Biology Commons^™

Investigating Dose-Dependent, Multi-Generational, And Strain-Specific Effects Of 17Α-Ethynylestradiol Exposure In Zebrafish (Danio Rerio), Decatur Mitochondria Foster

Dissertations and Theses

Endocrine disrupting chemicals (EDCs) pose a threat to biodiversity at the individual, population, and ecosystem level, as they can interfere with processes that are responsible for regulating metabolism, development, behavior, and reproduction in living organisms. 17α-ethynylestradiol (EE2) is a synthetic estrogen and EDC utilized in pharmaceutical and livestock industries, and contaminates waterways worldwide. This research explores the effects of dose-dependent and multi-generational exposure of EE2 in three strains of zebrafish. High dose (10-25 ng/L EE2) exposure led to complete reproductive failure, as well as significantly decreased survival and growth. A period in clean water (depuration) after exposure allowed for some …

Battle Of The Buttercups: Investigating Hybrid Zone Dynamics In A Ranunculus Species Complex, Jessica Persinger

Dissertations and Theses

Plants pose a well-known challenge to the biological species concept because hybridization is a common occurrence. Range dynamics have a crucial role in determining whether species are given the opportunity to interbreed or not. Successful hybridization can be of particular concern when considering range-limited species and their persistence. In my thesis research, I examine the apparent hybrid zone between the southern Oregon endemic Ranunculus austro-oreganus, a candidate threatened species due to its limited range, and its widespread congener, Ranunculus occidentalis, whose range spans from California to Alaska. The discovered contact zone was recognized in populations which contained apparent …

Assessing Well-Being Of Asian Elephants (Elephas Maximus) Through Major Events And Transitions, With Development And Aging, And Husbandry Changes, Sharon Stuart Glaeser

Dissertations and Theses

In this body of research, reproductive and adrenal hormones and behavior were used to evaluate individual and group responses to physiological, social, and environmental changes in zoo-housed Asian elephants, considering factors of sex, age, and life stage. Animals experience physiological, social, and environmental changes as part of their natural history and individual life experience. Measures of both positive and negative states are needed to assess the impact of these changes at the individual and group level. Such measures can help us better understand how animals cope with a changing environment, and can help inform management decisions. Through longitudinal analyses of …

Energy Stores And Life-History Transitions In Red-Sided Garter Snakes (Thamnophis Sirtalis Parietalis), Rachel Catharine Wilson

Dissertations and Theses

All organisms must prioritize investment in either reproductive or self-maintenance activities. Despite this established paradigm, our understanding of how organisms choose to prioritize certain behaviors and physiologies over others remains limited. It is likely that an organism's energy status not only influences variation in reproductive effort, but also transitions to and from reproductive activities. My dissertation aims to investigate how energy metrics (body condition index, adipocyte follicle size, and liver glycogen) relate to reproduction and associated life-history stages in red-sided garter snakes (Thamnophis sirtalis parietalis). Chapter two examines if energy metrics differ with migratory status and sex in …

No Oxygen, No Water: The Unique Physiology Of Annual Killifish Embryos Across Development, Daniel Erik Zajic

Dissertations and Theses

For most vertebrates, an abundance of oxygen is necessary for the production of ATP and the maintenance of cellular homeostasis. The absence of oxygen, even for brief periods, quickly leads to ATP depletion which can lead to irreparable damages to sensitive organs, such as the brain and heart. However, certain vertebrates demonstrate an extraordinary ability to thrive and recover fully from periods of no oxygen (anoxia). The annual killifish (Austrofundulus limnaeus) lives in ephemeral ponds in the Maracaibo basin of Venezuela and their embryos have the remarkable ability to not only survive anoxic periods for months, but also …

Short- And Long-Term Impacts Of A Deliberative Pedagogy In Introductory Biology And Chemistry Courses, Liz Rain-Griffith

Dissertations and Theses

There have been multiple national calls for curricular reform in college-level science, technology, engineering, and mathematics (STEM), including a need to instill democratic skills in students. Democratic skill building can be embedded in STEM classrooms through intentional "deliberative pedagogies" which include skills in: communication, collaboration, and application. We developed and implemented a deliberative pedagogy, Deliberative Democracy (DD), across introductory majors and non-majors biology courses and a majors chemistry course. In two separate studies, I took a longitudinal, qualitative research approach to understand introductory biology and chemistry students' experiences and perceptions of DD. For the first study, I tracked a cohort …

Sensing Malignancy: Expanding Upon The Nematode Scent Detection Test, Morgan Alexandra Thompson

Dissertations and Theses

With the growing prevalence of cancer worldwide, research has increasingly focused on methods of early detection since the early detection of cancer can dramatically improve health outcomes for affected individuals. Ideally, early detection systems would be highly reliable yet cost-effective and easy to use. Toward development of such a system, Hirotsu et al. (2015), developed a "Nematode Scent Detection Test" (NSDT) that capitalizes upon the attraction of Caenorhabditis elegans nematodes to various tissue samples from cancer patients to detect multiple types and stages of cancer. However, it is currently unknown which G-protein coupled receptors (GPCRs), and/or ligands interacting with theses …

Morphology, Taxonomy, And Ecological Niche Modeling Of The Cochabamba Grass Mouse, Akodon Siberiae Myers & Patton, 1989, James George Dunn

Dissertations and Theses

The Cochabamba Grass Mouse, Akodon siberiae, is a small mouse (mean head+body length: 103 mm, N = 22) that occurs in a spatially restricted range in the Bolivian Yungas forests, the cloud forest transition zone between lowland Amazonia and the Andean Altiplano. Like many species in the genus, their appearance is very similar to that of other species in the genus: they are difficult to distinguish from their congeners, and are challenging to identify. In the absence of molecular data, A. siberiae specimens require a thorough and careful analysis of external and cranial features for identification. Furthermore, Akodon …

