I am a postdoctoral fellow in the Schneider lab studying innate immunity. I grew up in Utah, where I learned to love the outdoors and the wondrous diversity of life. Growing up, I enjoyed having a variety of pets including: dogs, lizards, snakes, fish, spiders, a tortoise, and a variety of insects. I have always been interested in science and can recall a seventh-grade career essay in which I wrote that I wanted to be a geneticist when I grew up, even though I didn't really know what that meant at the time. I have not deviated from that desire and thoroughly enjoy scientific inquiry. One of the things I enjoy most about biology is the opportunity to study life and science wherever you are. I have participated in field studies in Antarctica, Europe, and the United States, studying the biodiversity of nematodes and tardigrades. I love field work and hope to continue making it a regular part of my research.
I finished my doctorate studying host seeking and olfaction in parasitic nematodes in Paul Sternberg’s lab at Caltech. Currently I study immunity using the fruit fly as a model system. There is a new model describing microbial pathogenesis in animals that helps differentiate two major arms of the immune system. This model distinguishes between a host’s ability to resist or tolerate a pathogen. Resistance is the ability of a host to reduce microbe loads while disease tolerance is the dose response curve correlating microbe load to host health; a tolerant host will show reduced health loss in the face of high pathogen loads. Resistance and tolerance are separable and thus both can be employed to fight infections. I am investigating the roles of resistance and disease tolerance in immunity, studying both bacterial pathogens as well as cancer.
Honors & Awards
Postdoctoral fellowship: Ruth L. Kirschstein-NRSA, Stanford Genomics Training Program, National Institutes of Health and Stanford University (2013-2014)
Lawrence L. and Audrey W. Ferguson Prize, California Institute of Technology (2013)
John M. Webster Outstanding Student Award, Society of Nematologists and the Nathan A. Cobb Foundation (2012)
Everhart Distinguished Graduate Student Lecturer Award, California Institute of Technology (2012)
Best poster in Ecology and Evolution, 2nd place award., International worm meeting, Genetics Society of America (2009)
Graduate fellowship: Ruth L. Kirschstein-NRSA, Caltech Genetics Training Program, National Institutes of Health and California Institute of Technology (2007-2010)
Research award: "Natural gene insertion events as a model for viral associated cancer.", Office of Research and Creative activities, Brigham Young University (2005)
Research award: "Molecular evolution and amelioration in plant-parasitic nematodes.", Office of Research and Creative activities, Brigham Young University (2005)
Research award: "Selection, horizontal gene transfer, and convergent molecular evolution.", Office of Research and Creative activities, Brigham Young University (2004)
Boards, Advisory Committees, Professional Organizations
Member, Society of Nematologists (2004 - Present)
Member, Genetics Society of America (2009 - Present)
Chair of the graduate student committee, Society of Nematologists (2011 - 2012)
Education committee member, Society of Nematologists (2011 - Present)
Ph.D., California Institute of Technology, Genetics (2013)
B.S., Brigham Young University, Microbiology (2006)
David Schneider, Postdoctoral Faculty Sponsor
Current Research and Scholarly Interests
Innate immune memory and immune resistance and disease tolerance to cancer.
David Schneider, (1/7/2013)
Microsporidia-nematode associations in methane seeps reveal basal fungal parasitism in the deep sea
Frontiers in Microbiology
View details for DOI 10.3389/fmicb.2014.00043
A Modified Mole Cricket Lure and Description of Scapteriscus borellii (Orthoptera: Gryllotalpidae) Range Expansion and Calling Song in California.
2014; 43 (1): 146-56
Invasive mole cricket species in the genus Scapteriscus have become significant agricultural pests and are continuing to expand their range in North America. Though largely subterranean, adults of some species, such as Scapteriscus borellii Giglio-Tos 1894, are capable of long dispersive flights and phonotaxis to male calling songs to find suitable habitats and mates. Mole crickets in the genus Scapteriscus are known to be attracted to and can be caught by audio lure traps that broadcast synthesized or recorded calling songs. We report improvements in the design and production of electronic controllers for the automation of semipermanent mole cricket trap lures as well as highly portable audio trap collection designs. Using these improved audio lure traps, we collected the first reported individuals of the pest mole cricket S. borellii in California. We describe several characteristic features of the calling song of the California population including that the pulse rate is a function of soil temperature, similar to Florida populations of S. borellii. Further, we show that other calling song characteristics (carrier frequency, intensity, and pulse rate) are significantly different between the populations.
View details for DOI 10.1603/EN13152
View details for PubMedID 24472207
The Draft Genome and Transcriptome of Panagrellus redivivus Are Shaped by the Harsh Demands of a Free-Living Lifestyle
2013; 193 (4): 1279-?
