A Proposed Mechanism For Nitrogen Acquisition By Grass Seedlings Through Oxidation Of Symbiotic Bacteria, James F. White Jr., Holly Crawford, Mónica S. Torres, Robert Mattera, Ivelisse Irizarry, Marshall Bergen

All Faculty Scholarship for the College of the Sciences

In this paper we propose and provide evidence for a mechanism, oxidative nitrogen scavenging (ONS), whereby seedlings of some grass species may extract nitrogen from symbiotic diazotrophic bacteria through oxidation by plant-secreted reactive oxygen species (ROS). Experiments on this proposed mechanism employ tall fescue (Festuca arundinaceae) seedlings to elucidate features of the oxidative mechanism. We employed 15N₂ gas assimilation experiments to demonstrate nitrogen fixation, direct microscopic visualization of bacteria on seedling surfaces to visualize the bacterial oxidation process, reactive oxygen probes to test for the presence of H₂O₂ and cultural experiments to assess conditions …

Characterization Of Biofilm Formation By Borrelia Burgdorferi In Vitro, Eva Sapi, Scott L. Bastian, Cedric L. Mpoy, Shernea Scott, Amy Rattelle, Namrata Pabbati, Akhila Poruri, Divya Burugu, Priyanka A. Theophilus, Truc V. Pham, Akshita Datar, Navroop K. Dhaliwal, Alan Macdonald, Michael J. Rossi, Saion K. Sinha, David F. Luecke

Biology and Environmental Science Faculty Publications

Borrelia burgdorferi, the causative agent of Lyme disease, has long been known to be capable of forming aggregates and colonies. It was recently demonstrated that Borrelia burgdorferi aggregate formation dramatically changes the in vitro response to hostile environments by this pathogen. In this study, we investigated the hypothesis that these aggregates are indeed biofilms, structures whose resistance to unfavorable conditions are well documented. We studied Borrelia burgdorferi for several known hallmark features of biofilm, including structural rearrangements in the aggregates, variations in development on various substrate matrices and secretion of a protective extracellular polymeric substance (EPS) matrix using several modes …

The Importance Of Host Plant Limitation For Caterpillars Of An Arctiid Moth (Platyprepia Virginalis) Varies Spatially, Richard Karban, Patrick Grof-Tisza, John L. Maron, Marcel Holyoak

Biological Sciences Faculty Publications

Spatial dynamic theories such as source–sink models frequently describe habitat-specific demographies, yet there are surprisingly few field studies that have examined how and why interacting species vary in their dynamics across multiple habitat types. We studied the spatial pattern of interaction between a chewing herbivore and its primary larval host plant in two habitat types. We found that the interaction between an arctiid caterpillar (Platyprepia virginalis) and its host (Lupinus arboreus) differed in wet vs. upland dry habitats, as did yearly population dynamics for the caterpillar. In upland sites, there was a strong positive relationship between …

Spatial And Temporal Immune Response In House Flies In Response To Ingestion Of Bacillus Cereus And Eschericha Coli 0157-H7, Adam Fleming

College of Graduate Studies: Theses & Dissertations

House flies (Musca domestica L.) feed and breed on septic substrates, putting them in direct contact with a multitude of disease causing agents and can act as a bridge for those agents to humans. The house fly has previously been shown to carry many different species of bacteria that are pathogenic. Escherichia coli O157:H7 is a pathogenic enterohemorrhagic serotype of E. coli that can be vectored by the house fly. Bacillus cereus is a foodborne pathogen that has also been isolated from the house fly in previous studies. To examine vector potential for these pathogens, house flies were fed green …

Predation Risk And Colony Structure In The Pea Aphid, Acyrthosiphon Pisum, Carl Nicolas Keiser

College of Graduate Studies: Theses & Dissertations

Many organisms live in transient or permanent aggregations to reduce individual predation risk. Hamilton's "Selfish Herd" theory states that an individual should assume a central position within a group to decrease individual predation risk relative to that of its neighbors (i.e., individuals should be selfish). This theory, however, cannot predict the spatial distribution of individuals within clonal aggregations, that is, when individuals are genetically identical (the "evolutionary self"). As aphids (small, herbivorous insects) are parthenogenetic, emit alarm signals, and have high levels of phenotypic plasticity to cope with environmental stressors like predation risk, they are a model organism for investigating …

West Nile Virus Seroreversion And The Influence Of Herd Immunity On Disease Risk In A Long-Term Study Of Free-Ranging Birds, Eileen M. Mckee

