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CHO cells transfected with LovTAP only
Protocol: Transfection of CHO cells
This is the transfection protocol used at the LBTC lab for CHO DG44 cells. The transfection reagent is PEI (polyethylenimine).
Please use the provided Excel sheet to calculate the volume of plasmid you should add to the cells. Replace every value in red by your own, then print the sheet out and follow the provided protocol.
1. Passage seed 1 day prior to transfection.
2. Prepare tubes (yellow caps with holes) by addition of the calculated amount of DNA.
3. Centrifuge the necessary volume of seed (after a PCV measurement), remove conditioned medium with the pump (use a 2 ml serological pipet with a broken neck) and resuspend (first in 10 ml) in necessary volume of fresh medium to achieve the required cell density (3 mio/ml).
4. Add 5 mL of the cell suspension to the tube with DNA and mix orbitally.
5. Add the PEI (45 µl) to the Cell+DNA mixture as soon as possible, flick 3 times.
6. Place in the incubator at 37°C.
Tubes 1 and 2 were transfected with 100% LovTAP (we hoped to detect its intrinsic fluorescence on the Guava). Tube 3 was 95% LovTAP and had 5% of pOri-GFP as a transfection control.
Digestion of pSB1C3-RFP and linearized pSB1C3
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.
Three different digestions of the pSB1C3 backbone (for inserting 3 different PCR products).
- Linearized pSB1C3 (linearized backbone from the tubes delivered with the iGEM kit) with NotI
- pSB1C3-RFP from the plates received from the iGEM Headquarters with EcoRI and SpeI
- pSB1C3-RFP with XbaI and PstI
Gel Extraction of pSB1C3
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).
- Lane 1: Linearized backbone digested with NotI
- Lane 2: RFP plasmid digested with EcoRI and SpeI
- Lane 3: RFP plasmid digested with XbaI and PstI
Picture of the gel:
Maxiprep
Protocol: MaxiPrep
The evening before, take a big Erlenmeyer (at least 1L) and put 200ml LB in it. Add the appropriate antibiotics at the correct concentration (ampicilin: 200ul of 100mg/ml solution). Put in bacteria from a single colony of a freshly streaked plate or from a glycerol stock (warning: taking bacteria from glycerol stock seems to cause them to start growing later - due to thawing? - add one-two hours to the incubation time). Put them in the incubator for 14-15 hours (the contents of the bottle should be yellow-ish between translucid and opaque).
We then use the MaxiPrep kit (Plasmid DNA Purification kit) and protocol from Macherey-Nagel.
The complete handbook can be found here. We usually use the protocol that starts at page 24 for "Maxi".
Started an overnight Maxiprep culture of the pCEP4-HA-RO plasmid to start LovTAP experiments!
