Effects of T-2 mycotoxin on in vitro development and chromatin status of mouse embryos in preimplantation stages

Abstract

T-2 toxin is a mycotoxin produced by phytopathogenic fungi of the Fusarium genus and has many well-studied deleterious effects on mammalian cells and reproductive tract. Despite the wide scale studies, the effects on preimplantation stage embryos are lacking. The aim of our study was to investigate the impact of T-2 on the cleavage stage of mouse embryos with regard to development to blastocysts and nuclear chromatin status. Six-weeks-old BDF1 female mice were superovulated and placed together overnight with mature males. Zygotes were flushed 20 h after human chorionic gonadotropin injection and divided randomly into treated (supplemented with 0.5, 0.75, and 1 ng/ml T-2) and nontreated (control) groups. Embryos were cultured in vitro for 96 h. Developmental stage was evaluated in the 72nd- and 96th-h for assessment of development dynamics. At the end of culture period, blastocysts from treated and control groups with normal morphology were selected for nuclear chromatin analysis. Blastocysts were categorized (grade A, B, and C) depending on the proportion of blasomeres with micronuclei and/or lobulated nuclei. Our data show significant decrease in the proportions of blastocysts in the 0.75 and 1 ng/ml toxin-supplemented groups compared with the control group. Blastocyst rate did not differ in embryos treated with 0.5 ng/ml T-2 but 24 h delay was found in blastocoel formation in all the treated groups. Only grade A (21.1%) and B (78.9%) blastocysts were found in low-toxin-contaminated group similar to the control ones (50–50%). Grade C embryos appeared in the 0.75 ng/ml (10%) treated group and the rate increased significantly (33.3%) in the highest contaminated group. T-2 mycotoxin has a harmful effect on early embryo development which results in decreased blastocyst proportion, delayed blastulation, and increased rate of chromatin damage.