Multigenerational effects of the novel brominated flame retardant 1,2,5,6- tetrabromocyclooctane on reproductive performance in Japanese medaka (Oryzias latipes)
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Date
2023
Authors
Devoy, Chloe Elizabeth
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences
Abstract
The brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO), is an endocrine disrupting chemical (EDC) that’s usage is predicted to increase. It is not known if early-life stage exposure of fish to TBCO causes reproductive impairments, as is the case when sexually mature fish are exposed to this chemical. This thesis demonstrates that TBCO is maternally transferred in Japanese medaka (Oryzias latipes), causing multigenerational reproductive impairment. Following parental (F0) exposure, F1 fecundity was decreased by 26.0-56.8%. Plasma concentrations of 17β-estradiol were not significantly decreased. A small decrease in transcript abundance of vitellogenin was observed, but the magnitude was unlikely to have decreased fecundity. However, ex vivo maturation of oocytes from the F1 generation was significantly decreased by 20.0-23.4%, and transcript abundances of genes that regulate oocyte maturation were consistently decreased. This is the first study to demonstrate that early-life stage exposure to an EDC caused decreased fecundity via inhibition of oocyte maturation.
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Keywords
endocrine disrupting chemical , multigenerational , reproduction , oogenesis , Japanese medaka , brominated flame retardant , oocyte maturation