無病無痛,沒有任何交通或人為意外的話,人類是否會進入不死永生狀態呢?678Please respect copyright.PENANA4PzQXD3Psb
678Please respect copyright.PENANAxA9nY2T4R6
答案是,不會。678Please respect copyright.PENANApPQybm7HkZ
678Please respect copyright.PENANAgEsTFOPa7V
箇中的原因,就是在於染色體亦即是DNA的運作機制之上。678Please respect copyright.PENANAs9Z3CGewbu
678Please respect copyright.PENANASLYJVPKsOF
678Please respect copyright.PENANALjhxuFM2Oi
(圖1)正常人體細胞分裂的時候,染色體的長度會越來越短。678Please respect copyright.PENANAvPQkpB6vIt678Please respect copyright.PENANAb6lmZhNdsF
678Please respect copyright.PENANAHXqX1af9Vi
678Please respect copyright.PENANAm58qOGf3hx
(圖2)染色體的頂端區域,我們稱之為Telomere。正常細胞分裂後,Telomere的長度便會越來越短,所以導致染色體的總長度亦會有所減少。678Please respect copyright.PENANALN6x4wWZuO678Please respect copyright.PENANAQfqG8YHnmG
678Please respect copyright.PENANAtnhpyHPdTf
(圖3)而幹細胞進行分裂的時候,則會有著Telomerase的協助,導致Telomere的長度便並不會有所減少。678Please respect copyright.PENANAurQPKXdLlW
然而,當幹細胞變成正常細胞後,Telomerase的功能便會消失。678Please respect copyright.PENANAQVBE4vWYxe678Please respect copyright.PENANA6cAiDPH5tD
678Please respect copyright.PENANAo4TpA86WVN
678Please respect copyright.PENANAiogMIm13yN
(圖4)當Telomere長度削減到一定程度的時候,細胞便會自行啟動機制滅亡,又或者陷入衰老(Senescence)狀態。678Please respect copyright.PENANA3fqtxcHwUN
678Please respect copyright.PENANA7TLvMraL7j
細胞滅亡或衰老的話,器官的功能便會衰退,最後亦會支撐不住,無法正常運作,促成死亡。678Please respect copyright.PENANAXvcOck7yM9678Please respect copyright.PENANAXDMZlZrMoB
678Please respect copyright.PENANAHQ0Eou82ql
你可能會問,現在科技如此倡明,那麼我們只要學習幹細胞的那一套方式,動用外力重啟Telomerase功能,那不就能踏入永生嗎?678Please respect copyright.PENANAcdPhqgXT37
678Please respect copyright.PENANANETMQ94w4b
這個思路並沒有錯,只不過代價就是會增加患癌的風險。678Please respect copyright.PENANA4QGYVAMd8b
678Please respect copyright.PENANAtZvoDbMrRE
事實上,不少癌細胞的特徵就是Telomere長度非常之短,但又有著一定水平的Telomerase功能穩定維持著Telomere的長度,逃避進入滅亡的命運。678Please respect copyright.PENANAmTqIurSROR
678Please respect copyright.PENANAaymoa3JVx2
另一方面的想,如果細胞真的是踏入「永生」狀態的話,終有一天無可避免會累積各種的DNA變異,促成癌細胞的誕生。678Please respect copyright.PENANAy1j1s9sOrY
678Please respect copyright.PENANAGcmyeIzlnU
(圖5)既然Telomere對細胞的壽命有著重要影響的話,那麼一些較為長壽的物種是否擁有較長的Telomere呢?678Please respect copyright.PENANAW7h9Rho1IL
678Please respect copyright.PENANAFhL58XKTZA
科學家比較各物種的Telomere後(Ref1),發現海豚的起始Telomere長度比人類高出6倍以上,但壽命長度始終是人類佔優。678Please respect copyright.PENANARqasKJLLu2678Please respect copyright.PENANAL0JDl5SjDU
678Please respect copyright.PENANAm74tdL9yNT
反而,決定物種壽命長度的其中一種因素,則是Telomere衰減的速度;678Please respect copyright.PENANA35vILYuROg
Telomere衰減的速度只是一個參考性的指標,並非絕對。物種的大小、新陳代謝機制的不同等等均會對壽命長度有著影響。678Please respect copyright.PENANAlhm0uDwvhg
678Please respect copyright.PENANABILBnkKJPO
人類每年約會減少71單位Telomere的長度,最高壽命為120歲。678Please respect copyright.PENANAtcjuXupltE
而老鼠每年會減少7000單位Telomere長度,最高壽命為5歲。678Please respect copyright.PENANAjULWHMue25
678Please respect copyright.PENANAVGMzJiGWZK
人類:每年減少71;120歲678Please respect copyright.PENANAa4zdihoC99
大象:每年減少109;66歲678Please respect copyright.PENANArSsflnyiYX
紅鸛:每年減少105;60歲678Please respect copyright.PENANA9kNGqYqspq
海豚:每年減少766;52歲678Please respect copyright.PENANAq7CyEuQddx
兀鷲:每年減少209;41歲678Please respect copyright.PENANAhQVpH4gVHw
海鷗:每年減少771;25歲678Please respect copyright.PENANAFZlEhvB6fI
馴鹿:每年減少531;22歲678Please respect copyright.PENANAPV9VK5OZ5y
山羊:每年減少363;21歲678Please respect copyright.PENANAB7mwKDQdCO
老鼠:每年減少7000;5歲678Please respect copyright.PENANAgWDRrBvFmO
678Please respect copyright.PENANAeq6W7uxqYo
678Please respect copyright.PENANAVMgUEaAFsw
龜又是每年減少幾多呢?有待有心人發掘。678Please respect copyright.PENANAis3KEQs6zP
678Please respect copyright.PENANAXVF7AbEE14
678Please respect copyright.PENANAYxvcY69Hf0
如果想我快啲出文的話,請入去Penana網站科普專欄–薯不揀單俾一個like以及Bookmark,這對我非常之重要。678Please respect copyright.PENANAqVFELiYJfW
678Please respect copyright.PENANAH5W4LINRiJ
Link: https://www.penana.com/story/66244/%E7%A7%91%E6%99%AE%E5%B0%88%E6%AC%84-%E8%96%AF%E4%B8%8D%E6%8F%80%E5%96%AE/toc678Please respect copyright.PENANA9bSee8HZtw
678Please respect copyright.PENANArOkWbcGlGs
同時亦可以在Penana網站裡按「買一嚿/半嚿薯仔」,以課金的方式推動我繼續搜羅資料寫文,多謝。678Please respect copyright.PENANARkCC3JQQdb
678Please respect copyright.PENANAphXIxSodQt
Link:678Please respect copyright.PENANAP378qvXjvh
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio678Please respect copyright.PENANADvYBCeEYva
678Please respect copyright.PENANAiw0tXidADQ
678Please respect copyright.PENANAZQICB1ajEW
有興趣接收科學資訊的話,歡迎follow IG: potatopigtongue。678Please respect copyright.PENANAtcukvArvZK
678Please respect copyright.PENANA3bmPrHuPg4
678Please respect copyright.PENANA4IB8PoxzP7
Ref1:https://www.pnas.org/content/116/30/15122678Please respect copyright.PENANACWi610VMXq