Dose-Dependent Early Life Stage Toxicities in Xenopus laevis Exposed In Ovo to Selenium.
Selenium (Se) is a developmental toxicant in oviparous vertebrates. The adverse reproductive effects of Se toxicity have been predominantly investigated in fishes and birds with only a few studies focusing on amphibians. The objective of this study was to determine tissue-based toxicity thresholds for early life stage Se toxicities in Xenopus laevis as a consequence of in ovo exposure through maternal transfer of dietary Se. Following a 68-day dietary exposure to food augmented with l-selenomethionine (SeMet) at measured concentrations of 0.7 (control), 10.9, 30.4, or 94.2 μg Se/g dry mass (d.m.), adult female X. laevis were bred with untreated males, and resulting embryos were incubated until 5 days postfertilization (dpf). The measured Se concentrations in eggs were 1.6, 10.8, 28.1, and 81.7 μg Se/g d.m., respectively. No biologically significant effects were observed on fertilization success, hatchability, or mortality in offspring. Frequency and severity of morphological abnormalities were significantly greater in 5 dpf tadpoles from the highest exposure group when compared to the control, with eye lens abnormalities being the most prominent of all abnormalities. The estimated EC10 value for frequency of total early life stage abnormalities was 44.9 μg Se/g egg d.m., which suggests that this amphibian species is less sensitive to in ovo Se exposure than most of the fish species studied to date.
Toxicology Graduate Program, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5B3.
Anita J
AJ
Massé
Stantec Consulting Ltd. , Burnaby, British Columbia, Canada V5H 0C6.
Jorgelina R
JR
Muscatello
Toxicology Centre, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5B3.|Department of Veterinary Biomedical Sciences, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5B4.
David M
DM
Janz
D000818:Animals; D004032:Diet; D004305:Dose-Response Relationship, Drug; D054750:Ecotoxicology / Q000379:methods; D004625:Embryo, Nonmammalian / Q000187:drug effects; D005260:Female; D007814:Larva / Q000187:drug effects; D008297:Male; D018811:Maternal Exposure; D009026:Mortality; D010063:Ovum / Q000187:drug effects*; D012098:Reproduction / Q000187:drug effects; D012643:Selenium / Q000008:administration & dosage / Q000032:analysis / Q000633:toxicity*; D012645:Selenomethionine / Q000032:analysis; D014982:Xenopus laevis / Q000196:embryology
D012645:Selenomethionine; D012643:Selenium