Biology Commons^™

Detecting Bias In Large-Scale Comparative Analyses: Methods For Expanding The Scope Of Hypothesis-Testing With Hormonebase, Michele A. Johnson, C. D. Francis, E. T. Miller, C. J. Downs, Maren N. Vitousek

Biology Faculty Research

To address large-scale questions in evolutionary biology, the compilation of data from a variety of sources is often required. This is a major challenge in the development of databases in organismal biology. Here, we describe the procedure we used to reconstruct the phylogeny of the 474 species represented in HormoneBase, including fish, amphibians, mammals, birds, and reptiles. We also provide the methodology used to compile vertebrate environmental, life history, and metabolic rate data for use in conjunction with the HormoneBase database to test hypotheses of the evolution of steroid hormone traits. We then report a series of analyses using these …

Cold Exposure Effects On Cardiac Function And Synaptic Transmission At The Neuromuscular Junction In Invertebrates, Yuechen Zhu, Robin L. Cooper

Biology Faculty Publications

This review emphasizes how ectothermic animals respond physiologically to environmental temperature changes and cold stress. Generally ectothermic animals cannot generate heat to maintain their body temperature but they can still survive in various temperature zones. Various organisms have been analyzed anatomically and physiologically in the attempt to understand the underlying mechanisms of this temperature adaptation. A few of the changes in the metabolic and molecular function of proteins are discussed. The potential of how hormonal modulation of cardiac and nervous systems which influences responses during exposure cold exposure is also addressed. The focus of this review is on the effect …

The Effects Of Aqueous Nitrate On Freshwater Crayfish, Erik Hartman

Williams Honors College, Honors Research Projects

Globalization and a rising need for greater production from the agricultural system have increased the use of fertilizer by farms across the entire country. The purpose of this experiment was to observe the effects of aqueous nitrate (commonly found in many fertilizers) on the metabolic rate and hemolymph lactate concentration of freshwater crayfish. After exposure, there was no observed change in metabolic rate, but there was a significant decrease in hemolymph lactate concentration in the groups exposed to nitrate.

Fast Voltage-Gated Sodium Channel Currents And Action Potential Firing In R6/2 Skeletal Muscle, Eric Joshua Reed

Browse all Theses and Dissertations

Huntington’s disease (HD) is a degenerative disorder caused by expanded CAG repeats in the Huntingtin gene, which results in cognitive problems as well as muscle weakness, chorea, rigidity, and dystonia. Most research in HD has focused on neurodegeneration, but recent studies have found peripheral defects that may help explain the debilitating motor symptoms of HD. We have shown that skeletal muscle from the R6/2 transgenic mouse model of HD is hyperexcitable due to decreases in resting chloride and potassium currents. Other groups have speculated that the fast voltage-gated sodium channels may be affected in Huntington’s disease as well. To fully …

Osmotic Activation Of Sperm Motility Via Water Flow Through Aquaporins In The Freeze-Tolerant Cope's Gray Treefrog, Dryophytes Chrysoscelis, Deja Miller

Browse all Theses and Dissertations

Gametes of gray treefrogs, Dryophytes chrysoscelis, are deposited into freshwater ponds. Sperm undergo spermatogenesis and maturation beginning in the seminiferous tubules and migrating to the lumen. In mammals and fishes, these cells are immotile within the isosmotic fluid of the testes and have motility activated by exposure to a hyper- or hypoosmotic medium. Water flows into or out of the sperm cell, altering intracellular ionic concentrations, and ultimately stimulates flagellar movement. We tested the hypothesis that exposure to a hypotonic environment activates motility of gray treefrog sperm. We also hypothesized that osmotic water uptake is facilitated by expression of water …

The Influence Of Physiological And Abiotic Factors On The Sensitivity Of The Sea Lamprey (Petromyzon Marinus) To The Lampricide 3-Trifluoromethyl-4-Nitrophenol (Tfm), Alexandra Muhametsafina

Theses and Dissertations (Comprehensive)

