title: Toxicity of a phytosterol mixture to grayling (Thymallus thymallus) during early developmental stages.
abstract: The study concerns the toxicity of a phytosterol mixture, ultrasitosterol, consisting mainly of beta-sitosterol 75.7% and beta-sitostanol 13.0%, to grayling (Thymallus thymallus) embryos. Eyed eggs were exposed to three concentrations (1 microg/l, 10 microg/l, and 50 microg/l) of ultrasitosterol for 4 weeks. Embryos and later on hatched fry were taken for triiodothyronine (T3), thyroxine (T4), and histopathological analyses after 7, 14, 21, and 28 days of exposure. Most of the eggs (>95%) hatched during the first week of exposure, and ultrasitosterol treatment shortened hatching time significantly (p < or = 0.0001) at all exposure concentrations in comparison to the control. Ultrasitosterol did not have any significant effect on T3 or T4 levels in the embryo extracts. However, an interesting observation was that T3 levels increased in all treatments and in the control near the time of hatching. In conclusion, ultrasitosterol showed potential to affect the development of grayling embryos and fry, but further long-term exposure experiments are needed to verify these changes in more detail.
authors.affiliation: Department of Biology, Laboratory of Aquatic Ecology and Ecotoxicology, University of Joensuu, 111, FIN-80101, Joensuu, Finland. Jani.Honkanen@Joensuu.Fi
authors.forename: J O
authors.initials: JO
authors.lastname: Honkanen
authors.forename: A
authors.initials: A
authors.lastname: Kostamo
authors.forename: J V K
authors.initials: JV
authors.lastname: Kukkonen
mesh_terms: D000818:Animals; D006066:Gonads / Q000187:drug effects / Q000196:embryology; D007668:Kidney / Q000187:drug effects / Q000196:embryology; D008099:Liver / Q000187:drug effects / Q000196:embryology; D010063:Ovum / Q000187:drug effects / Q000473:pathology; D010179:Pancreas / Q000187:drug effects / Q000196:embryology; D012487:Salmonidae / Q000196:embryology* / Q000378:metabolism; D012855:Sitosterols / Q000633:toxicity*; D013961:Thyroid Gland / Q000187:drug effects / Q000196:embryology; D013974:Thyroxine / Q000032:analysis; D014284:Triiodothyronine / Q000032:analysis
chemical_list: D012855:Sitosterols; D014284:Triiodothyronine; D013974:Thyroxine