Team:UC Davis/Protocols
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Protocols
LB Media
Antibiotic Stock Solutions
Materials
ChloramphenicolHeat Shock Transformation
Procedure
- Preheat water bath to 42º C.
- Thaw competent cells on ice for 10 minutes.
- Use 50 µL competent cells, add transforming DNA [up to 25 ng per 50 µL of cells, volume not exceeding 2.5 µL (5%)]. For control add 1 µL of control DNA (PUC19 carb resistance). Swirl to mix, store on ice 5 minutes.
- Heat shock in 42º C water bath for 45 seconds.
- Cool cells in ice bath for a few minutes.
- Add 800 µL LB to each tube, set in shaker at 37º C for 45 minutes.
- Transfer 200 µL of culture per plate (containing the appropriate antibiotic).
- Spread using glass beads.
- Invert plates and incubate overnight (12-16 hrs) at 37º C.
Making Chemically Competent Cells
Procedure
- Prepare 0.5 M PIPES (pH 6.7) (piperazine-1,2-bis[2-ethanesulfonic acid]) by dissolving 15.1 g of PIPES in 80 ml of pure H2O (Milli-Q, or equivalent). Adjust the pH of the solution to 6.7 with 5 M KOH, and then add pure H2O to bring the final volume to 100 ml. Sterilize the solution by filtration through a disposable pre-rinsed Nalgene filter (0.45-µm pore size). Divide into aliquots and store frozen at -20°C. Prepare Inoue transformation buffer by dissolving all of the solutes listed below in 800 mL of pure H2O and then add 20 ml of 0.5 M PIPES (pH 6.7). Adjust the volume of the Inoue transformation buffer to 1 liter with pure H2O.
- Pick a single bacterial colony (2-3 mm in diameter) from a plate that has been incubated for 16-20 hours at 37°C. Transfer the colony into 25 ml of SOB medium (LB may be used instead) in a 250-ml flask. Incubate the culture for 6-8 hours at 37°C with vigorous shaking (250-300 rpm).
- At about 6 o'clock in the evening, use this starter culture to inoculate three 1-liter flasks, each containing 250 ml of SOB. The first flask receives 10 ml of starter culture, the second receives 4 ml, and the third receives 2 ml. Incubate all three flasks overnight at 18-22°C with moderate shaking.
- The following morning, read the OD600 of all three cultures. Continue to monitor the OD every 45 minutes.
- When the OD600 of one of the cultures reaches 0.55, transfer the culture vessel to an ice-water bath for 10 minutes. Discard the two other cultures.
- Harvest the cells by centrifugation at 2500g (3900 rpm in a Sorvall GSA rotor) for 10 minutes at 4°C.
- Pour off the medium and store the open centrifuge bottle on a stack of paper towels for 2 minutes. Use a vacuum aspirator to remove any drops of remaining medium adhering to walls of the centrifuge bottle or trapped in its neck.
- Resuspend the cells gently in 80 ml of ice-cold Inoue transformation buffer.
- Harvest the cells by centrifugation at 2500g (3900 rpm in a Sorvall GSA rotor) for 10 minutes at 4°C.
- Pour off the medium and store the open centrifuge tube on a stack of paper towels for 2 minutes. Use a vacuum aspirator to remove any drops of remaining medium adhering to the walls of the centrifuge tube or trapped in its neck.
- Resuspend the cells gently in 20 ml of ice-cold Inoue transformation buffer.
- Add 1.5 ml of DMSO. Mix the bacterial suspension by swirling and then store it in ice for 10 minutes.
- Working quickly, dispense aliquots of the suspensions into chilled, sterile microcentrifuge tubes. Immediately snap-freeze the competent cells by immersing the tightly closed tubes in a bath of liquid nitrogen. Store the tubes at -70°C until needed.
Reagent | Amount per liter | Final Concentration | |
---|---|---|---|
MnCl2•4H2O | 10.88 g | 55 mM | |
CaCl2•2H2O | 2.20 g | 15 mM | |
KCl | 18.65 g | 250 mM | |
PIPES (0.5 M, pH 6.7) | 20 ml | 10 mM |
Double Restriction (Fast) Digest
Materials
Procedure
Ligation
Materials
Ligation reaction:Vector control:
Insert control:
Procedure
Gel Electrophoresis
Procedure
- Add 0.5 grams of agarose to 50 mL of 1X TAE buffer.
- Microwave agarose/TAE until agarose completely dissolved.
- Cool under water, add SYBR safe dye (2.5-3µL).
- Pour into mold with appropriate comb.
- Wait 15 minutes for gel to solidify.
- Load DNA with dye into wells while submerged in 1X TAE.
- Run gel at a constant 120V.
- Check gel periodically.
Gel Extraction and Purification
Procedure
- Prepare agarose gel and use 3 combs to make a bigger well.
- Once it has run, use hand held UV lamp (in the dark, wearing goggles) to identify bands.
