quiroz O' Donova, Yobhana ULg; Voncken, Audrey ULg et al

in Reproductive Toxicology (2012)

Standard toxicological assays using the zebrafish model system evaluate lethality and teratogenicity upon exposure during the first two days after fertilization. We tested the biological effects of ... [more ▼]

Standard toxicological assays using the zebrafish model system evaluate lethality and teratogenicity upon exposure during the first two days after fertilization. We tested the biological effects of several widely used drugs on zebrafish by acute treatment for 24hours starting at late embryonic stages, between 48 and 72hours post-fertilization. For 4 out of 6 compounds, we observed a higher sensitivity of late stage zebrafish embryos for general toxicity (lethality) compared to younger embryos. Morphological defects such as edema, body curvature, delayed growth, decreased heart rate and locomotion were observed for each of the compounds tested, often at sublethal concentrations. Gene expression studies on a set of four selected genes revealed a specific regulatory pattern for the different compounds tested. Our results allow us to compare various toxicological endpoints and may contribute to the design of a rational high throughput approach using the zebrafish model. [less ▲]

Detailed reference viewed: 99 (55 ULg)
Full Text
Peer Reviewed
See detailStructurally conserved C-RFa revealed prolactin releasing activity in vitro and gene expression changes in pituitary of seasonally acclimatized carp.
Romero, Alex; Montefusco-Siegmund, Rodrigo; Valenzuela, Guillermo et al

in Biological Research (2012), 45(2), 183-92

Here we show the cloning and characterization of a novel homolog of prepro C-RFa cDNA from Cyprinus carpio. The deduced preprohormone precursor of 115 amino acids leads to a mature bioactive peptide of 20 ... [more ▼]

Here we show the cloning and characterization of a novel homolog of prepro C-RFa cDNA from Cyprinus carpio. The deduced preprohormone precursor of 115 amino acids leads to a mature bioactive peptide of 20 amino acids with identical sequence to other teleost C-RFa. Modeling of the mature C-RFa peptide highlighted significant similarity to homologous human PrRP20, specifically the conserved amphipathic system defined by the C-terminal alpha-helix. Clearly, the synthetic C-RFa peptide stimulated prolactin release from primary cultured fish pituitary cells. For the first time, significant variation was shown in C-RFa mRNA and protein levels in the hypothalamus and pituitary between summer- and winter-acclimatized carp. Furthermore, C-RFa protein distribution in carp central nervous tissue was visualized by immunodetection in fibers and cells in hypothalamus, olfactory tract, cerebellum and pituitary stalk. In conclusion, we demonstrated the structure conservation of C-RFa in teleosts and mammals and immunopositive cells and fibers for C-RFa in brain areas. Finally, the increase of C-RFa expression suggests the participation of this hypothalamic factor in the mechanism of modulation in PRL expression in carp. [less ▲]

Detailed reference viewed: 31 (6 ULg)
Full Text
Peer Reviewed
See detailTreatment of estrogens and androgens in dairy wastewater by a constructed wetland system.
Cai, Kai; Elliott, Christopher T; Phillips, Debra H et al

in Water Research (2012), 46(7), 2333-43

Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens ... [more ▼]

Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens, there is limited data on the presence of hormones in this type of treatment system. The objective of this study was to evaluate the ability of the CWS to reduce estrogenic and androgenic hormone concentration in dairy wastewater. This was achieved through a year long study on dairy wastewater samples obtained from a surface flow CWS. Analysis of hormonal levels was performed using a solid phase extraction (SPE) sample clean-up method, combined with reporter gene assays (RGAs) which incorporate relevant receptors capable of measuring total estrogenic or androgenic concentrations as low as 0.24 ng L(-1) and 6.9 ng L(-1) respectively. Monthly analysis showed a mean removal efficiency for estrogens of 95.2%, corresponding to an average residual concentration of 3.2 ng L(-1) 17beta-estradiol equivalent (EEQ), below the proposed lowest observable effect concentration (LOEC) of 10 ng L(-1). However, for one month a peak EEQ concentration of 115 ng L(-1) was only reduced to 18.8 ng L(-1). The mean androgenic activity peaked at 360 ng L(-1) and a removal efficiency of 92.1% left an average residual concentration of 32.3 ng L(-1) testosterone equivalent (TEQ). The results obtained demonstrate that this type of CWS is an efficient system for the treatment of hormones in dairy wastewater. However, additional design improvements may be required to further enhance removal efficiency of peak hormone concentrations. [less ▲]

