Lab #4: Primary Literature and Experimental Design
9/13/2018
By Marci Jordan
Bio 1105-31
Pre-Lab and Lecture
Learning Theory
Although we learned about learning theory last lab with fixed and growth mindsets we applied that to science. Through an article I learned how creativity powers science. Associative thinking is best when doing a relaxing activity and allows new great ideas. Along with the article a video was provided discussing the great discoveries that were made by using Tetrahymena. These discoveries were made by people who were thinking creatively and outside the box. Who ever would of thought these small, abundant, and cute cilliates could help with cancer research and even win two noble prizes! We also discussed in class lecture why ciliates are such good model organisms. Unlike mice or other model organisms, ciliates are cheap and reproduce quickly. Therefore an experiment that would take months is quickly advanced as results are available quicker by rapid reproduction. You can get 10 ciliate generation in a week while it would take months for other species. I would who discovered how beneficial ciliates are in a lab? How long have ciliates been chosen as a model organism? Are there any organisms that are better model organisms then ciliates?
Nature of Scientific Communication
In the pre-lab I was notified about the unique opportunity the Baylor Library offers. They often have “Science Workshops” that help students understand the process of scientific communication. This is valuable information as throughout school it will help students understand how to properly communicate and also what to look out for. Next as a scientist its important to know to evaluate scientific sources. This requires knowing where to look and what to look for. Usually primary or secondary scientific literature sources are the best choice. With a overwhelming amount of sources available on the infinite internet evaluating the validity of a source is necessary. Questions such as where source was published, was it peer reviewed, author, authors reputation, date, and type of source are good to decide if it is a good article.
Once sources are found you need to cite them in your paper. Helpful tools were listed in the pre-lab such as “Zotero” and “RefWorks” which are tools that collect, manage, and cite research sources. This is critical as most professors will deduct heavily or fail a paper if it does not have the correct citation. With improper citation comes plagiarism, either on purpose or accident but its all the same, and is against the honor code. In addition to OneSearch, Baylor also offers a database called “PubMed” which can find articles with keywords. I wonder what most Baylor students perfer, OneSearch or PubMed? I wonder if one is better for different purposes? I wonder which one has more articles about Tetrahymena?
Basics of Tetrahymena
As stated before Tetrahymena are great model organisms for experiments. They have been used many times for biochemistry and cell functions. But Tetrahymena have been used extensively in research of studying the cytoskeleton and sub-cellular components. I stated above that Tetrahymena easily reproduce and this is due to how their genome is sequenced and available for genetic manipulation. I wonder how far we will go into Tetrahymena? Will we conduct experiments to manipulate their genome?
Getting Ready for “Experimental Design”
During lab we worked with our partners to design an experiment to be performed on Tetrahymena. We decided to test how Tetrahymena are effected by microplastic pollution. Microplastics are pieces of plastic that are less then 5mm big. Our experiment will consist of 3 different enviorment. The first group being the control will have Tetrahymena only to track normal growth, function, and behavior. Then the other two environments will have different concentrations of microplastics within the environment with the Tetrahymena. One group will have a small amount of microplastics while the third group will have a high concentration. Then over time we will observe how the Tetrahymena are effected by the different concentrations. The independent variable is the amount of microplatics we decide to include in the environments. The dependent variables will be the outcome such as the Tetrahymena’s cell structure, behavior, function, reproductive rate, appearance, and life span that have been changed from the pollutants.
The question being asked is how are tetrahymena affected by microplastics in their environment? My hypothesis is that the more microplastics in the environment the less successful the Tetrahymena will be. For example, they will have slower reproduction rates, slower movement, less function, and a change in shape. I will test these ideas in the procedure listed above. Data will be taken by observing each environment over time. I will measure growth, function, behavior, reproduction rate, movement, and appearance. Results will be analyzed by comparing results at the end to the beginning.
Micropipetting
Lastly in pre-lab and lecture we learned how to use a micropipette. This was my first experience with a micropipette but I had a lot of fun. In lecture we got a demonstration about the dos and donts. We learned how to calibrate it to the desired volume. We had to be careful to not set it above or below its capacity (found on the pipette) as it would become uncalibrated. Then we learned how to put the proper tip onto the pipette shaft. We practied transporting various volumes of water. Once we mastered the skill we used the pipettes to put Tetrahymena samples onto concavity slides. A micropipette’s 1000µL=1mL and 1000mL=1L. I wonder how many student in class have previously used a micropipette? I wonder if anyone used it incorrectly?
Purpose
The purpose of this lab is to work on skills using a micropipette, dissecting scope, and compound microscope. Get aquainted with Tetrahymena and develope a scientific experiement which involves them in addition to microplastics. Lastly, find an article to enter us into the mind frame of Tetrahymena and microplastics.
Objective
To get familiar with the model organism Tetrahymena. Also to develope new skills with a micropipette in addition to reviewing the dissecting and compound microscope. Another objective is to correctly find a primary source and identify what makes it good. Lastly, to create an experiment using Tetrahymena and microplastics.
Hypothsis
My hypothesis is that students will enjoy observing a new ciliate. Collaborating with their lab partners will increase creativity to think of a experiment. This will assist in combining science and creativity in a relaxed environment. Lastly, I think students will be able to find article on Tetrahymena or microplastics but not together as I don’t think there is a lot of research done on those two combined specifically.
Procedures
Wet Mount
- Transfer 100 µl of Tetrahymena stock culture to a clean well using the correct micropipettor.
- Observe Tetrahymena in 24 well-plate with dissecting microscope.
- Pick 5 µl of cells using a P-10 micropipette
- Transfer 5 µl to concavity slide and observe on 4x and 10x using the compound microscope.
- How many cells can you count per 5 µl?
- Using FOV measurements, approximate the diameter of Tetrahymena
- Record your procedure and observations in lab notebook.
Data
| Trial # | 1 |
| # of cells in 5 µm | 300 |
| Approximate diameter of cells | 170 |
| Diameter in mm | Mag: 4x = 4mm |
| Diameter in µm | Mag: 4x = 4,000 µm |
| Size of cell in µm | 23.54 µm |
| Drawling |  |
Conclusion
Tetrahymena are very very small. They are very abundant and are great model organisms. They are great for experiments as they reproduce quickly and are cheap. Micropipettes are good for exact measurements and getting a small drop on a slide. I still need to work on my skills to focus a compound microscope. Microplastic pollution is a huge problem even if it is physically small (get it, because its smaller then 5mm). Tetrahymena have been used in a wide variety of experiments so why not see the effects of microplastic pollution on them. There is not many sources on Tetrahymena so as the CILI-CURE class we should research and make our own discoveries.
Next Steps
After today in class I was motivated to help to planet. Be more aware of whats recyclable and make sure all trash is disposed of properly. I am very excited for the opportunity to create my own experiment and test it. Tetrahymena are so cool and have done so much I cant wait to test my theories on them. Once my experiment is done I can use the results to show others the effects of microplastic pollution and how serious of a problem it is.