ZEBRAFISH IN GENOME RESEARCH Can you spot the
ZEBRAFISH IN GENOME RESEARCH Can you spot the difference?
WHAT IS A ZEBRAFISH? - Danio rerio - Small freshwater fish from South Asia. - 4 cm long when fully grown. - Common aquarium fish. - Very easy to look after.
WHAT IS A MODEL ORGANISM? - Non-human species widely studied to understand human disease. - Model organisms are used when experimentation using humans is unfeasible or unethical. Can you think of a model organism?
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.
WHY USE ZEBRAFISH? - Small size. - All major organs present within 5 days post fertilisation. - Short generation time (3 -4 months). - Produces 300 -400 eggs every 2 weeks. - Translucent embryos. - Lots of genome resources available.
THE ZEBRAFISH EMBRYO brain eye ear heart swim bladder muscle block segments ~3. 5 mm notochord
MODELLING HUMAN CONDITIONS - 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
FORWARD SCREENING FOR MUTANTS P ENU-treated male +/+ female x F 1 +/M +/+ x F 2 +/+ (50%) +/M (50%) x F 3 +/+ (25%) +/M (50%) M/M (25%)
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
THE ACTIVITY Identify differences between the wild type zebrafish and mutant zebrafish - A glossary is provided to help you with scientific terms
FLASH CARDS & WORKSHEETS
ANSWERS
ANSWERS – IMAGE 1 - What’s the difference? Embryo B has no eye
ANSWERS – IMAGE 2 - What’s the difference? Fish B is a lighter, golden colour compared to fish A.
ANSWERS – IMAGE 3 - 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.
ANSWERS – IMAGE 4 - What’s the difference? The zebrafish embryos in picture B look paler and are not stained red.
ANSWERS – IMAGE 5 - What’s the difference? There are bright green blobs in picture B.
ANSWERS – IMAGE 6 - 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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