Intra-host Dynamics of Malaria Parasites: A Multifaceted Examination of Ecology, Evolution, Drug Resistance, and Competition

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Description
To combat the global antimalarial resistance crisis effective resistance management strategies are needed. To do so, I need to gain a better understanding of the ecological interactions occurring within malaria infections. Despite the importance of the complex interplay among co-infecting…

To combat the global antimalarial resistance crisis effective resistance management strategies are needed. To do so, I need to gain a better understanding of the ecological interactions occurring within malaria infections. Despite the importance of the complex interplay among co-infecting strains, our current knowledge and empirical data of within-host diversity and malaria disease dynamics is limited. In this thesis, I explore the multifaceted dynamics of malaria infections through an ecological lens. My overall research question is: "How do ecological interactions, including niche complementarity, competition dynamics, and the cost of resistance, shape the outcomes of malaria infections, and what implications does this have on understanding and improving resistance management strategies?” In Chapter II, titled “Niche Complementarity in Malaria Infections” I demonstrate that ecological principles are observed in malarial infections by experimentally manipulating the biodiversity of rodent malaria P. chabaudi infections. I observed that some parasites experienced competitive suppression, others experienced competitive facilitation, while others were not impacted. Next, in Chapter III, titled “Determining the Differential Impact of Competition Between Genetically Distinct Plasmodium falciparum Strains” I investigate the differential effect of competition among six genetically distinct strains. The impact of competition varied between strain combinations, and both suppression and facilitation were observed, but most pairings had no competitive interactions. Lastly, in Chapter IV, titled “Assessing Fitness Costs in Malaria Parasites: A Comprehensive Review and Implications for Drug Resistance Management”, I summarize where the field currently stands and what evidence there is for the presence of a fitness cost, or lack thereof, and I highlight the current gaps in knowledge. I found that evidence from field, in vitro, and animal models are overall suggestive of the presence of a fitness cost, however, these costs were not always found. Amid the current focus on malaria eradication, it is crucial to understand the impact of biodiversity on disease severity. By incorporating an ecological approach to infectious disease systems, I can gain insights on within-host interactions and how they impact parasite fitness and transmissibility.
Date Created
2024
Agent

Coevolution between Parabasalia protist symbionts and Neoisoptera hosts.

Description
Protist-dependent termites participate in an obligate symbiosis with the community of protists in their hindgut. The termite host and protist symbionts are interdependent, with the host relying on their symbionts to digest the cellulose in their wood-based diet. Cospeciation is…

Protist-dependent termites participate in an obligate symbiosis with the community of protists in their hindgut. The termite host and protist symbionts are interdependent, with the host relying on their symbionts to digest the cellulose in their wood-based diet. Cospeciation is commonly observed between hosts and their symbiotic protists due to the strict vertical inheritance of symbionts via a process called proctodeal trophallaxis (anus-to-mouth feeding). While codiversification is an expected pattern, not all protist lineages follow this trend and must be investigated on a case-by-case basis. Protist hindgut communities were characterized from termite hosts of the major lineage Neoisoptera (excluding Termitidae, which lack symbiotic protists) in order to observe the differential pattern of cospeciation between protist lineages and host. 18S sequencing was performed on isolated protist cells from the phylum Parabasalia, specifically the genera: Pseudotrichonympha, Holomastigotoides, Cononympha, and Cthulhu and used to infer their phylogenies, evaluate their presence/absence across Neoisoptera hosts, and assess their congruency with the host tree. Pseudotrichonympha is observed to be present in almost all investigated termites and displays a strong pattern of codiversification with hosts, all having a single, unique species present (except one host with two). Holomastigotoides and Cononympha are missing in many host species and subfamilies and are generally found to have 2 species per host (sometimes 3-4 Holomastigotoides species). Cthulhu was present at the lowest frequency which may suggest it is not host specific. This investigation highlights variability of termite and protist coevolution, even when examining symbionts from the same host lineage.
Date Created
2024-05
Agent

Diversity and Phylogeny of Cristamonadea, Parabasalian Symbionts of Termites

Description
The symbiotic relationship between wood-eating termites and hindgut protists is crucial for termite digestion, with protists aiding in lignocellulose degradation. This relationship, dating back to the late Jurassic, resembles the ancestral association between termites and wood roaches, Cryptocercus, established over…

