摘要
This paper investigated the age-related changes in the expression patterns of maintenance methyltransferase (DNMT1) and de novo methyltransferases (DNMT3a, 3b, 3L) and the chromosome architecture in in-vivo matured mouse oocytes using two-photon laser-scanning microscope. Our results showed that (1) DNMT1 and DNMT3a, 3b, 3L in the oocytes of pubertal mice were located in the cortical region of oocyte cytoplasm. In aging groups, DNMT1 was also located in the cortical region. However, DNMT3a, 3b, 3L had a relatively wider distribution in the oocyte cytoplasm and appeared near the chromosomes. These differences between pubertal and aging groups suggested that aging might affect DNA methylation; (2) the expression of DNMT1, and DNMT3a, 3b in aging groups increased significantly compared to pubertal groups, while, the expression of DNMT3L decreased. These results might be explained by the compensation mechanism among DNMTs, which might be impervious to aging; (3) aging caused increased errors in the distribution and three-dimensional morphology of chromosomes, including the increased total volume and surface area, the high ratio of height to diameter of a circular cylinder enclosing the chromosomes (H/D). Our work provided morphological information for the studies of age-related decline in oocyte qualities.
This paper investigated the age-related changes in the expression patterns of maintenance methyltransferase （DNMT1） and de novo methyltransferases （DNMT3a, 3b, 3L） and the chromosome architecture in in-vivo matured mouse oocytes using two-photon laser-scanning microscope. Our results showed that （1） DNMT1 and DNMT3a, 3b, 3L in the oocytes of pubertal mice were lo- cated in the cortical region of oocyte cytoplasm. In aging groups, DNMT1 was also located in the cortical region. However, DNMT3a, 3b, 3L had a relatively wider distribution in the oocyte cytoplasm and appeared near the chromosomes. These differ- ences between pubertal and aging groups suggested that aging might affect DNA methylation; （2） the expression of DNMT1, and DNMT3a, 3b in aging groups increased significantly compared to pubertal groups, while, the expression of DNMT3L decreased. These results might be explained by the compensation mechanism among DNMTs, which might be impervious to aging; （3） aging caused increased errors in the distribution and three-dimensional morphology of chromosomes, including the increased total vol- ume and surface area, the high ratio of height to diameter of a circular cylinder enclosing the chromosomes （H/D）. Our work pro- vided morphological information for the studies of age-related decline in oocyte qualities.
基金
supported by the National Natural Science Foundation of China (90919012 and 10874099)
National Basic Research Program of China (2007CB5119004)
the Doctoral Program Research Fund of the Chinese Ministry of Education (20090002110065)
the Tsinghua University Initiative Scientific Research Program (2010THZ01)
