关键词: 牛卵母细胞;细胞松弛素B;减数分裂;微丝;微管;染色体

Abstract:

Cytochalasin B (CB), a reagent inhibiting actin polymerization, can inhibit the assembly of actin and prevent cytokinesis and polar body (PB1) emission, and it usually is used to study the formation and dynamic changes of meiotic (mitotic) apparatus. In this study, the effect of CB on meiotic spindle configuration, chromosome alignment and separation was investigated after the oocytes were incubated at the presence of 7.5 μg/mL CB. The results showed that CB inhibited the emission of PB1 and resulted in the formation of abnormal patterns of chromosomal alignment and separation such as the incomplete separation of homologous chromosomes. CB treatment caused meiotic arrest at anaphase Ⅰ stage and induced the formation of 2 groups of chromosomes, which then moved toward in proximity or merged entirely to yield the formation of diploid oocytes. Meanwhile, CB treatment led to the disfiguration of spindle microtubules and induced 2 spindles, a large spindle, and multiple-poles spindles. CB also affected the microfilament distribution. Almost no or less microfilaments were observed around the chromosomes, and their distribution in the sub-cortical areas was less and uneven. These results suggested that meiosis require synergetic action of microtubules and microfilaments. CB caused the disfigurations of meiotic spindles by interfering the dynamic pattern formation of microtubules and microfilaments, and ultimately inhibited the emission of polar bodies.

Key words: bovine oocyte, cytochalasin B, meiosis, microfilament, microtubule, chromosome