Sunday, July 14, 2013

Leeah: Week 3

Week 3
On Monday, Terra showed me the second to the last step to the DNA extraction/purification process. took the tissue samples from last week’s extraction on July 6th and purified them in order to be shipped to a company that will sequence them for us. This is very similar to the way that DNA is extracted from very large tissue samples as opposed to a larval extraction. We use a column method that includes a filter fitted into a small tube and we wash the DNA using various buffers. In extracting DNA from tissue samples we wash it several times which causes some of the DNA to be lost in the process. During the purification process we only do the wash once as there is such a small amount of DNA left by that time.
On Wednesday I went about in the purification of four larval samples. I forgot one crucial step in this process, centrifuging the samples one last time to get the rest of the buffer containing ethanol out. Fortunately we were able to save these samples and go through a double purification process. Some DNA was lost; however, in the package sent to the sequencing company we were able to include a greater volume of the samples that had dimmer bands. One pleasant surprise on Wednesday occurred during our plankton tow. There were several Recurvatum Pilidium captured in our net. These are the “sock-shaped” larvae with a trunk. I managed to catch my first one and four more thereafter. On Thursday we went to Middle Cove and collected several adult worms in the intertidal zones. This was far more difficult than digging in the mudflats as we had to turn over rocks and not disturb the eel grass beds.
            Here are some of the Recurvatum that I captured this week:

Note that in the second picture this Recurvatum is displaying what is presumably a feeding posture. These kinds of pilidia will sometimes float in the water with their trunk extended, showing off their unusual cirri. These pilidia also swim much like a bullet, in a spiraling motion with the trunk pointed down.
Friday was a day of clean up in the morning. I froze down several of the larvae so that I wouldn’t have to take care of so many of them. I spent my afternoon working on ink drawings of some worms that caught my eye, as the small Micura I drew on the first week looked rather lonely. Included is Micura cerebrosa or the “pink-brained” nemertean that is part of the Micura species complex we are studying, Micura alaskensis also part of the complex, Micura verilli the striped and spotted nemertean with a bright orange head and that sports a lovely shade of red-violet and finally the very large and very uncooperative Micura wilsoni. While taking tissue samples of this nemertean, Terra discovered that we had a ripe male and female among our adults and she fertilized a large sum of eggs. This is very exciting news as we have never seen the larvae of Micura wilsoni before.

  Finally on Saturday I was part of a group to go retrieve a striped dolphin that had washed up on the beach and perished the day before. I did not get much time to draw it but I managed to crank out four sketches. I hope to attend the day of the dissection. I would like to do very in detail and realistic drawings of the dissecting process for reference.

Until that day and until I get my hands on a camera these are the sketches I did on Saturday:


  1. Your sketches of the ribbon worms are just beautiful. Thanks for sharing them and your experience.

  2. Thank you for this extremely brilliant blog the DNA extraction/purification process! We really appreciate your blog post. There are actually a multitude of techniques we could put in to make really a good use of information without much efforts and financial resources. Thank you so much for giving light to many problems we haven’t come across before using your blog.
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    1. Thanks for showing an interest in this project.

  3. Leeah,
    Thanks for helping collect the dolphin. The birds and mammals students will benefit greatly from this really fresh specimen later this term. We will be dissecting the dolphin on Tuesday Aug 6.

    1. I cannot wait to attend the dissection. I will have a camera and my sketch book ready :)