April 05, 2013
Rutendo Sigauke ‘ 13Hamline UniversityBiology Senior Seminar Abstract:
The Significance of the Protein Phosphatase 1H (PPM1H) gene in Colorectal Cancer (CRC)
A transposon based mutagenesis system was employed to identify genes that are involved in the initiation of colorectal cancer (CRC) in mice. This screen identified dozens of genes that could be involved in CRC development, including genes known to initiate CRC (e.g. APC) as well as novel genes. One gene identified, Ppm1h gene is a tumor suppressor that had not previously been identified as a CRC associated gene. This research investigates the role and significance of the Ppm1h gene in human CRC using short hairpin RNA fragments (shRNA) to knock down Ppm1h gene expression in the CRC cell line, DLD-1. Cells transfected with empty vector plasmids were used as a negative control. Cell death in DLD-1 CRC cells was induced with 5-Fluorouracil (5FU), an anti-metabolite, at different doses. Apoptosis was measured using Annexin V-FITC, which binds to phosphatidylserine, and fluorescently tags cells in the early stages of apoptosis. Cells were simultaneously stained with Propidium Iodide (PI) to select for necrotic cells. Results obtained were inconclusive; however there may have been a some resistance to apoptosis in cells in which the Ppm1h gene expression was silenced. This was overall consistent with the hypothesis that suggests that Ppm1h is a tumor suppressor. Mutations in this gene can cause resistance to cell signals that initiate apoptosis in CRC cells among other signaling pathways. Further research in other cell lines is yet to be done to confirm these observations.
Jackie Brigl ‘ 13Hamline UniversityBiology Senior Seminar Abstract:
The Effects of Insect Repellant, (DEET) on the Decomposition Process in Pigs
Forensic science is a highly important area of science that directly correlates with the judicial system. It is extremely important to be precise, efficient, and accurate, when handling evidence, running tests, and interpreting data in the field of forensic science. This is not only important to maintain the credibility of science itself, but it is also important because the results of these tests directly affect individuals involved in crime. When a body of a homicide is found, the medical examiner is instructed to determine the time of death so that investigators can start developing leads and finding suspects. The Forensic Archaeology Organization states that in order to contribute to solving legal issues it is important to accurately estimate the amount a time a person has been dead (2012). Many internal and external factors affect the rate at which decomposition occurs, and it is important to scientifically know how to interpret and properly analyze these factors. For my biology seminar I chose to discuss research performed by Shelomi et al from the paper, “DEET (N,N-Diethyl-meta-toluamide) induced Delay of Blowfly Landing and Oviposition Rates on Treated Pig Carrion (Sus scrofa L.) from the Journal of Forensic Science. The paper investigates how insect repellent effects decomposition on pigs by measuring the arthropod activity occurring on each pig. Using entomological science of the study of insects they were able to determine the rate of decomposition of each pig, comparing a control set of pigs and the sprayed DEET set of pigs. The times that it took for flies to arrive was noted, as well as first egg mass, life cycle processes, and finally total maggot volume was measured after the study was completed. The study concluded that blowflies visited the DEET- treated pigs later than they did control pigs. Overall the control pigs decomposed faster than the DEET-treated pigs and statistical data collected from the study was significant. The paper suggests that DEET makes pigs less appealing for flies to lay eggs and continue their life cycle on, which causes the delayed decomposition process. It is important to investigate factors such as this that affect decomposition rate to further ensure that forensic science’s postmortem interval or estimated time of death is accurate. This type of finding is especially important in the findings of corpses of hikers, or those found in more outdoorsy environments because they are likely to have insect repellent and having the knowledge to incorporate this into the other evidentiary findings is crucial to serving proper justice, as well as having accurate science.