Detailed reference viewed: 73 (15 ULg)
Full Text
Peer Reviewed
See detailPhenotype Classification of Zebrafish Embryos by Supervised Learning
Jeanray, Nathalie ULg; Marée, Raphaël ULg; Pruvot, Benoist ULg et al

Conference (2011, September 02)

Detailed reference viewed: 43 (13 ULg)
Full Text
Peer Reviewed
See detailZebrafish Skeleton Measurements using Image Analysis and Machine Learning Methods
Stern, Olivier ULg; Marée, Raphaël ULg; Aceto, Jessica ULg et al

Poster (2011, May 20)

The zebrafish is a model organism for biological studies on development and gene function. Our work aims at automating the detection of the cartilage skeleton and measuring several distances and angles to ... [more ▼]

The zebrafish is a model organism for biological studies on development and gene function. Our work aims at automating the detection of the cartilage skeleton and measuring several distances and angles to quantify its development following different experimental conditions. [less ▲]

Detailed reference viewed: 66 (19 ULg)
Full Text
Peer Reviewed
See detailLeukemic cell xenograft in zebrafish embryo for investigating drug efficacy.
Pruvot, Benoist ULg; Jacquel, Arnaud; Droin, Nathalie et al

in Haematologica (2011), 96(4), 612-6

Zebrafish were proposed as an alternative to mammalian models to assess the efficacy and toxicity of antileukemic drugs. Due to the limited number of transgenic zebrafish leukemia models, we explored ... [more ▼]

Zebrafish were proposed as an alternative to mammalian models to assess the efficacy and toxicity of antileukemic drugs. Due to the limited number of transgenic zebrafish leukemia models, we explored human leukemic cell xenograft in zebrafish embryos. Human leukemic cell lines and blast cells sorted from patients with acute myelogenous leukemia were injected 48 hours post-fertilization and remained in the circulation of zebrafish embryos for several days without affecting their development. Imatinib and oxaphorines did not demonstrate any toxicity on normal zebrafish embryos and decreased the leukemic burden in animals xenografted with sensitive leukemic cell lines. Two other molecules, all-trans retinoic acid and the translation inhibitor 4EGI-1, demonstrated teratogenic effects at concentrations shown to be efficient in vitro, which precluded investigation of their antileukemic activity in such models. Altogether, xenografted leukemic cells in zebrafish embryos are a pharmacologically relevant model for screening non-teratogenic drugs. [less ▲]

Detailed reference viewed: 41 (5 ULg)
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: 96 (22 ULg)
Full Text
Peer Reviewed
See detailAreas of Research:Life sciences:Animal Physiology
Horn, Eberhard; van Loon, Jack; Aceto, Jessica ULg et al

in Beyens, Daniel; Carotenuto, Luigi; van Loon, Jack (Eds.) et al Laboratory Science with Space Data: Accessing and using space-experiment data (2011)

Detailed reference viewed: 25 (10 ULg)
Full Text
Peer Reviewed
See detailThe application of reporter gene assays for the detection of endocrine disruptors in sport supplements
Plotan, Monica; Elliott, Chris; Scippo, Marie-Louise ULg et al

in Analytica Chimica Acta (2011), 700

The increasing availability and use of sports supplements is of concern as highlighted by a number of studies reporting endocrine disruptor contamination in such products. The health food supplement ... [more ▼]

