Submitted May 9, 2007
Returned for revision June 5, 2007
Accepted July 23, 2007
Gamete Biology
Exposure of Oocytes to the Fusarium Toxins Zearalenone and Deoxynivalenol Causes Aneuploidy and Abnormal Embryo Development in Pigs
Hassan Malekinejad ,
Eric J. Schoevers ,
Ineke J.J.M. Daemen ,
Carla Zijlstra ,
Ben Colenbrander ,
Johanna Fink-Gremmels ,
and
Bernard A.J. Roelen *
* To whom correspondence should be addressed. E-mail: b.a.j.roelen{at}uu.nl.
Abstract
Fungi of the Fusarium species can infect food and feed commodities and produce the mycotoxins zearalenone (ZEA) and deoxynivalenol (DON). Since both toxins have been reported to reduce fertility, the mechanisms of ZEA and DON on inhibition of oocyte maturation was examined. Porcine oocytes were matured in the presence of ZEA (a mycotoxin with estrogen-like activity), 17beta-estradiol and DON (all 3.12 µM). ZEA, 17beta-estradiol and DON inhibited oocyte maturation and caused approximately 34% of the oocytes to form an aberrant spindle. Different ratios of ZEA/DON did not lead to a more severe inhibition of oocyte maturation. Both mycotoxins caused abnormal formation of the meiotic spindle. The developmental competence of oocytes matured in the presence of mycotoxins was further investigated after in vitro fertilization. Presence of ZEA (3.12 µM) during maturation reduced the percentages of oocytes that cleaved and formed a blastocyst to about 12%, compared with 25% of control oocytes. Maturation in the presence of equimolar concentrations of DON was not compatible with development. The ploidy of blastomeres from blastocysts derived from mycotoxin-exposed ooctes was analysed with fluorescent in situ hybridisation. All blastocysts, even of the control group, contained at least one blastomere with abnormal ploidy, but the variation in the percentages of aneuploid blastomeres was significantly larger in embryos from oocytes exposed to mycotoxins. It is concluded that ZEA and DON can lead to abnormal spindle formation leading to less fertile oocytes and embryos with abnormal ploidy and that the effects of ZEA and DON are not synergistic.
Key words:
Embryo •
Toxicology •
Early development •
In vitro fertilization •
Meiosis
