May 13, 2016

Unnatural Killer Cells: Targeting Circulating Tumor Cells by Coating Leukocytes with the Apoptosis-inducing Ligand TRAIL

Deontray Walker '16

Metastatic dissemination, the spread of cancer cells through the bloodstream from the initial tumor to a distant organ, is said to account for over 90% of cancer-related deaths. Research has shown that these cells can adhere to the walls of blood vessels, a process mediated by selectin, much like leukocyte trafficking during inflammation. This study coated the surface of leukocytes with the cancer-specific TNF-related apoptosis inducing ligand (TRAIL) along with E-selectin adhesion receptor, to target and kill colon and prostate cancer cells in the blood. This technique resulted in ‘unnatural killer cells’ which mimicked the cytotoxic activity of natural killer cells in humans in vitro, and mice in vivo. TRAIL coated leukocytes may be an effective and safe way to target and kill circulating tumor cells before they metastasis.

The Effects of Trout Predation on Zooplankton Community Structure and Water Quality: A Neo- and Paleolimnological study

Chris Conley '16

In 2009, Square Lake was ranked the clearest of the Twin City metropolitan lakes and ranked in the top 1% for water clarity in the state. However, its water clarity has been steadily declining since 1980. In 1974, the Minnesota DNR began stocking rainbow trout in Square Lake, a predator that consumes the large-bodied zooplankton Daphnia pulicaria. It is believed that induced a top-down trophic cascade, causing the decline in water clarity. The MNDNR agreed to suspend stocking efforts from 2012 to 2015 to allow for the evaluation of the effects of trout stocking on Square Lake. PURPOSE: To determine what effect the stocking of rainbow trout has had on the food web structure and water quality of Square Lake using neolimnological and paleolimnological methods. METHODS: Neolimnological data compared Secchi depth, total phosphorus, and chlorophyll-a levels of pre-moratorium (1980-2012) Square Lake to moratorium (2012-2015) Square Lake. Daphnia population density was measured during the moratorium and compared to the population density measured during 2010 and 2012, prior to implementation of the moratorium. Paleolimnological data compared the number and size of Daphnia ephippia found in sediment core samples taken from Square and Big Carnelian Lake, which has never been stocked with trout. Three sediment cores were obtained from both Square and Big Carnelian Lake. One core from each lake was extruded and analyzed in the lab for Daphnia ephippia. Ephippia were obtained by centrifuging 1 cm3 of sediment from each sample in 15ml of glucose solution, then counted, measured, and identified. RESULTS: The neolimnological data showed an increase in water clarity, and an increase in D. pulicaria population, during the moratorium. The paleolimnological study showed a decreasing trend in the ephippia size of D. pulicaria in Square Lake when trout were present, while no significant trend in ephippia size was observed in Big Carnelian Lake. The extruded core samples from Square Lake exhibited a general increasing trend in ephippia number as the samples became more recent, whereas the extruded samples from Big Carnelian Lake did not exhibit this trend. CONCLUSION: The results of our studies show that changes to the food web due to the stocking of rainbow trout is the cause of decreased water clarity and quality in Square Lake.