The symbiotic relationship between wood-eating termites and hindgut protists is crucial for termite digestion, with protists aiding in lignocellulose degradation. This relationship, dating back to the late Jurassic, resembles the ancestral association between termites and wood roaches, Cryptocercus, established over 150 million years ago. Paraneotermes simplicicornis and Kalotermes flavicollis, members of the Kalotermitidae family, harbor diverse symbiotic communities pivotal for wood digestion and nitrogen fixation. Parabasalians, such as Cristamonadea, exhibit morphological diversity, with some taxa being joeniids, calonymphids, or devescovinids, residing primarily in termite guts. To explore the coevolutionary history and morphological evolution, this study aims to describe devescovinid communities in P. simplicicornis and K. flavicollis using morphological and molecular approaches. Phylogenetic analysis reveals the relationships among Devescovina, Metadevescovina, Macrotrichomonas, and Calonympha. A misidentification of published sequence AB458854 Joenia annectens provides valuable insights into how species are classified, while the discovery of previously unknown symbionts demonstrates the extent of diversity within these ecosystems. Notably, Clade 2 was named Prototermanova, where novel Cristamonadea species were identified, exhibiting genetic and morphological similarities to Devescovina. Similarly, Clade 4 was labelled Trichoterm, where two novel Devescovina species challenged existing taxonomic classifications. DNA sequencing analyses provided additional validation, highlighting the genetic diversity and potential novelty of symbionts within the termite gut. Morphological examination aligns with previously identified genera, and BLAST analysis supports observations of potential novelty in certain symbionts. Protists from P. simplicicornis and K. flavicollis show close relation to Joenia and Devescovina, respectively. This study sheds light on the complexity of termite symbiotic relationships and underscores the need for continued research to fully comprehend protist diversity within termite guts.
Date Created
2024-05
Agent

Phylogenetic analysis of the iconic termite symbiont, Trichonympha: Novel species and implications for protist sharing

Description
Protist-dependent termites rely on a mutually obligate symbiosis with populations of protists that colonize the hindgut to digest lignocellulose. Protists are transmitted vertically amongst termite colonies so that each member of a termite species shares protist symbionts with its nestmates.…

Protist-dependent termites rely on a mutually obligate symbiosis with populations of protists that colonize the hindgut to digest lignocellulose. Protists are transmitted vertically amongst termite colonies so that each member of a termite species shares protist symbionts with its nestmates. These protist populations are therefore thought to be specific to their host and may serve as an indicator of the evolution and diversification of both termites and protists. However, evolutionary signals may be misinterpreted or interrupted if protists are misidentified, lost, or transferred between termite species. The protist genus Trichonympha is one such taxon whose constituent species deviate from typical phylogenetic patterns of vertical inheritance. In this study, light microscopy, single cell isolation, and 18S sequencing were used to determine the morphology and phylogeny of Trichonympha from Reticulitermes spp., resulting in the discovery of 2 novel species and the revision of the longstanding species, Trichonympha agilis. These results suggest the importance of phylogeny over morphology in species determination, and the confirmation that multiple termite species host the same protist symbionts.
Date Created
2024-05
Agent

A Study of the Cockroach Gut Flagellates in Genus Lophomonas with Single Cell Approaches

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Description
Lophomonas is a genus of flagellated parabasalids that exist as commensal symbionts in the hindguts of a variety of pest cockroaches. The genus contains two species: Lophomonas blattarum and Lophomonas striata. The two species differ by way of bacterial ectosymbionts…

Lophomonas is a genus of flagellated parabasalids that exist as commensal symbionts in the hindguts of a variety of pest cockroaches. The genus contains two species: Lophomonas blattarum and Lophomonas striata. The two species differ by way of bacterial ectosymbionts that attach to the outside of L. striata, giving rise to a striated and spindle-shaped appearance. As the attachment of bacterial symbionts prohibits L. striata from taking up large food particles in the same manner as L. blattarum, it is likely the two species differ in which metabolic genes they possess. Here, a comparison of transcriptomes between the two Lophomonas species show slight differences between the species. Metagenomic analysis of L. striata also presents the possibility of L. striata ectosymbionts as belonging to the genus Parabacteroides.
Date Created
2023
Agent

Revision of the Arizona Rhyssomatus Schoenherr 1837 (Curculionidae: Molytinae: Cleogonini)

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Description
The diverse weevil genus Rhyssomatus Schoenherr, 1837 (Curculionidae: Molytinae: Cleoginini) is currently composed of 175 species throughout the New World (O’Brien et. al 1982; Wibmer et. al 1986). The majority of species are generalist feeders and the group contains many…

