1、基因组进化中的遗传学问题.PPT

突变的基本类型 Single nucleotide polymorphism (SNP) Insertion/deletion (s) (Indel) Structural variation, Copy number variation Q:丰富的遗传变异从何而来？ (变异的来源并非十分清楚) Result and discussion 结果3：Indel大小影响SNP累积 结果： 1. 与Indel越近，SNP越高;2. Indel越密集，SNP越高;3. Indel越大，SNP越高. What did we observe? The distance to indel, indel density indel size affect nucleotide divergence (D) Indel was the center of the distribution of mutation-rate Each indel independently affected the surrounding areas. Cause of the mutation-rate change? potential factors Selection Regional-difference of DNA 突变热点区域内SNP与Indel各自发生，即Indel并不影响其周围SNP的积累 Our hypotheses Indel induced mutation indel的存在会通过某种机制影响周围SNP的积累 1. selection?(1) Coding(a) and non-coding(b) regions Coding(a) and non-coding(b) regions (2) Intron regions of chr1(Human vs. Chimp) 2. Regional-difference of DNA 1) Is Indel a MARKER of mutation hotspots? 2) The effect of paralogous sequences and transposons 3) The effect of recombination 1) Is indel a MARKER of a mutable segment or a CAUSE of mutation? Indel is a MARKER of mutation hotspots Regional-difference Indel is a CAUSE of mutation Indel induced mutation There is a simple 3-species test which can discriminate between MARKER vs. CAUSE Polarize indels The gaps in two-sequence alignments Polarize indels The gaps in two-sequence alignments Polarize base substitutions The substitutions in two-sequence alignments Polarize base substitutions The substitutions in two-sequence alignments 3-species test Results of 3-species test Paralogous sequences and transposons Estimating the relative increase计算突变效应: indel对周围序列有5倍的诱变作用 The effect of recombination Possible molecular mechanism The intrinsic factor of genomic mutation 外因：radiation, chemical, UV 内因：indel Conclusion 以indel为中心的突变率的分布 在杂合体中indel对于其周围序列有诱变作用，突变率大约会升高5倍 Indel诱变是一种普遍的突变机制，并且在创造遗传差异中起着重要作用 实例研究1 总结：Indel存在特殊遗传行为——非对称特性： 突变效应、重组效应、隔离效应 结束语 1. 生物信息从有序向无序变化的能力超乎想象 （Indel诱发更多的变异） 2. 生物信息从无序向有序变化的能力也超乎想象 （密码子有序排列提高蛋白合成效率） 研究人员 D.Tian