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1、,比较基因组学与分子进化 Comparative genomics and molecular evolution,11/3/2019,比较基因组学与分子进化在生命科学研究中应用及贡献,1.模式生物测序的意义 模式生物 DNA测序技术 2.新学科的快速诞生 3.推动物种起源和生物进化发展 4.研究思路和方法突破 Genetics VS Reverse genetics,Breakthrough and milestone for genomic era,New fields of biology open up Genetics VS Reverse genetics,Case analysi
2、s in model organism,Key Point of Understanding Development,What Genes involved in a given development process How those genes (and proteins) work at cellular/molecular level How those genes (and proteins) activities are regulated,How to identify Genes critical in a given development process,1. Genet
3、ics: What wrong with a mutant lacking a functional gene tells the normal role of the gene. Start with mutants, then the gene & how it works 2. Reverse genetics: Starting with a gene of known identity, modifying its expression or activity to reveal its development function,Four model organisms,Arabid
4、opsis,Mouse,Drosophila,C.elegans,Drosophila mutant affects WING development,Normal (wild type, WT),Mutant,Arabidopsis seedling development,Why Reverse genetics (From gene to phenotype/function),1. Many undefined genes are sequenced due to the advancement of sequence technology 2. Can control where,
5、when, and how much an active gene product to be made 3. Easy to design specific mutations into the gene product 4. Add TAGs to a gene product to simplify its study within the cell 5. Create mutation on gene that has no available mutation or not feasible to have,Why Reverse genetics: From gene to phe
6、notype/function,1. Many unknown genes are sequenced due to the advancement of sequence technology,2. Can control where, when, and how much an active gene product to be made,3. Easy to design specific mutations into the gene product,4. Add TAGs to a gene product to simplify its study within the cell,
7、5. Create mutation on gene that has no available mutation,3 common ways to control where, when, andhow much an active gene product in a cell,2. Gene Silencing or Antisense approach to control the level of mRNA of a given gene 3. Expression of desirable Dominant Affecting Mutant form,1. Utilization o
8、f desirable regulatory sequence to drive the expression of your gene product,基因结构,(,DNA),外,显子,内含子,启动子,25,-,30,bp,A,-,T,C,-,G,tttcag,ATC,GTTAGgt,正确剪接位点,5,3,2-5kb,attcagGAT ATTTCAgt,外显子,成熟,(,mRNA,),结构,蛋白质,(20,氨基酸,),64,密码子,起始密码：,ATG,N,终止密码：,TAA TAG TGA,5,3,C,Promoter:GFP reporters reveal worm Cadherin
9、gene expression,The chimeric soybean ferrition gene construct. Soybean ferritin cDNA was fused to rice endosperm-specific Glb-1 promoter. The chimeric genes were inserted into the pGPTV-35S-htp binary Vector between the restriction sites SalI and SacI,In situ western hybridization of ferritin transg
10、enic rice seeds. NT: Non-transformants FK22: transformants with soybean ferritin gene soyferH-1directed by GluB-1 DF: double transformants with soybean ferritin gene soyferH-1directed by GluB-1 and Glb-1 promoter. OF: transformants with soybean ferritin gene soyferH-1directed by Glub-1,em embryo, en
11、 endosperm, sa subaleurone,Qu et al., 2019, Planta,GluB-1: glutelin gene promoter Glb-1: globulin gene promoter,Ye X. et al., 2000, Science,Golden rice - Three -carotenoid (provitamin A) biosynthetic enzymes (two from plants and one from bacteria) were engineered for simultaneous expression in rice
12、endosperm. The resulting first generation transgenic rice produced yellow endosperm containing -carotene at levels that would provide 10% of the recommended daily allowance with an average daily rice intake.,Transgenic multivitamin corn through biofortification of endosperm with three vitamins repre
13、senting three distinct metabolic pathways,(Naqvi et al., 12/5/2009, PNAS),The transgenic kernels contained169-fold the normal amount of -carotene, 6-fold the normal amount of ascorbate, and double the normal amount of folate.,How to Silencing a Gene,mRNA,Form double stranded hairpin RNA (dsRNA),The
14、dsRNA results in formation of random 20-22 nts small RNA, which then triggers the degradation of the mRNA where the homologous derived from.,The mechanisms of RNAi, RNA interference, RNAi,1.起始步 沉默触发物被裂解，产生小干扰性RNA （small interfering RNAs，siRNAs） 2.第二步：效应步 siRNAs与多种亚单位形成复合物RNA诱导的沉默复合物（RISC），然后以RISC的方式
15、降解单链的靶mRNA. 3.第三步：沉默效应的放大和扩散 整个生物体。,Fire et al., 2019, Nature,Genetic interference following ingestion of dsRNA-expressing bacteria by C.elegans a.General scheme for dsRNA production, bacterial strain(BL21/DE3). b. C.elegans show high GFP-fluorescence in body muscles c. 12% animals show a dramatic d
16、ecrease in GFP,The Nobel Prize in Physiology or Medicine 2019,for their discovery of RNA interference - gene silencing by double-stranded RNA,Case 1: Innate versus learned odour processing in the mouse olfactory bulb,Kobayakawa et al., 2019.Nature.450: 1-8,Mouse kiss Cat,RNAI silencing 16D10 parasitism gene in preparasitic M. incognita J2,Huang et al., PNAS, 2019,Reduction transcript: 93-97%,Reduction protein: 65-69%,Suppression
