20.109(S08): old announcements

• Diagnostic digest results have been posted on the Day 6 "talk" page (02.29.08).

• A bit more Methods info (02.29.08):
  • Gels were stained with ethidium bromide at a final concentration of 0.2 μg/mL.
  • The E. coli cells for transformation were XL1-Blue cells from Stratagene.
  • The ligase used was originally at 400,000 U/mL.

• A few pieces of information that may be useful for your Methods (posted 02.20.08):
  • Gels this year were made in 1X TAE buffer, which contains 40 mM Tris (pH 8), 20 mM acetic acid, and 1 mM EDTA.
  • The Qiagen kits you used are called the QIAquick PCR Purification Kit and the QIAquick Gel Extraction Kit. You may say that you used them according to the manufacturer’s instructions rather than describing the protocols step-by-step. However, you can briefly mention the principle components if you want (e.g., “DNA was purified on silica gel columns using the… kit and eluted in … buffer”).
  • Your original digests (Day 2) contained ~ 5 μg of backbone. If you don’t know the amount or concentration of something (e.g., your PCR products), it’s fine to mention a volume instead in this case. Otherwise a final amount or concentration is generally preferred.
  • Enzyme amounts are often given in terms of activity units, U. The XbaI and EcoRI enzyme stock solutions that you used are both at 20,000 U/mL.