Immunology and Infectious Disease Commons^™

Parasites Versus Predation: The Role Of Chronic And Acute Parasite Exposure In Infection Risk And Anti-Predator Behavior, Delaney Farrell

All HCAS Student Capstones, Theses, and Dissertations

Parasites with complex, multi-host lifecycles often engage in host behavior manipulation to increase transmission between successive hosts. In intermediate fish hosts, previous research has measured increased frequency of conspicuous behaviors, decreased swimming performance, and reduced antipredator behavior, which would collectively increase the fish’s risk of predation. In ecosystems where this type of parasite increased trophic transmission (PITT) occurs, parasites can play a substantial role in food webs. In this study, I investigate how chronic versus acute exposure to the trematode Euhaplorchis sp. A. affects the antipredator behavior of the Gulf killifish Fundulus grandis. Using a fully crossed design, I …

Investigation Of Orthohantavirus Genetics In Rodent Reservoirs And Clinical Samples, Samuel Melvin Goodfellow

Biomedical Sciences ETDs

Orthohantaviruses are negative-sense, single stranded RNA viruses with trisegmented genomes that can cause severe disease in humans and are carried by several host reservoirs throughout the world. In the United States, Sin Nombre orthohantavirus (SNV) is the primary cause of hantavirus cardiopulmonary syndrome (HCPS) with a fatality rate of ~36% and the highest cases occuring in the southwest region. The primary SNV host reservoir is thought to be the western deer mouse, Peromyscus maniculatus, however it has been shown that other rodents can carry different orthohantaviruses. We designed a pan-orthohantavirus detection tool to survey several small mammal populations throughout New …

Du Undergraduate Showcase: Research, Scholarship, And Creative Works, Caitlyn Aldersea, Justin Bravo, Sam Allen, Anna Block, Connor Block, Emma Buechler, Maria De Los Angeles Bustillos, Arianna Carlson, William Christensen, Olivia Kachulis, Noah Craver, Kate Dillon, Muskan Fatima, Angel Fernandes, Emma Finch, Colleen Cassidy, Amy Fishman, Andrea Francis, Stacia Fritz, Simran Gill, Emma Gries, Rylie Hansen, Shannon Powers, Jacqueline Martinez, Zachary Harker, Ashley Hasty, Mykaela Tanino-Springsteen, Kathleen Hopps, Adelaide Kerenick, Colin Kleckner, Ci Koehring, Elijah Kruger, Braden Krumholz, Maddie Leake, Lyneé Alves, Seraphina Loukas, Yatzari Lozano Vazquez, Haley Maki, Emily Martinez, Sierra Mckinney, Audrey Mitchell, Kipling Newman, Audrey Ng, Megan Lucyshyn, Andrew Nguyen, Stevie Ostman, Casandra Pearson, Alexandra Penney, Julia Gielczynski, Tyler Ball, Anna Rini, Christina Rorres, Simon Ruland, Helayna Schafer, Emma Sellers, Sarah Schuller, Claire Shaver, Kevin Summers, Isabella Shaw, Madison Sinar, Claudia Pena, Apshara Siwakoti, Carter Sorensen, Madi Sousa, Anna Sparling, Alexandra Revier, Brandon Thierry, Dylan Tyree, Maggie Williams, Lauren Wols

DU Undergraduate Research Journal Archive

DU Undergraduate Showcase: Research, Scholarship, and Creative Works

Effects Of Maternal Disease History On Provisioning, Brooding, And Offspring Outcomes, Sakura Roberts

Biological Sciences Undergraduate Honors Theses

Disease within a population has the ability to shape the development, evolution, and general performance of a species. Pathogen exposure to hosts can influence their physiology and behavioral patterns to further shape offspring immunity. Parental conditions experienced by offspring during early development can benefit survival and fitness (e.g. increasing provisioning rates), as well as help deter against similar diseases experienced by parents. By testing if parental behavior changes can better prepare offspring outcomes for disease exposure, such as disease severity or duration of infection, we can see the beneficial impacts it has on disease dynamics and host-pathogen processes. Incubation temperature, …

Does Stress Physiology Mediate Disease Resistance In The Arizona Tiger Salamander (Ambystoma Mavortium Nebulosum)?, Megan Zerger

