This Is How We Do It ♫

Julianna Duran, Virginia Tech

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First and foremost, if you didn’t get the reference in the title please click here!

Now that I have educated you on the topic of music, let’s switch to science.

 The Approach: In my previous post I mentioned that I am studying the lipids of Nile Crocodile and Mozambique Tilapia. So the first thing I did is wrestle the reptile like Steve Irwin and hand catch my fish – just kidding, but imagine how cool that would be! My samples were collected from Lake Loskop, South Africa in 2014. Once they were in my possession, here is what I did.

  1. Sample Preparation
    • The muscle tissue samples I received looked like chicken breasts you buy from the grocery store – except the size of a fat bean. These solid chunks need to be turned into a fine powder for me to analyze them. This was done by freezing the sample in the cryomill machine – where the samples were shaken extremely fast and broken up

      Cryomill

      Cryomill

  2. Extraction
    • Think of what happens when you pour oil in water. They go to different ends and don’t mix, right? (Yes) That is exactly what I’m doing with my samples. We are adding lots of chemicals to break down fats into their building blocks: Fatty Acids! The muscle layer (organic layer) hates touching the chemicals, so I take that out and can use it for my next step!
    • Check out a video I made of one of my extractions
  3. Gas Chromatography
    • This instrument is how I will measure the amount of each fatty acid in my samples.
    • How does it work?
      • The sample is injected into the system and enters a narrow glass column. The sample separates in this column based on its weight and boiling point. The particle encounters a flame at the end of the glass, which detects what specific fatty acid it is. The computer then gets this signal and generates a graph showing a fatty acid profile. Each peak on the graph is a different fatty acid, and the height of the peak indicates how much of it there is in the sample.
      • For help envisioning this process, take a look at this video (I used it when I learned about this instrument!)

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        Chromatogram

Summary:

I will be physically and chemically breaking down my samples, then getting fatty acid profiles for each of my individual species. This is all to see if there is a difference between healthy and diseased species and what lipids are most affected by Pansteatitis!


Supported by the Fort Johnson REU Program (NSF DBI-1757899), Dr. Mike Napolitano, Dr. John Bowden, The College of Charleston, NOAA, and NIST. 


References:

CryoMill. https://www.retsch.com/products/milling/ball-mills/mixer-mill-cryomill/function-features/ (accessed Jun 18, 2019).

Gracilaria: What are you hiding?

Nick Partington, St. Olaf College

Screen Shot 2018-07-03 at 10.37.44 AMThe approach: In my previous post, I discussed how we will primarily be researching differences in abundance and diversity of fish and fish species that utilize Gracilaria vermiculophylla as habitat in the Charleston harbor. In order to do so, we have been collecting several samples of fish from the two habitat types this summer. We then sort and identify fish from each sample to determine the number of individuals per species found in each habitat type, and will later carry out statistical analyses to determine if any significant differences exist between the two habitat types. Each of these steps, from collecting to identifying to analyzing, consists of techniques that must be replicated for each sample in order to ensure consistency.

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Sampling in a “sparse” patch of G. vermiculophylla

The first step is to collect the samples. We do this at Grice Cove, just a few minutes’ walk from Grice Marine Lab. On site, we have identified a section where about 20% or less of the beach is covered by G. vermiculophylla. These are the “sparse” patches. The “dense” patches are further down the beach, where about 80% or more of the beach is covered by the algae. At each site, we pull a fifteen foot seine net through about 1-2 feet of water for a distance of 15 meters. We then sort through the net, saving all of the fish and discarding plant matter and invertebrates such as crabs and shrimp. The next step is to sort and identify the specimens that we collected.

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An early stage of sample sorting. This sample includes a flounder (upper right), pipefish (upper left), and several anchovies (middle).

 

 

After being fixed in preservatives for about a week, we sort through our samples, grouping identical fish and identifying specimens to the lowest classification possible (hopefully to the species level). After the sorting and identifications are complete, the numbers of fish of each species for each sample are recorded. Later, after we have collected all of our data, we will perform statistical analyses on the data to discern any significant differences in diversity and abundance of fish that might exist between dense and sparse patches of G. vermiculophylla. Stay tuned to hear about our findings!


Special thanks to Dr. Tony Harold for his guidance in this research project. This project is funded by the National Science Foundation and is supported by the Fort Johnson REU Program, NSF DBI-1757899.