Gilchrist G C, Kurjanowicz P, Mereilles F V, King W A, LaMarre J
Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada.
Reprod Domest Anim. 2015 Feb;50(1):58-67. doi: 10.1111/rda.12449. Epub 2014 Dec 3.
Telomeres are specialized structures that cap the ends of chromosomes and help to maintain genomic integrity and stability. Telomeres undergo dynamic changes during embryo development, which also represents an important stage for telomere elongation through telomerase enzyme activity. The objectives of this study were to examine changes in telomere length and telomerase activity from the early oocyte, through to the blastocysts stage of development, and the expression of factors with the potential to directly regulate telomeres. In vitro-produced bovine embryos were lysed and analysed for either relative telomere length, or telomerase activity using quantitative real-time PCR protocols. Our results reveal that relative telomere length is the shortest in the presumptive zygote stage of development and gradually increases to the blastocyst stage. We also demonstrate that differences between the mean telomere lengths throughout these stages are statistically significant (p < 0.05). Telomerase activity in the stages examined appears relatively constant until the blastocyst, where the highest level of activity is detected, leading to a significant difference in telomerase activity across embryonic stages (p < 0.005). Bovine telomerase RNA component (bTERC) expression levels were highest in the blastocyst, TERF1 transcripts showed little change in expression, and TERF2 expression decreased in the blastocysts (p < 0.05). Our results suggest that a complex integration of telomere-related RNA and proteins influences the regulatory mechanisms involved in 'reprogramming' of telomeres during early embryonic stages.
端粒是位于染色体末端的特殊结构，有助于维持基因组的完整性和稳定性。端粒在胚胎发育过程中会发生动态变化，这也是通过端粒酶活性实现端粒延长的重要阶段。本研究的目的是检测从早期卵母细胞到囊胚发育阶段端粒长度和端粒酶活性的变化，以及直接调控端粒的相关因子的表达。对体外生产的牛胚胎进行裂解，使用定量实时PCR方法分析相对端粒长度或端粒酶活性。我们的结果显示，相对端粒长度在假定合子期发育阶段最短，并逐渐增加至囊胚阶段。我们还证明，这些阶段的平均端粒长度差异具有统计学意义（p < 0.05）。在所检测的阶段中，端粒酶活性直到囊胚阶段之前都相对恒定，而在囊胚阶段检测到最高水平的活性，导致胚胎各阶段的端粒酶活性存在显著差异（p < 0.005）。牛端粒酶RNA组分（bTERC）的表达水平在囊胚中最高，TERF1转录本的表达变化不大，而TERF2在囊胚中的表达下降（p < 0.05）。我们的结果表明，端粒相关RNA和蛋白质的复杂整合影响了早期胚胎阶段端粒“重编程”所涉及的调控机制。
