Brown: Team Resistance/26 June 2008

26 June 2008

Bacteria Mystery Solved!

Used spec in Tatar Lab (5th floor BioMed) and obtained reading of original culture, 1/10 dilution, 1/100 dilution and obtained readings that were expected.

• Original culture: 1.17 (expected, out of range of spec)
• 1/10 dilution: 0.401
• 1/100 dilution: 0.047

These are expected from a regular spec. (UV/vis) so from a nanodrop (1mm area instead of 1cm) readings a degree less than 10 would be expected

• Our current readings have been correct
• With the nanodrop, stationary phase is >0.1 and so logarithmic phase is >0.01.

Labview has been giving us problems

• Reading continuously decreases
• Output voltage won’t equal the voltage we set (won’t go past 5V)

Daniel Ludwig suggests:

• Try putting a for loop around voltage reading but inside while loop to make an alternating voltage (Daniel)
• Try using different resistors (smaller than 1Mohm) because our readings have been around 100 or 200kohms so a smaller resistor would give more accurate readings (John S. let us borrow his resistor kit)

Plan for the day: Test if our bacteria work:

• Add arabinose to pVJ4 culture and see if resistance changes with multimeter
• Talk to Daniel (and hopefully Jerry Daniels) to try and fix our apparatus
• Meeting with Jill Kreiler @3:00pm
• Make culture of pVJ4 tonight from glycerol stock to miniprep tomorrow for sequencing

Tried running a freeze-thaw test with 10mL of our sample:

• Plate number 6 (with culture) gave a completely different reading than the two other plates with culture (300Mohm vs. 50-60Mohm
• Tried switching alligator clips→ reading completely changed (300Mohm→ 60Mohm)
• Conclusion: alternating voltage/current is necessary to prevent migration of ions
• Attempted implementing an alternating voltage with LabView but did not work→ will call Daniel Ludwig tomorrow for his help