Tag: Poster 42

The Genetics of Speciation in C. remanei: Post-Zygotic Isolation and Genetic Incompatibilities

Presenter: Max Ryan

Mentor: Patrick Phillips

PM Poster Presentation

Poster 42

Earth is home to an amazing amount of diversity, but the mechanisms through which new species arise are not well understood. Speciation, the study of these mechanisms, is a relatively young field, with significant research only conducted within the past 30 years. Since the start of this research, a large number of reproductive isolating barriers have been identified that inhibit gene flow between species. One such barrier is known as genetic incompatibility, wherein genes of different species, when mixed together in hybrid offspring, interact negatively. These negative interactions hinder the development of offspring, thus ensuring the two species remain isolated. In this study, we research genetic incompatibilities between two different populations of the soil nematode Caenorhabditis remanei. Initial research suggested that genetic incompatibilities arise in the second generation of inbreeding between the two populations, when the process of recombination introduces genes from both genetic backgrounds onto the same chromosome. This result led to further research into genetic incompatibilities between the two populations, focusing on the egg-to-adult viability of ten different combinations of mating crosses. The results of these assays confirm the existence of genetic incompatibilities between these two populations, with the genes likely involved in the incompatibilities located on the X-chromosome. Genome mapping is being conducted to identify possible genes. Through research like this, earth’s diversity may be understood.

Examination of Executive Function Measurements in Healthy Adolescents and Young Adults

Presenter : Madison Murray

Mentor : Li-Shan

Major : Biology

Poster 42

Executive function has been defined as the ability to utilize external stimuli in order to plan purposeful action. It is thought to be im- portant for tasks like problem solving and decision-making. As the adolescent brain has not yet reached full maturation and is under- going rapid development particularly in the frontal lobe, where executive function is considered to take place, it may be vulnerable to trauma during this time of life. Due to the continued development of the frontal lobe in the adolescent brain it was hypothesized that healthy adolescent individuals would have decreased executive function ability when compared to healthy young adults. The Attention- al Network Test and the Task Switching Test were administered to 14 healthy individuals (7 adolescents, 7 young adults) five times over a period of two months. Testing was carried out 1 week, 2 weeks, 1 month, and 2 months after the initial testing. Testing was performed in a computer lab to free from noise or visual distractions. Young adults displayed faster overall reaction times, however contrary to our hypothesis; preliminary data has shown that adolescents have increased executive function ability compared to young adults. Further research will examine the effects of concussion of the adolescent brain compared with an adult brain. In order to make an accurate comparison between concussed individuals we must first compare healthy individuals.

Using Zebrafish Models of Usher Syndrome Type 2A to Investigate Retinal Cell Function and Survival

Presenter: Kimberly Lerner

Mentors: Monte Westerfield and Jennifer Phillips, Biology

Poster: 42

Major: Biology 

Usher syndrome is a hereditary disorder and the main cause of deaf-blindness. Patients diagnosed with Usher syndrome experience hearing loss and progressive blindness due to photoreceptor degeneration. The most common form of Usher syndrome is type 2A, which is caused by mutations in the USH2A gene. Although gene therapies for some forms of Usher syndrome are being actively researched, current gene replacement methods are not feasible for USH2A patients due to the large size of the USH2A gene. Zebrafish orthologues of Usher genes can be used as models of human Usher syndrome, and our research will contribute to the use of zebrafish as a model of USH2A. Three different mutations targeting different regions of the gene will be characterized in this study, with a specific focus on the ush2asa1881 mutant. Usherin forms a complex with other Usher type 2 proteins at the base of the connecting cilium in order to load ciliary cargo on this transport system between the inner and outer segments of the photoreceptor cells. We studied the co-localization of other known Usher proteins in the ush2asa1881 mutant background, to see if a mutant form of Usherin disrupted the normal localization of these other proteins. The accumulation of photoreceptor cell death in the retina over time leads to progressive vision loss in human USH2A patients. It may be difficult to see progressive retinal degeneration occur over the much shorter life span of the zebrafish, and mouse models of Usher syndrome have a mild retinal phenotype compared to the degree of vision loss that human patients experience. We devised a system that would challenge the retina to see if we could accelerate the damage that is normally accumulated over a longer period of time. Our findings will be useful in that we have created a functional zebrafish model of USH2A, and our results provide the foundation for a potential treatment though the protection of the retina.

