Hi, You can try this:

Make gel as usual in 1x TAE/TBE buffer and cool down. Add about 30µl of the 2 mg/ml Crystal Violet solution to the agarose (~100ml) and swirl to mix, then pour the gel as usual. Add 10x Crystal Violet loading dye to the DNA sample and load onto the gel

Run the gel. Cut the fragment from the gel and proceed directly to gel purification.

Remember: If no band is visible, insufficient DNA was loaded (it's less sensitive than Ethidium bromide: 200 ng is the minimum DNA amount visible)

Crystal violet solution:

2 mg/ml crystal violet in 1x TAE/TBE

10x Crystal violet DNA loading buffer

normal 10x loading buffer recipe containing some of the crystal violet solution instead of Bromophenol blue and Xylene cyanol (I prepare 5X loading buffer adding V/V Crystal violet solution)

Hope it helps ;)

By the way, DON'T use TBE when it's for isolation of a fragment for mircoinjection. Use TAE.

Thank you both! It works, but the amount of DNA should be bigger then 1ug /lane.