References of "Muller, Marc"
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See detailDevelopmental defects in zebrafish for classification of EGF pathway inhibitors.
Pruvot, Benoist ULg; Curé, Yoann ULg; Djiotsa, Joachim et al

in Toxicology and Applied Pharmacology (in press)

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See detailFunctional study of the Ser/Arg-rich splicing factor SRSF5a during zebrafish embryonic development.
Joris, Marine ULg; Larbuisson, Arnaud ULg; Muller, Marc ULg et al

Poster (2013, April 18)

To investigate the role of the splicing factor SRSF5a during zebrafish embryonic development, we performed SRSF5a knockdown by morpholino microinjection and we analysed control and morphant transcriptomes ... [more ▼]

To investigate the role of the splicing factor SRSF5a during zebrafish embryonic development, we performed SRSF5a knockdown by morpholino microinjection and we analysed control and morphant transcriptomes using RNA sequencing. [less ▲]

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See detailFgf receptors Fgfr1a and Fgfr2 control the function of pharyngeal endoderm in late cranial cartilage development.
Larbuisson, Arnaud ULg; Dalcq, Julia ULg; Martial, Joseph ULg et al

in Differentiation; research in biological diversity (2013)

Cranial cartilage derives mainly from cranial neural crest cells and its formation requires fibroblast growth factor (Fgf) signaling for early differentiation and survival of developing chondrocytes as ... [more ▼]

Cranial cartilage derives mainly from cranial neural crest cells and its formation requires fibroblast growth factor (Fgf) signaling for early differentiation and survival of developing chondrocytes as well as patterning of the endodermal pouches. Here, we investigate the role of Fgf receptors in chondrocyte maturation at later stages, beyond 24hpf. Using inducible expression of a dominant-negative Fgf receptor, we show that Fgf signaling is required around 30hpf for correct cartilage formation. The receptor genes fgfr1a and fgr2 are expressed in pharyngeal endodermal pouches after 24hpf or 26hpf, respectively. Depletion of any of these two receptors by microinjection of antisense morpholinos results in severe defects in cartilage formation at 4dpf and a decrease in expression of the late chondrocyte markers barx1 and runx2b. Although endodermal pouches are correctly formed and patterned, receptor knock down leads to decreased expression of runx3, egr1 and sox9b in this tissue, while expression of fsta, coding for a secreted BMP/Tgfss inhibitor, is clearly increased. Rescue experiments revealed that each Fgfr1a or Fgfr2 receptor is able to compensate for the loss of the other. Thus, we show that minimal amounts of Fgfr1a or Fgfr2 are required to initiate a regulatory cascade in pharyngeal endoderm reducing expression of fsta, thereby allowing correct BMP signaling to the maturing chondrocytes of the head cartilage. [less ▲]

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See detailRemoval of natural hormones in dairy farm wastewater using reactive and sorptive materials
Cai; Phillips; Elliott et al

in Science of the Total Environment (2013), 461-462

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See detailRUNX3, EGR1 AND SOX9B FORM A REGULATORY CASCADE REQUIRED TO MODULATE BMP-SIGNALING DURING CRANIAL CARTILAGE DEVELOPMENT IN ZEBRAFISH.
Dalcq, Julia ULg; Pasque, Vincent; Ghaye, Aurélie ULg et al

in PLoS ONE (2012), in press

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions ... [more ▼]

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions between neural crest cells and surrounding endodermal, ectodermal and mesodermal tissues. In this study, we show that the endodermal factors Runx3 and Sox9b form a regulatory cascade with Egr1 resulting in transcriptional repression of the fsta gene, encoding a BMP antagonist, in pharyngeal endoderm. Using a transgenic line expressing a dominant negative BMP receptor or a specific BMP inhibitor (dorsomorphin), we show that BMP signaling is indeed required around 30 hpf in the neural crest cells to allow cell differentiation and proper pharyngeal cartilage formation. Runx3, Egr1, Sox9b and BMP signaling are required for expression of runx2b, one of the key regulator of cranial cartilage maturation and bone formation. Finally, we show that egr1 depletion leads to increased expression of fsta and inhibition of BMP signaling in the pharyngeal region. In conclusion, we show that the successive induction of the transcription factors Runx3, Egr1 and Sox9b constitutes a regulatory cascade that controls expression of Follistatin A in pharyngeal endoderm, the latter modulating BMP signaling in developing cranial cartilage in zebrafish. [less ▲]

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See detailA panel of biological tests reveals developmental effects of pharmaceutical pollutants on late stage zebrafish embryos.
Pruvot, Benoist ULg; Quiroz, Yobhana; 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 ▲]

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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 ▲]

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See detailThe HMG-Box Transcription Factor Sox4b Is Required for Pituitary Expression of gata2a and Specification of Thyrotrope and Gonadotrope Cells in Zebrafish.
Quiroz O'Donova, Yobhana ULg; Lopez, Marie-Josée ULg; Mavropoulos, A et al

in Molecular Endocrinology (2012), 26(6), 1014-1027

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and ... [more ▼]

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24 h after fertilization (hpf) and later in the entire head region including the pituitary. At 48 hpf, sox4b mRNA colocalizes with that for TSH (tshbeta), glycoprotein subunit alpha (gsualpha), and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knockdown or expression of a dominant-negative Sox4 mutant, leads to a drastic decrease in tshbeta and gsualpha expression and reduced levels of gh, whereas other anterior pituitary gland markers including prl, slbeta, pomc, and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tshbeta and gsualpha expression at 48 hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tshbeta and gsualpha expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhbeta and fshbeta) at 4 d after fertilization. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary. [less ▲]

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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 ▲]

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See detailPhenotype Classification of Zebrafish Embryos by Supervised Learning
Jeanray, Nathalie ULg; Marée, Raphaël ULg; Pruvot, Benoist ULg et al

Conference (2011, September 02)

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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 ▲]

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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)

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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 ▲]

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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)

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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 ▲]

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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 ▲]

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