- Cut out desired band with stamp pipette tip and transfer to a clean tube. The stamp pipette tip can be left in the tube to be cleaned out with a smaller pipette tip.
- Weigh gel fragments and add 200 µL Buffer NTI for every 100 mg agarose gel. Incubate sample for 5-10 min at 50º C, vortexing every 2-3 min until the gel is completely dissolved.
- Load sample onto column over collection tube. Centrifuge for 30 sec at 11,000 x g.
- Discard flow-through and replace column on tube.
- Add 700 µL Buffer NT3 and centrifuge for 30 sec. at 11,000 x g. Discard flow-through.
- Centrifuge for 2 min at 11,000 x g to completely remove buffer.
- Transfer column to a 1.5 mL tube and add 20 µL ddH2O.
- Incubate at room temperature for 10 min.
- Centrifuge for 1 min at 11,000 x g.
PCR Amplification for Golden Gate Assembly
Materials
Golden Gate Assembly
Materials
DNA Extraction (Minipreps)
Procedure
- Sediment the cells by centrifuging 1-5 mL of overnight LB-culture. Remove all medium.
- Add 250 µL Resuspension Buffer (R3) with RNase A to the cell pellet and resuspend the pellet until it is homogeneous.
- Add 250 µL Lysis Buffer (L7). Mix gently by inverting the capped tube five time. Do not vortex. Incubate the tube at room temperature for 5 minutes.
- Add 350 µL Precipitation Buffer (N4). Mix immediately, or for large pellets, vigorously shaking the tube until the mixture is homogeneous. Do not vortex. Centrifuge the lysate at >12,000 x g for 10 minutes.
- Load the supernatant from the prior step on a spin column in a 2-mL wash tube. Centrifuge at the column for 12,000 x g for 1 minute. Discard the flow-through and place the column back into the wash tube.
- Add 700 µL Wash Buffer (W9) with ethanol to the column. Centrifuge the column at 12,000 x g for 1 minute. Discard the flow-through and place the column into the wash tube. Centrifuge the column at 12,000 x g for 1 minute. Discard the wash tube with the flow-through.
- Place the spin column in a clean 1.5 mL recovery tube. Add 30 µL of ddH2O to the center of the column. Incubate the column for 10 minutes at room temperature.
- Centrifuge the column at 12,000 x g for 2 minutes. Discard the column. Store plasmid DNA at 4º C (short-term) or store the DNA in aliquots at -20º C (long-term).
Making and Reviving Glycerol Stocks
Procedure
Sequencing Preparation
Procedure
Measuring DNA Concentration
Procedure
- Log in to nanodrop program.
- Moisten a Kim wipe and clean the pedestal.
- Apply 2 µL H2O to pedestal and click 'OK'.
- Press 'Blank' button.
- Wipe blank from pedestal using Kimwipe.
- Apply 2 µL of desired sample to pedestal.
- Click 'Measure'.
- Print results.
Tecan Testing
Procedure
- Grow cultures overnight in LB at 37 C, 150 RPM.
- Measure OD600 and dilute to get <0.01 OD600.
- Grow until the OD600 approaches 0.5.
- Load 96 well plate with LB, appropriate antibiotic, inducer stock solutions, and the appropriate volume of culture so as to reach an OD600 of 0.1 in 200 µL.
- Run Tecan program.
Primer Design for Site-Directed Mutagenesis PCR
Procedure
- Identify site that needs to be mutated.
- Check the amino acid sequence to create a silent mutation, generally the last base in a codon.
- Check a codon usage table to help choose how the codon should be changed, try to pick a frequently used codon.
- Take about 20 base pairs upstream and 20 base pairs downstream of your desired mutation site to create your primer, try to have it start and end in a G or C. The sequence should be identical to the template except for the one changed base you are trying to mutate at the center.
- The reverse primer will be the reverse complement of this sequence.
Site-Directed Mutagenesis PCR
Materials
PCR program
- 95º C 1 min
- 95º C 50 sec
- 60º C 50 sec Repeat Steps 2-4 17x (18x total)
- 68º C 1 min / kb of plasmid
- 68º C 7 min
- 4º C Hold
Electroporation Transformation
Procedure
- Thaw electrocompetent cells on ice, keep on ice when thawed.
- Aliquot 20-30µL of competent cells into separate 1.5mL microcentrifuge tubes on ice.
- Pipette appropriate amount of DNA (1 µL) into tube on ice.
- Transfer cell/DNA into prechilled electroporation cuvette, keep on ice for 1 minute.
- Make sure the electroporator is set to:
- Time constant = 4.5-5.0 ms
- Resistance = 200 W
- Capacitance = 25 mFD
- Volts = 1.7 kV (for 1mm gap cuvettes)
- Electrocute cells once.
- Add 1mL of LB to cuvette, pipette up and down to mix, and transfer mixture to 14mL Falcon culture tube.
- Incubate for 1hr at 37C shaking at 150rpm.
- Plate cells on appropriate antibiotic.