The BAH Domains of the DIM-2 DNA methyltransferase Are Required for DIM-2 Localization and Normal DNA methylation

Presenter: Sabrina Abdulla

Faculty Mentor: Eric Selker, Vincent Bicocca

Presentation Type: Poster 42

Primary Research Area: Science

Major: Biology

Funding Source: OURS (Oregon Undergraduate Researchers in SPUR), NICDH, $4500

The regulation of epigenetic marks, including histone modifications and DNA methylation, is critical for normal development. Defects in the processes that regulate epigenetic marks can lead to the development of diseases, including cancer. To better understand these processes, we utilize the model organism Neurospora crassa, a filamentous fungus that possesses many epigllmerenetic marks that are common to higher order eukaryotes, including humans. Using this model, we have investigated the functional requirements of the DNA methyltransferase DIM-2, which is responsible for all DNA methylation in Neurospora. Using site-directed mutagenesis to systematically disrupt regions of DIM-2, and Southern blotting to assay DNA methylation, we discovered that the bromo-adjacent homology (BAH) domains of DIM-2 are required for normal DNA methylation activity. Based upon these observations, we hypothesized that the BAH domains are essential for making specific interactions with histone residues, and that these interactions are necessary for DIM-2 methyltransferase activity. To test this hypothesis, we utilized a DNA adenine methyltransferase (DAM) construct that allowed us to test the ability of the protein to localize to regions that are normally methylated based on the presence of adenine methylation. These experiments revealed that disruption of the BAH domains is sufficient to eliminate DIM-2 chromatin localization. Thus, the BAH domains prove to be essential for DNA methylation due to their role in DIM-2 localization.

Stress in Your Spit? A Literature Review of The Correlation (Relationship) Between Salivary- Alpha Amylase and the Body’s Reaction to Stress

Presenter(s): Robyn Wright − Human Physiology

Faculty Mentor(s): Jenefer Husman, Shawn Lampkins

Poster 42

Research Area: Science

Salivary-alpha amylase (sAA), a protein enzyme, is a biomarker of psychological stress. Researchers have used sAA to study the body’s processes during stress and its influence on health and human behavior. To conduct future research on students’ responses to exam stress using sAA, we first needed to understand the use of sAA as a biological marker and the best methods of collection and analysis. We conducted a literature search using Google Scholar and Web of Science, using keywords such as “salivary alpha amylase”, “sAA”, “salivary alpha amylase stress tasks”, and “sAA stress”. In six of the eight articles sources we reviewed, we found a strong correlation between the body’s enzymatic activity and the sympathetic and parasympathetic nervous systems. This search provided evidence for the proposition that increases in physiological stress are matched by an increase in sAA level in spit. Several methodological issues related to collecting sAA were identified. Passive drool or salivettes, rolls of cotton that subjects chew on, have consistently proven to be a reliable, accurate collection method. Our literature search also revealed sAA response to stress is faster, ten minutes between activation and release, than other salivary markers (e.g., cortisol). Based on this review, we are confident that sAA is a biological marker for stress and that salivettes are a reliable and accurate method of collection. In the future, we will utilize the results of this literature review to guide our examination of classroom context on students’ stress responses during midterm exams in a critical gateway course on statics.

The role of daf-16 in C. elegans response to alcohol

Presenter(s): Haley Rice

Co Presenter(s): Faryn Dahlen, Victoria Dang, Cindy Le, Yalin Li, Jack Lien, Tawny Nguyen, Hanson Pham

Poster 42

Session: Sciences

All organisms experience various stressors in their environments. Model organisms provide a powerful opportunity to investigate the mechanisms by which organisms cope with these challenges. In the nematode model C. elegans, daf-16 is a global stress regulator. Our research focused on testing the role of daf-16 in the organismal response to alcohol exposure to understand the function of this gene. C. elegans with the daf-16 mutation have a reduced ability to respond to stressful environments. We predicted that daf-16 mutants would be less able to respond to ethanol, resulting in lower survival compared to wild-type. We sought to determine whether daf-16 mutants are able to respond to alcohol in a manner comparable to wild-type. After incubation in a weak ethanol solution, we exposed groups of wild-type or daf-16 worms to either acute alcohol stress (10% EtOH; treatment) or to a buffer (control). After five minutes, we counted the number of alive and dead C. elegans and calculated percent survival in both wild- type and daf-16 in both solutions. Our data indicate a significant effect of alcohol on survival, though the magnitude of the reduction in survival in response to ethanol is modest. Our data further indicate no significant effect of genotype on survival in response to ethanol exposure. From the collected data, we concluded that the daf-16 mutation has little to no effect on the alcohol-associated stress response of the C. elegans. Future work will be aimed at determining the role of daf-16 in organismal responses to other stressors.