Wang Jun-Zuo, Sui Hong-Shu, Miao De-Qiang, Liu Na, Zhou Ping, Ge Li, Tan Jing-He
Laboratory for Animal Reproduction and Embryology, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Shandong Province, People's Republic of China.
Reproduction. 2009 Feb;137(2):181-9. doi: 10.1530/REP-08-0339. Epub 2008 Nov 24.
The objectives of this study were to investigate the effect of heat stress during in vitro maturation on the developmental potential of mouse oocytes and to determine whether the deleterious effect was on the nuclear or cytoplasmic component. While rates of oocyte nuclear maturation (development to the metaphase II stage) did not differ from 37 to 40 degrees C, rates for blastocyst formation decreased significantly as maturation temperature increased from 38.5 to 39 degrees C. Chromosome spindle exchange showed that while blastocyst formation did not differ when spindles matured in vivo or in vitro at 37, 40 or 40.7 degrees C were transplanted into in vivo matured cytoplasts, no blastocyst formation was observed when in vivo spindles were transferred into the 40 degrees C cytoplasts. While oocytes reconstructed between 37 degrees C ooplasts and 37 or 40 degrees C karyoplasts developed into 4-cell embryos at a similar rate, no oocytes reconstituted between 40 degrees C ooplasts and 37 degrees C spindles developed to the 4-cell stage. Immunofluorescence microscopy revealed impaired migration of cortical granules and mitochondria in oocytes matured at 40 degrees C compared with oocytes matured at 37 degrees C. A decreased glutathione/GSSG ratio was also observed in oocytes matured at 40 degrees C. While spindle assembling was normal and no MAD2 was activated in oocytes matured at 37 or 40 degrees C, spindle assembling was affected and MAD2 was activated in some of the oocytes matured at 40.7 degrees C. It is concluded that 1) oocyte cytoplasmic maturation is more susceptible to heat stress than nuclear maturation, and 2) cytoplasmic rather than nuclear components determine the pre-implantation developmental capacity of an oocyte.
本研究的目的是调查体外成熟过程中的热应激对小鼠卵母细胞发育潜力的影响，并确定有害影响是作用于细胞核还是细胞质成分。虽然卵母细胞核成熟率（发育至中期II期）在37至40摄氏度之间没有差异，但随着成熟温度从38.5摄氏度升高到39摄氏度，囊胚形成率显著下降。染色体纺锤体交换显示，当在37、40或40.7摄氏度下体内或体外成熟的纺锤体移植到体内成熟的细胞质体中时，囊胚形成没有差异，但当体内纺锤体转移到40摄氏度的细胞质体中时，未观察到囊胚形成。虽然在37摄氏度的卵质体和37或40摄氏度的核质体之间重建的卵母细胞以相似的速率发育成4细胞胚胎，但在40摄氏度的卵质体和37摄氏度的纺锤体之间重建的卵母细胞没有发育到4细胞阶段。免疫荧光显微镜显示，与在37摄氏度成熟的卵母细胞相比，在40摄氏度成熟的卵母细胞中皮质颗粒和线粒体的迁移受损。在40摄氏度成熟的卵母细胞中还观察到谷胱甘肽/氧化型谷胱甘肽比值降低。虽然在37或40摄氏度成熟的卵母细胞中纺锤体组装正常且没有MAD2被激活，但在40.7摄氏度成熟的一些卵母细胞中纺锤体组装受到影响且MAD2被激活。得出的结论是：1）卵母细胞的细胞质成熟比核成熟更容易受到热应激的影响；2）细胞质而非细胞核成分决定了卵母细胞植入前的发育能力。
