Monday, March 4, 2013

Week #6 (2/17-2/23/13):

Wow! Finally caught up! I guess this is what happens when you do not want to post garbage on the internet for numerous people to scoff at (Note: If you already think poorly of this blog then this following post and any posts hereafter are invalid. You should shut off your browser right now and go read a book). Nonetheless, I know even experienced bloggers that fall behind. Take thee PZ Myers for instance. I doubt he is ashamed to say he needs to catch up once in a while. This being said, he needs to post a summary of what he taught in class on Wednesday the 20th! It is always a good refresher to read a summary of the classroom teachings and discussion, but when I miss class just one day... Oh boy. What do I get to read? Nuffin.

Now, I was actually going to take this time to talk about the goings on in our Dev bio lab. Myself and other students were to cut up worms for nematode cultures last Monday. It was not the most pleasant experience, but anything for science! After clearing out the drawer of last year's worms (delightful!) and storing our petri dishes, we were free to go for the week, aside from the occasional visit to check up on the cultures. In fact, being the good student I am, I stopped by three days later to check up on them. The image below is how they looked after three days. The sight of them was more pleasant than the smell, trust me! Hopefully, they are in good shape for tomorrow's analysis.

We are studying these creatures because their developmental stages are precisely worked out (plus they are free). In fact, our study of nematodes in lab parallels that of lecture. In class, we talked about the development of the vulva in the nematode.  It is an excellent example of induction of cellular fates and similar mechanisms that drive the differentiation of a multicellular organism. This example is well known because it has very a specific pattern of development. We know exactly where all these cells came in the final product.

The source of this induction effect is the anchor cell of the nematode. It is a source of an graded inductive signal which initiates the differentiation of adjacent cells. The specific induction pathway include many genes that encode common proteins such a EGF which is found all over the animal kingdom and ras/raf which mediate growth and differentiation. Ras/raf are involved in human cancer as well.

Nematodes can be both dioecious (meaning there are two separate male and female individuals) and hermaphroditic which means that the worm can self fertilize its eggs. After establishing the mechanism for the development of the vulva we talked about a phenotype that can be detrimental to the survival of the parent worm and that is the bag of worms phenotype. It is the vulva-less phenotype and typically eggs will be self-fertilized, hatch internally, and eat the mother! Not a desirable trait to any extent.

The next week or so we will be  focusing on the examination of the nematodes and after that: flies!

So that is it. Auf Wiedersehen!

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