Invasive sea lamprey (Petromyzon marinus) in the Great Lakes are controlled using the pesticide (lampricide) 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to nursery streams containing larval lamprey. The toxicity of TFM to lamprey is affected by various environmental and physiological factors, which can lead to residual lamprey that survive TFM treatment. The goal of this study was to investigate how abiotic (season and temperature) factors interacted with physiological parameters (whole body and tissue energy reserves) to influence TFM sensitivity in sea lamprey. Toxicity tests were conducted at different times of the year (spring, early and late summer, fall) and …

Forensic Markers Of Lampricide Toxicity In Oncorhynchsus Mykiss, Chris White

Theses and Dissertations (Comprehensive)

The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) has been used for decades to control invasive sea lamprey (Petromyzon marinus) populations in the Great Lakes, normally with little harm to other fish populations. However, due to the nature of lampricide treatments and the chemical properties of TFM, adverse effects to non-target fishes and non-target mortality occasionally occur. However, investigations of non-target mortality can be complex, particularly if fish deaths are not noticed immediately, due to decomposition of the carcasses. The objectives of this thesis were to expose rainbow trout (Oncorhynchsus mykiss) to TFM in order to: (i) identify forensic markers …

The Role Of Calcium In Regulation Of Glial Cell Line Derived Neurotrophic Factor By Skeletal Muscle Cells, Alicia M. Boynton

Masters Theses

Glial cell line-derived neurotrophic factor (GDNF) is an important signaling molecule for the somatic motor nervous system. GDNF protein is produced and secreted by skeletal muscle cells and helps maintain motor neuron innervation at the neuromuscular junction. Treatment with exogenous GDNF prevents denervation which is characteristic of aging and neurodegenerative disease. The therapeutic potential of GDNF cannot be fully explored without understanding the mechanisms by which GDNF protein production is regulated. The primary objective of this study was to determine the role of calcium in regulating GDNF protein expression by skeletal muscle cells. Skeletal muscle cells (C2C12) were grown in …

Utilizing Modular Labs In Human Anatomy And Physiology: Lessons Learned From A First Time Experience, Jennifer Zitzner

Biology: Faculty Publications and Other Works

Anatomy and physiology laboratory experiences build upon concepts that are presented in the lecture part of the course. Our anatomy and physiology laboratory class meets weekly for approximately three hours and includes a compilation of activities that are to be completed during the laboratory period. While exercises are built off of topics presented in lecture and predominantly hands-on in nature, many students were not taking advantage of the self-directed learning experiences, especially those employing anatomical models. Some students were content to simply take photographs of models with their cell phones and complete only the graded portions of the laboratory assignment …

Effectiveness Of The Flipped Classroom Model In Anatomy And Physiology Laboratory Courses At A Hispanic Serving Institution, Gerardo Sanchez

Theses and Dissertations

A flipped laboratory model involves significant preparation by the students on lab material prior to entry to the laboratory. This allows laboratory time to be focused on active learning through experiments. The aim of this study was to observe changes in student performance through the transition from a traditional laboratory format, to a flipped format. The data showed that for both Anatomy and Physiology (I and II) laboratories a more normal distribution of grades was observed once labs were flipped and lecture grade averages increased. Chi square and analysis of variance tests showed grade changes to a statistically significant degree, …

The Effects Of Carbon Nanotubes And Silver Quantum Dots On Gas Exchange In Arabidopsis Thaliana, Maryam Ibrahim Subaylaa

Graduate Theses/Dissertations

Engineered nanoparticles (ENPs) are increasingly being used in commercial products, and may accumulate in soils when the products are disposed. I examined the effects of two common ENPs, carbon nanotubes (CNTs) and silver quantum dots (Ag-QDs), on plant gas exchange. To do this, I grew Arabidopsis thaliana in soil (n=36) for 6 weeks and added a CNT suspension at increasing concentrations (10, 30, 90, 150, 190, 250 μg/ ml) each week. I also grew A. thaliana in petri dishes (n=83) containing Murashige and Skoog (MS) medium, with a concentration of 4μg/ ml Ag-QDs or 4μg/ml CNTs. I measured carbon assimilation …

