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Miniprep for SEAP and GFP
Protocol: Miniprep
The slim tubes can be centrifuged in the machine in front of the "Gel hood", at 4000 rpm for 10 min. The fatter ones, in the E. coli centrifuge by the fridge (the tip can be left inside, since it floats).
Pellets resuspended with RNase containing buffer (Resuspension Buffer R3, from Invitrogen, equivalent to Buffer P1 from Qiagen, in Sowmya's box in the fridge). Note: keep the buffer in ice if you are not bringing it back to the fridge for some minutes.
We then use the QIAGEN QIAprep Spin Miniprep Kit with their protocol (page 22) and a microcentrifuge.
Only 4 of the readouts cultures in Falcon tubes have grown: S2.1, S3.1, G3.1 and G4.2.
- S2.1: SEAP + L5 1:2
- S3.1: SEAP + L5 1:3
- G3.1: eGFP + L6 1:3
- G4.2: eGFP + L6 1:4
Minipreps have been made with these cultures.
Nanodrop shows concentrations of around 150 ng/µl.
Control of Minipreps: digestion
Protocol: Restriction site digestion
- Look for the best pair of restriction sites, ideally with similar digestion temperatures and times.
- NEBcutter for finding cutting enzymes.
- Double Digest Finder for the parameters.
- Calculate the amounts required of:
- DNA
- Buffer (usually from 10x to 1x)
- BSA, if needed (usually from 100x to 1x)
- Enzymes (depends on the amount of DNA)
- Water
- Get the recommended buffer (and BSA if needed) from the freezer and let defreeze.
- Mix all the ingredients, except DNA, in a tube.
- Note: Enzymes should stay no longer than a couple of minutes out of the freezer. Don't touch the bottom of the tubes! Don't vortex!
- Distribute the mix in as many tubes as DNA samples and add the DNA.
- Keep in the Thermomixer at the recommended temperature.
Sowmya's recommended amounts (50 µl total solution):
- 5 µl of 10x buffer
- 0.5 µl of 100x BSA
- 1 µl of each enzyme
- 5 µl of DNA
- 37.5 (up to 50 µl) of water.
Protocol based on what was done on July the 4th.
We ran some digestions of the ligated plasmids to see if the bands they would yield corresponded to what we expected. We digested every culture miniprep with the same enzymes.
Using:
- HindIII and MfeI, 1 µl of each
- 5 µl of Buffer N2
- 0.5 µl of BSA
- 37.5 µl of water
- 5 µl of DNA (around 750 ng)
The first 4 points mixed in a master mix, then DNA added.
Control of Minipreps: gel electrophoresis
Protocol: Gel Electrophoresis
Agarose concentration depends on the size of the DNA to be run. We will mostly use 1%.
VOL is the desired volume of gel in ml:
CH Lab
- Add 0.01*VOL g of agarose to a clean glass bottle.
- Pour VOL/50 ml of 50xTAE in a graduated cylinder. Fill up to VOL ml with di water.
- Add the resulting VOL ml of 1xTAE to the glass bottle with agarose.
- Microwave, at 7, the bottle (loose cap!) until it boils.
- Carefully remove bottle (can be super heated!) and check for the total absence of particles. Microwave again if needed.
- Prepare a gel box, with comb, and fill it up with the agarose solution (maybe not the whole solution is needed).
- Add 0.05 µl per ml of gel in the box of Red Gel (it's in the iGEM drawer) and stirr until disolved.
- Wait until cold and solidified.
- Carefully remove comb.
- Place the box in the electrophoresis chamber.
- Fill up the electrophresis chamber with 1x TAE buffer.
- Add blue dye to the DNA samples (6x loading buffer, that is 10 µl in 50 µl of DNA solution).
- Inject 30 µl of ladder marker in the first well (that's 1 µg of DNA).
- Inject 60 µl of each DNA solution in the other wells.
- Set voltage to 70-90 V and run for 30-40 min, or until the dye reaches the last 25% of the gel length (DNA travels from - to +).
- Place the gel under the camera, cover, turn UV on and take photos!
Preparing the ladder:
- get 1kb ladder DNA from the freezer (500 µg/ml).
- for 30 charges, 30 µl per charge, we need 900 µl:
- 60 µl of 1kb ladder DNA
- 150 µl of dye (6x loading buffer)
- 690 µl of water
BM Lab
In this lab the gels are slightly different. The total volumes for the small, the medium and the large gel are respectively 60ml, 80ml and 90ml. As we use 0.5x TAE buffer instead of 1x, we can use higher voltages (170V seems to work fine). The gel should run 20-40 minutes, not more. As the gel is thinner, load less DNA (up to ~10ul).
