Mutant organisms What is a mutant organism An organism with a permanent change to its genome What are mutants used for in research Expression of a fluorescent protein in a single pair of neurons ID: 920458
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Slide1
FlyBuilder Module 1: Balancer Chromosomes in Drosophila Melanogaster
Slide2Mutant organisms
What is a mutant organism?
An organism with a permanent change to its genome
What are mutants used for in research?
Slide3Expression of a fluorescent protein in a single pair of neurons
MB308B>20X-UAS-IVS-CsChrimson-mVenus;
Janelia
Split-GAL4 collection, splitgal4.janelia.org
Mutant
Drosophila
are very cool.
Slide4MB308B driver line,
Janelia
Split-GAL4 collection (splitgal4.janelia.org)
Mutant
Drosophila
are very cool, and useful!
Slide5Mutant
Drosophila
are very cool, and useful!
There’s just one problem.
Slide6A B C D E F G H I J
A B C D E F G H I J
A B C D E F G H I J
A
B
C D E F G H I J
(
Recombination
)
Wildtype chromosomes
Chromosomes undergo meiotic recombination
Slide7A b C D E F G H I J
A B C D E F G H I J
A B C D E F G H I J
A
B
C D E F G H I J
(
Recombination
)
Heterozygous mutant chromosomes
Over time, mutation b will be lost.
Meiotic recombination can lead to mutation loss
Slide8A b C D E F G H I J
A B C D E F G H I J
Over time, mutation b will be lost.
Mutation b was…
Expensive, difficult and time-consuming to make
So useful to study ALL THE THINGS
The only one of its kind in the whole world
Heterozygous mutant chromosomes
Meiotic recombination can lead to mutation loss
Slide9Maintain mutations in fly stocks
Track
those mutations in progeny
A wildtype female
Drosophila melanogaster
Drosophila
balancer chromosomes allow you to:
Slide10A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Balancers are large multiply inverted chromosomes
Slide11A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B C D E F G H I J K L M N O P Q R S T U V
B C D E F G H I J K L M N O P Q R S T U V
E F G H I
P Q R S T U V
E F G H I
P Q R S T U V
B C D J K L
E F G H I
B C D J K L
E F G H I
T U V
M N O
B C
T U V
M N O
B C
Balancers are large multiply inverted chromosomes
Slide12A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B C D E F G H I J K L M N O P Q R S T U V
B C D E F G H I J K L M N O P Q R S T U V
E F G H I
P Q R S T U V
E F G H I
P Q R S T U V
B C D J K L
E F G H I
B C D J K L
E F G H I
T U V
M N O
B C
T U V
M N O
B C
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
(Original)
(Balancer)
Balancers are large multiply inverted chromosomes
Slide13A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
A B C D E F G H I J
A
B
C D E F G H I J
No balancer: b is lost.
Balancer chromosome: no recombination
A b C D E F G H I J
A B C D E F G H I J
B C D E F
Balancers prevent meiotic recombination
Slide14A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
An imaginary cross of balanced heterozygous mutants
A b C D E F G H I J
A B C D E F G H I J
B C D E F
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A b C D E F G H I J
Slide15A b C D E F G H I J
A B C D E F G H I J
B C D E F
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A b C D E F G H I J
1. Balancers contain a recessive lethal mutation
Slide16A b C D E F G H I J
A B C D E F G H I J
B C D E F
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A b C D E F G H I J
Recessive lethal mutations in the balancer ensure mutation presence in the population
1. Balancers contain a recessive lethal mutation
Slide17Markers confer visible, easily selected phenotypes.
A b C D E F G H I J
B C D E F
Example: Curly, not straight, wings
2. Balancers contain markers
Slide182. Balancers contain markers
A b C D E F G H I J
A B C D E F G H I J
B C D E F
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A B C D E F G H I J
B C D E F
A b C D E F G H I J
A b C D E F G H I J
Marker mutations allow you to identify genotype from phenotype
Slide19Eye color
Body color & size
Wing shape
Hair count, length and texture
Common markers affect…