Novel Indices To Quantify Freeze Tolerance In Amphibians, Jolene R. Rearick

Biology ETDs

We propose Freeze Endurance (F_end) as a new measure of the ability of amphibians to tolerate internal freezing, allowing integration of time and temperature to describe each freeze event. Use of freeze endurance as a descriptor allows direct comparison between individuals, populations, and species, and may be scaled by body size, or other characteristics, to determine if abilities to survive freezing are significantly different between groups. Thermal limit examinations have long suffered from lack of comparability between publications due to differing endpoints, measurements, equipment, and organism availability, despite the value of information yielded by such studies to understanding …

Hearing On The Fly: The Effects Of Wing Position On Noctuid Moth Hearing, Shira D. Gordon, Elizabeth Klenschi, James F. C. Windmill

Dartmouth Scholarship

The ear of the noctuid moth has only two auditory neurons, A1 and A2, which function in detecting predatory bats. However, the noctuid's ears are located on the thorax behind the wings. Therefore, as these moths need to hear during flight, it was hypothesized that wing position may affect their hearing. The wing was fixed in three different positions: up, flat and down. An additional subset of animals was measured with freely moving wings. In order to negate any possible acoustic shadowing or diffractive effects, all wings were snipped, leaving the proximal-most portion and the wing hinge intact. Results revealed …

Identification Of Multiple Functional Receptors For Tyramine On An Insect Secretory Epithelium, Haiying Zhang, Edward M. Blumenthal

Biological Sciences Faculty Research and Publications

The biogenic amine tyramine (TA) regulates many aspects of invertebrate physiology and development. Although three TA receptor subtypes have been identified (TAR1-3), specific receptors have not been linked to physiological responses in native tissue. In the Malpighian (renal) tubule of Drosophila melanogaster, TA activates a transepithelial chloride conductance, resulting in diuresis and depolarization of the transepithelial potential. In the current work, mutation or RNAi-mediated knockdown in the stellate cells of the tubule of TAR2 (tyrR, CG7431) resulted in a dramatic reduction, but not elimination, of the TA-mediated depolarization. Mutation or knockdown of TAR3 (tyrRII, …

Winner's Curse Correction And Variable Thresholding Improve Performance Of Polygenic Risk Modeling Based On Genome-Wide Association Study Summary-Level Data, Jianxin Shi, Ju-Hyun Park, Jubao Duan, Sonja T. Berndt, Winton Moy, Kai Yu, Lei Song, William Wheeler, Xing Hua, Debra Silverman, Montserrat Garcia-Closas, Chao Agnes Hsiung, Jonine D. Figueroa, Victoria K. Cortessis, Nuria Malats, Margaret R. Karagas

Dartmouth Scholarship

Recent heritability analyses have indicated that genome-wide association studies (GWAS) have the potential to improve genetic risk prediction for complex diseases based on polygenic risk score (PRS), a simple modelling technique that can be implemented using summary-level data from the discovery samples. We herein propose modifications to improve the performance of PRS. We introduce threshold-dependent winner’s-curse adjustments for marginal association coefficients that are used to weight the single-nucleotide polymorphisms (SNPs) in PRS. Further, as a way to incorporate external functional/annotation knowledge that could identify subsets of SNPs highly enriched for associations, we propose variable thresholds for SNPs selection. We applied …

Examining The Combined Effects Of Dissolved Oxygen, Temperature, And Body Size On The Physiological Responses Of A Model Macrobenthic Polychaete Species, Capitella Teleta, Kelsey Burns Gillam

Dissertations

While the scientific community is in consensus that coastal systems are threatened by climate change, few climate change studies test the effects of more than one variable directly related to climate change. The dissolved oxygen (DO) levels of the ocean are currently subject to both global warming and eutrophication; 94% of all hypoxia zones are expected to experience >2°C increase by 2035. This dissertation aims to examine how a model organism responds to simultaneous thermal and DO stress involving four levels of DO (100%, 70%, 50%, and 20%) saturation and three temperatures (15°C, 20°C, and 25°C).

