Collaborative Research

Go with the Flow
by -- January 16th, 2013

Hey there!  My name is Catherine Henry, I’m a sophomore at Duke, and I am double majoring in biology with an ecology concentration and environmental science.  During the cruise, I am conducting research using flow cytometry to determine the population size of different phytoplankton, namely Prochlorococcus and Synechococcus.  Flow cytometry is a process which involves shooting lasers at cells in solution and collecting the scattered light.  The flow cytometer is a finicky machine since it’s very easy to have noise in your data (air bubbles or debris that you don’t actually want in your sample).  It requires a lot of cleaning and attention, but since it’s a half million dollar machine, I guess it’s worth it!

Running a sample involves quite a few steps.  First, you vortex, or shake up, the beads, which are little pieces of plastic which have a known emission frequency.  They serve as a guide when analyzing our data.

Carrie prepares the beads for pipeting.

After vortexing the beads, you measure out 10uL of beads and 450uL of your seawater into an Eppendorf tube and vortex to evenly mix the solutions.

10uL (microliters) of beads are pipeted.

450uL of seawater are pipeted.

A syringe is then filled with the solution, and all air bubbles are removed.  The syringe is placed into an apparatus which pushes the syringe at a constant velocity, giving an even flow of solution into the flow cytometer.

This machine ensures a constant velocity for the flow of solution.

The sample has to prime at a higher velocity for 1 minute (100uL/min), after which it runs at a lower velocity (10uL/min) for 10 minutes.  On the computer screen, you are able to see live data as it records information about the phytoplankton.

The graphs in the upper left-hand corner show the current profiles of the cells passing before the laser.

Once the sample is done, it’s great to get some support from the flow cytometer mascot…


Isn’t science fun?

Carrie Schmaus! Full-time scientist, part-time flow cytometry hand model.

So, now you know how to use a flow cytometer!  For my project, I’m using flow cytometry to measure changes in phytoplankton populations which are incubated at three different temperatures (one standard, and ones at both 2 degrees Celcius above and below).  This will simulate the direct effect of temperature on phytoplankton and will essentially be simulating the direct effect of global warming.

Check back at this blog to hear about how my research is going and the other experiments which are ongoing aboard the R/V Kilo Moana!

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