【正文】
低等真核生物 1020% 高等植物 80% repetitive sequence 高等動物 50% 多為結(jié)構(gòu)基因 . 重復(fù)序列形成的理論 a) 滾環(huán)擴增 — 突變 ( AmplificationMutation ) Mutation insertion cycling amplification 5‘ 3‘ 3‘ 3‘ DNA → RNA → DNA mRNA/cDNA DS cDNA b) 反轉(zhuǎn)座插入 ( retrotransposition ) c) 跳躍復(fù)制 saltatory replication C A A C Mutation in 4 site Insert C Insert triple mutation Saltatory replication 9 bp repeat 27 bp repeat 58 bp repeat 58 bp repeat 116 bp repeat 基因的重復(fù)可以通過復(fù)制產(chǎn)生 ( duplication) 復(fù)制后的拷貝發(fā)生突變和突變累積 (divergence) 形成基因簇 gene cluster 分化成執(zhí)行不同功能的基因 Gene duplication is a major force in evolution 抗病基因簇的形成 d) 不對稱交換 (unequal crossingover) unequal crossingover 5 Units 5 Units 6 Units 4 Units 基因組比較研究 禾本科植物 基因組比較 ● 基因組比較研究表明; 5 Rice genome Maize genome 40 Rice genome Wheat genome 但基因組成,排列表現(xiàn)驚人的相似 差異多存在于 repetitive sequence ﹤ ﹤ . 間隔基因( splitting gene) Phillip Sharp amp。Roberts Ad2 (1977) ( mini revolution) Richard J. Roberts Phillip A. Sharp Nobel Prize 1993 Pierre Chambon (France) (1977) ovalbumin of chicken Eukaryotic cellular gene is also split . 間隔基因的發(fā)現(xiàn) Phillip A. Sharp Nobel Prize 1993 ( 49y) 布什給 Philip Sharp 頒發(fā)國家科技獎?wù)? 曾獲得 40項獎勵,擁有 4個院士稱號(美國科學院、美國文理科學院、 美國醫(yī)學研究院、美國哲學研究院) K eop = 1 eop = 104 of λk efficiency of plating (eop) = 103 of λc C λphage eop = 1 ● 限制性核酸內(nèi)切酶的發(fā)現(xiàn) 1965 Arber. W a) restriction alien DNA with restriction endonuclease (RE) b) Modification enzyme in host c) Alien DNA fate of be restricted or be modified d) There are different RE in different host of bacterial Werner Arber Nobel Prize 1978 l Restriction Endonuclease 的種類 ● Splitting gene 的證實 1977 Pierre Chambon Ovalbumin cDNA as probe EcoRI HindIII Oviduct DNA Erythrocyte DNA cDNA 中沒有 HindIII, EcoRI 切點??? Splitting seq. in the 5’ end of Hexon cp gene of Ad2 DNA of Ad2 + EcoRI amp。 HindIII mRNA of Hexon cp Sharp group Roberts group 1977 And presentation in CSH PNAS 74: 3173, 1977 Total DNA of chicken cDNA 7 DNA loop Chambon was inspired by Berget’s report Berget, S. M., C. Moore, and P. Sharp. 1977. PNAS 74。 31713175 Ovalbumin cDNA RE map Hinf I Hinf II Hea III Hinf III Pst I Hinf IV ( No EcoRI Hind III RE site ) the cDNA probe be digested by Hinf III and PstI Labeling with p32 Probe A Probe C Probe B Probe cDNA A B C Oviduct total DNA Digested with EcoR I and Hind III presume Hinf I Hinf II Hea III Hinf III Pst I Hinf IV EcoRI, HindIII EcoRI, HindIII Spacer Spacer cDNA mRNA presume Hinf I Hinf II HeaIII Hinf III Pst I Hinf IV DNA 轉(zhuǎn)錄 逆轉(zhuǎn)錄 雖 機會錯過 但 推論正確