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ZEBRAFISH IN
GENOME RESEARCH
Can you spot the difference?
yourgenome.org
WHAT IS A ZEBRAFISH?
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Danio rerio
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Small freshwater fish from
South Asia.
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4 cm long when fully grown.
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Common aquarium fish.
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Very easy to look after.
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WHAT IS A MODEL ORGANISM?
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Non-human species widely studied to understand human
disease.
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Model organisms are used when experimentation using
humans is unfeasible or unethical.
Can you think of a model organism?
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TYPES OF MODEL ORGANISM
Genetic
model organism
Experimental
model organism
Genomic
model organism
Good candidates for
genetic analysis.
Good candidates for
developmental biology.
Good candidates for
genome research.
Breed in large numbers.
Produce robust embryos that
can be easily manipulated
and studied.
Easy to manage genomes e.g.
small genome size or limited
number of repeats.
Have short generation times
so large scale crosses can be
followed over several
generations.
Genome is similar to a
human.
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WHY USE ZEBRAFISH?
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Small size.
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All major organs present within
5 days post fertilisation.
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Short generation time (3-4 months).
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Produces 300-400 eggs every
2 weeks.
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Translucent embryos.
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Lots of genome resources available.
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THE ZEBRAFISH EMBRYO
brain
eye
ear
heart
swim
bladder
muscle
block
segments
notochord
~3.5 mm
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MODELLING HUMAN CONDITIONS
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Zebrafish mutants have been produced to model
human diseases such as:
•
Alzheimer's disease
•
Congenital heart disease
•
Polycystic kidney disease
•
Duchenne muscular dystrophy
•
Malignant melanoma
•
Leukaemia
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FORWARD SCREENING FOR MUTANTS
P
ENU-treated male
+/+ female
x
F1
+/M
+/+
x
F2
+/+ (50%)
+/M (50%)
x
F3
+/+ (25%)
+/M (50%)
M/M (25%)
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REVERSE SCREENING FOR MUTANTS
Potential human
disease gene
Exciting gene
expression pattern
Gene of interest
Potential new
player in
developmental
pathway
Gene knockout
Phenotype analysis
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THE ACTIVITY
Identify differences between the wild type zebrafish and mutant zebrafish
-A
glossary is provided to help you with scientific terms
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FLASH CARDS & WORKSHEETS
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ANSWERS
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Answers – Image 1
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What’s the difference?
Embryo B has no eye
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Answers – Image 2
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What’s the difference?
Fish B is a lighter, golden colour compared to fish A.
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Answers – Image 3
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What’s the difference?
The body of fry B is curved. If you look closely you’ll also see that its
mouth is open. This is because it is unable to fully close its mouth as
its muscles are too weak.
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Answers – Image 4
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What’s the difference?
The zebrafish embryos in picture B look paler and are not stained red.
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Answers – Image 5
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What’s the difference?
There are bright green blobs in picture B.
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Answers – Image 6
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What’s the difference?
Embryo A has more blue dots than embryo B. The blue dots are
stained neutrophils moving towards a wound on the zebrafish fin.
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