All Student Theses and Dissertations

The transmission and amplification of West Nile virus (WNV) is driven by the number of susceptible avian hosts. The quantity of susceptible hosts is determined by 1) recruitment of juvenile birds during the breeding season, 2) adult birds previously unexposed to WNV, and 3) adult birds with waning antibody titers. Although rarely tested, avian herd immunity and seroreversion could have a direct impact on Culex infection rate, a proxy for the reproductive number of WNV. In this study, we utilized data from a seven year study investigating WNV transmission ecology in suburban Chicago, Illinois. We tested the hypothesis that herd …

Behavioral And Physiological Female Responses To Male Sex Ratio Bias In A Pond-Breeding Amphibian, Kristine L. Grayson, Stephen P. De Lisle, Jerrah E. Jackson, Samuel J. Black, Erica J. Crespi

Biology Faculty Publications

Introduction: The phenomenon of sexual conflict has been well documented, and in populations with biased operational sex ratios the consequences for the rarer sex can be severe. Females are typically a limited resource and males often evolve aggressive mating behaviors, which can improve individual fitness for the male while negatively impacting female condition and fitness. In response, females can adjust their behavior to minimize exposure to aggressive mating tactics or minimize the costs of mating harassment. While male-male competition is common in amphibian mating systems, little is known about the consequences or responses of females. The red-spotted newt (Notophthalmus …

Arabidopsis Bhlh100 And Bhlh101 Control Iron Homeostasis Via A Fit-Independent Pathway, Alicia B. Sivitz, Victor Hermand, Catherine Curie, Grégory Vert

Dartmouth Scholarship

Iron deficiency induces a complex set of responses in plants, including developmental and physiological changes, to increase iron uptake from soil. In Arabidopsis, many transporters involved in the absorption and distribution of iron have been identified over the past decade. However, little is known about the signaling pathways and networks driving the various responses to low iron. Only the basic helix–loop–helix (bHLH) transcription factor FIT has been shown to control the expression of the root iron uptake machinery genes FRO2 and IRT1. Here, we characterize the biological role of two other iron-regulated transcription factors, bHLH100 and bHLH101, in iron homeostasis. …

Resource‐Based Habitat Associations In A Neotropical Liana Community, James W. Dalling, Stefan A. Schnitzer, Claire Baldeck, Kyle E. Harms, Robert John, Scott A. Mangan, Elena Lobo, Joseph B. Yavitt, Stephen P. Hubbell

Biological Sciences Faculty Research and Publications

Summary

1. Lianas are a conspicuous element of many tropical forests, accounting for up to 40% of woody stem density and 20% of species richness in seasonal forests. However, lianas have seldom been surveyed at sufficiently large spatial scales to allow an assessment of the importance of habitat variables in structuring liana communities.

2. We compare the association patterns of 82 liana species and an equivalent sample of tree species on the 50 ha Forest Dynamics Project plot on Barro Colorado Island, Panama, with topographic habitat variables (high and low plateau, slope, swamp and streamside), and thirteen mapped soil chemical …

Non-Photoperiodic Regulation Of Reproductive Physiology In The Flexibly Breeding Pine Siskin (Spinus Pinus), Heather E. Watts, Thomas P. Hahn

Biology Faculty Works

In order to time reproduction to coincide with favorable conditions, animals use environmental cues to up- and down-regulate the reproductive axis appropriately. Although photoperiodic cues are one of the best studied of such environmental cues, animals also attend to others such as temperature, food availability, rainfall and social cues. Such non-photic cues are expected to be particularly important for tropical species and temperate-zone species that exhibit flexible or opportunistic breeding schedules. In this study, we investigate the use of non-photic cues, specifically food availability and social cues, to time the initiation of reproductive development in the pine siskin (Spinus …

Competitive Abilities In Experimental Microcosms Are Accurately Predicted By A Demographic Index For R*, Ebony G. Murrell, Steven A. Juliano

Faculty Publications – Biological Sciences

Resource competition theory predicts that R*, the equilibrium resource amount yielding zero growth of a consumer population, should predict species' competitive abilities for that resource. This concept has been supported for unicellular organisms, but has not been well-tested for metazoans, probably due to the difficulty of raising experimental populations to equilibrium and measuring population growth rates for species with long or complex life cycles. We developed an index (R-index) of R* based on demography of one insect cohort, growing from egg to adult in a non-equilibrium setting, and tested whether R-index yielded accurate predictions of competitive abilities using mosquitoes as …

Plant Calcium Content: Ready To Remodel, Jian Yang, Tracy Punshon, Mary Lou Guerinot, Kendal D. Hirschi