Small gel, 50 ml in total:
- 0.5 g of agarose
- 1 ml of TAE
The expected bands are:
- For SEAP 4108 and around 1600 bp
- For eGFP 4108 and around 750 bp
- Gel picture
From what we observe, the ligated plasmids are actually not what we expected them to be. Something went wrong somewhere, either in the PCRs, either during the ligations.
PCRs
Protocol: PCR
PCR is a reaction that makes it possible (and relatively easy) to amplify
a certain region of DNA. The first step is the selection of that region
(and the design of the relevant primers). Primer design can be done by hand, or by
using our Primer Design Helper. Once
done, order the primers (in our case, we ordered from them IDT).
When you've received the primers, prepare them and make sure you've got your PCR kit (we used the "Phusion® High-Fidelity DNA Polymerase"). Start preparing your master mix, the composition for one tube is:
1X Mastermix 20μl reaction, add in this order
| Reagent | Volume [μl] |
|---|---|
| Water | Complete to total volume of 20μl |
| HF-Buffer (5x) | 4 |
| DMSO (optional) | 0.6 |
| dNTPs | 0.4 |
| Forward primer (50μM) | 0.2 |
| Reverse primer (50μM) | 0.2 |
| Template (10ng/μl) | 0.5 |
| Phusion HF polymerase | 0.2 |
Prepare one or two extra tubes-worth of reagent (you'll use some liquid on the walls of your tips).
Once you've finished, you should run the resulting products on a gel to check if everything went as planned.
Tips
- Thaw the HF-Buffer, DMSO and dNTPs before making the mastermix.
- Avoid taking the Phusion-HF polymerase out of the freezer (only take it out briefly when you need to add it).
- If the reactions have different primers and/or template, add the polymerase right after the dNTPs, split the mastermix and add the rest.
- Don't forget positive and negative controls
- Primers should have similar Tms (less than 5°C).
- Primer Tm calculation is a less exact science than it should be (just test several tools and compare their results). If you're not sure what the correct Tm is, consider using a gradient PCR.
- Avoid primers with strong secondary structures.
- PCR can introduce mutations. Don't forget to sequence your final product (this could be your final plasmid): you really don't want to lose a few weeks because of a "corrupt" plasmid.
A new PCR was performed on LovTAP in an attempt to add the restriction sites we need to ligate it into pMP. The protocol was standard.
Gel electrophoresis on every PCR product
Protocol: Gel Electrophoresis
Agarose concentration depends on the size of the DNA to be run. We will mostly use 1%.
VOL is the desired volume of gel in ml:
CH Lab
- Add 0.01*VOL g of agarose to a clean glass bottle.
- Pour VOL/50 ml of 50xTAE in a graduated cylinder. Fill up to VOL ml with di water.
- Add the resulting VOL ml of 1xTAE to the glass bottle with agarose.
- Microwave, at 7, the bottle (loose cap!) until it boils.
- Carefully remove bottle (can be super heated!) and check for the total absence of particles. Microwave again if needed.
- Prepare a gel box, with comb, and fill it up with the agarose solution (maybe not the whole solution is needed).
- Add 0.05 µl per ml of gel in the box of Red Gel (it's in the iGEM drawer) and stirr until disolved.
- Wait until cold and solidified.
- Carefully remove comb.
- Place the box in the electrophoresis chamber.
- Fill up the electrophresis chamber with 1x TAE buffer.
- Add blue dye to the DNA samples (6x loading buffer, that is 10 µl in 50 µl of DNA solution).
- Inject 30 µl of ladder marker in the first well (that's 1 µg of DNA).
- Inject 60 µl of each DNA solution in the other wells.
- Set voltage to 70-90 V and run for 30-40 min, or until the dye reaches the last 25% of the gel length (DNA travels from - to +).
- Place the gel under the camera, cover, turn UV on and take photos!
Preparing the ladder:
- get 1kb ladder DNA from the freezer (500 µg/ml).
- for 30 charges, 30 µl per charge, we need 900 µl:
- 60 µl of 1kb ladder DNA
- 150 µl of dye (6x loading buffer)
- 690 µl of water
BM Lab
In this lab the gels are slightly different. The total volumes for the small, the medium and the large gel are respectively 60ml, 80ml and 90ml. As we use 0.5x TAE buffer instead of 1x, we can use higher voltages (170V seems to work fine). The gel should run 20-40 minutes, not more. As the gel is thinner, load less DNA (up to ~10ul).
A gel was run with the following PCR products:
- Lane 1: Ladder
- Lane 2: LovTAP from 07.08 PCR
- Lane 3: LovTAP from 08.08 PCR
- Lane 4: LovTAP from 08.08 PCR
- Lane 5: NFAT from BioBricking PCR
- Lane 6: SEAP from BioBricking PCR
- Lane 7: TNFR from BioBricking PCR
- Lane 8: Master Mix
- Lane 9: Ladder
- Gel picture
Unfortunately, there still seems to be a problem with some of the PCRs we run. The BioBricking PCRs didn't work. We seem to have one acceptable LovTAP, however.