Nematodes compose an abundant and diverse invertebrate phylum with members inhabiting nearly every ecological niche. Panagrellus redivivus (the "microworm") is a free-living nematode frequently used to understand the evolution of developmental and behavioral processes given its phylogenetic distance to Caenorhabditis elegans. Here we report the de novo sequencing of the genome, transcriptome, and small RNAs of P. redivivus. Using a combination of automated gene finders and RNA-seq data, we predict 24,249 genes and 32,676 transcripts. Small RNA analysis revealed 248 microRNA (miRNA) hairpins, of which 63 had orthologs in other species. Fourteen miRNA clusters containing 42 miRNA precursors were found. The RNA interference, dauer development, and programmed cell death pathways are largely conserved. Analysis of protein family domain abundance revealed that P. redivivus has experienced a striking expansion of BTB domain-containing proteins and an unprecedented expansion of the cullin scaffold family of proteins involved in multi-subunit ubiquitin ligases, suggesting proteolytic plasticity and/or tighter regulation of protein turnover. The eukaryotic release factor protein family has also been dramatically expanded and suggests an ongoing evolutionary arms race with viruses and transposons. The P. redivivus genome provides a resource to advance our understanding of nematode evolution and biology and to further elucidate the genomic architecture leading to free-living lineages, taking advantage of the many fascinating features of this worm revealed by comparative studies.
View details for DOI 10.1534/genetics.112.148809
View details for Web of Science ID 000316937300020
View details for PubMedID 23410827
Origin and Evolution of Dishevelled
G3-GENES GENOMES GENETICS
2013; 3 (2): 251-262
Dishevelled (Dsh or Dvl) is an important signaling protein, playing a key role in Wnt signaling and relaying cellular information for several developmental pathways. Dsh is highly conserved among metazoans and has expanded into a multigene family in most bilaterian lineages, including vertebrates, planarians, and nematodes. These orthologs, where explored, are known to have considerable overlap in function, but evidence for functional specialization continues to mount. We performed a comparative analysis of Dsh across animals to explore protein architecture and identify conserved and divergent features that could provide insight into functional specialization with an emphasis on invertebrates, especially nematodes. We find evidence of dynamic evolution of Dsh, particularly among nematodes, with taxa varying in ortholog number from one to three. We identify a new domain specific to some nematode lineages and find an unexpected nuclear localization signal conserved in many Dsh orthologs. Our findings raise questions of protein evolution in general and provide clues as to how animals have dealt with the complex intricacies of having a protein, such as Dsh, act as a central messenger hub connected to many different and vitally important pathways. We discuss our findings in the context of functional specialization and bring many testable hypotheses to light.
View details for DOI 10.1534/g3.112.005314
View details for Web of Science ID 000314881600010
View details for PubMedID 23390601
Nematode-Bacterium Symbioses-Cooperation and Conflict Revealed in the "Omics" Age
2012; 223 (1): 85-102
Nematodes are ubiquitous organisms that have a significant global impact on ecosystems, economies, agriculture, and human health. The applied importance of nematodes and the experimental tractability of many species have promoted their use as models in various research areas, including developmental biology, evolutionary biology, ecology, and animal-bacterium interactions. Nematodes are particularly well suited for the investigation of host associations with bacteria because all nematodes have interacted with bacteria during their evolutionary history and engage in a variety of association types. Interactions between nematodes and bacteria can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved, their study can provide broader insights into other types of associations, including those relevant to human diseases. Recently, genome-scale studies have been applied to diverse nematode-bacterial interactions and have helped reveal mechanisms of communication and exchange between the associated partners. In addition to providing specific information about the system under investigation, these studies also have helped inform our understanding of genome evolution, mutualism, and innate immunity. In this review we discuss the importance and diversity of nematodes, "omics"' studies in nematode-bacterial systems, and the wider implications of the findings.
View details for Web of Science ID 000309089500009
View details for PubMedID 22983035
Incorporating Genomics into the Toolkit of Nematology
JOURNAL OF NEMATOLOGY
2012; 44 (2): 191-205
The study of nematode genomes over the last three decades has relied heavily on the model organism Caenorhabditis elegans, which remains the best-assembled and annotated metazoan genome. This is now changing as a rapidly expanding number of nematodes of medical and economic importance have been sequenced in recent years. The advent of sequencing technologies to achieve the equivalent of the $1000 human genome promises that every nematode genome of interest will eventually be sequenced at a reasonable cost. As the sequencing of species spanning the nematode phylum becomes a routine part of characterizing nematodes, the comparative approach and the increasing use of ecological context will help us to further understand the evolution and functional specializations of any given species by comparing its genome to that of other closely and more distantly related nematodes. We review the current state of nematode genomics and discuss some of the highlights that these genomes have revealed and the trend and benefits of ecological genomics, emphasizing the potential for new genomes and the exciting opportunities this provides for nematological studies.