Dartmouth Scholarship

By identifying the relationship between calcium location in the plant cell and nutrient bioavailability, the plant characteristics leading to maximal calcium absorption by humans can be identified. Knowledge of plant cellular and molecular targets controlling calcium location in plants is emerging. These insights should allow for better strategies for increasing the nutritional content of foods. In particular, the use of preparation-free elemental imaging technologies such as synchrotron X-ray fluorescence (SXRF) microscopy in plant biology may allow researchers to understand the relationship between subcellular location and nutrient bioavailability. These approaches may lead to better strategies for altering the location of calcium …

A Ranksum Statistics Based Framework To Decipher Transcription Regulation, Iuan-Bor Chen

Arts & Sciences Graduate Student Theses and Dissertations

The unbiased generation of specific and meaningful hypotheses from the deluge of data generated by modern genomic methods remains a challenge. These datasets require increasing level of expertise to analyze fully, and are often underutilized even in the originating lab. It would be desirable to have a computational strategy that is easy to implement, robust against outliers and missing data, and broadly applicable to diverse experimental designs. In this dissertation, I present a set of ranksum statistics-based analytical methods as a framework to extract testable hypotheses from large and complex datasets. To illustrate its utility, this framework was applied to …

Ocean Acidification: Understanding The Coastal Carbon Pump In A High Co2 World, Rachel Cooper

Theses and Dissertations

Since the 1800s, carbon dioxide emissions due to human activities have contributed significantly to the amount of carbon in the atmosphere. Approximately a third of this carbon is absorbed by the ocean, through air-sea fluxes at the ocean surface (Sabine, 2004). Increased CO2 has changed the carbon chemistry of the ocean and hence the pH. pH is expected to drop by 0.4 by the year 2100. It is unclear how this lower pH will affect carbon cycling and sequestration with respect to the biological carbon pump. Most studies have focused on open ocean phytoplankton or bacterial communities in large, stationary …

Characterization Of A Vibrio Fischeri Aminopeptidase And Evidence For Its Influence On An Early Stage Of Squid Colonization, Pat M. Fidopiastis, Bethany A. Rader, David G. Gerling, Nestor A. Gutierrez, Katherine H. Watkins, Michelle West Frey, Spencer V. Nyholm, Cheryl A. Whistler

Biological Sciences

Vibrio fischeri cells are the sole colonists of a specialized light organ in the mantle cavity of the sepiolid squid Euprymna scolopes. The process begins when the bacteria aggregate in mucus secretions outside the light organ. The cells eventually leave the aggregate, enter the light organ, and encounter a rich supply of peptides. The need to dissociate from mucus and presumably utilize peptides led us to hypothesize that protease activity is integral to the colonization process. Protease activity associated with whole cells of Vibrio fischeri strain ES114 was identified as the product of a putative cell membrane-associated aminopeptidase (PepN). To …

How Do Host Sex And Reproductive State Affect Host Preference And Feeding Duration Of Ticks?, Nicholas B. Pollock, Larisa K. Vredevoe, Emily N. Taylor

Biological Sciences

Parasitism is one of the most notable forms of symbiosis in the biological world, with nearly all organisms hosting parasites. In many vertebrates, males have higher ectoparasite burdens than females, especially when testosterone concentrations are elevated. Furthermore, reproductive females may have higher ectoparasite burdens than non-reproductive females. It is possible that testosterone-stimulated behaviors in males and offspring investment by females incur energetic costs that inhibit immune function. If questing ticks can sense host sex or reproductive condition prior to attachment, they could potentially choose hosts with the poorest immune function, thereby leading to improved feeding success and decreased feeding duration. …

Direct Effects Of Glucose And Fructose On Proliferation And Activation Of Jurkat T-Lymphocytes, C.J. Urso

Theses, Dissertations and Culminating Projects

High-fructose com syrup has been used with increasing commonality in recent decades. During this interval there is strong evidence of increased occurrence of autoimmune disease. We hypothesized that increased glucose and fructose concentration activates T-cells. Using Jurkat T-cells as a model, we found that increased glucose and fructose concentration decreased Jurkat T-cell proliferation and death rates at pH 7.4 while at pH 7.2 the above effects did not reach significance. Cells in high glucose and fructose concentration formed clusters that were unbreakable by standard trituration techniques suggesting the expression of high-affinity adhesion molecules characteristic of T-cell activation; this effect was …

Nutritional Content Of Rhinoceros Auklet (Cerorhinca Monocerata) Bill Loads, Dustin Taylor, Ron Heintz

