While you might expect dissertation recognition to focus primarily on the graduate school years, I feel it necessary to hark back to the recessions of the past and not just thank those who helped me over the past five years. years, but also all those who fueled the insatiable flames of my passion for biology and helped me get to where I am today. I want to thank them and all the other members of the Adams lab for making science so much fun. I am also grateful to James Baldwin for encouraging my work every step of the way and for continuing to act as my advocate whenever a scientific or academic opportunity comes my way.
I would like to thank all the many other graduate students, postdocs, faculty, and staff who have befriended me and shared their knowledge, insight, and camaraderie, including: Steven Kuntz, Natalie Kolawa, Liz Wang, Janna Nawroth, Jon Valencia, Eric Erkenbrack , Chris Cronin, Julie Cho, Srimoyee Ghosh, Daniel Leighton, Collin Yu, Mihoko Kato, Ray Deshaies, Michael Dickinson, Victoria Orphan, Wyatt Korff, Eric Matson, Ping Hsueh, Megan Dobro, Alon Zaslaver and many others who have helped me through word and deed, even if only by example. I offer my thanks and gratitude to the Howard Hughes Medical Institute and the National Institutes of Health for generously funding much of the research that takes place in Paul's lab, making it easy to focus on the research and worry less about how to pay for the. My family has been incredibly supportive of the time and effort I have put into this program and I am grateful to have their love, encouragement and support, without which none of this work would have been possible.
I am especially grateful for the beauty and wonder of the natural world and our ability to understand little of it. This thesis concludes with a discussion of the genomic sequencing of entomopathogenic nematodes in the genus Steinernema and the clues these genomes provide regarding the genomic architecture of parasitism.
What Makes a Nematode Entomopathogenic 12
A Sensory Code For Host Seeking in Parasitic
The nematodes develop and reproduce inside the nutrient-rich insect, going through several rounds of reproduction depending on the size of the insect host. These have all been found to be related to insect pathogenic bacteria of the genus Serratia, while O. Three-dimensional reconstruction of the amphisensilla in the microbial feeding nematode, Acrobeles complexus (Nematoda: Rhabditida).
Next, we tested the virulence (i.e., disease-producing capacity [60]) of the six different EPNs against the seven potential hosts. Movement of the parasitic nematode Phasmarhabditis hermaphrodita in the presence of mucus from the host snail Deroceras reticulatum. Immune suppression of the humoral defense of Galleria mellonella (Insecta, Lepidoptera) induced by Steinernema feltiae (Nematoda, Rhabditida): involvement of the parasite cuticle.
Appendix A: Supplementary Materials for Chapter 3 *
Identification of BAG neurons in H. Nomarski's images of the left side of a C. elegans larva and parasitic IJs. Representative snapshots of ion chromatograph data obtained from cricket (upper trace) and waxworm (lower trace) headspace. Compounds identified in multiple traces at relative abundance >20,000 and not present in controls at detectable levels were then positively identified.
The test is a modified version of the host chemotaxis test in which the air stream containing host volatiles is passed through a column of soda lime before entering the test plate. Nematodes are placed in the center of the plate and allowed to spread in the odor gradient. All of the odorants tested are present in plants or bacteria [2–5], and many have been shown to elicit responses from free-living adult nematodes [6–9].
Briefly, 5 instar Galleria mellonella larvae (American Cricket Ranch, Lakeside, CA) were placed in a 5 cm Petri dish with a 55 mm Whatman 1 filter paper acting as a pseudosoil substrate at the bottom of the dish. For all other assays, dauers were not treated with SDS; in these cases, a small population sample was treated with SDS, and worms were only used for behavioral analyzes if almost the entire sampled population survived the SDS treatment. A total of 19 nematode species and 2 outgroup taxa (a priapulid and a nematomorph) were used in the analyzes for Figure S1.
To facilitate comparison of SSU sequences of different lengths, the ends were manually trimmed in MacClade 4 [33] to a maximum length of 1152 characters before alignment, which is the length of the taxon with the shortest sequence, Parastrongyloides trichosuri. The contents of the thermal desorption tubes were transferred to an HP 6890 GC–5973 MS system (Agilent Technologies, USA) with an Eclipse 4660 purge and trap sampler equipped with an air tube desorber attachment (OI Analytical, College Station, TX, USA.). Compounds identified in this way were then positively confirmed using the pure compound (Table S1) and comparing the retention time and mass spectra of the assay-identified compound with the known compound.
Aggregation of larvae of the house cricket, Acheta domesticus (L.), by propionic acid present in the excreta. Identification and isolation of the odor of the moth, Galleria mellonella, and a reappraisal of its sex pheromone. A multivariate analysis of morphometric characters of heterorhabditis species (Nemata:Heterorhabditidae) and the role of morphometrics in the taxonomy of species of the genus.
Appendix B: Supplementary Materials for Chapter 4 *
Photomicrographs of different EPN infective juveniles (IJs) with their host-seeking strategies and host ranges. Earwigs, beetles, and slugs were collected from the top layers of moist soil near the leaking sprinkler. Of the odorants found exclusively in host air, only those identified in multiple experimental replicates in relative abundances ≥ 20,000 and with library matches ≥ 95% confidence are labeled, with the exception of p-dichlorobenzene from house crickets, which was identified with a library match of ~90%.
The majority of earwigs, flathead borers, pill bugs, and snails were collected from the campus of the California Institute of Technology (Figure 4.S2). Dot regions consisted of 2 cm diameter circles on each side of the plate along the diameter, with the center of the circle 1 cm from the edge of the plate. Host air was delivered to one side of the test plate and room air was delivered to the other side of the test plate through holes drilled in the plate covers directly above the center of the point regions.
5 ml of odorant was then placed in the center of one scoring region, while 5 ml of control (either paraffin oil, dH2O or ethanol) was placed in the center of the other scoring region. For all tests, ~2 ml worm pellets containing ~50–150 nematodes were then placed in the center of the test plate. For the mixture test shown in Figure 4.7A, the control test (left row) contained 5 mL of an odorant mixture containing 10-1 dilutions of p-dichlorobenzene, hexanal, and γ-terpinene on one side of the chemotaxis plate and a 5 mL paraffin control oil on the other side.
The experimental assay (right bar) had 5 ml of aromatic mixture containing 10-1 dilutions of p-dichlorobenzene, hexanal and γ-terpinene on one side of the chemotaxis plate and 5 ml of aromatic mixture containing 10-1 dilutions of p-dichlorobenzene, hexanal, γ-terpinene and 3-hydroxy-2-butanone on the other. The soil analysis shown in Figure 4.7B used a modified version of the CO2 and host chemotaxis analyses. For the control assay (left bar), one syringe contained 3 g of soil (collected from the sampling site shown in Figure 4.S2) and the other syringe contained air.
A two-factor ANOVA with Bonferroni post-tests was used to compare the responses of different EPNs to different hosts or host-derived odors. P values from ANOVA (factor 1, factor 2, and interaction between the two factors) are given in the figure legends; P values from posttests are given in Supplementary Tables. For example, when we study the responses of different EPNs to different hosts, we show that EPNs respond differently to different hosts (P < 0.0001 for a factor of one), different hosts elicit different overall responses of EPNs (P < 0 .0001 for a factor of two) and different EPNs show different odor response profiles ( P < 0.0001 for interaction).
