Chapter 10 Inheritance analysis of chromosome aberration

• Variation in chromosome structure• Deletions• Duplication• Inversions• Translocations• Variation in chromosome number• Euploid• Aneuploid

第十章 染色体畸变的遗传分析

• 染色体结构变异• 缺失• 重复• 倒位• 易位• 染色体数目的变异 • 整倍体• 非整倍体

Characteristics of Drosophila salivary gland chromosomes果蝇唾腺染色体特性

• Magnitude and extensibility

• Somatic synapsis• Band and interband• Puff Structure • 巨大性和伸展性• 体联会• 横纹结构 Puff 结构

Variation in chromosome structure—deletions染色体结构变异 -- 缺失

DeficienciesThe loss of a segment from a

normal chromosomeThe types of deficiencies Intercalary (deletion) and

terminal

染色体丢失了一个片段叫缺失缺失类型 :

中间缺失 末端缺失

Formation of Terminal deletion末端缺失的形成

Formation of intercalary deletion中间缺失的形成

Cytological behavior细胞学效应

A loop is generally observed if the deficiency is long enough and is located an interstitial region

普遍生成一个缺失环

Chromosomal synapsis of deficiency缺失染色体联会

Deletion loop of Drosophila salivary gland chromosome果蝇唾腺染色体的缺失环

Genetic effect of deletion heterozygote缺失杂合子的遗传学效应

Pseudodominant Lethal effectFormation of ring

chromosome and breakage-fusion-bridge cycle

假显性致死效应 形成环状染色体和断裂

融合桥循环

Pseudodominant effect of deletion heterozygote缺失杂合子的假显性效应

Example of deletion in human--Cri-du-Chat Syndrome

人类缺失实例 -- 猫叫综合症

The karyotype of Cri-du-Chat Syndrome猫叫综合症的核型

Variation in chromosome structure--duplicationsAn extra piece of chromosome segment either attached to the same homologous chromosome or transposed to one of the non-homologous members of the genome

重复：一个染色体上的某一片段出现两份或两份以上的现象

Types of duplications重复的种类

Tandem duplication-- 串联重复 Reverse tandem duplication-- 反向串联重复

Formation of duplication 重复的形成

Non-equal cross-over of homogenous chromosome同源染色体的不等交换

Cytological behavior of duplication heterozygote重复杂合体的细胞学行为

Duplication loop重复环

Genetic effect of duplication heterozygote重复杂合子的遗传效应

Dosage effect

Position effect

Lethal effect

剂量效应

位置效应 致死效应

The Bar mutation in Drosophila果蝇的棒眼突变

The duplication at 16A of X chromosome in Drosophila 果蝇 X 染色体在 16A 的重复

Position effect位置效应

Variation in chromosome structure-- inversions

A change in linear sequence of the genes in a chromosome which results in the reverse order of genes in a chromosome segment

倒位：染色体上某一片段发生颠倒，造成染色体上基因顺序重排的现象

Types of inversions-- 倒位的种类Based on the position of two breaks of an inversion in relation to the kinetochore of a chromosome, inversion are of two types: Paracentric inversion ： both breaks occur in the same arm so the inverted region does not include a kinetochore.Pericentric inversion ： the two breaks occur in opposite arms of a chromosome. Dicentric bridges and acentric fragments at anaphase-I and –II are not observed in pericentric inversion臂内倒位：倒位出现在同一臂内，因此倒位不包括着丝粒臂间倒位：倒位发生在一条染色体的两条臂上

Formation of inversion-- 倒位的形成

Cytological behavior--pericentric inversion细胞学行为 -- 臂间倒位

A loop is usually observed in a heterozygous inversion at pachynema 在粗线期，倒位杂合子会出现一个倒位环

Cytological behavior--paracentric inversion细胞学行为 -- 臂内倒位

At pachynema, a loop is usually observed in a heterozygous inversion

At anaphase-I or –II, chromatin bridge and acentric fragment may be found

在粗线期，倒位杂合子会出现一个倒位环在后期 I 或Ⅱ，可能出现染色体桥梁和无着丝粒片段

Association of inversion heterozygote倒位杂合子的联会

Cross-over of pericentric inversion heterozygotes臂间倒位杂合子的交换

Cross-over of paracentric inversion heterozygotes臂内倒位杂合子的交换

Genetic effect and application遗传效应及应用

1. Changing the linear order of genes in chromosome2. Influencing the organism evolution3. The karyotype is varied in pericentric inversion4. Breakage point can be used a dominant suppressed factor to locate genes in chromosome: crossover repressor to construct balanced lethal system—permanent hybrid

改变基因在染色体上线性排列 影响生物进化臂间倒位可改变细胞染色体核型断裂点可用作显性抑制因子对染色体上的基因定位

Genetic effect and application

Variation in chromosome structure-- translocations

The movement of a chromosomal segment to a new location in the genome易位是一个染色体片段转移到基因组中新的位置