View details for Web of Science ID 000320451700013
View details for PubMedID 23482088
- An Entomopathogenic Nematode by Any Other Name PLOS PATHOGENS 2012; 8 (3)
Olfaction shapes host-parasite interactions in insect-parasitic nematodes
2012; 109 (35): E2324-E2333
View details for DOI 10.1073/pnas.1211436109
- Entomopathogenic nematodes Current Biology 2012; 22 (11): R430-R431
Outcrossing and crossbreeding recovers deteriorated traits in laboratory cultured Steinernema carpocapsae nematodes
INTERNATIONAL JOURNAL FOR PARASITOLOGY
2011; 41 (7): 801-809
The nematode Steinernema carpocapsae infects and kills many pest insects in agro-ecosystems and is commonly used in biocontrol of these pests. Growth of the nematodes prior to distribution for biocontrol commonly results in deterioration of traits that are essential for nematode persistence in field applications. To better understand the mechanisms underlying trait deterioration of the efficacy of natural parasitism in entomopathogenic nematodes, we explored the maintenance of fitness related traits including reproductive capacity, heat tolerance, virulence to insects and 'tail standing' (formerly called nictation) among laboratory-cultured lines derived from natural, randomly mating populations of S. carpocapsae. Laboratory cultured nematode lines with fitness-related trait values below wild-type levels regained wild-type levels of reproductive and heat tolerance traits when outcrossed with a non-deteriorated line, while virulence and 'tail standing' did not deteriorate in our experiments. Crossbreeding two trait-deteriorated lines with each other also resulted in restoration of trait means to wild-type levels in most crossbred lines. Our results implicate inbreeding depression as the primary cause of trait deterioration in the laboratory cultured S. carpocapsae. We further suggest the possibility of creating inbred lines purged of deleterious alleles as founders in commercial nematode growth.
View details for DOI 10.1016/j.ijpara.2011.02.005
View details for Web of Science ID 000291377700012
View details for PubMedID 21447341
A Sensory Code for Host Seeking in Parasitic Nematodes
2011; 21 (5): 377-383
Parasitic nematode species often display highly specialized host-seeking behaviors that reflect their specific host preferences. Many such behaviors are triggered by host odors, but little is known about either the specific olfactory cues that trigger these behaviors or the underlying neural circuits. Heterorhabditis bacteriophora and Steinernema carpocapsae are phylogenetically distant insect-parasitic nematodes whose host-seeking and host-invasion behavior resembles that of some devastating human- and plant-parasitic nematodes. We compare the olfactory responses of Heterorhabditis and Steinernema infective juveniles (IJs) to those of Caenorhabditis elegans dauers, which are analogous life stages. The broad host range of these parasites results from their ability to respond to the universally produced signal carbon dioxide (CO(2)), as well as a wide array of odors, including host-specific odors that we identified using thermal desorption-gas chromatography-mass spectroscopy. We find that CO(2) is attractive for the parasitic IJs and C. elegans dauers despite being repulsive for C. elegans adults, and we identify a sensory neuron that mediates CO(2) response in both parasitic and free-living species, regardless of whether CO(2) is attractive or repulsive. The parasites' odor response profiles are more similar to each other than to that of C. elegans despite their greater phylogenetic distance, likely reflecting evolutionary convergence to insect parasitism.
View details for DOI 10.1016/j.cub.2011.01.048
View details for Web of Science ID 000288298900018
View details for PubMedID 21353558
Transcriptional profiling of trait deterioration in the insect pathogenic nematode Heterorhabditis bacteriophora
The success of a biological control agent depends on key traits, particularly reproductive potential, environmental tolerance, and ability to be cultured. These traits can deteriorate rapidly when the biological control agent is reared in culture. Trait deterioration under laboratory conditions has been widely documented in the entomopathogenic nematode (EPN) Heterorhabditis bacteriophora (Hb) but the specific mechanisms behind these genetic processes remain unclear. This research investigates the molecular mechanisms of trait deterioration of two experimental lines of Hb, an inbred line (L5M) and its original parental line (OHB). We generated transcriptional profiles of two experimental lines of Hb, identified the differentially expressed genes (DEGs) and validated their differential expression in the deteriorated line.An expression profiling study was performed between experimental lines L5M and OHB of Hb with probes for 15,220 ESTs from the Hb transcriptome. Microarray analysis showed 1,185 DEGs comprising of 469 down- and 716 up-regulated genes in trait deteriorated nematodes. Analysis of the DEGs showed that trait deterioration involves massive changes of the transcripts encoding enzymes involved in metabolism, signal transduction, virulence and longevity. We observed a pattern of reduced expression of enzymes related to primary metabolic processes and induced secondary metabolism. Expression of sixteen DEGs in trait deteriorated nematodes was validated by quantitative reverse transcription-PCR (qRT-PCR) which revealed similar expression kinetics for all the genes tested as shown by microarray.As the most closely related major entomopathogen to C. elegans, Hb provides an attractive near-term application for using a model organism to better understand interspecies interactions and to enhance our understanding of the mechanisms underlying trait deterioration in biological control agents. This information could also be used to improve the beneficial traits of biological control agents and better understand fundamental aspects of nematode parasitism and mutualism.
View details for DOI 10.1186/1471-2164-10-609
View details for Web of Science ID 000273570700003
View details for PubMedID 20003534
- The southernmost worm, Scottnema lindsayae (Nematoda): diversity, dispersal and ecological stability POLAR BIOLOGY 2007; 30 (7): 809-815
- Nematodes: Model organisms in high school biology The Science Teacher 2007; 74 (7): 34-40
Books and Book Chapters
- Molecular taxonomy and phylogeny Root-knot Nematodes CABI. 2009: 119-137
- Phylogeny and Evolution Nematology Monographs & Perspectives 5 Brill. 2007; 5: 693-733