The polychaete, Capitella teleta …

The Roles Of Biotin In Candida Albicans Physiology, Nur Ras Aini Ahmad Hussin

School of Biological Sciences: Dissertations, Theses, and Student Research

Due to the increased number of immunocompromised patients, infections by Candida albicans have significantly increased in recent years. C. albicans transition from yeast to germ tubes is an essential factor for virulence. In this study we noted that Lee's medium, commonly used to induce filamentation, contained 500-fold more biotin than needed for growth. Thus, we investigated the effects of excess biotin on growth rate and filamentation by C. albicans in different media. At 37 °C, excess biotin (4 µM) enhanced germ tube formation (GTF) ca. 10-fold in both Lee's medium and a defined glucose proline medium, and ca. …

The Variation Of Productivity And Its Allocation Along A Tropical Elevation Gradient: A Whole Carbon Budget Perspective, Yadvinder Malhi, Cécile A. J. Girardin, Gregory R. Goldsmith, Christopher E. Doughty, Norma Salinas, Daniel B. Metcalfe, Walter Huaraca Huasco, Javier E. Silva-Espejo, Jhon Del Aguilla-Pasquell, Filio Farfán Amézquita, Luiz E.O.C. Aragão, Rossella Guerrieri, Françoise Yoko Ishida, Nur Bahar, William Farfan-Rios, Oliver L. Phillips, Patrick Meir, Miles Silman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

• Why do forest productivity and biomass decline with elevation? To address this question, research to date generally has focused on correlative approaches describing changes in woody growth and biomass with elevation.
  
  
• We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300 m elevation transect in Peru.
  
  
• Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy. The lack of trend in …

Development Of Vip-Sst Interneuron Associations In Mouse Neocortex And Entorhinal Cortex, Aayushi A. Mehta

Honors Scholar Theses

Cortical networks depend upon inhibition through the neurotransmitter GABA to control and coordinate specific spatiotemporal circuit patterns, underlying the exquisite complexity of neural signaling. Disinhibition, a form of inhibition where inhibitory neurons inhibit other inhibitory cells, further aids in amplifying local neural processing in a selective, organized manner. A subset of GABAergic interneurons, vasoactive intestinal peptide-expressing (VIP) cells, preferentially inhibit somatostatin interneurons, which provide inhibitory input onto pyramidal cells, thus creating an archetypal circuit illustrating disinhibition in the cortex. The aim of this anatomical study was to investigate variations in GABAergic VIP synapses onto somatostatin-expressing inhibitory interneurons in mice at …

Effects Of Rapid Ph And Salinity Change On The Physiology Of A Local Estuarine Fish Species, Fundulus Heteroclitus, Shauna Tietze