The increasing availability and use of sports supplements is of concern as highlighted by a number of studies reporting endocrine disruptor contamination in such products. The health food supplement market, including sport supplements, is growing across the Developed World. Therefore, the need to ensure the quality and safety of sport supplements for the consumer is essential. <br />The development and validation of two reporter gene assays coupled with solid phase sample preparation enabling the detection of estrogenic and androgenic constituents in sport supplements is reported. Both assays were shown to be of high sensitivity with the estrogen and androgen reporter gene assays having an EC50 of 0.01 ng mL-1 and 0.16 ng mL-1 respectively. <br />The developed assays were applied in a survey of 63 sport supplements samples obtained across the Island of Ireland with an additional seven reference samples previously investigated using LC-MS/MS. Androgen and estrogen bio-activity was found in 71 % of the investigated samples. Bio-activity profiling was further broken down into agonists, partial agonists and antagonists. Supplements (13) with the strongest estrogenic bio-activity were chosen for further investigation. LC-MS/MS analysis of these samples determined the presence of phytoestrogens in seven of them. Supplements (38) with androgen bio-activity were also selected for further investigation. Androgen agonist bio-activity was detected in 12 supplements, antagonistic bio-activity was detected in 16 and partial antagonistic bio-activity was detected in 10. A further group of supplements (7) did not present androgenic bio-activity when tested alone but enhanced the androgenic agonist bio-activity of dihydrotestosterone when combined. <br />The developed assays offer advantages in detection of known, unknown and low-level mixtures of endocrine disruptors over existing analytical screening techniques. For the detection and identification of constituent hormonally active compounds the combination of biological and physio-chemical techniques is optimal. [less ▲]

Detailed reference viewed: 120 (26 ULg)
Full Text
See detailFood interactions : effects on health, consumer perception and impact on agro-food industries “FOODINTER”.
Scippo, Marie-Louise ULg; Blust, Ronny; Boniver, Delphine et al

Report (2011)

Detailed reference viewed: 59 (17 ULg)
Full Text
Peer Reviewed
See detailEndocrine disrupting effects of zearalenone, alpha- and beta-zearalenol at the level of nuclear receptor binding and steroidogenesis.
Frizzell, C; Ndossi, D; Verhaegen, S et al

in Toxicology Letters (2011), 206(2), 210-217

The mycotoxin zearalenone (ZEN) is a secondary metabolite of fungi which is produced by certain species of the genus Fusarium and can occur in cereals and other plant products. Reporter gene assays ... [more ▼]

The mycotoxin zearalenone (ZEN) is a secondary metabolite of fungi which is produced by certain species of the genus Fusarium and can occur in cereals and other plant products. Reporter gene assays incorporating natural steroid receptors and the H295R steroidogenesis assay have been implemented to assess the endocrine disrupting activity of ZEN and its metabolites alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL). alpha-ZOL exhibited the strongest estrogenic potency (EC(50) 0.022+/-0.001 nM), slightly less potent than 17-beta estradiol (EC(50) 0.015+/-0.002 nM). ZEN was ~70 times less potent than alpha-ZOL and twice as potent as beta-ZOL. Binding of progesterone to the progestagen receptor was shown to be synergistically increased in the presence of ZEN, alpha-ZOL or beta-ZOL. ZEN, alpha-ZOL or beta-ZOL increased production of progesterone, estradiol, testosterone and cortisol hormones in the H295R steroidogenesis assay, with peak productions at 10 muM. At 100 muM, cell viability decreased and levels of hormones were significantly reduced except for progesterone. beta-ZOL increased estradiol concentrations more than alpha-ZOL or ZEN, with a maximum effect at 10 muM, with beta-ZOL (562+/-59 pg/ml)>alpha-ZOL (494+/-60 pg/ml)>ZEN (375+/-43 pg/ml). The results indicate that ZEN and its metabolites can act as potential endocrine disruptors at the level of nuclear receptor signalling and by altering hormone production. [less ▲]

Detailed reference viewed: 64 (2 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: 87 (35 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: 27 (7 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: 106 (18 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: 67 (11 ULg)