Jasplakinolide (JAS), a cytotoxic natural product, induces actin polymerization and increases microfilament assembly. The knowledge about the effect of JAS on oocyte meiosis in mammals is limited. The present study was to investigate the effect of JAS on the events of oocyte meiosis such as spindle configuration, chromosome alignment and segregation and oocyte maturation. The results showed that (1) JAS affected oocyte maturation and haploid composition of matured oocytes in a dose-dependent manner. The maturation rates were 70.3, 53.1, 39.7 and 20.6% after culturing oocytes in JAS at 100, 200, 300 and 400 nM for 24 h, respectively, which were significantly lower than the control group (86.2%); (2) JAS treatment caused drastically irregular meiotic spindle formation and destroyed microfilament organization; (3) JAS altered the chromosomal alignment, homologous chromosomal segregation and resulted in failure of PB1 extrusion. The majority of the non-PB1 oocytes was arrested at the tetrad state in which homologous chromosomes and sister chromatids were clearly visible; (4) pretreatment of oocytes with JAS affected the oocyte maturation even after subsequent incubation in normal maturation medium; (5) oocytes at metaphase I were much more sensitive to JAS than oocytes at anaphase I stage. In conclusion, JAS affected polar body extrusion, spindle morphology, microfilament organization and chromosome composition in a dose dependent manner and oocyte meiotic stage dependent manner.

Key words: Jasplakinilide, oocyte meiosis, spindle, microfilament, chromosome.