GS4 Student Scholars Symposium

Coastal Georgia offers a wide variety of unique aquatic environments, one of the most variable of these environments are salt marshes. Sapelo Island, Georgia, is a pristine environment that is home to many variable salt marshes. Throughout marshes, salinity ranges from freshwater to full strength sea water and acidity levels range from neutral (pH 7) to low pH (pH < 4.5). Fundulus heteroclitus (Atlantic killifish) is an example of an organism that has evolved coping strategies to withstand such a variable environment. Many laboratory studies have shown that F. heteroclitus exhibit a broad tolerance range of single stressors, however few have studied their ability to handle multiple stressors simultaneously. Our goal is to determine if exposure to low salinity and low pH combined is more stressful to F. heteroclitus than individual exposure to low salinity or low pH. To address this area of interest a laboratory experiment was designed. F. heteroclitus were captured from a site with neutral pH (6.8) and mid-range salinity (16 ppt) and held in the laboratory for one month at the same water conditions. The water conditions of the capture site represents similar conditions to where the fish were most commonly found on the island. Fish were then placed in tanks with four different water treatments; low salinity, low pH, low salinity and low pH combined, and a control and held at these conditions for one week. Six fish were sampled from each treatment group at 24 hours, 5 days, and 7 days post transfer. During sampling fish were euthanized, the gills were taken for gene expression analysis and the rest of the body was used for cortisol analysis. Changes in the mRNA expression levels of Cystic Fibrosis Transmembrane Conductance Regulator and Na /K -ATPase were compared between treatments using qRT-PCR analysis. These genes have been shown to play an important role in ion regulation in the gills by altering cell volume and ion movement in the sodium/potassium pump. Cortisol was also analyzed using an ELISA kit (Neogen) as a general stress response measure. I hypothesize that results from gene expression and cortisol analysis will show that F. heteroclitus challenged with low salinity and low pH combined experience a higher level of stress compared to fish challenged with only low salinity or low pH, exhibited by an increase in cortisol levels and increased expression of genes responsible for ion balance The information gained from this project will provide a better understanding of the stress this species exhibits due to rapid pH and salinity change. As well as, whether fish can rapidly adapt to changing conditions. Given the ubiquity of the common killifish and its importance in estuarine food webs, these data may provide insight into how we can manage and maintain diverse fish populations and support ecosystem functioning.

Factors Affecting The Immune System Of The Ornate Box Turtle (Errapene Ornata), Michelle W. Mcquinn, Abigail A. Neyer, Gwendolyn C. Bachman

UCARE: Research Products

While many studies have detailed the complex intricacies of the endothermic immune system, relatively little is known about the immune system of ectotherms--specifically, reptiles. In an attempt to gain more knowledge about the factors affecting reptilian immune function, ornate box turtles (Terrapene ornata) were subjected to chronic stress in the form of high ambient temperatures in a semi-natural environment. It was hypothesized that chronic stress would lead to elevated levels of corticosterone in the blood, which would, in turn, suppress immune activity. It was found that body temperature and body mass in particular were significantly affected by chronic heat stress. …

Cytoskeletal Dynamics: A View From The Membrane, Magdalena Bezanilla, Amy S. Gladfelter, David R. Kovar, Wei-Lih Lee

Dartmouth Scholarship

Many aspects of cytoskeletal assembly and dynamics can be recapitulated in vitro; yet, how the cytoskeleton integrates signals in vivo across cellular membranes is far less understood. Recent work has demonstrated that the membrane alone, or through membrane-associated proteins, can effect dynamic changes to the cytoskeleton, thereby impacting cell physiology. Having identified mechanistic links between membranes and the actin, microtubule, and septin cytoskeletons, these studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.

Effects Of Low Concentrations Of Carbon Nanotubes On Growth And Gas Exchange In Arabidopsis Thaliana, Rajeeva Voleti

Graduate Theses/Dissertations

The effect of pure single-walled carbon nanotubes (SWCNTs) on plant growth and gas exchange was investigated in Arabidopsis thaliana. To date there has been no research on the effects of SWCNTs on whole plant physiology. A. thaliana seeds were directly grown in growth medium containing SWCNTs concentrations of 24.93micrograms/ml and 53.55 micrograms/ml. control plants were grown in media containing distilled water. I determined growth by measuring dry mass of plants. I determined gas exchange by measuring photosynthetic rates, stomatal conductance, transpiration rates, and water use efficiency. I also examined the following physiological mechanisms that would limit plant growth: ATP and …

Prooxidant Effects Of Melatonin: A Brief Review, Malwina S. Munik, Cem Ekmekçi̇oğlu

Turkish Journal of Biology

Melatonin acts classically through the widely expressed G protein-coupled membrane receptors MT1 and MT2, respectively. The functional role of the MT receptors is not fully clear with multiple effects, such as effects on the circadian, reproductive, immune, cardiovascular, and intestinal systems, being suggested. In addition to receptor-mediated effects, melatonin also acts as a potent antioxidant and it is quite evident that melatonin and its metabolites efficiently reduce oxidative damage to proteins, lipids, and DNA and also exert protective effects on mitochondria. The potent antioxidant activity of melatonin stems from various complex mechanisms, including direct scavenging of radicals, stimulation of antioxidant …

Human Anatomy And Physiology Preparatory Course (1st Edition), Carlos Liachovitzky

Open Educational Resources

The overall purpose of this preparatory course textbook is to help students familiarize with some terms and some basic concepts they will find later in the Human Anatomy and Physiology I course.

