1. Resuspend colonies.

2. Prepare masterplate.

3. Prepare a PCR master mix (always prepare at least 10 % more).

4. Mix gently, avoid bubbles.

5. Aliquote the 22.0 μl of PCR master mix into each PCR tube.

6. Pick colony and put the toothpick or tip one into the Masterplate and then in the PCR tube/mix.

7. Do not forget the negative control!

8. Close tube.

9. Perform the PCR using Thermocycler as follow:

10. Store probes for short time on ice, for long at -20 °C.

11. Load probes on the agarose gel e.g. 10 μl (so in case you have enough left for another round).

B. Step by step for yeast:

1. If resuspended colonies are to be used: pipette 50 μl of a 0.02 M NaOH solution into each of a set of appropriately labelled PCR tubes or wells of a PCR plate. Using sterile pipette tips or toothpicks, transfer transformants to individual tubes/wells. The amount of cells resuspended must just be visible. Resuspend cells by pipetting or vortexing and incubate for ≥ 5 min at 37 °C.
2. If overnight cultures are to be used: pipette 40 μl of a 0.01 M NaOH solution into each of a set of appropriately labelled PCR tubes or wells of a PCR plate. Transfer 10 μl of each overnight culture to be tested to the appropriate tube/well and mix by pipetting up and down. Incubate for ≥ 5 min at 37 °C.
3. Prepare a PCR master mix (always prepare at least 10 % more).
4. Aliquot 22.5 μl of PCR master mix into each PCR tube.
5. Add 2.5 μl of the resuspended colony or overnight culture mixed with NaOH to the appropriate PCR tube.
6. Close the tubes
7. Perform the PCR using the following cycling profile:

8. Load probes on the agarose gel.

9. Store probes for short time on ice, for long at -20°C.

1. Pouring a Standard 1% Agarose Gel:

1. Measure 1g agarose and and mix it with 100 ml of TBE in a microwaveable flask.
Note: Agarose gels are commonly used in concentrations of 0.7 % to 2 % depending on the size of bands needed to be separated - Simply adjust the mass of agarose in a given volume to make gels of other agarose concentrations (e.g., 2 g of agarose in 100 mL of TAE will make a 2 % gel).
2. Microwave for 1-3 min until the agarose is completely dissolved (but do not overboil the solution, as some of the buffer will evaporate and thus alter the final percentage of agarose in the gel. Many people prefer to microwave in pulses, swirling the flask occasionally as the solution heats up.).
Note: gloves and glasses ! Caution HOT! Be careful stirring, eruptive boiling can occur.
It is a good idea to microwave for 30-45 sec, stop and swirl, and then continue towards a boil. Keep an eye on it as the initial boil has a tendency to boil over. Placing saran wrap over the top of the flask can help with this, but is not necessary if you pay close attention.

1. Let agarose solution cool down to about 50 °C (about when you can comfortably keep your hand on the flask), about 5 mins.
Note: Or cool down in water bath about 30 min.
2. Add ethidium bromide (EtBr) to a final concentration of approximately 0.2-0.5 μg/mL (usually about 2-3 μl of lab stock solution per 100 mL gel). EtBr binds to the DNA and allows you to visualize the DNA under ultraviolet (UV) light.
Note: Caution EtBr is a known mutagen. Wear a lab coat, eye protection and gloves when working with this chemical. If you add EtBr to your gel, you will also want to add it to the running buffer when you run the gel.
3. Pour the agarose into a gel tray with the well comb in place.
Note: Think about witch gel tray size you need (a small one or a big one).
Pour slowly to avoid bubbles which will disrupt the gel. Any bubbles can be pushed away from the well comb or towards the sides/edges of the gel with a pipette trip.
4. Let the newly poured gel sit at room temperature for 20-30 mins, until it has completely solidified.
if you are in a hurry the gel can also be set more quickly if you place the gel tray at 4 °C earlier so that it is already cold when the gel is poured into it.

1. Add loading buffer to each of your digest samples.
Note: Loading buffer serves two purposes: 1) it provides a visible dye that helps with gel loading and will also allows you to gauge how far the gel has run while you are running your gel; and 2) it contains a high percentage of glycerol, so it increases the density of your DNA sample causing it settle to the bottom of the gel well, instead of diffusing in the buffer.
2. Once solidified, place the agarose gel into the gel box (electrophoresis unit).
3. Fill gel box with 1xTAE (or TBE) until the gel is covered.
4. Carefully load a molecular weight ladder into the first lane of the gel.
Note: When loading the sample in the well, maintain positive pressure on the sample to prevent bubbles or buffer from entering the tip. Place the very top of the tip of the pipette into the buffer just above the well. Very slowly and steadily, push the sample out and watch as the sample fills the well. After all of the sample is unloaded, push the pipettor to the second stop and carefully raising the pipette straight out of the buffer.
5. Carefully load your samples into the additional wells of the gel.
6. Run the gel at 80-150 V until the dye line is approximately 75-80 % of the way down the gel.
Note: Black is negative, red is positive. (The DNA is negatively charged and will run towards the positive electrode.) Always Run to Red.
Note: A typical run time is about 1-1.5 hours, depending on the gel concentration and voltage.
7. Turn OFF power, disconnect the electrodes from the power source, and then carefully remove the gel from the gel box.
8. Using any device that has UV light, visualize your DNA fragments.
Note: When using UV light, protect your skin by wearing safety goggles or a face shield, gloves and a lab coat.
Note: If you will be purifying the DNA for later use, use long-wavelength UV and expose for as little time as possible to minimize damage to the DNA.
Note: The fragments of DNA are usually referred to as ‘bands’ due to their appearance on the gel.

Using the DNA ladder in the first lane as a guide (the manufacturer's instruction will tell you the size of each band), you can interpret the bands that you get in your sample lanes to determine if the resulting DNA bands that you see are as expected or not. For more details on doing diagnostic digests and how to interpret them please see the Diagnostic Digest page.

If you are conducting certain procedures, such as molecular cloning, you will need to purify the DNA away from the agarose gel. For instructions on how to do this, visit the Gel Purification page.