Transcript 課堂簡報
生命為什麼如此複雜? 周成功 104年10月5日 這些無數繁複的生命形式從何而來 ？ Charles Darwin (Feb. 12, 1809 – Apr. 19,1882) “Probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed,” Darwin: On the Origin of Species (1859) 天生萬物都來自一個共同的祖先？ 是的！我們都來自一個共同的祖先！ 生命怎麼變的如此複雜? 生物演化的三步曲：變異、遺傳與天擇 生物演化的三步曲：變異、遺傳與天擇 遺傳資訊 (genotype) 的變異 變異 蛋白質胺基酸序列的改變 遺傳 蛋白質結構與功能的改變 生命表徵 (phenotype) 的改變 對環境改變時的適應力：天擇 細胞的演化 • LUCA:第一個原核細胞 (prokaryotes) –Bacteria –Archaeal – 如何從環境中取得食物? LUCA Tree of life (based on 16S rRNA sequences) How bacteria and archaeal diverged from LUCA ? differences of membrane lipid between bacteria and archaeal Bacteria versus Archaeal 所有原核細胞都配備堅固的細胞壁 Classification of bacteria by dye staining What message we learn from such difference? LUCA apparently did not have a membrane comparable to that in either modern archaea or bacteria. The bubbly mineral cells have their own inorganic walls, which were lined in some regions by hydrothermally synthesized lipids – that were eventually replaced by enzymatically derived lipid membranes, independently, in the archaeal and eubacterial stem lineages. 細胞的演化 • 18-20 億年前 – 一個全新的生命型態 – 真核細胞 eukaryotes – 如何從環境中取得食物? LUCA Is Eucarya independently evolved from Archaea and Bacteria? 真核細胞如何從簡單的原核生物演化出來？ 1, 柔軟的細胞膜 (細胞壁的消失)加上複雜的細胞骨架； 2, 複雜的胞器結構 (細胞核、粒腺體等) 單細胞間的軍備競賽 •抗生素 –生物所合成（並分泌），殺死或抑制起它生物的 物質；大都是二級代謝物（一級代謝的衍生物） –已知約六千種 •約三分之二為鏈黴菌所產生 •生產菌也會對自己的產生的抗生素敏感 –抗藥性基因與合成基因在一起，一起表現 –抗藥性基因擴散到它類細菌（特別是後抗生素期 的病源菌） Targets of Antibiotics Strategy to Escape • Antibiotics resistant gene – Digesting enzyme – Increase exporter protein • To change the structure of targets (archaeal) – Ribosome (rRNA and ribosomal proteins) – RNA polymerase • To take alternative way to increase strength of the cell membrane – Lost cell wall – Invention of cytoskeleton 真核細胞 (eukaryotes): Lost cell wall and Cytoskeleton under the plasma membrane Origin of nucleus F: food vacuole L: lysosome 柔軟的外套:吞噬作用（phagocytosis） 真核細胞的起源 An archaeal origin of eukaryotes supports only two primary domains of life Nature 504: 2 3 1-6; 2013 An archaeal origin of eukaryotes supports only two primary domains of life Nature 504: 2 3 1-6; 2013 Origin of mitochondria: 整廠輸出的「基因改造」; 吃掉它, 不如共生互利! But when this event occur? Reconciling an archaeal origin of eukaryotes with engulfment: a biologically plausible update of the Eocyte hypothesis. Research in Microbiology 162 (2011) 71-76 Many unicellular eukaryotes that lack mitochondria yet contains an alternative organelle, the hydrogenosome, involved in pyruvate metabolism. Hydrogenosomes, mitochondria and early eukaryotic evolution. IUBMB Life. 2003 Jul;55(7):387-95. 曾有真核細 胞是不含粒 腺體的！ 所有真核細 胞都曾含有 過粒腺體。 