2023 Midwest Ecology & Evolution Conference

Amphibian biodiversity has greatly diminished in recent years due to disease. Panzootic pathogenic fungi Batrachochytrium dendrobatidis (Bd) causes the deadly disease chytridiomycosis (chytrid), a primary driver of catastrophic global amphibian declines and extinctions. The pathogenesis of chytrid is still unclear, as certain species and individuals within a species are differentially affected. Susceptibility and mortality of Bd are influenced by prolonged chronic stress. Prolonged glucocorticoid activity deleteriously affects many of the same physiological processes as Bd infections, and corticosterone is the primary glucocorticoid released by amphibians in response to stress. Thus, the objective of our study is to assess …

Spatiotemporal Patterns Of Ticks And Tick-Borne Disease Dynamics At Neon Sites Across A Sub-Continental Scale., Ana Sofia Rivera

2023 Midwest Ecology & Evolution Conference

At local scales, dynamics of ticks and tick-borne diseases such as Lyme disease are driven by resource pulses, such as mast seeding in forest trees, that creates increases in tick hosts. Tick-borne diseases in humans have nearly doubled between 1940 and 2004 and understanding the dynamics of infectious diseases has long been of interest for ecologists. The family Ixodidae is the most capable of transmitting pathogens to humans and tick-borne diseases are the most common vector of illness in the United States. The objective of this research is to characterize the spatiotemporal dynamics of ticks and tick-borne diseases, which may …

Impact Of The Dimethyl Sulfoxide Reductase Superfamily On The Evolution Of Biogeochemical Cycles, Michael Wells, Minjae Kim, Denise M. Akob, Partha Basu, John F. Stolz

UK CARES Faculty Publications

The dimethyl sulfoxide reductase (or MopB) family is a diverse assemblage of enzymes found throughout Bacteria and Archaea. Many of these enzymes are believed to have been present in the last universal common ancestor (LUCA) of all cellular lineages. However, gaps in knowledge remain about how MopB enzymes evolved and how this diversification of functions impacted global biogeochemical cycles through geologic time. In this study, we perform maximum likelihood phylogenetic analyses on manually curated comparative genomic and metagenomic data sets containing over 47,000 distinct MopB homologs. We demonstrate that these enzymes constitute a catalytically and mechanistically diverse superfamily defined not …

The Future Of Pandemics: Land Use Controls As Means Of Preventing Zoonotic Disease, Bailey Andree

Pace International Law Review

Zoonotic diseases are increasing in frequency as climate change worsens around the world, with the recent COVID-19 pandemic highlighting the inadequate mechanisms in place to counteract disease spread. This article reviews various zoonotic diseases and their patterns of spread, highlighting land use change as the key driver of disease to demonstrate the need for legal intervention. International land use law is a little-developed subsect of environmental law that holds the key to combating this disease spread, and this article proposes solutions through this legal lens. Land use techniques which may be used to combat disease spread include conservation laws, setback …

A Dynamical System Model Of Dengue Transmission For Rio De Janeiro, Brazil, Gregory Schmidt, Benjamin Whipple, Vinodh Chellamuthu, Xiaoxia Xie

Spora: A Journal of Biomathematics

The dengue virus is a serious concern in many parts of the world, including Brazil. As data indicates, a prominent vector for dengue is the mosquito Aedes aegypti. By using the dengue incidence records from the Brazilian SINAN database, we estimate the population of A. aegypti within the city of Rio de Janeiro. Using historical climate data for Rio de Janeiro and the computed population estimates, we extend an existing model for the population dynamics of mosquitoes to incorporate precipitation in aquatic stages of development for A. aegypti.

Proposing An Rna Interference (Rnai)-Based Treatment For Human Immunodeficiency Virus (Hiv) By Analyzing The Post-Transcriptional Gene Targeting Of Sars-Cov-2, Hepatitis C Virus, And A549 Lung Cancer Cells, Arjun Jagdeesh

UROP Posters

Human Immunodeficiency Virus (HIV) is a retrovirus that infects CD4+ T cell lymphocytes in humans, leading to the development of Acquired Immunodeficiency Syndrome (AIDS) if left untreated. While current treatment methods, including antiretroviral combination treatments, effectively limit HIV replication, HIV can evade these treatments due to its high mutation rate. Long-term antiretroviral treatment can also be toxic to patients, meaning patients would benefit from a new mechanism of HIV treatment. RNA interference (RNAi) is an antiviral pathway found in mammals, plants, and insects that involves a small-interfering RNA that is incorporated into a protein complex called the RNA-induced Silencing Complex …

Intestinal Parasite Infection In Tibetan Macaques (Macac Thebetana) In Eastern China, Miarisoa Ramilison

