Nathan T Mortimer

Nathan T Mortimer
Oregon State University | OSU · Department of Biochemistry and Biophysics

PhD

About

58
Publications
7,265
Reads
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587
Citations
Introduction
My research is focused on uncovering the mechanisms that determine the outcome of infection in host-parasite interactions, using a Drosophila melanogaster-parasitoid wasp model host-parasite system. In this research I take an integrative approach, in which I use molecular genetics, genomics and bioinformatic techniques to investigate the molecular basis of the interactions between host immune responses and parasite virulence factors.
Additional affiliations
August 2015 - August 2022
Illinois State University
Position
  • Professor (Assistant)
February 2014 - June 2015
University of Denver
Position
  • Visiting Scientist
August 2013 - February 2014
The University of Warwick
Position
  • Professor (Assistant)
Education
August 2003 - May 2009
Emory University
Field of study
  • Genetics and Molecular Biology

Publications

Publications (58)
Article
Full-text available
In nature, larvae of the fruitfly Drosophila melanogaster are commonly infected by parasitoid wasps, and so have evolved a robust immune response to counter wasp infection. In this response, fly immune cells form a multilayered capsule surrounding the wasp egg, leading to death of the parasite. Many of the molecular mechanisms underlying this encap...
Article
Full-text available
Because parasite virulence factors target host immune responses, identification and functional characterization of these factors can provide insight into poorly understood host immune mechanisms. The fruit fly Drosophila melanogaster is a model system for understanding humoral innate immunity, but Drosophila cellular innate immune responses remain...
Article
Full-text available
In nature, larvae of the fruit fly Drosophila melanogaster are commonly infected by parasitoid wasps. Following infection, flies mount an immune response termed cellular encapsulation in which fly immune cells form a multilayered capsule that covers and kills the wasp egg. Parasitoids have thus evolved virulence factors to suppress cellular encapsu...
Article
Hymenopteran parasitoid wasps are a diverse collection of species that infect arthropod hosts and use factors found in their venoms to manipulate host immune responses, physiology, and behaviour. Whole parasitoid venoms have been profiled using proteomic approaches, and here we present a bioinformatic characterization of the venom protein content f...
Article
Full-text available
Significance The ability of immune cells to distinguish self tissue from nonself pathogens is a key characteristic of immunity, allowing responses to be targeted against invading pathogens while protecting against self-directed immune damage. The recognition of nonself by innate immune cells has been extensively characterized, but the mechanisms th...
Article
How do pathogens deal with antimicrobial oxidants produced by the innate immune system during infection? Uropathogenic Escherichia coli (UPEC), the most common etiological agent of urinary tract infections (UTIs), is particularly exposed to infiltrating neutrophils and, therefore, must counter elevated levels of the antimicrobial oxidant HOCl to es...
Article
Full-text available
Organisms are commonly infected by a diverse array of pathogens and mount functionally distinct responses to each of these varied immune challenges. Host immune responses are characterized by the induction of gene expression, however, the extent to which expression changes are shared among responses to distinct pathogens is largely unknown. To exam...
Article
Full-text available
ABSTRACT The Genomics Education Partnership (GEP) engages students in a course-based undergraduate research experience (CURE). To better understand the student attributes that support success in this CURE, we asked students about their attitudes using previously published scales that measure epistemic beliefs about work and science, interest in sci...
Preprint
Full-text available
Immune self-tolerance is the ability of a host's immune system to recognize and avoid triggering immune responses against self-tissue. This allows the host to avoid self-directed immune damage while still responding appropriately to pathogen infection. A breakdown of self-tolerance can lead to an autoimmune state in which immune cells target health...
Article
Avian eggshell pigmentation may provide information about a female’s physiological condition, in particular her state of oxidative balance. Previously we found that female house wrens (Troglodytes aedon Vieillot, 1809) with lighter, less-maculated, and redder ground-colored shells were older and produced heavier offspring than females laying darker...
Article
Full-text available
As organisms age, they often accumulate protein aggregates that are thought to be toxic, potentially leading to age‐related diseases. This accumulation of protein aggregates is partially attributed to a failure to maintain protein homeostasis. A variety of genetic factors have been linked to longevity, but how these factors also contribute to prote...
Preprint
Full-text available
Background: Organisms are commonly infected by a diverse array of pathogen types including bacteria, fungi, viruses, and parasites, and mount functionally distinct responses to each of these varied immune challenges. Host immune responses are characterized by the induction of gene expression in response to infection. However, the extent to which ex...
Preprint
Full-text available
