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1、Xunchao Xiang Southwest University of Science and Technology,Chapter 7 Chromosome Mutations: Variation in Number and Arrangement,7.1 Variation in Chromosome Number: An Overview 7.2 Nonjunction: The Origin of Aneuploidy 7.3 Monosomy 7.4 Trisomy 7.5 Polyploidy and Its Origins 7.6 Variation in Chromoso
2、me Structure and Arrangement: An Overview 7.7 Deletions 7.8 Duplications 7.9 Inversions 7.10 Translocations,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Genome: the total set of genes contained in a haploid of the species constitutes th
3、e genome. The all chromosomal number of a gamete produced from diploid is designated as basic chromosome number 染色体基数, and make up a single complete set (x) . Monoploid (x)一倍体: individual, which has only one set of chromosomes. Haploid(单倍体): individual only with gametic chromosomes. Its all chromoso
4、mal number is indicated as n.,Xunchao Xiang Southwest University of Science and Technology,1. 单倍体的产生,(1)自然产生：由单性生殖产生 未受精的雌、雄配子，甚至助细胞、反细胞等直接发育形成单倍体胚。 部分动物，如膜翅目昆虫(蜂、蚊)和某些同翅目昆虫(白蚁)的雄性个体都是孤雌生殖形成的自然单倍体。 (2) 人工获得单倍体 花药培养：花药离体培养诱导配子体(花粉或子房)发育形成单倍体植株 这是应用最为广泛、成功的人工方法 种间或属间远缘杂交 栽培大麦(Hordeum vudare, 2n=2x=14)
5、与野生球茎大麦(H. bulbosus, 2n=2x=14)杂种胚发育过程中，两物种染色体的行为不协调可导致球茎大麦的染色体逐渐丢失(称为染色体消减现象)，可获得大麦的单倍体植株,Xunchao Xiang Southwest University of Science and Technology,花药培养获得单倍体,染色体消减获得单倍体大麦,Xunchao Xiang Southwest University of Science and Technology,2. 单倍体在遗传育种研究的应用,(1)提高育种的选择效率、加速育种进程 基因成单，加倍，纯合体 (2)作为良好的遗传研究材料 基
6、因成单，每个基因都发挥作用 (3)用以分析染色体组间同源关系 部分同源关系,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Euploid(整倍体): an individual that has complete sets of chromosomes present. Aneuploid (非整倍体): an individual gains or loses one or more chromosomes, but no
7、t a complete set. Polyploid (多倍体): an individual with more than two complete sets chromosomes present.,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Terminology for Variation in Chromosome Numbers Term Explanation Disomic (normal) 2n Ane
8、uploid 2nx chromosomes Monosomic 2n1 Double Monosomic 2n11 Nullisomic 2n2 Trisomic 2n1 Double Trisomic 2n11 Tetrasomic, pentasomic, etc. 2n 2, 2n 3, etc. Euploid Multiples of n Diploid 2n Polyploid 3n,4n,5n,Xunchao Xiang Southwest University of Science and Technology,Polyploidy,Term Explanation Trip
9、loid(三倍体) 3n Tetraploid (四倍体) 4n Pentaploid (五倍体) 5n Autoploid (同源多倍体) Multiples of the same genome Allopolyploid (异源多倍体) (Amphidiploid),Multiples of different genomes,Xunchao Xiang Southwest University of Science and Technology,Characteristics of polyploid,(1). Polyploid often increases plant size
10、(included cell, organelle etc.).,Xunchao Xiang Southwest University of Science and Technology,Characteristics of polyploid,(2) Polyploid often increases plant vigor (heterosis). (3). Fertility of gametes are often reduced, even infertile completely.,Xunchao Xiang Southwest University of Science and
11、Technology,Hypoploid and Hyperploid,Hypoploid (亚倍体)： the individual that its chromosome number is loss than diploid. For example, monosomic, double monosomic, nullisomic, etc. Hyperploid (超倍体)： the individual that its chromosome number is more than diploid. For example, trisomic, tetrasomic, etc.,Xu
12、nchao Xiang Southwest University of Science and Technology,7.2 Nonjunction: The Origin of Aneuploidy,Xunchao Xiang Southwest University of Science and Technology,7.3 Monosomy(单体性),Monosomy: The loss of one chromosome in a normal diploid produces a (2n 1) complement and is called monosomy or monosomi