All Master's Theses

Grooming is one of the crucial social behaviors of primate species that functions to remove parasites and maintain social bonds. Although, much data exists to support the idea that grooming is essential in forming and sustaining social bonds among individuals, there is a lack of information about the extent to which it removes ectoparasites or contributes to the spread of internal parasites. To fill this gap in the literature, we investigated the relationship between social contact behavior including grooming and intestinal parasite infection in Tibetan macaques (Macaca thibetana). This species lives at Mt. Huangshan in China. We used …

Intercontinental Comparisons Of Subterranean Host-Parasite Communities Using Bipartite Network Analyses, Altangerel Tsogtsaikhan Dursahinhan, Sebastian Botero-Cañola, Scott L. Gardner

Scott L. Gardner Publications

Rodents living in a subterranean ecotope face a unique combination of evolutionary and ecological pressures and while host species evolution may be driven by the selective pressure from the parasites they harbour, the parasites may be responding to the selective pressures of the host. Here we obtained all available subterranean rodent host-parasite records from the literature and integrated these data by utilizing a bipartite network analysis to determine multiple critical parameters to quantify and measure the structure and interactions of the organisms present in host-parasite communities. A total of 163 species of subterranean rodent hosts, 174 parasite species, and 282 …

The Use Of A Habitat Quality Stress Index To Evaluate Stress As An Analog For Proximate Fitness In The American Crow Within A Matrix Of Landcover Characteristics To Assess Its Potential Contribution To Disease Etiologies, Theodore Lee Grabarz

Antioch University Dissertations & Theses

All organisms occur within spatial and temporal environments to maximize proximate fitness (health) and thus life history outcomes. Previous work has examined the temporal and behavioral aspects of proximate fitness on life history outcomes particularly regarding highly perturbed environments (i.e., climate and land use change, resource extraction, agricultural erosion, etc.). My work focuses on the less examined spatial aspect of these perturbed environments. More specifically, this dissertation examines habitat selection and quality as the basis for understanding stress response (negative and positive feedback mechanisms) to environmental stressors within the larger context of regional or gamma (ɣ) biodiversity. Through the lens …

“Revisiting The Past”: A Redescription Of Physaloptera Retusa (Nemata, Physalopteridae) From Material Deposited In Museums And New Material From Amazon Lizards = “Revisitando O Passado”: Uma Redescrição De Physaloptera Retusa (Nemata, Physalopteridae) A Partir De Material Depositado Em Museus E Novo Material De Lagartos Amazônicos, Lílian Cristina Macedo, Yuri Willkens, Leandro Maurício Oliveira Da Silva, Scott Lyell Gardner, Francisco Tiago De Vasconcelos Melo, Jeannie Nascimento Dos Santos

Scott L. Gardner Publications

Abstract

Physaloptera Rudolphi, 1819 is a genus of nematodes that includes approximately 100 species parasitic in vertebrates around the world. From these, approximately 30 occur in the Neotropical region, with nine reported from neotropical reptiles. Physaloptera spp. are recognized by their distinct morphology of the apical end and characters of the reproductive system. However, despite the fact that the morphological characters for species diagnosis have been firmly established, we frequently find identification problems regarding poorly detailed descriptions and poorly preserved specimens. These may lead to taxonomic incongruencies. Physaloptera retusa (Rudolphi, 1819) is the most common species of the genus and …

Helminth And Protozoan Parasites Of Subterranean Rodents (Chordata, Mammalia, Rodentia) Of The World, Altangerel Tsogtsaikhan Dursahinhan, Daniel A. Kenkel, Scott Lyell Gardner

Scott L. Gardner Publications

Published studies and ten new unpublished records included herein reveal that approximately 174 species of endoparasites (helminths and protozoans) are known from 65 of 163 species of rodents that occupy the subterranean ecotope globally. Of those, 94 endoparasite species were originally described from these rodents. A total of 282 host-parasite associations are summarized from four major zoogeographic regions including Ethiopian, Palearctic/Oriental, Nearctic, and Neotropical. Thirty-four parasite records from the literature have been identified to only the level of the genus. In this summary, ten new records have been added, and the most current taxonomic status of each parasite species is …

Filling The Gap In Distribution Ranges And Conservation Status In Ctenomys (Rodentia: Ctenomyidae), Diego A. Caraballo, Sabrina Laura Lopez, Sebastian Botero-Cañola, Scott Lyell Gardner