STAR Program Research Presentations

Nutritional Content of Rhinoceros Auklet Bill Loads

Dustin E Taylor

Abstract

An adult Rhinoceros Auklet (Cerorhinca monocerata) can only catch and carry a limited amount of prey to their nestlings after a foraging trip. The auklets therefore must maximize their efficiency by bringing back the most proportionally nutritious prey items to their nestlings. The prey carried back to the nesting sites (known as a ‘bill load’) can contain whole fish, as well as parts, most commonly fish heads. This study is aimed to determine whether returning with just heads to the nestlings was proportionally more nutritious than bringing …

Serratia Marcescens: The Miracle Bacillus, Alan L. Gillen, Rebekah Gibbs

Faculty Publications and Presentations

The objectives of this article are to explain the mysterious appearance of crimson-colored bacteria on food and communion bread/wafers, over the centuries, as well as to describe the biological basis

Condition And Brightness Of Structural Blue-Green: Motmot Tail-Racket Brightness Is Related To Speed Of Feather Growth In Males, But Not In Females, Troy G. Murphy, Tiffany T. Pham

Biology Faculty Research

Coloration plays an important role in sexual and social communication, and in many avian species both males and females maintain elaborate colours. Recent research has provided strong support for the hypothesis that elaborate female traits can be maintained by sexual or social selection; however, most research on female ornamentation has focused on pigment-based colours, and less is known about how structural colours are maintained. Both sexes of the turquoise-browed motmot (Eumomota superciliosa) have a blue-green racket-tipped tail, and it remains unknown if tail coloration serves as a sexual or social signal in one or both sexes. Here, we …

Dietary Lipid Saturation Influences Environmental Temperature Preference But Not Resting Metabolic Rate In The Djungarian Hamster (Phodopus Sungorus), Ryan Pannorfi , '04, Barry Michael Zee , '08, I. Vatnick, N. Berner, Sara Hiebert Burch

Biology Faculty Works

Heterothermic rodents increase self-selection of diets rich in polyunsaturated fatty acids (PUFAs) when exposed to cold, short days, or short-day melatonin profiles, and Djungarian hamsters (Phodopus sungorus) do so in long days in response to cold exposure alone. To determine whether Djungarian hamsters are also capable of selecting a thermal environment in response to dietary lipid composition, continuously normothermic hamsters were fed either a PUF-rich diet or a diet rich in saturated fatty acids (SFAs) for 6-10 wk and given a choice of thermal environments. As predicted, SF-fed hamsters were more likely than PUFA-fed hamsters to occupy the single heated …

The Contribution Of Young-Of-Year Fishes To Aquatic Food Web Dynamics In An Arid-Land River System (Rio Grande, New Mexico), Corey Anne Krabbenhoft

Biology ETDs

1. Larval fishes have a rich history in ichthyological research. However, relatively little attention has been given to the role of young-of-year (YOY) fishes in ecosystem processes. Despite difficulties of sampling and identifying these small fishes, YOY may serve an important role in the dynamics of some aquatic communities. The specific role of YOY fishes in aquatic, desert food webs remains largely uncharacterized.

2. We hypothesize that YOY fishes may control abundance and community composition of lower trophic levels (i.e., aquatic invertebrates) because they are numerically dominant predators during the growing season. The goal of this study is to determine …

Effects Of Global Change On Savanna Grassland Ecosystems, Sally Elizabeth Koerner

Biology ETDs

Humans are altering the environment locally and globally through climate and land use change. Global temperature is increasing, precipitation patterns are becoming more variable, disturbance regimes are being altered, and ecosystems are being simplified as multi-species communities are replaced by monocultures of crops or livestock. Grasslands, which cover approximately a third of the terrestrial lands, are ecologically and economically significant, thus their responses to environmental change will have dramatic consequences for global patterns of productivity, biodiversity, and food production. This dissertation research investigates how the three main drivers of mesic grassland ecosystems — precipitation, grazing, and fire - interact to …

Linking Environment To Ecology In Arid Land Consumers: Two Case Studies, Ian White Murray

Biology ETDs

The physical environment has a profound influence over many aspects of animal ecology, such as governing the pace and timing of phenology and the patterns of activity across space and time. In extreme habitats such as deserts, the most important components of the physical environment are precipitation and temperature. Not only do these vary temporally and spatially, but this variation may influence the life history and ecology of species. My research examines how variance in temperature and precipitation influences the ecology of two species of desert dwelling consumers (desert woodrats and desert tortoises) over differing temporal scales. In Chapter 1, …

Effects Of Translocation And Climatic Events On The Population Genetic Structure Of Black Bears In New Mexico, Frederic S. Winslow

