Lifestagedependent sensitivity of zebrafish Danio rerio to estrogen exposure Ppt Powerpoint Presentation slides Dr. Gerd Maack Medical Slideshow Cloning and Sequencing of Danio rerio zebrafish Polycomb Gene .

Lifestagedependent sensitivity of zebrafish Danio rerio to estrogen exposure

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Slide 1 :

Life-stage-dependent sensitivity of zebrafish (Danio rerio) to estrogen exposure Comparative Biochemistry and Physiology Part C , 139, pages 47-55 Gerd Maack1,2,3 and Helmut Segner1,4 1UFZ Centre for Environmental Research, Department of Chemical Ecotoxicology, Permoserstr. 15, D- 04318 Leipzig, Germany 2Department of Biosciences, University of Exeter, Exeter, EX4 4PS, United Kingdom 3current address: German Federal Environment Agency, Wörlitzer Platz, 06844 Dessau-Roßlau, Germany, gerd.maack@uba.de 4current address: Centre for Fish and Wildlife Health, University of Bern, Länggass-Str. 122, CH-3012 Bern, Switzerland

Slide 2 :

Objectives Establish the ontogeny of gonadal development to clearly define the windows of gonadal sexual differentiation in the used strain. Compare the consequences of estrogen exposure of zebrafish during specific stages of gonad development on reproductive capabilities at the adult stage.

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Background The developmental and reproductive effects of estrogen-active substances are depending on the precise time in the life cycle when the endocrine signal is being released at a specific dosage The critical window is of particular relevance for understanding the effects of EDCs on fish, since even short-term exposure during this life stage may have lasting, irreversible effects on phenotypic sex and reproductive function. From a practical point of view, knowledge on the critical window will help to establish short-term tests for assessing the consequences of developmental EDC exposure on adult reproductive capabilities

Slide 4 :

Zebrafish is a juvenile hermaphrodite or a undifferentiated gonochorist.During ontogeny zebrafish pass through a non-functional female phase when the gonads of all individuals, irrespective of the genetic sex, contain early stage oocytes. Sexual differentiation of zebrafish differs from that of other species such as fathead minnow (Pimephales pimephales) or medaka (Oryzias latipes) Normal Development Background

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Normal Development:Distribution of the zebrafish gonad types during different age classes Age Background

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1. Onset of spawning 2. Number of eggs per female 3. Fertilization Reproductive Parameters Material & Methods Material & Methods

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Zebrafish were exposed to 10ng/L 17?-ethynylestradiol (EE2), during the following different periods of gonad development: Stage of juvenile hermaphroditism or non-functional protogyny when all individuals, irrespective of their final functional sex, display the morphology of an immature ovary, 15-42 days post fertilisation (dpf). Gonad transition stage when the hermaphroditic ovary either proceeds to develop as ovary or resolves into a testis; 43-71 dpf Premature stage when the early ovaries or testis complete developmental differentiation; 72 to 99 dpf. Effects of stage specific exposureExperiment 1 Results Experiment 1

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Slide 19 :

The results from this study indicate that the gonad transition stage of zebrafish is critical with respect to persisting effects of estrogen exposure on reproduction. Estrogen exposure during that gonad transition stage leads to significant alterations of adult reproduction, what is not the case when estrogen exposure takes place during the hermaphroditic or the premature stage of gonad development. Estrogen exposure during that gonad transition stage, however, does not lead to a permanent phenotypic feminisation of the gonads. Conclusion

Slide 20 :

Related Literature Segner, H., Caroll, K., Fenske, M. Janssen, C.R., Maack, G. Pascoe, D. Schäfers, C., Vandenbergh, G.F., Watts, M. and Wenzel, A. 2003. “Identification of endocrine disrupting effects in aquatic organisms: the project IDEA” Ecotoxicology and Environmental Safety, 54, 203-214. Maack, G. and Segner H. 2003. “Morphological development of the gonads in the zebrafish” Journal of Fish Biology, 62, 895-906. Maack, G. Segner H. and Tyler C.R. 2003. “Ontogeny of sexual differentiation in different strains of zebrafish (Danio rerio)” Fish Physiology and Biochemistry, 28, 125-128. Nash J. P., Kime D. E., Van der Ven L., Wester P., Brion F., Maack G, Stahlschmidt-Allner P. and Tyler C.R. 2004. “Environmental concentrations of the pharmaceutical ethynylestradiol impact fish populations” Environmental Health Perspective, 112, 1725–1733. Fenske, M. & Segner, H., 2004. Aromatase modulation alters gonadal differentiation in developing zebrafish (Danio rerio). Aquatic Toxicology 67, 105-126. Fenske, M., Maack, G., Schäfers, C. and Segner, H. 2005. “An environmentally relevant concentration of estrogen induces arrest of male gonadal development in zebrafish, (Danio rerio)”Environmental Toxicology and Chemistry, 24 (5), 1088 – 1098. Schäfers, C., Teigeler, M., Wenzel, A., Maack, G, Fenske, M., and Segner, H. 2007. “Irreversible impairment of reproductive capabilities of zebrafish by an elevated concentration of ethynylestradiol (10 ng/L)”Journal of Toxicology and Environmental Health, Part A, 70:9; 768-779

	gerd.maack@uba.de 1 Years ago. Category: Research

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