13、c. For example, T urner syndrome(45, XO).,Xunchao Xiang Southwest University of Science and Technology,7.3 Monosomy,Cri-du-Chat Syndrome(猫叫综合症) This syndrome is associated with the loss of part of the short arm of chromosome 5, strictly, this case should be referred to as segmental deletion. Its gen
14、etic constitution may be designated as 46, 5p, meaning that such an individual has all 46 chromosomes but that some of the p arm of one member of the chromosome 5 pair is missing. Incidence: 1/50,000 live births.,Xunchao Xiang Southwest University of Science and Technology,Cri-du-Chat Syndrome,Xunch
15、ao Xiang Southwest University of Science and Technology,7.4 Trisomy(三体性),The addition of an extra chromosome products somewhat more viable individuals in both animal and plant species than does the loss of a chromosome. Down Syndrome It is the only human autosomal trisomy in which a significant numb
16、er of individuals survive longer than a year past birth. It results from trisomy of chromosome 21, and is also called simply trisomy 21(is designated 47, 21) Incidence: 1/800 live birth.,Xunchao Xiang Southwest University of Science and Technology,Down Syndrome,Xunchao Xiang Southwest University of
17、Science and Technology,Down Syndrome,Xunchao Xiang Southwest University of Science and Technology,Viability in Human Aneuploid Conditions,Patau Syndrome ( 47,13 ),Edwards syndrome (47, 18 ) They result in severe malformations and early lethality.,Xunchao Xiang Southwest University of Science and Tec
18、hnology,Viability in Human Aneuploid Conditions,At least 1520 percent of all conceptions terminate in spontaneous abortion. About 30 percent of all spontaneously aborted fetuses demonstrate some form of chromosomal anomaly, and approximately 90 percent of all chromosomal anomalies are terminated pri
19、or to birth as a result of spontaneous abortion. A large percentage of those demonstrating chromosomal abnormalities are aneuploids. The aneuploid with highest incidence among abortuses is the 45,X condition.,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins
20、,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins,1. Origin of polyploidy Polyploid originates in two ways: (1) Autopolyploid: the addition of one or more extra sets of chromosomes, identical to the normal haploid complement of the same species. (2) Allopol
21、yploidy(异源多倍体): the addition of one or more extra sets of chromosomes, different to the normal haploid complement of the same species.,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins,Amphidiploid,Xunchao Xiang Southwest University of Science and Technology
22、,Autopolyploid(同源多倍体),Having being replicated, do not appear,Xunchao Xiang Southwest University of Science and Technology,Allopolyploidy(异源多倍体),Xunchao Xiang Southwest University of Science and Technology,2. 多倍体的形成途径及其应用,(1)未减数配子结合减数分裂 (2)体细胞染色体数加倍有丝分裂 (3)人工诱导多倍体的应用,Xunchao Xiang Southwest Universit
23、y of Science and Technology,(1)未减数配子结合,桃树(2n=2x=16=8)的未减数配子(n=2x=16)融合形成同源多倍体 未减数配子未减数配子 四倍体(2n=4x=32=8) 未减数配子正常配子 三倍体(2n=3x=24=8),Xunchao Xiang Southwest University of Science and Technology,(1)未减数配子结合,种间杂种F1未减数配子融合形成异源多倍体 例：,Xunchao Xiang Southwest University of Science and Technology,(2)体细胞染色体数加倍
24、,体细胞染色体加倍的方法 最常用的方法：秋水仙素处理分生组织 阻碍有丝分裂细胞纺锤丝(体)的形成 处理浓度：0.01-0.4%(0.2%) 处理时间：视材料而定 间歇处理效果更好 同源多倍体的诱导 诱导二倍体物种染色体加倍同源多倍体(偶倍数) 异源多倍体的诱导 诱导杂种F1染色体加倍双二倍体 诱导二倍体物种染色体加倍同源多倍体杂交双二倍体,Xunchao Xiang Southwest University of Science and Technology,(3)人工诱导多倍体的应用,1.克服远缘杂交的不孕性 2.克服远缘杂种的不实性 3.创造种间杂交育种的中间亲本 实质是克服远缘杂交不育性
25、 4. 人工合成新物种、育成作物新类型 人工合成同源多倍体 方法：直接加倍 例：同源四倍体芥麦、同源三倍体甜菜 人工合成异源多倍体 方法：物种间杂交杂种F1染色体数目加倍 实例：八倍体小黑麦(图示) 、六倍体小黑麦(图示),Xunchao Xiang Southwest University of Science and Technology,八倍体小黑麦的人工合成与应用,Xunchao Xiang Southwest University of Science and Technology,六倍体小黑麦的人工合成与应用,Xunchao Xiang Southwest University o
