上海交通大学：《微生物学 Microbiology》课程教学资源（双语课件）Lecture 10 Bacterial genetics（10.1）Mutation and Recombination

上泽充通大￥ Shanghai Jiao Tong University 1896 1920 1987 2006 How can we change information encoded in a gene? Lecture 10-1 Bacterial Genetics I.Mutation and Recombination Chapter 1o in 8 BROCK BIOLOGY OF MICROORGANISMS AI JIAO TONG UNI Chen Feng School of Life Science and Biotechnology, Shanghai Jiao Tong University http://micro.sjtu.edu.cn

1896 1920 1987 2006 Lecture 10-1 Bacterial Genetics I. Mutation and Recombination How can we change information encoded in a gene? Chapter 10 in BROCK BIOLOGY OF MICROORGANISMS Chen Feng School of Life Science and Biotechnology, Shanghai Jiao Tong University http://micro.sjtu.edu.cn

I.Mutation and Recombination 10.1 Mutations and Mutants Important concepts 圈Mutation变异突变 A heritable change in the base sequence of the genome of an organism @Mutantz变异株/型 A strain carrying such a heritable change @Wildtype野生型 A strain isolated from nature @Genotype基因型 A precise description of the genes an organism has @Phenotype表现型 The observable properties of an organism Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity 10.1 Mutations and Mutants Mutation变异/突变 • A heritable change in the base sequence of the genome of an organism Mutant变异株/型 • A strain carrying such a heritable change Wildtype野生型 • A strain isolated from nature Genotype基因型 • A precise description of the genes an organism has Phenotype表现型 • The observable properties of an organism Important concepts I. Mutation and Recombination

Designations in microbial genetics遗传学表示方式 Genotype Three lowercase letters followed by a capital letter (all in italics) ·hisc ©Gene's product A capital letter followed by two lowercase letters and then a capital letter ·HisC,RecA @ Phenotype A capital letter followed by two lowercase letters,with either a plus or minus superscript to indicate the presence or absence of that property ·Hist,His ·Amp,Amp Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity Designations in microbial genetics 遗传学表示方式 Genotype • Three lowercase letters followed by a capital letter (all in italics) • hisC Gene’s product • A capital letter followed by two lowercase letters and then a capital letter • HisC, RecA Phenotype • A capital letter followed by two lowercase letters, with either a plus or minus superscript to indicate the presence or absence of that property • His+ , His- • Ampr , Amps

10.1.1 Isolation of mutants:Screening Versus Selection 突变株的分离 圈Nonselectable mutants-pigment mutation非选择性变异株 mutants with no advantage or disadvantage over parental cells when growing under artificial conditions. The only way to find a nonselectable mutant is to screen a large population of the bacterium筛选 Selectable mutants-drug resistance mutation选择性变异株 mutants with an advantage under certain environmental conditions, so the progeny of the mutant cell are able to outgrow and replace the parent cells Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity 10.1.1 Isolation of mutants: Screening Versus Selection 突变株的分离 Nonselectable mutants-pigment mutation非选择性变异株 • mutants with no advantage or disadvantage over parental cells when growing under artificial conditions. • The only way to find a nonselectable mutant is to screen a large population of the bacterium筛选 Selectable mutants-drug resistance mutation选择性变异株 • mutants with an advantage under certain environmental conditions, • so the progeny of the mutant cell are able to outgrow and replace the parent cells

Nonselectable Mutant Example非选择性突变株 (b) 2012 Pearson Education.Inc. Pigmented mutants and nonpigmented mutants of Aspergillus.The wildtype has a green pigment.The white mutants make no pigment, whereas the yellow mutants cannot convert the pigment to the normal color

Chen Feng, Shanghai Jiao Tong Univerity Nonselectable Mutant Example非选择性突变株 Pigmented mutants and nonpigmented mutants of Aspergillus. The wildtype has a green pigment. The white mutants make no pigment, whereas the yellow mutants cannot convert the pigment to the normal color

TONG UN Selectable Mutant Example可选择的突变株 (a) 2012 Pearson Education,Inc. Antibiotic-resistant mutants within the inhibition zone of an antibiotic assay disc.抗生素抗性突变株 Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity Selectable Mutant Example 可选择的突变株 Antibiotic-resistant mutants within the inhibition zone of an antibiotic assay disc.抗生素抗性突变株

Screening vs.Selection Screening is to observe all the cells in a population to identify mutants from parent cells筛选：从群体中观察所有细胞， 从中挑选出变异株 Selection is to grow population under certain conditions so that mutants will grow faster than parent cells (eventually they become the majority or even the only cell types in the population).选择：在特定培养条件中使变异株成为优势株 或唯一生长的菌株 Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity Screening vs. Selection Screening is to observe all the cells in a population to identify mutants from parent cells筛选：从群体中观察所有细胞， 从中挑选出变异株 Selection is to grow population under certain conditions so that mutants will grow faster than parent cells (eventually they become the majority or even the only cell types in the population). 选择：在特定培养条件中使变异株成为优势株 或唯一生长的菌株

Selection for mutants变异株的选择方法 Positive selection for mutants Drug resistance-mutants which are resistant to some antibiotic can be selected by growing on medium containing this drug药物抗性突变株可以在含该药物的培养基中生 长而被选择出来。 Negative selection which is not for the mutant but against parental type ·Penicillin selection青霉素选择法 Penicillin only kill actively growing cells Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity Selection for mutants 变异株的选择方法 Positive selection for mutants • Drug resistance-mutants which are resistant to some antibiotic can be selected by growing on medium containing this drug药物抗性突变株可以在含该药物的培养基中生 长而被选择出来。 Negative selection which is not for the mutant but against parental type • Penicillin selection青霉素选择法 • Penicillin only kill actively growing cells

上泽充通大￥ Shanghai Jiao Tong University 1896 1920 1987 2006 10.1.2 Isolation of Nutritional Auxotrophs:Replica plating method and Penicillin Selection 营养缺陷型的分离 VERS 平板复制法与青霉素负选择法

1896 1920 1987 2006 10.1.2 Isolation of Nutritional Auxotrophs: Replica plating method and Penicillin Selection 营养缺陷型的分离: 平板复制法与青霉素负选择法

Nutritional mutation营养型突变 圈Auxotroph营养缺陷型 A nutritional mutant that has a requirement for a growth factor Prototroph原养型 The wildtype parent for a nutritional mutation Chen Feng,Shanghai Jiao Tong Univerity

Chen Feng, Shanghai Jiao Tong Univerity Nutritional mutation 营养型突变 Auxotroph营养缺陷型 • A nutritional mutant that has a requirement for a growth factor Prototroph原养型 • The wildtype parent for a nutritional mutation