道恩灯塔水母居然可以“长生不老”？

【Para.3】Pulling this trick off does, though, involve a lot of genetic jiggery pokery. And that is the subject of a study just published in the Proceedings of the National Academy of Sciences by Maria Pascual-Torner and Dido Carrero, of Oviedo University, in Spain, and their colleagues. By comparing the genome of T. dohrnii with that of a related, but mortal species, T. rubra, and also studying which genes are active during the process of rejuvenation, they have been able to identify some of the DNA that gives T. dohrnii its age-defying abilities.

【Para.4】Why animals become more decrepit with time, despite having repair mechanisms, is most easily explained by what is known as disposable-soma theory. This starts from the observation that regardless of how well it is maintained throughout the years, an individual organism is one day going to be killed by a predator, a disease, a rival or an accident. Natural selection will therefore favour a successful youth over a successful old age, since the latter may never arrive. Repair is thus good enough, rather than perfect.

【Para.5】The result is that animals which do manage to get old suffer the consequences of their earlier exuberance. These include breakdown of DNA-repair mechanisms, oxidative damage caused as part of the chemical process of respiration, degradation of the structures, called telomeres, that cap a cell’s chromosomes and loss of so-called pluripotent stem cells, which permit the repair of damaged tissues. Rejuvenating this lot is a big project.

【Para.6】To begin their investigation, Dr Pascual-Torner and Dr Carrero identified 1,000 genes from T. dohrnii’s genome that are known, in other species, to regulate aspects of ageing such as those listed above. Comparing these with the genome of T. rubra they identified 28 genes that had different numbers of copies in the two species, and thus, presumably, resulted in different amounts of the proteins they encoded, and also ten unique genetic variants.

【Para.7】These differences suggested that T. dohrnii did indeed invest heavily in DNA replication and repair, in regulating its response to oxidative stress, in repairing telomeres and in maintaining stem-cell pluripotency. Moreover, many of the genes involved were specifically activated during the transition from medusa to polyp.

【Para.8】There were also changes in genes with activities probably related to guiding that metamorphosis. These included genes regulating the tranion of DNA into RNA messenger molecules that carry instructions to a cell’s protein factories, allowing a cell to be reprogrammed, and those governing the way cells communicate with each other, which would be important in the wholesale bodily reshaping that the animal undergoes.

【Para.9】Some of this information may well illuminate understanding of the way human beings age. Though the common ancestor of jellyfish and vertebrates predates the Cambrian period, which began about 540m years ago, many of the genes involved are shared by the two groups, albeit with considerable differences.

【Para.10】That said, rejuvenation of the sort T. dohrnii experiences, which involves the body being largely rebuilt, does seem a rather extreme answer to the question, “would you like to live for ever?

3.单词解析

• undisposable adj. /ˌʌndɪˈspəʊzəb(ə)l/

  not made to be thrown away after use 非一次性的；重复利用的

  （反）disposable gloves/razors 一次性手套 / 剃刀

• soma n. /ˈsəʊmə/ the body of a human being 身体；肉身

• you can/could do worse than do sth

  used to say that you think sth is a good idea 倒不如试做某事；你做某事倒不失可取

  If you want a safe investment, you could do a lot worse than put your money in a building society. 你要想投资而不冒风险，倒不如把钱存到房屋互助协会

• turritopsis dohrnii n

  a small species of jellyfish known for its unique ability to revert back to an earlier life stage through transdifferentiation 灯塔水母

• colloquially adv. /kəˈləʊkwiəli/

  with the use of colloquial expressions 口语地；口头上地

  The people who write parking tickets in New York are known colloquially as “brownies”. 在纽约，开违章停车罚单的人俗称为“棕佬”（brownie）

undisposable adj. /ˌʌndɪˈspəʊzəb(ə)l/

not made to be thrown away after use 非一次性的；重复利用的

（反）disposable gloves/razors 一次性手套 / 剃刀

you can/could do worse than do sth

used to say that you think sth is a good idea 倒不如试做某事；你做某事倒不失可取

If you want a safe investment, you could do a lot worse than put your money in a building society. 你要想投资而不冒风险，倒不如把钱存到房屋互助协会

turritopsis dohrnii n

a small species of jellyfish known for its unique ability to revert back to an earlier life stage through transdifferentiation 灯塔水母

colloquially adv. /kəˈləʊkwiəli/

with the use of colloquial expressions 口语地；口头上地

The people who write parking tickets in New York are known colloquially as “brownies”. 在纽约，开违章停车罚单的人俗称为“棕佬”（brownie）

【来源声明】：本文原文摘选自 The Economist September 3rd 2022 ｜Science & technology，原文版权归杂志所有，仅供个人学习交流使用。

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