Sp7 transgene zebravissen

• Biologie
• Middelbare school
• vwo
• Leerjaar 6

Sp7 transgenic zebrafish

Bone diseases

• Old population -> bone diseases
• Human experiments difficult
•  Using animal models
• Making bone visible
• Ability to test effects of pollutants, hormones, environment etc. on bone growth

Model organisms

• Zebrafish are conventient
• Fast reproduction
• Fast development
• Translucent embryo
• Conserved genes with humans 
• Bone diseases in humans can be researched using zebrafish
• Transgenic zebrafish

Genetic modification

Sp7 transcription factor is present in the osteoblasts (bone producing cells) of both zebrafish and humans. This makes zebrafish an excellent candidate to experiment on for research on bone growth of humans. A method has been developed to measure Sp7 activity based on Sp7:luciferase transgenic zebrafish. Luciferase is an enzyme that is originally found in fireflies, and is capable of producing light. The gene for this enzyme has been inserted after the promoter for Sp7. Therefore, wherever Sp7 is expressed, luciferase will also be expressed. When the substrate D-Luciferin and ATP are added, the Luciferase catalyzes a reaction that creates light. More light is produced the more luciferase is present. Since luciferase expression is directly correlated to Sp7 expression, the amount of light produced can be used as a measure to estimate Sp7 promoter activity, and therefore bone growth.

Question 1: Sp7 is a transcription factor that is present in bone producing cells. This transcription factor is able to regulate the expression of genes that are important for bone growth. Explain how a transcription factor is able to regulate gene expression. Use the terms "mRNA" and and "RNA polymerase" in your answer.

Answer 1

A transcription factor is a protein that binds to specific DNA sequences in the promoter region of a gene. Transcription factors can facilitate or disrupt  the binding of RNA polymerase to the DNA. This can make the transcription process, which is the conversion of DNA to mRNA, easier or more difficult.

Question 2: The gene that encodes for luciferase is inserted after the promoter for the Sp7 gene. Explain how this leads to the production of the luciferase enzyme only in places where the Sp7 transcription factor is also produced. Use the terms "transcription" and "translation" in your answer.

Answer 2

The luciferase gene is inserted after the Sp7 promoter, so it is only transcribed when the Sp7 promoter is active and simultaneously transcribes the Sp7 gene. This creates both luciferase mRNA and Sp7 mRNA, which are then translated into their respective proteins. These being the luciferase enzyme and the Sp7 transcription factor. This makes it so that luciferase enzyme is only present in cells that also produce Sp7 transcription factor.

Question 3: The luciferase gene was originally present in the light producing firefly. Using a recombinant DNA technique, this gene was inserted into the genome of the zebrafish. This created the transgenic light producing zebrafish. What is true about these transgenic organisms?

1. The fenotype resulting from this transgene could have also been achieved using artificial selection & selective breeding
2. These zebrafish are unable to pass the transgene to their offspring through their reproductive cells
3. The fenotype resulting from this transgene could have also been achieved with a recombinant DNA technique using a cisgene
4. These transgenic zebrafish have the luciferase gene present in their DNA even in cells where it is not expressed

Question 4: Using transgenic zebrafish as models for disease has many upsides as opposed to using humans. Still, there are some tradeoffs in accuracy when using this method. Give a reason as to why tests on transgenic zebrafish can not be fully extrapolated to humans.

Answer 4

1. Inserting a transgene can cause unexpected changes in the zebrafish, leading to unintended mutations or health issues, which might not be apparent and could complicate research results.

OR

2. While transgenic zebrafish have some similarity to humans, their biological differences from humans mean that results may not always directly translate to human treatments or outcomes.

Question 5: Using transgenes from glowing jellyfish, many different colors of glowing zebrafish have been made. These GloFish, while loved for their colors in many countries, they are banned in the EU due to laws regarding GMO's. Give at least two concerns/issues regarding GloFish.

Answer 5

1. If GMOs like GloFish are accidentally released into the wild, they could potentially disrupt natural ecosystems. For example, the glowing may affect predator-prey interactions.

2. The release of GMOs like GloFish could threaten biodiversity. GMO GloFish may breed with wild GloFish, potentially causing the spread of altered traits that could have unknown consequences.

3. The genetic modification of zebrafish for entertainment creates ethical concerns about whether it is justifiable to alter animals' genetics for human enjoyment, rather than for something urgent like disease research.

4.  The genetic modifications might cause health problems for animals, like a shorter lifespan or deformities, which is not in the best interest of the well-being of the zebrafish.

Discuss: do you think keeping GMO organisms recreationally as pets (not for research) should be legalized in the EU?

YES

NO

UNSURE