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. Image: Wikimedia commons/Marribio2
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 Images: Wellcome Trust Sanger Institute
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. Image: TBC
The zebrafish embryo brain ear muscle block segments swim bladder eye heart notochord ~3.5 mm
Zebrafish and human disease • 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 x F1 x F2 x F3
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 wildtype zebrafish and mutant zebrafish. • A glossary is provided to help you with scientific terms. Image: Rodrigo Young, University College London
Image 1 What’s the difference? Embryo B has no eye. Image: Rodrigo Young, University College London
Image 2 What’s the difference? Fish B is a lighter, golden colour compared to fish A. Image: Keith C. Cheng, Penn State College of Medicine and Wellcome images
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. Image: Elisabeth Busch, Wellcome Trust Sanger Institute and Lehtokari et al 2008, European Journal of Human Genetics
Image 4 What’s the difference? The zebrafish embryos in picture B look paler and are not stained red. Image: Ana Cvejic, Wellcome Trust Sanger Institute
Image 5 What’s the difference? There are bright green blobs in picture B. Image: Elisabeth Busch, Wellcome Trust Sanger Institute
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. Image: Ana Cvejic, Wellcome Trust Sanger Institute