Zebrafish Flashcards
What is the scientific name for zebrafish?
Danio rerio
What type of water do zebrafish live in?
freshwater
Why zebrafish?
- vertebrate model
- eyes –>ocular development
- fins
__% protein-coding human genes are related to genes found in zebrafish
70%
Who was the founding father of zebrafish and what was his contribution?
George Streisinger • Major contributor to understanding frameshift mutations and the structure of the T4 phage genome • Fish hobbyist • Need a simple model: 1971 began working with zebrafish and took over 10 years to publish his first zf paper • Died during scuba diving accident (1984)
Who adopted Dr. Streisinger’s lab after he passed away?
Charles Kimmel, University of Oregon, Institute of Neuroscience
-continued the work using zebrafish as a model organism
What does ZFIN stand for?
Zebrafish information network
Zebrafish mutants _____ human diseases + examples
phenocopy
(ex. heart: contractility, rhythmicity, kidney: cysts, renal failure, gastrointestinal: colorectal cancer, diabetes, vasculature/blood: stroke, clotting)
Advantages of zebrafish
External fertilization with high fecundity (lots of babies)
• Transparent embryos
• Rapid development
• Regenerative model
• ‘Simple’ vertebrate system
• Genetic Manipulation Techniques
• Early stages passive diffusion : cardiovascular defects
• Biochemical studies :water soluble drugs/toxins
• Behavioral Assays
• Community
Disadvantages of zebrafish
• Vertebrate, but not a mammal (Aquatic [don’t have legs and arms, gills for oxygen] vs Human
physiology)
• Complex genome (many genes are duplicated)
•Aquatic habitat complicates colony maintenance
• Lacks some key organs
•Highly inbred, lab-dependent animals
•It’s a relatively new model system
• Fewer commercially antibodies
Developmental cycle of zebrafish (4 stages)
cleavage, gastrulation and epiboly, organogenesis, hatching
What are the labels of the embryo?
chorion (outside for protection), yolk (inside for nutrients), 4-cell stage embryo (attached to the yolk)
Explain cleavage to pharyngula stages
Cleavage (0.5 hpf, 2-cell): rapid divisions
Blastula (128-cell): divisions slow, genes transcribed
Epiboly (4 hpf): blastoderm spreads to cover yolk
Gastrulation (5 hpf): blastoderm develops into two layers by involution
Segmentation (10 -22 hpf): somites form, primary organs start to develop
Pharyngula (24 hpf - 48 hpf): can see blood islands, heart, eye, forebrain, midbrain/hindbrain, optic vesicle, and extension of somites
When does pigment start to develop?
Pigment development after 48 hours
Explain juvenile (30-44 dpf) and adult (90 dpf-2yrs) stages
Juvenile - standard length 10mm-14mm, adult fins, pigment, 12 teeth
Adults - 3-5cm
Zebrafish technique examples
-cloning, mapping, early transgenesis, large scale genetic screens, sequencing, transposon mediated mutagenesis, gene known down, gene editing
What is forward and reverse genetics?
Forward: have a phenotype looking for a gene
Reverse: have a gene looking for a phenotype
____ mediated ____ is commonly used to label and visualize cells
transposon (piece of DNA that randomly integrates DNA), transgenesis
What is transgenic labelling and expression constructs?
-can overexpress gene and look at effects in development
What does transgenic mean?
A transgenic, or genetically modified, organism is one that has been altered through recombinant DNA technology, which involves either the combining of DNA from different genomes or the insertion of foreign DNA into a genome
What are transgenic transplantations?
-used to trace cell movements in different environments ex. take human cell lines and inject into zebrafish to see how they behave in a different environment
We can use knock__ and knock__ methods in zebrafish
down, out
Other zebrafish techniques: chemical libraries, drug discovery, disease treatments
Toxicity Screens
• Water soluble toxins
• Correlate links between toxins and disease
Structure-activity relationships
• Repropose drugs to find new targets/therapies
• Modify drugs to screen for improvements or changes in target specificity
Phenotype-based whole-organism screening
• Induced disease states:
Knockdown/Knockout transgenics screens
(e.g.: MOs and CRISPR)
• Screen multiple targets and measure disease outcomes/identify targets
• Assess targets with High Throughput Screening/Sequencing
Give examples of how zebrafish behavioural tests are similar to mouse tests (anxiety, grouping)
Anxiety: put zebrafish in open field tank or light/dark tank (same test as mouse)
Grouping: fish will swim together (same test as mouse)