Scott L. Gardner Publications

South American subterranean rodents of the genus Ctenomys (Rodentia, Ctenomyidae, tuco-tuco) are one of the most diverse genera among mammals. Recently described species, new taxonomic revisions, and new distribution range delimitation made the revision of distribution areas and conservation status of these mammals mandatory. Implementing the first part of the DAMA protocol (document, assess, monitor, act), here we compile updated sets of species distribution range maps and use these and the number of collection localities to assess the conservation status of ctenomyids. We integrate potential for conservation in protected areas, and levels of habitat transformation to revise previous conservation status …

Tapping Into Natural History Collections To Assess Latitudinal Gradients Of Parasite Diversity, Sebastian Botero-Cañola, Scott Lyell Gardner

Scott L. Gardner Publications

Parasites are key components of the biosphere not only due to their huge diversity, but also because they exert important influences on ecological processes. Nevertheless, we lack an understanding of the biogeographical patterns of parasite diversity. Here, we tap into the potential of biodiversity collections for understanding parasite biogeography. We assess species richness of supracommunities of helminth parasites infecting mammal assemblages in the Nearctic, and describe its relation to latitude, climate, host diversity, and land area. We compiled data from parasitology collections and assessed parasite diversity in Nearctic ecoregions for the entire parasite supracommunity of mammals in each ecoregion, as …

A New Species Of Mathevotaenia (Cestoda: Anoplocephalidae) From The Andean Tuco-Tuco, Ctenomys Opimus (Rodentia: Ctenomyidae), On The Altiplano Of Bolivia, Scott Lyell Gardner, Bennett A. Grappone, Alex Lai

Scott L. Gardner Publications

A new species of Mathevotaenia Akumyan, 1946 (Cestoda: Anoplocephalidae) is described from the Andean tuco-tuco, Ctenomys opimus Wagner 1848 (Rodentia: Ctenomyidae), collected in 1984 on the Altiplano of Bolivia. This is the second species of anoplocephalid cestode recorded from rodents of the genus Ctenomys, the first being Monoecocestus torresi Olsen 1976 from the Maule tuco-tuco, Ctenomys maulinus Philippi 1872, documented in southwestern Argentina. The new species of Mathevotaenia described here has more testes per segment than any other described species of the same genus from South America. The description of a new species from a decades-old specimen highlights the …

Diagnosing Neurocysticercosis In Skeletonized Human Remains Of Forensic Importance, John O. Obafunwa, Karl Reinhard

Karl Reinhard Publications

Neurocysticercosis is endemic in many parts of the underdeveloped and developing countries, with continuous presence in developed countries due to the influx of migrants from regions where the diseases are endemic. Neuroimaging, anatomic pathological techniques, immunodiagnostic tests, clinical examination and epidemiologic considerations will easily provide the diagnosis. However, physicians in developed countries are perhaps progressively missing the diagnosis, and need to re-acquaint themselves with the condition and acquire a high suspicion index. The authors present a medicolegal case where the forensic team made a conclusion of neurocysticercosis (among other diagnoses), following post mortem examination of a largely skeletonized and mummified …

Documenting The Presence Of Chagas Disease In Prehistoric North America: Applying The Stockholm Paradigm To Archaeoparasitology, Part Ii, Karl J. Reinhard, Daniel R. Brooks, Aida Romera Barbera, T. Michael Fink

Karl Reinhard Publications

The DAMA protocol (Document, Assess, Monitor, Act) is the applied aspect of the Stockholm Paradigm. Evidence from archaeology and history of medicine has a demonstrated value in documenting infection risk for specific study areas. Bioarchaeological remains and historical documents show vivid examples of pathology related to the Chagas disease life cycle. The science of archaeology defines the lifestyles that created risk of triatomine kissing bug infestations and trypanosome protozoa infections. Paleogenetics, in the form of molecular analyses of Trypanosoma cruzi, elucidate the temporal origins of genetic variants and adaptation to human environments. We illustrate how these fields reveal the risk …

Exploring The Evolution Of Trypanosoma Cruzi And The Emergence Of Chagas Disease In The Context Of Environmental Change: Applying The Stockholm Paradigm To Archaeoparasitology, Part I, Aida Romera Barbera, Daniel R. Brooks, T. Michael Fink, Karl J. Reinhard

Karl Reinhard Publications

The Stockholm Paradigm is an evolutionary synthesis that explains the emergence of novel pathogens in the context of environmental disturbances. Considering the urgent climate change situation, anticipation stands as key to prevent and mitigate the effects that climate change can have in the emergence of pathogens. However, the success of preventive measures is hindered by a limited knowledge of the interplaying dynamics between biology, environment, and culture leading to emerging infectious diseases. For many decades, bioarchaeologists have been gathering data on past human-environment interactions, therefore contributing to the conversation. Archaeoparasitology, at the intersection between pathology, bioarchaeology, and biology, is uniquely …

