人体的衰老机制有可能人为减缓？科学家在最近的研究中发现了一些可能潜藏在干细胞中的“青春之源”，它们是如何被发现的？发现的意义在哪里？跟着托福小编一起开始今天的托福阅读学习吧。
阅读之前先来学习一下文章中的疑难词吧：
Fountain n. 喷泉，泉水；源泉
stem n. 干；茎v阻止，起源
perish vi. 死亡；毁灭
stressed-out adj. 不堪重负的；承受巨大压力的
Rejuvenate vt. 使年轻；使更新原vi. 复原；变年轻
confirm vt. 确认；确定；证实
Multitude n. 群众；多数
boost n. 推动；帮助；宣扬v. 宣扬；促进
awry adj. 错误的
kick in把…踢进去：踢开
unwind v 放松；解开
submitvi. 提交；服从vt. 使服从；主张
expertise n. 专门知识；专门技术
insight n. 洞察力；洞悉
clinical adj. 临床的；诊所
quiescent adj. 静止的；不活动的
regeneration n.再生，重生
开始读文章：
Fountain of youth might hide in "relaxed" stem cells
“青春之源”可能潜藏在“放松的”干细胞中
相关知识：
应激水平：所谓应激是机体在各种内外环境因素及社会、心理因素刺激时所出现的全身性非特异性适应反应，又称为应激反应。这些刺激因素称为应激源。应激是在出乎意料的紧迫与危险情况下引起的高速而高度紧张的情绪状态。应激的最直接表现即精神紧张。指各种过强的不良刺激，以及对它们的生理、心理反应的总和。
应激反应指所有对生物系统导致损耗的非特异性生理、心理反应的总和。应激或应激反应是指机体在受到各种强烈因素(应激源)刺激时所出现的非特异性全身反应。
High stress levels can have a critical impact not only on the surface, making our skin age, but also on a molecular level, when stressed cells cannot cope with the pressure and perish much faster than the ones who can.
高应激水平不仅使人体皮肤处于危险状态：加速皮肤衰老；而且在分子水平上也有危害：当应激细胞无法防御时，会比那些可防御细胞更快凋亡。
In a new research released on Thursday, scientists at the University of California, Berkeley, analyzed blood stem cells and found out that the cell's ability to repair damage in the mitochondria, their power source, was critical to their survival. Researchers tried to "relax" these stressed-out cells by slowing down the activity of their mitochondria.
在周四新发表的研究结果中，加州大学伯克利分校的科学家分析了造血干细胞，并发现细胞在线粒体内的自我修复能力，能量来源对细胞能否存活至关重要。研究者们试图通过制约线粒体活动来使这些应激细胞“放松”。
"We found that by slowing down the activity of mitochondria in the blood stem cells of mice, we were able to enhance their capacity to handle stress and rejuvenate old blood. This confirms the significance of this pathway in the aging process," said Danica Chen, an assistant professor with the Department of Nutritional Sciences and Toxicology.
营养科学和毒理学助理教授丹妮卡.陈表示，“我们发现，制约老鼠造血干细胞中的线粒体活动，确实可以增强老鼠细胞应激能力和更新血液的能力。”
This pathway lies mainly in the multitude of proteins that need to be folded properly for the mitochondria to function correctly. When the folding goes awry, the mitochondrial unfolded-protein response, or UPRmt, kicks in to boost the production of specific proteins to fix or remove the misfolded protein.
这种路径主要存在于大多数需要正确折叠以使线粒体保持正常功能的蛋白质中。如果蛋白质空间折叠出现错误，会出现蛋白质展开反应(或者简称UPRmt)，推动细胞生成特定蛋白修复或者除去折叠错误的蛋白质。
Researchers found that certain protein known as SIRT7 helps cells cope with the stress of unfolding the proteins in the mitochondria, helping those with higher levels of SIRT7 survive longer by making them "unwind." But the levels of SIRT7 decrease as people age.
研究者发现，一种名为SIRT7的非特异性免疫分子可以帮助细胞应对来非折叠蛋白的压力，通过使其放松帮助那些有着更高SIRT7水平的细胞存活得更久。
"The protein level decreases as years go by," Chen said. "But if we increase this protein in blood stem cells we can make them live longer. Cells in general don't just die suddenly；they are submitted to high stress levels and lose their functions with age."
陈还说，“这种蛋白质水平会随时间降低，但是如果我们人为增加它在造血干细胞中的水平，我们可以使它们存活时间更长。一般情况下，细胞不会无缘无故地凋亡，而是因为它们处于高应激水平然后随时间机能减退。”
Chen does not want to encourage the thought that she and other researchers have found the "fountain of youth," but more of a new path for study.
陈并不觉得她和其他研究人员发现了“青春之泉”,而是更多地把它看做是一种新的研究路径。
"We still don't know if this would work on other kinds of stem cells, such as pancreatic stem cells or heart cells, and we don't have any expertise with those tissues, so we would be very happy to collaborate with other laboratories to tackle the matter," she said.
“我们仍然不知道这样的结论是不是适用于其他类型的干细胞，比如胰腺干细胞或者心脏细胞，而且我们没有关于这些组织的专业知识，所以如果可以和其他实验室合作来解决这些问题我们会很荣幸。”
The study, published Thursday in the Science journal, is expected to help researchers gain more insight into the aging process, and even slow it down.
周四发布在科学杂志上的这项研究结果预计可以使相关研究者获得对衰老过程更多的认识，甚至可以使他们找到减速衰老的方法。
"Maybe in the future, once we are done with the clinical trial on humans and we can prove this research on other body stem cells, we will be able to produce a drug that can slow down this process by addressing this specific pathway," she said, adding that most likely that will not be in the near future.
陈还说，“未来一旦我们完成了临床试验并证明了这项研究适用于其他类型人体干细胞，我们应该可以开发出一种通过利用研究中的路径来减速衰老过程的药物，当然这应该不会太早实现。”
Until this study, it was unclear which stress signals regulate the transition of stem cells to and from the quiescent mode, and how that relates to tissue regeneration in the aging process.
通过这项研究还没有确定控制干细胞从静态模式间转化的压力信号，以及这些信号和衰老过程的组织再生有何关联。
If the study is on the right track and this pathway can be applied to other stem cells, humans would not only be able to live longer, but would also stay young and healthy for most of that time.
即使这项研究完全正确，这样的路径也适合其他干细胞，人类也不可能因此更长寿，但是可以一直保持年轻、健康。
文章中的长难句：
Chen does not want to encourage the thought( that she and other researchers have found the "fountain of youth,") but more of a new path for study.
句子类型：定语从句
句子拆分：
主干：Chen does not want to encourage the thought…
定语从句：that she and other researchers have found the "fountain of youth"，修饰thought but more of a new path for study，可能很难看出这部分是什么成分，其实同义表达是：
Chen does not want to encourage the thought that she and other researchers have found the "fountain of youth," but (that she and other researchers have found a new path for study).
翻译：陈并不觉得她和其他研究人员发现了“青春之泉”,而是更多地把它看做是一种新的研究路径。
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