MICROTUBULE ORGANIZATION DURING MATURATION OF XENOPUS OOCYTES - ASSEMBLY AND ROTATION OF THE MEIOTIC SPINDLES
MICROTUBULE ORGANIZATION DURING MATURATION OF XENOPUS OOCYTES - ASSEMBLY AND ROTATION OF THE MEIOTIC SPINDLES
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DOI：
10.1016/0012-1606(92)90190-r
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发表时间：
1992-06-01
影响因子：
2.7
通讯作者：
GARD, DL
中科院分区：
文献类型：
--
作者：
GARD, DL
用荧光共聚焦显微镜和荧光微管蛋白显微注射活卵母细胞的延时共聚焦显微镜观察了甾体酮诱导的Xenopusoacytes成熟过程中减数分裂纺锤体的组装。从一个盘状的MTOC的瞬态微管阵列的组装后不久，观察到芽囊泡破裂。这种MTOC-TMA复合物迅速向动物极迁移，与浓缩的减数分裂染色体有关。在M_1和M_2纺锤体的组装过程中，观察到四个共同的阶段：（1）微管和染色体的紧密聚集体的形成，（2）这种聚集体的重组导致短的双极纺锤体的形成，（3）类似后期B的前中期纺锤体的伸长，相对于卵母细胞A-V轴横向取向，（4）纺锤体的长度和长度的变化。和（4）旋转纺锤体使其与卵母细胞轴对齐。在M1中观察到的纺锤体伸长速率（0.7 μm min−1）比在M2中观察到的（1.8 μm min−1）慢。用antitubulin免疫荧光法检测纺锤体发现许多相互交错的微管，这表明异卵母细胞减数分裂纺锤体的前中期延长是由反平行微管的主动滑动引起的。大量成熟卵母细胞在M1期形成单极微管星状体，由空心球形MTOC成核。随后观察到这些单体发育成双极M1纺锤体并进行减数分裂。本研究结果明确了异种卵母细胞成熟过程中减数分裂纺锤体组装和旋转的复杂途径。
Assembly of the meiotic spindles during progesterone-induced maturation ofXenopusoocytes was examined by confocal fluorescence microscopy using anti-tubulin antibodies and by time-lapse confocal microscopy of living oocytes microinjected with fluorescent tubulin. Assembly of a transient microtubule array from a disk-shaped MTOC was observed soon after germinal vesicle breakdown. This MTOC-TMA complex rapidly migrated toward the animal pole, in association with the condensing meiotic chromosomes. Four common stages were observed during the assembly of both M1 and M2 spindles: (1) formation of a compact aggregate of microtubules and chromosomes; (2) reorganization of this aggregate resulting in formation of a short bipolar spindle; (3) an anaphase-B-like elongation of the prometaphase spindle, transversely oriented with respect to the oocyte A-V axis; and (4) rotation of the spindle into alignment with the oocyte axis. The rate of spindle elongation observed in M1 (0.7 μm min−1) was slower than that observed in M2 (1.8 μm min−1). Examination of spindles by immunofluorescence with antitubulin revealed numerous interdigitating microtubules, suggesting that prometaphase elongation of meiotic spindles inXenopusoocytes results from active sliding of antiparallel microtubules. A substantial number of maturing oocytes formed monopolar microtubule asters during M1, nucleated by hollow spherical MTOCs. These monasters were subsequently observed to develop into bipolar M1 spindles and proceed through meiosis. The results presented define a complex pathway for assembly and rotation of the meiotic spindles during maturation ofXenopusoocytes.