Reconciling an archaeal origin of eukaryotes with engulfment: a biologically plausible update of the Eocyte hypothesis. Research in Microbiology 162 (2011) 71-76 Martin W and Müller M "The hydrogen hypothesis for the first eukaryote". Nature 392: 37–41; 1998. Proteins Encoded by Eukaryotic Genes of Archaebacterial and Eubacterial Ancestry Are Enriched in Different Cell Compartments, yet Intertwined. PNAS 110: E1594–E1603; 2013 協力廠群的「基因改造」 多細胞生物的誕生---結合與分工 多細胞生物的特質 • 細胞間的結合 (Association) – 黏合蛋白還是堅固的細胞壁 • 細胞間的分工：分化 (Differentiation) – 溝通與協同 – 消化與輸送 – 移動與支撐 – 防禦與保護 • 生殖 (Reproduction) • 體型的發育(Pattern development) Major transitions to multicellularity: the formation of a cooperative group; the transformation of that group into an integrated entity. Cooperation, division of labor, communication, mutual dependence, and negligible within-group conflict. PNAS 112 : 10113-119; 2015 A ratchet moving in its "forward" direction. 在這裡還有那一類的多細胞生物沒有被提到？ The private life of plants-The seeds of a dandelion begin their flight(p17) The private life of plants-South African ants hauling the seed of a plant down into the underground nest, in order to eats its coating(p24) The private life of plants-The fearsome seed-pod of the African grapple plant (p23) Storage root Transverse section of root 2-mg phloem fragments Fragments cultured in nutritive medium Free cells in suspension A View of Life-fig 8-3 (p199) “Embryoid” from cultured free cells Plantlet Flowering plant From left, a choanoflagellate colony, feeding cells of sponges that resemble choanoflagellates and a choanoflagellate with its long flagellum and collar of filaments. •One hypothesis for origin of animals from a flagellated protist suggests that a colony of identical cells evolved into a hollow sphere. •The cells of this sphere then specialized, creating two or more layers of cells. 地球上生命的誕生與演化： 一個偶發的事件？還是一個必然的結局？ • Monod: Chance and Necessity 1971 • Boeing 747 • 每秒擲一次骰子，連續擲出140次6需要多 久時間？ • 6的140次方秒，比宇宙的歷史還要久！ 在不可能的物理世界中，複雜的 生命如何可能誕生？ • 問題出在什麼才叫連續？ • 如果中間不能出錯，一次不對，前面的努 力全功竟棄！那剛才的答案就是對的！ •但是如果每擲出一亇6就把它記在紙上，完 成連續140次6的紙上記錄，只要花840秒! 自由碰撞的石塊，需要多久時間才能形成 這樣奇特的結構？ Forever! Solution 時間加上歷史刻痕的累積，任何特異結構 的形成都是可能的。 那些特異結構会存留下，來就得看環境的 淘汰或選擇了！ 預先存在一亇設計家的假設是不必要的！ 生物學：一亇帶着歷史經驗的科學 “Any living cell carries with it the experiences of a billion years of experimentation by its ancestors” “ A physicist looks at biology” Max Delbruck, 1949 "Nothing in biology makes sense except in the light of evolution." T. Dobzhansky 1900 - 1975. • Project 523 (May 23, 1967)—set out to battle chloroquine-resistant malaria • In early 1969, Tu was appointed head of the Project 523 research group at China Academy of Chinese Medical Sciences, Beijing • By 1971, her team had made 380 extracts from 200 herbs. The researchers then assessed whether these substances could clear Plasmodia from the bloodstream of mice infected with the parasite. • One of the extracts looked particularly promising: Material from Qinghao • October 1981, Professor Tu, invited to present her work at a meeting sponsored by the World Health Organization • “食譜52與病症”，漢代馬王堆墓葬中出土(168 BC)。 • 東晉葛洪《肘後備急方》，書中抗瘧紀錄「青蒿一握，水 兩升漬，絞取汁，盡服之」 Received 11/15/1978 Published March 1979 Received 12/7/1978 Published April 1979 王正中教授 (王正方的哥哥)