Worldwide Host Associations Of The Tick Genus Ixodes Suggest Relationships Based On Environmental Sharing Rather Than On Co-Phylogenetic Events, Agustín Estrada-Peña, Alberto A. Guglielmone, Santiago Nava

Harold W. Manter Laboratory of Parasitology: Library Materials

Abstract

Background

This study aims to capture how ticks of the genus Ixodes gained their hosts using network constructs. We propose two alternative hypotheses, namely, an ecological background (ticks and hosts sharing environmentally available conditions) and a phylogenetic one, in which both partners co-evolved, adapting to existing environmental conditions after the association took place.

Methods

We used network constructs linking all the known pairs of associations between each species and stage of ticks with families and orders of hosts. Faith’s phylogenetic diversity was used to evaluate the phylogenetic distance of the hosts of each species and changes occurring in the …

Hepatozoon Spp. Infection In Wild Canids In The Eastern United States, Eliza Baker, Alex Clemson, Debra Miller, Kayla Buck Garrett, Christopher A. Cleveland, Justin Brown, Kyle Van Why, Richard W. Gerhold Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

Background Hepatozoon spp. are apicomplexan parasites known to cause musculoskeletal disease in a variety of animals. Two species are known to infect wild and domestic canids in the United States: Hepatozoon canis and H. americanum.

Methods In this study, blood, heart, and/or spleen samples were collected from 278 wild canids (180 coyotes, 93 red foxes, and 5 gray foxes) in the eastern US and tested via PCR for Hepatozoon. Histology slides of heart and skeletal muscle were assessed for Hepatozoon cysts and associated inflammation when fresh tissue was available (n = 96).

Results Hepatozoon spp. were …

Natural Variation In Temperature-Modulated Immunity To Pseudomonas Syringae Pv. Tomato (Pst Dc3000) In Arabidopsis Thaliana Plants, Christina A. M. Rossi

Theses and Dissertations (Comprehensive)

Studies conducted on the model plant-pathogen system Arabidopsis thaliana-Pseudomonas syringae pv. tomato (Pst) showed that elevated temperature suppresses the pathogen-induced production of salicylic acid (SA), which is a key plant defence hormone. This increased host vulnerability at higher temperatures is due to downregulated expression of CALMODULIN BINDING PROTEIN 60-LIKE G (CBP60g) and SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1), which encode master regulators of SA production. Collectively, these previous studies only focused on one natural accession of Arabidopsis called Columbia-0 (Col-0). However, the intraspecific variation in Arabidopsis immunity phenotypes under elevated temperature remains unknown. To fill this critical knowledge gap, my …

The First Complete Genome Of The Simian Malaria Parasite Plasmodium Brasilianum, Marko Bajic, Shashidhar Ravishankar, Mili Sheth, Lori A. Rowe, M. Andreina Pacheco, Dhruviben S. Patel, Dhwani Batra, Vladimir Loparev, Christian Olsen, Ananias A. Escalante, Fredrik Vannberg, Venkatachalam Udhayakumar, John W. Barnwell, Eldin Talundzic

Harold W. Manter Laboratory of Parasitology: Library Materials

Naturally occurring human infections by zoonotic Plasmodium species have been documented for P. knowlesi, P. cynomolgi, P. simium, P. simiovale, P. inui, P. inui-like, P. coatneyi, and P. brasilianum. Accurate detection of each species is complicated by their morphological similarities with other Plasmodium species. PCR-based assays offer a solution but require prior knowledge of adequate genomic targets that can distinguish the species. While whole genomes have been published for P. knowlesi, P. cynomolgi, P. simium, and P. inui, no complete genome for P. brasilianum has …

Morphometric And Molecular Characterization Of An Unpigmented Haemosporidian Parasite In The Neotropical Turnip-Tailed Gecko (Thecadactylus Rapicauda), Nubia E. Matta, Leydy P. González, Mario Vargas-Ramírez, Gediminas Valkiūnas, Ananias A. Escalante, M. Andreína Pacheco