LovTAP digestion
Protocol: Restriction site digestion
- Look for the best pair of restriction sites, ideally with similar digestion temperatures and times.
- NEBcutter for finding cutting enzymes.
- Double Digest Finder for the parameters.
- Calculate the amounts required of:
- DNA
- Buffer (usually from 10x to 1x)
- BSA, if needed (usually from 100x to 1x)
- Enzymes (depends on the amount of DNA)
- Water
- Get the recommended buffer (and BSA if needed) from the freezer and let defreeze.
- Mix all the ingredients, except DNA, in a tube.
- Note: Enzymes should stay no longer than a couple of minutes out of the freezer. Don't touch the bottom of the tubes! Don't vortex!
- Distribute the mix in as many tubes as DNA samples and add the DNA.
- Keep in the Thermomixer at the recommended temperature.
Sowmya's recommended amounts (50 µl total solution):
- 5 µl of 10x buffer
- 0.5 µl of 100x BSA
- 1 µl of each enzyme
- 5 µl of DNA
- 37.5 (up to 50 µl) of water.
Protocol based on what was done on July the 4th.
The LovTAP PCR product was digested with the enzymes that would allow its ligation into pMP. LovTap digested with SpeI and NotI. Usual protocol. Incubation started at 16:20 and finished at 18:20. The product was then stored.
Ligation of SEAP and GFP into pGL
Protocol: Ligation
Ligation is a method of combining several DNA fragments into a single plasmid. This is often the
step following a PCR (and a PCR cleanup) or a gel extraction. You can also do a "dirty" ligation, where you follow a certain number of digestions directly by a ligation.
- Download the following spreadsheet : File:Team-EPF-Lausanne Ligation.xls
- Fill in the pink areas with the vector and fragment concentration, their size and the ratio.
- Add all the suggested ingredients order in a microcentrifuge tube, in the order they appear.
- Ligate for 2 hours at 14ºC.
- Immediately transform competent bacteria with the ligation product.
Note: This protocol hasn't been optimized for blunt-end ligation (though it might still work).
We ran a new ligation using the old digested PCR products for SEAP and GFP, as well as the digested pGL4.30 backbone. The folowing tubes were made (we didn't have enough backbone to try all of the possible ratios for GFP, unfortunately):
- SEAP1 into pGL4.30 (HindIII/MfeI) 1:2, 1:3, 1:4
- SEAP2 into pGL4.30 (HindIII/MfeI) 1:2, 1:3, 1:4
- nothing into pGL4.30 (HindIII/MfeI) 1:3 CONTROL
- GFP1 into pGL4.30 (HindIII/FseI) 1:3, 1:4
- GFP2 into pGL4.30 (HindIII/FseI) 1:4
- nothing into pGL4.30 (HindIII/FseI) 1:3 CONTROL
Total: 11 tubes. Incubated from 17.20 to 19.20.
Transformation with the ligations
Protocol: E.Coli Transformation
- Thaw the competent E.coli (DH5alpha) cells on ice (not in hands!)
- As soon as it is thawed, add 50µl of the cells to the DNA (~50-100 ng of pure plasmid, or some 2 µl usually)
- Let it rest on ice for 20-30 min. Meanwhile, put agar plate (with correct antibiotic) at 37°C for prewarming.
- Put the tube with DNA+E.coli at 42°C for 45 sec - 1 min (heat shock)
- Add 400 µl of LB broth and place at 37°C for 20-30 min (shaking)
- Spread the cells on the prewarmed plate (and let it dry)
- Incubate the plate upside-down at 37°C for ~14-15 hours (leaving it more than 16h decreases the plasmid quality)
11 bacteria plates were transformed with the ligation mixes. They were put at 37°C at 21.20.
Overnight culture of TNFR ligations
Protocol: Prepare Plasmid Extraction (culture for Miniprep)
- Select and number colonies on the plates.
- Prepare tubes of LB medium with the correct quantity of antibiotics (100 µg/ml for Amp, Spc or chloramphenicol).
- Amp can be found in the -20ºC freezer at Ecoli, labeled as "stock". It is 100 µg/µl, or 1000x.
- The tubes to be used are the 14 ml round bottom found in front of the iGEM drawers (Falcon). Culture with cap in the first step (loose) and close to the second step after culture.
- Touch each colony with a clean pipette tip and put it in a tube.
- Put in incubator.
13 Falcon tubes with different versions of the TNFR ligations were cultured for miniprep. They were put in the shaker at 37°C at 22.10.
