Some recent advances in the molecular mechanisms underlying senescence

Aging or senescence is a process in which individuals undergo an exponential decline in vitality, leading to death. Recent years, much progress on the molecular mechanisms underlying senes-cence have been made. (1) Some senescence-related gene such as SEN6A, hic-5, dinl and MORF 4 have been clarified; (2) In 1997, through a set of experiments sponsered scientists of Department of Bi-ology Massachusetts Institute of Technology, it was found that the accommulation of extrachromosomal r DNA circles (ERC) in budding yeast s nucleolus is responsible for cell- senescence and the researchers propose that when enough of these circles accumulate, they clog the nucleus and prevent the cell from reading or eplicating its genome, causing it to stop dividing and ultimately to die; (3) In another work finished National Institute on Aging and the Geron biotech company of Melo, it was proved that a cell s biological clock, which tells the cell how and how many times to divide, lies in its telon eres, little bits of DNA that coat the tips of the chromosome and it was clarified that a powerful enzyme, telomerase, with the potential to rejuvenate the human boss aging tissues could effectively extend the shortened telomere.Although there is a long way to go, scientists still believe that it will be made reality in the future to greatly extend the life-span of human.     

端粒酶与细胞永生化

端粒是真核细胞染色体末端的一种特殊结构,由端粒DNA和端粒蛋白质组成。正常动物细胞DNA的端粒随着细胞分裂而缩短,当缩短到一定长度时细胞将停止增殖并死亡。端粒酶可以从端粒DNA 3′OH末端延伸端粒或合成新的端粒。本文主要介绍了端粒酶的结构和功能以及在细胞永生化中的应用。     

鸡端粒酶结构与功能比较基因组学研究进展

对鸡端粒酶反转录酶基因和蛋白的分子特性以及其结构与功能进行了综述,为鸡端粒酶的深入研究以及其与肿瘤发生的相关性研究提供参考.     

Highly characteristic and individual specific telomere length patterns in cattle

A combined primed in situ labelling (PRINS)/4',6-diamino-2-phenylindole (DAPI)/propidium iodide (PI)-fluorescence-banding method was used to characterise telomeres, identify their specific chromosomes and visualise neighbouring heterochromatin in 25 artificial insemination (AI) bulls. A highly heterogeneous telomere length pattern was found in cattle. Each bull possessed his own characteristic, specific telomere length pattern.     

端粒及其研究进展

端粒是真核生物染色体末端的一种特殊结构,由端粒DNA和端粒相关蛋白组成,它能维持染色体的结构稳定和功能,保护其免受核酸酶降解,防止其末端融合或重排等。端粒长度的维持机制主要有ALT机制和TA机制。端粒长度的维持以及端粒酶的利用在衰老的控制中起重要作用。本文在系统论述端粒的结构、端粒的维持机制以及端粒与衰老的关系等研究进展的基础上,就当前该研究领域中存在的问题提出了个人的观点。     

四种树木端粒酶活性与树龄及叶位的相关性

为探究端粒酶活性与树龄以及叶位是否存在一定的关系，应用TRAP法对不同年龄的油松、银杏、楸树、国槐叶片及油松和银杏同一棵树不同叶位的叶片进行端粒酶活性的测定。结果表明，油松端粒酶活性同树龄无明确的相关性，而楸树、国槐的端粒酶活性随着树龄增加而表现为增加的趋势。端粒酶活性与叶位相关，越靠近顶端的叶片端粒酶活性较高，而靠近下端的叶片端粒酶活性较低。     

年龄推测的分子生物学方法

年龄结构是研究种群动态的重要基础。本文介绍了有别于传统形态学方法鉴定动物年龄的3类估计年龄的分子生物学方法;1）氨基酸构型比与年龄正相关分析法;2）端粒平均长度与年龄负相关分析法;3）DNA损伤或与蛋白质交联程度与年龄相关分析法。详细阐述了这些方法在实际工作中的适用对象、应用条件、方法和原理。并对野生动物年龄推断的研究方法进行了展望。