Transcript Campbell Greg fruit fly wing genetics Sci Proj 2010

Identifying genes that control
wing shape in flies
Gregory Campbell
Central Catholic High School
Pittsburgh
In narrow (nw) mutants the wing is narrow
Wild-type
narrow (nw)
The Nw protein is required to
make the wing wide
Nw protein
Wild-type
nw mutant
• How does it do this?
• We don’t know how narrow protein functions
• It is secreted from wing cells - looks like a
protein that binds to other proteins
Wings during metamorphosis in the fly pupal stages
Increasing age
During metamorphosis in the
wild-type pupa, normal wings
become narrower when cells
move in between each other.
Wings during metamorphosis in the fly pupal stages
Increasing age
In nw mutants the wings become
too narrow when cells move in
between each other too much.
Hypothesis
• Protein X: helps make the wing the right shape by making them
move in between each other
• If Protein X becomes overactive the wing becomes narrow
• Possibility 1: Narrow binds to Protein X to suppress function
• Possibility 2: Narrow binds to protein Y, interacting to suppress to
X function
Nw protein
Protein X
Protein X
(overactive)
Protein X
Protein Y
Nw protein
Reducing the amount of X in a nw mutant should make wing less narrow
If Y exists, reducing Y in a nw mutant may make the wing more narrow
So how to do you find genes x and y?
Test mutations in all the genes in the fly? Take forever!
Alternative: Use Deficiencies (Df)
• Dfs = small deletions in a chromosome
• Each deletes a different region of a chromsome
• Each Df may include 10-50 genes
• 200 Dfs cover almost all of the chromosomes
Df(2L)ED250
Studies done before I started:
18 Dfs identified that which make a narrow mutant wing
narrower or wider, e.g. Df(2L)ED250 and Df(2L)N22-14
nw[D] Df(2L)N22-14
nw[D]/+
nw[D]/Df(2L)ED250
Deficiency Df(2L)ED250 makes the narrow wing narrower
nw[D]/+
nw[D]/Df(2L)ED250
24F-25A region of the chromosome
Is one
of these
gene y?
Test more Dfs in 24F-25A region
Method
• Cross nw[D] to Df
• Pick out nw[D]/Df flies
• Pull wings off and mount on microscope slides
• Take picture
• Measure length and width of wings
• Compare l:w of nw[D]/Df to nw[D]/+
• Use statistical test (t-test) to find if difference is likely to be real
Results for 24F-25A region
Results on chromosome map
Blue = interacts (makes wing narrower)
Red = no effect (same as nw[D]/+)
Which gene?
Dp mutants have defective wings
wild-type
dp[olv1]
(no Dp protein)
Why dp mutant wings look like this is not understood
Dp protein is very large and is found on the outside of cells
Do dp mutants change the shape of nw mutant wings like the Df?
Do mutations in dp
interact with nw?
nw[D]/+
nw[D]/dp[ov1]
Yes!
nw[D]/dp[olvR]
(50% Dp protein)
Conclusion
• Identified dp as a gene that interacts with nw
• Dp may be protein Y: results suggest Nw may function
with Dp to stop the wing becoming too narrow
Nw protein
Protein X
Protein X
Protein Y
Nw protein
• but it must be more complicated than this..
Shape changes in nw mutants are similar
to those in vertebrate embryos
Increasing age
Frog embryos
Convergent
extension
Wings during metamorphosis in pupa
Increasing age
Too much
convergent
extension?