Katie, Entry #1: Great Times with MRSA!

My first two weeks at the Cheung Lab were great!  My first day started with a lab meeting where I got to meet everyone in my lab and learn about their research.  My lab has 6 members: my PI, 3 post docs, and 2 graduate students.  I am primarily working with Dhana, one of the post docs. 

During my first week, I learned more about my experiment and the techniques that I would be using.  I am looking for genes necessary for cold shock response in S. aureus. I am working with mutant S. aureus strains that have one gene that is interrupted by a transposon, inhibiting the function of that gene.  To determine whether we would conduct the experiment by growing the mutant strains in solid or liquid media, I grew the strains in both and monitored the growth.  I grew mutant and wild type strains on agar plates at different temperatures and checked their growth daily.  I also grew the strains in liquid media and took the optical density, the measurement of light absorbed by an object, using a spectrophotometer to measure the growth of the bacteria cultures (as cells divide and replicate, the optical density increases).  I measured the optical density until the cultures reached the stationary phase of growth and made a growth curve using the measurements. I did this for a few days to make sure that I got accurate results. I also helped another post doc with his research by randomly picking colonies of S. aureus, which he will later analyze. 

The spectrophotometer

Over the weekend, Dhana and I went to a nearby hot air balloon festival and while I did not get to see any of the hot air balloons take off (bad weather), I got to see the beautiful Quechee Gorge.   

The Quechee Gorge

During my second week at the lab, I grew1,920 mutant S. aureus strains on agar plates at different temperatures, observed which strains had difficulty or could not grow in cold conditions, and made a log of those strains and the genes that were interrupted by transposons in each strain.  Next, I began growing some of these potentially cold-sensitive strains at different temperatures in liquid media, observing their growth using the spectrophotometer, and making more growth curves.  I also helped Dhana with some of her other research by preparing and loading gels for gel electrophoresis.  At the end of the week, I went to a barbeque at my PI’s house and had a lot of fun!

My desk/lab bench

Overall, I am enjoying my lab and am excited to learn more in the upcoming weeks.