After solidifying my project plan last week, I started working on executing that plan this week, but not without a few unforeseen obstacles. The first step in designing the Rock probe which I hope to inject into sea star oocytes is to use PCR (polymerase chain reaction) to amplify the predicted Rock sequence from the sea urchin genome. Unfortunately, this step has been unsuccessful so far; after trying a handful of different primers (short DNA sequences that initiate replication). However, not all is lost – I am continuing to adjust variables and troubleshoot the process in hopes that the Rock sequence will appear. The second unforeseen obstacle this week was the uncooperative nature of some of the sea star oocytes I injected. On Monday, I injected fresh sea star oocytes with several different probes (mostly for practice, but also to get a hands-on sense of the wave phenomenon caused by different probes). Although one of the probes did not produce the expected waves, the other, an Ect2 mutant called ‘snowflake’, did cooperate (see kymograph and movie). It exhibited constant expression prior to first meiosis, waves during first meiosis, another period of constant expression prior to second meiosis, and more waves during second meiosis. These waves could be seen by following the fluorescently tagged Ect2. Left: Kymograph of ‘snowflake’ Ect2 wave activity. This kymograph was generated from time lapse movies of wave fronts traveling across the surface of the cell; the top of this image represents the surface preceding first meiosis, and as you look further down the image you can follow the wave fronts during first and second meiosis.
Another surprise I encountered this week came through the mail. Along with the expected ripe sea stars arriving to aid my faulty oocyte problem, the package contained sea slugs! The sea slugs were on their way to a medical center in New York, and are often used for research involving learning and memory due to their large neurons and relatively simple body plan. For now, we have no such lofty goals for the sea slugs, but have been amazed by their ability to produce enormous amounts of eggs – they lay impressive ribbons of thousands of eggs, which have been collecting on the sides of the tank. A few members of our nudibranch family. Top left: Charlemagne, top right: Chance, bottom left: Chuck, bottom right: no name yet, but open to suggestions!
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AuthorI am a rising junior at Carleton College, majoring in biology with minors in Neuroscience and Russian. I'm very excited to be working in Dr. George von Dassow's lab this summer, where I will be studying cell biology and embryology of marine invertebrates. Archives
August 2019
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