Harold W. Manter Laboratory of Parasitology: Library Materials

Morphological traits from blood stages have been the gold standard for determining haemosporidian parasite species. However, the status of some taxa and the value of such traits in parasites from reptiles remain contentious. The scarce sampling of these species worsens the situation, and several taxa lack molecular data. A survey was performed in the Magdalena Department in Colombia, where 16 species of reptiles were captured. A peculiar haemosporidian parasite was found in the Turnip-tailed gecko Thecadactylus rapicauda. This haemosporidian does not show malarial pigment in blood stages under light microscopy; thus, it fits the Garnia genus’s characters belonging to …

The Ecology And Epidemiology Of Malaria Parasitism In Wild Chimpanzee Reservoirs, Erik J. Scully, Weimin Liu, Yingying Li, Jean-Bosco N. Ndjango, Martine Peeters, Shadrack Kamenya, Anne E. Pusey, Elizabeth V. Lonsdorf, Crickette M. Sanz, David B. Morgan, Alex K. Piel, Fiona A. Stewart, Mary K. Gonder, Nicole Simmons, Caroline Asiimwe, Klaus Zuberbuehler, Kathelijne Koops, Colin A. Chapman, Rebecca Chancellor, Aaron S. Rundus, Michael A. Huffman, Nathan D. Wolfe, Manoj T. Duraisingh, Beatrice H. Hahn, Richard W. Wrangham

Anthropology & Sociology Faculty Publications

Chimpanzees (Pan troglodytes) harbor rich assemblages of malaria parasites, including three species closely related to P. falciparum (sub-genus Laverania), the most malignant human malaria parasite. Here, we characterize the ecology and epidemiology of malaria infection in wild chimpanzee reservoirs. We used molecular assays to screen chimpanzee fecal samples, collected longitudinally and cross-sectionally from wild populations, for malaria parasite mitochondrial DNA. We found that chimpanzee malaria parasitism has an early age of onset and varies seasonally in prevalence. A subset of samples revealed Hepatocystis mitochondrial DNA, with phylogenetic analyses suggesting that Hepatocystis appears to cross species barriers more easily than Laverania. …

Exploring The Relationships Between South Texas Northern Bobwhite Populations And Cecal Worms Via System Dynamics, Nicole J. Traub, Benjamin L. Turner, Leonard A. Brennan, Alan M. Fedynich

National Quail Symposium Proceedings

Community ecology historically focused on plants and free-living organisms; however, problems such as defining habitat boundaries and obtaining adequate sample sizes arise when evaluating such communities. The unique nature of host-helminth systems allows parasite community ecologists to avoid these problems when testing ecological hypotheses. Unlike free-living communities that have artificially constructed boundaries, parasite communities have well-defined unambiguous boundaries within host individuals. Due to the inherently complex and dynamic nature of ecological systems, traditional experimental methods often require expensive, long-term trials beyond investigators’ time and resource budgets. Conversely, a system dynamics approach facilitates learning about such systems via simulation of ecosystem …

The Influences Of Disperser Behavior, Host Availability, And Environmental Conditions On The Distribution Of Oak Mistletoe [Phoradendron Leucarpum (Raf.) Reveal & M. C. Johnst.] In Eastern Virginia And North Carolina, Nicholas Pearce Flanders

Biological Sciences Theses & Dissertations

Mistletoes are shrubs that typically parasitize the branches of host trees and rely on avian frugivores for seed dispersal. Because mistletoes are restricted to a narrow range of suitable recruitment sites and avian frugivores are more visible than other guilds of seed dispersers, mistletoe-frugivore systems afford opportunities for assessing the roles of dispersal limitation and local environment in determining plant distribution. These mechanisms have been proposed as determinants of the observed association of oak mistletoe [Phoradendron leucarpum (Raf.) Reveal & M. C. Johnst.] with forested wetlands in eastern Virginia and North Carolina, USA. I tested the alternative hypothesis that …

Characterizing Endogenous Dicer Products To Unravel Novel Rnai Biogenesis Pathways, Jacob Oche Peter

Dissertations

ABSTRACT

RNA interference (RNAi) is a pervasive gene regulatory mechanism in eukaryotes based on the action of multiple classes of small RNA (sRNA). Exploiting RNAi pathways in non-model systems have great potential for creating potent RNAi technologies. Here, we accessed RNAi-mediated control of gene expression in the two-spotted spider mite, Tetranychus urticae (T. urticae) using engineered dsRNA designed to modulate the host RNAi pathway and increase RNAi efficacy. Analysis of Dicer (Dcr) generated fragments revealed how exogenous RNAs access the host RNAi pathway in this animal, opening avenues for designing RNAi technology for their control. Further, some organisms …