Telomerase activity in female and male rat germ cells undergoing meiosis and in early embryos
Telomerase activity in female and male rat germ cells undergoing meiosis and in early embryos
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DOI：
10.1095/biolreprod56.5.1120
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发表时间：
1997-05-01
影响因子：
3.6
通讯作者：
Hsueh, AJW
中科院分区：
文献类型：
--
作者：
Eisenhauer, KM;Gerstein, RM;Hsueh, AJW
端粒酶是一种在真核染色体末端合成端粒DNA的核糖核蛋白。据推测，端粒酶活性是细胞永生化所必需的，并且端粒酶活性存在于生殖系来源的细胞中。本研究的目的是测定以下大鼠细胞中端粒酶活性的水平：1）不同发育阶段卵泡的卵母细胞，2）生精细胞，3）早期胚胎。端粒酶活性定量使用最近开发的，敏感的聚合酶链反应为基础的测定和人肾细胞系（293）作为标准。端粒酶活性在早期窦卵泡和排卵前卵泡的卵母细胞中发现，以及在排卵卵母细胞。早期窦卵泡和排卵前卵泡中的酶活性水平与293细胞的酶活性水平相当，而排卵卵母细胞中的酶活性水平低50倍。粗线期精母细胞和圆形精子细胞中端粒酶活性更低，附睾头和尾部精子中均未检测到端粒酶活性。受精后，端粒酶活性在4-细胞胚胎中存在。端粒酶活性也检测到几个大鼠体组织。这些数据表明，端粒酶活性存在于生殖细胞的几个阶段的分化，与精子，并建议端粒酶活性可能是重要的减数分裂过程中。单个卵母细胞中高水平的端粒酶活性可以作为监测激素、衰老和毒素对卵母细胞质量影响的标志。
Telomerase is a ribonucleoprotein that synthesizes telomeric DNA at the ends of eukaryotic chromosomes. It has been hypothesized that telomerase activity is necessary for cellular immortalization and that telomerase activity is present in cells of germline origin. The objective of the present study was to determine the level of telomerase activity in the following rat cells: 1) oocytes from follicles at different stages of development, 2) spermatogenic cells, and 3) early embryos. Telomerase activity was quantitated using a recently developed, sensitive polymerase chain reaction-based assay and a human kidney cell line (293) as a standard. Telomerase activity was found in oocytes from early antral and preovulatory follicles, as well as in ovulated oocytes. The level of enzyme activity in early antral and preovulatory follicles was comparable to that of the 293 cells, while levels in ovulated oocytes were 50-fold lower. Telomerase activity was present in even lower levels in pachytene spermatocytes and round spermatids, and no telomerase activity was detected in spermatozoa from either the caput or the cauda epididymis. After fertilization, telomerase activity was present in 4-cell embryos. Telomerase activity was also detected in several rat somatic tissues. These data demonstrate that telomerase activity is present in germ cells at several stages of differentiation, with the exception of spermatozoa, and suggest that telomerase activity may be important during meiosis. The high levels of telomerase activity in individual oocytes may serve as a marker for monitoring the effects of hormonal agents, aging, and toxins on oocyte quality.