The ability to overcome stressful environments is critical for pathogen survival in the host. One challenge for bacteria is the exposure to reactive chlorine species (RCS), which are generated by innate immune cells as critical part of the oxidative burst. Hypochlorous acid (HOCl) is the most potent antimicrobial RCS and associated with extensive m...
Article
Full-text available
By age 17, almost 80% of US children have dental caries resulting from cariogenic bacteria that could be reduced with tooth brushing. This cross-sectional, correlational pilot study aims to understand the association between tooth brushing and oral microbiota in children. Oral specimens and survey data were collected from a convenience sample of 16...
Article
Full-text available
In nature, Drosophila melanogaster larvae are infected by parasitoid wasps and mount a cellular immune response to this infection. Several conserved signaling pathways have been implicated in coordinating this response, however our understanding of the integration and regulation of these pathways is incomplete. Members of the S1A serine protease fa...
Article
Full-text available
The interactions between Drosophila melanogaster and the parasitoid wasps that infect Drosophila species provide an important model for understanding host–parasite relationships. Following parasitoid infection, D. melanogaster larvae mount a response in which immune cells (hemocytes) form a capsule around the wasp egg, which then melanizes, leading...
Preprint
Full-text available
The interactions between Drosophila melanogaster and the parasitoid wasps that infect Drosophila species provide an important model for understanding host-parasite relationships. Following parasitoid infection, D. melanogaster larvae mount a response in which immune cells (hemocytes) form a capsule around the wasp egg, which then melanizes leading...
Article
Full-text available
As organisms are constantly exposed to the damaging effects of oxidative stress through both environmental exposure as well as internal metabolic processes, they have evolved a variety of mechanisms to cope with this stress. One such mechanism is the highly conserved p38 MAPK (p38K) pathway, which is known to be to post-translationally activated in...
Article
Full-text available
Scientists are sequencing new genomes at an increasing rate with the goal of associating genome contents with phenotypic traits. After a new genome is sequenced and assembled, structural gene annotation is often the first step in analysis. Despite advances in computational gene prediction algorithms, most eukaryotic genomes still benefit from manua...
Article
Full-text available
Differences in avian eggshell pigmentation could be an honest signal of female quality that males use to inform their nestling provisioning effort. We investigated whether among-individual variation in protoporphyrin-based eggshell pigmentation in house wrens (Troglodytes aedon) reflects female fitness-associated traits and whether males use that i...
Article
Full-text available
A hallmark of the research experience is encountering difficulty and working through those challenges to achieve success. This ability is essential to being a successful scientist, but replicating such challenges in a teaching setting can be difficult. The Genomics Education Partnership (GEP) is a consortium of faculty who engage their students in...
Preprint
Full-text available
Scientists are sequencing new genomes at an increasing rate with the goal of associating genome contents with phenotypic traits. After a new genome is sequenced and assembled, structural gene annotation is often the first step in analysis. Despite advances in computational gene prediction algorithms, most eukaryotic genomes still benefit from manua...
Preprint
Full-text available
As organisms are constantly exposed to the damaging effects of oxidative stress through both environmental exposure as well as internal metabolic processes, they have evolved a variety of mechanisms to cope with this stress. One such mechanism is the highly conserved p38 MAPK (p38K) pathway, which is known to be to post-translationally activated in...
Preprint
Full-text available
As organisms age, they often accumulate protein aggregates that are thought to be toxic, potentially leading to age-related diseases. This accumulation of protein aggregates is partially attributed to a failure to maintain protein homeostasis. A variety of genetic factors have been linked to longevity, but how these factors also contribute to prote...
Preprint
Full-text available
Innate immune responses depend on the action of multiple conserved signaling pathways. Pathways important for activation of humoral immune responses following microbial infection are well-characterized in the genetic model species Drosophila melanogaster, but our understanding of fly cellular immunity, and how parasites suppress it, is relatively f...
Preprint
Full-text available
Hymenopteran parasitoid wasps are a diverse collection of species that infect arthropod hosts and use factors found in their venoms to manipulate host immune responses, physiology, and behaviour. Whole parasitoid venoms have been profiled using proteomic approaches, and here we present a bioinformatic characterization of the venom protein content f...
Article
Full-text available
The discordance between genome size and the complexity of eukaryotes can partly be attributed to differences in repeat density. The Muller F element (~5.2 Mb) is the smallest chromosome in Drosophila melanogaster, but it is substantially larger (>18.7 Mb) in Drosophila ananassae To identify the major contributors to the expansion of the F element a...
Article
Full-text available
