to get the file

Handai Cyber University

Introduction of Biotechnology No.19: Microbial Genetics Fundamentals Graduate School of Engineering, Osaka University Graduate School of Information Science, Osaka University International Center for Biotechnology, Osaka University 1

Hello! My name is Satoshi Harashima.

Scientific interest: Yeast Genetics, Yeast Genomics Hobby: Listening and playing Jazz music Date of birth: 21 May 1949 ; Birthplace: Ehime, Japan

2

No.19 Microbial Genetics Fundamentals

I. Brief history of microbial genetics II. Principle of genetic analyses III. Yeast genetics IV. Bacterial genetics

V. Fungal genetics 3

I. Brief history of microbial genetics

• What is genetics • Why do we study genetics? • Advantage of classical genetics • Feature of microbial materials 4

What is genetics? Genetics is the study of heredity Heredity is the phenomenon whereby biological traits are transmitted from one generation to another. Why do children resemble their parents? Genetics is the scientific discipline to study physical and molecular organization underlying hereditary process.

5

Why do we study genetics?

Genetics occupies an important position in modern biological sciences

Genetics is absolutely necessary for breeding of organisms industrially used for biotechnology

6

Major advantages of classical genetic approach

○ Mutants can be isolated and characterized without any a priori understanding of the molecular basis of the function. ○ To determine how many genes are involved in a function? ○ To find other genes whose products may interact either physically or functionally with the products of these genes.

7

1865: Genetics begun with Mendel’s work Plant 1900: Rediscovery of Mendel’s law

Untill1940: Fly and Corn as experimental materials for genetic study 1940 〜：Microorganisms start to be used for genetic study 8

Microorganisms used for genetic studies Escherichia coli Neurospora crass Aspergillus nidulans Saccharomyces cerevisiae

9

Feature of microbial genetics ○ Short generation time ○ Accumulated knowledge for cultivation method (suitable for Biochemistry) ○ Defined media can be used (suitable for Biochemical genetics) ○ Easy mutant-hunting due to haploidy ○ A large number of sample can be dealt with (suitable for statistical analysis)

10

Quiz 1 Do following characters give an advantage of microorganisms in genetic study ?

1) Invisible cell by eyes 2) Short life span 3) Haploid vegitative cells 4) Large number of cells in small space 11

II. Principle of genetic analyses

III. Yeast genetics • Isolation of mutants • Dominance-recessiveness test • Complementation test • Epistasis-hypostasis test • Linkage analysis 12

Essential approaches for genetic analyses 1) Isolation of mutants 2) Dominance-recessiveness test 3) Complementation test（Recombination test） 4) Epistatic-hypostatic test 5) Linkage analysis

13

Isolation of mutants The most important step in genetic research. Genetics starts with isolation of mutants. Gene nomenclature is different from organisms to organisms

HIS3: wild type allele for Saccharomyces cereivisiae his3-1 : mutant allele:

Locus number

Allele number

Gene name (Three letter) Recessive mutation: lower case Dominant mutation: upper case 14

Dominance-recessiveness test Cross Mutant (His-)

HISX

hisX

Wild type (His+)

Diploid hisX/HISX If diploid exhibits If His+ phenotype If His- phenotype Mutation is Recessive

Mutation is Dominant

Loss of function?

Gain of function? 15

Complementation test (for recessive mutation) Mutant X (His-)

hisX

Diploid

Mutant Y (His-)

Cross

hisY

hisX hisY

If diploid exhibits His- phenotype

Mutation occurs in the same gene

hisX = hisY

Mutant X (His-)

hisX

Diploid

Mutant Y (His-)

Cross

hisY

hisX + + hisY

If diploid exhibits His+ phenotype

Mutation occurs in different gene

hisX ≠hisY

We could infer how many genes are involved in a particular biological phenomenon. 16

Epistasis-hypostasis test Cross

phoX Mutant (Uninducible rAPase production)

Diploid

phoY Mutant (Constitutive rAPase production)

Meiotic segregant harboring phoX phoY double mutations phoX phoY If phoX phoYs double mutant shows Uninducible phenotype phoX is epistatic

Constitutive phenotype phoY is epistatic 17

Linkage analysis through meiosis

Deleted based on copyright concern.

18

Linkage analysis 2 3 1 4 Spore 1 Spore 2 Spore 3 Spore 4

Cross: HIS3 LEU2 x his3 lue2

PD

NPD

T

HIS3 LEU2 HIS3 LEU2 his3 leu2 his3 leu2

his3 LEU2 his3 LEU2 HIS3 leu2 HIS3 leu2

HIS3 LEU2 HIS3 leu2 his3 LEU2 his3 leu2

Random assortment Linkage Centromere linkage

HIS3 his3 Recombination

1 >1 1

: : :

1