The diverse weevil genus Rhyssomatus Schoenherr, 1837 (Curculionidae: Molytinae: Cleoginini) is currently composed of 175 species throughout the New World (O’Brien et. al 1982; Wibmer et. al 1986). The majority of species are generalist feeders and the group contains many notorious agricultural pests, such as Rhyssomatus nigerimus Fahraeus 1837 and R. subtillis Fiedler 1937 that cause thousands of dollars’ worth of crop damage in South America, Central America, and West Indies (Cazado, 2016; Lopez-Guillen, et. al). Although most notable as a crop pest in the literature, the species Rhyssomatus maginatus Fahraeus has also proven to be a great success in an Integrated Pest Management (IPM), controlling the invasive leguminous tree Sesbenia punicea (Cav.) Benth., in South Africa. (Hoffman & Moran 1991; 1992; 1998; 1999). The last century has seen revisions of the Neotropical species with Central American species revised in 1904 by Champion and the South American taxa treated by Fiedler in the subsequent years of 1937 and 1942 (O’Brien & Wibmer, 1982; Wibmer & O’Brien, 1986). However, North American fauna have not been treated since Casey in 1895 and revision is needed as climate change and global trade have more than likely expanded the distributional range of previously lower latitude Rhyssomatus species northwards.
Date Created
2023
Agent

The Cause of Type 1 Diabetes in Nonhereditary Individuals: Viruses and Their Role in Autoimmune Disorders

Description

In completing this thesis project, I attempted to hypothesize the trigger in my own personal diagnosis of type 1 diabetes through literature research as well as further research on viruses and their contribution to autoimmune disorders. I had previously hypothesized…

In completing this thesis project, I attempted to hypothesize the trigger in my own personal diagnosis of type 1 diabetes through literature research as well as further research on viruses and their contribution to autoimmune disorders. I had previously hypothesized that, based on my own family life, type 1 diabetes could possibly be a non-heritable disease despite its consistent inheritance pattern discovered by researchers; however, the research presented in this thesis project rejects this idea and supports the theory that I may have been previously susceptible to this disorder and would have developed type 1 diabetes naturally. There were multiple viruses discovered during the literature research conducted that could possibly have been triggers in the acceleration of my disease. The major link between enteroviruses and autoimmune disorders was discovered, as well as influenza A and SARS-COV-2 and this is explained further in this project.

Date Created
2023-05
Agent

Analysis of Oxymonas Diversity in Cryptotermes brevis Using 18S Sequencing

Description

Oxymonas is a genus of Oxymonad protist found in the hindgut of drywood termites (family Kalotermitidae). Many genera of drywood termites are invasive pests globally. The hindgut microbiome of Cryptotermes brevis, the West Indian drywood termite, has not been described…

Oxymonas is a genus of Oxymonad protist found in the hindgut of drywood termites (family Kalotermitidae). Many genera of drywood termites are invasive pests globally. The hindgut microbiome of Cryptotermes brevis, the West Indian drywood termite, has not been described in detail, and only one published sequence exists of Oxymonas from C. brevis. This study aims to analyze Oxymonas sequences in C. brevis from whole gut genetic material, as well as to dissect its place in phylogenetic trees of Oxymonas and how it fits into specific and evolutionary patterns. To amplify the 18S rRNA gene Oxymonas from C. brevis, the MasterPure DNA extraction kit was used, followed by PCR amplification, followed by agarose gel electrophoresis, followed by purification of the resulting gel bands, followed by ligation/transformation on to an LB agar plate, followed by cloning the resulting bacterial colonies, and topped off by colony screening. The colony screening PCR products were then sequenced in the Genomics Core, assembled in Geneious, aligned and trimmed into a phylogenetic tree, along with several long-read amplicon sequences from Oxymonas in other drywood termites. All whole gut sequences and one amplicon from C. brevis formed a single clade, sharing an ancestor with a sister clade of Oxymonas sp. from C. cavifrons and Procryptotermes leewardensis, but the other long-read fell into its own clade in a different spot on the tree. It can be conjectured that the latter sequence was contaminated and that the C. brevis clones are a monophyletic group, a notion further corroborated by a distantly related clade featuring sequences from Cryptotermes dudleyi, which in turn has a sister taxon of Oxymonas clones from C. cavifrons and P. leewardensis, pointing toward a different kind of co-diversification of the hosts and symbionts rather than cospeciation.

Date Created
2023-05
Agent
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