Analysis of Long-term Trends in Monarch Chemical Defenses

Common milkweed, Asclepias syriaca, produces steroid compounds called cardenolides to deter herbivores.  Cardenolides interfere with the function of the sodium potassium pump in cells and can disrupt heart rhythm.  In addition to this, they have an unpleasant, bitter taste.  Monarch butterfly caterpillars exclusively eat milkweed species.  They are able to do this by sequestering the cardenolides they consume.  The cardenolides stored by the monarch provide it with chemical defenses as both a caterpillar and an adult.  Monarch butterfly populations have been declining due to a multitude of causes.  One threat to monarch populations is predation by birds as they overwinter in Mexico.  Cardenolides have been shown to deter birds from eating monarchs.  Asclepias species have been declining in abundance as well, but  A. syriaca has adapted to modern land use practices better than other, more toxic species.  We predict that as the relative abundance of different Asclepias species has changed, a greater proportion of monarch caterpillars has fed on A. syriaca.  A. syriaca produces much lower levels of cardenolides than some other milkweed species.  The amount of cardenolides stored by monarchs is related to the amount of cardenolides in their diets overall.  Monarchs that fed on less toxic milkweed plants as caterpillars will be less chemically defended as adults.  This project will assess whether monarch butterflies have become less toxic over the past century as their diet has shifted towards weakly toxic A. syriaca and away from other, more toxic, milkweed species.  I will use High Performance Liquid Chromatography to analyze the cardenolide levels of monarch butterfly samples from the midwestern breeding population.  I will aim to use 100 butterfly samples that were collected between 1900 and today.  I will also assess A. syriaca samples from the same geographical range and time period to control for a change in cardenolide production by A. syriaca.

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Eating Norms

My project will be a follow-up study focusing on the eating behavior of individuals. Research has shown that people tend to alter their eating behavior depending on who they are around and what the other person is consuming. We hypothesize that when there is a confederate present during the experiment who is eating a healthy food item, the participant will demonstrate more of an attentional bias in the flanker task. This suggests that they have an increased desire for the healthier foods (that was eaten by the confederate). Furthermore, if the confederate is eating an unhealthy food, the participant will show more of an attentional bias towards the unhealthy food. Also, to test the effect of the confederate, we have a healthy or unhealthy food in the testing room without the confederate present.

Abstract: The Interaction of MK-STYX and the Ubiquitin Proteasome System

MK-STYX is a pseudo-phosphatase that has recently been indicated in many cellular processes, including the stress response pathway. Cells under stress often lose the ability to function properly, which leads to the build-up of misfolded proteins and untranslated mRNA. As a protective mechanism, cells isolate these non-functional molecules into aggregates called stress granules. Over time, stress granules become toxic to the cell, and can cause apoptosis. Our previous research showed that the expression of MK-STYX decreased the amount and size of stress granules within the cell. We also found that this interaction does not prevent stress granules from forming, so we hypothesize that MK-STYX helps to clear them (Barr et al, 2012). We found that MK-STYX co-localizes with the protein HDAC6, which is involved in proteasomal degradation (Cao, 2017).

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Summer 2019 Research Abstract

The main goal of this research project is to understand the effect that MK-STYX has on the regulation and treatment of stress granules within cells. MK-STYX is a member of the protein tyrosine phosphatase (PTP) family, however it lacks the essential cysteine in the PTP signature motif that is necessary for catalysis. My individual research, specifically, will look into how MK-STYX affects the localization of TFEB (transcription factor E-Box), a gene that has significant control on cellular autophagy, a process that regulates stress granules within cells that has a possible connection to MK-STYX and its functions. The findings of this research are hopeful to better understand and treat the many neurological diseases that are connected to the accumulation and lack of cellular regulation of stress granules.

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Tears in Antarctic Ice (ABSTRACT)

 

Recently, due heavily to global climate change, there has been a net loss of ice on and around Antarctica. While part of the ice loss is driven by basal melting, most of it – about 75% — is driven by iceberg calving (Bassis, 2008). Iceberg calving is a process whereby large chunks of ice break off ice shelves and float away, eventually melting into the ocean. The process of iceberg calving begins with rift propagation. Rifts are tears in ice shelves that penetrate vertically through the entire ice shelf, and they start from one horizontal end of the ice shelf and lengthen towards another end.

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