Design of Yeast Genomic Expression Experiments

RNA _{t > 0}/ RNA _{t = 0}

II. Execution of the experiment

A. Before beginning sample collection, allow the subculture to recover from stationary

phase

1. At least 2 doublings (not absolute time)

B. Begin the experiment at a cell density that will avoid diauxic shift at end of the

experiment

1. Aware that timing of diauxic shift is condition-specific (media, temperature,

aeration, environmental stress)

2. For long experiments use a chemostat to maintain culture conditions

C. Record ALL possible details – you’ll be glad you did

1. Examples:

a. OD₆₀₀, cell number, cell volume over time

b. Cell viability through experiment

c. Cell morphology: take periodic photographs of the cells to

characterize cell shape, cell cycle arrest

d. Nutrient concentrations (glucose, NH₄, ethanol, etc.): Always freeze a

small aliquot of the culture media to measure such things later

e. If possible, measure drug concentrations in the culture during

experiment

2. Record any anomalies

3. Record anything you can think of … you many not know what details

will be valuable until After you see the results