Biology ETDs

Population structure of the American black bear (Ursus americanus) in New Mexico has been shaped by anthropogenic and natural forces. Black bears occur in habitat islands throughout New Mexico with natural movement among islands influenced by periodic drought, resource limitations and dispersal. Both natural movement and human mediated translocations primarily involve male black bears because of their tendency to move farther distances and more frequent conflict with human dominated landscapes than females. Using DNA microsatellite analysis to investigate the degree of differentiation between different population segments (Fst =0.025 across genetic loci, range = 0.018-0.032) we determined that black bear populations …

The Likelihood Of Extinction Of Iconic And Dominant Herbivores And Detritivores Of Coral Reefs: The Parrotfishes And Surgeonfishes, Mia T. Comeros-Raynal, John H. Choat, Beth A. Polidoro, Kendall D. Clements, Rene Abesamis, Matthew T. Craig, Muhammad E. Lazuardi, Jennifer Mcilwain, Andreas Muljadi, Robert F. Myers, Cleto L. Nanola Jr., Shinta Pardede, Luiz A. Rocha, Barry Russell, Jonnell C. Sanciangco, Brian Stockwell, Heather Harwell, Kent E. Carpenter

Biological Sciences Faculty Publications

Parrotfishes and surgeonfishes perform important functional roles in the dynamics of coral reef systems. This is a consequence of their varied feeding behaviors ranging from targeted consumption of living plant material (primarily surgeonfishes) to feeding on detrital aggregates that are either scraped from the reef surface or excavated from the deeper reef substratum (primarily parrotfishes). Increased fishing pressure and widespread habitat destruction have led to population declines for several species of these two groups. Species-specific data on global distribution, population status, life history characteristics, and major threats were compiled for each of the 179 known species of parrotfishes and surgeonfishes …

Availability And Quality Of Vegetation Affects Reproduction Of The Gopher Tortoise (Gopherus Polyphemus) In Improved Pastures, Anna Louise Hathaway

USF Tampa Graduate Theses and Dissertations

As part of a state-funded Gopher Tortoise (Gopherus polyphemus Daudin) translocation project, I monitored actively grazed improved pastures to determine if they could serve as suitable recipient sites for the threatened Gopher Tortoise displaced by human development. For cattle ranches to be considered suitable recipient sites females must be able to acquire sufficient energy to produce a clutch of viable eggs, and sufficiently high quality vegetation must be available to support juvenile recruitment into the population. Vegetation surveys were conducted to determine the composition and percent cover of plant species, especially those containing high amounts of nutrients, specifically nitrogen. Resident …

The Role Of A And B Vitamins During Orofacial Development Of Xenopus Laevis, Allyson Kennedy

Theses and Dissertations

Orofacial anomalies make up about a third of the 120,000 birth defects each year in the United States. Children born with these abnormalities must undergo immense physical and emotional strain in order to correct the defects. In fact, about $697 million is spent every year surgically treating children with cleft lip and/or cleft palate (2011). In countries where surgery is not an option, this abnormality causes immense difficulties in eating, hearing, speech, and psychosocial development. The causes of cleft lip/palate are extremely complex. Genetics play a role in the anomaly; however, 95% of cleft palate cases are non-syndromic and likely …

Traversing Swanton Road, 9th Ed., James A. West

Academic, Government & Associated Organizational Research Resources

Situated at the northwest end of Santa Cruz County and occupying circa 30 square miles of sharply contrasted terrain, the Scott Creek Watershed concentrates within its geomorphological boundaries, at least 10-12% of California's flora, both native and introduced. Paradoxically, the use/abuse that the watershed has sustained over the past 140+ years, has not necessarily diminished the biodiversity and perhaps parallels the naturally disruptive but biologically energizing processes (fire, flooding, landslides and erosion), which have also been historically documented for the area for +60 years. This is an early edition of an extensive document by James A. West. Please visit the …

Bacteriophages Phi Mr299-2 And Phi Nh-4 Can Eliminate Pseudomonas Aeruginosa In The Murine Lung And On Cystic Fibrosis Lung Airway Cells, Aidan Coffey, Et. Al.

Department of Biological Sciences Publications

Pseudomonas aeruginosa is a common cause of infection in the lungs of patients with cystic fibrosis (CF). In addition, biofilm formation and antibiotic resistance of Pseudomonas are major problems that can complicate antibiotic therapy. We evaluated the efficacy of using bacteriophages to kill the pathogen in both biofilms and in the murine lung. We isolated and characterized two phages from a local wastewater treatment plant, a myovirus (ϕNH-4) and a podovirus (ϕMR299-2). Both phages were active against clinical isolates of P. aeruginosa. Together, the two phages killed all 9 clinical isolate strains tested, including both mucoid and nonmucoid strains. An …