Midterm 1 - Notes 3 (Part 2)

Question 1

What do null mutations in Pitx1 in mice do?

Answer 1

Disrupts multiple functions

Question 2

What do null mutations in Pitx1 in mice lead to?

Answer 2

Lethality

Question 3

Lethality

Answer 3

The ability/ capacity to cause death or serious harm or damage
- leads to a complete loss of function

Question 4

What happens it you KO Pitx1 in mice? Why?

Answer 4

It is lethal, because you dont get hind limb development and it effects the neuro functions

Question 5

Why do you use more micro-satellite markers?

Answer 5

To create a smaller region to observe where the mutation that causes the phenotype is

Question 6

Is the Pel region sufficient to drive pelvic expression?

Answer 6

YES!!!

Question 7

Transgenic

Answer 7

Denoting an organism that contains genetic material into which DNA from an unrelated organism has been artificially induced

Question 8

What happened when they put an artificial transgenic gene into a fish that doesnt normally produce a spine?

Answer 8

The fish produced a spine

Question 9

What did they use to track the gene?

Answer 9

GFP

Question 10

GFP

Answer 10

Green Fluorescent Protein

Question 11

What does Pel contain?

Answer 11

Contains a tissue specific enhancer driving pelvic expression of Pitx1

Question 12

What happens to the fish if Pel is missing?

Answer 12

No spine will develop

Question 13

What is Pitx1?

Answer 13

It is a transcriptional master regulator

Question 14

Where is Pitx1 present? (2)

Answer 14

1. Hind limb structures in mammals and in birds

2. Homologous pelvic structures in fish (sticklebacks)

Question 15

When is Pitx1 lethal?

Answer 15

When it has a loss of function in mice

Question 16

How did they know that loss of spine happened independently?

Answer 16

They used fish that were from 2 very different geographical locations

Question 17

What were the 2 lakes they used?

Answer 17

1. Pacific (BC lake)

2. Atlantic (Iceland lake)

Question 18

When is the complementary approach usually used?

Answer 18

It is usually used to test if mutant phenotypes are caused by change in the same gene

Question 19

What is the assumption in the complementary approach?

Answer 19

In both cases, phenotypes are caused by a single gene and is recessive

Question 20

What is the principle of the complementary approach?

Answer 20

you take 2 fish with the same phenotype and you cross them and observe if the phenotype is present in the next generation

Question 21

What happens if the WT is dominant over the recessive mutant allele?

Answer 21

Then the offspring will show normal phenotypes

Question 22

What happens if the same phenotype is caused by the mutant?

Answer 22

The phenotype will remain the same

Question 23

What happened when the Iceland fish and BC fish was crossed in F1?

Answer 23

All F1 had reduced pelvic structures

Question 24

What were the 2 possible reasonings behind have all the F1 generation from Iceland and BC fish have reduced pelvic structures?

Answer 24

1. Recessive mutations in same locus both in Iceland and BC

2. Independent dominant change in Iceland fish

Question 25

What did it suggest when you crossed a pelvic spine fish with a non pelvic spine fish?

Answer 25

This suggests that there is no dominant mutation because if it was then there would be no pelvic spines
- but there was

Question 26

What approach was used when comparing the 3 spine and the 9 spine stickleback?

Answer 26

The complementary approach

- crossed the 9 and 3 spine stickleback (interspecific crosses)

Question 27

Can hybrids of the 9 and 3 spine stickleback have pelvic spines?

Answer 27

Yes

Question 28

What was discovered between these 2 groups? (the 3 and the 9 spine stickleback)

Answer 28

No complementation between these 2 changes

• phenotype caused by changes in same genomic region in 3 and 9 spine stickleback
• would expect that it is a recessive change
• Pitx1 is effected

Question 29

What is the proper name for a 3 spine stickleback?

Answer 29

Gasterosteus

Question 30

What is the proper name for a 9 spine stickleback?

Answer 30

Pungitius