The Caenorhabditis elegans gene sup-26 encodes a well-conserved RNA-recognition motif-containing RNA-binding protein (RBP) that functions in dendrite morphogen-esis of the PVD sensory neuron. The Drosophila ortholog of sup-26, alan shepard (shep), is expressed throughout the nervous system and has been shown to regulate neuronal remod-eling during...
Article
Full-text available
The regulation of dendritic branching is critical for sensory reception, cell-cell communication within the nervous system, learning, memory, and behavior. Defects in dendrite morphology are associated with several neurological disorders, thus an understanding of the molecular mechanisms that govern dendrite morphogenesis is important. Recent inves...
Article
Full-text available
The regulation of dendritic branching is critical for sensory reception, cell-cell communication within the nervous system, learning, memory, and behavior. Defects in dendrite morphology are associated with several neurological disorders, thus an understanding of the molecular mechanisms that govern dendrite morphogenesis is important. Recent inves...
Article
Full-text available
The large repertoire of circadian rhythms in diverse organisms depends on oscillating central clock genes, input pathways for entrainment, and output pathways for controlling rhythmic behaviors. Stress-activated p38 MAP Kinases (p38K), although sparsely investigated in this context, show circadian rhythmicity in mammalian brains and are considered...
Article
Full-text available
The fruit fly Drosophila melanogaster and its endoparasitoid wasps are a developing model system for interactions between host immune responses and parasite virulence mechanisms. In this system, wasps use diverse venom cocktails to suppress the conserved fly cellular encapsulation response. Although numerous genetic tools allow detailed characteriz...
Data
PCR primers used to amplify L. boulardi genes. (DOCX)
Data
PCR primers used to amplify L. heterotoma genes. (DOCX)
Data
All identified L. boulardi venom cDNAs in Fasta format. (FASTA)
Data
All identified L. heterotoma venom cDNAs in Fasta format. (FASTA)
Data
All identified L. boulardi venom proteins in Fasta format. (FASTA)
Data
Results from gene ontology analysis. Dots preceding category ID indicate category level relative to top-level category, GO:0003674, molecular function. pbonferroni <0.05 (DOCX)
Data
All identified L. heterotoma venom proteins in Fasta format. (FASTA)
Article
Full-text available
Hosts have numerous defenses against parasites, of which behavioral immune responses are an important but underappreciated component. Here we describe a behavioral immune response that Drosophila melanogaster uses against endoparasitoid wasps. We found that when flies see wasps, they switch to laying eggs in alcohol-laden food sources that protect...
Data
Loss of ago does not deregulate Cyclin E levels in body wall muscle cells. Comparison of Cyclin E levels in VLM12 and VLM13 in 5053A-Gal4:UAS-GFP,UAS-agoΔF larvae. Larvae were stained with a-Cyclin E antiserum (red). GFP marks VLM12 (green). (TIF)
Data
Number of tracheal terminal branches terminating on VLM12. Number of tracheal terminal branches terminating on the VLM12 muscle segment in the indicated genotypes. P-values are indicated. (DOCX)
Data
Relative induction of hypoxia-responsive genes in normoxic ago larvae. Relative levels of mRNAs of the indicated genes normalized to the level of each mRNA in wt control larvae. Experiments were done in triplicate. P-values provided for each gene. (DOCX)
Article
Full-text available
The gene () encodes the F-box/WD-repeat protein substrate specificity factor for an SCF (Skp/Cullin/F-box)-type polyubiquitin ligase that inhibits tumor-like growth by targeting proteins for degradation by the proteasome. The Ago protein is expressed widely in the fly embryo and larva and promotes degradation of pro-proliferative proteins in mitoti...
Article
Full-text available
The tracheal system of Drosophila melanogaster is an interconnected network of gas-filled epithelial tubes that develops during embryogenesis and functions as the main gas-exchange organ in the larva. Larval tracheal cells respond to hypoxia by activating a program of branching and growth driven by HIF-1alpha/sima-dependent expression of the breath...
Article
Full-text available
The archipelago gene (ago) encodes the F-box specificity subunit of an SCF(skp-cullin-f box) ubiquitin ligase that inhibits cell proliferation in Drosophila melanogaster and suppresses tumorigenesis in mammals. ago limits mitotic activity by targeting cell cycle and cell growth proteins for ubiquitin-dependent degradation, but the diverse developme...
Article
Full-text available
The guidance molecule Netrin and its receptor DCC (deleted in colorectal cancer) attract commissural axons toward the midline en route to their final destination. To test whether these molecules can also guide dendrites, we studied the contralateral dendrites of zebrafish octavolateralis efferent (OLe) neurons, which are unusual in that they naviga...
Article
Full-text available
Drosophila development depends on stable boundaries between cellular territories, such as the embryonic parasegment boundaries and the compartment boundaries in the imaginal discs. Patterning in the compound eye is fundamentally different: the boundary is not stable, but moves (the morphogenetic furrow). Paradoxically, Hedgehog signaling is essenti...
Article
Full-text available
During neurogenesis in the ventral nerve cord of the Drosophila embryo, Notch signaling participates in the pathway that mediates asymmetric fate specification to daughters of secondary neuronal precursor cells. In the NB4-2 --> GMC-1 --> RP2/sib lineage, a well-studied neuronal lineage in the ventral nerve cord, Notch signaling specifies sib fate...

Projects

Project (1)