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?536Please respect copyright.PENANAVXEJNX46lR
536Please respect copyright.PENANAY2pyO9lnsA
答案是,不會。536Please respect copyright.PENANAnJrGkJsdUX
536Please respect copyright.PENANABe9uHS2fW8
箇中的原因,就是在於染色體亦即是DNA的運作機制之上。536Please respect copyright.PENANA2DTAcS10cG
536Please respect copyright.PENANA8Vur2hCV3Q
536Please respect copyright.PENANAcxNPhLbkrx
(圖1)正常人體細胞分裂的時候,染色體的長度會越來越短。536Please respect copyright.PENANARKYaLEy0tx536Please respect copyright.PENANAoIT1zY7skP
536Please respect copyright.PENANAxr5fLEgrwC
536Please respect copyright.PENANAkQSgIu5rfX
(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。536Please respect copyright.PENANAJ4V0YkTK9E536Please respect copyright.PENANA4yoqntgX86
536Please respect copyright.PENANAG2nX0gf0EG
(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。536Please respect copyright.PENANAD2mD5AmwH7
然而,當幹細胞變成正常細胞後,Telomerase的功能便會消失。536Please respect copyright.PENANA3AeuG7XNS9536Please respect copyright.PENANASeLS0SKTGg
536Please respect copyright.PENANANxTQCqmCzo
536Please respect copyright.PENANAFzWKSBUvil
(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。536Please respect copyright.PENANAPRypoPy5Ge
536Please respect copyright.PENANAxI8PujL3QP
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。536Please respect copyright.PENANAt9IFaonEXE536Please respect copyright.PENANAhUkFnRyAVX
536Please respect copyright.PENANA80SZvQYYeH
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?536Please respect copyright.PENANA9dgmGFjl5F
536Please respect copyright.PENANA0aJYyXujXD
這個思路並沒有錯,只不過代價就是會增加患癌的風險。536Please respect copyright.PENANAu8E4vg3tFY
536Please respect copyright.PENANAdLymIFib2H
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。536Please respect copyright.PENANAvD1t5RybyD
536Please respect copyright.PENANA0of2ms46Rm
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。536Please respect copyright.PENANA0dsDNEnBly
536Please respect copyright.PENANAOIvsfdyDLM
(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?536Please respect copyright.PENANAThQ4Cc6pnU
536Please respect copyright.PENANAdVCYo4oRML
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。536Please respect copyright.PENANAwEwF7RlmUj536Please respect copyright.PENANAz4uzR8WAo9
536Please respect copyright.PENANA33FptAY9tH
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;536Please respect copyright.PENANAxeQUknZOUi
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。536Please respect copyright.PENANA6mJ9FaL85U
536Please respect copyright.PENANAxaMHadkSzb
人類每年約會減少71單位Telomere的長度,最高壽命為120歲。536Please respect copyright.PENANAvSbX6L4Fp6
而老鼠每年會減少7000單位Telomere長度,最高壽命為5歲。536Please respect copyright.PENANA5RTsvsfMu0
536Please respect copyright.PENANAdJMPZZE5d2
人類:每年減少71;120歲536Please respect copyright.PENANAq0XvPxLzre
大象:每年減少109;66歲536Please respect copyright.PENANAbN0OEFFcjZ
紅鸛:每年減少105;60歲536Please respect copyright.PENANARKoFEDwaOH
海豚:每年減少766;52歲536Please respect copyright.PENANA2BqCblsVz9
兀鷲:每年減少209;41歲536Please respect copyright.PENANAcvT9BQD0pq
海鷗:每年減少771;25歲536Please respect copyright.PENANAh0O4ZzouwD
馴鹿:每年減少531;22歲536Please respect copyright.PENANAitS5VJVgdQ
山羊:每年減少363;21歲536Please respect copyright.PENANApxILydUaD2
老鼠:每年減少7000;5歲536Please respect copyright.PENANARegUxr9dNj
536Please respect copyright.PENANAKJsPX4MQX3
536Please respect copyright.PENANAHIy6q197qP
龜又是每年減少幾多呢?有待有心人發掘。536Please respect copyright.PENANA1WEmaQwgRb
536Please respect copyright.PENANAyVJS8c9qwg
536Please respect copyright.PENANAH9n2hQ0J8E
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。536Please respect copyright.PENANAiBBcr0Rqmk
536Please respect copyright.PENANAsA4JdkIRFL
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/toc536Please respect copyright.PENANAKQlQa1MC1f
536Please respect copyright.PENANAbze56S8pbT
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。536Please respect copyright.PENANAzjhdMEhhx5
536Please respect copyright.PENANA5IWqam8bpp
Link:536Please respect copyright.PENANAX2dvz5VYgc
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio536Please respect copyright.PENANAROncZFm6d7
536Please respect copyright.PENANAci9LnDX0TW
536Please respect copyright.PENANApt360OtAGX
有興趣接收科學資訊的話,歡迎follow IG: potatopigtongue。536Please respect copyright.PENANAemFQsIHb9N
536Please respect copyright.PENANAE1fzqFvynT
536Please respect copyright.PENANAFF3hJ80cOV
Ref1:https://www.pnas.org/content/116/30/15122536Please respect copyright.PENANAmV803O3Iy6