Types of translocation易位类型

Reciprocal translocation: Involveing the exchange of segments between two non-homologous chromosomesWhole-arm translocationRobertsonian translocation相互易位：是发生在两个非同源染色体之间的交换。 整臂易位罗伯逊式易位

Origin of translocation易位的来源

Cytological behavior细胞学行为

At pachynema in meiosis, translocation heterozygote chromosomes form a cross-shaped configuration

在减数分裂粗线期，染色体易位杂合子形成十字型配置

Synapsis and separation of translocation heterozygotes

易位杂合体的联会与分离

Separation of translocation heterozygotes易位杂合体的分离

Genetic effect and application遗传效应及应用

Semi-sterility in diploid species

Constructing new karyotypes or linkage groups, resulting in evolution of

organism. For example: the evolution of rye

Using translocation-gene-linkage technique to gene location

Preventing injurious insects

Using B-A translocations to study gene effects or gene location or relationship among linkage groups

二倍体物种的半不育构建新的染色体核型或连锁群，促时进生物进化。例如：黑麦的演变 使用连锁 - 易位基因技术对基因定位害虫防治 采用易位方法，研究基因效应或定位基因或研究连锁群之间的关系

Application in agricultural production Using translocation technology to construct the autosexing strain in silkworm

Translocation in humans: Familial Down Syndrome人类的易位 -- 唐氏综合症家族

Variation in chromosome number染色体数目的变异

The type of chromosome number variationEuploidAneuploidGenome: The basic set of chromosomes in a gamete of diploid organism is called genome, designed as ‘x’

染色体数目变异的类型 ：整倍体非整倍体基因组： 二倍体生物正常配子中所包含的整套染色体

Euploid-- 整倍体 Euploid: the organisms those contain only complete haploid sets of chromosome Monoploid, x 2n=x

Diploid, 2x 2n=2x n=xTripoid, 3x 2n=3xTetraploid, 4x 2n=4x n=2x

For exampleMaize ： diploid(2n=2x=20, n=x=10)Rice ： diploid(2n=2x=24, n=x=12)Wheat ： sixploid(2n=6x=42, n=3x=21, x=7)

整倍体：以染色体组为单位，呈成套数目的改变，改变后的数目是整倍改变单倍体 , x 2n=x

二倍体 , 2x 2n=2x n=x三倍体 , 3x 2n=3x四倍体 , 4x 2n=4x n=2x

例如：玉米 ： diploid(2n=2x=20, n=x=10)水稻 ： diploid(2n=2x=24, n=x=12)小麦： sixploid(2n=6x=42, n=3x=21, x=7)

Haploid-- 单倍体the organisms contain only a set of chromosomes in a cell, which exhibit the smaller cells, tissues, organs, individuals, and sterility to a degreeThe haploid (n = 2x) of autotetraploid (2n = 4x) shows a higher fertility细胞、组织、器官和生物个体较小，高度不育性

同源四倍体 (2n=4x) 的单倍体 (n=2x) 育性水平高于其它类型

Application in heredity and breeding单倍体在遗传育种研究的应用

To enhance selection efficiency and speed up the process in plant breedingA key material in genetic researchTo analyze the homologous relationship between chromosome groups

提高育种的选择效率、加速育种进程是良好的遗传研究材料用以分析染色体组间同源关系

PolyploidThe organisms contain more than two sets of chromosomesThe organisms contain more than two sets of chromosomesAutopolyploidy: The genomes are alike because one basic genome is multiplied. Most of the autopolyploidy in nature are autotriploids and autotetraploids.Alloployploidy: The organisms which have the combination of chromosome sets from different species occurring as a consequence of hybridization

同源多倍体：染色体是相同的，因为一个基本的染色体是成倍增加。自然界中的大多数是同源多倍体同源三倍体和同源四倍体异源多倍体：是两个或两个以上不同物种杂交，它们的杂种经染色体加倍形成

Origin of autotetraploids— 同源多倍体的来源1. Occasionally appearing spontaneously in natural diploid population by non-disjunction2. Deriving from the progenies of twin seedlings and male sterile 3. Induced from temperature shocks, cell and tissue cultures, irradiations and chemicals (colchicines)

Meiosis and gene segregation of Autopolyploids同源多倍体的减数分裂 和基因分裂特点

Autotriploids-- 同源三倍体Autotriploids (3x, AAA): An individual possessing three basic sets of homologous chromosomes具有 3 个基本同源染色体组Phenotype of autotriploidsMore vigorous vegetative growth, profuse tillering, gigantic phenotype and high ovule abortion表型：营养生长旺盛，大量分蘖，巨大表型，高雌配子败育率

