Transgenic Mice

[kaoticbandito]

Hi there. I was wondering if someone would be willing to point me in the right direction on something. I need to propose an experiment for a class I'm taking. My idea is to create a transgenic mouse line that overexpresses a certain gene thought to be involved in Down Syndrome (DSCAM Down Syndrome Cell Adhesion Molecule). I understand the gist of how transgenic mice are created (knockouts, CRE/LOX...etc), but I can't figure out how I can accurately overexpress the specific gene to simulate the effect of having 3 copies of a chromosome, without actually having 3 full copies of the entire chromosome. Is it even possible to be that specific? Or is having a group of mice that overexpress the gene to varying degrees the best that one can hope to obtain? Any resource recommendations (e.g. books, websites, papers...etc) would be helpful. Thanks in advance for any help you can provide.

 

Chris

[TeleMad]

Not sure, but since this appears to be more theoretical than actual (you seem to be just coming up with ideas, not implementing them), ...

 

1) Instead of a full extra chromosome, couldn't you isolate the gene of interest and then keep trying to insert an extra copy of it into using some kind of a vector, then check phenotypes of the offspring to determine which ones actually incorporated an extra copy?

 

2) Couldn't you somehow change the promoter and other regulatory sites for the gene of interest so that the gene gets expressed much more often than normal?

 

3) At least in humans, Down Syndrome can be caused either by having an extra chromosome 21 (trisomy 21, because of nondisjunction) or by having a translocation of part of chromosome 21 (I believe to chromsome 14???). I believe the second type is familial Down Syndrome: couldn't you propose to either find or create individuals with the translocation?

[UncleAl]

You require government approval to experiment upon mammals. Diddling mammals is a pisser in any case. You would be much better off doing something creative with Xenopus eggs that are huge, abundant, and easy to diddle before and after fertilization. Aside from ethical research... why not take something like bright red Serratia marcescens

 

http://soils1.cses.vt.edu/ch/biol_4684/Microbes/Serratia.html

http://mic.sgmjournals.org/cgi/content/abstract/150/11/3547

 

inject some isolated genes or general DNA into eggs (admittedly, lots of eggs) and see if you can grow a red Xenopus?

 

http://www.southernscientific.com/bacteria_fungi.asp

Check out CHROMOGENIC BACTERIAL SET at the bottom

 

If you are going for Frankenfrogs you must certainly them in designer colors. Gene (over-)expression generally requires a promoter sequence tied to a normal metabolic event that is triggered and does not saturate. Then again, you might get lucky. Or, take a genomically-incremented egg before the first division, expose to colceamide to double chromosomes into a match, and hope the whole thing works out.

[kaoticbandito]

Thanks for the responses. Just FYI...this is just a mock grant proposal. I won't be creating any transgenics. Thanks for the help. Any other suggestions are appreciated.

 

Chris (Who now has 10 days to get this thing done)

[UncleAl]

The tree seed protein cassette is irrelevant to seed development as long as it fills the seed. Replace pine seed protein with human growth hormone or hemophilia protein factors. As long as you are growing a custom softwood forest for fiber (low lignin, or high lignin with high vanillin yield)) or construction (high lignin for strength and bio-resistance), why not have its pine cones be worth $5000 each?