MUTATION DETECTION SYSTEM ENVIRONMENTAL GENETICS

1. PREPARED BY
NAVEENA GIRISH
DEPARTMENT OF PLANT SCIENCE
CENTRAL UNIVERSITY OF KERALA

2. 2 TYPES
VISIBLE SLC
BIOCHEMICAL
SLC
WIDELY USED
Uses 5 or 7 loci
Uses up to 20
enzymes

3.  T O DETECT QUANTITATIVE MUTATION IN MAMMALIAN
GERMLINE CELLS
A visible specific locus mutation is a genetic change that
alters factors responsible for coat color and other visible
characteristics of certain mouse strains
 principle
 to cross individuals who differ with respect to the genes
present at certain specific loci, so that a genetic alteration
involving the standard gene at any one of these loci will
produce an offspring detectably different from the standard
heterozygote.
FEMALE
HOMOZY
GOUS
MALE +
TEST
REAGENT
PROGENY
SCREENING FOR
MUTATION

4. BIOCHEMICAL SPECIFIC LOCUS TEST
A biochemical specific locus mutation is a genetic change
resulting from a DNA lesion causing alterations in proteins that
can be detected by electrophoresis methods.
The principle of the MBSL is that heritable damage to the
genome can be detected by electrophoresis analysis of proteins in
the tissues of the progeny of mice treated with germ cell
mutagens
Treated males are then mated to untreated females to produce
F1 progeny. Both blood and kidney samples are taken from
progeny for electrophoresis analysis. Up to 33 loci can be
examined by starch-gel electrophoresis and broad-range
isoelectric focusing. Mutants are identified by variations from
the normal electrophoresis pattern. Presumed mutants are bred
to confirm the genetic nature of the change.

5. Single generation & visual detection is used to identify
mutation – SO USEFUL
OFFSPRING EXAMINATION
BIRTH AND WEANING
TISSUE SAMPLING
ELECTROPHORESIS
MUTANT IDENTIFICATION
BLOOD -6 LOCI
KIDNEY – 27 LOCI

6. AMES TEST
Industrial chemicals potentially harmful
to humans
We can know it using lab animals
But it is time consuming and expensive
Bruce Ames
1974
PRINCIPLE
Damage to DNA mutation Cancer
90% carcinogen = mutagen
Mutation in bacteria = carcinogenesis in humans

7. I used Salmonella
typhimurium
with dna repair
system
inactivated and
defects in
lipopolysacharide
4 strains used

8.  carcinogenic compounds in hair dyes removed by the help of
Ames test

9. One of the four strains detect base pair substitutions
Other three detect frameshift mutation

10. DROSOPHILA
MELANOGASTER
DEFINED MUTATION RATE
INTIAL EXPERIMENTS WAS
FAIL
BUT 1927 BERLIN
CONFERENCE HE SURPRISED
OTHERS
X- RAYS INDUCES
MUTATION
7 YEARS
BUT HE SAID NO QUALITATIVE DIFFERENCE BETWEEN SPONDANEOUS AND
INDUCED MUTATIONS

11. ClB METHOD – TO STUDY MUTATIONS
HAPPENING ON X CHROMOSOME

12. He received Nobel prize in 1945

13. MULERS -5 METHOD

14. TO TEST X CHROMOSOME
The progeny of F2 generation indicate
whether or not lethal mutations occurred on
males x chromosomes
If lethal mutation occurred on wild type male
– it die
C – prevents crossing over & recombination
So lethality reside in one chromosome itself
C – prevents cross over
There is 2 markers
B – bar eye
Wa for apricot

15.  recessive mutation can only express if
there is homozygosity
Attached x – to screen F1 mutations on x
of males
X^X – REPRESENTATION
Compound chromosome 2 x chromosome
attached
Inheritance as single unit
X^X female
ATTACHED X CHROMOSOME