Cytological behavior细胞学行为

Morphological characteristics of autotetraploid同源四倍体的形态特征

Slowing in growth

Exhibiting dark green, large leaves

Reducing the number of tillers

增长缓慢 叶深绿色而大 减少分蘖数

Amphidiploid-- 双二倍体 the allotetraploid that contain the equivalent of genomes

derived from two separate species 双二倍体：是来源于两个不同物种的染色体组杂交形成

Amphidiploid—cotton双二倍体棉花

The origin of tobacco (N. tabacum)烟草的起源（普通烟草）

The origin of wheat (T. aestivum)小麦的起源（普通小麦）

Aneuploidy--the origin: nondisjunction非整倍体—染色体不分离

Aneuploidy is the organisms gain or lose one or more chromosomes Aneuploidy originates as the result of an error during meiosis 非整倍体是生物体获得或失去一个或多个染色体 非整倍体起源是减数分裂过程出现错误的结果

Aneuploidy and euploidy

Types of aneuploid非整倍体 的类型

Trisomic( 三体 ): 2n+1Monosomic ( 单体 ): 2n-1double trisomic ( 双三体 ):

2n+1+1double monosomic ( 双单体 ): 2n-1-1tetrasomic ( 四体 ): 2n+2nullisomic ( 缺体 ): 2n-2

Random chromosome segregation (AAa)染色体随机分离

Gene chromosomal location基因的染色体定位

Gene chromosomal location with trisomy Segregation ratio of self crossing F2 = 3 domianat:1 recessive

Phenotype ratio of test crossing offspring = 1 dominant:1 recessive

TrisomySegregation ratio of self crossing F2 ≠ 3 domianat:1 recessive Phenotype ratio of test crossing offspring ≠ 1 dominant:1 recessive

The karyotype of Down syndrome individual

Section 3 Changes in genetic material-- gene mutation遗传物质的改变 -- 基因突变

Gene mutation: The genetic variation at the level of the gene results in the change of alleles, which is also called the point mutation with a single base alteration

基因突变：基因内部所发生的从一种等位形式改变为另一种等位形式的变化，又称基因的点突变（ DNA 单个碱基所发生的替换、缺失所引起的突变）

Classification of point mutations点突变的类型

• 1. Base substution• A pair of bases substute for a pair of other bases• 1) Transition: A substution between the same category of base; that is

pyrimidine versus pyrimidine or purine versus purine• 2) Transversion: A substution between the different category of base;

that is pyrimidine versus purine• 2. Base instertion and deletion• The point mutation is due to a pair of bases inserting into or deleting

from DNA• 一、碱基替换：一对碱基替换另一对碱基所造成的突变• 1. 转换：同类碱基间的替换• 2. 颠换：不同类碱基间的替换• 二、碱基的增加及缺失

The molecular basis of mutaiton突变的分子效应

Mutation in coding region1. Synonymous mutation: Silent mutation, a codon mutates another codon for the same amino acid2. Missense mutation: A amino acid codon mutates another amimo acid codon3. Nonsense mutation: A amino acid code mutates a stop codon, leading to the activity loss of a polypeptide4. Frameshift mutation: The alteration of the whole DNA sequence from mutation to the stop condon is due to the insertion or deletion of a base or a fewMutation in non-coding regionPoint mutations often occur in the site binding regulatory protein发生在基因编码区的突变一、同义突变二、错义突变三、无义突变四、移码突变发生在基因非编码区的突变

The pattern of mutation at the level of DNA

The effect of the mutation on the organism突变对生物的影响

• Loss of function mutation: A mutation results in the reduction or loss of the protein activity

• Gain of function mutation: A mutation increases the activity of a protein and may confer novel phenotypes to a protein

• Reverse mutation: Back mutation, mutations either restore the original DNA sequence or alter other loci to gain functional compensation

• 功能丧失性突变：突变结果造成蛋白质活性下降或丧失• 获得功能突变：突变结果造成蛋白质活性增加，或获得新性状• 回复突变：突变通过重建设原 DNA 序列或在基因其他位点获得补偿

The induced mutation mechnism of point mutation点突变的诱变机制

• Induced mutation• Mutations are produced by various mutagen• 1. Base analogue• 5-bromouracil(5-BU), 2-aminopurine(2-AP)• 2. Base alteration• Alkylating agents, intercalating agents• 3. Base damge• Ultraviolet light, aflatoxin B1 • 4. Site specific mutagenesis• Spontaneous mutation• Those that just happen in nature, no specific agents are associated with

their occurrence. They often result from spontaneous DNA lesions, oxidative base lesions, errs in DNA copy and or so

• 诱发突变：碱基类似物、碱基改变、碱基损伤和位点专一性突变• 自发突变