Fertilization is defined as the fusion of gametes, in humans known as an egg and sperm. This fusion produces a zygote that will develop over time into an organism. When a zygote develops, it goes through a number of divisions, otherwise known as cleavages, so it can become that organism. The organism begins at a one cell stage and cleaves until a whole organism is formed. After each cleavage, more cells are distinguishable; each cell is now called a blastomere. After waiting until the third cleavage, which is when there is a horizontal division between the four previously produced cells, another four cells are produced. These four cells are a grouped into two pairs each consisting of two cells. Each pair will move to the opposite sides of the zygote. The bottom pair is located at the vegetal pole. This pair will divide further into macromeres and micromeres. Now at this stage, the larvae are at the 16 cell stage.
Previously discovered, micromeres are responsible for the development of the larval skeleton. The experiment we focused on this week was ablating sea urchin larvae’s micromeres to see whether their development affects how they retain the algae they eat, Rhodomonas. We believe that there is an effect(or correlation) between the mouth’s size and the frequency of keeping such jumpy prey in their mouths. What we did was fertilize sea urchin eggs and wait until they had reached their 16-cell stage. Once the larvae reached this stage we ablated their micromeres away. We recovered those larvae and will now observe their reactions to this phenomenon.
The slideshows underneath show the current stage of our original cultures from week 1. The order goes from left to right: Sand Dollars(leftmost), Sea Urchins(), and lastly the Starfish().
On to our previous weekend, the REU interns went camping at Cape Arago. There we had the chance to meet the other interns at the main University of Oregon campus. Personally, I had only camped once before this excursion, so I was ecstatic to do it again. I am so surprised and happy with my camping experience. The campsite was clean and the people seemed friendly.The weather was so nice and warm perfect for a day at the beach, so we set up camp and walked over. After half an hour, some REU interns and I decided to go on a hike. The best points of our hike were the overlooking and astonishing views of the beach, watching harbor seals jump into the ocean and seeing the historical site, which contained a rose garden and greenhouse. Once we got back down we started to have dinner and ended that meal with a campfire smores and attempted scary stories. It was exactly how I pictured camping the only thing that exceeded my expectations was the amount of fun I had!
Fast forward to the 4th of July, we had the day off . We all enjoyed some extra sleep time and met up with each other at the picnic. There we had great food and great company. After lunch, we did an egg toss. It was my first time participating in this activity so I will explain what it is. You and a partner stand across from each other and you toss an egg. After each throw, both partners take a step back and the game keeps going until all the eggs have cracked. My partner was Nancy, although we lost it still was loads of fun. We were both pleasantly surprised that we had made it so far in the game.
Hardin, Jeff. Figure 3.1-3.15 “ Characteristic stages during early development in Lytechinus variegatus.” Chapter 3, The sea urchin embryo in “Embryos: Color Atlas of Development” (J.Bard,ed.) London, Wolfe Publishing embryoworms.zoology.wisc.edu/publications/publications.html#research_urchins
SeaUrchin Clipart Image #16. Digital Image. Clipground. http://clipground.com/sea-urchin-clipart.html
Hi! My name is Kostantina Orselli and I am transferring to California State University of Northridge. My interests include hiking, kayaking, playing with my dog, hanging out with friends, watching movies and more. I am ecstatic to be experiencing this opportunity at OIMB!