Midterm 1 - Notes 3 (Part 2) Flashcards
What do null mutations in Pitx1 in mice do?
Disrupts multiple functions
What do null mutations in Pitx1 in mice lead to?
Lethality
Lethality
The ability/ capacity to cause death or serious harm or damage
- leads to a complete loss of function
What happens it you KO Pitx1 in mice? Why?
It is lethal, because you dont get hind limb development and it effects the neuro functions
Why do you use more micro-satellite markers?
To create a smaller region to observe where the mutation that causes the phenotype is
Is the Pel region sufficient to drive pelvic expression?
YES!!!
Transgenic
Denoting an organism that contains genetic material into which DNA from an unrelated organism has been artificially induced
What happened when they put an artificial transgenic gene into a fish that doesnt normally produce a spine?
The fish produced a spine
What did they use to track the gene?
GFP
GFP
Green Fluorescent Protein
What does Pel contain?
Contains a tissue specific enhancer driving pelvic expression of Pitx1
What happens to the fish if Pel is missing?
No spine will develop
What is Pitx1?
It is a transcriptional master regulator
Where is Pitx1 present? (2)
- Hind limb structures in mammals and in birds
2. Homologous pelvic structures in fish (sticklebacks)
When is Pitx1 lethal?
When it has a loss of function in mice
How did they know that loss of spine happened independently?
They used fish that were from 2 very different geographical locations
What were the 2 lakes they used?
- Pacific (BC lake)
2. Atlantic (Iceland lake)
When is the complementary approach usually used?
It is usually used to test if mutant phenotypes are caused by change in the same gene
What is the assumption in the complementary approach?
In both cases, phenotypes are caused by a single gene and is recessive
What is the principle of the complementary approach?
you take 2 fish with the same phenotype and you cross them and observe if the phenotype is present in the next generation
What happens if the WT is dominant over the recessive mutant allele?
Then the offspring will show normal phenotypes
What happens if the same phenotype is caused by the mutant?
The phenotype will remain the same
What happened when the Iceland fish and BC fish was crossed in F1?
All F1 had reduced pelvic structures
What were the 2 possible reasonings behind have all the F1 generation from Iceland and BC fish have reduced pelvic structures?
- Recessive mutations in same locus both in Iceland and BC
2. Independent dominant change in Iceland fish
What did it suggest when you crossed a pelvic spine fish with a non pelvic spine fish?
This suggests that there is no dominant mutation because if it was then there would be no pelvic spines
- but there was
What approach was used when comparing the 3 spine and the 9 spine stickleback?
The complementary approach
- crossed the 9 and 3 spine stickleback (interspecific crosses)
Can hybrids of the 9 and 3 spine stickleback have pelvic spines?
Yes
What was discovered between these 2 groups? (the 3 and the 9 spine stickleback)
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
What is the proper name for a 3 spine stickleback?
Gasterosteus
What is the proper name for a 9 spine stickleback?
Pungitius
