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一项新研究从194岁巨龟Jonathan的基因与化学标记中寻找长寿线索。文章沿着研究方法、主要发现和样本限制，说明为什么这些线索还不能直接变成人类长寿结论。

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Jonathan, an Aldabra giant tortoise, is about 194 years old. He is the oldest known living land animal with strong records to support his age. A new study asks a simple question: why has he lived so long? The answer may involve both his genes and the way his body still controls some important genes. However, the researchers are careful not to call either one the full cause.

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阿尔达布拉象龟Jonathan约194岁，是目前有可靠记录支持的、已知最长寿的在世陆生动物。一项新研究提出了一个简单问题：它为何如此长寿？答案可能既与它的基因有关，也与身体仍能控制某些重要基因的方式有关。不过，研究人员谨慎地没有把任何一项因素称为全部原因。

Jonathan lives on Saint Helena, a small island in the South Atlantic. He arrived there in 1882 as a fully grown animal, which means he was already about 50. For the study, scientists collected cells from inside his mouth. They then read his genome, the complete set of DNA instructions, and his epigenome. The epigenome includes chemical marks that help switch genes on or off.

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Jonathan生活在南大西洋的小岛圣赫勒拿岛。1882年抵达那里时，它已经完全成年，这意味着当时约有50岁。研究人员从它的口腔内采集细胞，随后读取其基因组——一套完整的DNA指令——以及表观基因组。表观基因组包含帮助开启或关闭基因的化学标记。

The team found 287 gene changes that were not seen in the other giant tortoises used for comparison. Some were connected with DNA repair, cancer control, insulin regulation and the protective ends of chromosomes. Jonathan also had extra copies of a gene linked to removing old or dangerous cells. These findings fit several known paths related to long life, but they do not show that one change kept him alive.

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研究团队发现了287种在用于比较的其他巨龟中未见的基因变化。其中一些与DNA修复、癌症控制、胰岛素调节和染色体末端保护有关。Jonathan还拥有某个与清除衰老或危险细胞有关的基因的额外副本。这些发现符合几条已知的长寿相关路径，但不能证明是某一种变化让它活到了现在。

The chemical marks offered another clue. As animals grow older, these marks often become less orderly. Researchers call this growing disorder methylation entropy. Most parts of Jonathan’s epigenome looked as old as expected. Yet around some genes that help cells produce energy, the pattern was unusually orderly. In those places, it was more like the pattern found in a five-year-old tortoise than in older adults.

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化学标记提供了另一条线索。动物衰老时，这些标记通常会变得更加无序。研究人员将这种不断增加的混乱称为甲基化熵。Jonathan表观基因组的大部分区域都呈现出符合其年龄的样子，但在一些帮助细胞产生能量的基因周围，标记模式却异常有序。在这些区域，它更像一只5岁的幼龟，而不是年长的成年龟。

This result may matter because cells need steady energy to repair damage and continue working. If the switches around energy genes remain clear, those genes may keep doing their jobs well for longer. Similar patterns have appeared in studies of very old people. That does not mean tortoise biology can be copied directly into humans, but it gives scientists a possible path for future research.

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这一结果可能很重要，因为细胞需要稳定的能量来修复损伤并继续工作。如果能量相关基因周围的“开关”保持清晰，这些基因或许能在更长时间内正常发挥作用。对非常长寿的人类所做的研究中也出现过相似模式。这并不表示象龟的生物机制可以直接复制到人类身上，但它为未来研究提供了一条可能的路径。

There are also important limits. Jonathan was compared with only four other Aldabra tortoises, and he is a single unusual animal. His tropical home, carefully controlled food and medical care may also have helped him. The study therefore offers clues, not a proven formula for a longer life. Its value is showing which parts of ageing biology deserve closer tests in larger groups.

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研究也存在重要限制。Jonathan只与另外四只阿尔达布拉象龟进行了比较，而且它本身是一个特殊的单一个体。热带居住环境、受到严格管理的食物和医疗照护也可能帮助了它。因此，这项研究提供的是线索，而不是已经得到证实的长寿公式。它的价值在于指出了衰老生物学中哪些部分值得在更大群体中进一步检验。

新闻来源

Reuters · A 194-year-old tortoise, world’s oldest land animal, may hold clues to longer life

EL PAÍS · La tortuga ‘Jonathan’ tiene 194 años y en sus genes se esconden los secretos de la longevidad

Science Advances · Epigenomic insights into extreme longevity in the world’s oldest terrestrial animal, Jonathan

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