Zebrafish

Question 1

What is the scientific name for zebrafish?

Answer 1

Danio rerio

Question 2

What type of water do zebrafish live in?

Answer 2

freshwater

Question 3

Why zebrafish?

Answer 3

• vertebrate model
• eyes –>ocular development
• fins

Question 4

__% protein-coding human genes are related to genes found in zebrafish

Answer 4

70%

Question 5

Who was the founding father of zebrafish and what was his contribution?

Answer 5

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)

Question 6

Who adopted Dr. Streisinger’s lab after he passed away?

Answer 6

Charles Kimmel, University of Oregon, Institute of Neuroscience
-continued the work using zebrafish as a model organism

Question 7

What does ZFIN stand for?

Answer 7

Zebrafish information network

Question 8

Zebrafish mutants _____ human diseases + examples

Answer 8

phenocopy
(ex. heart: contractility, rhythmicity, kidney: cysts, renal failure, gastrointestinal: colorectal cancer, diabetes, vasculature/blood: stroke, clotting)

Question 9

Advantages of zebrafish

Answer 9

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

Question 10

Disadvantages of zebrafish

Answer 10

• 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

Question 11

Developmental cycle of zebrafish (4 stages)

Answer 11

cleavage, gastrulation and epiboly, organogenesis, hatching

Question 12

What are the labels of the embryo?

Answer 12

chorion (outside for protection), yolk (inside for nutrients), 4-cell stage embryo (attached to the yolk)

Question 13

Explain cleavage to pharyngula stages

Answer 13

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

Question 14

When does pigment start to develop?

Answer 14

Pigment development after 48 hours

Question 15

Explain juvenile (30-44 dpf) and adult (90 dpf-2yrs) stages

Answer 15

Juvenile - standard length 10mm-14mm, adult fins, pigment, 12 teeth

Adults - 3-5cm

Question 16

Zebrafish technique examples

Answer 16

-cloning, mapping, early transgenesis, large scale genetic screens, sequencing, transposon mediated mutagenesis, gene known down, gene editing

Question 17

What is forward and reverse genetics?

Answer 17

Forward: have a phenotype looking for a gene
Reverse: have a gene looking for a phenotype

Question 18

____ mediated ____ is commonly used to label and visualize cells

Answer 18

transposon (piece of DNA that randomly integrates DNA), transgenesis

Question 19

What is transgenic labelling and expression constructs?

Answer 19

-can overexpress gene and look at effects in development

Question 20

What does transgenic mean?

Answer 20

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

Question 21

What are transgenic transplantations?

Answer 21

-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

Question 22

We can use knock__ and knock__ methods in zebrafish

Answer 22

down, out

Question 23

Other zebrafish techniques: chemical libraries, drug discovery, disease treatments

Answer 23

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

Question 24

Give examples of how zebrafish behavioural tests are similar to mouse tests (anxiety, grouping)

Answer 24

Anxiety: put zebrafish in open field tank or light/dark tank (same test as mouse)

Grouping: fish will swim together (same test as mouse)