Scientific Inquiry
Investigation and Research III
Comparison of Propofol and Capsaicin Induced Currents in DRG cells and CHO Cells Expressing TRPV1
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Abstract: Transient receptor potential (TRP) channels have an important role in pain sensing mechanisms. Capsaicin, the active ingredient in chili peppers, is known to activate TRPV1 channels. Neurons of the dorsal root ganglion (DRG) carry pain signals to the CNS when capsaicin activates TRPV1 channels that ultimately results in a painful sensation. Propofol, a commonly used anesthetic, is known to cause pain at the injection site. Our previous data suggests that propofol has the capability to activate TRPV1 channels in DRG neurons. However, the mechanism by which the TRP channel is activated is unknown. Therefore, the purpose of this study was to compare the effects of propofol and capsaicin on DRG neurons isolated from rats and Chinese Hamster Ovary (CHO) cells expressing TRP-V1 channels. Whole-cell patch clamp was used to compare currents elicited by propofol and capsaicin. We hypothesized that propofol may cause pain by activating TRPV1 channels. (75%) and (53%) of small DRG neurons (≤40 pF) responded to propofol and capsaicin, respectively, by activating an inward current at -60 mV. (78%) and (75%) medium neurons (≥40 pF) responded to propofol and capsaicin, respectively. CHO cells (n=12) stably expressing TRP-V1 responded to capsaicin with a large inward current. Moreover, like in DRG neurons, the response to propofol was much less -92 ± 38 and -1288 ± 462 pA (for propofol and capsaicin, respectively). Our results suggest that propofol does indeed activate a TRP-like current in isolated rat DRG neurons and CHO cells expressing TRP-V1. However, the difference in responses suggests that propofol may activate different types of TRP channels other than TRP-V1, or the same channels via different mechanisms. Further experimentation needs to be done to determine the effect each chemical has on different TRP channels.
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For more information, see the poster link.
Scientific Writing
Predator and Prey Interactions
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Abstract: Predator and prey interactions are known as a competition. There are, however, many variations of how these interactions can take place. The hypothesis for this experiment was that the more prey distributed in a certain area, the more the predator would eat. There was an area used where small squares were to be placed randomly as the prey. Three people were used: one person was the predator, one was the time keeper, and the other was to assist the predator by placing the prey back within the area used. After doing the experiment, the hypothesis was rejected. The amount of prey that is eaten is entirely based on the predator.
For more information, see link for lab report.
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Microbiology
The Streak Method Lab Report
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Introduction: Why is the streak plate method used in the lab for microorganisms? In the lab, we learned how to carry out this technique and found out that there are many things the streak plate method can determine. Cells can be grown in liquid or solid cultures. The streak plate method is used to isolate pure colonies, using solid cultures. Streaking occurs to dilute the cells in order for this colony to form. Many kinds of media can be used for this technique. It is most influential to use selective media and/or differential media. Selective media favors the growth of a specific microorganism. An example of selective media is the dye tests, like crystal violet, favors the growth of gram negative bacteria while it inhibits the growth of gram positive bacteria. Although it takes on this role, the gram negative bacteria is not affected negatively. Differential media distinguishes between different groups of bacteria and based on biological characteristics, microorganisms can be identified. An example of differential media could be blood agar. Blood agar distinguishes between hemolytic and non-hemolytic bacteria. In this lab, we were to use four different solid medium agar plates, which include: Mannitol Salt agar plate, Eosin methylene blue agar plate, MacConkey agar plate, Phenylethyl alcohol agar, and a Nutrient agar plate which was used as the control in this experiment. The Mannitol Salt agar plate is both a selective and a differential medium. The selective medium contains 7.5% of sodium chloride. It favors the growth of Staphylococcus but inhibits growth of most bacteria. The differential medium distinguishes between Mannitol fermenters and non-fermenters. If the bacteria can ferment Mannitol, it releases acidic products, which turns the agar from red to yellow. An example of bacteria that can ferment Mannitol is Staphylococcus aureus. If the bacteria cannot ferment Mannitol, it will remain red. An example of bacteria that cannot ferment Mannitol is Staphylococcus epidermidis. Another agar plate that was used in this streak plate method was the Eosin methylene blue (EMB) agar plate. This plate was also both a selective and a differential medium. The selective medium favors the growth of E. coli and other related bacteria. It partially inhibits the growth of gram positive bacteria. In this agar plate, there was both dye eosin and methylene blue. The differential medium distinguishes between gram negative lactose fermenters compared to non-lactose fermenters. The lactose fermenters released acidic products because of the way they react with the dyes. There are blue-black colonies seen with a metallic sheen. An example of a gram negative lactose fermenters is E. coli. There are also some bacteria lactose fermenters that show pink or red colonies, known as Enterobacter. The lactose non fermenters are colorless to amber colonies and examples of these include: salmonella, Proteus, and Pseudomonas. The MacConkey agar plate is also both a selective and a differential medium. The selective medium favors the growth of gram negative bacteria and inhibits the growth of gram positive bacteria via bile salts and crystal violet. The differential medium distinguishes between gram negative lactose fermenters and non-fermenters. It also distinguishes these from the non-lactose fermenters. The lactose fermenters release acidic products resulting in red colonies. The non-lactose fermenters do not release acidic products, creating colorless colonies. The Phenylethyl alcohol agar plate is a selective medium only. It favors the growth of gram positive organisms and inhibits the growth of most gram negative organisms. There are many goals set for this exercise in the lab. The first is for students to understand how to create a streak plate technique on a petri dish. Another is to understand the difference between selective and differential medium. The main goal of this experiment is to find the unknown of many different bacterium using the streak plate method on various agar through the characteristics seen on the plates.
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For more information, see link for lab report.
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