The organization and functioning of the human organism generally is discussed in terms of different levels of increasing complexity, from the smallest building blocks to the entire body. This Anatomy and Physiology preparatory course covers the foundations on the chemical level, and a basic introduction to cellular level, organ level, and organ system levels. There is also an introduction to homeostasis at the beginning.

Understanding The Physiological Effects Of Suspended Material On Rainbow Trout (Oncorhynchus Mykiss), Tyler J. Weinhardt

Theses and Dissertations (Comprehensive)

The effect of global warming on northern environments is becoming increasingly evident. Melting of underlying permafrost is associated with widespread impacts in these environments. The loss of permafrost results in a destabilizing of underlying sedimentary layers resulting in thermokarst slumping. When this occurs on a large scale (mega-slumping) soil material becomes mobilized and is carried into local streams and rivers. The purpose of this study is to examine the sub-lethal physiological effects that suspended material has on rainbow trout (Oncorhynchus mykiss) in the context of the Peel River Plateau. Juvenile rainbow trout were exposed (following Environment Canada exposure …

Natural Selection On Thermal Performance In A Novel Thermal Environment, Michael L. Logan, Robert M. Cox, Ryan Calsbeek

Dartmouth Scholarship

Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation …

The Use Of Stable Isotopes To Determine The Physiology And Ecology Of Reptiles, Jessica Makin, Kent Hatch

Journal of Undergraduate Research

Stable isotope research is becoming more widely used in physiological ecology. Atoms of the same atomic number but different atomic weights are called isotopes. Nitrogen (N) has two isotopes, 14N and 15N, with the latter being the heavier isotope. The assumption is that 14N is excreted at a higher rate than 15N. It is also thought that this should cause an increase in 15N of the protein tissues and preferential excretion of 14N of an animal when the animal is in the process of breaking down proteins.

Dirigent Domain-Containing Protein Is Part Of The Machinery Required For Formation Of The Lignin-Based Casparian Strip In The Root, Prashant S. Hosmani, Takehiro Kamiya, John Danku, Sadaf Naseer, Niko Geldner, Mary Lou Guerinot, David Salt

Dartmouth Scholarship

The endodermis acts as a "second skin" in plant roots by providing the cellular control necessary for the selective entry of water and solutes into the vascular system. To enable such control, Casparian strips span the cell wall of adjacent endodermal cells to form a tight junction that blocks extracellular diffusion across the endodermis. This junction is composed of lignin that is polymerized by oxidative coupling of monolignols through the action of a NADPH oxidase and peroxidases. Casparian strip domain proteins (CASPs) correctly position this biosynthetic machinery by forming a protein scaffold in the plasma membrane at the site where …

Septin Phosphorylation And Coiled-Coil Domains Function In Cell And Septin Ring Morphology In The Filamentous Fungus Ashbya Gossypii, Rebecca A. Meseroll, Patricia Occhipinti, Amy S. Gladfelter

Dartmouth Scholarship

Septins are a class of GTP-binding proteins conserved throughout many eukaryotes. Individual septin subunits associate with one another and assemble into heteromeric complexes that form filaments and higher-order structures in vivo. The mechanisms underlying the assembly and maintenance of higher-order structures in cells remain poorly understood. Septins in several organisms have been shown to be phosphorylated, although precisely how septin phosphorylation may be contributing to the formation of high-order septin structures is unknown. Four of the five septins expressed in the filamentous fungus, Ashbya gossypii, are phosphorylated, and we demonstrate here the diverse roles of these phosphorylation sites …