title: The environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin disturbs the establishment and maintenance of cell polarity in preimplantation rat embryos.
abstract: Maternal exposure to the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces a variety of defects in compaction-stage embryos, including monopolar spindle formation, errors in chromosome segregation, and fragmentation resulting from aberrant cytokinesis. In this study, we investigated the possibility that a failure in centrosome duplication, separation, or positioning within blastomeres might underlie the observed effects of TCDD on early embryos. The subcellular localization of the centrosomal marker TUBG1 was analyzed in preimplantation embryos collected from female rats exposed to either chronic (50 ng kg(-1) wk(-1) for 3 wk) or acute (50 ng/kg or 1 microg/kg at proestrus) doses of TCDD. In treated embryos, interphase TUBG1 foci were more abundant and cortically displaced when compared to those in controls. At prophase, some blastomeres exhibited a single large perinuclear TUBG1 aggregate, suggesting a failure in centrosome duplication or separation. Furthermore, the presence of monopolar spindles at metaphase was confirmed by the localization of TUBG1 to the single spindle pole. Therefore, the misregulation of centrosome number and localization, as indicated by TUBG1 staining, may contribute to errors in chromosome segregation and cytokinesis in embryos following maternal TCDD exposure.
authors.affiliation: The Center for Reproductive Sciences, Department of Molecular and Integrative Physiology, and Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas 66103, USA.
authors.forename: Karla J
authors.initials: KJ
authors.lastname: Hutt
authors.forename: Zhanquan
authors.initials: Z
authors.lastname: Shi
authors.forename: Brian K
authors.initials: BK
authors.lastname: Petroff
authors.forename: David F
authors.initials: DF
authors.lastname: Albertini
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D016764:Cell Polarity / Q000187:drug effects*; D018385:Centrosome / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity; D005260:Female; D042541:Intracellular Space; D018811:Maternal Exposure; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013723:Teratogens / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D014404:Tubulin / Q000187:drug effects
chemical_list: D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D013723:Teratogens; D014404:Tubulin