Biogeography, Morphology, And Systematics Of The Mountain Cottontail, Sylvilagus Nuttallii (Bachman, 1837), Mammalia: Lagomorpha: Leporidae, Johnnie H. French

Dissertations and Theses

Widespread species often present taxonomic conundrums: are they truly a single panmictic species, or, is the widespread species in fact a polytypic species complex constituted by independently evolving, morphologically or otherwise cryptic species? One such broadly distributed taxon is Sylvilagus nuttallii, with distribution across the western United States, ranging from South Dakota to California, and from Canada to Arizona. The three subspecies constituting S. nuttallii are, however, geographically isolated and it has been hypothesized that they likely constitute independent, species level taxa. However, that study examined only two of the three holotypes, rather than broader geographic and non-geographic variation. …

From Theory To Practice: Interdisciplinary Science In Undergraduate Education, Brie Tripp

Dissertations and Theses

Science has undergone a major transformation in the 20th and 21st centuries with new fields emerging at the intersection of disciplines, such as bioethics, bioinformatics, and chemical ecology. Yet, opportunities to engage with interdisciplinary science, and the skills needed to work in these fields, are largely absent from undergraduate biology classrooms. As a consequence, students are potentially deprived of opportunities to think interdisciplinarily and engage with real-world issues that often necessitate interdisciplinary efforts. To be informed citizens in society and forward-thinking scientists in the workforce, undergraduate students will undoubtedly benefit from exposure to these interdisciplinary science experiences.

Given these considerations, …

Lack Of Replication Disruption Following H2o2-Induced Damage In Escherichia Coli, Sierra S. Schmidt, Justin Courcelle, Charmain T. Courcelle

University Honors Theses

Hydrogen peroxide (H₂O₂) toxicity has long been thought to be predominantly due to oxidative DNA damage that can disrupt DNA replication and result in lethality. Curiously and contrary to this view, it is also well established that the glycosylases responsible for repairing oxidized-base damage are as resistant as wild-type cells when treated with H₂O₂. The observation raises the possibility that H₂O₂-induced DNA damage does not disrupt or prevent replication. To examine this possibility, I examined the sensitivity of recF mutants to H₂O₂. RecF is …

Developmental Programming Effects Of Maternal Obesity, Carolle J. Kassab

University Honors Theses

Population studies within the United States indicate increasing rates of obesity, considerably prominent for women within reproductive age. Maternal obesity is associated with the offspring’s hyperlipidemia, diabetes, and cardiovascular disease, which have chronic consequences. Obesity in pregnancy causes metabolic and epigenetic perturbations within the fetal environment, disrupting future health of offspring. This phenomenon is known as developmental programming. Although the relationship between maternal undernutrition and developmental programming has been demonstrated, its relationship to maternal obesity remains understudied.

Long Term Effects Of Concussions And The Frequency Of Injury To The Different Regions Of The Human Brain, Marissa S. Swadener

University Honors Theses

Concussions, or mild traumatic brain injuries, do not have a universally accepted definition but there are key features that the experts agree upon; most notably that they are caused by a direct blow, they cause functional disturbances, and that they cannot be explained by another injury or impairment. Most concussions are resolved within a few days but 10-20% have lingering effects that can last for years. In this study, frequency of lingering injury to each brain region was determined from data from thirteen studies and compared to Scheid et. al's frequency of short term injury by brain region using ANOVA …

Screening For Candidate Genes Involved In Opioid Addiction In Reduced Complexity Cross Between B6j And B6nj, Jeya Aishwarya Anandakumar

University Honors Theses

Drug overdose epidemic has worsened dramatically in the past 10 years. Opioid use disorder (OUD) is one of the biggest contributors to this rise. OUD has been a national public health and socioeconomic crisis. In 2017, the Center for Disease Control (CDC) has reported 47,600 opioid overdose deaths in the US alone. This amounts to 68% of all deaths due to drug overdose. Currently, 2.1 million Americans are suffering from OUD. The economic burden due to opioid misuse treatment was 171.7 billion US dollars in the year 2009 in the U.S. The projected cost in 2020 will be 280.5 billion …

Proposal For Comparative Morphometrics Of Tübingen (Tu) And Tübingen Longfin (Tl) Zebrafish (Danio Rerio), Andrew Draper

University Honors Theses

The TL strain of zebrafish (Danio rerio) originated from the TU strain, and differs in fin pattern with a phenotype predominated by increased fin length. Two genes are known to affect the phenotype: leo and lof. The pattern-affecting leo gene is not believed to affect the growth rate, development, or proportionality of the body. The lof gene does however result in significant increase in fin length compared to the wild-type phenotype of TU. Using populations from both TL and TU genetic strains, development was observed from 48 hours post fertilization through sexual maturity at 90 days post fertilization …

Impact Of The Urban Heat Mosaic On The Leaf Senescence In Two Acer Species, Jeffrey D. Smith

University Honors Theses

Due to the heterogeneity of the urban heat island, we can think of the variable influence of urbanization on air temperature as more of an urban heat mosaic. Climate change has caused a resurgence of interest in the way temperature affects how organisms, such as street trees, undergo cyclic changes in their life cycle. Such changes include budburst or, less commonly, timing of senescence. Little is known about how the urban heat mosaic could be affecting the phenology of different urban trees. Because street trees are one of the more prominent ecosystem engineers of the urban landscape, variable influences of …