26、f Science and Technology,7.6 Variation in Chromosome Structure and Arrangement: An Overview,The second general class of chromosome aberrations includes structural changes that delete, add, or rearrange substantial portions of one or more chromosomes. Included in this category are deletions and dupli
27、cations of genes or part of a chromosome and rearrangements of genetic material in which a chromosome segment of a nonhomlogous chromosome, or merely transferred to another chromosome.,Xunchao Xiang Southwest University of Science and Technology,染色体结构变异,结构变异的形成：断裂重接 使染色体产生折断的因素： 自然：温度剧变、营养生理条件异常、遗传因
28、素等； 人为：物理射线与化学药剂处理等。 染色体折断的结果： 正确重接：重新愈合，恢复原状； 错误重接：产生结构变异； 保持断头：产生结构变异。 结构变异的基本类型：缺失、重复、倒位、易位。 形成、类型与特点； 细胞学特征与鉴定； 遗传效应。,Xunchao Xiang Southwest University of Science and Technology,7.7 Deletions(缺失),Deletion: when a chromosome breaks in one or more places and a portion of it is lost, the missing p
29、iece is called a deletion (or a deficiency),Deletion,Terminal deletion (顶端缺失),Intercalary deletion (中间缺失),Xunchao Xiang Southwest University of Science and Technology,7.7 Deletions,Xunchao Xiang Southwest University of Science and Technology,7.7 Deletions,Terminal deletion,Intercalary deletion,Xunch
30、ao Xiang Southwest University of Science and Technology,断裂融合桥,顶端缺失的形成(断裂) 复制,姊妹染色单体顶端断头连接(融合),有丝分裂后期 (桥) 新的断裂,Xunchao Xiang Southwest University of Science and Technology,缺失的细胞学鉴定,无着丝粒断片： 最初发生缺失的细胞在分裂时可见无着丝粒断片。 缺失环(环形或瘤形突出)： 中间缺失杂合体偶线期和粗线期出现； 二价体末端突出： 顶端缺失杂合体粗线期、双线期，交叉未完全端化的二价体末端不等长。,缺失染色体的联会,Xuncha
31、o Xiang Southwest University of Science and Technology,缺失的遗传效应,缺失区段上基因丢失导致： 基因所决定、控制的生物功能丧失或异常； 基因间相互作用关系破坏； 基因排列位置关系改变。 影响缺失对生物个体危害程度的因素： 缺失区段的大小； 缺失区段所含基因的多少； 缺失基因的重要程度； 染色体倍性水平。,缺失纯合体： 致死或半致死。 缺失杂合体： 缺失区段较长时，生活力差、配子(尤其是花粉)败育或竞争不过正常配子； 缺失区段较小时，可能会造成假显性现象或其它异常现象(猫叫综合症)。,Xunchao Xiang Southwest Univ
32、ersity of Science and Technology,猫叫综合症,第5号染色体缺失（短臂缺失）患儿发 出咪咪声，耳位低下，智商仅2040.,Xunchao Xiang Southwest University of Science and Technology,Robert Horry，七枚NBA季后赛总冠军戒指，并且是NBA历史上投中三分球总数第一。“关键先生”的名号享誉联盟。,2011年6月13日，他17岁的女儿阿什利-霍里，因为一种罕见的基因疾病于美国当地时间周二去世。这疾病被称做“1p36缺失综合征”，一种神经性并发症大脑神经瘫痪，有着非常严重的呼吸衰竭疾病，并有多种并发症
33、。 News title: Daughter Of Robert Horry Passes Away At 17. Her disorder became known as the 1p36 deletion syndrome. It is caused when a child is born missing a part of chromosome No. 1,1p36 deletion syndrome,Xunchao Xiang Southwest University of Science and Technology,缺失杂合体的假显性现象,Xunchao Xiang Southw
34、est University of Science and Technology,7.8 Duplications(重复),Duplication: when any part of the genetic material a single locus or a large piece of a chromosome is present more than once in the genome, it is called a duplication.,Xunchao Xiang Southwest University of Science and Technology,7.8 Dupli
35、cations,Duplication,Tandem duplication (顺接重复),Reverse duplication (反接重复),Xunchao Xiang Southwest University of Science and Technology,7.8 Duplications,Gene Redundancy (基因冗余)and Amplification Ribosomal RNA Genes Gene Redundancy: A product is coded by multiple copies of genes. Gene Amplification: the
36、process by which gene sequences are selected and differentially replicated either extrachromosomally or intrachromosomally.,Xunchao Xiang Southwest University of Science and Technology,7.8 Duplications,The Bar Mutation in Drosophila,Bar eye,Oval eye,Xunchao Xiang Southwest University of Science and
37、Technology,重复的细胞学鉴定,重复圈(环),果蝇X染色体上16A区段重复的形成,Xunchao Xiang Southwest University of Science and Technology,The genetic effects of duplication,(1). Dosage effect 果蝇眼色遗传的剂量效应，红色(V+)对朱红(V)为显性； 杂合体(V+V)表现为红色； 但(V+VV)的表现型却为朱红色。 说明2个隐性基因的作用已经超过自己的显性等位基因，改变了原来的一个隐性基因与一个显性基因的平衡关系。 (2). Position effect,Xuncha
