Fri, 27th July - Transgensic & knockout animals

Question 1

What is a Transgenic Animal?

Carries a foreign gene (or several foreign genes) deliberately inserted into its genome.

In addition to the gene itself, the DNA usually includes other sequences to enable it

• to be incorporated into the DNA of the host and
• to be expressed correctly by the cells of the host.

Answer 1

•Transgenic sheep and goats express foreign proteins in their milk.

GM - they have certain genes inserted so the milk is best suited to humans

•Foreign gene is inserted into host DNA:

Randomly (Foreign gene may disrupt an endogenous gene important for normal development, and the chance is about 10%)

In multiple copies

Question 2

What two ways are there to make Transgenic Animals?

Answer 2

1. Embryonic stem cell transformation
2. Inject gene into fertalised egg

Question 3

Embryonic stem cells used in order to….

Answer 3

insert foreign DNA into host

(Take sequence of gene from animal of interest and over expressing gene into host)

1. Take a super ovulating female and a stug agouti male In order for them to mate.

2. Inject female with hormones to make them over produce eggs.

3. And the reason why you do it is because you want as many blastocyst later as possible (As many chances of fertalisation as possible in order to when you inject that one animal you actually are using one animal/one female for the next generation of transgenic animals)

Treat one animal to reduce the number of animals used

3 DAYS LATER

4. After 3 days you have females that after successful reproduction they carry alot of blastocysts. After egg becomes fertalised they are on the path to uterus, as its on the path it starts dividing and then they reach the Blastocyst stage

Blastocyst: 2 layers.

1 = trophoblast (outside)

2 = Innercell mass (stem cells)

Trophoblast is supportive system

Stem cells have ability to differentiate and be manipulated to…

5. Extract Blastocyst in a petri dish, place fibroblasts on bottom of dish, start culturing them on feeder cells.

(Fibrocells provide proper chemical environment to allow bastocysts to divide further)

Stem cells divide so rapidly you have to transfer them to additional dishes to avoid ‘over crowding’