38、o Xiang Southwest University of Science and Technology,7.9 Inversions(倒位),Inversion: is a type of chromosomal aberration in which a segment of a chromosome is turned around 180within a chromosome.,Inversion,Paracentric inversion (臂内倒位),Pericentric inversion (臂间倒位),Xunchao Xiang Southwest University
39、of Science and Technology,Pericentric inversion,Xunchao Xiang Southwest University of Science and Technology,Consequences of Inversions During Gamete Formation,Inversion heterozygotes: organisms with one inverted chromosome and one noinverted homolog. When pairing between inversion heterozygotes in
40、meiosis is accomplished only if they form an inversion loop. If crossing over occurs within the inversion loop:,Xunchao Xiang Southwest University of Science and Technology,Paracentric inversion heterozygote,Normal,Inverted,Xunchao Xiang Southwest University of Science and Technology,Paracentric inv
41、ersion heterozygote,Normal,Inverted,Xunchao Xiang Southwest University of Science and Technology,Paracentric inversion heterozygote,Anaphase bridges,Xunchao Xiang Southwest University of Science and Technology,Pericentric Inversion Heterozygote,Normal,Inverted,Xunchao Xiang Southwest University of S
42、cience and Technology,Pericentric Inversion Heterozygote,Xunchao Xiang Southwest University of Science and Technology,Genetic Effects of Inversion,(1). Partial sterility of inversion heterozygote. Reasons: producing of deletion or duplication gametes. (2). Original arrangement sequence of genes in c
43、hromosome is changed. Distance between genes is changed; Position effect probably takes place; Values of crossing over between genes in inversion heterozygote reduced. (3). Inversion is one of important factors in evolution of organism.,Xunchao Xiang Southwest University of Science and Technology,7.
44、10 Translocations(异位),Translocation: is the movement of a chromosomal segment to a new location of nonhomologous chromosome in the genome.,Translocation,Simple translocation (简单异位),Reciprocal translocation (相互异位),Xunchao Xiang Southwest University of Science and Technology,Simple translocation,Xunch
45、ao Xiang Southwest University of Science and Technology,Reciprocal translocation,Xunchao Xiang Southwest University of Science and Technology,Reciprocal translocation,Xunchao Xiang Southwest University of Science and Technology,Reciprocal translocation,Crosslike configuration(十字结构),Evidence in ident
46、ifying of cytology,Xunchao Xiang Southwest University of Science and Technology,Reciprocal translocation,Alternate(交替式),Adjacent(邻近式),Xunchao Xiang Southwest University of Science and Technology,Synapsis and segregation of translocation heterozygote,Normal,Balanced,D,D,D,D,Alternate,Adjacent,Xunchao
47、 Xiang Southwest University of Science and Technology,Segregation of translocation heterozygote,Alternate segregation: to produce normal and balanced gametes. Adjacent segregation: to produce duplicate and delete gametes.,Xunchao Xiang Southwest University of Science and Technology,Genetic effects o
48、f translocation,(1).Semisterility(半不育性). (2). Linkage group of organism is changed by translocation. (3). Values of crossing over of genes in translocation heterozygote is reduced. (4). Translocation may produce new species and leads to involution.,Xunchao Xiang Southwest University of Science and Technology,Translocation in Humans: Familial Down Syndrome,Robertsonian Translocation,45 chromosomes,知 识 点 染色体数目变异概况；非整倍体产生的起源；单体性；三体性；多倍体及其起源；染色体结构变异概况；缺失；重复；倒位；易位。 重 点 整倍体和非整倍体的类型；多倍体的特征及其起源；结构变异的类型及其遗传效应。 难 点 臂内倒位杂合体和相互易位杂合体可能产生的配子类型和育性分析。,Highlights,基本要求 1. 识 记：染色体基数（basic chr